Ewing Sarcoma

MONDO:0012817 Pathograph 46 Show in embeddings browser bone sarcoma

Ewing sarcoma is an aggressive bone and soft tissue malignancy, most frequent in adolescents and young adults, defined by a FET-ETS fusion. Approximately 85% harbor EWSR1::FLI1; most remaining tumors carry EWSR1::ERG, with rare alternative ETS partners or FUS-containing fusions. EWSR1 rearrangement alone is not specific: diagnosis integrates morphology, immunophenotype and demonstration of a compatible fusion. CIC-rearranged, BCOR-altered and EWSR1-non-ETS round cell sarcomas are distinct entities. Most detailed mechanisms below were established in EWSR1::FLI1 models and should not automatically be generalized to every FET-ETS fusion. EWS-FLI1 rewires GGAA-repeat enhancers, recruits chromatin regulators, activates oncogenic transcription and metabolism, and represses differentiation. Chromatin architecture, fusion dosage, developmental context and secondary alterations modify these programs. R-loop stress and DNA-repair dependencies help explain experimental drug sensitivity, but do not establish universal clinical homologous-recombination deficiency or PARP-inhibitor benefit. The human cell of origin remains unresolved. Intensive systemic chemotherapy and appropriate local control remain the treatment backbone.

Ask OpenScientist

Ask a research question about Ewing Sarcoma. OpenScientist will conduct autonomous deep research using the Disorder Mechanisms Knowledge Base and PubMed literature (typically 10-30 minutes).

Submitting...

Do not include personal health information in your question. Questions and results are cached in your browser's local storage.

30
Pathophys.
4
Histopath.
7
Phenotypes
4
Hypotheses
7
Gaps
46
Pathograph
4
Genes
10
Medical Actions
2
Subtypes
6
Datasets
5
Trials
7
Models
79
References
2
Deep Research
4
Hyp. Reports
🏷

Classifications

ICD-O Morphology
Sarcoma
Harrison's Part
ONCOLOGY HEMATOLOGY
NIH Highlighted Topic
NIH HT 68 childhood adolescent young adult aya cancer
◆

Subtypes

2
Osseous Ewing Sarcoma MONDO:0002625
Primary tumors arising in bone, commonly the pelvis and long bones, with localized pain and swelling. Osseous presentation does not define a different fusion-driven molecular entity.
Extraosseous Ewing Sarcoma MONDO:0018270
Primary tumors arising in soft tissues outside bone, including chest-wall, paravertebral and extremity sites. These share the FET-ETS molecular definition and multimodal treatment principles of osseous Ewing sarcoma.
◈

Mechanistic Hypotheses

4
Canonical EWS-FLI1 fusion enhanceropathy model
canonical_fusion_enhanceropathy_model CANONICAL
Evidence balance 4 support
The canonical fusion transcriptional program includes BAF-supported GGAA enhancer activation, NuRD/LSD1-associated repression, core regulatory circuitry, impaired differentiation and metabolic rewiring. CHD4-mediated structural maintenance is a separate survival dependency. Dynamic endogenous hubs are a preprint-supported refinement. Fusion dosage and multiple coexisting regulatory modules create plasticity; most mechanistic experiments concern EWSR1::FLI1 rather than every FET-ETS partner.
Pathograph links
EWS-FLI1 Fusion Oncogene -> EWS-FLI1 Chromatin Hub Dynamics DIRECT Low-complexity-domain interactions enable chromatin-associated fusion hubs; endogenous dynamic hub measurements are currently supported by a preprint.
EWS-FLI1 Fusion Oncogene -> BAF Complex Retargeting DIRECT The EWSR1-derived low-complexity domain enables EWS-FLI1 to recruit BAF chromatin-remodeling complexes to tumor-specific enhancers.
EWS-FLI1 Fusion Oncogene -> GGAA Microsatellite Enhancer Reprogramming DIRECT EWS-FLI1 occupies GGAA microsatellite repeats and canonical ETS sites, creating de novo enhancers while repressing other enhancer classes.
EWS-FLI1 Fusion Oncogene -> NuRD-LSD1 Transcriptional Repression DIRECT EWS-FLI1 recruits NuRD-associated HDAC and LSD1 activities for transcriptional repression; the separate CHD4 survival dependency does not establish that CHD4 acts through EWS-FLI1 target-gene regulation.
EWS-FLI1 Fusion Oncogene -> ATF4-Serine-Glycine Metabolic Reprogramming DIRECT EWS-FLI1 directly activates ATF4 and metabolic stress-response programs.
EWS-FLI1 Fusion Oncogene -> EWS-FLI1 Dosage and State Plasticity INDIRECT KNOWN INTERMEDIATES The fusion protein is subject to dosage control and its abundance changes the transcriptional state. Intermediates: TRIM8-mediated ubiquitination and degradation
EWS-FLI1 Fusion Oncogene -> EZH2-Associated Differentiation Repression DIRECT Fusion binding at the EZH2 promoter induces expression.
BAF Complex Retargeting -> GGAA Microsatellite Enhancer Reprogramming DIRECT BAF retargeting supports tumor-specific enhancer activation downstream of EWS-FLI1 occupancy.
EWS-FLI1 Chromatin Hub Dynamics -> GGAA Microsatellite Enhancer Reprogramming DIRECT Dynamic EWS-FLI1 hubs concentrate the fusion on chromatin and tune enhancer activation at GGAA microsatellites.
GGAA Microsatellite Enhancer Reprogramming -> Core Regulatory Circuitry Activation DIRECT EWS-FLI1 establishes super-enhancers for KLF15, TCF4, and NKX2-2, building an autoregulatory transcription-factor circuit.
GGAA Microsatellite Enhancer Reprogramming -> Blocked Differentiation DIRECT Aberrant enhancer repression suppresses mesenchymal lineage regulators.
GGAA Microsatellite Enhancer Reprogramming -> HOXD13-Driven Mesenchymal Plasticity DIRECT A fusion-created GGAA enhancer activates the HOXD locus.
ETV6 GGAA Counter-Regulation -> GGAA Microsatellite Enhancer Reprogramming DIRECT ETV6 competition modulates EWS-FLI1 occupancy and output at short GGAA microsatellite enhancers.
ETV6 GGAA Counter-Regulation -> Tumor Cell Proliferation and Survival INDIRECT KNOWN INTERMEDIATES ETV6 restrains excessive fusion activity and maintains a viable undifferentiated tumor state. ETV6 loss instead induces differentiation or cellular stress and suppresses growth in preclinical models. Intermediates: EWS-FLI1 hyperactivation; cellular stress
GGAA Microsatellite Germline Susceptibility Architecture -> GGAA Microsatellite Enhancer Reprogramming DIRECT Germline GGAA repeat length and purity alter the strength of EWS-FLI1 neo-enhancer formation at susceptible loci.
GGAA Microsatellite Germline Susceptibility Architecture -> Tumor Cell Proliferation and Survival INDIRECT KNOWN INTERMEDIATES Susceptibility-locus enhancer activation can increase expression of proliferation-associated transcriptional regulators. Intermediates: EGR2 enhancer activation; RREB1-mediated RAS/MAPK-associated transcription
NuRD-LSD1 Transcriptional Repression -> Blocked Differentiation INDIRECT KNOWN INTERMEDIATES NuRD/LSD1/HDAC-mediated repression helps EWS-FLI1 maintain an immature, transformed state. Intermediates: repression of lineage-regulatory genes; repression of tumor-suppressive target genes
NuRD-LSD1 Transcriptional Repression -> Tumor Cell Proliferation and Survival INDIRECT KNOWN INTERMEDIATES NuRD-associated repression of tumor-suppressive loci contributes to the transformed phenotype. This edge refers to transcriptional repression, not the separate CHD4 DNA-damage buffering mechanism. Intermediates: CHD4-dependent chromatin architecture maintenance; suppression of spontaneous DNA damage
Core Regulatory Circuitry Activation -> Tumor Cell Proliferation and Survival DIRECT Core regulatory transcription factors sustain proliferation and oncogenic signaling pathways in Ewing sarcoma cells.
Core Regulatory Circuitry Activation -> Blocked Differentiation INDIRECT KNOWN INTERMEDIATES Core regulatory circuitry reinforces the undifferentiated tumor state. Intermediates: NKX2-2-mediated repression of mesenchymal features
ATF4-Serine-Glycine Metabolic Reprogramming -> Tumor Cell Proliferation and Survival INDIRECT KNOWN INTERMEDIATES Fusion-driven metabolic rewiring supports biomass production, redox state, and survival in rapidly proliferating tumor cells. Intermediates: serine-glycine biosynthesis; glutamine uptake; one-carbon metabolism
Tumor Cell Proliferation and Survival -> Soft Tissue Mass / Localized Swelling INDIRECT KNOWN INTERMEDIATES Sustained proliferation and impaired differentiation produce the expanding local tumor mass. Intermediates: expansion of poorly differentiated malignant cells
EWS-FLI1 Dosage and State Plasticity -> Tumor Cell Proliferation and Survival DIRECT A tolerated fusion-protein abundance supports survival; excessive expression after TRIM8 loss is deleterious.
EWS-FLI1 Dosage and State Plasticity -> Metastatic Disease INDIRECT UNKNOWN INTERMEDIATES Intermediate depletion and restoration enhanced extravasation and metastatic burden in preclinical models; the corresponding human causal contribution is unresolved.
EWS-FLI1 Dosage and State Plasticity -> Hybrid Mesenchymal Tumor States and Matrix Deposition INDIRECT UNKNOWN INTERMEDIATES Fusion dosage changes can contribute to mesenchymal plasticity, but dosage is not the sole determinant of the observed hybrid programs.
CHD4 Chromatin Architecture Maintenance -> Tumor Cell Proliferation and Survival DIRECT Maintenance of chromatin architecture prevents spontaneous damage and apoptosis.
Tumor-Stroma IL-6/STAT3 Signaling -> Tumor Cell Proliferation and Survival INDIRECT KNOWN INTERMEDIATES Stromal cytokine signaling modifies tumor-cell survival and drug response in a tissue-engineered model. Intermediates: IL-6/STAT3 activation
EZH2-Associated Differentiation Repression -> Blocked Differentiation INDIRECT KNOWN INTERMEDIATES EZH2-associated repression maintains an undifferentiated state in Ewing experimental systems. Intermediates: repression of differentiation-associated genes
HOXD13-Driven Mesenchymal Plasticity -> Hybrid Mesenchymal Tumor States and Matrix Deposition INDIRECT UNKNOWN INTERMEDIATES HOXD13-mediated antagonism contributes to the mesenchymal transcriptional continuum. It is one candidate contributor to hybrid states, not a demonstrated sole cause of CD73 expression or matrix deposition.
Deep research
OpenScientist citations 50 citations 2026-05-28T12:05:36.809795
Show evidence (4 references)
PMID:25453903 SUPPORT In Vitro
"Our findings demonstrate how EWS-FLI1 establishes an oncogenic regulatory program governing both tumor survival and differentiation."
Supports the canonical fusion enhanceropathy model.
PMID:41659683 SUPPORT In Vitro
"We found that endogenous EWS::FLI1 forms dynamic, sub-diffraction-limit hubs with mechanisms of dissolution that prevent the hubs from achieving macroscopic liquid-liquid phase separation."
Endogenous hub imaging is reported in a bioRxiv preprint and is retained as a provisional refinement, not independently established consensus.
PMID:23178492 SUPPORT In Vitro
"Importantly, we demonstrated that the repressive function of EWS/FLI is absolutely required for the oncogenic function of the fusion."
Supports including direct transcriptional repression in the canonical mechanism.
+ 1 more reference
Permissive developmental cell-of-origin model
cell_of_origin_context_model EMERGING
Evidence balance 3 support
Developmental timing and cell state influence fusion tolerance and transformation in human progenitor and animal models. Neural crest and early mesenchymal systems are experimentally permissive, but no unique human lineage or age of initiation is proven. IGF-1/YAP1 cooperation is established in a particular mouse-cell model, and inherited GGAA architecture modifies susceptibility at specific loci without establishing a universal permissive genotype.
Pathograph links
GGAA Microsatellite Germline Susceptibility Architecture -> GGAA Microsatellite Enhancer Reprogramming DIRECT Germline GGAA repeat length and purity alter the strength of EWS-FLI1 neo-enhancer formation at susceptible loci.
GGAA Microsatellite Germline Susceptibility Architecture -> Tumor Cell Proliferation and Survival INDIRECT KNOWN INTERMEDIATES Susceptibility-locus enhancer activation can increase expression of proliferation-associated transcriptional regulators. Intermediates: EGR2 enhancer activation; RREB1-mediated RAS/MAPK-associated transcription
Permissive Progenitor Cell State -> GGAA Microsatellite Enhancer Reprogramming INDIRECT UNKNOWN INTERMEDIATES Developmental chromatin context may determine which GGAA microsatellites become functional EWS-FLI1 enhancers.
IGF-1/YAP1 Developmental Cooperation -> Tumor Cell Proliferation and Survival INDIRECT KNOWN INTERMEDIATES IGF-1/YAP1 signaling can cooperate with EWS-FLI1 to promote stable transformation and tumorigenicity in a developmental mesenchymal context. Intermediates: YAP1/TEAD transcriptional activity; stable transformation of EWS-FLI1-mutant mesenchymal cells
Deep research
OpenScientist citations 46 citations 2026-05-28T12:54:01.089018
Show evidence (3 references)
PMID:41136396 SUPPORT In Vitro
"In summary, we show that EWS::FLI1 enforces an aberrant transcriptome and solely is able to endow transforming capacity when expressed in undifferentiated, early heMSCs."
Supports the developmental-context hypothesis in embryonic mesenchymal stem cells.
PMID:40080499 SUPPORT Model Organism
"We report that transient exposure to IGF-1 concentrations mimicking serum levels during puberty reprograms limb-derived mesenchymal cells of EWS::FLI1-mutant mice to stable transformation and tumorigenicity."
Supports IGF-1/YAP1 signaling as a developmental cooperating mechanism.
PMID:36787739 SUPPORT Human Clinical
"We propose that germline microsatellite variation at the 6p25.1 EwS susceptibility locus could impact downstream gene expression and EwS biology."
Supports inherited GGAA microsatellite architecture as part of the permissive-context model.
Transcription-coupled replication stress vulnerability model
replication_stress_vulnerability_model EMERGING
Evidence balance 3 support
A superimposed vulnerability framework links fusion-driven R-loops, TOP1-stress-dependent DHX9 sequestration, context-dependent BRCA1 impairment, SLFN11 fork arrest, PARP1-supported transcription and USP1-survivin stress buffering. A POLQ/MMEJ defect is supported by a preprint, and SLFN11-loss-associated lipid remodeling is a candidate resistance route. These mechanisms complement the canonical fusion model; experimental sensitivities do not establish uniform clinical HR deficiency or PARP-inhibitor benefit.
Pathograph links
EWS-FLI1 Fusion Oncogene -> ATF4-Serine-Glycine Metabolic Reprogramming DIRECT EWS-FLI1 directly activates ATF4 and metabolic stress-response programs.
EWS-FLI1 Fusion Oncogene -> Transcription-Coupled R-loop Accumulation INDIRECT KNOWN INTERMEDIATES High-output transcription and defective damage-associated transcriptional control promote R-loop accumulation and replication stress. Intermediates: high-output transcription; R-loop accumulation
EWS-FLI1 Fusion Oncogene -> DHX9 Sequestration During Topoisomerase Stress DIRECT In TOP1-poison-treated Ewing cells, EWS-FLI1 binds DHX9 and interferes with resolution of drug-induced R-loops.
EWS-FLI1 Fusion Oncogene -> SLFN11-Dependent Replication Fork Arrest DIRECT EWS-FLI1 directly activates SLFN11 transcription.
EWS-FLI1 Fusion Oncogene -> USP1-Survivin Stress Buffering DIRECT EWS-FLI1 increases USP1 expression and thereby supports survivin-dependent stress tolerance.
EWS-FLI1 Fusion Oncogene -> Proposed POLQ Splicing and MMEJ Defect INDIRECT KNOWN INTERMEDIATES Fusion expression perturbs faithful POLQ splicing in the reported cellular models; this preprint-derived edge is provisional. Intermediates: POLQ exon 25 skipping and reduced polymerase theta expression
EWS-FLI1 Fusion Oncogene -> PARP1-Supported Fusion Transcription DIRECT Fusion expression maintains PARP1 expression in a reciprocal transcriptional dependency.
NuRD-LSD1 Transcriptional Repression -> Tumor Cell Proliferation and Survival INDIRECT KNOWN INTERMEDIATES NuRD-associated repression of tumor-suppressive loci contributes to the transformed phenotype. This edge refers to transcriptional repression, not the separate CHD4 DNA-damage buffering mechanism. Intermediates: CHD4-dependent chromatin architecture maintenance; suppression of spontaneous DNA damage
Transcription-Coupled R-loop Accumulation -> Context-Dependent BRCA1 Repair Impairment INDIRECT KNOWN INTERMEDIATES Transcription-associated BRCA1 retention can impair repair availability in the tested cellular context. Intermediates: BRCA1 association with elongating transcription machinery
DHX9 Sequestration During Topoisomerase Stress -> Transcription-Coupled R-loop Accumulation DIRECT DHX9 sequestration prevents resolution of TOP1-poison-induced R-loops and increases replication stress.
USP1-Survivin Stress Buffering -> Tumor Cell Proliferation and Survival INDIRECT KNOWN INTERMEDIATES USP1-dependent survivin stabilization suppresses stress-associated apoptosis. Intermediates: survivin stabilization
SLFN11-Loss-Associated Lipid Remodeling -> Tumor Cell Proliferation and Survival INDIRECT UNKNOWN INTERMEDIATES Metabolic adaptation can support survival under genotoxic therapy in SLFN11-deficient cellular models.
PARP1-Supported Fusion Transcription -> GGAA Microsatellite Enhancer Reprogramming INDIRECT UNKNOWN INTERMEDIATES PARP1 supports the broader fusion transcriptional program; a specific requirement at every GGAA enhancer has not been demonstrated.
Deep research
OpenScientist citations 33 citations 2026-05-28T13:31:43.663508
Show evidence (3 references)
PMID:29513652 SUPPORT In Vitro
"Here we show that Ewing sarcoma cells display alterations in regulation of damage-induced transcription, accumulation of R-loops and increased replication stress."
Supports R-loop accumulation and replication stress downstream of EWS-FLI1 activity.
PMID:40721661 SUPPORT In Vitro
"We discovered that EWS::FLI1 prevents the resolution of R-loops induced by these drugs via sequestering DHX9 helicase, ultimately resulting in R-loop accumulation, replication stress, and genome instability."
Supports the DHX9-dependent R-loop arm of the vulnerability model.
PMID:25779942 SUPPORT In Vitro
"RESULTS: EWS-FLI1 binds near the transcription start site of SLFN11 promoter and acts as a positive regulator of SLFN11 expression in Ewing sarcoma cells."
Supports direct EWS-FLI1 activation of SLFN11 within this vulnerability model.
STAG2/cohesin-modified high-risk enhancer model
cohesin_modified_high_risk_model EMERGING
Evidence balance 4 support
STAG2 loss modifies fusion-dependent and independent chromatin contacts, PRC2 regulation and metastatic behavior. Repeat-class redistribution and selective multimeric enhancer amplification are supported by one recent perturbation study; earlier chromatin-contact studies are related but not exact independent replications. Prognostic associations depend on cohort and assay. COG diagnostic protein-loss/EFS data and Japanese sequencing/post-profiling-OS data measure different exposures and endpoints; the Japanese cohort had only three STAG2-mutant tumors. Their difference does not demonstrate an ancestry-specific mechanism or refute the COG association.
Pathograph links
STAG2-Modified Enhancer State -> GGAA Microsatellite Enhancer Reprogramming DIRECT STAG2/cohesin status changes enhancer-promoter communication at long EWS-FLI1-bound GGAA repeats and rewires enhancer output.
STAG2-Modified Enhancer State -> Metastatic Disease INDIRECT KNOWN INTERMEDIATES STAG2 loss can promote an aggressive, metastasis-prone transcriptional state. Intermediates: altered enhancer-promoter contacts; PRC2 derepression; migratory and neurodevelopmental program rewiring
Deep research
OpenScientist citations 32 citations 2026-05-28T14:12:55.507949
Show evidence (4 references)
PMID:41950086 SUPPORT In Vitro
"Together, these findings reveal that STAG2 loss reprograms, rather than globally attenuates, EWS-FLI1 function, amplifying a high-risk oncogenic transcriptional state in Ewing sarcoma."
Supports the STAG2-modified high-risk enhancer model.
PMID:39487368 SUPPORT In Vitro
"Subsequent genomic profiling and high-resolution chromatin interaction data from Capture Hi-C indicated that cohesin-STAG2 facilitates communication between EWS::FLI1-bound long GGAA repeats, presumably acting as neoenhancers, and their target promoters."
Supports STAG2-dependent enhancer-promoter communication at long GGAA repeats.
PMID:36221002 SUPPORT Human Clinical
"Among patients with localised disease, 5-year event-free survival was 54% (95% CI 34-70%) and 75% (95% CI 63-84%) for patients with STAG2 loss vs. expression (P = 0.0034)."
Supports the high-risk clinical association for STAG2 protein loss.
+ 1 more reference
?

Discussions and Knowledge Gaps

7
Which human progenitor state is truly permissive for EWS-FLI1 transformation, and what chromatin or differentiation-state features distinguish transforming early mesenchymal or neural crest-like cells from non-transforming MSC states?
KNOWLEDGE GAP OPEN gap_ewing_cell_of_origin_context
Attached to
pathophysiology#Permissive Progenitor Cell State pathophysiology#IGF-1/YAP1 Developmental Cooperation pathophysiology#GGAA Microsatellite Germline Susceptibility Architecture pathophysiology#EWS-FLI1 Fusion Oncogene pathophysiology#GGAA Microsatellite Enhancer Reprogramming
Neural crest-derived cells, bone marrow-derived MSCs, pediatric MSCs, adult MSCs, and 2025 embryonic MSC models support overlapping but not identical origin hypotheses. The unresolved mechanism is not simply whether EWS-FLI1 can alter transcription, but which developmental chromatin state lets GGAA enhancer rewiring become transforming rather than toxic, senescent, or differentiation-inducing. IGF-1/YAP1 signaling and germline GGAA repeat architecture now provide concrete cooperating mechanisms, but neither yet defines the full permissive human progenitor state. The fusion can pioneer previously closed GGAA sites, so pre-existing accessibility at all repeats is not a necessary criterion for permissiveness. Adult diagnosis does not by itself date the initiating event. YAP1 opposition to fusion transcription is not equivalent to tumor suppression in established Ewing sarcoma.
Proposed experiments
Isogenic developmental-context EWS-FLI1 induction panel
isogenic stem-cell transformation assay Relation: this experiment is of type this experiment type This experiment is of type isogenic stem-cell transformation assay.
exp_ewing_isogenic_developmental_context_panel
Build an inducible or safe-harbor knock-in EWS-FLI1 panel across hPSC-derived migratory neural crest cells, early mesenchymal progenitors, osteochondral progenitors, pediatric MSCs, and adult MSCs. Measure the same fusion dose and timing across lineages, then compare enhancer activation, differentiation blockade, DNA-damage state, senescence, and xenograft or organoid tumorigenicity.
Model systems
hPSC-derived neural crest and early mesenchymal progenitor panel
Genome-engineered human pluripotent stem cell derivatives with matched EWS-FLI1 induction across candidate Ewing sarcoma cells of origin.
IPSC DERIVED MODEL PMID:41136396 link
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
migratory neural crest cell CL:0000333 Cell Ontology (CL) Relation: this experimental model uses this cell type This experimental model uses migratory neural crest cell (CL:0000333). CL:0000333 is a cell type from the Cell Ontology. early mesenchymal stem cell CL:0000134 Cell Ontology (CL) Relation: this experimental model uses this cell type This experimental model uses early mesenchymal stem cell, annotated with mesenchymal stem cell (CL:0000134). CL:0000134 is a cell type from the Cell Ontology.
Pathograph links
Permissive Progenitor Cell State Tests whether early developmental context permits EWS-FLI1 transformation.
GGAA Microsatellite Enhancer Reprogramming Measures whether the same fusion activates different GGAA enhancer programs by cell state.
Perturbations
Inducible EWS-FLI1 expression
pathophysiology#EWS-FLI1 Fusion Oncogene
Express matched EWS-FLI1 at controlled dose and timing across candidate progenitor states.
EWSR1 hgnc:3508 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets EWSR1 (hgnc:3508). hgnc:3508 is a gene from the HUGO Gene Nomenclature Committee. FLI1 hgnc:3749 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets FLI1 (hgnc:3749). hgnc:3749 is a gene from the HUGO Gene Nomenclature Committee.
Pubertal IGF-1/YAP1 modulation
pathophysiology#IGF-1/YAP1 Developmental Cooperation
Add pubertal-range IGF-1 exposure and YAP1/TEAD inhibition or knockout arms to determine whether the cooperating signal is conserved in human progenitors.
IGF1 hgnc:5464 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets IGF1 (hgnc:5464). hgnc:5464 is a gene from the HUGO Gene Nomenclature Committee. YAP1 hgnc:16262 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets YAP1 (hgnc:16262). hgnc:16262 is a gene from the HUGO Gene Nomenclature Committee.
Readouts
GGAA enhancer activation by developmental state
pathophysiology#GGAA Microsatellite Enhancer Reprogramming
Compare EWS-FLI1 occupancy, chromatin accessibility, and H3K27ac gain at endogenous GGAA microsatellites.
chromatin remodeling GO:0006338 Gene Ontology (GO) Relation: this readout reports on this biological process This readout reports on chromatin remodeling (GO:0006338). GO:0006338 is a biological process from the Gene Ontology.
single-cell ATAC-seq Relation: this readout is measured by this assay This readout is measured by single-cell ATAC-seq. CUT&Tag Relation: this readout is measured by this assay This readout is measured by CUT&Tag. single-cell RNA-seq Relation: this readout is measured by this assay This readout is measured by single-cell RNA-seq.
Direction: POSITIVE
Transformation and differentiation blockade
pathophysiology#Blocked Differentiation
Measure loss of mesenchymal/osteochondral differentiation capacity, acquisition of Ewing-like transcription, senescence avoidance, and tumor formation in permissive contexts.
mesenchymal cell differentiation GO:0048762 Gene Ontology (GO) Relation: this readout reports on this biological process This readout reports on mesenchymal cell differentiation (GO:0048762). GO:0048762 is a biological process from the Gene Ontology.
differentiation assay Relation: this readout is measured by this assay This readout is measured by differentiation assay. xenograft tumorigenicity assay Relation: this readout is measured by this assay This readout is measured by xenograft tumorigenicity assay.
Direction: NEGATIVE
Controls
Isogenic uninduced progenitor controls
Same genetic background and differentiation state without EWS-FLI1 induction.
Nonpermissive adult MSC comparator
Mature MSC context expected to show incomplete transformation or toxicity.
Fusion knockdown or degron rescue
Acute EWS-FLI1 withdrawal after Ewing-like state acquisition.
Decision criterion
The cell-of-origin model is prioritized when a specific progenitor state reproducibly shows EWS-FLI1-dependent GGAA enhancer activation, Ewing-like core regulatory circuitry, differentiation blockade, and tumorigenicity while closely related states fail one or more of those criteria. Do not require every successful enhancer to be open before fusion expression: measure both baseline and induced accessibility. Distinguish developmental transformation from maintenance and growth of established tumors.
Would support
pathophysiology#Permissive Progenitor Cell State pathophysiology#IGF-1/YAP1 Developmental Cooperation pathophysiology#GGAA Microsatellite Enhancer Reprogramming pathophysiology#Blocked Differentiation
Would refute
pathophysiology#Permissive Progenitor Cell State
Show evidence (2 references)
PMID:41136396 SUPPORT In Vitro
"Here we show that EWS::FLI1 expression in human embryonic mesenchymal stem cells (heMSCs) results in the acquisition of an ES transcriptome, with the oncogene not preferentially binding to gene promoters, but to intronic and intergenic microsatellites."
Supports the feasibility and rationale for testing early human mesenchymal contexts.
PMID:21559395 SUPPORT In Vitro
"Importantly, whole genome expression profiling studies revealed that the molecular signature of established ESFT is more similar to hNCSC than any other normal tissue, including MSC, indicating that maintenance or reactivation of the NCSC program is a feature of ESFT pathogenesis."
Supports including neural crest-derived progenitors in the comparative panel.
Show evidence (3 references)
PMID:41136396 SUPPORT In Vitro
"Ewing sarcoma (ES) is an aggressive bone and soft tissue neoplasm characterized by EWSR::ETS rearrangements whose cellular origin remains unclear."
Directly states the knowledge gap.
PMID:40080499 SUPPORT Model Organism
"We report that transient exposure to IGF-1 concentrations mimicking serum levels during puberty reprograms limb-derived mesenchymal cells of EWS::FLI1-mutant mice to stable transformation and tumorigenicity."
Supports adding IGF-1/YAP1 as a concrete cooperating mechanism that still needs human validation.
PMID:36787739 SUPPORT Human Clinical
"We identified 50 microsatellite alleles at 6p25.1 and observed that EwS-affected individuals had longer alleles (>135 bp) with more GGAA repeats."
Supports inherited GGAA architecture as part of the permissive-context gap.
What GGAA microsatellite grammar and cofactor context make EWS-FLI1 binding oncogenic, and why do ETV6, BAF, and STAG2/cohesin perturbations produce different enhancer and differentiation outcomes?
KNOWLEDGE GAP OPEN gap_ewing_ggaa_enhancer_grammar
Attached to
pathophysiology#EWS-FLI1 Chromatin Hub Dynamics pathophysiology#BAF Complex Retargeting pathophysiology#GGAA Microsatellite Enhancer Reprogramming pathophysiology#ETV6 GGAA Counter-Regulation pathophysiology#GGAA Microsatellite Germline Susceptibility Architecture pathophysiology#STAG2-Modified Enhancer State
EWS-FLI1 binds GGAA repeats, but binding alone does not explain why some microsatellites become oncogenic enhancers, why germline repeat length at EGR2 and RREB1 changes susceptibility, why ETV6 antagonism can redirect occupancy toward differentiation, or why STAG2 loss selectively amplifies multimeric GGAA enhancer programs. This gap is the enhancer-grammar layer of the pathograph, now spanning DNA sequence, hub dosage, native ETS competition, and cohesin state.
Proposed experiments
Endogenous GGAA enhancer grammar saturation editing
pooled endogenous enhancer saturation editing experiment Relation: this experiment is of type this experiment type This experiment is of type pooled endogenous enhancer saturation editing experiment.
exp_ewing_endogenous_ggaa_saturation_editing
Use multiplex prime/base editing or CRISPR replacement to vary repeat length, repeat purity, flanking ETS motifs, and local chromatin context at endogenous EWS-FLI1-bound GGAA microsatellites. Combine these edits with acute BAF, ETV6, and STAG2 perturbations to quantify how enhancer grammar and cofactor state determine transcriptional output.
Model systems
Ewing sarcoma cell-line and early progenitor enhancer-editing panel
EWS-FLI1-positive Ewing sarcoma cell lines plus permissive progenitor models with editable endogenous GGAA microsatellite enhancers.
CELL LINE PMID:41950086 link
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Pathograph links
GGAA Microsatellite Enhancer Reprogramming Tests enhancer sequence grammar required for de novo enhancer function.
STAG2-Modified Enhancer State Tests how STAG2 loss changes enhancer grammar dependence.
Perturbations
GGAA microsatellite sequence editing
pathophysiology#GGAA Microsatellite Enhancer Reprogramming
Edit endogenous EWS-FLI1-bound GGAA repeats across short, intermediate, and long repeat classes, including susceptibility alleles at EGR2 and RREB1.
EGR2 hgnc:3239 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets EGR2 (hgnc:3239). hgnc:3239 is a gene from the HUGO Gene Nomenclature Committee. RREB1 hgnc:10449 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets RREB1 (hgnc:10449). hgnc:10449 is a gene from the HUGO Gene Nomenclature Committee.
ETV6, STAG2, and BAF cofactor perturbation
pathophysiology#BAF Complex Retargeting
Combine enhancer edits with degron, CRISPRi, or knockout perturbations of ETV6, STAG2, and BAF complex activity.
ETV6 hgnc:3495 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets ETV6 (hgnc:3495). hgnc:3495 is a gene from the HUGO Gene Nomenclature Committee. STAG2 hgnc:11355 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets STAG2 (hgnc:11355). hgnc:11355 is a gene from the HUGO Gene Nomenclature Committee.
Readouts
Enhancer occupancy and activity
pathophysiology#GGAA Microsatellite Enhancer Reprogramming
Quantify EWS-FLI1 occupancy, BAF recruitment, chromatin accessibility, H3K27ac, enhancer-promoter contact, and target-gene transcription for each edited enhancer allele.
regulation of gene expression GO:0010468 Gene Ontology (GO) Relation: this readout reports on this biological process This readout reports on regulation of gene expression (GO:0010468). GO:0010468 is a biological process from the Gene Ontology.
CUT&Tag Relation: this readout is measured by this assay This readout is measured by CUT&Tag. ATAC-seq Relation: this readout is measured by this assay This readout is measured by ATAC-seq. HiChIP Relation: this readout is measured by this assay This readout is measured by HiChIP. single-cell RNA-seq Relation: this readout is measured by this assay This readout is measured by single-cell RNA-seq.
Direction: POSITIVE
Differentiation versus proliferation outcome
pathophysiology#Core Regulatory Circuitry Activation
Determine whether edited enhancer states reinforce Ewing core regulatory circuitry, drive mesenchymal differentiation, or reduce tumor cell growth.
cell population proliferation GO:0008283 Gene Ontology (GO) Relation: this readout reports on this biological process This readout reports on cell population proliferation (GO:0008283). GO:0008283 is a biological process from the Gene Ontology.
pooled growth screen Relation: this readout is measured by this assay This readout is measured by pooled growth screen. differentiation marker profiling Relation: this readout is measured by this assay This readout is measured by differentiation marker profiling.
Direction: POSITIVE
Controls
Synonymous non-GGAA neutral edits
Editing controls matched for guide delivery and repair outcome.
EWS-FLI1 degron withdrawal
Fusion-dependence control for edited enhancer activity.
Decision criterion
A causal enhancer-grammar rule is supported when endogenous repeat edits produce predictable EWS-FLI1 occupancy, BAF recruitment, enhancer-promoter contact, and transcriptional changes that reverse with fusion withdrawal and change coherently under ETV6 or STAG2 perturbation.
Would support
pathophysiology#GGAA Microsatellite Enhancer Reprogramming pathophysiology#BAF Complex Retargeting pathophysiology#STAG2-Modified Enhancer State
Would refute
pathophysiology#STAG2-Modified Enhancer State
Show evidence (2 references)
PMID:36658219 SUPPORT In Vitro
"Using biochemical assays and epigenomics, we show that ETV6 competes with EWS-FLI1 for binding to select DNA elements enriched for short GGAA repeat sequences."
Supports testing ETV6 as an enhancer-grammar modifier.
PMID:41950086 SUPPORT In Vitro
"These reprogrammed sites show changes in both chromatin accessibility and H3K27ac, leading to selective amplification of EWS-FLI1 activity at multimeric microsatellite enhancers."
Supports testing repeat-length-dependent STAG2 effects.
Show evidence (4 references)
PMID:25453903 SUPPORT In Vitro
"At GGAA repeat elements, which lack evolutionary conservation and regulatory potential in other cell types, EWS-FLI1 multimers induce chromatin opening and create de novo enhancers that physically interact with target promoters."
Establishes the enhancer phenomenon whose causal sequence rules remain unresolved.
PMID:26214589 SUPPORT In Vitro
"At rs79965208, the A risk allele connected adjacent GGAA repeats by converting an interspaced GGAT motif into a GGAA motif, thereby increasing the number of consecutive GGAA motifs and thus the EWSR1-FLI1-dependent enhancer activity of this sequence, with epigenetic characteristics of an active..."
Supports germline repeat architecture as a testable enhancer-grammar variable.
PMID:36787739 SUPPORT Human Clinical
"We identified 50 microsatellite alleles at 6p25.1 and observed that EwS-affected individuals had longer alleles (>135 bp) with more GGAA repeats."
Supports long-read resolution of germline GGAA alleles as part of the enhancer-grammar gap.
+ 1 more reference
Which EWS-FLI1-dependent chromatin-accessibility states are causal tumor dependencies rather than passenger signatures, and can an automated high-throughput chromatin assay distinguish therapeutically useful chromatin reversal from nonspecific cytotoxicity?
KNOWLEDGE GAP OPEN gap_ewing_chromatin_reversal_screen
Attached to
pathophysiology#EWS-FLI1 Fusion Oncogene pathophysiology#EWS-FLI1 Chromatin Hub Dynamics pathophysiology#GGAA Microsatellite Enhancer Reprogramming pathophysiology#ETV6 GGAA Counter-Regulation pathophysiology#NuRD-LSD1 Transcriptional Repression pathophysiology#Core Regulatory Circuitry Activation
Ian Davis lab work showed that EWS-FLI1 retargets chromatin, creates nucleosome-depleted enhancer states, and can be assayed with automated high-throughput FAIRE. However, the therapeutic interpretation remains unresolved: a compound or degrader that reduces an Ewing chromatin signature could act by direct fusion-pathway reversal, by ETV6 or NuRD/HDAC/LSD1 modifier biology, by reduced EWS-FLI1 expression, or by general toxicity. A mechanism-resolved chromatin perturbation screen would convert this chromatin phenotype into a decision rule for prioritizing causal nodes and cloud-lab-ready follow-up experiments.
Proposed experiments
Automated EWS-FLI1 chromatin-reversal perturbation screen
automated high-throughput chromatin-accessibility perturbation screen Relation: this experiment is of type this experiment type This experiment is of type automated high-throughput chromatin-accessibility perturbation screen.
exp_ewing_automated_chromatin_reversal_screen
Run an automated plate-based chromatin-accessibility screen in Ewing sarcoma models using HT-FAIRE, ATAC-qPCR, or low-input ATAC-seq readouts at sentinel EWS-FLI1 GGAA enhancers, ETV6-competed short GGAA elements, and repressed mesenchymal enhancers. Screen annotated epigenetic compounds, targeted degraders, kinase/chemical-probe libraries, and EWS-FLI1 or ETV6 perturbation controls, then triage hits by matched viability, fusion expression, enhancer activity, and transcriptional rescue.
Model systems
Ewing sarcoma chromatin-accessibility screening panel
EWS-FLI1-positive Ewing sarcoma cell lines with sentinel GGAA enhancers and matched orthogonal chromatin, expression, and viability assays.
CELL LINE PMID:26929321 link
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Pathograph links
GGAA Microsatellite Enhancer Reprogramming Measures whether perturbations reverse fusion-dependent nucleosome depletion at GGAA enhancers.
ETV6 GGAA Counter-Regulation Tests whether ETV6-directed perturbation produces a separable short-GGAA enhancer state.
NuRD-LSD1 Transcriptional Repression Tests whether chromatin-repressive modifiers drive rescue of lineage or tumor-suppressive enhancers.
Perturbations
Epigenetic compound and degrader library
pathophysiology#GGAA Microsatellite Enhancer Reprogramming
Apply annotated epigenetic inhibitors, targeted degraders, and chemical probe libraries with dose and time gradients suitable for automated liquid handling.
EWS-FLI1 and ETV6 perturbation controls
pathophysiology#EWS-FLI1 Fusion Oncogene
Include acute fusion knockdown or degron withdrawal, ETV6 degradation or knockdown, and vehicle controls to calibrate chromatin-reversal directionality.
EWSR1 hgnc:3508 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets EWSR1 (hgnc:3508). hgnc:3508 is a gene from the HUGO Gene Nomenclature Committee. FLI1 hgnc:3749 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets FLI1 (hgnc:3749). hgnc:3749 is a gene from the HUGO Gene Nomenclature Committee. ETV6 hgnc:3495 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets ETV6 (hgnc:3495). hgnc:3495 is a gene from the HUGO Gene Nomenclature Committee.
Readouts
Sentinel chromatin-accessibility reversal
pathophysiology#GGAA Microsatellite Enhancer Reprogramming
Quantify accessibility at EWS-FLI1-activated GGAA enhancers, ETV6- competed short GGAA elements, and fusion-repressed mesenchymal enhancers.
chromatin remodeling GO:0006338 Gene Ontology (GO) Relation: this readout reports on this biological process This readout reports on chromatin remodeling (GO:0006338). GO:0006338 is a biological process from the Gene Ontology.
HT-FAIRE Relation: this readout is measured by this assay This readout is measured by HT-FAIRE. ATAC-qPCR Relation: this readout is measured by this assay This readout is measured by ATAC-qPCR. low-input ATAC-seq Relation: this readout is measured by this assay This readout is measured by low-input ATAC-seq.
Direction: NEGATIVE
Mechanism-resolved transcriptional rescue
pathophysiology#Core Regulatory Circuitry Activation
Pair chromatin hits with targeted RNA-seq or Perturb-seq to determine whether KLF15/TCF4/NKX2-2 circuitry, mesenchymal differentiation genes, EWS-FLI1 abundance, or generic stress pathways explain the response.
regulation of gene expression GO:0010468 Gene Ontology (GO) Relation: this readout reports on this biological process This readout reports on regulation of gene expression (GO:0010468). GO:0010468 is a biological process from the Gene Ontology.
targeted RNA-seq Relation: this readout is measured by this assay This readout is measured by targeted RNA-seq. Perturb-seq Relation: this readout is measured by this assay This readout is measured by Perturb-seq. immunoblotting Relation: this readout is measured by this assay This readout is measured by immunoblotting.
Direction: NEGATIVE
Growth and toxicity separation
pathophysiology#Tumor Cell Proliferation and Survival
Measure viability, apoptosis, and clonogenic growth in the same dose and time grid to separate mechanism-specific chromatin reversal from nonspecific cytotoxicity.
cell population proliferation GO:0008283 Gene Ontology (GO) Relation: this readout reports on this biological process This readout reports on cell population proliferation (GO:0008283). GO:0008283 is a biological process from the Gene Ontology.
viability assay Relation: this readout is measured by this assay This readout is measured by viability assay. apoptosis assay Relation: this readout is measured by this assay This readout is measured by apoptosis assay. clonogenic survival assay Relation: this readout is measured by this assay This readout is measured by clonogenic survival assay.
Direction: NEGATIVE
Controls
EWS-FLI1 knockdown positive control
Calibrates the expected chromatin-accessibility direction for true fusion-pathway reversal.
Short-exposure viability control
Flags compounds whose chromatin signal is secondary to acute cell loss or global toxicity.
Non-Ewing sarcoma comparator cells
Tests whether hits reverse a Ewing-specific chromatin state rather than general chromatin accessibility.
Decision criterion
A chromatin-reversal hit is prioritized when it reproducibly shifts sentinel EWS-FLI1 accessibility and transcription toward the fusion- withdrawal state at concentrations and times that precede broad cytotoxicity, and when the response maps to a declared mechanism node such as ETV6 competition, NuRD/HDAC/LSD1 repression, or EWS-FLI1 dosage.
Would support
pathophysiology#GGAA Microsatellite Enhancer Reprogramming pathophysiology#ETV6 GGAA Counter-Regulation pathophysiology#NuRD-LSD1 Transcriptional Repression pathophysiology#Tumor Cell Proliferation and Survival
Would refute
pathophysiology#GGAA Microsatellite Enhancer Reprogramming pathophysiology#ETV6 GGAA Counter-Regulation
Show evidence (3 references)
PMID:26929321 SUPPORT In Vitro
"To explore whether chromatin accessibility could serve as a platform for small molecule screening, we adapted formaldehyde-assisted isolation of regulatory elements (FAIRE), a chemical method to enrich for nucleosome-depleted genomic regions, as a high-throughput, automated assay."
Supports the feasibility of automated chromatin-accessibility screening in this disease context.
PMID:26929321 SUPPORT In Vitro
"After demonstrating the validity and robustness of this approach, we applied this method to screen an epigenetically targeted small molecule library by evaluating regions of aberrant nucleosome depletion mediated by EWSR1-FLI1, the chimeric transcription factor critical for the bone and soft..."
Supports using EWS-FLI1-dependent accessibility regions as the primary assay signal.
+ 1 more reference
Show evidence (2 references)
PMID:22086061 SUPPORT In Vitro
"Thus, the EWS-FLI chimera acquired chromatin-altering activity, leading to mistargeting, chromatin disruption, and ultimately, transcriptional dysregulation."
Establishes the EWS-FLI1 chromatin-altering phenomenon that motivates the knowledge gap.
PMID:26929321 SUPPORT In Vitro
"Capitalizing on precise differences in chromatin accessibility for drug discovery efforts offers significant advantages because it does not depend on the a priori selection of a single molecular target and may detect novel biologically relevant pathways."
Supports chromatin-signature screening as a target-agnostic route to mechanism discovery.
Which EWS-FLI1-induced DHX9/R-loop, SLFN11 fork-blocking, BRCA1, STAG2, and USP1-survivin states determine whether replication stress causes chemosensitivity, PARP/USP1/ATR inhibitor vulnerability, or survival and relapse?
KNOWLEDGE GAP OPEN gap_ewing_replication_stress_response
Attached to
pathophysiology#DHX9 Sequestration During Topoisomerase Stress pathophysiology#Transcription-Coupled R-loop Accumulation pathophysiology#STAG2-Modified Enhancer State pathophysiology#Tumor Cell Proliferation and Survival treatments#Neoadjuvant Chemotherapy
Ewing sarcoma is sensitive to genotoxic chemotherapy, and EWS-FLI1 creates R-loops, replication stress, SLFN11-dependent fork blocking, and homologous-recombination defects. However, high-risk and relapsed tumors survive therapy, and it is not yet clear which molecular stress-state measurements predict response to PARP, ATR, USP1, or chemotherapy combinations.
Proposed experiments
Replication-stress pharmacodynamic response panel
perturbation-response pharmacodynamic experiment Relation: this experiment is of type this experiment type This experiment is of type perturbation-response pharmacodynamic experiment.
exp_ewing_replication_stress_pharmacodynamic_panel
Profile matched diagnosis-relapse samples, patient-derived cultures, and Ewing sarcoma cell lines under etoposide, doxorubicin, PARP inhibition, USP1 inhibition, and combinations. Perturb EWS-FLI1, DHX9, SLFN11, BRCA1, USP1, and BIRC5 to separate primary fusion-induced stress, fork blocking, and survival adaptation.
Model systems
Matched Ewing sarcoma patient-derived culture and cell-line panel
Human Ewing sarcoma cultures and cell lines stratified by therapy response, STAG2 status, and replication-stress markers.
PRIMARY CELL CULTURE PMID:37478161 link
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Pathograph links
DHX9 Sequestration During Topoisomerase Stress Measures DHX9/R-loop and SLFN11 fork-blocking states under treatment.
Transcription-Coupled R-loop Accumulation Measures R-loops, replication stress, and DNA repair state under treatment.
Perturbations
Genotoxic and targeted stress perturbation
pathophysiology#Transcription-Coupled R-loop Accumulation
Compare standard genotoxic agents with PARP and USP1 inhibition under fusion knockdown or repair/survival gene perturbation.
DHX9 hgnc:2750 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets DHX9 (hgnc:2750). hgnc:2750 is a gene from the HUGO Gene Nomenclature Committee. SLFN11 hgnc:26633 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets SLFN11 (hgnc:26633). hgnc:26633 is a gene from the HUGO Gene Nomenclature Committee. BRCA1 hgnc:1100 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets BRCA1 (hgnc:1100). hgnc:1100 is a gene from the HUGO Gene Nomenclature Committee. USP1 hgnc:12607 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets USP1 (hgnc:12607). hgnc:12607 is a gene from the HUGO Gene Nomenclature Committee. BIRC5 hgnc:593 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets BIRC5 (hgnc:593). hgnc:593 is a gene from the HUGO Gene Nomenclature Committee.
Readouts
R-loop, fork-blocking, and homologous-recombination response
pathophysiology#DHX9 Sequestration During Topoisomerase Stress
Measure R-loop burden, DHX9 occupancy, SLFN11 chromatin recruitment, replication fork stress, gamma-H2AX, RAD51 foci, BRCA1 localization, and transcription-coupled DNA damage after treatment.
double-strand break repair via homologous recombination GO:0000724 Gene Ontology (GO) Relation: this readout reports on this biological process This readout reports on double-strand break repair via homologous recombination (GO:0000724). GO:0000724 is a biological process from the Gene Ontology.
DRIP-seq Relation: this readout is measured by this assay This readout is measured by DRIP-seq. DNA fiber assay Relation: this readout is measured by this assay This readout is measured by DNA fiber assay. immunofluorescence DNA repair foci assay Relation: this readout is measured by this assay This readout is measured by immunofluorescence DNA repair foci assay.
Direction: NEGATIVE
Cell survival under replication stress
pathophysiology#Tumor Cell Proliferation and Survival
Quantify apoptosis, clonogenic survival, and drug synergy across chemotherapy, PARP inhibition, and USP1 inhibition.
cell population proliferation GO:0008283 Gene Ontology (GO) Relation: this readout reports on this biological process This readout reports on cell population proliferation (GO:0008283). GO:0008283 is a biological process from the Gene Ontology.
clonogenic survival assay Relation: this readout is measured by this assay This readout is measured by clonogenic survival assay. apoptosis assay Relation: this readout is measured by this assay This readout is measured by apoptosis assay.
Direction: NEGATIVE
Controls
EWS-FLI1 knockdown or degron control
Tests whether replication-stress markers are fusion-dependent.
Isogenic USP1 or BIRC5 rescue
Separates USP1-survivin survival adaptation from upstream R-loop burden.
Decision criterion
A predictive stress-state model is supported when baseline or early treatment-induced R-loop/BRCA1/USP1-survivin readouts reproducibly predict death, survival, or drug synergy across independent patient-derived models and are reversed by the corresponding genetic rescue or withdrawal.
Would support
pathophysiology#DHX9 Sequestration During Topoisomerase Stress pathophysiology#Transcription-Coupled R-loop Accumulation pathophysiology#Tumor Cell Proliferation and Survival
Would refute
pathophysiology#Transcription-Coupled R-loop Accumulation
Show evidence (4 references)
PMID:29513652 SUPPORT In Vitro
"Ewing sarcoma is highly sensitive to genotoxic agents such as etoposide, but the underlying molecular basis of this sensitivity is unclear."
Supports the unresolved response-mechanism framing.
PMID:37478161 SUPPORT In Vitro
"Notably, USP1 inhibition sensitizes cells to doxorubicin and etoposide treatment."
Supports USP1 as a testable stress-survival target.
+ 2 more references
Show evidence (2 references)
PMID:37478161 SUPPORT In Vitro
"The mechanism by which EWS cells override activation of apoptosis or cellular senescence in response to increased replication stress is not known."
Directly states the survival-under-replication-stress knowledge gap.
PMID:40721661 SUPPORT In Vitro
"In turn, excessive DHX9 or reduced EWS::FLI1 levels render EwS cells resistant to the active metabolite of irinotecan (SN-38) independent of proliferation and global transcription rates."
Supports unresolved resistance prediction involving DHX9 and fusion dosage.
In STAG2-altered Ewing sarcoma, which causal arm best explains high-risk disease: multimeric GGAA enhancer amplification, PRC2/CTCF chromatin rewiring, replication-fork repair vulnerability, or a context-specific combination of these mechanisms?
KNOWLEDGE GAP OPEN gap_ewing_stag2_cohesin_high_risk_mechanism
Attached to
pathophysiology#STAG2-Modified Enhancer State pathophysiology#GGAA Microsatellite Enhancer Reprogramming pathophysiology#DHX9 Sequestration During Topoisomerase Stress pathophysiology#Transcription-Coupled R-loop Accumulation phenotypes#Metastatic Disease
The reviewed literature supports that STAG2 loss reshapes GGAA enhancer-promoter contacts and is clinically adverse, but the mechanism is not a single clean edge. EWS-FLI1-dependent long-GGAA contacts, EWS-FLI1- independent CTCF changes, PRC2 derepression, TP53 co-alteration, and replication-fork stress could each contribute differently across cohorts, ancestry backgrounds, and treatment states. Protein loss, mutation, enhancer occupancy and treatment sensitivity are distinct measurements. COG diagnostic IHC/EFS and Japanese post-profiling mutation/OS results do not establish an ancestry effect. NR0B1 repeats were longer in African than European healthy subjects in PMID:22749036, the opposite of the OpenScientist cohesin report; no Japanese-repeat mechanism follows from that study. STAG2-dependent fork/HR findings from broader cancer models justify matched Ewing experiments, not a confirmed clinical predictive biomarker.
Proposed experiments
STAG2-stratified primary-tumor chromatin and DDR atlas
STAG2-stratified multi-omic mechanism atlas Relation: this experiment is of type this experiment type This experiment is of type STAG2-stratified multi-omic mechanism atlas.
exp_ewing_stag2_primary_tumor_chromatin_ddr_atlas
Profile STAG2-positive and STAG2-negative primary and relapse Ewing sarcoma specimens with matched WGS, long-read GGAA microsatellite typing, RNA-seq, ATAC-seq or CUT&Tag, H3K27ac/H3K27me3, CTCF/cohesin occupancy, and DNA-damage response markers. Pair the tumor atlas with isogenic STAG2 rescue or knockout in Ewing sarcoma cultures to separate enhancer, PRC2/CTCF, and replication-stress arms.
Model systems
STAG2-positive and STAG2-negative Ewing sarcoma tumor cohort
Banked diagnostic and relapse Ewing sarcoma tumors with STAG2 protein status, mutation calls, clinical outcome, and ancestry-aware GGAA repeat genotyping.
OTHER PMID:36221002 link
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Pathograph links
STAG2-Modified Enhancer State Tests whether STAG2 loss produces the same high-risk chromatin state in primary tumors.
GGAA Microsatellite Enhancer Reprogramming Measures multimeric GGAA enhancer amplification and enhancer-promoter contact strength.
Transcription-Coupled R-loop Accumulation Measures whether STAG2 loss adds fork and repair stress to the fusion-driven DDR state.
Perturbations
STAG2 rescue or knockout
pathophysiology#STAG2-Modified Enhancer State
Restore STAG2 in STAG2-deficient Ewing sarcoma models and remove STAG2 in matched STAG2-proficient models while stratifying by TP53 status.
STAG2 hgnc:11355 HUGO Gene Nomenclature Committee (hgnc) Relation: this perturbation targets this gene This perturbation targets STAG2 (hgnc:11355). hgnc:11355 is a gene from the HUGO Gene Nomenclature Committee.
Readouts
Enhancer, PRC2, and CTCF arm partition
pathophysiology#STAG2-Modified Enhancer State
Quantify EWS-FLI1 occupancy at short and long GGAA repeats, enhancer-promoter contacts, H3K27ac, H3K27me3, CTCF loops, and neurodevelopmental or migratory target-gene expression.
chromosome organization GO:0051276 Gene Ontology (GO) Relation: this readout reports on this biological process This readout reports on chromosome organization (GO:0051276). GO:0051276 is a biological process from the Gene Ontology.
long-read microsatellite genotyping Relation: this readout is measured by this assay This readout is measured by long-read microsatellite genotyping. Capture Hi-C Relation: this readout is measured by this assay This readout is measured by Capture Hi-C. ATAC-seq Relation: this readout is measured by this assay This readout is measured by ATAC-seq. CUT&Tag Relation: this readout is measured by this assay This readout is measured by CUT&Tag.
Direction: POSITIVE
Replication-fork and repair-stress response
pathophysiology#Transcription-Coupled R-loop Accumulation
Measure DNA fiber fork progression, gamma-H2AX, RAD51 foci, PARP/ATR inhibitor response, and chemotherapy response by STAG2 state.
DNA replication GO:0006260 Gene Ontology (GO) Relation: this readout reports on this biological process This readout reports on DNA replication (GO:0006260). GO:0006260 is a biological process from the Gene Ontology.
DNA fiber assay Relation: this readout is measured by this assay This readout is measured by DNA fiber assay. immunofluorescence DNA repair foci assay Relation: this readout is measured by this assay This readout is measured by immunofluorescence DNA repair foci assay. drug-response matrix Relation: this readout is measured by this assay This readout is measured by drug-response matrix.
Direction: NEGATIVE
Controls
STAG2-wild-type matched tumors
Stage-, site-, age-, and ancestry-matched tumors retaining STAG2 expression.
Isogenic rescue controls
STAG2 restoration or knockout controls that separate STAG2 effects from cell-line background.
Decision criterion
The STAG2 high-risk model is strengthened if STAG2-negative primary tumors reproduce long-GGAA enhancer amplification and if isogenic rescue reverses the predicted enhancer, PRC2/CTCF, or DDR arm. A single dominant arm would be prioritized only if it predicts clinical outcome and drug response better than the alternatives.
Would support
pathophysiology#STAG2-Modified Enhancer State pathophysiology#GGAA Microsatellite Enhancer Reprogramming pathophysiology#Transcription-Coupled R-loop Accumulation
Would refute
pathophysiology#STAG2-Modified Enhancer State
Show evidence (2 references)
PMID:39487368 SUPPORT In Vitro
"Subsequent genomic profiling and high-resolution chromatin interaction data from Capture Hi-C indicated that cohesin-STAG2 facilitates communication between EWS::FLI1-bound long GGAA repeats, presumably acting as neoenhancers, and their target promoters."
Supports measuring STAG2-dependent long-GGAA enhancer-promoter contacts.
PMID:36221002 SUPPORT Human Clinical
"CONCLUSION: STAG2 loss of expression is identified in a population of patients without identifiable STAG2 mutations and carries a poor prognosis."
Supports the need for primary-tumor clinical stratification by STAG2 loss.
Show evidence (5 references)
PMID:39487368 SUPPORT In Vitro
"Changes in CTCF-dependent chromatin contacts involving signature genes, unrelated to EWS::FLI1 binding, were also identified."
Supports the unresolved CTCF arm of the STAG2 mechanism.
PMID:36221002 SUPPORT Human Clinical
"CONCLUSION: STAG2 loss of expression is identified in a population of patients without identifiable STAG2 mutations and carries a poor prognosis."
Supports STAG2 protein loss as a clinically meaningful high-risk state.
PMID:25223734 SUPPORT Human Clinical
"Strikingly, STAG2 mutations and CDKN2A deletions were mutually exclusive, as confirmed in Ewing sarcoma cell lines."
Supports the need to stratify STAG2 effects against other high-risk genomic routes.
+ 2 more references
By what route does STAG2 loss raise EWS-FLI1 protein abundance, and does that increase feed back into the enhancer phenotype rather than merely accompanying it?
KNOWLEDGE GAP OPEN gap_ewing_stag2_loss_to_fusion_protein_abundance
Attached to
pathophysiology#STAG2-Modified Enhancer State pathophysiology#EWS-FLI1 Dosage and State Plasticity pathophysiology#GGAA Microsatellite Enhancer Reprogramming
This entry curates the two ends of this link and nothing in between. The multiomic STAG2 loss-of-function study reports increased EWS-FLI1 protein abundance alongside the redistribution of fusion binding from short toward multimeric GGAA repeats, and does not account for the abundance change. Separately, the dosage node holds a regulated turnover pathway and a window whose output is non-monotonic in both directions, with TRIM8-mediated degradation as the curated mechanism keeping fusion protein within it. No study has asked whether STAG2 loss acts on that pathway. This matters for interpretation rather than completeness: if the protein rise is causal, the enhancer redistribution reported in STAG2-null cells is partly a dose effect operating through the curated window rather than a purely architectural consequence of losing cohesin-STAG2, and the two published mechanisms would not be independent. Deubiquitination is the obvious place to look, since USP19 stabilizes the fusion and its depletion lowers fusion levels, giving a manipulable step rather than an open-ended search. Measuring fusion ubiquitination, half-life, and USP19 and TRIM8 levels in isogenic STAG2 wild-type and null pairs, then holding fusion dose constant with a degron while removing STAG2, would separate the two.
Show evidence (3 references)
PMID:41950086 SUPPORT In Vitro
"Despite increased EWS-FLI1 protein abundance, STAG2 loss eliminates over 40% of EWS-FLI1 binding sites"
Records the unexplained protein-abundance increase that motivates this gap, and shows it running opposite to the loss of binding sites, which is why the two cannot be read as one effect.
PMID:30700749 SUPPORT In Vitro
"Constant EWS-FLI1 protein turnover is regulated by the ubiquitin proteasome system."
Establishes that a defined turnover pathway exists to be tested as the route for the STAG2-associated protein increase.
PMID:30700749 SUPPORT In Vitro
"Depletion of USP19 resulted in diminished EWS-FLI1 protein levels and, vice versa, upregulation of active USP19 stabilized the fusion protein."
Identifies a specific, manipulable step in that turnover pathway, which is what makes the proposed test concrete. It does not itself connect USP19 to STAG2.
Do the Ewing sarcomas that present after age 40, which are predominantly extraskeletal and carry markedly worse survival, arise from the same permissive progenitor state as pediatric tumors, or is the developmental model narrower in scope than the entry implies?
KNOWLEDGE GAP OPEN gap_ewing_adult_onset_extraskeletal_origin
Attached to
pathophysiology#Permissive Progenitor Cell State pathophysiology#IGF-1/YAP1 Developmental Cooperation has_subtypes#Extraosseous Ewing Sarcoma
The permissive-progenitor and IGF-1/YAP1 mechanisms curated here are both anchored to a developmental window: an early mesenchymal or neural crest-derived chromatin state, and a pubertal growth-factor signal that fits the adolescent incidence peak. Registry data show the disease extends well past that window. In a SEER cohort of 2,780 patients, 383 were diagnosed at 40 years or older, and those patients were roughly twice as likely to have extraskeletal primaries and had substantially worse survival. This is a question about cell of origin, not about age at initiation: a late diagnosis does not date the initiating event, so persistence of a permissive progenitor and a genuinely different route are both live. The registry cohort also predates routine molecular confirmation, and the source itself notes that the higher rate of soft-tissue and PNET-coded tumors in older patients may reflect clinical naming rather than tumor biology, so part of the age difference may be classification artifact. That confound is itself part of what needs resolving. Age-stratified DNA methylation and single-cell profiling of molecularly confirmed adult-onset versus pediatric tumors would settle whether the curated developmental mechanism covers them.
Show evidence (4 references)
PMID:22959474 SUPPORT Human Clinical
"2780 patients were identified; including 383 patients diagnosed ≥40 years"
Establishes that adult-onset disease is a substantial minority rather than a negligible tail.
PMID:22959474 SUPPORT Human Clinical
"Patients ≥40 years of age were more likely to have extra-skeletal tumors (66.1% vs. 31.7%; p < 0.001)"
Shows the adult-onset group differs in primary site, which is the observation that makes a shared developmental origin an open question rather than an assumption.
PMID:22959474 SUPPORT Human Clinical
"Five-year survival for those age ≥40 and age <40 were 40.6% and 54.3%, respectively"
Establishes the clinical stakes of resolving whether adult-onset disease shares the curated mechanism.
+ 1 more reference
⚙

Pathophysiology

30
EWS-FLI1 Fusion Oncogene
The t(11;22)(q24;q12) translocation fuses the EWS gene (EWSR1) on chromosome 22 with the FLI1 gene on chromosome 11. The resulting EWS-FLI1 protein functions as an aberrant FET-ETS transcription factor. It is the truncal driver of most Ewing sarcomas, but its oncogenic effect depends on a permissive developmental cell state and on downstream enhancer, transcriptional, metabolic, and DNA damage-response programs.
Canonical EWS-FLI1 fusion enhanceropathy model Transcription-coupled replication stress vulnerability model
early mesenchymal stem cell CL:0000134 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves early mesenchymal stem cell, annotated with mesenchymal stem cell (CL:0000134). CL:0000134 is a cell type from the Cell Ontology. migratory neural crest cell CL:0000333 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves migratory neural crest cell (CL:0000333). CL:0000333 is a cell type from the Cell Ontology.
EWSR1 hgnc:3508 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves EWSR1 (hgnc:3508). hgnc:3508 is a gene from the HUGO Gene Nomenclature Committee. FLI1 hgnc:3749 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves FLI1 (hgnc:3749). hgnc:3749 is a gene from the HUGO Gene Nomenclature Committee.
Genetic context variant_origin: SOMATIC
positive regulation of transcription by RNA polymerase II GO:0045944 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal positive regulation of transcription by RNA polymerase II (GO:0045944). GO:0045944 is a biological process from the Gene Ontology.
Experimental models
Ewing sarcoma tumor organoid model systems ORGANOID Models fusion-positive tumor biology in a 3D non-animal context.
Patient-derived Ewing sarcoma culture panel PRIMARY CELL CULTURE Models EWSR1 fusion-positive tumor state in patient-derived cultures.
Human embryonic mesenchymal stem cell EWS-FLI1 transformation model PRIMARY CELL CULTURE Models EWS-FLI1 oncogene expression in an embryonic human mesenchymal developmental context, with xenograft tumor formation demonstrating transformation capacity.
Downstream
EWS-FLI1 Chromatin Hub Dynamics Low-complexity-domain interactions enable chromatin-associated fusion hubs; endogenous dynamic hub measurements are currently supported by a preprint. Canonical EWS-FLI1 fusion enhanceropathy model
BAF Complex Retargeting The EWSR1-derived low-complexity domain enables EWS-FLI1 to recruit BAF chromatin-remodeling complexes to tumor-specific enhancers. Canonical EWS-FLI1 fusion enhanceropathy model
GGAA Microsatellite Enhancer Reprogramming EWS-FLI1 occupies GGAA microsatellite repeats and canonical ETS sites, creating de novo enhancers while repressing other enhancer classes. Canonical EWS-FLI1 fusion enhanceropathy model
NuRD-LSD1 Transcriptional Repression EWS-FLI1 recruits NuRD-associated HDAC and LSD1 activities for transcriptional repression; the separate CHD4 survival dependency does not establish that CHD4 acts through EWS-FLI1 target-gene regulation. Canonical EWS-FLI1 fusion enhanceropathy model
ATF4-Serine-Glycine Metabolic Reprogramming EWS-FLI1 directly activates ATF4 and metabolic stress-response programs. Canonical EWS-FLI1 fusion enhanceropathy model Transcription-coupled replication stress vulnerability model
Transcription-Coupled R-loop Accumulation High-output transcription and defective damage-associated transcriptional control promote R-loop accumulation and replication stress. Transcription-coupled replication stress vulnerability model
DHX9 Sequestration During Topoisomerase Stress In TOP1-poison-treated Ewing cells, EWS-FLI1 binds DHX9 and interferes with resolution of drug-induced R-loops. Transcription-coupled replication stress vulnerability model
EWS-FLI1 Dosage and State Plasticity The fusion protein is subject to dosage control and its abundance changes the transcriptional state. Canonical EWS-FLI1 fusion enhanceropathy model
SLFN11-Dependent Replication Fork Arrest EWS-FLI1 directly activates SLFN11 transcription. Transcription-coupled replication stress vulnerability model
USP1-Survivin Stress Buffering EWS-FLI1 increases USP1 expression and thereby supports survivin-dependent stress tolerance. Transcription-coupled replication stress vulnerability model
Proposed POLQ Splicing and MMEJ Defect Fusion expression perturbs faithful POLQ splicing in the reported cellular models; this preprint-derived edge is provisional. Transcription-coupled replication stress vulnerability model
PARP1-Supported Fusion Transcription Fusion expression maintains PARP1 expression in a reciprocal transcriptional dependency. Transcription-coupled replication stress vulnerability model
EZH2-Associated Differentiation Repression Fusion binding at the EZH2 promoter induces expression. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (3 references)
PMID:33741715 SUPPORT In Vitro
"Ewing sarcomas are driven by EWS-ETS fusions, most commonly EWS-FLI1, which promotes widespread metabolic reprogramming, including activation of serine biosynthesis."
This supports EWS-FLI1 as a key driver fusion in Ewing sarcoma, but not all specific structural details in the descriptor.
PMID:17250957 SUPPORT Other
"It is associated in 85% of cases with the t(11;22)(q24:q12) chromosomal translocation that generates fusion of the 5' segment of the EWS gene with the 3' segment of the ETS family gene FLI-1."
Directly supports the 85% frequency of EWS-FLI1 translocation and its structural details.
PMID:17250957 SUPPORT Other
"The resulting EWS-FLI-1 fusion protein is believed to behave as an aberrant transcriptional activator that contributes to ESFT development by altering the expression of its target genes in a permissive cellular environment."
Supports the role of EWS-FLI1 as an aberrant transcription factor driving tumor development.
BAF Complex Retargeting
EWS-FLI1 uses the EWSR1 low-complexity/prion-like domain to retarget BRG1/BRM-associated factor (BAF/SWI-SNF) chromatin-remodeling complexes to tumor-specific enhancers. This neomorphic recruitment depends on tyrosine residues linked to phase-transition behavior of the EWSR1 domain and helps establish oncogenic enhancer activity.
Canonical EWS-FLI1 fusion enhanceropathy model
chromatin remodeling GO:0006338 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal chromatin remodeling (GO:0006338). GO:0006338 is a biological process from the Gene Ontology.
chromatin GO:0000785 Gene Ontology (GO) Relation: this pathophysiological event involves this cellular component This pathophysiological event involves chromatin (GO:0000785). GO:0000785 is a cellular component from the Gene Ontology.
Downstream
GGAA Microsatellite Enhancer Reprogramming BAF retargeting supports tumor-specific enhancer activation downstream of EWS-FLI1 occupancy. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (2 references)
PMID:28844694 SUPPORT In Vitro
"In Ewing sarcoma, we find that the BAF complex is recruited by the EWS-FLI1 fusion protein to tumor-specific enhancers and contributes to target gene activation."
Demonstrates that EWS-FLI1 recruits BAF complexes to tumor-specific enhancers and that this recruitment contributes to gene activation.
PMID:28844694 SUPPORT In Vitro
"This process is a neomorphic property of EWS-FLI1 compared to wild-type FLI1 and depends on tyrosine residues that are necessary for phase transitions of the EWSR1 prion-like domain."
Supports the phase-transition/prion-like-domain component of BAF retargeting by EWS-FLI1.
EWS-FLI1 Chromatin Hub Dynamics
Mechanism confidence: Provisional
EWS-FLI1 low-complexity-domain interactions support GGAA-associated transcription within a narrow interaction-strength optimum. A 2026 bioRxiv preprint reports endogenous dynamic sub-diffraction hubs that dissolve before macroscopic liquid-liquid phase separation. This is a provisional refinement of the published interaction-optimum model, not evidence that macroscopic condensates are required for oncogenesis.
Canonical EWS-FLI1 fusion enhanceropathy model
EWSR1 hgnc:3508 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves EWSR1 (hgnc:3508). hgnc:3508 is a gene from the HUGO Gene Nomenclature Committee. FLI1 hgnc:3749 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves FLI1 (hgnc:3749). hgnc:3749 is a gene from the HUGO Gene Nomenclature Committee. TRIM8 hgnc:15579 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves TRIM8 (hgnc:15579). hgnc:15579 is a gene from the HUGO Gene Nomenclature Committee.
regulation of gene expression GO:0010468 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal regulation of gene expression (GO:0010468). GO:0010468 is a biological process from the Gene Ontology. protein ubiquitination GO:0016567 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal protein ubiquitination (GO:0016567). GO:0016567 is a biological process from the Gene Ontology. protein stabilization GO:0050821 ↕ DYSREGULATED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves dysregulated protein stabilization (GO:0050821). GO:0050821 is a biological process from the Gene Ontology.
Downstream
GGAA Microsatellite Enhancer Reprogramming Dynamic EWS-FLI1 hubs concentrate the fusion on chromatin and tune enhancer activation at GGAA microsatellites. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (2 references)
PMID:41659683 SUPPORT In Vitro
"We found that endogenous EWS::FLI1 forms dynamic, sub-diffraction-limit hubs with mechanisms of dissolution that prevent the hubs from achieving macroscopic liquid-liquid phase separation."
Endogenous live-cell imaging in a bioRxiv preprint supports dynamic hubs; peer-reviewed replication is still needed.
PMID:35483357 SUPPORT In Vitro
"Quantitative single-cell and single-molecule imaging reveals that the oncogenic TF EWS::FLI1 requires a narrow optimum of LCD-LCD interactions to activate its target genes associated with GGAA microsatellites."
Supports a narrow low-complexity-domain interaction window for oncogenic transcription.
GGAA Microsatellite Enhancer Reprogramming
EWS-FLI1 binds GGAA microsatellite repeats and canonical ETS motifs, remodeling the enhancer landscape. At GGAA repeats, multimeric EWS-FLI1 opens chromatin and creates de novo enhancers that contact target promoters; at conserved ETS enhancers, EWS-FLI1 can displace wild-type ETS factors and repress tumor suppressor and lineage-regulatory programs.
Canonical EWS-FLI1 fusion enhanceropathy model
regulation of gene expression GO:0010468 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal regulation of gene expression (GO:0010468). GO:0010468 is a biological process from the Gene Ontology. chromatin remodeling GO:0006338 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal chromatin remodeling (GO:0006338). GO:0006338 is a biological process from the Gene Ontology.
chromatin GO:0000785 Gene Ontology (GO) Relation: this pathophysiological event involves this cellular component This pathophysiological event involves chromatin (GO:0000785). GO:0000785 is a cellular component from the Gene Ontology.
Downstream
Core Regulatory Circuitry Activation EWS-FLI1 establishes super-enhancers for KLF15, TCF4, and NKX2-2, building an autoregulatory transcription-factor circuit. Canonical EWS-FLI1 fusion enhanceropathy model
Blocked Differentiation Aberrant enhancer repression suppresses mesenchymal lineage regulators. Canonical EWS-FLI1 fusion enhanceropathy model
HOXD13-Driven Mesenchymal Plasticity A fusion-created GGAA enhancer activates the HOXD locus. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (6 references)
PMID:25453903 SUPPORT In Vitro
"We find that EWS-FLI1 reprograms gene regulatory circuits in Ewing sarcoma by directly inducing or repressing enhancers."
Directly supports enhancer-level reprogramming as a central EWS-FLI1 mechanism.
PMID:25453903 SUPPORT In Vitro
"At GGAA repeat elements, which lack evolutionary conservation and regulatory potential in other cell types, EWS-FLI1 multimers induce chromatin opening and create de novo enhancers that physically interact with target promoters."
Supports GGAA-repeat enhancer creation and chromatin opening.
PMID:22086061 SUPPORT In Vitro
"We found that in tumor cells, EWS-FLI targets regions of the genome distinct from FLI1, despite identical DNA-binding domains."
Supports Ian Davis lab evidence that the fusion retargets chromatin differently from wild-type FLI1.
+ 3 more references
ETV6 GGAA Counter-Regulation
Mechanism confidence: Provisional
ETV6 is a native ETS-family factor that competes with EWS-FLI1 at select short GGAA-repeat elements. This counter-regulatory layer restrains part of the enhanceropathy, and forced ETV6 degradation can paradoxically increase EWS-FLI1 transcriptional stress and tumor cell death.
Canonical EWS-FLI1 fusion enhanceropathy model
ETV6 hgnc:3495 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves ETV6 (hgnc:3495). hgnc:3495 is a gene from the HUGO Gene Nomenclature Committee.
regulation of gene expression GO:0010468 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal regulation of gene expression (GO:0010468). GO:0010468 is a biological process from the Gene Ontology.
Downstream
GGAA Microsatellite Enhancer Reprogramming ETV6 competition modulates EWS-FLI1 occupancy and output at short GGAA microsatellite enhancers. Canonical EWS-FLI1 fusion enhanceropathy model
Tumor Cell Proliferation and Survival ETV6 restrains excessive fusion activity and maintains a viable undifferentiated tumor state. ETV6 loss instead induces differentiation or cellular stress and suppresses growth in preclinical models. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (3 references)
PMID:36658219 SUPPORT In Vitro
"Using biochemical assays and epigenomics, we show that ETV6 competes with EWS-FLI1 for binding to select DNA elements enriched for short GGAA repeat sequences."
Supports ETV6 competition with EWS-FLI1 at short GGAA-repeat elements.
PMID:40215343 SUPPORT In Vitro
"Recent studies identified ETV6 as a vulnerability in Ewing sarcoma, where it competes with EWS::FLI1 at short GGAA repeats to restrain EWS::FLI1 function."
Supports ETV6 as a restraining factor and therapeutic vulnerability.
PMID:36658219 SUPPORT In Vitro
"Upon inactivating ETV6, EWS-FLI1 overtakes and hyper-activates these cis-elements to promote mesenchymal differentiation, with SOX11 being a key downstream target."
ETV6 loss releases fusion occupancy at selected sites and promotes differentiation rather than uniformly reversing all fusion activity.
GGAA Microsatellite Germline Susceptibility Architecture
Mechanism confidence: Provisional
Germline variation in GGAA microsatellite architecture can determine how strongly the acquired EWS-FLI1 fusion converts a locus into a neo-enhancer. At EGR2 and RREB1 susceptibility loci, longer or newly contiguous GGAA repeat alleles increase EWS-FLI1 binding and enhancer output, linking inherited repeat length to the somatic enhanceropathy and proliferative transcriptional programs.
Canonical EWS-FLI1 fusion enhanceropathy model Permissive developmental cell-of-origin model
EGR2 hgnc:3239 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves EGR2 (hgnc:3239). hgnc:3239 is a gene from the HUGO Gene Nomenclature Committee. RREB1 hgnc:10449 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves RREB1 (hgnc:10449). hgnc:10449 is a gene from the HUGO Gene Nomenclature Committee.
regulation of gene expression GO:0010468 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal regulation of gene expression (GO:0010468). GO:0010468 is a biological process from the Gene Ontology. chromatin remodeling GO:0006338 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal chromatin remodeling (GO:0006338). GO:0006338 is a biological process from the Gene Ontology. cell population proliferation GO:0008283 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased cell population proliferation (GO:0008283). GO:0008283 is a biological process from the Gene Ontology.
Downstream
GGAA Microsatellite Enhancer Reprogramming Germline GGAA repeat length and purity alter the strength of EWS-FLI1 neo-enhancer formation at susceptible loci. Canonical EWS-FLI1 fusion enhanceropathy model Permissive developmental cell-of-origin model
Tumor Cell Proliferation and Survival Susceptibility-locus enhancer activation can increase expression of proliferation-associated transcriptional regulators. Canonical EWS-FLI1 fusion enhanceropathy model Permissive developmental cell-of-origin model
Show evidence (4 references)
PMID:26214589 SUPPORT In Vitro
"At rs79965208, the A risk allele connected adjacent GGAA repeats by converting an interspaced GGAT motif into a GGAA motif, thereby increasing the number of consecutive GGAA motifs and thus the EWSR1-FLI1-dependent enhancer activity of this sequence, with epigenetic characteristics of an active..."
Supports the mechanism by which a germline risk allele creates a stronger GGAA enhancer at EGR2.
PMID:26214589 SUPPORT In Vitro
"EWSR1-FLI1 preferentially bound to the A risk allele, which increased global and allele-specific EGR2 expression."
Supports allele-specific EWS-FLI1 binding at a germline susceptibility repeat.
PMID:36787739 SUPPORT Human Clinical
"We identified 50 microsatellite alleles at 6p25.1 and observed that EwS-affected individuals had longer alleles (>135 bp) with more GGAA repeats."
Supports longer germline GGAA alleles in Ewing sarcoma cases at the RREB1-associated susceptibility locus.
+ 1 more reference
NuRD-LSD1 Transcriptional Repression
EWS-FLI1 recruits NuRD-associated HDAC and LSD1 activities to repress tumor-suppressive and lineage-regulatory genes. Repression contributes to transformation alongside enhancer activation. CHD4 also maintains global chromatin architecture and survival, but this distinct dependency should not be equated with regulation of EWS-FLI1 transcriptional output.
Canonical EWS-FLI1 fusion enhanceropathy model Transcription-coupled replication stress vulnerability model
CHD4 hgnc:1919 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves CHD4 (hgnc:1919). hgnc:1919 is a gene from the HUGO Gene Nomenclature Committee.
negative regulation of transcription by RNA polymerase II GO:0000122 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal negative regulation of transcription by RNA polymerase II (GO:0000122). GO:0000122 is a biological process from the Gene Ontology. chromatin organization GO:0006325 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal chromatin organization (GO:0006325). GO:0006325 is a biological process from the Gene Ontology. DNA repair GO:0006281 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal DNA repair (GO:0006281). GO:0006281 is a biological process from the Gene Ontology.
Downstream
Blocked Differentiation NuRD/LSD1/HDAC-mediated repression helps EWS-FLI1 maintain an immature, transformed state. Canonical EWS-FLI1 fusion enhanceropathy model
Tumor Cell Proliferation and Survival NuRD-associated repression of tumor-suppressive loci contributes to the transformed phenotype. This edge refers to transcriptional repression, not the separate CHD4 DNA-damage buffering mechanism. Canonical EWS-FLI1 fusion enhanceropathy model Transcription-coupled replication stress vulnerability model
Show evidence (2 references)
PMID:23178492 SUPPORT In Vitro
"Mechanistic studies demonstrate that the NuRD co-repressor complex interacts with EWS/FLI, and that its associated histone deacetylase and LSD1 activities contribute to the repressive function."
Biochemical and functional experiments establish the NuRD-associated repressive arm.
PMID:23178492 SUPPORT In Vitro
"Here, we demonstrate that a previously less-well characterized transcriptional repressive function of the EWS/FLI fusion is also required for the transformed phenotype of Ewing sarcoma."
Repression is functionally required in the tested Ewing cell models.
Core Regulatory Circuitry Activation
EWS-FLI1 activates super-enhancers controlling a core regulatory circuitry composed of transcription factors including KLF15, TCF4, and NKX2-2. These factors reinforce their own and each other's regulatory elements and cooperate with EWS-FLI1 to sustain proliferation, survival signaling, and the Ewing transcriptional state.
Canonical EWS-FLI1 fusion enhanceropathy model
KLF15 hgnc:14536 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves KLF15 (hgnc:14536). hgnc:14536 is a gene from the HUGO Gene Nomenclature Committee. TCF4 hgnc:11634 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves TCF4 (hgnc:11634). hgnc:11634 is a gene from the HUGO Gene Nomenclature Committee. NKX2-2 hgnc:7835 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves NKX2-2 (hgnc:7835). hgnc:7835 is a gene from the HUGO Gene Nomenclature Committee.
regulation of gene expression GO:0010468 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal regulation of gene expression (GO:0010468). GO:0010468 is a biological process from the Gene Ontology. cell population proliferation GO:0008283 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased cell population proliferation (GO:0008283). GO:0008283 is a biological process from the Gene Ontology.
Downstream
Tumor Cell Proliferation and Survival Core regulatory transcription factors sustain proliferation and oncogenic signaling pathways in Ewing sarcoma cells. Canonical EWS-FLI1 fusion enhanceropathy model
Blocked Differentiation Core regulatory circuitry reinforces the undifferentiated tumor state. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (2 references)
PMID:33080033 SUPPORT In Vitro
"Epigenomic analyses demonstrate that EWS-FLI1, the primary fusion driver for this cancer, directly establishes super-enhancers of each of these three TFs to activate their transcription."
Supports direct establishment of KLF15, TCF4, and NKX2-2 super-enhancers by EWS-FLI1.
PMID:33080033 SUPPORT In Vitro
"Functionally, CRC factors contribute significantly to cell proliferation of Ewing sarcoma both in vitro and in vivo."
Supports the downstream proliferation role of the core regulatory circuitry.
Blocked Differentiation
EWS-FLI1 and its downstream transcriptional circuitry repress mesenchymal lineage regulators, maintaining Ewing sarcoma cells in an immature, proliferative state. This mechanism is linked to the unresolved cell-of-origin question because only some early progenitor contexts tolerate EWS-FLI1 and progress toward an Ewing-like state.
cell differentiation GO:0030154 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cell differentiation (GO:0030154). GO:0030154 is a biological process from the Gene Ontology. mesenchymal cell differentiation GO:0048762 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased mesenchymal cell differentiation (GO:0048762). GO:0048762 is a biological process from the Gene Ontology.
Show evidence (2 references)
PMID:26000096 SUPPORT In Vitro
"Here we provide evidence that NKX2-2 mediates the EWS/FLI-controlled block of mesenchymal features."
Directly supports EWS/FLI-mediated repression of mesenchymal features and blocked differentiation programs.
PMID:25453903 SUPPORT In Vitro
"These divergent chromatin-remodeling patterns repress tumor suppressors and mesenchymal lineage regulators while activating oncogenes and potential therapeutic targets, such as the kinase VRK1."
Supports enhancer-level repression of mesenchymal lineage regulators.
ATF4-Serine-Glycine Metabolic Reprogramming
EWS-FLI1 and menin converge on ATF4 to activate a serine synthesis pathway transcriptional program. EWS-FLI1 also upregulates glutamine uptake and one-carbon cycle genes, linking fusion-driven transcription to biosynthetic metabolism, redox state, and survival.
Canonical EWS-FLI1 fusion enhanceropathy model
ATF4 hgnc:786 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves ATF4 (hgnc:786). hgnc:786 is a gene from the HUGO Gene Nomenclature Committee. PHGDH hgnc:8923 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves PHGDH (hgnc:8923). hgnc:8923 is a gene from the HUGO Gene Nomenclature Committee. SLC1A5 hgnc:10943 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SLC1A5 (hgnc:10943). hgnc:10943 is a gene from the HUGO Gene Nomenclature Committee.
L-serine biosynthetic process GO:0006564 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased L-serine biosynthetic process (GO:0006564). GO:0006564 is a biological process from the Gene Ontology. L-glutamine transport GO:0006868 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased L-glutamine transport (GO:0006868). GO:0006868 is a biological process from the Gene Ontology. generation of precursor metabolites and energy GO:0006091 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal generation of precursor metabolites and energy (GO:0006091). GO:0006091 is a biological process from the Gene Ontology.
Downstream
Tumor Cell Proliferation and Survival Fusion-driven metabolic rewiring supports biomass production, redox state, and survival in rapidly proliferating tumor cells. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (3 references)
PMID:33741715 SUPPORT In Vitro
"We identified and validated an EWS-FLI1 binding site at the ATF4 promoter, indicating that the fusion can directly activate ATF4 transcription."
Supports direct fusion-driven ATF4 activation.
PMID:29873416 SUPPORT In Vitro
"Here, we demonstrate that EWS-FLI1 positively regulates the expression of proteins required for serine-glycine biosynthesis and uptake of the alternative nutrient source glutamine."
Supports direct EWS-FLI1 control of serine-glycine biosynthesis and glutamine uptake.
PMID:29873416 SUPPORT In Vitro
"In summary, our study demonstrates that EWS-FLI1 reprograms the metabolism of EWS cells and that serine-glycine metabolism or glutamine uptake are potential targetable vulnerabilities in this tumor type."
Supports the therapeutic-vulnerability interpretation of this metabolic mechanism.
Transcription-Coupled R-loop Accumulation
EWS-FLI1-driven transcription and impaired regulation of damage-induced transcription promote RNA:DNA hybrids and replication stress in Ewing cell models. The stress state creates DNA-damage vulnerabilities and dependence on buffering pathways. It does not itself cause enhanced survival, and it is not synonymous with a uniform BRCA-mutant clinical phenotype.
Transcription-coupled replication stress vulnerability model
DNA replication GO:0006260 ↕ DYSREGULATED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves dysregulated DNA replication (GO:0006260). GO:0006260 is a biological process from the Gene Ontology.
Downstream
Context-Dependent BRCA1 Repair Impairment Transcription-associated BRCA1 retention can impair repair availability in the tested cellular context. Transcription-coupled replication stress vulnerability model
Show evidence (1 reference)
PMID:29513652 SUPPORT In Vitro
"Here we show that Ewing sarcoma cells display alterations in regulation of damage-induced transcription, accumulation of R-loops and increased replication stress."
Supports R-loop accumulation and replication stress downstream of EWS-FLI1 activity.
DHX9 Sequestration During Topoisomerase Stress
Mechanism confidence: Provisional
Following topoisomerase I poison exposure, EWS-FLI1 sequesters DHX9 helicase and prevents resolution of drug-induced R-loops. Excess DHX9 or reduced fusion expression confers SN-38 resistance independent of measured proliferation and global transcription rates. This supports a protein-interaction contribution under topoisomerase stress, without proving complete independence from transcription or untreated tumor initiation.
Transcription-coupled replication stress vulnerability model
DHX9 hgnc:2750 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves DHX9 (hgnc:2750). hgnc:2750 is a gene from the HUGO Gene Nomenclature Committee.
DNA replication GO:0006260 ↕ DYSREGULATED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves dysregulated DNA replication (GO:0006260). GO:0006260 is a biological process from the Gene Ontology.
Downstream
Transcription-Coupled R-loop Accumulation DHX9 sequestration prevents resolution of TOP1-poison-induced R-loops and increases replication stress. Transcription-coupled replication stress vulnerability model
Show evidence (1 reference)
PMID:40721661 SUPPORT In Vitro
"We discovered that EWS::FLI1 prevents the resolution of R-loops induced by these drugs via sequestering DHX9 helicase, ultimately resulting in R-loop accumulation, replication stress, and genome instability."
Supports the direct DHX9-sequestration arm of the R-loop mechanism.
STAG2-Modified Enhancer State
Mechanism confidence: Provisional
STAG2 loss remodels cohesin-dependent enhancer-promoter and CTCF contacts and perturbs PRC2-regulated programs in a subset of Ewing tumors. A recent study found loss of many short-GGAA binding sites with increased fusion occupancy and activity at multimeric repeats. Earlier work showed that STAG2 normally facilitates long-GGAA enhancer contacts; this is related evidence, not an independent replication of the same directional occupancy change. STAG2 protein loss and STAG2/TP53 co-mutation associate with adverse outcome in specific cohorts, but mutation, protein loss and inferred chromatin states are not interchangeable biomarkers. Paralog non-compensation is why losing STAG2 has an enhancer-specific consequence at all: cohesin-SA2 occupies a population of CTCF-free enhancers that cohesin-SA1 does not take over in its absence. The same paralog relationship makes STAG1 a selective dependency of STAG2-deficient cells. Both results come from general human cell and isogenic cancer-line systems rather than Ewing sarcoma models, so they supply the underlying cohesin biology and a candidate vulnerability, not an Ewing-specific or clinically tested one.
STAG2/cohesin-modified high-risk enhancer model
STAG2 hgnc:11355 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves STAG2 (hgnc:11355). hgnc:11355 is a gene from the HUGO Gene Nomenclature Committee.
chromatin remodeling GO:0006338 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal chromatin remodeling (GO:0006338). GO:0006338 is a biological process from the Gene Ontology. chromosome organization GO:0051276 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal chromosome organization (GO:0051276). GO:0051276 is a biological process from the Gene Ontology. regulation of gene expression GO:0010468 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal regulation of gene expression (GO:0010468). GO:0010468 is a biological process from the Gene Ontology. DNA replication GO:0006260 ↕ DYSREGULATED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves dysregulated DNA replication (GO:0006260). GO:0006260 is a biological process from the Gene Ontology. DNA repair GO:0006281 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal DNA repair (GO:0006281). GO:0006281 is a biological process from the Gene Ontology.
Downstream
GGAA Microsatellite Enhancer Reprogramming STAG2/cohesin status changes enhancer-promoter communication at long EWS-FLI1-bound GGAA repeats and rewires enhancer output. STAG2/cohesin-modified high-risk enhancer model
Metastatic Disease STAG2 loss can promote an aggressive, metastasis-prone transcriptional state. STAG2/cohesin-modified high-risk enhancer model
Show evidence (10 references)
PMID:34129824 SUPPORT In Vitro
"Strikingly, in STAG2 knockout cells the oncogenic genetic program driven by the fusion transcription factor EWS/FLI1 was highly perturbed, in part due to altered enhancer-promoter contacts. Moreover, loss of STAG2 also disrupted PRC2-mediated regulation of gene expression."
Supports STAG2 loss as a chromatin and transcriptional rewiring mechanism.
PMID:34129824 SUPPORT Model Organism
"Finally, consistent with clinical observations, functional studies revealed that loss of STAG2 enhances the metastatic potential of Ewing sarcoma xenografts."
Supports the metastasis-promoting consequence in xenograft models.
PMID:41950086 SUPPORT In Vitro
"Together, these findings reveal that STAG2 loss reprograms, rather than globally attenuates, EWS-FLI1 function, amplifying a high-risk oncogenic transcriptional state in Ewing sarcoma."
Supports the current model that STAG2 loss changes the quality of EWS-FLI1 enhancer activity.
+ 7 more references
Tumor Cell Proliferation and Survival
Multiple fusion-driven mechanisms converge on tumor cell proliferation and survival: core regulatory circuitry sustains oncogenic signaling, metabolic reprogramming supplies biomass and redox buffering, and replication-stress adaptation prevents apoptosis during genotoxic stress.
Canonical EWS-FLI1 fusion enhanceropathy model
cell population proliferation GO:0008283 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased cell population proliferation (GO:0008283). GO:0008283 is a biological process from the Gene Ontology.
Experimental models
Ewing sarcoma tumor organoid model systems ORGANOID Enables preclinical testing of tumor growth and survival responses.
Patient-derived Ewing sarcoma culture panel PRIMARY CELL CULTURE Assays patient-derived proliferation and therapy-response phenotypes.
Flow-perfusion Ewing sarcoma 3D scaffold coculture CO CULTURE Models stromal support of growth and drug-resistance phenotypes.
Downstream
Soft Tissue Mass / Localized Swelling Sustained proliferation and impaired differentiation produce the expanding local tumor mass. Canonical EWS-FLI1 fusion enhanceropathy model
Osseous Tumor Expansion and Bone Destruction Expansion of osseous tumors is associated with infiltrative bone destruction; the precise tumor-stromal mediators are not specified by the cited clinical imaging evidence.
Permissive Progenitor Cell State
Mechanism confidence: Provisional
The human cell of origin remains unresolved. Human neural crest-derived stem cells can tolerate EWS-FLI1, and early human embryonic mesenchymal cells can acquire an Ewing-like program and form xenografts. A zebrafish genetic model demonstrates neural crest-to-mesoderm reprogramming and tumors after lineage-targeted fusion expression. These experiments identify permissive states in distinct systems; neither molecular similarity nor engineered transformation uniquely traces the origin of human tumors.
Permissive developmental cell-of-origin model
early mesenchymal stem cell CL:0000134 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves early mesenchymal stem cell, annotated with mesenchymal stem cell (CL:0000134). CL:0000134 is a cell type from the Cell Ontology. migratory neural crest cell CL:0000333 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves migratory neural crest cell (CL:0000333). CL:0000333 is a cell type from the Cell Ontology.
cell differentiation GO:0030154 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal cell differentiation (GO:0030154). GO:0030154 is a biological process from the Gene Ontology.
Experimental models
Human embryonic mesenchymal stem cell EWS-FLI1 transformation model PRIMARY CELL CULTURE Demonstrates that only undifferentiated, early heMSCs (not adult MSCs or pediatric MSCs) fully support EWS-FLI1 transformation, linking progenitor developmental state to oncogenic permissiveness.
Animal models
Neural-crest-targeted EWSR1-FLI1 zebrafish Zebrafish Tests lineage-specific fusion tolerance and transformation.
EWS-FLI1-transduced human embryonic MSC xenograft Mouse Tests tumorigenicity of an experimentally permissive progenitor state.
Downstream
GGAA Microsatellite Enhancer Reprogramming Developmental chromatin context may determine which GGAA microsatellites become functional EWS-FLI1 enhancers. Permissive developmental cell-of-origin model
Show evidence (5 references)
PMID:21559395 SUPPORT In Vitro
"Although the histogenesis of ESFT is controversial, mesenchymal (MSC) and/or neural crest (NCSC) stem cells have been implicated as cells of origin."
Supports the leading mesenchymal and neural crest cell-of-origin hypotheses.
PMID:21559395 SUPPORT In Vitro
"Together these studies confirm that, unlike terminally differentiated cells but consistent with bone marrow-derived MSC, NCSC tolerate expression of EWS-FLI1 and ectopic expression of the oncogene initiates transition to an ESFT-like state."
Supports the ability of EWS-FLI1 to initiate an Ewing-like state in neural crest-related cells.
PMID:41136396 SUPPORT In Vitro
"Ewing sarcoma (ES) is an aggressive bone and soft tissue neoplasm characterized by EWSR::ETS rearrangements whose cellular origin remains unclear."
Establishes the unresolved nature of the cell-of-origin question.
+ 2 more references
IGF-1/YAP1 Developmental Cooperation
Mechanism confidence: Provisional
Transient IGF-1 exposure at concentrations chosen to mimic pubertal serum levels reprogrammed limb-derived mesenchymal cells from EWS-FLI1-mutant mice through a YAP1-centered mechanism and enabled stable tumorigenicity. This model suggests a developmental cooperating signal but does not establish puberty as the time of human initiation, a universal IGF-1 requirement, or a human cell of origin. YAP1/TAZ can oppose fusion transcription while promoting aggressive behavior in established tumors, so initiation and maintenance contexts require separate testing.
Permissive developmental cell-of-origin model
limb-derived mesenchymal progenitor cell CL:0000134 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves limb-derived mesenchymal progenitor cell, annotated with mesenchymal stem cell (CL:0000134). CL:0000134 is a cell type from the Cell Ontology.
IGF1 hgnc:5464 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves IGF1 (hgnc:5464). hgnc:5464 is a gene from the HUGO Gene Nomenclature Committee. YAP1 hgnc:16262 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves YAP1 (hgnc:16262). hgnc:16262 is a gene from the HUGO Gene Nomenclature Committee.
insulin-like growth factor receptor signaling pathway GO:0048009 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased insulin-like growth factor receptor signaling pathway (GO:0048009). GO:0048009 is a biological process from the Gene Ontology. intracellular signal transduction GO:0035556 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal intracellular signal transduction (GO:0035556). GO:0035556 is a biological process from the Gene Ontology. cell fate commitment GO:0045165 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal cell fate commitment (GO:0045165). GO:0045165 is a biological process from the Gene Ontology.
Downstream
Tumor Cell Proliferation and Survival IGF-1/YAP1 signaling can cooperate with EWS-FLI1 to promote stable transformation and tumorigenicity in a developmental mesenchymal context. Permissive developmental cell-of-origin model
Show evidence (2 references)
PMID:40080499 SUPPORT Model Organism
"We report that transient exposure to IGF-1 concentrations mimicking serum levels during puberty reprograms limb-derived mesenchymal cells of EWS::FLI1-mutant mice to stable transformation and tumorigenicity."
Supports pubertal-level IGF-1 exposure as a cooperating developmental signal.
PMID:40080499 SUPPORT Model Organism
"We identify a modular mechanism of IGF-1-driven tumor promotion in the early steps of EwS pathogenesis, in which Yap1 plays a central role."
Supports YAP1 as the central mediator of the IGF-1 cooperating mechanism.
EWS-FLI1 Dosage and State Plasticity
Fusion abundance and low-complexity-domain interaction strength are related but distinct control variables. TRIM8-mediated turnover prevents toxic fusion accumulation. Engineered graded depletion and restoration of endogenous EWS-FLI1 produce persistent transcriptional changes and increased metastatic behavior at intermediate depletion in preclinical models. This does not establish a clinical hazard of a particular inhibitor dose. Independently of those engineered perturbations, single-cell profiling of patient tumors associates an intermediate range of inferred fusion activity with proliferation and oxidative phosphorylation, and cells on either side of that range with a hypoxia program. That is a cross-sectional association in tumors, not a demonstration that fusion dose sets the program.
Canonical EWS-FLI1 fusion enhanceropathy model
TRIM8 hgnc:15579 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves TRIM8 (hgnc:15579). hgnc:15579 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Tumor Cell Proliferation and Survival A tolerated fusion-protein abundance supports survival; excessive expression after TRIM8 loss is deleterious. Canonical EWS-FLI1 fusion enhanceropathy model
Metastatic Disease Intermediate depletion and restoration enhanced extravasation and metastatic burden in preclinical models; the corresponding human causal contribution is unresolved. Canonical EWS-FLI1 fusion enhanceropathy model
Hybrid Mesenchymal Tumor States and Matrix Deposition Fusion dosage changes can contribute to mesenchymal plasticity, but dosage is not the sole determinant of the observed hybrid programs. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (4 references)
PMID:34329586 SUPPORT In Vitro
"Mechanistically, TRIM8 knockout led to an increase in EWS/FLI protein levels that was not tolerated."
CRISPR perturbation links TRIM8-mediated fusion turnover to a tolerated protein-abundance window.
PMID:41484205 SUPPORT In Vitro
"Strikingly, modest EF depletion promoted a pro-metastatic phenotype that diminished upon near-complete EF loss, revealing a paradoxical effect of submaximal EF inhibition."
Graded depletion in engineered preclinical models produces a non-monotonic phenotype; it does not demonstrate metastasis induced by partial drug inhibition in patients.
PMID:32049009 SUPPORT Human Clinical
"In EwS tumors, cell proliferation and strong oxidative phosphorylation metabolism are associated with a well-defined range of EWSR1-FLI1 activity."
Gives the dosage window a readout in patient tumors rather than only in engineered models: proliferation and oxidative phosphorylation track a bounded range of inferred fusion activity. Activity is inferred from a transcriptional signature, so this does not measure fusion protein abundance.
+ 1 more reference
CHD4 Chromatin Architecture Maintenance
Mechanism confidence: Provisional
CHD4/NuRD maintains global chromatin structure and limits spontaneous DNA damage in Ewing cells. Despite colocalization with EWS-FLI1 at enhancers, the reported survival effect did not operate by changing EWS-FLI1 activity or its oncogenic expression program. CHD4 loss causes apoptosis and increases sensitivity to DNA-damaging agents; combined CHD4 depletion and olaparib suppressed xenograft growth.
Canonical EWS-FLI1 fusion enhanceropathy model
CHD4 hgnc:1919 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves CHD4 (hgnc:1919). hgnc:1919 is a gene from the HUGO Gene Nomenclature Committee.
chromatin remodeling GO:0006338 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal chromatin remodeling (GO:0006338). GO:0006338 is a biological process from the Gene Ontology.
Downstream
Tumor Cell Proliferation and Survival Maintenance of chromatin architecture prevents spontaneous damage and apoptosis. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (2 references)
PMID:37963210 SUPPORT In Vitro
"Although CHD4 and NuRD colocalized with EWS-FLI1 at enhancers and super-enhancers, CHD4 promoted Ewing sarcoma cell survival not by modulating EWS-FLI1 activity and its oncogenic gene expression program but by regulating chromatin structure."
Separates CHD4 structural maintenance from EWS-FLI1 target-gene repression.
PMID:37963210 SUPPORT In Vitro
"CHD4 depletion led to a global increase in DNA accessibility and induction of spontaneous DNA damage, resulting in an increased susceptibility to DNA-damaging agents."
Links chromatin architecture maintenance to protection from spontaneous damage.
Context-Dependent BRCA1 Repair Impairment
Mechanism confidence: Provisional
Enrichment of BRCA1 at elongating transcription machinery can reduce its availability for damage repair in Ewing cell models. Other experiments found no apparent HR defect and attributed PARP sensitivity to trapped PARP-DNA complexes. These observations constrain the scope of an HR-deficiency model rather than establishing either uniform HR proficiency or uniform clinical BRCAness. PARP trapping and context-dependent HR impairment can coexist.
BRCA1 hgnc:1100 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves BRCA1 (hgnc:1100). hgnc:1100 is a gene from the HUGO Gene Nomenclature Committee.
double-strand break repair via homologous recombination GO:0000724 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased double-strand break repair via homologous recombination (GO:0000724). GO:0000724 is a biological process from the Gene Ontology.
Experimental models
Human embryonic mesenchymal stem cell EWS-FLI1 transformation model PRIMARY CELL CULTURE Measures altered BRCA1 expression, localization and damage-response phosphorylation alongside defective DNA repair in comet assays after EWS-FLI1 expression.
Show evidence (2 references)
PMID:29513652 SUPPORT In Vitro
"In addition, homologous recombination is impaired in Ewing sarcoma owing to an enriched interaction between BRCA1 and the elongating transcription machinery."
Supports BRCA1 sequestration and impaired HR in the studied Ewing models.
PMID:26505995 REFUTE In Vitro
"Here, we show that PARP inhibitor sensitivity in Ewing's sarcoma cells is not through an apparent defect in DNA repair by HR, but through hypersensitivity to trapped PARP1-DNA complexes."
A separate cellular study found HR proficiency and implicated PARP trapping; differences in assays and conditions remain relevant.
SLFN11-Dependent Replication Fork Arrest
EWS-FLI1 directly increases SLFN11 expression. SLFN11 blocks stressed replication forks and promotes susceptibility to DNA-damaging agents. Expression-outcome correlations are not a validated standalone clinical selection test. Loss of SLFN11 can confer treatment resistance and is associated with metabolic adaptation in Ewing models.
SLFN11 hgnc:26633 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SLFN11 (hgnc:26633). hgnc:26633 is a gene from the HUGO Gene Nomenclature Committee.
DNA replication GO:0006260 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased DNA replication (GO:0006260). GO:0006260 is a biological process from the Gene Ontology.
Show evidence (2 references)
PMID:25779942 SUPPORT In Vitro
"EWS-FLI1 binds near the transcription start site of SLFN11 promoter and acts as a positive regulator of SLFN11 expression in Ewing sarcoma cells."
Direct promoter binding and expression perturbation support fusion-driven SLFN11 transcription.
PMID:29395061 SUPPORT In Vitro
"Unlike ATR, SLFN11 neither interferes with the loading of CDC45 and PCNA nor inhibits the initiation of DNA replication but selectively blocks fork progression while inducing chromatin opening across replication initiation sites."
Mechanistic fork-blocking experiments in cancer cell models provide complementary, not exclusively Ewing-specific, support.
USP1-Survivin Stress Buffering
Mechanism confidence: Provisional
EWS-FLI1 increases USP1 expression. USP1 stabilizes survivin and buffers replication-stress-associated apoptosis, allowing continued Ewing cell survival. USP1 inhibition sensitizes cells to doxorubicin and etoposide in preclinical experiments; human efficacy has not been established.
Transcription-coupled replication stress vulnerability model
USP1 hgnc:12607 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves USP1 (hgnc:12607). hgnc:12607 is a gene from the HUGO Gene Nomenclature Committee. BIRC5 hgnc:593 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves BIRC5 (hgnc:593). hgnc:593 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Tumor Cell Proliferation and Survival USP1-dependent survivin stabilization suppresses stress-associated apoptosis. Transcription-coupled replication stress vulnerability model
Show evidence (1 reference)
PMID:37478161 SUPPORT In Vitro
"Together, our study demonstrates that USP1 is regulated by EWS::FLI1, the USP1-Survivin axis promotes EWS cell survival, and USP1 inhibition sensitizes cells to standard of care chemotherapy."
Ewing cellular experiments support a distinct fusion-regulated stress-buffering pathway.
Proposed POLQ Splicing and MMEJ Defect
Mechanism confidence: Provisional
A 2025 bioRxiv preprint reports that EWS-FLI1 expression or EWSR1 loss induces POLQ exon 25 skipping, reduces polymerase theta protein, and impairs microhomology-mediated end joining. Fusion knockdown and POLQ rescue support causality in tested models. Proposed synthetic lethality with other repair pathways requires independent replication and clinical evaluation; this is an emerging additional repair defect rather than a reason to erase the BRCA1 literature.
POLQ hgnc:9186 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves POLQ (hgnc:9186). hgnc:9186 is a gene from the HUGO Gene Nomenclature Committee.
alternative mRNA splicing, via spliceosome GO:0000380 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal alternative mRNA splicing, via spliceosome (GO:0000380). GO:0000380 is a biological process from the Gene Ontology.
Show evidence (1 reference)
PMID:40568108 SUPPORT In Vitro
"Expression of EWS-FLI1, or loss of EWSR1, causes exon 25 skipping of the POLQ transcript, decreased POLΘ expression, impaired MMEJ, and cellular sensitivity to inhibitors of the Fanconi Anemia (FA), NHEJ, or HR pathways, through the mechanism of synthetic lethality."
A 2025 bioRxiv preprint reports altered POLQ splicing and rescue experiments. This remains provisional and does not establish efficacy of the proposed inhibitors in patients.
SLFN11-Loss-Associated Lipid Remodeling
Mechanism confidence: Provisional
SLFN11-deficient Ewing models show reduced GPD2 expression and increased glycerophospholipid biosynthesis. Pharmacologic inhibition of glycerophospholipid synthesis increased SN-38 sensitivity in vitro, with modest and cell-line-dependent combination effects. The regulatory link from SLFN11 loss to GPD2 suppression and human predictive value remain unresolved. This loss state is not represented as a positive consequence of SLFN11 fork arrest.
Transcription-coupled replication stress vulnerability model
glycerophospholipid biosynthetic process GO:0046474 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased glycerophospholipid biosynthetic process (GO:0046474). GO:0046474 is a biological process from the Gene Ontology.
Downstream
Tumor Cell Proliferation and Survival Metabolic adaptation can support survival under genotoxic therapy in SLFN11-deficient cellular models. Transcription-coupled replication stress vulnerability model
Show evidence (1 reference)
PMID:41620417 SUPPORT In Vitro
"Here, we leverage transcriptomic and metabolomic profiling in patient-derived EWS models to demonstrate that SLFN11 loss drives downregulated mitochondrial glycerol-3-phosphate dehydrogenase (GPD2) expression, higher accumulation of glycerol-3-phosphate, fatty acid unsaturation, and enhanced..."
SLFN11 knockout and multi-omics support lipid remodeling in Ewing models. The molecular route to GPD2 suppression was not resolved.
PARP1-Supported Fusion Transcription
Mechanism confidence: Provisional
PARP1 interacts with EWS-FLI1 and EWS-ERG and supports fusion-mediated transcription; EWS-FLI1 also maintains PARP1 expression. This experimentally reported feedback connects transcription and damage response. The preclinical drug rationale has not translated into uniform clinical response.
Transcription-coupled replication stress vulnerability model
PARP1 hgnc:270 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves PARP1 (hgnc:270). hgnc:270 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
GGAA Microsatellite Enhancer Reprogramming PARP1 supports the broader fusion transcriptional program; a specific requirement at every GGAA enhancer has not been demonstrated. Transcription-coupled replication stress vulnerability model
Show evidence (1 reference)
PMID:22287547 SUPPORT In Vitro
"Notably, EWS-FLI1 fusion genes acted in a positive feedback loop to maintain the expression of PARP1, which was required for EWS-FLI-mediated transcription, thereby enforcing oncogene-dependent sensitivity to PARP-1 inhibition."
Ewing cellular studies support reciprocal dependence of fusion transcription and PARP1.
Tumor-Stroma IL-6/STAT3 Signaling
Mechanism confidence: Provisional
In flow-perfusion coculture, mesenchymal stromal cells and Ewing tumor cells respond to biophysical cues through IL-6/STAT3 signaling and altered drug response. This established-tumor microenvironment mechanism is distinct from IGF-1/YAP1 developmental initiation.
Canonical EWS-FLI1 fusion enhanceropathy model
mesenchymal stem cell CL:0000134 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves mesenchymal stem cell (CL:0000134). CL:0000134 is a cell type from the Cell Ontology.
interleukin-6-mediated signaling pathway GO:0070102 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased interleukin-6-mediated signaling pathway (GO:0070102). GO:0070102 is a biological process from the Gene Ontology.
Experimental models
Flow-perfusion Ewing sarcoma 3D scaffold coculture CO CULTURE Assays IL-6/STAT3 tumor-stroma signaling and drug response under biophysical stimulation; it does not test developmental IGF-1/YAP1 initiation.
Downstream
Tumor Cell Proliferation and Survival Stromal cytokine signaling modifies tumor-cell survival and drug response in a tissue-engineered model. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (1 reference)
PMID:27923328 SUPPORT In Vitro
"Here, we demonstrate that these same biophysical cues-modeled by coculturing ES cells and mesenchymal stem cells (MSCs) in 3D scaffolds within a flow perfusion bioreactor-activate interleukin-6 and transcription factor Stat3."
A tissue-engineered tumor-stroma coculture demonstrates IL-6/STAT3 activation under biophysical stimulation.
Hybrid Mesenchymal Tumor States and Matrix Deposition
Ewing tumors contain coexisting gene-regulatory programs. CD73-positive malignant subpopulations can retain fusion-activated genes while expressing normally repressed mesenchymal and extracellular-matrix genes. These CAF-like tumor cells deposit matrix near tumor borders and invasive foci. Their presence is not proof of a separate fibroblast lineage, and a universal binary fusion-high/fusion-low switch does not capture the observed heterogeneity.
extracellular matrix organization GO:0030198 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased extracellular matrix organization (GO:0030198). GO:0030198 is a biological process from the Gene Ontology.
Show evidence (3 references)
PMID:40667384 SUPPORT Human Clinical
"When we examined primary EwS patient tumors, we observed these same regulatory modules were variably enriched both across and within tumors, highlighting the existence of intratumoral heterogeneity in gene regulatory networks."
Single-cell RNA/ATAC analyses identify multiple coexisting regulatory programs rather than a single binary fusion-high/fusion-low axis.
PMID:37471463 SUPPORT In Vitro
"These cells retained expression of the fusion-activated gene signature alongside high expression of genes that are normally repressed by EWS::FLI1."
CD73-positive CAF-like tumor cells can occupy hybrid transcriptional states; they are malignant cells, not automatically nonmalignant fibroblasts.
PMID:37471463 SUPPORT In Vitro
"Thus, these EwS cells gained mesenchymal properties, including the capacity to deposit ECM, without losing proliferative or tumorigenic potential."
The source directly links the hybrid malignant-cell state to extracellular-matrix deposition. The annotation does not relabel these malignant cells as ordinary fibroblasts.
Osseous Tumor Expansion and Bone Destruction
In osseous Ewing sarcoma, infiltrative tumor growth destroys the affected bone and can extend through cortex into soft tissue. Local structural injury contributes to pain, swelling and fracture risk. These consequences are specific to osseous or bone-involving disease; treatment can also contribute to later fractures.
bone tissue UBERON:0002481 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in bone tissue (UBERON:0002481). UBERON:0002481 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Bone Pain Destructive local tumor growth can produce pain; the precise nociceptive pathway is not inferred from a specific molecular study.
Pathologic Fracture Bone involvement weakens the skeleton and predisposes to fracture. Disease-related and post-treatment fractures require separate interpretation.
Show evidence (1 reference)
PMID:25691401 SUPPORT Other
"In ES of the bone, plain radiographs exhibit permeative and infiltrative destruction of the affected bone"
Clinical imaging review supports a destructive osseous growth mechanism, distinct from extraskeletal disease.
EZH2-Associated Differentiation Repression
EWS-FLI1 induces EZH2, which contributes to repression of differentiation-associated genes and maintenance of an undifferentiated state. Genetic depletion impairs clonogenicity and tumorigenicity in preclinical systems. This dependency is distinct from the heterogeneous PRC2 changes following STAG2 loss and does not imply that every Ewing tumor will respond to an EZH2 inhibitor.
Canonical EWS-FLI1 fusion enhanceropathy model
EZH2 hgnc:3527 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves EZH2 (hgnc:3527). hgnc:3527 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Blocked Differentiation EZH2-associated repression maintains an undifferentiated state in Ewing experimental systems. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (2 references)
PMID:19289832 SUPPORT In Vitro
"Here, we found EWS/FLI1 bound to the EZH2 promoter in vivo, and induced EZH2 expression in ET and mesenchymal stem cells."
Chromatin binding and expression experiments support fusion-associated EZH2 induction; in vivo here describes binding within cells, not an animal efficacy result.
PMID:19289832 SUPPORT In Vitro
"Subsequent microarray analysis of EZH2 knock down, HDAC-inhibitor treatment and confirmation in independent assays revealed an undifferentiated phenotype maintained by EZH2 in ET."
Cellular perturbation supports maintenance of an undifferentiated transcriptional state.
HOXD13-Driven Mesenchymal Plasticity
Mechanism confidence: Provisional
Fusion-created enhancer activity at the HOXD locus induces a developmental transcriptional program. HOXD13 activates some genes normally repressed by EWS-FLI1 and shifts cells toward mesenchymal and migratory states. This provides a defined modifier of the differentiation block and contributes to a continuum of tumor states.
Canonical EWS-FLI1 fusion enhanceropathy model
HOXD13 hgnc:5136 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves HOXD13 (hgnc:5136). hgnc:5136 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Hybrid Mesenchymal Tumor States and Matrix Deposition HOXD13-mediated antagonism contributes to the mesenchymal transcriptional continuum. It is one candidate contributor to hybrid states, not a demonstrated sole cause of CD73 expression or matrix deposition. Canonical EWS-FLI1 fusion enhanceropathy model
Show evidence (2 references)
PMID:35653119 SUPPORT In Vitro
"We found that EWS::FLI1 creates a de novo GGAA microsatellite enhancer in a developmentally conserved regulatory region of the HOXD locus."
Enhancer perturbation supports fusion-dependent HOXD locus activation.
PMID:35653119 SUPPORT In Vitro
"More strikingly, HOXD13 bound and activated EWS::FLI1-repressed genes, leading to adoption of mesenchymal and migratory cell states that are normally suppressed by the fusion."
Supports transcriptional antagonism and a mesenchymal-state modifier rather than uniformly blocked differentiation.
BARD1-Loss and GBP1-Associated DNA-Damage Sensitivity
Mechanism confidence: Provisional
A BARD1-variant patient-derived Ewing cell line and BARD1-depletion experiments show enhanced sensitivity to PARP inhibition and radiation. BARD1 loss can increase GBP1 expression, which contributes to damage-induced apoptosis in the tested cells. Other signals also induce GBP1, so expression is not a specific BARD1-loss marker. This is a bounded experimental modifier of treatment response; neither disease-wide BARD1 prevalence, penetrant inherited Ewing susceptibility nor a validated clinical predictive biomarker is established.
BARD1 hgnc:952 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves BARD1 (hgnc:952). hgnc:952 is a gene from the HUGO Gene Nomenclature Committee. GBP1 hgnc:4182 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves GBP1 (hgnc:4182). hgnc:4182 is a gene from the HUGO Gene Nomenclature Committee.
Experimental models
BARD1-variant PSaRC318 and BARD1-depleted Ewing cells CELL LINE Tests BARD1 depletion and the contribution of GBP1 to PARP-inhibitor or radiation-associated apoptosis.
Show evidence (2 references)
PMID:36187937 SUPPORT In Vitro
"We demonstrate that PSaRC318 cells, a novel patient-derived cell line harboring a pathogenic BARD1 variant, are sensitive to PARP inhibition and by testing the effect of BARD1 depletion in additional Ewing sarcoma cell lines, we confirm that BARD1 loss enhances cell sensitivity to PARP..."
Patient-derived and BARD1-depleted cell models support an experimental modifier, not a validated patient biomarker or a ten-percent BARD1 frequency.
PMID:36187937 SUPPORT In Vitro
"Here, we demonstrate that GBP1 contributes to the enhanced sensitivity of BARD1 deficient Ewing cells to DNA damage."
GBP1 knockdown reduced radiation- and niraparib-associated apoptosis in PSaRC318 cells; GBP1 expression is not specific to BARD1 loss.
✶

Histopathology

4
Small Round Cell Tumor VERY_FREQUENT
Ewing sarcoma is a small round cell tumor of bone or soft tissue.
Show evidence (1 reference)
PMID:39158802 SUPPORT Other
"Histologically, most cases are made up of solid sheets of uniform small round cells with round nuclei containing finely stippled chromatin, inconspicuous nucleoli, and scant clear or eosinophilic cytoplasm, with ill-defined cell borders"
The guideline describes characteristic morphology without asserting a proven neuroectodermal human origin.
Homer Wright Rosette-like Formation OCCASIONAL
Atypical Ewing sarcoma of bone can show rosette-like textures resembling Homer-Wright rosettes, reflecting neuroectodermal differentiation features in a minority of cases rather than a required diagnostic feature.
Show evidence (1 reference)
PMID:3113717 SUPPORT Human Clinical
"Ewing's sarcoma (ES) of bone may occasionally display rosette-like textures mimicking Homer-Wright ones, as seen in neuroectodermic neoplasms (neuroblastoma, peripheral neuroepithelioma)."
Supports Homer Wright rosette-like formation as an occasional histopathologic pattern in atypical Ewing sarcoma of bone.
High Grade Tumor VERY_FREQUENT
Ewing sarcoma is managed as a high-grade sarcoma. Its small round cell morphology does not imply indolent disease; stage and treatment response provide additional risk information.
Show evidence (1 reference)
PMID:39158802 SUPPORT Other
"the NCCN, ESMO and British Sarcoma Group (BSG) guidelines follow-up recommendations for high-grade sarcomas, including ES, vary"
The guideline explicitly includes Ewing sarcoma among high-grade sarcomas.
Post-Chemotherapy Tumor Necrosis
Tumor cell necrosis can be assessed in Ewing sarcoma resection specimens, especially after neoadjuvant chemotherapy. The degree of tumor necrosis is a clinically meaningful histologic response marker: greater than or equal to 90% tumor necrosis defines a good chemotherapy response in many studies and is associated with improved local recurrence-free survival.
Show evidence (1 reference)
PMID:17177205 SUPPORT Human Clinical
"Patients with a good response to chemotherapy (> or = 90% tumor necrosis), had superior LRFS at 5 years (86% vs 51%, P = .015)."
Supports post-chemotherapy tumor necrosis as an Ewing sarcoma histologic-response measure with prognostic significance.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Ewing Sarcoma Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

7
Blood 1
Anemia HP:0001903 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Anemia (HP:0001903). HP:0001903 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:25691401 SUPPORT Other
"Anemia and leukocytosis are often observed in ES"
Clinical review supports the manifestation without a precise frequency.
Metabolism 1
Fever HP:0001945 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Fever (HP:0001945). HP:0001945 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:34485689 SUPPORT Other
"When present, constitutional symptoms include unintentional weight loss, fatigue, anemia, and fevers."
The didactic article general clinical discussion supports these nonspecific manifestations. This quote is not an observation in its fictional teaching case, and no symptom-specific frequency is inferred.
Musculoskeletal 1
Pathologic Fracture HP:0002756 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Pathologic fracture (HP:0002756). HP:0002756 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:11902298 SUPPORT Human Clinical
"Fracture occurred in 14 (15%) of 93 patients with long-bone ESFT, most commonly in the femur."
Retrospective long-bone cohort supports the complication, with restricted anatomy and historical treatment.
PMID:11902298 SUPPORT Human Clinical
"Nine (64%) of the 14 fractures occurred after the start of radiotherapy, and three of these were associated with either local recurrence or second malignancy."
Distinguishes disease-course fractures from presentation and treatment-associated fractures.
Constitutional 1
Bone Pain FREQUENT HP:0002653 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Bone pain (HP:0002653). HP:0002653 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:34235109 SUPPORT Human Clinical
"Pain (75.3%) was the most common symptom at presentation."
A 73-patient cohort restricted to adults reported pain in 75.3%; this supports the within-cohort frequency and common clinical presentation.
Growth 1
Weight Loss HP:0001824 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Weight loss (HP:0001824). HP:0001824 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:34485689 SUPPORT Other
"When present, constitutional symptoms include unintentional weight loss, fatigue, anemia, and fevers."
The didactic article general clinical discussion supports these nonspecific manifestations. This quote is not an observation in its fictional teaching case, and no symptom-specific frequency is inferred.
Neoplasm 2
Soft Tissue Mass / Localized Swelling Soft tissue neoplasm HP:0031459 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Soft tissue neoplasm (HP:0031459). HP:0031459 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:34235109 SUPPORT Human Clinical
"In this study, pain and swelling were the most common presenting complaints seen in 75.3% and 42.5% patients, respectively"
Adult single-center cohort supports swelling as a common presentation; no universal VERY_FREQUENT estimate is inferred.
Metastatic Disease OCCASIONAL Neoplasm HP:0002664 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Neoplasm (HP:0002664). HP:0002664 is a phenotype from the Human Phenotype Ontology.
HPO searches for metastasis and metastatic did not identify a disease-agnostic metastatic-neoplasm term; retrieved narrower terms describe other specific tumors or imaging findings. HP:0002664 is a broad neoplasm anchor, not an exact encoding of metastatic spread. The Ewing-specific meaning is retained in the phenotype name, description and metastatic-stage entry.
Show evidence (3 references)
PMID:34235109 SUPPORT Human Clinical
"Among 21 (28.8%) patients, the lung (61.9%) was the most common site of metastasis followed by the bone, bone marrow, and brain."
Supports the OCCASIONAL frequency band (5-29%) for metastatic disease at presentation — 28.8% of this 73-patient cohort presented with metastases — and the stated pattern of spread to lung, bone, and bone marrow. This is the frequency evidence; the survival items below support the separate prognostic claim, not the frequency.
PMID:36669140 SUPPORT Human Clinical
"The 3-year EFS estimates were 37.4% (95% CI, 29.3 to 45.5) for the standard arm and 39.1% (95% CI, 31.3 to 46.7) for the experimental arm (stratified EFS-event hazard ratio for experimental arm 1.00; 95% CI, 0.76 to 1.33; 1-sided, P = .50)."
Provides precise 3-year EFS data from the COG AEWS1221 phase III trial for metastatic Ewing sarcoma.
PMID:39158802 SUPPORT Other
"Although only 25% of patients have obvious metastases at diagnosis"
The contemporary guideline supports the approximate presentation frequency.
🧬

Genetic Associations

4
EWS-FLI1 Fusion (Somatic Fusion Oncogene)
Show evidence (1 reference)
PMID:17250957 SUPPORT Other
"It is associated in 85% of cases with the t(11;22)(q24:q12) chromosomal translocation that generates fusion of the 5' segment of the EWS gene with the 3' segment of the ETS family gene FLI-1."
Directly confirms the 85% frequency of the t(11;22) translocation creating EWS-FLI1.
STAG2 (Somatic Tumor Suppressor Mutation)
Gene: STAG2 hgnc:11355 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is STAG2 (hgnc:11355). hgnc:11355 is a gene from the HUGO Gene Nomenclature Committee. variant_origin: SOMATIC
Show evidence (3 references)
PMID:25223734 SUPPORT Human Clinical
"Apart from whole chromosome arm copy-number changes, the most common somatic mutations were detected in STAG2 (17%), CDKN2A (12%), TP53 (7%), EZH2, BCOR, and ZMYM3 (2.7% each)."
Establishes STAG2 as one of the most common recurrent somatic alterations in Ewing sarcoma.
PMID:36221002 SUPPORT Human Clinical
"Among patients with localised disease, 5-year event-free survival was 54% (95% CI 34-70%) and 75% (95% CI 63-84%) for patients with STAG2 loss vs. expression (P = 0.0034)."
Supports the adverse clinical association of STAG2 protein loss in localized Ewing sarcoma.
PMID:25186949 SUPPORT Human Clinical
"occurs by point mutation, rearrangement, and likely nongenetic mechanisms; and is associated with disease dissemination"
Establishes that STAG2 inactivation is not exclusively mutational, which is what reconciles the sequencing-based frequency recorded here with the higher immunohistochemical protein-loss rate recorded beside it.
TP53 (Somatic Tumor Suppressor Mutation)
Gene: TP53 hgnc:11998 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is TP53 (hgnc:11998). hgnc:11998 is a gene from the HUGO Gene Nomenclature Committee. variant_origin: SOMATIC
Show evidence (1 reference)
PMID:25223734 SUPPORT Human Clinical
"In an expanded cohort of 299 patients with clinical data, we discovered that STAG2 and TP53 mutations are often concurrent and are associated with poor outcome."
Supports TP53 mutation as part of the high-risk STAG2/TP53 co-altered Ewing sarcoma subset.
CDKN2A (Somatic Tumor Suppressor Deletion)
Gene: CDKN2A hgnc:1787 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is CDKN2A (hgnc:1787). hgnc:1787 is a gene from the HUGO Gene Nomenclature Committee. variant_origin: SOMATIC
Show evidence (1 reference)
PMID:25223734 SUPPORT Human Clinical
"Strikingly, STAG2 mutations and CDKN2A deletions were mutually exclusive, as confirmed in Ewing sarcoma cell lines."
Supports CDKN2A deletion as a recurrent secondary alteration distinct from STAG2-mutant Ewing sarcoma.
💊

Medical Actions

10
Neoadjuvant Chemotherapy
Action: Neoadjuvant ChemotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Neoadjuvant Chemotherapy (NCIT:C213450). NCIT:C213450 is a clinical intervention from the NCI Thesaurus. NCIT:C213450
Agent: vincristine CHEBI:28445 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses vincristine (CHEBI:28445). CHEBI:28445 is a therapeutic agent from Chemical Entities of Biological Interest. doxorubicin CHEBI:28748 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses doxorubicin (CHEBI:28748). CHEBI:28748 is a therapeutic agent from Chemical Entities of Biological Interest. cyclophosphamide CHEBI:4027 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses cyclophosphamide (CHEBI:4027). CHEBI:4027 is a therapeutic agent from Chemical Entities of Biological Interest. ifosfamide CHEBI:5864 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses ifosfamide (CHEBI:5864). CHEBI:5864 is a therapeutic agent from Chemical Entities of Biological Interest. etoposide CHEBI:4911 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses etoposide (CHEBI:4911). CHEBI:4911 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Interval-compressed vincristine, doxorubicin and cyclophosphamide alternating with ifosfamide and etoposide (VDC/IE), with growth-factor support and hematologic recovery criteria, is a standard systemic backbone. Randomized data support two-week over three-week scheduling in localized disease. Treatment is delivered before and after surgery and/or radiation.
Show evidence (2 references)
PMID:23091096 SUPPORT Human Clinical
"For localized Ewing sarcoma, chemotherapy administered every 2 weeks is more effective than chemotherapy administered every 3 weeks, with no increase in toxicity."
The randomized COG study supports interval compression; the conclusion applies to its localized-disease population.
PMID:36522207 SUPPORT Human Clinical
"Dose-intensive chemotherapy with vincristine, doxorubicin, cyclophosphamide, ifosfamide, and etoposide is more effective, less toxic, and shorter in duration"
EE2012 randomized evidence supports the VDC/IE approach over VIDE induction. The protocol also admitted Ewing-like sarcomas, a scope consideration when applying the result to modern molecular entities.
Surgical Resection
Action: Definitive Surgical ResectionNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Definitive Surgical Resection (NCIT:C154430). NCIT:C154430 is a clinical intervention from the NCI Thesaurus. NCIT:C154430
Platform: Surgery
Wide surgical resection with negative margins is preferred when feasible without excessive morbidity. Reconstruction may be needed for limb salvage.
Show evidence (1 reference)
PMID:39158802 SUPPORT Other
"surgery is the treatment of choice if tumor resection is possible with negative margins, without significant morbidity, and with a reasonable functional outcome."
Contemporary guideline supports margin-negative resection when feasible; this avoids causal superiority claims from a confounded observational treatment comparison.
Radiation Therapy
Action: Radiation TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Radiation Therapy (NCIT:C15313). NCIT:C15313 is a clinical intervention from the NCI Thesaurus. NCIT:C15313
Platform: Radiotherapy
Definitive radiation is used for unresectable tumors or when surgery would cause significant morbidity. Also used post-operatively for close or positive margins.
Show evidence (1 reference)
PMID:33818887 SUPPORT Other
"Standard treatment involves multiagent induction chemotherapy followed by local treatment with surgery, definitive radiation, or a combination of surgery and radiation followed by additional chemotherapy and consolidation local treatment to metastatic sites."
Confirms the role of definitive radiation as a local treatment option in Ewing sarcoma management.
Adjuvant Chemotherapy
Action: chemotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is chemotherapy (NCIT:C15632). NCIT:C15632 is a clinical intervention from the NCI Thesaurus. Ontology label: Chemotherapy NCIT:C15632
Platform: Small molecule
Systemic chemotherapy continues after local control to treat occult disseminated disease. Duration and consolidation depend on protocol and risk group; a fixed 9-12-month duration is not applicable to all modern interval-compressed regimens.
Show evidence (1 reference)
PMID:33818887 SUPPORT Other
"Standard treatment involves multiagent induction chemotherapy followed by local treatment with surgery, definitive radiation, or a combination of surgery and radiation followed by additional chemotherapy and consolidation local treatment to metastatic sites."
The review describes continuation of systemic chemotherapy after local treatment.
PARP Inhibitor Combination Therapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: talazoparib CHEBI:231344 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses talazoparib (CHEBI:231344). CHEBI:231344 is a therapeutic agent from Chemical Entities of Biological Interest. temozolomide CHEBI:72564 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses temozolomide (CHEBI:72564). CHEBI:72564 is a therapeutic agent from Chemical Entities of Biological Interest. olaparib CHEBI:83766 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses olaparib (CHEBI:83766). CHEBI:83766 is a therapeutic agent from Chemical Entities of Biological Interest. irinotecan CHEBI:80630 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses irinotecan (CHEBI:80630). CHEBI:80630 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
PARP-inhibitor combinations remain investigational in recurrent/refractory Ewing sarcoma. Talazoparib plus temozolomide produced no objective responses in ten phase-2 Ewing patients. A later pediatric olaparib-irinotecan phase-I/II study reported two Ewing responses, with a 6.3% response rate in its evaluable Ewing cohort. These limited signals do not establish routine efficacy or a validated HR-deficiency biomarker.
Mechanism Target:
INHIBITS PARP1-Supported Fusion Transcription — PARP inhibition interferes with PARP-dependent transcription and traps PARP-DNA complexes. Preclinical sensitivity is not equivalent to demonstrated patient benefit.
Show evidence (1 reference)
PMID:26505995 SUPPORT In Vitro
"Here, we show that PARP inhibitor sensitivity in Ewing's sarcoma cells is not through an apparent defect in DNA repair by HR, but through hypersensitivity to trapped PARP1-DNA complexes."
Supports PARP trapping as a cellular mechanism.
Show evidence (2 references)
PMID:31724813 SUPPORT Human Clinical
"In phase 2, 0 of 10 EWS subjects experienced an objective response; two experienced prolonged SD."
Clinical evidence supports feasibility but only partial therapeutic support because objective responses were not observed in the phase 2 Ewing cohort.
PMID:41591981 SUPPORT Human Clinical
"Two patients with Ewing sarcoma experienced a complete and a partial response for 10 and 42 cycles, respectively."
Limited activity in a later phase-I/II combination trial; this does not establish general efficacy or attribute the effect uniquely to PARP inhibition.
LSD1 Inhibitor Therapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: seclidemstat NCIT:C154328 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses seclidemstat (NCIT:C154328). NCIT:C154328 is a therapeutic agent from the NCI Thesaurus.
Platform: Small molecule
Seclidemstat (SP-2577) is an investigational LSD1-associated transcriptional modulator studied in fusion-positive sarcoma cells and trials. Laboratory activity links to fusion-dependent transcription, but clinical efficacy in Ewing sarcoma is unproven and preclinical xenograft activity has been limited.
Mechanism Target:
MODULATES NuRD-LSD1 Transcriptional Repression — Seclidemstat is intended to modulate LSD1-linked transcriptional and chromatin programs downstream of EWS-FLI1 and related FET fusion proteins.
Show evidence (1 reference)
PMID:40852926 SUPPORT In Vitro
"Seclidemstat recapitulated much of SP-2509 transcriptional activity in Ewing sarcoma."
Supports seclidemstat modulation of the Ewing sarcoma transcriptional program linked to the LSD1 pathograph arm.
Show evidence (2 references)
PMID:40852926 SUPPORT In Vitro
"Seclidemstat recapitulated much of SP-2509 transcriptional activity in Ewing sarcoma."
This is an in-vitro pharmacology result. A paper mentioning a trial does not verify its current registry status or clinical efficacy.
PMID:34453478 SUPPORT Model Organism
"SP-2577 (100 mg/kg/day × 28 days) statistically significantly (p < .05) inhibited growth of three of eight Ewing sarcoma (EwS), four of five rhabdomyosarcoma (RMS), and four of six osteosarcoma (OS) xenografts."
Supports in vivo preclinical activity in a subset of Ewing xenografts, but only partial support because the same abstract reports limited activity overall.
USP1 Inhibitor Therapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: USP1 inhibitor NCIT:C471 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses USP1 inhibitor, annotated with Enzyme Inhibitor (NCIT:C471). NCIT:C471 is a therapeutic agent from the NCI Thesaurus.
Platform: Small molecule
USP1 inhibition is a preclinical targeted strategy aimed at the EWS-FLI1 induced USP1-survivin survival buffer that helps Ewing sarcoma cells tolerate endogenous replication stress and standard chemotherapy exposure.
Mechanism Target:
INHIBITS USP1-Survivin Stress Buffering — USP1 inhibition blocks a survival adaptation within the replication-stress node by destabilizing the USP1-survivin axis and sensitizing cells to DNA damaging chemotherapy.
Show evidence (1 reference)
PMID:37478161 SUPPORT In Vitro
"Notably, USP1 inhibition sensitizes cells to doxorubicin and etoposide treatment."
Supports targeting the USP1-dependent replication-stress survival buffer in Ewing sarcoma cells.
Show evidence (1 reference)
PMID:37478161 SUPPORT In Vitro
"USP1 knockdown or inhibition arrests EWS cell growth and induces cell death by apoptosis."
Supports USP1 inhibition as a preclinical targeted treatment concept in Ewing sarcoma.
Dual PARP-HDAC Inhibition
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: kt-3283 NCIT:C62554 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses kt-3283, annotated with Poly (ADP-Ribose) Polymerase Inhibitor (NCIT:C62554). NCIT:C62554 is a therapeutic agent from the NCI Thesaurus.
Platform: Small molecule
The bifunctional compound kt-3283 has preclinical activity in Ewing cells and spheroids. It inhibits PARP1/2 and HDAC enzymes; these observations do not establish direct CHD4 inhibition or clinical efficacy.
Mechanism Target:
INHIBITS PARP1-Supported Fusion Transcription — The compound inhibits PARP1/2 as one of its two measured enzymatic targets.
Show evidence (1 reference)
PMID:37279093 SUPPORT In Vitro
"Here, we report the concept and characterization of a novel bifunctional PARPi (kt-3283) with dual activity toward PARP1/2 and HDAC enzymes in Ewing sarcoma cells."
Preclinical dual-target pharmacology, distinct from clinical talazoparib/temozolomide.
Show evidence (1 reference)
PMID:37279093 SUPPORT In Vitro
"Here, we report the concept and characterization of a novel bifunctional PARPi (kt-3283) with dual activity toward PARP1/2 and HDAC enzymes in Ewing sarcoma cells."
Preclinical dual-target pharmacology, distinct from clinical talazoparib/temozolomide.
Cabozantinib in Advanced Disease
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: cabozantinib CHEBI:72317 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses cabozantinib (CHEBI:72317). CHEBI:72317 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Cabozantinib, a MET/VEGFR2 inhibitor, showed activity in the single-arm CABONE phase-II trial in advanced Ewing sarcoma: 10/39 efficacy-evaluable patients had partial responses by six months. This is a salvage research option with toxicity and limited comparative evidence, not an established replacement for frontline multimodal therapy.
Show evidence (1 reference)
PMID:32078813 SUPPORT Human Clinical
"In patients with Ewing sarcoma, ten (26%; 95% CI 13-42) of 39 patients had an objective response (all partial responses) by 6 months"
Single-arm phase-II activity among efficacy-evaluable advanced Ewing patients, not proof of survival benefit or frontline efficacy.
High-Dose Ifosfamide for Recurrent or Refractory Disease
Action: chemotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is chemotherapy (NCIT:C15632). NCIT:C15632 is a clinical intervention from the NCI Thesaurus. Ontology label: Chemotherapy NCIT:C15632
Agent: ifosfamide CHEBI:5864 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses ifosfamide (CHEBI:5864). CHEBI:5864 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
The rEECur randomized salvage study provides comparative evidence favoring high-dose ifosfamide over topotecan-cyclophosphamide after earlier gemcitabine-docetaxel and irinotecan-temozolomide arms closed. The 2022 phase III conference report compared 73 patients per arm: median event-free survival was 5.7 versus 3.7 months and overall survival 16.8 versus 10.4 months for ifosfamide versus topotecan-cyclophosphamide. Renal toxicity and encephalopathy constrain selection and monitoring; this does not establish universal suitability or cure.
Show evidence (2 references)
DOI:10.1200/JCO.2022.40.17_suppl.LBA2 SUPPORT Human Clinical
"For the phase III comparison between TC and IFOS (both, 73 patients), median EFS was 3.7 months (95% CI, 2.1-6.2) for TC and 5.7 months (95% CI, 3.8-7.0) for IFOS. Median OS was 10.4 months (95% CI, 7.5-15.5) for TC and 16.8 months (95% CI, 11.1-25.8) for IFOS."
Primary randomized conference abstract reports event-free and overall survival in the contemporaneous phase III comparison; EFS must not be relabeled as PFS.
DOI:10.1200/JCO.2022.40.17_suppl.LBA2 SUPPORT Human Clinical
"The main grade 3/4 adverse events (% patients with an event) for TC (left-hand values) compared with IFOS were: febrile neutropenia (26% vs. 25%), infections (8% vs. 14%), vomiting (1% vs. 1%), nausea (0% vs. 3%), diarrhea (1% vs. 1%), encephalopathy (0% vs. 7%), and renal toxicity (0% vs. 8%)."
The comparative adverse-event data are relevant to salvage regimen selection.
🔬

Biochemical Markers

2
EWS-FLI1 Fusion Detection
Show evidence (2 references)
PMID:39158802 SUPPORT Other
"Genetic confirmation is required for ES diagnosis."
Defines the molecular-confirmation requirement.
PMID:39158802 SUPPORT Other
"All cases of ES harbor a FET-ETS fusion."
Includes rare FUS-containing fusions and distinguishes other round-cell sarcomas.
CD99 and NKX2.2 Immunoreactivity
Show evidence (2 references)
PMID:39158802 SUPPORT Other
"Immunohistochemically, neoplastic cells show a membranous pattern of intense and diffuse CD99 expression"
The guideline identifies typical CD99 staining.
PMID:39158802 SUPPORT Other
"However, it is important to note that CD99 and NKX2.2 are not entirely specific for ES"
Explicit specificity limitation.
🔬

Diagnosis

2
Integrated Histologic and Molecular Diagnosis
Core biopsy planned by the sarcoma team provides material for morphology, CD99/NKX2.2 immunohistochemistry and fusion characterization. Confirm a compatible FET-ETS fusion. Interpret EWSR1 break-apart FISH with care because EWSR1 rearrangements occur in other tumors; RNA fusion testing can resolve the partner or cryptic events. Exclude CIC-rearranged, BCOR-altered and EWSR1-non-ETS round-cell sarcomas.
integrated histologic and molecular diagnosis NCIT:C18020 NCI Thesaurus (NCIT)
Show evidence (2 references)
PMID:39158802 SUPPORT Other
"Definitive ES diagnosis should be performed (or reviewed) at a reference sarcoma center and based on sufficient biopsy material for conventional histology, immunohistochemistry, and molecular pathology"
Integrated diagnostic approach requiring adequate tissue and specialist interpretation.
PMID:39158802 SUPPORT Other
"All cases of ES harbor a FET-ETS fusion."
Includes rare FUS-containing fusions and distinguishes other round-cell sarcomas.
Local and Metastatic Staging
MRI defines the primary lesion and local extent. Chest imaging and whole-body assessment evaluate pulmonary and skeletal spread. Routine bilateral marrow biopsy is no longer standard when modern skeletal imaging shows no bone metastases; testing depends on the clinical context.
Diagnostic Imaging Testing NCIT:C16502 NCI Thesaurus (NCIT)
Show evidence (2 references)
PMID:39158802 SUPPORT Other
"Bilateral iliac bone marrow biopsy is no longer standard in staging, because of the extremely low rate of bone marrow involvement in the absence of bone metastasis detection by BS or PET"
Guideline limits routine marrow biopsy rather than excluding marrow disease.
PMID:25691401 SUPPORT Other
"Computed tomography (CT) is useful for depicting extraskeletal soft tissue masses, destruction of the bone cortex, and pulmonary metastasis"
Clinical imaging support for local and pulmonary staging.
🪜

Stages

3
Localized Disease
No detectable distant metastases on staging. Occult dissemination remains clinically important, so systemic chemotherapy is required in addition to local control.
Show evidence (1 reference)
PMID:39158802 SUPPORT Other
"in the past, 80–90% of patients with apparently localized disease died when treatment was reduced to a local approach."
Historical evidence summarized by the guideline explains systemic treatment despite localized staging.
Metastatic Disease at Diagnosis
Distant disease, commonly in lung, bone or bone marrow. Prognosis and local treatment decisions depend on extent and metastatic distribution; lung-only and multifocal extrapulmonary disease are not equivalent risk groups.
Show evidence (1 reference)
PMID:39158802 SUPPORT Other
"Disease dissemination is predominantly hematogenous, being lung, bones, and bone marrow as the most common metastatic sites."
Supports distribution of metastatic disease.
Relapsed or Refractory Disease
Recurrent disease after initial treatment or progression despite therapy. Salvage treatment and local control are individualized; clinical trials are important because durable outcomes remain poor.
Show evidence (1 reference)
PMID:32078813 SUPPORT Human Clinical
"The outcome is particularly poor, with a median overall survival of less than 12 months and a standard management remaining to be established"
The CABONE publication describes its advanced/recurrent treatment setting, not the prognosis of all newly diagnosed Ewing sarcoma.
📊

Related Datasets

6
Targeting the DNA Repair Pathway in Ewing Sarcoma ega:EGAS00001000839
Ewing’s Sarcoma is a bone and soft tissue tumor that primarily affects adolescents and young adults. With current therapies, 70% of patients with localized disease survive but survival for metastatic and recurrent disease is poor. Whole genome sequencing of 19 Ewing’s Sarcoma tumors showed that STAG2 was mutated in 10% (2/19) of the tumors and STAG2 protein was absent in 14% (13/106) tumors by immunohistochemical staining. Previous studies have shown that glioblastoma cells lacking STAG2 are more sensitive to poly-ADP ribose polymerase (PARP) inhibitors. We found that Ewing’s Sarcoma cell lines are sensitive to PARP inhibitors irrespective of STAG2 protein expression.
human
European Genome-phenome Archive study, matched because the disease is named in the study's own title ("Ewing Sarcoma"); description-level mentions were not accepted. EGA study_type: Other. Controlled access -- data require a Data Access Agreement. EGA metadata retrieved 2026-08-01.
Genomic landscape of Ewing sarcoma (ICGC project) ega:EGAS00001000855
The Ewing sarcoma project aims to sequence 100 complete genomes of cells of patients suffering from this disease. It is an initiative of great projection, since this is the second most common bone tumor in children and teenagers. The goal of the project is to establish the catalogue of somatic mutations that may cooperate with EWS-ETS fusion in the development of the tumor. The Ewing sarcoma project aims to perform 100 whole genome sequencing of germline and tumor DNA as well as at least 50 RNA-seq from tumors. Correlations between molecular profiles and clinical features will be established.
human
PMID:25223734
European Genome-phenome Archive study, matched because the disease is named in the study's own title ("Ewing Sarcoma"); description-level mentions were not accepted. EGA study_type: Other. Controlled access -- data require a Data Access Agreement. EGA metadata retrieved 2026-08-01.
Methylation of Ewing sarcoma tumors (ICGC) ega:EGAS00001002161
Ewing sarcoma (ES) is a primary bone tumor initiated by an EWSR1-ETS gene fusion. To characterize the methylation of Ewing sarcoma, reduced representation bisulfite sequencing was performed.
human
PMID:28134926
European Genome-phenome Archive study, matched because the disease is named in the study's own title ("Ewing Sarcoma"); description-level mentions were not accepted. EGA study_type: Other. Controlled access -- data require a Data Access Agreement. EGA metadata retrieved 2026-08-01.
Genomic Sequencing of Ewing Sarcoma dbgap:phs000804
Pediatric Ewing sarcoma is a pediatric cancer that primarily arises from the bone. It is characterized by chimeric fusions of the EWS gene and an ETS family transcription factor. In this study, we performed massively parallel sequencing of a larger collection of Ewing sarcoma tumors to define the genomic landscape of this disease. We found that these tumors are among of the most genetically normal cancers currently characterized. There was also a marked absence of recurrent mutations in immediately targetable signaling transduction pathway genes.
Located via OmicsDI, which aggregates across omics repositories; this record comes from dbgap. Only repositories with no other discovery route in this project and with a working accession resolver are curated from OmicsDI -- GEO, ArrayExpress, PRIDE, MetaboLights and EGA hits are excluded as duplicates of dedicated passes. Matched because the disease is named in the dataset's own title ("Ewing Sarcoma"). Retrieved 2026-08-02.
Genome-wide Association Study and Meta-Analysis of Ewing Sarcoma dbgap:phs001549
We combined a set of 122 French Ewing sarcoma (EWS) cases from the Institut Curie, 19 EWS cases from the National Cancer Institute (NCI) Center for Cancer Research (CCR), and 29 EWS cases from the NCI Bone Disease and Injury Study. All EWS cases were confirmed by medical record review and the presence of a specific EWSR1-ETS translocation were noted when data was available. Each participant provided informed consent and each participating study was approved by the Institutional Review Boards of their study center.
Located via OmicsDI, which aggregates across omics repositories; this record comes from dbgap. Only repositories with no other discovery route in this project and with a working accession resolver are curated from OmicsDI -- GEO, ArrayExpress, PRIDE, MetaboLights and EGA hits are excluded as duplicates of dedicated passes. Matched because the disease is named in the dataset's own title ("Ewing Sarcoma"). Retrieved 2026-08-02.
STAG2 Loss Rewires Oncogenic and Developmental Programs to Promote Metastasis in Ewing Sarcoma massive:MSV000082954
Adane B, Alexe G, Seong BKA, Lu D, Hwang E, Hnisz D, Lareau CA, Ross L, Lin S, Dela Cruz FS, Richardson M, Weintraub AS, Wang S, Balboni-Iniguez A, Dharia NV, Conway AS, Robichaud AL, Tanenbaum B, Krill-Burger JM, Vazquez F, Schenone M, Berman JN, Kung A, Carr SA, Aryee MJ, Young RA, Crompton BD, Stegmaier K. 2021 Cancer Cell. The core cohesin subunit STAG2 is recurrently mutated in Ewing sarcoma but its biological role is less clear. Herein, we demonstrate that cohesin complexes containing STAG2 occupy enhancer and polycomb repressive complex (PRC2) marked regulatory regions.
Located via OmicsDI, which aggregates across omics repositories; this record comes from massive. Only repositories with no other discovery route in this project and with a working accession resolver are curated from OmicsDI -- GEO, ArrayExpress, PRIDE, MetaboLights and EGA hits are excluded as duplicates of dedicated passes. Matched because the disease is named in the dataset's own title ("Ewing Sarcoma"). Retrieved 2026-08-02.
🔬

Clinical Trials

5
NCT00006734 PHASE_III COMPLETED
COG AEWS0031 randomized interval-compressed versus standard-interval VDC/IE in localized disease. Among 568 eligible patients, five-year EFS was 73% versus 65%, with similar toxicity. These are trial-population estimates, not an individual prognosis.
Show evidence (2 references)
PMID:23091096 SUPPORT Human Clinical
"EFS at a median of 5 years was 65% in the standard arm and 73% in the intensified arm (P=.048)."
Randomized efficacy result for interval compression.
url:https://clinicaltrials.gov/api/v2/studies/NCT00006734?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate SUPPORT Other
"{"protocolSection":{"identificationModule":{"nctId":"NCT00006734","briefTitle":"Comparison of Combination Chemotherapy Regimens in Treating Patients With Ewing's Sarcoma or Neuroectodermal..."
ClinicalTrials.gov structured registry fields retrieved on 2026-09-05 identify this trial and report COMPLETED. This is administrative status, separate from the published efficacy results; the record also gives its last update and completion date.
ISRCTN92192408 PHASE_III COMPLETED
EURO EWING 2012 compared VDC/IE-based and VIDE-based strategies. The VDC/IE strategy improved outcomes and reduced treatment burden. A separate second randomization in 272 eligible patients found no benefit from adding zoledronic acid to consolidation chemotherapy.
Show evidence (5 references)
PMID:36522207 SUPPORT Human Clinical
"Dose-intensive chemotherapy with vincristine, doxorubicin, cyclophosphamide, ifosfamide, and etoposide is more effective, less toxic, and shorter in duration"
EE2012 randomized evidence supports the VDC/IE approach over VIDE induction. The protocol also admitted Ewing-like sarcomas, a scope consideration when applying the result to modern molecular entities.
PMID:41832299 SUPPORT Human Clinical
"Adding zoledronic acid did not improve clinical outcomes in ES."
Published 2026 randomized result constrains translation of preclinical bone-targeting activity.
ICTRP:ISRCTN92192408 SUPPORT Other
"| Recruitment status | Completed | | Study type | Interventional | | Study design | Multi-centre international Phase III open-label randomized controlled trial (Treatment) |"
The WHO ICTRP record identifies EURO EWING 2012 as ISRCTN92192408, lists EudraCT2012-002107-17 as its secondary identifier, and reports completed status. These registry fields establish identity and administrative status, not treatment efficacy.
+ 2 more references
NCT02306161 PHASE_III ACTIVE_NOT_RECRUITING
COG AEWS1221 found that adding ganitumab to interval-compressed VDC/IE did not improve EFS in newly diagnosed metastatic Ewing sarcoma. The negative result does not disprove developmental IGF-1/YAP1 cooperation: established metastatic tumor treatment and tumor initiation test different hypotheses.
Show evidence (2 references)
PMID:36669140 SUPPORT Human Clinical
"The 3-year EFS estimates were 37.4% (95% CI, 29.3 to 45.5) for the standard arm and 39.1% (95% CI, 31.3 to 46.7) for the experimental arm"
AEWS1221 did not demonstrate improvement from adding the IGF1R antibody ganitumab to VDC/IE in newly diagnosed metastatic disease.
url:https://clinicaltrials.gov/api/v2/studies/NCT02306161?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate SUPPORT Other
"{"protocolSection":{"identificationModule":{"nctId":"NCT02306161","briefTitle":"Combination Chemotherapy With or Without Ganitumab in Treating Patients With Newly Diagnosed Metastatic Ewing..."
ClinicalTrials.gov structured registry fields retrieved on 2026-09-05 identify this trial and report ACTIVE_NOT_RECRUITING. This is administrative status, separate from the published efficacy results; the record also gives its last update and completion date.
NCT02116777 PHASE_II COMPLETED
ADVL1411 phase-I/II talazoparib-temozolomide trial. The phase-II Ewing cohort had no objective responses among ten patients; two had prolonged stable disease. This limits an unselected PARP-sensitivity treatment claim.
Show evidence (2 references)
PMID:31724813 SUPPORT Human Clinical
"In phase 2, 0 of 10 EWS subjects experienced an objective response; two experienced prolonged SD."
Clinical evidence supports feasibility but only partial therapeutic support because objective responses were not observed in the phase 2 Ewing cohort.
url:https://clinicaltrials.gov/api/v2/studies/NCT02116777?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate SUPPORT Other
"{"protocolSection":{"identificationModule":{"nctId":"NCT02116777","briefTitle":"Talazoparib and Temozolomide in Treating Younger Patients With Refractory or Recurrent..."
ClinicalTrials.gov structured registry fields retrieved on 2026-09-05 identify this trial and report COMPLETED. This is administrative status, separate from the published efficacy results; the record also gives its last update and completion date.
NCT02243605 PHASE_II ACTIVE_NOT_RECRUITING
CABONE evaluated cabozantinib in advanced Ewing sarcoma and osteosarcoma in separate cohorts. The Ewing efficacy analysis included 39 patients; response rates should not be pooled across the two diseases.
Show evidence (2 references)
PMID:32078813 SUPPORT Human Clinical
"In patients with Ewing sarcoma, ten (26%; 95% CI 13-42) of 39 patients had an objective response (all partial responses) by 6 months"
Single-arm phase-II activity among efficacy-evaluable advanced Ewing patients, not proof of survival benefit or frontline efficacy.
url:https://clinicaltrials.gov/api/v2/studies/NCT02243605?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate SUPPORT Other
"{"protocolSection":{"identificationModule":{"nctId":"NCT02243605","briefTitle":"Cabozantinib S-malate in Treating Patients With Relapsed Osteosarcoma or Ewing..."
ClinicalTrials.gov structured registry fields retrieved on 2026-09-05 identify this trial and report ACTIVE_NOT_RECRUITING. This is administrative status, separate from the published efficacy results; the record also gives its last update and completion date.
🧫

Experimental Models

5
Ewing sarcoma tumor organoid model systems ORGANOID namo:Organoid
Tumor organoids are part of the current Ewing sarcoma preclinical model landscape and provide a non-animal 3D system for therapy evaluation and mechanism-focused modeling alongside cell lines and xenografts.
Ewing sarcoma tumor organoid preclinical modeling
Organism
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Cell source
Ewing sarcoma tumor-derived cells
Culture
Three-dimensional tumor organoid culture
Publication
PMID:40911901
Pathograph links
EWS-FLI1 Fusion Oncogene Models fusion-positive tumor biology in a 3D non-animal context.
Tumor Cell Proliferation and Survival Enables preclinical testing of tumor growth and survival responses.
Show evidence (1 reference)
PMID:40911901 SUPPORT Other
"Through an international collaborative effort between the Children's Oncology Group Bone Tumor Committee and the Euro Ewing Consortium, we review the current landscape of preclinical modeling used in Ewing sarcoma research encompassing both in vitro (cell lines and tumor organoids) and in vivo..."
Supports tumor organoids as part of the Ewing sarcoma preclinical modeling landscape.
Patient-derived Ewing sarcoma culture panel PRIMARY_CELL_CULTURE namo:TwoDCellCulture
Patient-derived Ewing sarcoma cultures provide a primary-cell in vitro non-animal model for studying EWSR1 fusion status, proliferation, migration, and treatment response in models that differ transcriptionally from long-established cell lines.
Ewing sarcoma patient-derived ES cultures preclinical drug response testing
Organism
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Cell source
Patient-derived Ewing sarcoma tumor cultures
Culture
Patient-derived in vitro culture
Publication
PMID:41681984
Pathograph links
EWS-FLI1 Fusion Oncogene Models EWSR1 fusion-positive tumor state in patient-derived cultures.
Tumor Cell Proliferation and Survival Assays patient-derived proliferation and therapy-response phenotypes.
Findings
Patient-derived Ewing cultures retain EWSR1 fusion DNA.
Show evidence (1 reference)
PMID:41681984 SUPPORT In Vitro
"Results: All PDES contain EWSR1 fusion DNA, consistent with a diagnosis of ES."
Supports PDES as patient-derived, fusion-positive Ewing sarcoma models.
Show evidence (1 reference)
PMID:41681984 SUPPORT In Vitro
"To expedite this process, we have established and characterised patient-derived ES cultures (PDES) in vitro."
Supports this as a patient-derived in vitro Ewing sarcoma model system.
Flow-perfusion Ewing sarcoma 3D scaffold coculture CO_CULTURE
Flow-perfusion 3D scaffold cocultures combine Ewing sarcoma cells with mesenchymal stromal cells under biomechanical stimulation, enabling controlled testing of tumor-stroma signaling, IGF-1R/STAT3 biology, and drug-resistance mechanisms that are absent from standard monolayer systems.
Ewing sarcoma tumor-stroma coculture flow perfusion
mesenchymal stem cell CL:0000134 Cell Ontology (CL) Relation: this experimental model uses this cell type This experimental model uses mesenchymal stem cell (CL:0000134). CL:0000134 is a cell type from the Cell Ontology.
Organism
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Cell source
Ewing sarcoma cells cocultured with mesenchymal stem cells
Culture
3D scaffold coculture in a flow perfusion bioreactor
Publication
PMID:27923328
Pathograph links
Tumor-Stroma IL-6/STAT3 Signaling Assays IL-6/STAT3 tumor-stroma signaling and drug response under biophysical stimulation; it does not test developmental IGF-1/YAP1 initiation.
Tumor Cell Proliferation and Survival Models stromal support of growth and drug-resistance phenotypes.
Show evidence (2 references)
PMID:27923328 SUPPORT In Vitro
"Here, we demonstrate that these same biophysical cues-modeled by coculturing ES cells and mesenchymal stem cells (MSCs) in 3D scaffolds within a flow perfusion bioreactor-activate interleukin-6 and transcription factor Stat3."
Supports this as a 3D tumor-stroma coculture model for Ewing sarcoma.
PMID:26240353 SUPPORT In Vitro
"To address this issue, we cultured Ewing sarcoma (ES) cells on electrospun poly(ε-caprolactone) 3D scaffolds within a flow perfusion bioreactor."
Supports the flow-perfusion scaffold format for Ewing sarcoma drug-sensitivity modeling.
Human embryonic mesenchymal stem cell EWS-FLI1 transformation model PRIMARY_CELL_CULTURE namo:TwoDCellCulture
Early human embryonic mesenchymal stem cells transduced with EWS-FLI1 acquire an Ewing-like transcriptome. Tumor formation was tested separately in immunodeficient xenograft hosts. This engineered permissiveness differs from later MSC states tested in the study; it does not uniquely identify the human lineage of origin.
Ewing sarcoma EWS-FLI1 transformation embryonic developmental context
mesenchymal stem cell CL:0000134 Cell Ontology (CL) Relation: this experimental model uses this cell type This experimental model uses mesenchymal stem cell (CL:0000134). CL:0000134 is a cell type from the Cell Ontology.
Organism
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Cell source
Human embryonic mesenchymal stem cells (heMSCs) transduced with EWS::FLI1 lentivirus
Culture
Primary embryonic MSC culture with lentiviral oncogene transduction and xenograft validation
Publication
PMID:41136396
Pathograph links
EWS-FLI1 Fusion Oncogene Models EWS-FLI1 oncogene expression in an embryonic human mesenchymal developmental context, with xenograft tumor formation demonstrating transformation capacity.
Permissive Progenitor Cell State Demonstrates that only undifferentiated, early heMSCs (not adult MSCs or pediatric MSCs) fully support EWS-FLI1 transformation, linking progenitor developmental state to oncogenic permissiveness.
Context-Dependent BRCA1 Repair Impairment measures Measures altered BRCA1 expression, localization and damage-response phosphorylation alongside defective DNA repair in comet assays after EWS-FLI1 expression.
Limitations: The study does not directly measure R-loop accumulation or isolate homologous-recombination repair with an HR-specific functional assay; those mechanisms cannot be inferred solely from BRCA1 and total DNA-damage readouts.
Show evidence (1 reference)
PMID:41136396 SUPPORT In Vitro
"In summary, we show that EWS::FLI1 enforces an aberrant transcriptome and solely is able to endow transforming capacity when expressed in undifferentiated, early heMSCs."
The conclusion compares early embryonic MSCs with other tested MSC states. It does not exclude every other progenitor type or eliminate the animal component of tumorigenicity validation.
BARD1-variant PSaRC318 and BARD1-depleted Ewing cells CELL_LINE namo:TwoDCellCulture
PSaRC318 derives from one patient with a germline pathogenic BARD1 variant. BARD1 depletion in other Ewing lines and GBP1 knockdown test the cellular contribution to damage sensitivity. These interventions do not establish treatment benefit in patients.
Organism
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Cell source
Patient-derived PSaRC318 Ewing sarcoma cells and established Ewing cell lines
Culture
Cell culture with BARD1 or GBP1 siRNA, PARP inhibitors and radiation
Publication
PMID:36187937
Pathograph links
BARD1-Loss and GBP1-Associated DNA-Damage Sensitivity perturbs Tests BARD1 depletion and the contribution of GBP1 to PARP-inhibitor or radiation-associated apoptosis.
Limitations: Patient-derived and knockdown culture findings do not establish clinical predictive validity.
Show evidence (2 references)
PMID:36187937 SUPPORT In Vitro
"We demonstrate that PSaRC318 cells, a novel patient-derived cell line harboring a pathogenic BARD1 variant, are sensitive to PARP inhibition and by testing the effect of BARD1 depletion in additional Ewing sarcoma cell lines, we confirm that BARD1 loss enhances cell sensitivity to PARP..."
Patient-derived and BARD1-depleted cell models support an experimental modifier, not a validated patient biomarker or a ten-percent BARD1 frequency.
PMID:36187937 SUPPORT In Vitro
"Here, we demonstrate that GBP1 contributes to the enhanced sensitivity of BARD1 deficient Ewing cells to DNA damage."
GBP1 knockdown reduced radiation- and niraparib-associated apoptosis in PSaRC318 cells; GBP1 expression is not specific to BARD1 loss.
🐁

Animal Models

2
Neural-crest-targeted EWSR1-FLI1 zebrafish
Lineage-targeted fusion expression produced neural crest-to-mesoderm reprogramming and lethal Ewing-like tumors. This establishes origin and reprogramming within the zebrafish model, not definitive ancestry of human tumors.
Species
Zebrafish
Genotype
Neural-crest-targeted EWSR1::FLI1 expression
Publication
PMID:41072418
Pathograph links
Permissive Progenitor Cell State Tests lineage-specific fusion tolerance and transformation.
Show evidence (1 reference)
PMID:41072418 SUPPORT Model Organism
"Neural crest-derived cells uniquely tolerate expression of EWSR1::FLI1, and targeted expression of EWSR1::FLI1 in these cells generates lethal Ewing sarcomas."
Lineage-specific tolerance and tumor formation in zebrafish support a neural crest origin in this model, not definitive human ancestry.
EWS-FLI1-transduced human embryonic MSC xenograft
Tests tumorigenicity of engineered early human mesenchymal cells. The implanted cell origin is known, but this does not trace spontaneous human disease.
Species
Mouse
Genotype
Immunodeficient hosts xenografted with EWS::FLI1-transduced human embryonic MSCs
Publication
PMID:41136396
Pathograph links
Permissive Progenitor Cell State Tests tumorigenicity of an experimentally permissive progenitor state.
Show evidence (1 reference)
PMID:41136396 SUPPORT Model Organism
"Xenografting of EWS::FLI1-transduced heMSCs results in the formation of tumors expressing characteristic ES markers."
Animal-host tumorigenicity validation, separated from the in-vitro culture model.
{ }

Source YAML

click to show 
name: Ewing Sarcoma
creation_date: '2026-01-26T02:55:13Z'
description: >-
  Ewing sarcoma is an aggressive bone and soft tissue malignancy, most frequent in adolescents and
  young adults, defined by a FET-ETS fusion. Approximately 85% harbor EWSR1::FLI1; most remaining
  tumors carry EWSR1::ERG, with rare alternative ETS partners or FUS-containing fusions. EWSR1 rearrangement
  alone is not specific: diagnosis integrates morphology, immunophenotype and demonstration of a
  compatible fusion. CIC-rearranged, BCOR-altered and EWSR1-non-ETS round cell sarcomas are distinct
  entities. Most detailed mechanisms below were established in EWSR1::FLI1 models and should not
  automatically be generalized to every FET-ETS fusion. EWS-FLI1 rewires GGAA-repeat enhancers, recruits
  chromatin regulators, activates oncogenic transcription and metabolism, and represses differentiation.
  Chromatin architecture, fusion dosage, developmental context and secondary alterations modify these
  programs. R-loop stress and DNA-repair dependencies help explain experimental drug sensitivity,
  but do not establish universal clinical homologous-recombination deficiency or PARP-inhibitor benefit.
  The human cell of origin remains unresolved. Intensive systemic chemotherapy and appropriate local
  control remain the treatment backbone.
categories:
- Pediatric Cancer
- Bone Cancer
- Sarcoma
parents:
- bone sarcoma
has_subtypes:
- name: Osseous Ewing Sarcoma
  subtype_term:
    preferred_term: Ewing sarcoma of bone
    term:
      id: MONDO:0002625
      label: Ewing sarcoma of bone
  description: >-
    Primary tumors arising in bone, commonly the pelvis and long bones, with localized pain and swelling.
    Osseous presentation does not define a different fusion-driven molecular entity.
- name: Extraosseous Ewing Sarcoma
  subtype_term:
    preferred_term: extraskeletal Ewing sarcoma
    term:
      id: MONDO:0018270
      label: extraskeletal Ewing sarcoma
  description: >-
    Primary tumors arising in soft tissues outside bone, including chest-wall, paravertebral and
    extremity sites. These share the FET-ETS molecular definition and multimodal treatment principles
    of osseous Ewing sarcoma.
pathophysiology:
- name: EWS-FLI1 Fusion Oncogene
  genetic_context:
    variant_origin: SOMATIC
  description: >-
    The t(11;22)(q24;q12) translocation fuses the EWS gene (EWSR1) on chromosome 22 with the FLI1
    gene on chromosome 11. The resulting EWS-FLI1 protein functions as an aberrant FET-ETS transcription
    factor. It is the truncal driver of most Ewing sarcomas, but its oncogenic effect depends on
    a permissive developmental cell state and on downstream enhancer, transcriptional, metabolic,
    and DNA damage-response programs.
  genes:
  - preferred_term: EWSR1
    term:
      id: hgnc:3508
      label: EWSR1
  - preferred_term: FLI1
    term:
      id: hgnc:3749
      label: FLI1
  cell_types:
  - preferred_term: early mesenchymal stem cell
    term:
      id: CL:0000134
      label: mesenchymal stem cell
  - preferred_term: migratory neural crest cell
    term:
      id: CL:0000333
      label: migratory neural crest cell
  notes: >-
    Both candidate cells are bound here because the fusion is the transforming
    lesion but the lineage it arises in is unresolved; see the Permissive
    Progenitor Cell State node, which carries the evidence for each candidate.
    The pair is deliberate rather than a hedge to be tidied away: it makes the
    derived cell of origin read as two candidates, which is what this entry
    claims.
  biological_processes:
  - preferred_term: positive regulation of transcription by RNA polymerase II
    modifier: ABNORMAL
    term:
      id: GO:0045944
      label: positive regulation of transcription by RNA polymerase II
  downstream:
  - target: EWS-FLI1 Chromatin Hub Dynamics
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      Low-complexity-domain interactions enable chromatin-associated fusion hubs; endogenous dynamic
      hub measurements are currently supported by a preprint.
  - target: BAF Complex Retargeting
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      The EWSR1-derived low-complexity domain enables EWS-FLI1 to recruit BAF chromatin-remodeling
      complexes to tumor-specific enhancers.
  - target: GGAA Microsatellite Enhancer Reprogramming
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      EWS-FLI1 occupies GGAA microsatellite repeats and canonical ETS sites, creating de novo enhancers
      while repressing other enhancer classes.
  - target: NuRD-LSD1 Transcriptional Repression
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      EWS-FLI1 recruits NuRD-associated HDAC and LSD1 activities for transcriptional repression;
      the separate CHD4 survival dependency does not establish that CHD4 acts through EWS-FLI1 target-gene
      regulation.
  - target: ATF4-Serine-Glycine Metabolic Reprogramming
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    - replication_stress_vulnerability_model
    description: EWS-FLI1 directly activates ATF4 and metabolic stress-response programs.
  - target: Transcription-Coupled R-loop Accumulation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - high-output transcription
    - R-loop accumulation
    hypothesis_groups:
    - replication_stress_vulnerability_model
    description: >-
      High-output transcription and defective damage-associated transcriptional control promote R-loop
      accumulation and replication stress.
  - target: DHX9 Sequestration During Topoisomerase Stress
    causal_link_type: DIRECT
    hypothesis_groups:
    - replication_stress_vulnerability_model
    description: >-
      In TOP1-poison-treated Ewing cells, EWS-FLI1 binds DHX9 and interferes with resolution of drug-induced
      R-loops.
  - target: EWS-FLI1 Dosage and State Plasticity
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      The fusion protein is subject to dosage control and its abundance changes the transcriptional
      state.
    intermediate_mechanisms:
    - TRIM8-mediated ubiquitination and degradation
  - target: SLFN11-Dependent Replication Fork Arrest
    causal_link_type: DIRECT
    hypothesis_groups:
    - replication_stress_vulnerability_model
    description: >-
      EWS-FLI1 directly activates SLFN11 transcription.
    evidence:
    - reference: PMID:25779942
      reference_title: SLFN11 Is a Transcriptional Target of EWS-FLI1 and a Determinant of Drug Response in Ewing Sarcoma.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: EWS-FLI1 binds near the transcription start site of SLFN11 promoter and acts as a positive regulator of SLFN11 expression in Ewing sarcoma cells.
      explanation: >-
        Direct promoter binding and expression perturbation support fusion-driven SLFN11 transcription.
  - target: USP1-Survivin Stress Buffering
    causal_link_type: DIRECT
    hypothesis_groups:
    - replication_stress_vulnerability_model
    description: >-
      EWS-FLI1 increases USP1 expression and thereby supports survivin-dependent stress tolerance.
    evidence:
    - reference: PMID:37478161
      reference_title: "USP1 Expression Driven by EWS::FLI1 Transcription Factor Stabilizes Survivin and Mitigates Replication Stress in Ewing Sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Together, our study demonstrates that USP1 is regulated by EWS::FLI1, the USP1-Survivin axis promotes EWS cell survival, and USP1 inhibition sensitizes cells to standard of care chemotherapy.
      explanation: >-
        Ewing cellular experiments support a distinct fusion-regulated stress-buffering pathway.
  - target: Proposed POLQ Splicing and MMEJ Defect
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    hypothesis_groups:
    - replication_stress_vulnerability_model
    description: >-
      Fusion expression perturbs faithful POLQ splicing in the reported cellular models; this preprint-derived
      edge is provisional.
    evidence:
    - reference: PMID:40568108
      reference_title: Disruption of Microhomology-mediated End-joining in Ewing Sarcoma.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Expression of EWS-FLI1, or loss of EWSR1, causes exon 25 skipping of the POLQ transcript, decreased POLΘ expression, impaired MMEJ, and cellular sensitivity to inhibitors of the Fanconi Anemia (FA), NHEJ, or HR pathways, through the mechanism of synthetic lethality.
      explanation: >-
        A 2025 bioRxiv preprint reports altered POLQ splicing and rescue experiments. This remains
        provisional and does not establish efficacy of the proposed inhibitors in patients.
    intermediate_mechanisms:
    - POLQ exon 25 skipping and reduced polymerase theta expression
  - target: PARP1-Supported Fusion Transcription
    causal_link_type: DIRECT
    hypothesis_groups:
    - replication_stress_vulnerability_model
    description: >-
      Fusion expression maintains PARP1 expression in a reciprocal transcriptional dependency.
    evidence:
    - reference: PMID:22287547
      reference_title: "PARP-1 inhibition as a targeted strategy to treat Ewing's sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Notably, EWS-FLI1 fusion genes acted in a positive feedback loop to maintain the expression of PARP1, which was required for EWS-FLI-mediated transcription, thereby enforcing oncogene-dependent sensitivity to PARP-1 inhibition.
      explanation: >-
        Ewing cellular studies support reciprocal dependence of fusion transcription and PARP1.
  - target: EZH2-Associated Differentiation Repression
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      Fusion binding at the EZH2 promoter induces expression.
    evidence:
    - reference: PMID:19289832
      reference_title: EZH2 is a mediator of EWS/FLI1 driven tumor growth and metastasis blocking endothelial and neuro-ectodermal differentiation.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Here, we found EWS/FLI1 bound to the EZH2 promoter in vivo, and induced EZH2 expression in ET and mesenchymal stem cells.
      explanation: >-
        Chromatin binding and expression experiments support fusion-associated EZH2 induction; in
        vivo here describes binding within cells, not an animal efficacy result.
  evidence:
  - reference: PMID:33741715
    reference_title: "EWS-FLI1 and Menin Converge to Regulate ATF4 Activity in Ewing Sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Ewing sarcomas are driven by EWS-ETS fusions, most commonly EWS-FLI1, which promotes widespread metabolic reprogramming, including activation of serine biosynthesis."
    explanation: This supports EWS-FLI1 as a key driver fusion in Ewing sarcoma, but not all specific structural details in the descriptor.
  - reference: PMID:17250957
    reference_title: "The Biology of Ewing sarcoma."
    supports: SUPPORT
    snippet: "It is associated in 85% of cases with the t(11;22)(q24:q12) chromosomal translocation that generates fusion of the 5' segment of the EWS gene with the 3' segment of the ETS family gene FLI-1."
    explanation: Directly supports the 85% frequency of EWS-FLI1 translocation and its structural details.
    evidence_source: OTHER
  - reference: PMID:17250957
    reference_title: "The Biology of Ewing sarcoma."
    supports: SUPPORT
    snippet: "The resulting EWS-FLI-1 fusion protein is believed to behave as an aberrant transcriptional activator that contributes to ESFT development by altering the expression of its target genes in a permissive cellular environment."
    explanation: Supports the role of EWS-FLI1 as an aberrant transcription factor driving tumor development.
    evidence_source: OTHER
- name: BAF Complex Retargeting
  description: >-
    EWS-FLI1 uses the EWSR1 low-complexity/prion-like domain to retarget BRG1/BRM-associated factor
    (BAF/SWI-SNF) chromatin-remodeling complexes to tumor-specific enhancers. This neomorphic recruitment
    depends on tyrosine residues linked to phase-transition behavior of the EWSR1 domain and helps
    establish oncogenic enhancer activity.
  biological_processes:
  - preferred_term: chromatin remodeling
    modifier: ABNORMAL
    term:
      id: GO:0006338
      label: chromatin remodeling
  cellular_components:
  - preferred_term: chromatin
    term:
      id: GO:0000785
      label: chromatin
  downstream:
  - target: GGAA Microsatellite Enhancer Reprogramming
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      BAF retargeting supports tumor-specific enhancer activation downstream of EWS-FLI1 occupancy.
  evidence:
  - reference: PMID:28844694
    reference_title: "Cancer-Specific Retargeting of BAF Complexes by a Prion-like Domain."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "In Ewing sarcoma, we find that the BAF complex is recruited by the EWS-FLI1 fusion protein to tumor-specific enhancers and contributes to target gene activation."
    explanation: >-
      Demonstrates that EWS-FLI1 recruits BAF complexes to tumor-specific enhancers and that this
      recruitment contributes to gene activation.
  - reference: PMID:28844694
    reference_title: "Cancer-Specific Retargeting of BAF Complexes by a Prion-like Domain."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "This process is a neomorphic property of EWS-FLI1 compared to wild-type FLI1 and depends on tyrosine residues that are necessary for phase transitions of the EWSR1 prion-like domain."
    explanation: >-
      Supports the phase-transition/prion-like-domain component of BAF retargeting by EWS-FLI1.
- name: EWS-FLI1 Chromatin Hub Dynamics
  description: >-
    EWS-FLI1 low-complexity-domain interactions support GGAA-associated transcription within a narrow
    interaction-strength optimum. A 2026 bioRxiv preprint reports endogenous dynamic sub-diffraction
    hubs that dissolve before macroscopic liquid-liquid phase separation. This is a provisional refinement
    of the published interaction-optimum model, not evidence that macroscopic condensates are required
    for oncogenesis.
  mechanism_confidence: PROVISIONAL
  genes:
  - preferred_term: EWSR1
    term:
      id: hgnc:3508
      label: EWSR1
  - preferred_term: FLI1
    term:
      id: hgnc:3749
      label: FLI1
  - preferred_term: TRIM8
    term:
      id: hgnc:15579
      label: TRIM8
  biological_processes:
  - preferred_term: regulation of gene expression
    modifier: ABNORMAL
    term:
      id: GO:0010468
      label: regulation of gene expression
  - preferred_term: protein ubiquitination
    modifier: ABNORMAL
    term:
      id: GO:0016567
      label: protein ubiquitination
  - preferred_term: protein stabilization
    modifier: DYSREGULATED
    term:
      id: GO:0050821
      label: protein stabilization
  downstream:
  - target: GGAA Microsatellite Enhancer Reprogramming
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      Dynamic EWS-FLI1 hubs concentrate the fusion on chromatin and tune enhancer activation at GGAA
      microsatellites.
  evidence:
  - reference: PMID:41659683
    reference_title: "Dynamic regulation of endogenous transcription factor hubs at single-molecule resolution."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We found that endogenous EWS::FLI1 forms dynamic, sub-diffraction-limit hubs with mechanisms of dissolution that prevent the hubs from achieving macroscopic liquid-liquid phase separation."
    explanation: >-
      Endogenous live-cell imaging in a bioRxiv preprint supports dynamic hubs; peer-reviewed replication
      is still needed.
  - reference: PMID:35483357
    reference_title: "Tuning levels of low-complexity domain interactions to modulate endogenous oncogenic transcription."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Quantitative single-cell and single-molecule imaging reveals that the oncogenic TF EWS::FLI1 requires a narrow optimum of LCD-LCD interactions to activate its target genes associated with GGAA microsatellites."
    explanation: Supports a narrow low-complexity-domain interaction window for oncogenic transcription.
- name: GGAA Microsatellite Enhancer Reprogramming
  description: >-
    EWS-FLI1 binds GGAA microsatellite repeats and canonical ETS motifs, remodeling the enhancer
    landscape. At GGAA repeats, multimeric EWS-FLI1 opens chromatin and creates de novo enhancers
    that contact target promoters; at conserved ETS enhancers, EWS-FLI1 can displace wild-type ETS
    factors and repress tumor suppressor and lineage-regulatory programs.
  biological_processes:
  - preferred_term: regulation of gene expression
    modifier: ABNORMAL
    term:
      id: GO:0010468
      label: regulation of gene expression
  - preferred_term: chromatin remodeling
    modifier: ABNORMAL
    term:
      id: GO:0006338
      label: chromatin remodeling
  cellular_components:
  - preferred_term: chromatin
    term:
      id: GO:0000785
      label: chromatin
  downstream:
  - target: Core Regulatory Circuitry Activation
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      EWS-FLI1 establishes super-enhancers for KLF15, TCF4, and NKX2-2, building an autoregulatory
      transcription-factor circuit.
  - target: Blocked Differentiation
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: Aberrant enhancer repression suppresses mesenchymal lineage regulators.
  - target: HOXD13-Driven Mesenchymal Plasticity
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      A fusion-created GGAA enhancer activates the HOXD locus.
    evidence:
    - reference: PMID:35653119
      reference_title: "EWS::FLI1 and HOXD13 Control Tumor Cell Plasticity in Ewing Sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: We found that EWS::FLI1 creates a de novo GGAA microsatellite enhancer in a developmentally conserved regulatory region of the HOXD locus.
      explanation: >-
        Enhancer perturbation supports fusion-dependent HOXD locus activation.
  evidence:
  - reference: PMID:25453903
    reference_title: "EWS-FLI1 utilizes divergent chromatin remodeling mechanisms to directly activate or repress enhancer elements in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We find that EWS-FLI1 reprograms gene regulatory circuits in Ewing sarcoma by directly inducing or repressing enhancers."
    explanation: Directly supports enhancer-level reprogramming as a central EWS-FLI1 mechanism.
  - reference: PMID:25453903
    reference_title: "EWS-FLI1 utilizes divergent chromatin remodeling mechanisms to directly activate or repress enhancer elements in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "At GGAA repeat elements, which lack evolutionary conservation and regulatory potential in other cell types, EWS-FLI1 multimers induce chromatin opening and create de novo enhancers that physically interact with target promoters."
    explanation: Supports GGAA-repeat enhancer creation and chromatin opening.
  - reference: PMID:22086061
    reference_title: "Tumor-specific retargeting of an oncogenic transcription factor chimera results in dysregulation of chromatin and transcription."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We found that in tumor cells, EWS-FLI targets regions of the genome distinct from FLI1, despite identical DNA-binding domains."
    explanation: Supports Ian Davis lab evidence that the fusion retargets chromatin differently from wild-type FLI1.
  - reference: PMID:22086061
    reference_title: "Tumor-specific retargeting of an oncogenic transcription factor chimera results in dysregulation of chromatin and transcription."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Expression of EWS-FLI results in nucleosome depletion at targeted sites, whereas silencing of EWS-FLI in tumor cells restored nucleosome occupancy."
    explanation: Supports the chromatin-accessibility arm of the EWS-FLI1 enhanceropathy.
  - reference: PMID:41950086
    reference_title: "STAG2 loss amplifies EWS-FLI1-driven microsatellite enhancer activity promoting Ewing sarcoma aggressiveness."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "EWS-FLI1 engages GGAA microsatellite repeats to form de novo enhancers that activate oncogenic transcriptional programs essential for tumorigenesis."
    explanation: Confirms the GGAA microsatellite enhancer mechanism in a recent STAG2-focused study.
  - reference: PMID:28134926
    reference_title: "DNA methylation heterogeneity defines a disease spectrum in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We observed consistent DNA hypomethylation at enhancers regulated by the disease-defining EWS-FLI1 fusion protein, thus establishing epigenomic enhancer reprogramming as a ubiquitous and characteristic feature of Ewing sarcoma."
    explanation: Supports enhancer reprogramming as a recurrent epigenomic feature in patient tumors.
- name: ETV6 GGAA Counter-Regulation
  description: >-
    ETV6 is a native ETS-family factor that competes with EWS-FLI1 at select short GGAA-repeat elements.
    This counter-regulatory layer restrains part of the enhanceropathy, and forced ETV6 degradation
    can paradoxically increase EWS-FLI1 transcriptional stress and tumor cell death.
  mechanism_confidence: PROVISIONAL
  genes:
  - preferred_term: ETV6
    term:
      id: hgnc:3495
      label: ETV6
  biological_processes:
  - preferred_term: regulation of gene expression
    modifier: ABNORMAL
    term:
      id: GO:0010468
      label: regulation of gene expression
  downstream:
  - target: GGAA Microsatellite Enhancer Reprogramming
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      ETV6 competition modulates EWS-FLI1 occupancy and output at short GGAA microsatellite enhancers.
  - target: Tumor Cell Proliferation and Survival
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - EWS-FLI1 hyperactivation
    - cellular stress
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      ETV6 restrains excessive fusion activity and maintains a viable undifferentiated tumor state.
      ETV6 loss instead induces differentiation or cellular stress and suppresses growth in preclinical
      models.
  evidence:
  - reference: PMID:36658219
    reference_title: "ETV6 dependency in Ewing sarcoma by antagonism of EWS-FLI1-mediated enhancer activation."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Using biochemical assays and epigenomics, we show that ETV6 competes with EWS-FLI1 for binding to select DNA elements enriched for short GGAA repeat sequences."
    explanation: Supports ETV6 competition with EWS-FLI1 at short GGAA-repeat elements.
  - reference: PMID:40215343
    reference_title: "(GGAA)(3)-Based TF-PROTACs Enable Targeted Degradation of ETV6 to Inhibit Ewing Sarcoma Growth."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Recent studies identified ETV6 as a vulnerability in Ewing sarcoma, where it competes with EWS::FLI1 at short GGAA repeats to restrain EWS::FLI1 function."
    explanation: Supports ETV6 as a restraining factor and therapeutic vulnerability.
  - reference: PMID:36658219
    reference_title: ETV6 dependency in Ewing sarcoma by antagonism of EWS-FLI1-mediated enhancer activation.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Upon inactivating ETV6, EWS-FLI1 overtakes and hyper-activates these cis-elements to promote mesenchymal differentiation, with SOX11 being a key downstream target.
    explanation: >-
      ETV6 loss releases fusion occupancy at selected sites and promotes differentiation rather than
      uniformly reversing all fusion activity.
- name: GGAA Microsatellite Germline Susceptibility Architecture
  description: >-
    Germline variation in GGAA microsatellite architecture can determine how strongly the acquired
    EWS-FLI1 fusion converts a locus into a neo-enhancer. At EGR2 and RREB1 susceptibility loci,
    longer or newly contiguous GGAA repeat alleles increase EWS-FLI1 binding and enhancer output,
    linking inherited repeat length to the somatic enhanceropathy and proliferative transcriptional
    programs.
  mechanism_confidence: PROVISIONAL
  genes:
  - preferred_term: EGR2
    term:
      id: hgnc:3239
      label: EGR2
  - preferred_term: RREB1
    term:
      id: hgnc:10449
      label: RREB1
  biological_processes:
  - preferred_term: regulation of gene expression
    modifier: ABNORMAL
    term:
      id: GO:0010468
      label: regulation of gene expression
  - preferred_term: chromatin remodeling
    modifier: ABNORMAL
    term:
      id: GO:0006338
      label: chromatin remodeling
  - preferred_term: cell population proliferation
    modifier: INCREASED
    term:
      id: GO:0008283
      label: cell population proliferation
  downstream:
  - target: GGAA Microsatellite Enhancer Reprogramming
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    - cell_of_origin_context_model
    description: >-
      Germline GGAA repeat length and purity alter the strength of EWS-FLI1 neo-enhancer formation
      at susceptible loci.
  - target: Tumor Cell Proliferation and Survival
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - EGR2 enhancer activation
    - RREB1-mediated RAS/MAPK-associated transcription
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    - cell_of_origin_context_model
    description: >-
      Susceptibility-locus enhancer activation can increase expression of proliferation-associated
      transcriptional regulators.
  evidence:
  - reference: PMID:26214589
    reference_title: "Chimeric EWSR1-FLI1 regulates the Ewing sarcoma susceptibility gene EGR2 via a GGAA microsatellite."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "At rs79965208, the A risk allele connected adjacent GGAA repeats by converting an interspaced GGAT motif into a GGAA motif, thereby increasing the number of consecutive GGAA motifs and thus the EWSR1-FLI1-dependent enhancer activity of this sequence, with epigenetic characteristics of an active regulatory element."
    explanation: Supports the mechanism by which a germline risk allele creates a stronger GGAA enhancer at EGR2.
  - reference: PMID:26214589
    reference_title: "Chimeric EWSR1-FLI1 regulates the Ewing sarcoma susceptibility gene EGR2 via a GGAA microsatellite."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "EWSR1-FLI1 preferentially bound to the A risk allele, which increased global and allele-specific EGR2 expression."
    explanation: Supports allele-specific EWS-FLI1 binding at a germline susceptibility repeat.
  - reference: PMID:36787739
    reference_title: "Targeted long-read sequencing of the Ewing sarcoma 6p25.1 susceptibility locus identifies germline-somatic interactions with EWSR1-FLI1 binding."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified 50 microsatellite alleles at 6p25.1 and observed that EwS-affected individuals had longer alleles (>135 bp) with more GGAA repeats."
    explanation: Supports longer germline GGAA alleles in Ewing sarcoma cases at the RREB1-associated susceptibility locus.
  - reference: PMID:36787739
    reference_title: "Targeted long-read sequencing of the Ewing sarcoma 6p25.1 susceptibility locus identifies germline-somatic interactions with EWSR1-FLI1 binding."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "RREB1 knockdown reduced proliferation and clonogenic potential and reduced expression of cell cycle and DNA replication genes."
    explanation: Links the RREB1 susceptibility enhancer mechanism to proliferation and clonogenic growth.
- name: NuRD-LSD1 Transcriptional Repression
  description: >-
    EWS-FLI1 recruits NuRD-associated HDAC and LSD1 activities to repress tumor-suppressive and lineage-regulatory
    genes. Repression contributes to transformation alongside enhancer activation. CHD4 also maintains
    global chromatin architecture and survival, but this distinct dependency should not be equated
    with regulation of EWS-FLI1 transcriptional output.
  genes:
  - preferred_term: CHD4
    term:
      id: hgnc:1919
      label: CHD4
  biological_processes:
  - preferred_term: negative regulation of transcription by RNA polymerase II
    modifier: ABNORMAL
    term:
      id: GO:0000122
      label: negative regulation of transcription by RNA polymerase II
  - preferred_term: chromatin organization
    modifier: ABNORMAL
    term:
      id: GO:0006325
      label: chromatin organization
  - preferred_term: DNA repair
    modifier: ABNORMAL
    term:
      id: GO:0006281
      label: DNA repair
  downstream:
  - target: Blocked Differentiation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - repression of lineage-regulatory genes
    - repression of tumor-suppressive target genes
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      NuRD/LSD1/HDAC-mediated repression helps EWS-FLI1 maintain an immature, transformed state.
  - target: Tumor Cell Proliferation and Survival
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - CHD4-dependent chromatin architecture maintenance
    - suppression of spontaneous DNA damage
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    - replication_stress_vulnerability_model
    description: >-
      NuRD-associated repression of tumor-suppressive loci contributes to the transformed phenotype.
      This edge refers to transcriptional repression, not the separate CHD4 DNA-damage buffering
      mechanism.
  evidence:
  - reference: PMID:23178492
    reference_title: Mechanism and relevance of EWS/FLI-mediated transcriptional repression in Ewing sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Mechanistic studies demonstrate that the NuRD co-repressor complex interacts with EWS/FLI, and that its associated histone deacetylase and LSD1 activities contribute to the repressive function.
    explanation: >-
      Biochemical and functional experiments establish the NuRD-associated repressive arm.
  - reference: PMID:23178492
    reference_title: Mechanism and relevance of EWS/FLI-mediated transcriptional repression in Ewing sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Here, we demonstrate that a previously less-well characterized transcriptional repressive function of the EWS/FLI fusion is also required for the transformed phenotype of Ewing sarcoma.
    explanation: >-
      Repression is functionally required in the tested Ewing cell models.
- name: Core Regulatory Circuitry Activation
  description: >-
    EWS-FLI1 activates super-enhancers controlling a core regulatory circuitry composed of transcription
    factors including KLF15, TCF4, and NKX2-2. These factors reinforce their own and each other's
    regulatory elements and cooperate with EWS-FLI1 to sustain proliferation, survival signaling,
    and the Ewing transcriptional state.
  genes:
  - preferred_term: KLF15
    term:
      id: hgnc:14536
      label: KLF15
  - preferred_term: TCF4
    term:
      id: hgnc:11634
      label: TCF4
  - preferred_term: NKX2-2
    term:
      id: hgnc:7835
      label: NKX2-2
  biological_processes:
  - preferred_term: regulation of gene expression
    modifier: ABNORMAL
    term:
      id: GO:0010468
      label: regulation of gene expression
  - preferred_term: cell population proliferation
    modifier: INCREASED
    term:
      id: GO:0008283
      label: cell population proliferation
  downstream:
  - target: Tumor Cell Proliferation and Survival
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      Core regulatory transcription factors sustain proliferation and oncogenic signaling pathways
      in Ewing sarcoma cells.
  - target: Blocked Differentiation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - NKX2-2-mediated repression of mesenchymal features
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: Core regulatory circuitry reinforces the undifferentiated tumor state.
  evidence:
  - reference: PMID:33080033
    reference_title: "EWS-FLI1 regulates and cooperates with core regulatory circuitry in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Epigenomic analyses demonstrate that EWS-FLI1, the primary fusion driver for this cancer, directly establishes super-enhancers of each of these three TFs to activate their transcription."
    explanation: >-
      Supports direct establishment of KLF15, TCF4, and NKX2-2 super-enhancers by EWS-FLI1.
  - reference: PMID:33080033
    reference_title: "EWS-FLI1 regulates and cooperates with core regulatory circuitry in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Functionally, CRC factors contribute significantly to cell proliferation of Ewing sarcoma both in vitro and in vivo."
    explanation: Supports the downstream proliferation role of the core regulatory circuitry.
- name: Blocked Differentiation
  description: >-
    EWS-FLI1 and its downstream transcriptional circuitry repress mesenchymal lineage regulators,
    maintaining Ewing sarcoma cells in an immature, proliferative state. This mechanism is linked
    to the unresolved cell-of-origin question because only some early progenitor contexts tolerate
    EWS-FLI1 and progress toward an Ewing-like state.
  biological_processes:
  - preferred_term: cell differentiation
    modifier: DECREASED
    term:
      id: GO:0030154
      label: cell differentiation
  - preferred_term: mesenchymal cell differentiation
    modifier: DECREASED
    term:
      id: GO:0048762
      label: mesenchymal cell differentiation
  evidence:
  - reference: PMID:26000096
    reference_title: "EWS/FLI utilizes NKX2-2 to repress mesenchymal features of Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Here we provide evidence that NKX2-2 mediates the EWS/FLI-controlled block of mesenchymal features."
    explanation: Directly supports EWS/FLI-mediated repression of mesenchymal features and blocked differentiation programs.
  - reference: PMID:25453903
    reference_title: "EWS-FLI1 utilizes divergent chromatin remodeling mechanisms to directly activate or repress enhancer elements in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "These divergent chromatin-remodeling patterns repress tumor suppressors and mesenchymal lineage regulators while activating oncogenes and potential therapeutic targets, such as the kinase VRK1."
    explanation: Supports enhancer-level repression of mesenchymal lineage regulators.
- name: ATF4-Serine-Glycine Metabolic Reprogramming
  description: >-
    EWS-FLI1 and menin converge on ATF4 to activate a serine synthesis pathway transcriptional program.
    EWS-FLI1 also upregulates glutamine uptake and one-carbon cycle genes, linking fusion-driven
    transcription to biosynthetic metabolism, redox state, and survival.
  genes:
  - preferred_term: ATF4
    term:
      id: hgnc:786
      label: ATF4
  - preferred_term: PHGDH
    term:
      id: hgnc:8923
      label: PHGDH
  - preferred_term: SLC1A5
    term:
      id: hgnc:10943
      label: SLC1A5
  biological_processes:
  - preferred_term: L-serine biosynthetic process
    modifier: INCREASED
    term:
      id: GO:0006564
      label: L-serine biosynthetic process
  - preferred_term: L-glutamine transport
    modifier: INCREASED
    term:
      id: GO:0006868
      label: L-glutamine transport
  - preferred_term: generation of precursor metabolites and energy
    modifier: ABNORMAL
    term:
      id: GO:0006091
      label: generation of precursor metabolites and energy
  downstream:
  - target: Tumor Cell Proliferation and Survival
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - serine-glycine biosynthesis
    - glutamine uptake
    - one-carbon metabolism
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      Fusion-driven metabolic rewiring supports biomass production, redox state, and survival in
      rapidly proliferating tumor cells.
  evidence:
  - reference: PMID:33741715
    reference_title: "EWS-FLI1 and Menin Converge to Regulate ATF4 Activity in Ewing Sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We identified and validated an EWS-FLI1 binding site at the ATF4 promoter, indicating that the fusion can directly activate ATF4 transcription."
    explanation: Supports direct fusion-driven ATF4 activation.
  - reference: PMID:29873416
    reference_title: "EWS-FLI1 reprograms the metabolism of Ewing sarcoma cells via positive regulation of glutamine import and serine-glycine biosynthesis."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Here, we demonstrate that EWS-FLI1 positively regulates the expression of proteins required for serine-glycine biosynthesis and uptake of the alternative nutrient source glutamine."
    explanation: Supports direct EWS-FLI1 control of serine-glycine biosynthesis and glutamine uptake.
  - reference: PMID:29873416
    reference_title: "EWS-FLI1 reprograms the metabolism of Ewing sarcoma cells via positive regulation of glutamine import and serine-glycine biosynthesis."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "In summary, our study demonstrates that EWS-FLI1 reprograms the metabolism of EWS cells and that serine-glycine metabolism or glutamine uptake are potential targetable vulnerabilities in this tumor type."
    explanation: Supports the therapeutic-vulnerability interpretation of this metabolic mechanism.
- name: Transcription-Coupled R-loop Accumulation
  description: >-
    EWS-FLI1-driven transcription and impaired regulation of damage-induced transcription promote
    RNA:DNA hybrids and replication stress in Ewing cell models. The stress state creates DNA-damage
    vulnerabilities and dependence on buffering pathways. It does not itself cause enhanced survival,
    and it is not synonymous with a uniform BRCA-mutant clinical phenotype.
  biological_processes:
  - preferred_term: DNA replication
    modifier: DYSREGULATED
    term:
      id: GO:0006260
      label: DNA replication
  downstream:
  - target: Context-Dependent BRCA1 Repair Impairment
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    hypothesis_groups:
    - replication_stress_vulnerability_model
    description: >-
      Transcription-associated BRCA1 retention can impair repair availability in the tested cellular
      context.
    evidence:
    - reference: PMID:29513652
      reference_title: EWS-FLI1 increases transcription to cause R-loops and block BRCA1 repair in Ewing sarcoma.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: In addition, homologous recombination is impaired in Ewing sarcoma owing to an enriched interaction between BRCA1 and the elongating transcription machinery.
      explanation: >-
        Supports BRCA1 sequestration and impaired HR in the studied Ewing models.
    intermediate_mechanisms:
    - BRCA1 association with elongating transcription machinery
  evidence:
  - reference: PMID:29513652
    reference_title: "EWS-FLI1 increases transcription to cause R-loops and block BRCA1 repair in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Here we show that Ewing sarcoma cells display alterations in regulation of damage-induced transcription, accumulation of R-loops and increased replication stress."
    explanation: Supports R-loop accumulation and replication stress downstream of EWS-FLI1 activity.
- name: DHX9 Sequestration During Topoisomerase Stress
  description: >-
    Following topoisomerase I poison exposure, EWS-FLI1 sequesters DHX9 helicase and prevents resolution
    of drug-induced R-loops. Excess DHX9 or reduced fusion expression confers SN-38 resistance independent
    of measured proliferation and global transcription rates. This supports a protein-interaction
    contribution under topoisomerase stress, without proving complete independence from transcription
    or untreated tumor initiation.
  mechanism_confidence: PROVISIONAL
  genes:
  - preferred_term: DHX9
    term:
      id: hgnc:2750
      label: DHX9
  biological_processes:
  - preferred_term: DNA replication
    modifier: DYSREGULATED
    term:
      id: GO:0006260
      label: DNA replication
  downstream:
  - target: Transcription-Coupled R-loop Accumulation
    causal_link_type: DIRECT
    hypothesis_groups:
    - replication_stress_vulnerability_model
    description: >-
      DHX9 sequestration prevents resolution of TOP1-poison-induced R-loops and increases replication
      stress.
  evidence:
  - reference: PMID:40721661
    reference_title: "EWS::FLI1-DHX9 interaction promotes Ewing sarcoma sensitivity to DNA topoisomerase 1 poisons by altering R-loop metabolism."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We discovered that EWS::FLI1 prevents the resolution of R-loops induced by these drugs via sequestering DHX9 helicase, ultimately resulting in R-loop accumulation, replication stress, and genome instability."
    explanation: Supports the direct DHX9-sequestration arm of the R-loop mechanism.
- name: STAG2-Modified Enhancer State
  description: >-
    STAG2 loss remodels cohesin-dependent enhancer-promoter and CTCF contacts and perturbs PRC2-regulated
    programs in a subset of Ewing tumors. A recent study found loss of many short-GGAA binding sites
    with increased fusion occupancy and activity at multimeric repeats. Earlier work showed that
    STAG2 normally facilitates long-GGAA enhancer contacts; this is related evidence, not an independent
    replication of the same directional occupancy change. STAG2 protein loss and STAG2/TP53 co-mutation
    associate with adverse outcome in specific cohorts, but mutation, protein loss and inferred chromatin
    states are not interchangeable biomarkers. Paralog non-compensation is why losing STAG2 has an
    enhancer-specific consequence at all: cohesin-SA2 occupies a population of CTCF-free enhancers
    that cohesin-SA1 does not take over in its absence. The same paralog relationship makes STAG1
    a selective dependency of STAG2-deficient cells. Both results come from general human cell and
    isogenic cancer-line systems rather than Ewing sarcoma models, so they supply the underlying
    cohesin biology and a candidate vulnerability, not an Ewing-specific or clinically tested one.
  mechanism_confidence: PROVISIONAL
  genes:
  - preferred_term: STAG2
    term:
      id: hgnc:11355
      label: STAG2
  biological_processes:
  - preferred_term: chromatin remodeling
    modifier: ABNORMAL
    term:
      id: GO:0006338
      label: chromatin remodeling
  - preferred_term: chromosome organization
    modifier: ABNORMAL
    term:
      id: GO:0051276
      label: chromosome organization
  - preferred_term: regulation of gene expression
    modifier: ABNORMAL
    term:
      id: GO:0010468
      label: regulation of gene expression
  - preferred_term: DNA replication
    modifier: DYSREGULATED
    term:
      id: GO:0006260
      label: DNA replication
  - preferred_term: DNA repair
    modifier: ABNORMAL
    term:
      id: GO:0006281
      label: DNA repair
  downstream:
  - target: GGAA Microsatellite Enhancer Reprogramming
    causal_link_type: DIRECT
    hypothesis_groups:
    - cohesin_modified_high_risk_model
    description: >-
      STAG2/cohesin status changes enhancer-promoter communication at long EWS-FLI1-bound GGAA repeats
      and rewires enhancer output.
  - target: Metastatic Disease
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - altered enhancer-promoter contacts
    - PRC2 derepression
    - migratory and neurodevelopmental program rewiring
    hypothesis_groups:
    - cohesin_modified_high_risk_model
    description: STAG2 loss can promote an aggressive, metastasis-prone transcriptional state.
  evidence:
  - reference: PMID:34129824
    reference_title: "STAG2 loss rewires oncogenic and developmental programs to promote metastasis in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Strikingly, in STAG2 knockout cells the oncogenic genetic program driven by the fusion transcription factor EWS/FLI1 was highly perturbed, in part due to altered enhancer-promoter contacts. Moreover, loss of STAG2 also disrupted PRC2-mediated regulation of gene expression."
    explanation: Supports STAG2 loss as a chromatin and transcriptional rewiring mechanism.
  - reference: PMID:34129824
    reference_title: "STAG2 loss rewires oncogenic and developmental programs to promote metastasis in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Finally, consistent with clinical observations, functional studies revealed that loss of STAG2 enhances the metastatic potential of Ewing sarcoma xenografts."
    explanation: Supports the metastasis-promoting consequence in xenograft models.
  - reference: PMID:41950086
    reference_title: "STAG2 loss amplifies EWS-FLI1-driven microsatellite enhancer activity promoting Ewing sarcoma aggressiveness."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Together, these findings reveal that STAG2 loss reprograms, rather than globally attenuates, EWS-FLI1 function, amplifying a high-risk oncogenic transcriptional state in Ewing sarcoma."
    explanation: Supports the current model that STAG2 loss changes the quality of EWS-FLI1 enhancer activity.
  - reference: PMID:39487368
    reference_title: "STAG2 loss in Ewing sarcoma alters enhancer-promoter contacts dependent and independent of EWS::FLI1."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Subsequent genomic profiling and high-resolution chromatin interaction data from Capture Hi-C indicated that cohesin-STAG2 facilitates communication between EWS::FLI1-bound long GGAA repeats, presumably acting as neoenhancers, and their target promoters."
    explanation: Supports STAG2/cohesin control of long-GGAA neo-enhancer to promoter communication.
  - reference: PMID:39487368
    reference_title: "STAG2 loss in Ewing sarcoma alters enhancer-promoter contacts dependent and independent of EWS::FLI1."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Changes in CTCF-dependent chromatin contacts involving signature genes, unrelated to EWS::FLI1 binding, were also identified."
    explanation: Supports an EWS-FLI1-independent CTCF-contact arm of STAG2 loss.
  - reference: PMID:36221002
    reference_title: "Adverse prognostic impact of the loss of STAG2 protein expression in patients with newly diagnosed localised Ewing sarcoma: A report from the Children's Oncology Group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among patients with localised disease, 5-year event-free survival was 54% (95% CI 34-70%) and 75% (95% CI 63-84%) for patients with STAG2 loss vs. expression (P = 0.0034)."
    explanation: Supports adverse clinical prognosis associated with STAG2 protein loss in localized Ewing sarcoma.
  - reference: PMID:25223734
    reference_title: "Genomic landscape of Ewing sarcoma defines an aggressive subtype with co-association of STAG2 and TP53 mutations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In an expanded cohort of 299 patients with clinical data, we discovered that STAG2 and TP53 mutations are often concurrent and are associated with poor outcome."
    explanation: Supports the high-risk STAG2/TP53 co-alteration component of the model.
  - reference: PMID:29867216
    reference_title: "Distinct roles of cohesin-SA1 and cohesin-SA2 in 3D chromosome organization."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "cannot be replaced by the SA1-containing cohesin complex (cohesin-SA1) when SA2 is absent"
    explanation: >-
      Supplies the paralog non-compensation premise this node depends on: losing STAG2 is not
      buffered by cohesin-SA1 at the affected sites. Established in general human cells, not in
      Ewing sarcoma.
  - reference: PMID:29867216
    reference_title: "Distinct roles of cohesin-SA1 and cohesin-SA2 in 3D chromosome organization."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "cohesin-SA2 promotes cell-type-specific contacts between enhancers and promoters independently of CTCF"
    explanation: >-
      Identifies the CTCF-independent enhancer-promoter contact function of cohesin-SA2, which is
      the function the EWS-FLI1 neo-enhancer arm of this node assumes is lost. It does not itself
      show that loss at GGAA repeats.
  - reference: PMID:32467316
    reference_title: "STAG1 vulnerabilities for exploiting cohesin synthetic lethality in STAG2-deficient cancers."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "identified STAG1 as the most prominent and selective dependency of STAG2-deficient cells"
    explanation: >-
      Supports a STAG1-directed synthetic-lethal vulnerability created by the STAG2-altered state.
      Demonstrated by genome-wide screens in isogenic cancer cell lines generally, not in Ewing
      sarcoma models, and not tested clinically in this disease. This is distinct from the
      replication-fork route already cited from broader cancer models.
- name: Tumor Cell Proliferation and Survival
  description: >-
    Multiple fusion-driven mechanisms converge on tumor cell proliferation and survival: core regulatory
    circuitry sustains oncogenic signaling, metabolic reprogramming supplies biomass and redox buffering,
    and replication-stress adaptation prevents apoptosis during genotoxic stress.
  biological_processes:
  - preferred_term: cell population proliferation
    modifier: INCREASED
    term:
      id: GO:0008283
      label: cell population proliferation
  downstream:
  - target: Soft Tissue Mass / Localized Swelling
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - expansion of poorly differentiated malignant cells
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: Sustained proliferation and impaired differentiation produce the expanding local tumor mass.
  - target: Osseous Tumor Expansion and Bone Destruction
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Expansion of osseous tumors is associated with infiltrative bone destruction; the precise tumor-stromal
      mediators are not specified by the cited clinical imaging evidence.
    evidence:
    - reference: PMID:25691401
      reference_title: "Diagnosis and treatment of Ewing sarcoma of the bone: a review article."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: In ES of the bone, plain radiographs exhibit permeative and infiltrative destruction of the affected bone
      explanation: >-
        Clinical imaging review supports a destructive osseous growth mechanism, distinct from extraskeletal
        disease.
- name: Permissive Progenitor Cell State
  description: >-
    The human cell of origin remains unresolved. Human neural crest-derived stem cells can tolerate
    EWS-FLI1, and early human embryonic mesenchymal cells can acquire an Ewing-like program and form
    xenografts. A zebrafish genetic model demonstrates neural crest-to-mesoderm reprogramming and
    tumors after lineage-targeted fusion expression. These experiments identify permissive states
    in distinct systems; neither molecular similarity nor engineered transformation uniquely traces
    the origin of human tumors.
  mechanism_confidence: PROVISIONAL
  cell_types:
  - preferred_term: early mesenchymal stem cell
    term:
      id: CL:0000134
      label: mesenchymal stem cell
  - preferred_term: migratory neural crest cell
    term:
      id: CL:0000333
      label: migratory neural crest cell
  biological_processes:
  - preferred_term: cell differentiation
    modifier: ABNORMAL
    term:
      id: GO:0030154
      label: cell differentiation
  downstream:
  - target: GGAA Microsatellite Enhancer Reprogramming
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - cell_of_origin_context_model
    description: >-
      Developmental chromatin context may determine which GGAA microsatellites become functional
      EWS-FLI1 enhancers.
  evidence:
  - reference: PMID:21559395
    reference_title: "Modeling initiation of Ewing sarcoma in human neural crest cells."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Although the histogenesis of ESFT is controversial, mesenchymal (MSC) and/or neural crest (NCSC) stem cells have been implicated as cells of origin."
    explanation: Supports the leading mesenchymal and neural crest cell-of-origin hypotheses.
  - reference: PMID:21559395
    reference_title: "Modeling initiation of Ewing sarcoma in human neural crest cells."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Together these studies confirm that, unlike terminally differentiated cells but consistent with bone marrow-derived MSC, NCSC tolerate expression of EWS-FLI1 and ectopic expression of the oncogene initiates transition to an ESFT-like state."
    explanation: Supports the ability of EWS-FLI1 to initiate an Ewing-like state in neural crest-related cells.
  - reference: PMID:41136396
    reference_title: "EWS::FLI1 expression in human embryonic mesenchymal stem cells leads to transcriptional reprograming, defective DNA damage repair and Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Ewing sarcoma (ES) is an aggressive bone and soft tissue neoplasm characterized by EWSR::ETS rearrangements whose cellular origin remains unclear."
    explanation: Establishes the unresolved nature of the cell-of-origin question.
  - reference: PMID:41136396
    reference_title: "EWS::FLI1 expression in human embryonic mesenchymal stem cells leads to transcriptional reprograming, defective DNA damage repair and Ewing sarcoma."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Xenografting of EWS::FLI1-transduced heMSCs results in the formation of tumors expressing characteristic ES markers."
    explanation: Supports the embryonic mesenchymal stem-cell transformation model in xenografts.
  - reference: PMID:41072418
    reference_title: Origin of Ewing sarcoma by embryonic reprogramming of neural crest to mesoderm.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Neural crest-derived cells uniquely tolerate expression of EWSR1::FLI1, and targeted expression of EWSR1::FLI1 in these cells generates lethal Ewing sarcomas.
    explanation: >-
      Lineage-specific tolerance and tumor formation in zebrafish support a neural crest origin in
      this model, not definitive human ancestry.
- name: IGF-1/YAP1 Developmental Cooperation
  description: >-
    Transient IGF-1 exposure at concentrations chosen to mimic pubertal serum levels reprogrammed
    limb-derived mesenchymal cells from EWS-FLI1-mutant mice through a YAP1-centered mechanism and
    enabled stable tumorigenicity. This model suggests a developmental cooperating signal but does
    not establish puberty as the time of human initiation, a universal IGF-1 requirement, or a human
    cell of origin. YAP1/TAZ can oppose fusion transcription while promoting aggressive behavior
    in established tumors, so initiation and maintenance contexts require separate testing.
  mechanism_confidence: PROVISIONAL
  cell_types:
  - preferred_term: limb-derived mesenchymal progenitor cell
    term:
      id: CL:0000134
      label: mesenchymal stem cell
  genes:
  - preferred_term: IGF1
    term:
      id: hgnc:5464
      label: IGF1
  - preferred_term: YAP1
    term:
      id: hgnc:16262
      label: YAP1
  biological_processes:
  - preferred_term: insulin-like growth factor receptor signaling pathway
    modifier: INCREASED
    term:
      id: GO:0048009
      label: insulin-like growth factor receptor signaling pathway
  - preferred_term: intracellular signal transduction
    modifier: ABNORMAL
    term:
      id: GO:0035556
      label: intracellular signal transduction
  - preferred_term: cell fate commitment
    modifier: ABNORMAL
    term:
      id: GO:0045165
      label: cell fate commitment
  downstream:
  - target: Tumor Cell Proliferation and Survival
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - YAP1/TEAD transcriptional activity
    - stable transformation of EWS-FLI1-mutant mesenchymal cells
    hypothesis_groups:
    - cell_of_origin_context_model
    description: >-
      IGF-1/YAP1 signaling can cooperate with EWS-FLI1 to promote stable transformation and tumorigenicity
      in a developmental mesenchymal context.
  evidence:
  - reference: PMID:40080499
    reference_title: "YAP1 is a key regulator of EWS::FLI1-dependent malignant transformation upon IGF-1-mediated reprogramming of bone mesenchymal stem cells."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We report that transient exposure to IGF-1 concentrations mimicking serum levels during puberty reprograms limb-derived mesenchymal cells of EWS::FLI1-mutant mice to stable transformation and tumorigenicity."
    explanation: Supports pubertal-level IGF-1 exposure as a cooperating developmental signal.
  - reference: PMID:40080499
    reference_title: "YAP1 is a key regulator of EWS::FLI1-dependent malignant transformation upon IGF-1-mediated reprogramming of bone mesenchymal stem cells."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We identify a modular mechanism of IGF-1-driven tumor promotion in the early steps of EwS pathogenesis, in which Yap1 plays a central role."
    explanation: Supports YAP1 as the central mediator of the IGF-1 cooperating mechanism.
- name: EWS-FLI1 Dosage and State Plasticity
  description: >-
    Fusion abundance and low-complexity-domain interaction strength are related but distinct control
    variables. TRIM8-mediated turnover prevents toxic fusion accumulation. Engineered graded depletion
    and restoration of endogenous EWS-FLI1 produce persistent transcriptional changes and increased
    metastatic behavior at intermediate depletion in preclinical models. This does not establish
    a clinical hazard of a particular inhibitor dose. Independently of those engineered perturbations,
    single-cell profiling of patient tumors associates an intermediate range of inferred fusion
    activity with proliferation and oxidative phosphorylation, and cells on either side of that
    range with a hypoxia program. That is a cross-sectional association in tumors, not a
    demonstration that fusion dose sets the program.
  evidence:
  - reference: PMID:34329586
    reference_title: TRIM8 modulates the EWS/FLI oncoprotein to promote survival in Ewing sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Mechanistically, TRIM8 knockout led to an increase in EWS/FLI protein levels that was not tolerated.
    explanation: >-
      CRISPR perturbation links TRIM8-mediated fusion turnover to a tolerated protein-abundance window.
  - reference: PMID:41484205
    reference_title: "Modelling EWS::FLI1 protein fluctuations reveal determinants of tumor plasticity in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Strikingly, modest EF depletion promoted a pro-metastatic phenotype that diminished upon near-complete EF loss, revealing a paradoxical effect of submaximal EF inhibition.
    explanation: >-
      Graded depletion in engineered preclinical models produces a non-monotonic phenotype; it does
      not demonstrate metastasis induced by partial drug inhibition in patients.
  - reference: PMID:32049009
    reference_title: "Transcriptional Programs Define Intratumoral Heterogeneity of Ewing Sarcoma at Single-Cell Resolution."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In EwS tumors, cell proliferation and strong oxidative phosphorylation metabolism are associated with a well-defined range of EWSR1-FLI1 activity."
    explanation: >-
      Gives the dosage window a readout in patient tumors rather than only in engineered models:
      proliferation and oxidative phosphorylation track a bounded range of inferred fusion activity.
      Activity is inferred from a transcriptional signature, so this does not measure fusion protein
      abundance.
  - reference: PMID:32049009
    reference_title: "Transcriptional Programs Define Intratumoral Heterogeneity of Ewing Sarcoma at Single-Cell Resolution."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a subpopulation of cells from below and above the intermediary EWSR1-FLI1 activity is characterized by increased hypoxia"
    explanation: >-
      Supports the non-monotonic shape of the window independently of the depletion experiments:
      cells on both sides of the intermediate range adopt a hypoxia program rather than simply
      losing proliferative output.
  genes:
  - preferred_term: TRIM8
    term:
      id: hgnc:15579
      label: TRIM8
  downstream:
  - target: Tumor Cell Proliferation and Survival
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      A tolerated fusion-protein abundance supports survival; excessive expression after TRIM8 loss
      is deleterious.
    evidence:
    - reference: PMID:34329586
      reference_title: TRIM8 modulates the EWS/FLI oncoprotein to promote survival in Ewing sarcoma.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Mechanistically, TRIM8 knockout led to an increase in EWS/FLI protein levels that was not tolerated.
      explanation: >-
        CRISPR perturbation links TRIM8-mediated fusion turnover to a tolerated protein-abundance
        window.
  - target: Metastatic Disease
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      Intermediate depletion and restoration enhanced extravasation and metastatic burden in preclinical
      models; the corresponding human causal contribution is unresolved.
    evidence:
    - reference: PMID:41484205
      reference_title: "Modelling EWS::FLI1 protein fluctuations reveal determinants of tumor plasticity in Ewing sarcoma."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Transient EF depletion followed by rapid restoration, modelling oncoprotein fluctuations, caused persistent dysregulation of genes functionally linked to enhanced extravasation and metastatic burden in preclinical models.
      explanation: >-
        Supports a model-organism dissemination consequence of experimentally perturbed fusion dosage,
        not a human treatment outcome.
  - target: Hybrid Mesenchymal Tumor States and Matrix Deposition
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      Fusion dosage changes can contribute to mesenchymal plasticity, but dosage is not the sole
      determinant of the observed hybrid programs.
    evidence:
    - reference: PMID:41484205
      reference_title: "Modelling EWS::FLI1 protein fluctuations reveal determinants of tumor plasticity in Ewing sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Strikingly, modest EF depletion promoted a pro-metastatic phenotype that diminished upon near-complete EF loss, revealing a paradoxical effect of submaximal EF inhibition.
      explanation: >-
        Graded depletion in engineered preclinical models produces a non-monotonic phenotype; it
        does not demonstrate metastasis induced by partial drug inhibition in patients.
- name: CHD4 Chromatin Architecture Maintenance
  mechanism_confidence: PROVISIONAL
  description: >-
    CHD4/NuRD maintains global chromatin structure and limits spontaneous DNA damage in Ewing cells.
    Despite colocalization with EWS-FLI1 at enhancers, the reported survival effect did not operate
    by changing EWS-FLI1 activity or its oncogenic expression program. CHD4 loss causes apoptosis
    and increases sensitivity to DNA-damaging agents; combined CHD4 depletion and olaparib suppressed
    xenograft growth.
  evidence:
  - reference: PMID:37963210
    reference_title: The Chromatin Remodeler CHD4 Sustains Ewing Sarcoma Cell Survival by Controlling Global Chromatin Architecture.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Although CHD4 and NuRD colocalized with EWS-FLI1 at enhancers and super-enhancers, CHD4 promoted Ewing sarcoma cell survival not by modulating EWS-FLI1 activity and its oncogenic gene expression program but by regulating chromatin structure.
    explanation: >-
      Separates CHD4 structural maintenance from EWS-FLI1 target-gene repression.
  - reference: PMID:37963210
    reference_title: The Chromatin Remodeler CHD4 Sustains Ewing Sarcoma Cell Survival by Controlling Global Chromatin Architecture.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: CHD4 depletion led to a global increase in DNA accessibility and induction of spontaneous DNA damage, resulting in an increased susceptibility to DNA-damaging agents.
    explanation: >-
      Links chromatin architecture maintenance to protection from spontaneous damage.
  genes:
  - preferred_term: CHD4
    term:
      id: hgnc:1919
      label: CHD4
  biological_processes:
  - preferred_term: chromatin remodeling
    modifier: ABNORMAL
    term:
      id: GO:0006338
      label: chromatin remodeling
  downstream:
  - target: Tumor Cell Proliferation and Survival
    causal_link_type: DIRECT
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      Maintenance of chromatin architecture prevents spontaneous damage and apoptosis.
    evidence:
    - reference: PMID:37963210
      reference_title: The Chromatin Remodeler CHD4 Sustains Ewing Sarcoma Cell Survival by Controlling Global Chromatin Architecture.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: CHD4 silencing induced tumor cell death by apoptosis and abolished colony formation.
      explanation: >-
        Functional depletion establishes a cell-survival dependency.
- name: Context-Dependent BRCA1 Repair Impairment
  mechanism_confidence: PROVISIONAL
  description: >-
    Enrichment of BRCA1 at elongating transcription machinery can reduce its availability for damage
    repair in Ewing cell models. Other experiments found no apparent HR defect and attributed PARP
    sensitivity to trapped PARP-DNA complexes. These observations constrain the scope of an HR-deficiency
    model rather than establishing either uniform HR proficiency or uniform clinical BRCAness. PARP
    trapping and context-dependent HR impairment can coexist.
  notes: >-
    Conformance to dna_repair_synthetic_lethality#PARP and Platinum Synthetic Lethality
    was withdrawn when the former bundled replication-stress node was split. That module
    presupposes HRR-deficient tumor cells with a PARP/platinum synthetic-lethal vulnerability.
    Context-dependent BRCA1 impairment and PARP-trapping sensitivity in the cited Ewing
    models do not establish that broader therapeutic phenotype across Ewing sarcoma.
    This withdrawal preserves both the positive BRCA1 findings and the contrary HR-assay
    results without asserting uniform HR deficiency or platinum/PARP clinical benefit.
  evidence:
  - reference: PMID:29513652
    reference_title: EWS-FLI1 increases transcription to cause R-loops and block BRCA1 repair in Ewing sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: In addition, homologous recombination is impaired in Ewing sarcoma owing to an enriched interaction between BRCA1 and the elongating transcription machinery.
    explanation: >-
      Supports BRCA1 sequestration and impaired HR in the studied Ewing models.
  - reference: PMID:26505995
    reference_title: "Combinations of PARP Inhibitors with Temozolomide Drive PARP1 Trapping and Apoptosis in Ewing's Sarcoma."
    supports: REFUTE
    evidence_source: IN_VITRO
    snippet: Here, we show that PARP inhibitor sensitivity in Ewing's sarcoma cells is not through an apparent defect in DNA repair by HR, but through hypersensitivity to trapped PARP1-DNA complexes.
    explanation: >-
      A separate cellular study found HR proficiency and implicated PARP trapping; differences in
      assays and conditions remain relevant.
  genes:
  - preferred_term: BRCA1
    term:
      id: hgnc:1100
      label: BRCA1
  biological_processes:
  - preferred_term: double-strand break repair via homologous recombination
    modifier: DECREASED
    term:
      id: GO:0000724
      label: double-strand break repair via homologous recombination
- name: SLFN11-Dependent Replication Fork Arrest
  description: >-
    EWS-FLI1 directly increases SLFN11 expression. SLFN11 blocks stressed replication forks and promotes
    susceptibility to DNA-damaging agents. Expression-outcome correlations are not a validated standalone
    clinical selection test. Loss of SLFN11 can confer treatment resistance and is associated with
    metabolic adaptation in Ewing models.
  evidence:
  - reference: PMID:25779942
    reference_title: SLFN11 Is a Transcriptional Target of EWS-FLI1 and a Determinant of Drug Response in Ewing Sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: EWS-FLI1 binds near the transcription start site of SLFN11 promoter and acts as a positive regulator of SLFN11 expression in Ewing sarcoma cells.
    explanation: >-
      Direct promoter binding and expression perturbation support fusion-driven SLFN11 transcription.
  - reference: PMID:29395061
    reference_title: SLFN11 Blocks Stressed Replication Forks Independently of ATR.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Unlike ATR, SLFN11 neither interferes with the loading of CDC45 and PCNA nor inhibits the initiation of DNA replication but selectively blocks fork progression while inducing chromatin opening across replication initiation sites.
    explanation: >-
      Mechanistic fork-blocking experiments in cancer cell models provide complementary, not exclusively
      Ewing-specific, support.
  genes:
  - preferred_term: SLFN11
    term:
      id: hgnc:26633
      label: SLFN11
  biological_processes:
  - preferred_term: DNA replication
    modifier: DECREASED
    term:
      id: GO:0006260
      label: DNA replication
- name: USP1-Survivin Stress Buffering
  mechanism_confidence: PROVISIONAL
  description: >-
    EWS-FLI1 increases USP1 expression. USP1 stabilizes survivin and buffers replication-stress-associated
    apoptosis, allowing continued Ewing cell survival. USP1 inhibition sensitizes cells to doxorubicin
    and etoposide in preclinical experiments; human efficacy has not been established.
  evidence:
  - reference: PMID:37478161
    reference_title: "USP1 Expression Driven by EWS::FLI1 Transcription Factor Stabilizes Survivin and Mitigates Replication Stress in Ewing Sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Together, our study demonstrates that USP1 is regulated by EWS::FLI1, the USP1-Survivin axis promotes EWS cell survival, and USP1 inhibition sensitizes cells to standard of care chemotherapy.
    explanation: >-
      Ewing cellular experiments support a distinct fusion-regulated stress-buffering pathway.
  genes:
  - preferred_term: USP1
    term:
      id: hgnc:12607
      label: USP1
  - preferred_term: BIRC5
    term:
      id: hgnc:593
      label: BIRC5
  downstream:
  - target: Tumor Cell Proliferation and Survival
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    hypothesis_groups:
    - replication_stress_vulnerability_model
    description: >-
      USP1-dependent survivin stabilization suppresses stress-associated apoptosis.
    evidence:
    - reference: PMID:37478161
      reference_title: "USP1 Expression Driven by EWS::FLI1 Transcription Factor Stabilizes Survivin and Mitigates Replication Stress in Ewing Sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Together, our study demonstrates that USP1 is regulated by EWS::FLI1, the USP1-Survivin axis promotes EWS cell survival, and USP1 inhibition sensitizes cells to standard of care chemotherapy.
      explanation: >-
        Ewing cellular experiments support a distinct fusion-regulated stress-buffering pathway.
    intermediate_mechanisms:
    - survivin stabilization
- name: Proposed POLQ Splicing and MMEJ Defect
  mechanism_confidence: PROVISIONAL
  description: >-
    A 2025 bioRxiv preprint reports that EWS-FLI1 expression or EWSR1 loss induces POLQ exon 25 skipping,
    reduces polymerase theta protein, and impairs microhomology-mediated end joining. Fusion knockdown
    and POLQ rescue support causality in tested models. Proposed synthetic lethality with other repair
    pathways requires independent replication and clinical evaluation; this is an emerging additional
    repair defect rather than a reason to erase the BRCA1 literature.
  genes:
  - preferred_term: POLQ
    term:
      id: hgnc:9186
      label: POLQ
  biological_processes:
  - preferred_term: alternative mRNA splicing, via spliceosome
    modifier: ABNORMAL
    term:
      id: GO:0000380
      label: alternative mRNA splicing, via spliceosome
  evidence:
  - reference: PMID:40568108
    reference_title: Disruption of Microhomology-mediated End-joining in Ewing Sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Expression of EWS-FLI1, or loss of EWSR1, causes exon 25 skipping of the POLQ transcript, decreased POLΘ expression, impaired MMEJ, and cellular sensitivity to inhibitors of the Fanconi Anemia (FA), NHEJ, or HR pathways, through the mechanism of synthetic lethality.
    explanation: >-
      A 2025 bioRxiv preprint reports altered POLQ splicing and rescue experiments. This remains
      provisional and does not establish efficacy of the proposed inhibitors in patients.
- name: SLFN11-Loss-Associated Lipid Remodeling
  mechanism_confidence: PROVISIONAL
  description: >-
    SLFN11-deficient Ewing models show reduced GPD2 expression and increased glycerophospholipid
    biosynthesis. Pharmacologic inhibition of glycerophospholipid synthesis increased SN-38 sensitivity
    in vitro, with modest and cell-line-dependent combination effects. The regulatory link from SLFN11
    loss to GPD2 suppression and human predictive value remain unresolved. This loss state is not
    represented as a positive consequence of SLFN11 fork arrest.
  biological_processes:
  - preferred_term: glycerophospholipid biosynthetic process
    modifier: INCREASED
    term:
      id: GO:0046474
      label: glycerophospholipid biosynthetic process
  evidence:
  - reference: PMID:41620417
    reference_title: Targeting glycerophospholipid biosynthesis overcomes chemoresistance driven by SLFN11 loss in Ewing sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Here, we leverage transcriptomic and metabolomic profiling in patient-derived EWS models to demonstrate that SLFN11 loss drives downregulated mitochondrial glycerol-3-phosphate dehydrogenase (GPD2) expression, higher accumulation of glycerol-3-phosphate, fatty acid unsaturation, and enhanced glycerophospholipid (GPL) biosynthesis.
    explanation: >-
      SLFN11 knockout and multi-omics support lipid remodeling in Ewing models. The molecular route
      to GPD2 suppression was not resolved.
  downstream:
  - target: Tumor Cell Proliferation and Survival
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - replication_stress_vulnerability_model
    description: >-
      Metabolic adaptation can support survival under genotoxic therapy in SLFN11-deficient cellular
      models.
    evidence:
    - reference: PMID:41620417
      reference_title: Targeting glycerophospholipid biosynthesis overcomes chemoresistance driven by SLFN11 loss in Ewing sarcoma.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Subsequently, targeting GPL biosynthesis (FSG67) restored DNA-damaging agent (SN-38) sensitivity in SLFN11-deficient EWS model, revealing a potential metabolic vulnerability to overcome chemoresistance.
      explanation: >-
        Preclinical pharmacologic sensitization supports a candidate resistance adaptation, not an
        established treatment.
- name: PARP1-Supported Fusion Transcription
  mechanism_confidence: PROVISIONAL
  description: >-
    PARP1 interacts with EWS-FLI1 and EWS-ERG and supports fusion-mediated transcription; EWS-FLI1
    also maintains PARP1 expression. This experimentally reported feedback connects transcription
    and damage response. The preclinical drug rationale has not translated into uniform clinical
    response.
  evidence:
  - reference: PMID:22287547
    reference_title: "PARP-1 inhibition as a targeted strategy to treat Ewing's sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Notably, EWS-FLI1 fusion genes acted in a positive feedback loop to maintain the expression of PARP1, which was required for EWS-FLI-mediated transcription, thereby enforcing oncogene-dependent sensitivity to PARP-1 inhibition.
    explanation: >-
      Ewing cellular studies support reciprocal dependence of fusion transcription and PARP1.
  genes:
  - preferred_term: PARP1
    term:
      id: hgnc:270
      label: PARP1
  downstream:
  - target: GGAA Microsatellite Enhancer Reprogramming
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - replication_stress_vulnerability_model
    description: >-
      PARP1 supports the broader fusion transcriptional program; a specific requirement at every
      GGAA enhancer has not been demonstrated.
    evidence:
    - reference: PMID:22287547
      reference_title: "PARP-1 inhibition as a targeted strategy to treat Ewing's sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Notably, EWS-FLI1 fusion genes acted in a positive feedback loop to maintain the expression of PARP1, which was required for EWS-FLI-mediated transcription, thereby enforcing oncogene-dependent sensitivity to PARP-1 inhibition.
      explanation: >-
        Ewing cellular studies support reciprocal dependence of fusion transcription and PARP1.
- name: Tumor-Stroma IL-6/STAT3 Signaling
  mechanism_confidence: PROVISIONAL
  description: >-
    In flow-perfusion coculture, mesenchymal stromal cells and Ewing tumor cells respond to biophysical
    cues through IL-6/STAT3 signaling and altered drug response. This established-tumor microenvironment
    mechanism is distinct from IGF-1/YAP1 developmental initiation.
  biological_processes:
  - preferred_term: interleukin-6-mediated signaling pathway
    modifier: INCREASED
    term:
      id: GO:0070102
      label: interleukin-6-mediated signaling pathway
  cell_types:
  - preferred_term: mesenchymal stem cell
    term:
      id: CL:0000134
      label: mesenchymal stem cell
  evidence:
  - reference: PMID:27923328
    reference_title: Modeling Stroma-Induced Drug Resistance in a Tissue-Engineered Tumor Model of Ewing Sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Here, we demonstrate that these same biophysical cues-modeled by coculturing ES cells and mesenchymal stem cells (MSCs) in 3D scaffolds within a flow perfusion bioreactor-activate interleukin-6 and transcription factor Stat3.
    explanation: >-
      A tissue-engineered tumor-stroma coculture demonstrates IL-6/STAT3 activation under biophysical
      stimulation.
  downstream:
  - target: Tumor Cell Proliferation and Survival
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      Stromal cytokine signaling modifies tumor-cell survival and drug response in a tissue-engineered
      model.
    evidence:
    - reference: PMID:27923328
      reference_title: Modeling Stroma-Induced Drug Resistance in a Tissue-Engineered Tumor Model of Ewing Sarcoma.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Here, we demonstrate that these same biophysical cues-modeled by coculturing ES cells and mesenchymal stem cells (MSCs) in 3D scaffolds within a flow perfusion bioreactor-activate interleukin-6 and transcription factor Stat3.
      explanation: >-
        A tissue-engineered tumor-stroma coculture demonstrates IL-6/STAT3 activation under biophysical
        stimulation.
    intermediate_mechanisms:
    - IL-6/STAT3 activation
- name: Hybrid Mesenchymal Tumor States and Matrix Deposition
  description: >-
    Ewing tumors contain coexisting gene-regulatory programs. CD73-positive malignant subpopulations
    can retain fusion-activated genes while expressing normally repressed mesenchymal and extracellular-matrix
    genes. These CAF-like tumor cells deposit matrix near tumor borders and invasive foci. Their
    presence is not proof of a separate fibroblast lineage, and a universal binary fusion-high/fusion-low
    switch does not capture the observed heterogeneity.
  biological_processes:
  - preferred_term: extracellular matrix organization
    modifier: INCREASED
    term:
      id: GO:0030198
      label: extracellular matrix organization
  evidence:
  - reference: PMID:40667384
    reference_title: Multimodal single-cell analyses reveal distinct fusion-regulated transcriptional programs in Ewing sarcoma.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: When we examined primary EwS patient tumors, we observed these same regulatory modules were variably enriched both across and within tumors, highlighting the existence of intratumoral heterogeneity in gene regulatory networks.
    explanation: >-
      Single-cell RNA/ATAC analyses identify multiple coexisting regulatory programs rather than
      a single binary fusion-high/fusion-low axis.
  - reference: PMID:37471463
    reference_title: Cancer-Associated Fibroblast-Like Tumor Cells Remodel the Ewing Sarcoma Tumor Microenvironment.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: These cells retained expression of the fusion-activated gene signature alongside high expression of genes that are normally repressed by EWS::FLI1.
    explanation: >-
      CD73-positive CAF-like tumor cells can occupy hybrid transcriptional states; they are malignant
      cells, not automatically nonmalignant fibroblasts.
  - reference: PMID:37471463
    reference_title: Cancer-Associated Fibroblast-Like Tumor Cells Remodel the Ewing Sarcoma Tumor Microenvironment.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Thus, these EwS cells gained mesenchymal properties, including the capacity to deposit ECM, without losing proliferative or tumorigenic potential.
    explanation: The source directly links the hybrid malignant-cell state to extracellular-matrix deposition. The annotation does not relabel these malignant cells as ordinary fibroblasts.
- name: Osseous Tumor Expansion and Bone Destruction
  description: >-
    In osseous Ewing sarcoma, infiltrative tumor growth destroys the affected bone and can extend
    through cortex into soft tissue. Local structural injury contributes to pain, swelling and fracture
    risk. These consequences are specific to osseous or bone-involving disease; treatment can also
    contribute to later fractures.
  locations:
  - preferred_term: bone tissue
    term:
      id: UBERON:0002481
      label: bone tissue
  notes: >-
    Bone tissue is already explicitly bound to UBERON:0002481. The cited radiographic
    destruction does not isolate osteoclast-mediated resorption, so no osteoclast cell-type
    or bone-resorption process annotation is inferred from this imaging observation.
  evidence:
  - reference: PMID:25691401
    reference_title: "Diagnosis and treatment of Ewing sarcoma of the bone: a review article."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: In ES of the bone, plain radiographs exhibit permeative and infiltrative destruction of the affected bone
    explanation: >-
      Clinical imaging review supports a destructive osseous growth mechanism, distinct from extraskeletal
      disease.
  downstream:
  - target: Bone Pain
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - local tissue injury and nociceptive stimulation
    description: >-
      Destructive local tumor growth can produce pain; the precise nociceptive pathway is not inferred
      from a specific molecular study.
    evidence:
    - reference: PMID:25691401
      reference_title: "Diagnosis and treatment of Ewing sarcoma of the bone: a review article."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Patients with ES exhibit local symptoms such as tumor mass formation, induration, pain, swelling, venous dilation, and hyperemia.
      explanation: >-
        Clinical review connects local growth with pain and swelling.
  - target: Pathologic Fracture
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - loss of structural bone integrity
    description: >-
      Bone involvement weakens the skeleton and predisposes to fracture. Disease-related and post-treatment
      fractures require separate interpretation.
    evidence:
    - reference: PMID:11902298
      reference_title: Fractures in pediatric Ewing sarcoma.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Fracture occurred in 14 (15%) of 93 patients with long-bone ESFT, most commonly in the femur.
      explanation: >-
        Retrospective long-bone cohort supports the complication, with restricted anatomy and historical
        treatment.
- name: EZH2-Associated Differentiation Repression
  description: >-
    EWS-FLI1 induces EZH2, which contributes to repression of differentiation-associated genes and
    maintenance of an undifferentiated state. Genetic depletion impairs clonogenicity and tumorigenicity
    in preclinical systems. This dependency is distinct from the heterogeneous PRC2 changes following
    STAG2 loss and does not imply that every Ewing tumor will respond to an EZH2 inhibitor.
  genes:
  - preferred_term: EZH2
    term:
      id: hgnc:3527
      label: EZH2
  evidence:
  - reference: PMID:19289832
    reference_title: EZH2 is a mediator of EWS/FLI1 driven tumor growth and metastasis blocking endothelial and neuro-ectodermal differentiation.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Here, we found EWS/FLI1 bound to the EZH2 promoter in vivo, and induced EZH2 expression in ET and mesenchymal stem cells.
    explanation: >-
      Chromatin binding and expression experiments support fusion-associated EZH2 induction; in vivo
      here describes binding within cells, not an animal efficacy result.
  - reference: PMID:19289832
    reference_title: EZH2 is a mediator of EWS/FLI1 driven tumor growth and metastasis blocking endothelial and neuro-ectodermal differentiation.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Subsequent microarray analysis of EZH2 knock down, HDAC-inhibitor treatment and confirmation in independent assays revealed an undifferentiated phenotype maintained by EZH2 in ET.
    explanation: >-
      Cellular perturbation supports maintenance of an undifferentiated transcriptional state.
  downstream:
  - target: Blocked Differentiation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - repression of differentiation-associated genes
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      EZH2-associated repression maintains an undifferentiated state in Ewing experimental systems.
    evidence:
    - reference: PMID:19289832
      reference_title: EZH2 is a mediator of EWS/FLI1 driven tumor growth and metastasis blocking endothelial and neuro-ectodermal differentiation.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Subsequent microarray analysis of EZH2 knock down, HDAC-inhibitor treatment and confirmation in independent assays revealed an undifferentiated phenotype maintained by EZH2 in ET.
      explanation: >-
        Cellular perturbation supports maintenance of an undifferentiated transcriptional state.
- name: HOXD13-Driven Mesenchymal Plasticity
  mechanism_confidence: PROVISIONAL
  description: >-
    Fusion-created enhancer activity at the HOXD locus induces a developmental transcriptional program.
    HOXD13 activates some genes normally repressed by EWS-FLI1 and shifts cells toward mesenchymal
    and migratory states. This provides a defined modifier of the differentiation block and contributes
    to a continuum of tumor states.
  genes:
  - preferred_term: HOXD13
    term:
      id: hgnc:5136
      label: HOXD13
  evidence:
  - reference: PMID:35653119
    reference_title: "EWS::FLI1 and HOXD13 Control Tumor Cell Plasticity in Ewing Sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: We found that EWS::FLI1 creates a de novo GGAA microsatellite enhancer in a developmentally conserved regulatory region of the HOXD locus.
    explanation: >-
      Enhancer perturbation supports fusion-dependent HOXD locus activation.
  - reference: PMID:35653119
    reference_title: "EWS::FLI1 and HOXD13 Control Tumor Cell Plasticity in Ewing Sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: More strikingly, HOXD13 bound and activated EWS::FLI1-repressed genes, leading to adoption of mesenchymal and migratory cell states that are normally suppressed by the fusion.
    explanation: >-
      Supports transcriptional antagonism and a mesenchymal-state modifier rather than uniformly
      blocked differentiation.
  downstream:
  - target: Hybrid Mesenchymal Tumor States and Matrix Deposition
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - canonical_fusion_enhanceropathy_model
    description: >-
      HOXD13-mediated antagonism contributes to the mesenchymal transcriptional continuum. It is
      one candidate contributor to hybrid states, not a demonstrated sole cause of CD73 expression
      or matrix deposition.
    evidence:
    - reference: PMID:35653119
      reference_title: "EWS::FLI1 and HOXD13 Control Tumor Cell Plasticity in Ewing Sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: More strikingly, HOXD13 bound and activated EWS::FLI1-repressed genes, leading to adoption of mesenchymal and migratory cell states that are normally suppressed by the fusion.
      explanation: >-
        Supports transcriptional antagonism and a mesenchymal-state modifier rather than uniformly
        blocked differentiation.
- name: BARD1-Loss and GBP1-Associated DNA-Damage Sensitivity
  mechanism_confidence: PROVISIONAL
  biological_scale: CELLULAR
  description: >-
    A BARD1-variant patient-derived Ewing cell line and BARD1-depletion experiments show enhanced
    sensitivity to PARP inhibition and radiation. BARD1 loss can increase GBP1 expression, which
    contributes to damage-induced apoptosis in the tested cells. Other signals also induce GBP1,
    so expression is not a specific BARD1-loss marker. This is a bounded experimental modifier of
    treatment response; neither disease-wide BARD1 prevalence, penetrant inherited Ewing
    susceptibility nor a validated clinical predictive biomarker is established.
  evidence:
  - reference: PMID:36187937
    reference_title: BRCA1-associated RING domain-1 (BARD1) loss and GBP1 expression enhance sensitivity to DNA damage in Ewing sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: We demonstrate that PSaRC318 cells, a novel patient-derived cell line harboring a pathogenic BARD1 variant, are sensitive to PARP inhibition and by testing the effect of BARD1 depletion in additional Ewing sarcoma cell lines, we confirm that BARD1 loss enhances cell sensitivity to PARP inhibition plus radiation.
    explanation: >-
      Patient-derived and BARD1-depleted cell models support an experimental modifier, not a
      validated patient biomarker or a ten-percent BARD1 frequency.
  - reference: PMID:36187937
    reference_title: BRCA1-associated RING domain-1 (BARD1) loss and GBP1 expression enhance sensitivity to DNA damage in Ewing sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Here, we demonstrate that GBP1 contributes to the enhanced sensitivity of BARD1 deficient Ewing cells to DNA damage.
    explanation: >-
      GBP1 knockdown reduced radiation- and niraparib-associated apoptosis in PSaRC318 cells; GBP1
      expression is not specific to BARD1 loss.
  genes:
  - preferred_term: BARD1
    term:
      id: hgnc:952
      label: BARD1
  - preferred_term: GBP1
    term:
      id: hgnc:4182
      label: GBP1
mechanistic_hypotheses:
- hypothesis_group_id: canonical_fusion_enhanceropathy_model
  hypothesis_label: Canonical EWS-FLI1 fusion enhanceropathy model
  status: CANONICAL
  description: >-
    The canonical fusion transcriptional program includes BAF-supported GGAA enhancer activation,
    NuRD/LSD1-associated repression, core regulatory circuitry, impaired differentiation and metabolic
    rewiring. CHD4-mediated structural maintenance is a separate survival dependency. Dynamic endogenous
    hubs are a preprint-supported refinement. Fusion dosage and multiple coexisting regulatory modules
    create plasticity; most mechanistic experiments concern EWSR1::FLI1 rather than every FET-ETS
    partner.
  evidence:
  - reference: PMID:25453903
    reference_title: "EWS-FLI1 utilizes divergent chromatin remodeling mechanisms to directly activate or repress enhancer elements in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Our findings demonstrate how EWS-FLI1 establishes an oncogenic regulatory program governing both tumor survival and differentiation."
    explanation: Supports the canonical fusion enhanceropathy model.
  - reference: PMID:41659683
    reference_title: "Dynamic regulation of endogenous transcription factor hubs at single-molecule resolution."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We found that endogenous EWS::FLI1 forms dynamic, sub-diffraction-limit hubs with mechanisms of dissolution that prevent the hubs from achieving macroscopic liquid-liquid phase separation."
    explanation: >-
      Endogenous hub imaging is reported in a bioRxiv preprint and is retained as a provisional refinement,
      not independently established consensus.
  - reference: PMID:23178492
    reference_title: "Mechanism and relevance of EWS/FLI-mediated transcriptional repression in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Importantly, we demonstrated that the repressive function of EWS/FLI is absolutely required for the oncogenic function of the fusion."
    explanation: Supports including direct transcriptional repression in the canonical mechanism.
  - reference: PMID:40215343
    reference_title: "(GGAA)(3)-Based TF-PROTACs Enable Targeted Degradation of ETV6 to Inhibit Ewing Sarcoma Growth."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Recent studies identified ETV6 as a vulnerability in Ewing sarcoma, where it competes with EWS::FLI1 at short GGAA repeats to restrain EWS::FLI1 function."
    explanation: Supports ETV6 as a counter-regulatory modifier of the GGAA enhanceropathy.
- hypothesis_group_id: cell_of_origin_context_model
  hypothesis_label: Permissive developmental cell-of-origin model
  status: EMERGING
  description: >-
    Developmental timing and cell state influence fusion tolerance and transformation in human progenitor
    and animal models. Neural crest and early mesenchymal systems are experimentally permissive,
    but no unique human lineage or age of initiation is proven. IGF-1/YAP1 cooperation is established
    in a particular mouse-cell model, and inherited GGAA architecture modifies susceptibility at
    specific loci without establishing a universal permissive genotype.
  evidence:
  - reference: PMID:41136396
    reference_title: "EWS::FLI1 expression in human embryonic mesenchymal stem cells leads to transcriptional reprograming, defective DNA damage repair and Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "In summary, we show that EWS::FLI1 enforces an aberrant transcriptome and solely is able to endow transforming capacity when expressed in undifferentiated, early heMSCs."
    explanation: Supports the developmental-context hypothesis in embryonic mesenchymal stem cells.
  - reference: PMID:40080499
    reference_title: "YAP1 is a key regulator of EWS::FLI1-dependent malignant transformation upon IGF-1-mediated reprogramming of bone mesenchymal stem cells."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We report that transient exposure to IGF-1 concentrations mimicking serum levels during puberty reprograms limb-derived mesenchymal cells of EWS::FLI1-mutant mice to stable transformation and tumorigenicity."
    explanation: Supports IGF-1/YAP1 signaling as a developmental cooperating mechanism.
  - reference: PMID:36787739
    reference_title: "Targeted long-read sequencing of the Ewing sarcoma 6p25.1 susceptibility locus identifies germline-somatic interactions with EWSR1-FLI1 binding."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We propose that germline microsatellite variation at the 6p25.1 EwS susceptibility locus could impact downstream gene expression and EwS biology."
    explanation: Supports inherited GGAA microsatellite architecture as part of the permissive-context model.
- hypothesis_group_id: replication_stress_vulnerability_model
  hypothesis_label: Transcription-coupled replication stress vulnerability model
  status: EMERGING
  description: >-
    A superimposed vulnerability framework links fusion-driven R-loops, TOP1-stress-dependent DHX9
    sequestration, context-dependent BRCA1 impairment, SLFN11 fork arrest, PARP1-supported transcription
    and USP1-survivin stress buffering. A POLQ/MMEJ defect is supported by a preprint, and SLFN11-loss-associated
    lipid remodeling is a candidate resistance route. These mechanisms complement the canonical fusion
    model; experimental sensitivities do not establish uniform clinical HR deficiency or PARP-inhibitor
    benefit.
  evidence:
  - reference: PMID:29513652
    reference_title: "EWS-FLI1 increases transcription to cause R-loops and block BRCA1 repair in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Here we show that Ewing sarcoma cells display alterations in regulation of damage-induced transcription, accumulation of R-loops and increased replication stress."
    explanation: Supports R-loop accumulation and replication stress downstream of EWS-FLI1 activity.
  - reference: PMID:40721661
    reference_title: "EWS::FLI1-DHX9 interaction promotes Ewing sarcoma sensitivity to DNA topoisomerase 1 poisons by altering R-loop metabolism."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We discovered that EWS::FLI1 prevents the resolution of R-loops induced by these drugs via sequestering DHX9 helicase, ultimately resulting in R-loop accumulation, replication stress, and genome instability."
    explanation: Supports the DHX9-dependent R-loop arm of the vulnerability model.
  - reference: PMID:25779942
    reference_title: "SLFN11 Is a Transcriptional Target of EWS-FLI1 and a Determinant of Drug Response in Ewing Sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "RESULTS: EWS-FLI1 binds near the transcription start site of SLFN11 promoter and acts as a positive regulator of SLFN11 expression in Ewing sarcoma cells."
    explanation: Supports direct EWS-FLI1 activation of SLFN11 within this vulnerability model.
- hypothesis_group_id: cohesin_modified_high_risk_model
  hypothesis_label: STAG2/cohesin-modified high-risk enhancer model
  status: EMERGING
  description: >-
    STAG2 loss modifies fusion-dependent and independent chromatin contacts, PRC2 regulation and
    metastatic behavior. Repeat-class redistribution and selective multimeric enhancer amplification
    are supported by one recent perturbation study; earlier chromatin-contact studies are related
    but not exact independent replications. Prognostic associations depend on cohort and assay. COG
    diagnostic protein-loss/EFS data and Japanese sequencing/post-profiling-OS data measure different
    exposures and endpoints; the Japanese cohort had only three STAG2-mutant tumors. Their difference
    does not demonstrate an ancestry-specific mechanism or refute the COG association.
  evidence:
  - reference: PMID:41950086
    reference_title: "STAG2 loss amplifies EWS-FLI1-driven microsatellite enhancer activity promoting Ewing sarcoma aggressiveness."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Together, these findings reveal that STAG2 loss reprograms, rather than globally attenuates, EWS-FLI1 function, amplifying a high-risk oncogenic transcriptional state in Ewing sarcoma."
    explanation: Supports the STAG2-modified high-risk enhancer model.
  - reference: PMID:39487368
    reference_title: "STAG2 loss in Ewing sarcoma alters enhancer-promoter contacts dependent and independent of EWS::FLI1."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Subsequent genomic profiling and high-resolution chromatin interaction data from Capture Hi-C indicated that cohesin-STAG2 facilitates communication between EWS::FLI1-bound long GGAA repeats, presumably acting as neoenhancers, and their target promoters."
    explanation: Supports STAG2-dependent enhancer-promoter communication at long GGAA repeats.
  - reference: PMID:36221002
    reference_title: "Adverse prognostic impact of the loss of STAG2 protein expression in patients with newly diagnosed localised Ewing sarcoma: A report from the Children's Oncology Group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among patients with localised disease, 5-year event-free survival was 54% (95% CI 34-70%) and 75% (95% CI 63-84%) for patients with STAG2 loss vs. expression (P = 0.0034)."
    explanation: Supports the high-risk clinical association for STAG2 protein loss.
  - reference: PMID:41206913
    reference_title: "Analysis of comprehensive genomic profiling test for Ewing sarcoma in pediatric patients and adults using the nationwide clinical and genomic database in Japan."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "There was no significant difference in overall survival after genomic profiling test enrollment for STAG2 and TP53 mutations (P = .663 and P = .767), but those with CDKN2A and CDKN2B deletions had poor prognosis (P = .024 and P = .012)."
    explanation: >-
      The 81-patient Japanese profiling cohort found no significant STAG2 mutation association with
      post-enrollment OS. With only three STAG2-mutant cases and a different assay, endpoint and
      enrollment setting, this is not an ancestry-effect test or a direct replication of the COG
      diagnostic IHC analysis.
histopathology:
- name: Small Round Cell Tumor
  finding_term:
    preferred_term: Ewing Sarcoma
    term:
      id: NCIT:C4817
      label: Ewing Sarcoma
  frequency: VERY_FREQUENT
  description: Ewing sarcoma is a small round cell tumor of bone or soft tissue.
  notes: >-
    Local NCIT places Ewing Sarcoma under both morphologic finding and neoplasm by special category
    hierarchies, and its definition explicitly captures the small round cell morphology.
  evidence:
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Histologically, most cases are made up of solid sheets of uniform small round cells with round nuclei containing finely stippled chromatin, inconspicuous nucleoli, and scant clear or eosinophilic cytoplasm, with ill-defined cell borders
    explanation: >-
      The guideline describes characteristic morphology without asserting a proven neuroectodermal
      human origin.
- name: Homer Wright Rosette-like Formation
  finding_term:
    preferred_term: Homer Wright Rosette Formation
    term:
      id: NCIT:C35942
      label: Homer Wright Rosette Formation
  frequency: OCCASIONAL
  description: >-
    Atypical Ewing sarcoma of bone can show rosette-like textures resembling Homer-Wright rosettes,
    reflecting neuroectodermal differentiation features in a minority of cases rather than a required
    diagnostic feature.
  evidence:
  - reference: PMID:3113717
    reference_title: "Small round blue cell sarcoma of bone mimicking atypical Ewing's sarcoma with neuroectodermal features. An analysis of five cases with immunohistochemical and electron microscopic support."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ewing's sarcoma (ES) of bone may occasionally display rosette-like textures mimicking Homer-Wright ones, as seen in neuroectodermic neoplasms (neuroblastoma, peripheral neuroepithelioma)."
    explanation: >-
      Supports Homer Wright rosette-like formation as an occasional histopathologic pattern in atypical
      Ewing sarcoma of bone.
- name: High Grade Tumor
  finding_term:
    preferred_term: high grade
    term:
      id: NCIT:C14158
      label: High Grade
  frequency: VERY_FREQUENT
  description: >-
    Ewing sarcoma is managed as a high-grade sarcoma. Its small round cell morphology does not imply
    indolent disease; stage and treatment response provide additional risk information.
  evidence:
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: the NCCN, ESMO and British Sarcoma Group (BSG) guidelines follow-up recommendations for high-grade sarcomas, including ES, vary
    explanation: >-
      The guideline explicitly includes Ewing sarcoma among high-grade sarcomas.
- name: Post-Chemotherapy Tumor Necrosis
  finding_term:
    preferred_term: tumor cell necrosis
    term:
      id: NCIT:C35957
      label: Tumor Cell Necrosis
  description: >-
    Tumor cell necrosis can be assessed in Ewing sarcoma resection specimens, especially after neoadjuvant
    chemotherapy. The degree of tumor necrosis is a clinically meaningful histologic response marker:
    greater than or equal to 90% tumor necrosis defines a good chemotherapy response in many studies
    and is associated with improved local recurrence-free survival.
  evidence:
  - reference: PMID:17177205
    reference_title: "Chemotherapy response is an important predictor of local recurrence in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with a good response to chemotherapy (> or = 90% tumor necrosis), had superior LRFS at 5 years (86% vs 51%, P = .015)."
    explanation: >-
      Supports post-chemotherapy tumor necrosis as an Ewing sarcoma histologic-response measure with
      prognostic significance.

phenotypes:
- category: Musculoskeletal
  name: Bone Pain
  frequency: FREQUENT
  diagnostic: true
  description: >-
    Localized bone pain is a common presenting symptom of osseous disease, sometimes intermittent
    or initially attributed to strain. Frequency varies with age, site and ascertainment; the cited
    75.3% estimate is from a single-center adult cohort, not a universal pediatric estimate.
  phenotype_term:
    preferred_term: Bone pain
    term:
      id: HP:0002653
      label: Bone pain
  evidence:
  - reference: PMID:34235109
    reference_title: "Outcomes of Adult Ewing Sarcoma Treated with Multimodality Therapy: A Single-Institute Experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pain (75.3%) was the most common symptom at presentation."
    explanation: >-
      A 73-patient cohort restricted to adults reported pain in 75.3%; this supports the within-cohort
      frequency and common clinical presentation.
- category: Musculoskeletal
  name: Soft Tissue Mass / Localized Swelling
  diagnostic: true
  description: >-
    A palpable mass or localized swelling may develop as tumor extends through the bone cortex into
    surrounding soft tissues. The mass is often firm and may be tender or warm, and may initially
    be attributed to trauma or infection.
  phenotype_term:
    preferred_term: Soft tissue neoplasm
    term:
      id: HP:0031459
      label: Soft tissue neoplasm
  evidence:
  - reference: PMID:34235109
    reference_title: "Outcomes of Adult Ewing Sarcoma Treated with Multimodality Therapy: A Single-Institute Experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: In this study, pain and swelling were the most common presenting complaints seen in 75.3% and 42.5% patients, respectively
    explanation: >-
      Adult single-center cohort supports swelling as a common presentation; no universal VERY_FREQUENT
      estimate is inferred.
- category: Constitutional
  name: Fever
  description: >-
    Fever is a possible constitutional symptom. Inflammatory presentations may overlap with osteomyelitis;
    fever is neither required nor specific for Ewing sarcoma.
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
  evidence:
  - reference: PMID:34485689
    reference_title: "Educational Case: Ewing Sarcoma of Bone."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: When present, constitutional symptoms include unintentional weight loss, fatigue, anemia, and fevers.
    explanation: >-
      The didactic article general clinical discussion supports these nonspecific manifestations.
      This quote is not an observation in its fictional teaching case, and no symptom-specific frequency
      is inferred.
- category: Constitutional
  name: Weight Loss
  description: >-
    Unintentional weight loss can accompany Ewing sarcoma as a nonspecific constitutional symptom.
    No individual weight-loss frequency is established by the cited general clinical discussion.
  phenotype_term:
    preferred_term: Weight loss
    term:
      id: HP:0001824
      label: Weight loss
  evidence:
  - reference: PMID:34485689
    reference_title: "Educational Case: Ewing Sarcoma of Bone."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: When present, constitutional symptoms include unintentional weight loss, fatigue, anemia, and fevers.
    explanation: >-
      The didactic article general clinical discussion supports these nonspecific manifestations.
      This quote is not an observation in its fictional teaching case, and no symptom-specific frequency
      is inferred.
- category: Systemic
  name: Metastatic Disease
  frequency: OCCASIONAL
  description: >-
    About one quarter of patients have detectable metastases at diagnosis, predominantly in lung,
    bone and bone marrow. Prognosis depends on metastatic distribution, age and treatment. In the
    metastatic AEWS1221 trial, three-year event-free survival was 37.4% with VDC/IE and 39.1% with
    added ganitumab; these estimates are not five-year overall survival.
  phenotype_term:
    preferred_term: Neoplasm
    term:
      id: HP:0002664
      label: Neoplasm
  notes: >-
    HPO searches for metastasis and metastatic did not identify a disease-agnostic
    metastatic-neoplasm term; retrieved narrower terms describe other specific tumors
    or imaging findings. HP:0002664 is a broad neoplasm anchor, not an exact encoding
    of metastatic spread. The Ewing-specific meaning is retained in the phenotype name,
    description and metastatic-stage entry.
  evidence:
  - reference: PMID:34235109
    reference_title: "Outcomes of Adult Ewing Sarcoma Treated with Multimodality Therapy: A Single-Institute Experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among 21 (28.8%) patients, the lung (61.9%) was the most common site of metastasis followed by the bone, bone marrow, and brain."
    explanation: >-
      Supports the OCCASIONAL frequency band (5-29%) for metastatic disease at presentation — 28.8%
      of this 73-patient cohort presented with metastases — and the stated pattern of spread to lung,
      bone, and bone marrow. This is the frequency evidence; the survival items below support the
      separate prognostic claim, not the frequency.
  - reference: PMID:36669140
    reference_title: "Randomized Phase III Trial of Ganitumab With Interval-Compressed Chemotherapy for Patients With Newly Diagnosed Metastatic Ewing Sarcoma: A Report From the Children's Oncology Group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The 3-year EFS estimates were 37.4% (95% CI, 29.3 to 45.5) for the standard arm and 39.1% (95% CI, 31.3 to 46.7) for the experimental arm (stratified EFS-event hazard ratio for experimental arm 1.00; 95% CI, 0.76 to 1.33; 1-sided, P = .50)."
    explanation: Provides precise 3-year EFS data from the COG AEWS1221 phase III trial for metastatic Ewing sarcoma.
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Although only 25% of patients have obvious metastases at diagnosis
    explanation: >-
      The contemporary guideline supports the approximate presentation frequency.
- category: Musculoskeletal
  name: Pathologic Fracture
  description: >-
    Fractures can complicate osseous Ewing sarcoma at presentation or during and after treatment.
    A historical long-bone cohort reported fractures in 14/93 patients across the disease course,
    including many after radiation; this is not a disease-wide presentation frequency.
  phenotype_term:
    preferred_term: Pathologic fracture
    term:
      id: HP:0002756
      label: Pathologic fracture
  evidence:
  - reference: PMID:11902298
    reference_title: Fractures in pediatric Ewing sarcoma.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Fracture occurred in 14 (15%) of 93 patients with long-bone ESFT, most commonly in the femur.
    explanation: >-
      Retrospective long-bone cohort supports the complication, with restricted anatomy and historical
      treatment.
  - reference: PMID:11902298
    reference_title: Fractures in pediatric Ewing sarcoma.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Nine (64%) of the 14 fractures occurred after the start of radiotherapy, and three of these were associated with either local recurrence or second malignancy.
    explanation: >-
      Distinguishes disease-course fractures from presentation and treatment-associated fractures.
- category: Hematologic
  name: Anemia
  description: >-
    Anemia can accompany Ewing sarcoma but is nonspecific and must be distinguished from treatment
    toxicity and other causes. Marrow involvement is one possible context rather than a demonstrated
    cause in every patient.
  phenotype_term:
    preferred_term: Anemia
    term:
      id: HP:0001903
      label: Anemia
  evidence:
  - reference: PMID:25691401
    reference_title: "Diagnosis and treatment of Ewing sarcoma of the bone: a review article."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Anemia and leukocytosis are often observed in ES
    explanation: >-
      Clinical review supports the manifestation without a precise frequency.
biochemical:
- name: EWS-FLI1 Fusion Detection
  notes: >-
    Molecular demonstration of a compatible FET-ETS fusion confirms the integrated diagnosis. RT-PCR
    or RNA-based sequencing can identify the fusion partner. EWSR1 break-apart FISH alone is insufficiently
    specific and can miss some rearrangements; a negative or isolated positive result must be interpreted
    with morphology and immunophenotype.
  evidence:
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Genetic confirmation is required for ES diagnosis.
    explanation: >-
      Defines the molecular-confirmation requirement.
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: All cases of ES harbor a FET-ETS fusion.
    explanation: >-
      Includes rare FUS-containing fusions and distinguishes other round-cell sarcomas.
- name: CD99 and NKX2.2 Immunoreactivity
  evidence:
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Immunohistochemically, neoplastic cells show a membranous pattern of intense and diffuse CD99 expression
    explanation: >-
      The guideline identifies typical CD99 staining.
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: However, it is important to note that CD99 and NKX2.2 are not entirely specific for ES
    explanation: >-
      Explicit specificity limitation.
  notes: >-
    Diffuse membranous CD99 and nuclear NKX2.2 support Ewing sarcoma in the appropriate morphologic
    context. Both are imperfectly specific; neither replaces fusion characterization.
genetic:
- name: EWS-FLI1 Fusion
  association: Somatic Fusion Oncogene
  notes: >-
    EWSR1::FLI1 accounts for approximately 85% of cases; EWSR1::ERG and rare other FET-ETS fusions
    account for the remainder. Rare FUS-containing fusions mean that EWS-ETS is not an exhaustive
    molecular definition. These are acquired somatic drivers, not a Mendelian inheritance pattern.
  evidence:
  - reference: PMID:17250957
    reference_title: "The Biology of Ewing sarcoma."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "It is associated in 85% of cases with the t(11;22)(q24:q12) chromosomal translocation that generates fusion of the 5' segment of the EWS gene with the 3' segment of the ETS family gene FLI-1."
    explanation: Directly confirms the 85% frequency of the t(11;22) translocation creating EWS-FLI1.
- name: STAG2
  association: Somatic Tumor Suppressor Mutation
  variant_origin: SOMATIC
  frequency: 17%
  gene_term:
    preferred_term: STAG2
    term:
      id: hgnc:11355
      label: STAG2
  notes: >-
    STAG2 loss-of-function mutations and protein loss are overlapping but distinct secondary alterations.
    Mutation frequency was 17% in one whole-genome cohort; localized COG tumors showed protein loss
    in 29/108 by IHC. STAG2/TP53 co-mutation was associated with poor outcome. Mutual exclusivity
    with CDKN2A deletion was a cohort observation, not a biological impossibility of co-alteration.
    The two rates are not in conflict: a separate genomic study reports STAG2 inactivation occurring
    by rearrangement and by likely nongenetic routes as well as by point mutation, so a sequencing
    frequency is expected to sit below a protein-level rate and ascertaining a STAG2-defined
    subgroup by sequencing alone will miss cases.
  evidence:
  - reference: PMID:25223734
    reference_title: "Genomic landscape of Ewing sarcoma defines an aggressive subtype with co-association of STAG2 and TP53 mutations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Apart from whole chromosome arm copy-number changes, the most common somatic mutations were detected in STAG2 (17%), CDKN2A (12%), TP53 (7%), EZH2, BCOR, and ZMYM3 (2.7% each)."
    explanation: Establishes STAG2 as one of the most common recurrent somatic alterations in Ewing sarcoma.
  - reference: PMID:36221002
    reference_title: "Adverse prognostic impact of the loss of STAG2 protein expression in patients with newly diagnosed localised Ewing sarcoma: A report from the Children's Oncology Group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among patients with localised disease, 5-year event-free survival was 54% (95% CI 34-70%) and 75% (95% CI 63-84%) for patients with STAG2 loss vs. expression (P = 0.0034)."
    explanation: Supports the adverse clinical association of STAG2 protein loss in localized Ewing sarcoma.
  - reference: PMID:25186949
    reference_title: "The genomic landscape of pediatric Ewing sarcoma."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "occurs by point mutation, rearrangement, and likely nongenetic mechanisms; and is associated with disease dissemination"
    explanation: >-
      Establishes that STAG2 inactivation is not exclusively mutational, which is what reconciles
      the sequencing-based frequency recorded here with the higher immunohistochemical protein-loss
      rate recorded beside it.
- name: TP53
  association: Somatic Tumor Suppressor Mutation
  variant_origin: SOMATIC
  frequency: 7%
  gene_term:
    preferred_term: TP53
    term:
      id: hgnc:11998
      label: TP53
  notes: >-
    TP53 is recurrently mutated in a minority of Ewing sarcomas and co-occurs with STAG2 mutation
    in an aggressive secondary-genetic subset.
  evidence:
  - reference: PMID:25223734
    reference_title: "Genomic landscape of Ewing sarcoma defines an aggressive subtype with co-association of STAG2 and TP53 mutations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In an expanded cohort of 299 patients with clinical data, we discovered that STAG2 and TP53 mutations are often concurrent and are associated with poor outcome."
    explanation: Supports TP53 mutation as part of the high-risk STAG2/TP53 co-altered Ewing sarcoma subset.
- name: CDKN2A
  association: Somatic Tumor Suppressor Deletion
  variant_origin: SOMATIC
  frequency: 12%
  gene_term:
    preferred_term: CDKN2A
    term:
      id: hgnc:1787
      label: CDKN2A
  notes: >-
    CDKN2A deletion is a recurrent secondary alteration. Its reported mutual exclusivity with STAG2
    mutation concerns copy-number loss in particular cohorts; absence of CDKN2A point mutations in
    an unarchived portal analysis does not independently verify that relationship.
  evidence:
  - reference: PMID:25223734
    reference_title: "Genomic landscape of Ewing sarcoma defines an aggressive subtype with co-association of STAG2 and TP53 mutations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Strikingly, STAG2 mutations and CDKN2A deletions were mutually exclusive, as confirmed in Ewing sarcoma cell lines."
    explanation: Supports CDKN2A deletion as a recurrent secondary alteration distinct from STAG2-mutant Ewing sarcoma.
treatments:
- name: Neoadjuvant Chemotherapy
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    Interval-compressed vincristine, doxorubicin and cyclophosphamide alternating with ifosfamide
    and etoposide (VDC/IE), with growth-factor support and hematologic recovery criteria, is a standard
    systemic backbone. Randomized data support two-week over three-week scheduling in localized disease.
    Treatment is delivered before and after surgery and/or radiation.
  treatment_term:
    preferred_term: Neoadjuvant Chemotherapy
    term:
      id: NCIT:C213450
      label: Neoadjuvant Chemotherapy
    therapeutic_agent:
    - preferred_term: vincristine
      term:
        id: CHEBI:28445
        label: vincristine
    - preferred_term: doxorubicin
      term:
        id: CHEBI:28748
        label: doxorubicin
    - preferred_term: cyclophosphamide
      term:
        id: CHEBI:4027
        label: cyclophosphamide
    - preferred_term: ifosfamide
      term:
        id: CHEBI:5864
        label: ifosfamide
    - preferred_term: etoposide
      term:
        id: CHEBI:4911
        label: etoposide
  evidence:
  - reference: PMID:23091096
    reference_title: "Randomized controlled trial of interval-compressed chemotherapy for the treatment of localized Ewing sarcoma: a report from the Children's Oncology Group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: For localized Ewing sarcoma, chemotherapy administered every 2 weeks is more effective than chemotherapy administered every 3 weeks, with no increase in toxicity.
    explanation: >-
      The randomized COG study supports interval compression; the conclusion applies to its localized-disease
      population.
  - reference: PMID:36522207
    reference_title: "Comparison of two chemotherapy regimens in patients with newly diagnosed Ewing sarcoma (EE2012): an open-label, randomised, phase 3 trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Dose-intensive chemotherapy with vincristine, doxorubicin, cyclophosphamide, ifosfamide, and etoposide is more effective, less toxic, and shorter in duration
    explanation: >-
      EE2012 randomized evidence supports the VDC/IE approach over VIDE induction. The protocol also
      admitted Ewing-like sarcomas, a scope consideration when applying the result to modern molecular
      entities.
- name: Surgical Resection
  description: >-
    Wide surgical resection with negative margins is preferred when feasible without excessive morbidity.
    Reconstruction may be needed for limb salvage.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: Definitive Surgical Resection
    term:
      id: NCIT:C154430
      label: Definitive Surgical Resection
  evidence:
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: surgery is the treatment of choice if tumor resection is possible with negative margins, without significant morbidity, and with a reasonable functional outcome.
    explanation: >-
      Contemporary guideline supports margin-negative resection when feasible; this avoids causal
      superiority claims from a confounded observational treatment comparison.
- name: Radiation Therapy
  description: >-
    Definitive radiation is used for unresectable tumors or when surgery would cause significant
    morbidity. Also used post-operatively for close or positive margins.
  therapeutic_modality: RADIOTHERAPY
  treatment_term:
    preferred_term: Radiation Therapy
    term:
      id: NCIT:C15313
      label: Radiation Therapy
  evidence:
  - reference: PMID:33818887
    reference_title: "Ewing sarcoma."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Standard treatment involves multiagent induction chemotherapy followed by local treatment with surgery, definitive radiation, or a combination of surgery and radiation followed by additional chemotherapy and consolidation local treatment to metastatic sites."
    explanation: Confirms the role of definitive radiation as a local treatment option in Ewing sarcoma management.
- name: Adjuvant Chemotherapy
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    Systemic chemotherapy continues after local control to treat occult disseminated disease. Duration
    and consolidation depend on protocol and risk group; a fixed 9-12-month duration is not applicable
    to all modern interval-compressed regimens.
  treatment_term:
    preferred_term: chemotherapy
    term:
      id: NCIT:C15632
      label: Chemotherapy
  evidence:
  - reference: PMID:33818887
    reference_title: "Ewing sarcoma."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Standard treatment involves multiagent induction chemotherapy followed by local treatment with surgery, definitive radiation, or a combination of surgery and radiation followed by additional chemotherapy and consolidation local treatment to metastatic sites."
    explanation: The review describes continuation of systemic chemotherapy after local treatment.
- name: PARP Inhibitor Combination Therapy
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    PARP-inhibitor combinations remain investigational in recurrent/refractory Ewing sarcoma. Talazoparib
    plus temozolomide produced no objective responses in ten phase-2 Ewing patients. A later pediatric
    olaparib-irinotecan phase-I/II study reported two Ewing responses, with a 6.3% response rate
    in its evaluable Ewing cohort. These limited signals do not establish routine efficacy or a validated
    HR-deficiency biomarker.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: talazoparib
      term:
        id: CHEBI:231344
        label: talazoparib
      description: Partnered with temozolomide in ADVL1411; not a four-drug regimen.
    - preferred_term: temozolomide
      term:
        id: CHEBI:72564
        label: temozolomide
      description: Cytotoxic partner of talazoparib in ADVL1411.
    - preferred_term: olaparib
      term:
        id: CHEBI:83766
        label: olaparib
      description: Partnered with irinotecan in the separate AcSe-ESMART arm D regimen.
    - preferred_term: irinotecan
      term:
        id: CHEBI:80630
        label: irinotecan
      description: Cytotoxic partner of olaparib in AcSe-ESMART arm D.
  target_mechanisms:
  - target: PARP1-Supported Fusion Transcription
    treatment_effect: INHIBITS
    description: >-
      PARP inhibition interferes with PARP-dependent transcription and traps PARP-DNA complexes.
      Preclinical sensitivity is not equivalent to demonstrated patient benefit.
    evidence:
    - reference: PMID:26505995
      reference_title: "Combinations of PARP Inhibitors with Temozolomide Drive PARP1 Trapping and Apoptosis in Ewing's Sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Here, we show that PARP inhibitor sensitivity in Ewing's sarcoma cells is not through an apparent defect in DNA repair by HR, but through hypersensitivity to trapped PARP1-DNA complexes.
      explanation: >-
        Supports PARP trapping as a cellular mechanism.
  evidence:
  - reference: PMID:31724813
    reference_title: "Phase 1/2 trial of talazoparib in combination with temozolomide in children and adolescents with refractory/recurrent solid tumors including Ewing sarcoma: A Children's Oncology Group Phase 1 Consortium study (ADVL1411)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In phase 2, 0 of 10 EWS subjects experienced an objective response; two experienced prolonged SD."
    explanation: >-
      Clinical evidence supports feasibility but only partial therapeutic support because objective
      responses were not observed in the phase 2 Ewing cohort.
  - reference: PMID:41591981
    reference_title: "Phase I/II Study of the PARP Inhibitor Olaparib and Irinotecan in Children and Young Adults with Recurrent/Refractory Malignancies: Arm D of the AcSé-ESMART Trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Two patients with Ewing sarcoma experienced a complete and a partial response for 10 and 42 cycles, respectively.
    explanation: >-
      Limited activity in a later phase-I/II combination trial; this does not establish general efficacy
      or attribute the effect uniquely to PARP inhibition.
- name: LSD1 Inhibitor Therapy
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    Seclidemstat (SP-2577) is an investigational LSD1-associated transcriptional modulator studied
    in fusion-positive sarcoma cells and trials. Laboratory activity links to fusion-dependent
    transcription, but clinical efficacy in Ewing sarcoma is unproven and preclinical xenograft
    activity has been limited.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: seclidemstat
      term:
        id: NCIT:C154328
        label: Seclidemstat
  target_mechanisms:
  - target: NuRD-LSD1 Transcriptional Repression
    treatment_effect: MODULATES
    description: >-
      Seclidemstat is intended to modulate LSD1-linked transcriptional and chromatin programs
      downstream of EWS-FLI1 and related FET fusion proteins.
    evidence:
    - reference: PMID:40852926
      reference_title: "Seclidemstat (SP-2577) Induces Transcriptomic Reprogramming and Cytotoxicity in Multiple Fusion-Positive Sarcomas."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Seclidemstat recapitulated much of SP-2509 transcriptional activity in Ewing sarcoma."
      explanation: Supports seclidemstat modulation of the Ewing sarcoma transcriptional program linked to the LSD1 pathograph arm.
  evidence:
  - reference: PMID:40852926
    reference_title: "Seclidemstat (SP-2577) Induces Transcriptomic Reprogramming and Cytotoxicity in Multiple Fusion-Positive Sarcomas."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Seclidemstat recapitulated much of SP-2509 transcriptional activity in Ewing sarcoma."
    explanation: >-
      This is an in-vitro pharmacology result. A paper mentioning a trial does not verify its
      current registry status or clinical efficacy.
  - reference: PMID:34453478
    reference_title: "In vivo evaluation of the lysine-specific demethylase (KDM1A/LSD1) inhibitor SP-2577 (Seclidemstat) against pediatric sarcoma preclinical models: A report from the Pediatric Preclinical Testing Consortium (PPTC)."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "SP-2577 (100 mg/kg/day × 28 days) statistically significantly (p < .05) inhibited growth of three of eight Ewing sarcoma (EwS), four of five rhabdomyosarcoma (RMS), and four of six osteosarcoma (OS) xenografts."
    explanation: >-
      Supports in vivo preclinical activity in a subset of Ewing xenografts, but only partial
      support because the same abstract reports limited activity overall.
  notes: >-
    A July 2024 sponsor SEC filing states that the Ewing seclidemstat phase I/II trial was
    terminated to conserve cash. Later preclinical papers mentioning clinical trials do not
    establish continued recruitment or efficacy. Source:
    https://www.sec.gov/Archives/edgar/data/1615219/000161521924000071/flks-20240630.htm
- name: USP1 Inhibitor Therapy
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    USP1 inhibition is a preclinical targeted strategy aimed at the EWS-FLI1 induced USP1-survivin
    survival buffer that helps Ewing sarcoma cells tolerate endogenous replication stress and standard
    chemotherapy exposure.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: USP1 inhibitor
      description: >-
        Local NCIT/CHEBI search did not identify a USP1-specific inhibitor class; this uses the broader
        NCIT enzyme inhibitor class while preserving USP1 specificity in preferred_term.
      term:
        id: NCIT:C471
        label: Enzyme Inhibitor
  target_mechanisms:
  - target: USP1-Survivin Stress Buffering
    treatment_effect: INHIBITS
    description: >-
      USP1 inhibition blocks a survival adaptation within the replication-stress node by destabilizing
      the USP1-survivin axis and sensitizing cells to DNA damaging chemotherapy.
    evidence:
    - reference: PMID:37478161
      reference_title: "USP1 Expression Driven by EWS::FLI1 Transcription Factor Stabilizes Survivin and Mitigates Replication Stress in Ewing Sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Notably, USP1 inhibition sensitizes cells to doxorubicin and etoposide treatment."
      explanation: >-
        Supports targeting the USP1-dependent replication-stress survival buffer in Ewing sarcoma
        cells.
  evidence:
  - reference: PMID:37478161
    reference_title: "USP1 Expression Driven by EWS::FLI1 Transcription Factor Stabilizes Survivin and Mitigates Replication Stress in Ewing Sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "USP1 knockdown or inhibition arrests EWS cell growth and induces cell death by apoptosis."
    explanation: Supports USP1 inhibition as a preclinical targeted treatment concept in Ewing sarcoma.
- name: Dual PARP-HDAC Inhibition
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    The bifunctional compound kt-3283 has preclinical activity in Ewing cells and spheroids. It inhibits
    PARP1/2 and HDAC enzymes; these observations do not establish direct CHD4 inhibition or clinical
    efficacy.
  evidence:
  - reference: PMID:37279093
    reference_title: A Bifunctional PARP-HDAC Inhibitor with Activity in Ewing Sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Here, we report the concept and characterization of a novel bifunctional PARPi (kt-3283) with dual activity toward PARP1/2 and HDAC enzymes in Ewing sarcoma cells.
    explanation: >-
      Preclinical dual-target pharmacology, distinct from clinical talazoparib/temozolomide.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: kt-3283
      description: NCIT and CHEBI searches for kt-3283, kt3283 and KT 3283 found no compound-specific term. The broader PARP-inhibitor class describes one experimentally measured activity of this single bifunctional compound; HDAC inhibition remains explicit in the treatment description. This is not talazoparib, olaparib or a combination of two agents.
      term:
        id: NCIT:C62554
        label: Poly (ADP-Ribose) Polymerase Inhibitor
  target_mechanisms:
  - target: PARP1-Supported Fusion Transcription
    treatment_effect: INHIBITS
    description: >-
      The compound inhibits PARP1/2 as one of its two measured enzymatic targets.
    evidence:
    - reference: PMID:37279093
      reference_title: A Bifunctional PARP-HDAC Inhibitor with Activity in Ewing Sarcoma.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Here, we report the concept and characterization of a novel bifunctional PARPi (kt-3283) with dual activity toward PARP1/2 and HDAC enzymes in Ewing sarcoma cells.
      explanation: >-
        Preclinical dual-target pharmacology, distinct from clinical talazoparib/temozolomide.
- name: Cabozantinib in Advanced Disease
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    Cabozantinib, a MET/VEGFR2 inhibitor, showed activity in the single-arm CABONE phase-II trial
    in advanced Ewing sarcoma: 10/39 efficacy-evaluable patients had partial responses by six months.
    This is a salvage research option with toxicity and limited comparative evidence, not an established
    replacement for frontline multimodal therapy.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: cabozantinib
      term:
        id: CHEBI:72317
        label: cabozantinib
  evidence:
  - reference: PMID:32078813
    reference_title: "Cabozantinib in patients with advanced Ewing sarcoma or osteosarcoma (CABONE): a multicentre, single-arm, phase 2 trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: In patients with Ewing sarcoma, ten (26%; 95% CI 13-42) of 39 patients had an objective response (all partial responses) by 6 months
    explanation: >-
      Single-arm phase-II activity among efficacy-evaluable advanced Ewing patients, not proof of
      survival benefit or frontline efficacy.
- name: High-Dose Ifosfamide for Recurrent or Refractory Disease
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    The rEECur randomized salvage study provides comparative evidence favoring high-dose
    ifosfamide over topotecan-cyclophosphamide after earlier gemcitabine-docetaxel and
    irinotecan-temozolomide arms closed. The 2022 phase III conference report compared 73 patients
    per arm: median event-free survival was 5.7 versus 3.7 months and overall survival 16.8 versus
    10.4 months for ifosfamide versus topotecan-cyclophosphamide. Renal toxicity and
    encephalopathy constrain selection and monitoring; this does not establish universal
    suitability or cure.
  treatment_term:
    preferred_term: chemotherapy
    term:
      id: NCIT:C15632
      label: Chemotherapy
    therapeutic_agent:
    - preferred_term: ifosfamide
      term:
        id: CHEBI:5864
        label: ifosfamide
  evidence:
  - reference: DOI:10.1200/JCO.2022.40.17_suppl.LBA2
    reference_title: "Phase III assessment of topotecan and cyclophosphamide and high-dose ifosfamide in rEECur: An international randomized controlled trial of chemotherapy for the treatment of recurrent and primary refractory Ewing sarcoma (RR-ES)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: For the phase III comparison between TC and IFOS (both, 73 patients), median EFS was 3.7 months (95% CI, 2.1-6.2) for TC and 5.7 months (95% CI, 3.8-7.0) for IFOS. Median OS was 10.4 months (95% CI, 7.5-15.5) for TC and 16.8 months (95% CI, 11.1-25.8) for IFOS.
    explanation: >-
      Primary randomized conference abstract reports event-free and overall survival in the
      contemporaneous phase III comparison; EFS must not be relabeled as PFS.
  - reference: DOI:10.1200/JCO.2022.40.17_suppl.LBA2
    reference_title: "Phase III assessment of topotecan and cyclophosphamide and high-dose ifosfamide in rEECur: An international randomized controlled trial of chemotherapy for the treatment of recurrent and primary refractory Ewing sarcoma (RR-ES)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: 'The main grade 3/4 adverse events (% patients with an event) for TC (left-hand values) compared with IFOS were: febrile neutropenia (26% vs. 25%), infections (8% vs. 14%), vomiting (1% vs. 1%), nausea (0% vs. 3%), diarrhea (1% vs. 1%), encephalopathy (0% vs. 7%), and renal toxicity (0% vs. 8%).'
    explanation: >-
      The comparative adverse-event data are relevant to salvage regimen selection.
  notes: >-
    The trial-team November 2025 update reports that carboplatin-etoposide closed in August 2024
    and the continuing comparison is ifosfamide with or without lenvatinib; the older guideline
    statement that carboplatin-etoposide remained under comparison is superseded. Source:
    https://www.ucl.ac.uk/medical-sciences/divisions/cancer/centres-and-networks/euro-ewing-consortium/clinical-trials/reecur
experimental_models:
- name: Ewing sarcoma tumor organoid model systems
  description: >-
    Tumor organoids are part of the current Ewing sarcoma preclinical model landscape and provide
    a non-animal 3D system for therapy evaluation and mechanism-focused modeling alongside cell lines
    and xenografts.
  experimental_model_type: ORGANOID
  namo_type: namo:Organoid
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  conditions:
  - Ewing sarcoma
  - tumor organoid preclinical modeling
  cell_source: Ewing sarcoma tumor-derived cells
  culture_system: Three-dimensional tumor organoid culture
  publication: PMID:40911901
  modeled_mechanisms:
  - target: EWS-FLI1 Fusion Oncogene
    description: Models fusion-positive tumor biology in a 3D non-animal context.
  - target: Tumor Cell Proliferation and Survival
    description: Enables preclinical testing of tumor growth and survival responses.
  evidence:
  - reference: PMID:40911901
    reference_title: "Advancing Preclinical Biology for Ewing Sarcoma: An International Effort."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Through an international collaborative effort between the Children's Oncology Group Bone Tumor Committee and the Euro Ewing Consortium, we review the current landscape of preclinical modeling used in Ewing sarcoma research encompassing both in vitro (cell lines and tumor organoids) and in vivo (mouse and nonmammalian xenografts) model systems."
    explanation: Supports tumor organoids as part of the Ewing sarcoma preclinical modeling landscape.
- name: Patient-derived Ewing sarcoma culture panel
  description: >-
    Patient-derived Ewing sarcoma cultures provide a primary-cell in vitro non-animal model for studying
    EWSR1 fusion status, proliferation, migration, and treatment response in models that differ transcriptionally
    from long-established cell lines.
  experimental_model_type: PRIMARY_CELL_CULTURE
  namo_type: namo:TwoDCellCulture
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  conditions:
  - Ewing sarcoma
  - patient-derived ES cultures
  - preclinical drug response testing
  cell_source: Patient-derived Ewing sarcoma tumor cultures
  culture_system: Patient-derived in vitro culture
  publication: PMID:41681984
  modeled_mechanisms:
  - target: EWS-FLI1 Fusion Oncogene
    description: Models EWSR1 fusion-positive tumor state in patient-derived cultures.
  - target: Tumor Cell Proliferation and Survival
    description: Assays patient-derived proliferation and therapy-response phenotypes.
  findings:
  - statement: Patient-derived Ewing cultures retain EWSR1 fusion DNA.
    evidence:
    - reference: PMID:41681984
      reference_title: "Characterisation of Bespoke Patient-Derived In Vitro Models of Ewing Sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Results: All PDES contain EWSR1 fusion DNA, consistent with a diagnosis of ES."
      explanation: Supports PDES as patient-derived, fusion-positive Ewing sarcoma models.
  evidence:
  - reference: PMID:41681984
    reference_title: "Characterisation of Bespoke Patient-Derived In Vitro Models of Ewing Sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "To expedite this process, we have established and characterised patient-derived ES cultures (PDES) in vitro."
    explanation: Supports this as a patient-derived in vitro Ewing sarcoma model system.
- name: Flow-perfusion Ewing sarcoma 3D scaffold coculture
  description: >-
    Flow-perfusion 3D scaffold cocultures combine Ewing sarcoma cells with mesenchymal stromal cells
    under biomechanical stimulation, enabling controlled testing of tumor-stroma signaling, IGF-1R/STAT3
    biology, and drug-resistance mechanisms that are absent from standard monolayer systems.
  experimental_model_type: CO_CULTURE
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_types:
  - preferred_term: mesenchymal stem cell
    term:
      id: CL:0000134
      label: mesenchymal stem cell
  conditions:
  - Ewing sarcoma
  - tumor-stroma coculture
  - flow perfusion
  cell_source: Ewing sarcoma cells cocultured with mesenchymal stem cells
  culture_system: 3D scaffold coculture in a flow perfusion bioreactor
  publication: PMID:27923328
  modeled_mechanisms:
  - target: Tumor-Stroma IL-6/STAT3 Signaling
    description: >-
      Assays IL-6/STAT3 tumor-stroma signaling and drug response under biophysical stimulation; it
      does not test developmental IGF-1/YAP1 initiation.
  - target: Tumor Cell Proliferation and Survival
    description: Models stromal support of growth and drug-resistance phenotypes.
  evidence:
  - reference: PMID:27923328
    reference_title: "Modeling Stroma-Induced Drug Resistance in a Tissue-Engineered Tumor Model of Ewing Sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Here, we demonstrate that these same biophysical cues-modeled by coculturing ES cells and mesenchymal stem cells (MSCs) in 3D scaffolds within a flow perfusion bioreactor-activate interleukin-6 and transcription factor Stat3."
    explanation: Supports this as a 3D tumor-stroma coculture model for Ewing sarcoma.
  - reference: PMID:26240353
    reference_title: "Flow perfusion effects on three-dimensional culture and drug sensitivity of Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "To address this issue, we cultured Ewing sarcoma (ES) cells on electrospun poly(ε-caprolactone) 3D scaffolds within a flow perfusion bioreactor."
    explanation: Supports the flow-perfusion scaffold format for Ewing sarcoma drug-sensitivity modeling.
- name: Human embryonic mesenchymal stem cell EWS-FLI1 transformation model
  description: >-
    Early human embryonic mesenchymal stem cells transduced with EWS-FLI1 acquire an Ewing-like
    transcriptome. Tumor formation was tested separately in immunodeficient xenograft hosts. This
    engineered permissiveness differs from later MSC states tested in the study; it does not
    uniquely identify the human lineage of origin.
  experimental_model_type: PRIMARY_CELL_CULTURE
  namo_type: namo:TwoDCellCulture
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_types:
  - preferred_term: mesenchymal stem cell
    term:
      id: CL:0000134
      label: mesenchymal stem cell
  conditions:
  - Ewing sarcoma
  - EWS-FLI1 transformation
  - embryonic developmental context
  cell_source: Human embryonic mesenchymal stem cells (heMSCs) transduced with EWS::FLI1 lentivirus
  culture_system: Primary embryonic MSC culture with lentiviral oncogene transduction and xenograft validation
  publication: PMID:41136396
  modeled_mechanisms:
  - target: EWS-FLI1 Fusion Oncogene
    description: >-
      Models EWS-FLI1 oncogene expression in an embryonic human mesenchymal developmental context,
      with xenograft tumor formation demonstrating transformation capacity.
  - target: Permissive Progenitor Cell State
    description: >-
      Demonstrates that only undifferentiated, early heMSCs (not adult MSCs or pediatric MSCs) fully
      support EWS-FLI1 transformation, linking progenitor developmental state to oncogenic
      permissiveness.
  - target: Context-Dependent BRCA1 Repair Impairment
    description: >-
      Measures altered BRCA1 expression, localization and damage-response phosphorylation alongside
      defective DNA repair in comet assays after EWS-FLI1 expression.
    relationship: MEASURES
    limitations: >-
      The study does not directly measure R-loop accumulation or isolate homologous-recombination
      repair with an HR-specific functional assay; those mechanisms cannot be inferred solely from
      BRCA1 and total DNA-damage readouts.
  evidence:
  - reference: PMID:41136396
    reference_title: "EWS::FLI1 expression in human embryonic mesenchymal stem cells leads to transcriptional reprograming, defective DNA damage repair and Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "In summary, we show that EWS::FLI1 enforces an aberrant transcriptome and solely is able to endow transforming capacity when expressed in undifferentiated, early heMSCs."
    explanation: >-
      The conclusion compares early embryonic MSCs with other tested MSC states. It does not exclude
      every other progenitor type or eliminate the animal component of tumorigenicity validation.
- name: BARD1-variant PSaRC318 and BARD1-depleted Ewing cells
  experimental_model_type: CELL_LINE
  namo_type: namo:TwoDCellCulture
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_source: Patient-derived PSaRC318 Ewing sarcoma cells and established Ewing cell lines
  culture_system: Cell culture with BARD1 or GBP1 siRNA, PARP inhibitors and radiation
  publication: PMID:36187937
  description: >-
    PSaRC318 derives from one patient with a germline pathogenic BARD1 variant. BARD1 depletion in
    other Ewing lines and GBP1 knockdown test the cellular contribution to damage sensitivity.
    These interventions do not establish treatment benefit in patients.
  modeled_mechanisms:
  - target: BARD1-Loss and GBP1-Associated DNA-Damage Sensitivity
    description: Tests BARD1 depletion and the contribution of GBP1 to PARP-inhibitor or radiation-associated apoptosis.
    relationship: PERTURBS
    limitations: Patient-derived and knockdown culture findings do not establish clinical predictive validity.
  evidence:
  - reference: PMID:36187937
    reference_title: BRCA1-associated RING domain-1 (BARD1) loss and GBP1 expression enhance sensitivity to DNA damage in Ewing sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: We demonstrate that PSaRC318 cells, a novel patient-derived cell line harboring a pathogenic BARD1 variant, are sensitive to PARP inhibition and by testing the effect of BARD1 depletion in additional Ewing sarcoma cell lines, we confirm that BARD1 loss enhances cell sensitivity to PARP inhibition plus radiation.
    explanation: >-
      Patient-derived and BARD1-depleted cell models support an experimental modifier, not a
      validated patient biomarker or a ten-percent BARD1 frequency.
  - reference: PMID:36187937
    reference_title: BRCA1-associated RING domain-1 (BARD1) loss and GBP1 expression enhance sensitivity to DNA damage in Ewing sarcoma.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Here, we demonstrate that GBP1 contributes to the enhanced sensitivity of BARD1 deficient Ewing cells to DNA damage.
    explanation: >-
      GBP1 knockdown reduced radiation- and niraparib-associated apoptosis in PSaRC318 cells; GBP1
      expression is not specific to BARD1 loss.
discussions:
- discussion_id: gap_ewing_cell_of_origin_context
  prompt: >-
    Which human progenitor state is truly permissive for EWS-FLI1 transformation, and what chromatin
    or differentiation-state features distinguish transforming early mesenchymal or neural crest-like
    cells from non-transforming MSC states?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Permissive Progenitor Cell State
  - pathophysiology#IGF-1/YAP1 Developmental Cooperation
  - pathophysiology#GGAA Microsatellite Germline Susceptibility Architecture
  - pathophysiology#EWS-FLI1 Fusion Oncogene
  - pathophysiology#GGAA Microsatellite Enhancer Reprogramming
  rationale: >-
    Neural crest-derived cells, bone marrow-derived MSCs, pediatric MSCs, adult MSCs, and 2025 embryonic
    MSC models support overlapping but not identical origin hypotheses. The unresolved mechanism
    is not simply whether EWS-FLI1 can alter transcription, but which developmental chromatin state
    lets GGAA enhancer rewiring become transforming rather than toxic, senescent, or differentiation-inducing.
    IGF-1/YAP1 signaling and germline GGAA repeat architecture now provide concrete cooperating mechanisms,
    but neither yet defines the full permissive human progenitor state. The fusion can pioneer previously
    closed GGAA sites, so pre-existing accessibility at all repeats

    is not a necessary criterion for permissiveness. Adult diagnosis does not by itself date the
    initiating event. YAP1 opposition to fusion transcription is not equivalent to tumor suppression
    in established Ewing sarcoma.
  proposed_experiments:
  - experiment_id: exp_ewing_isogenic_developmental_context_panel
    name: Isogenic developmental-context EWS-FLI1 induction panel
    description: >-
      Build an inducible or safe-harbor knock-in EWS-FLI1 panel across hPSC-derived migratory neural
      crest cells, early mesenchymal progenitors, osteochondral progenitors, pediatric MSCs, and
      adult MSCs. Measure the same fusion dose and timing across lineages, then compare enhancer
      activation, differentiation blockade, DNA-damage state, senescence, and xenograft or organoid
      tumorigenicity.
    experiment_type:
      preferred_term: isogenic stem-cell transformation assay
    model_systems:
    - name: hPSC-derived neural crest and early mesenchymal progenitor panel
      description: >-
        Genome-engineered human pluripotent stem cell derivatives with matched EWS-FLI1 induction
        across candidate Ewing sarcoma cells of origin.
      experimental_model_type: IPSC_DERIVED_MODEL
      organism:
        preferred_term: human
        term:
          id: NCBITaxon:9606
          label: Homo sapiens
      cell_types:
      - preferred_term: migratory neural crest cell
        term:
          id: CL:0000333
          label: migratory neural crest cell
      - preferred_term: early mesenchymal stem cell
        term:
          id: CL:0000134
          label: mesenchymal stem cell
      publication: PMID:41136396
      modeled_mechanisms:
      - target: Permissive Progenitor Cell State
        description: Tests whether early developmental context permits EWS-FLI1 transformation.
      - target: GGAA Microsatellite Enhancer Reprogramming
        description: Measures whether the same fusion activates different GGAA enhancer programs by cell state.
    perturbations:
    - name: Inducible EWS-FLI1 expression
      target: pathophysiology#EWS-FLI1 Fusion Oncogene
      description: >
        Express matched EWS-FLI1 at controlled dose and timing across candidate progenitor states.
      genes:
      - preferred_term: EWSR1
        term:
          id: hgnc:3508
          label: EWSR1
      - preferred_term: FLI1
        term:
          id: hgnc:3749
          label: FLI1
    - name: Pubertal IGF-1/YAP1 modulation
      target: pathophysiology#IGF-1/YAP1 Developmental Cooperation
      description: >
        Add pubertal-range IGF-1 exposure and YAP1/TEAD inhibition or knockout arms to determine
        whether the cooperating signal is conserved in human progenitors.
      genes:
      - preferred_term: IGF1
        term:
          id: hgnc:5464
          label: IGF1
      - preferred_term: YAP1
        term:
          id: hgnc:16262
          label: YAP1
    readouts:
    - name: GGAA enhancer activation by developmental state
      target: pathophysiology#GGAA Microsatellite Enhancer Reprogramming
      description: >
        Compare EWS-FLI1 occupancy, chromatin accessibility, and H3K27ac gain at endogenous GGAA
        microsatellites.
      biological_processes:
      - preferred_term: chromatin remodeling
        term:
          id: GO:0006338
          label: chromatin remodeling
      assays:
      - preferred_term: single-cell ATAC-seq
      - preferred_term: CUT&Tag
      - preferred_term: single-cell RNA-seq
      direction: POSITIVE
    - name: Transformation and differentiation blockade
      target: pathophysiology#Blocked Differentiation
      description: >
        Measure loss of mesenchymal/osteochondral differentiation capacity, acquisition of Ewing-like
        transcription, senescence avoidance, and tumor formation in permissive contexts.
      biological_processes:
      - preferred_term: mesenchymal cell differentiation
        term:
          id: GO:0048762
          label: mesenchymal cell differentiation
      assays:
      - preferred_term: differentiation assay
      - preferred_term: xenograft tumorigenicity assay
      direction: NEGATIVE
    controls:
    - name: Isogenic uninduced progenitor controls
      description: Same genetic background and differentiation state without EWS-FLI1 induction.
    - name: Nonpermissive adult MSC comparator
      description: Mature MSC context expected to show incomplete transformation or toxicity.
    - name: Fusion knockdown or degron rescue
      description: Acute EWS-FLI1 withdrawal after Ewing-like state acquisition.
    decision_criterion: >-
      The cell-of-origin model is prioritized when a specific progenitor state reproducibly shows
      EWS-FLI1-dependent GGAA enhancer activation, Ewing-like core regulatory circuitry, differentiation
      blockade, and tumorigenicity while closely related states fail one or more of those criteria.
      Do not require every successful enhancer to be open before fusion expression: measure both
      baseline and induced accessibility. Distinguish developmental transformation from maintenance
      and growth of established tumors.
    would_support:
    - pathophysiology#Permissive Progenitor Cell State
    - pathophysiology#IGF-1/YAP1 Developmental Cooperation
    - pathophysiology#GGAA Microsatellite Enhancer Reprogramming
    - pathophysiology#Blocked Differentiation
    would_refute:
    - pathophysiology#Permissive Progenitor Cell State
    evidence:
    - reference: PMID:41136396
      reference_title: "EWS::FLI1 expression in human embryonic mesenchymal stem cells leads to transcriptional reprograming, defective DNA damage repair and Ewing sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Here we show that EWS::FLI1 expression in human embryonic mesenchymal stem cells (heMSCs) results in the acquisition of an ES transcriptome, with the oncogene not preferentially binding to gene promoters, but to intronic and intergenic microsatellites."
      explanation: Supports the feasibility and rationale for testing early human mesenchymal contexts.
    - reference: PMID:21559395
      reference_title: "Modeling initiation of Ewing sarcoma in human neural crest cells."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Importantly, whole genome expression profiling studies revealed that the molecular signature of established ESFT is more similar to hNCSC than any other normal tissue, including MSC, indicating that maintenance or reactivation of the NCSC program is a feature of ESFT pathogenesis."
      explanation: Supports including neural crest-derived progenitors in the comparative panel.
  evidence:
  - reference: PMID:41136396
    reference_title: "EWS::FLI1 expression in human embryonic mesenchymal stem cells leads to transcriptional reprograming, defective DNA damage repair and Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Ewing sarcoma (ES) is an aggressive bone and soft tissue neoplasm characterized by EWSR::ETS rearrangements whose cellular origin remains unclear."
    explanation: Directly states the knowledge gap.
  - reference: PMID:40080499
    reference_title: "YAP1 is a key regulator of EWS::FLI1-dependent malignant transformation upon IGF-1-mediated reprogramming of bone mesenchymal stem cells."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We report that transient exposure to IGF-1 concentrations mimicking serum levels during puberty reprograms limb-derived mesenchymal cells of EWS::FLI1-mutant mice to stable transformation and tumorigenicity."
    explanation: Supports adding IGF-1/YAP1 as a concrete cooperating mechanism that still needs human validation.
  - reference: PMID:36787739
    reference_title: "Targeted long-read sequencing of the Ewing sarcoma 6p25.1 susceptibility locus identifies germline-somatic interactions with EWSR1-FLI1 binding."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified 50 microsatellite alleles at 6p25.1 and observed that EwS-affected individuals had longer alleles (>135 bp) with more GGAA repeats."
    explanation: Supports inherited GGAA architecture as part of the permissive-context gap.
- discussion_id: gap_ewing_ggaa_enhancer_grammar
  prompt: >-
    What GGAA microsatellite grammar and cofactor context make EWS-FLI1 binding oncogenic, and why
    do ETV6, BAF, and STAG2/cohesin perturbations produce different enhancer and differentiation
    outcomes?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#EWS-FLI1 Chromatin Hub Dynamics
  - pathophysiology#BAF Complex Retargeting
  - pathophysiology#GGAA Microsatellite Enhancer Reprogramming
  - pathophysiology#ETV6 GGAA Counter-Regulation
  - pathophysiology#GGAA Microsatellite Germline Susceptibility Architecture
  - pathophysiology#STAG2-Modified Enhancer State
  rationale: >-
    EWS-FLI1 binds GGAA repeats, but binding alone does not explain why some microsatellites become
    oncogenic enhancers, why germline repeat length at EGR2 and RREB1 changes susceptibility, why
    ETV6 antagonism can redirect occupancy toward differentiation, or why STAG2 loss selectively
    amplifies multimeric GGAA enhancer programs. This gap is the enhancer-grammar layer of the pathograph,
    now spanning DNA sequence, hub dosage, native ETS competition, and cohesin state.
  proposed_experiments:
  - experiment_id: exp_ewing_endogenous_ggaa_saturation_editing
    name: Endogenous GGAA enhancer grammar saturation editing
    description: >-
      Use multiplex prime/base editing or CRISPR replacement to vary repeat length, repeat purity,
      flanking ETS motifs, and local chromatin context at endogenous EWS-FLI1-bound GGAA microsatellites.
      Combine these edits with acute BAF, ETV6, and STAG2 perturbations to quantify how enhancer
      grammar and cofactor state determine transcriptional output.
    experiment_type:
      preferred_term: pooled endogenous enhancer saturation editing experiment
    model_systems:
    - name: Ewing sarcoma cell-line and early progenitor enhancer-editing panel
      description: >-
        EWS-FLI1-positive Ewing sarcoma cell lines plus permissive progenitor models with editable
        endogenous GGAA microsatellite enhancers.
      experimental_model_type: CELL_LINE
      organism:
        preferred_term: human
        term:
          id: NCBITaxon:9606
          label: Homo sapiens
      publication: PMID:41950086
      modeled_mechanisms:
      - target: GGAA Microsatellite Enhancer Reprogramming
        description: Tests enhancer sequence grammar required for de novo enhancer function.
      - target: STAG2-Modified Enhancer State
        description: Tests how STAG2 loss changes enhancer grammar dependence.
    perturbations:
    - name: GGAA microsatellite sequence editing
      target: pathophysiology#GGAA Microsatellite Enhancer Reprogramming
      description: >
        Edit endogenous EWS-FLI1-bound GGAA repeats across short, intermediate, and long repeat classes,
        including susceptibility alleles at EGR2 and RREB1.
      genes:
      - preferred_term: EGR2
        term:
          id: hgnc:3239
          label: EGR2
      - preferred_term: RREB1
        term:
          id: hgnc:10449
          label: RREB1
    - name: ETV6, STAG2, and BAF cofactor perturbation
      target: pathophysiology#BAF Complex Retargeting
      description: >
        Combine enhancer edits with degron, CRISPRi, or knockout perturbations of ETV6, STAG2, and
        BAF complex activity.
      genes:
      - preferred_term: ETV6
        term:
          id: hgnc:3495
          label: ETV6
      - preferred_term: STAG2
        term:
          id: hgnc:11355
          label: STAG2
    readouts:
    - name: Enhancer occupancy and activity
      target: pathophysiology#GGAA Microsatellite Enhancer Reprogramming
      description: >
        Quantify EWS-FLI1 occupancy, BAF recruitment, chromatin accessibility, H3K27ac, enhancer-promoter
        contact, and target-gene transcription for each edited enhancer allele.
      biological_processes:
      - preferred_term: regulation of gene expression
        term:
          id: GO:0010468
          label: regulation of gene expression
      assays:
      - preferred_term: CUT&Tag
      - preferred_term: ATAC-seq
      - preferred_term: HiChIP
      - preferred_term: single-cell RNA-seq
      direction: POSITIVE
    - name: Differentiation versus proliferation outcome
      target: pathophysiology#Core Regulatory Circuitry Activation
      description: >
        Determine whether edited enhancer states reinforce Ewing core regulatory circuitry, drive
        mesenchymal differentiation, or reduce tumor cell growth.
      biological_processes:
      - preferred_term: cell population proliferation
        term:
          id: GO:0008283
          label: cell population proliferation
      assays:
      - preferred_term: pooled growth screen
      - preferred_term: differentiation marker profiling
      direction: POSITIVE
    controls:
    - name: Synonymous non-GGAA neutral edits
      description: Editing controls matched for guide delivery and repair outcome.
    - name: EWS-FLI1 degron withdrawal
      description: Fusion-dependence control for edited enhancer activity.
    decision_criterion: >-
      A causal enhancer-grammar rule is supported when endogenous repeat edits produce predictable
      EWS-FLI1 occupancy, BAF recruitment, enhancer-promoter contact, and transcriptional changes
      that reverse with fusion withdrawal and change coherently under ETV6 or STAG2 perturbation.
    would_support:
    - pathophysiology#GGAA Microsatellite Enhancer Reprogramming
    - pathophysiology#BAF Complex Retargeting
    - pathophysiology#STAG2-Modified Enhancer State
    would_refute:
    - pathophysiology#STAG2-Modified Enhancer State
    evidence:
    - reference: PMID:36658219
      reference_title: "ETV6 dependency in Ewing sarcoma by antagonism of EWS-FLI1-mediated enhancer activation."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Using biochemical assays and epigenomics, we show that ETV6 competes with EWS-FLI1 for binding to select DNA elements enriched for short GGAA repeat sequences."
      explanation: Supports testing ETV6 as an enhancer-grammar modifier.
    - reference: PMID:41950086
      reference_title: "STAG2 loss amplifies EWS-FLI1-driven microsatellite enhancer activity promoting Ewing sarcoma aggressiveness."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "These reprogrammed sites show changes in both chromatin accessibility and H3K27ac, leading to selective amplification of EWS-FLI1 activity at multimeric microsatellite enhancers."
      explanation: Supports testing repeat-length-dependent STAG2 effects.
  evidence:
  - reference: PMID:25453903
    reference_title: "EWS-FLI1 utilizes divergent chromatin remodeling mechanisms to directly activate or repress enhancer elements in Ewing sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "At GGAA repeat elements, which lack evolutionary conservation and regulatory potential in other cell types, EWS-FLI1 multimers induce chromatin opening and create de novo enhancers that physically interact with target promoters."
    explanation: Establishes the enhancer phenomenon whose causal sequence rules remain unresolved.
  - reference: PMID:26214589
    reference_title: "Chimeric EWSR1-FLI1 regulates the Ewing sarcoma susceptibility gene EGR2 via a GGAA microsatellite."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "At rs79965208, the A risk allele connected adjacent GGAA repeats by converting an interspaced GGAT motif into a GGAA motif, thereby increasing the number of consecutive GGAA motifs and thus the EWSR1-FLI1-dependent enhancer activity of this sequence, with epigenetic characteristics of an active regulatory element."
    explanation: Supports germline repeat architecture as a testable enhancer-grammar variable.
  - reference: PMID:36787739
    reference_title: "Targeted long-read sequencing of the Ewing sarcoma 6p25.1 susceptibility locus identifies germline-somatic interactions with EWSR1-FLI1 binding."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified 50 microsatellite alleles at 6p25.1 and observed that EwS-affected individuals had longer alleles (>135 bp) with more GGAA repeats."
    explanation: Supports long-read resolution of germline GGAA alleles as part of the enhancer-grammar gap.
  - reference: PMID:40215343
    reference_title: "(GGAA)(3)-Based TF-PROTACs Enable Targeted Degradation of ETV6 to Inhibit Ewing Sarcoma Growth."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Recent studies identified ETV6 as a vulnerability in Ewing sarcoma, where it competes with EWS::FLI1 at short GGAA repeats to restrain EWS::FLI1 function."
    explanation: Supports native ETS competition as a mechanistic component of enhancer grammar.
- discussion_id: gap_ewing_chromatin_reversal_screen
  prompt: >-
    Which EWS-FLI1-dependent chromatin-accessibility states are causal tumor dependencies rather
    than passenger signatures, and can an automated high-throughput chromatin assay distinguish therapeutically
    useful chromatin reversal from nonspecific cytotoxicity?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#EWS-FLI1 Fusion Oncogene
  - pathophysiology#EWS-FLI1 Chromatin Hub Dynamics
  - pathophysiology#GGAA Microsatellite Enhancer Reprogramming
  - pathophysiology#ETV6 GGAA Counter-Regulation
  - pathophysiology#NuRD-LSD1 Transcriptional Repression
  - pathophysiology#Core Regulatory Circuitry Activation
  rationale: >-
    Ian Davis lab work showed that EWS-FLI1 retargets chromatin, creates nucleosome-depleted enhancer
    states, and can be assayed with automated high-throughput FAIRE. However, the therapeutic interpretation
    remains unresolved: a compound or degrader that reduces an Ewing chromatin signature could act
    by direct fusion-pathway reversal, by ETV6 or NuRD/HDAC/LSD1 modifier biology, by reduced EWS-FLI1
    expression, or by general toxicity. A mechanism-resolved chromatin perturbation screen would
    convert this chromatin phenotype into a decision rule for prioritizing causal nodes and cloud-lab-ready
    follow-up experiments.
  proposed_experiments:
  - experiment_id: exp_ewing_automated_chromatin_reversal_screen
    name: Automated EWS-FLI1 chromatin-reversal perturbation screen
    description: >-
      Run an automated plate-based chromatin-accessibility screen in Ewing sarcoma models using HT-FAIRE,
      ATAC-qPCR, or low-input ATAC-seq readouts at sentinel EWS-FLI1 GGAA enhancers, ETV6-competed
      short GGAA elements, and repressed mesenchymal enhancers. Screen annotated epigenetic compounds,
      targeted degraders, kinase/chemical-probe libraries, and EWS-FLI1 or ETV6 perturbation controls,
      then triage hits by matched viability, fusion expression, enhancer activity, and transcriptional
      rescue.
    experiment_type:
      preferred_term: automated high-throughput chromatin-accessibility perturbation screen
    model_systems:
    - name: Ewing sarcoma chromatin-accessibility screening panel
      description: >-
        EWS-FLI1-positive Ewing sarcoma cell lines with sentinel GGAA enhancers and matched orthogonal
        chromatin, expression, and viability assays.
      experimental_model_type: CELL_LINE
      organism:
        preferred_term: human
        term:
          id: NCBITaxon:9606
          label: Homo sapiens
      publication: PMID:26929321
      modeled_mechanisms:
      - target: GGAA Microsatellite Enhancer Reprogramming
        description: Measures whether perturbations reverse fusion-dependent nucleosome depletion at GGAA enhancers.
      - target: ETV6 GGAA Counter-Regulation
        description: Tests whether ETV6-directed perturbation produces a separable short-GGAA enhancer state.
      - target: NuRD-LSD1 Transcriptional Repression
        description: Tests whether chromatin-repressive modifiers drive rescue of lineage or tumor-suppressive enhancers.
    perturbations:
    - name: Epigenetic compound and degrader library
      target: pathophysiology#GGAA Microsatellite Enhancer Reprogramming
      description: >
        Apply annotated epigenetic inhibitors, targeted degraders, and chemical probe libraries with
        dose and time gradients suitable for automated liquid handling.
    - name: EWS-FLI1 and ETV6 perturbation controls
      target: pathophysiology#EWS-FLI1 Fusion Oncogene
      description: >
        Include acute fusion knockdown or degron withdrawal, ETV6 degradation or knockdown, and vehicle
        controls to calibrate chromatin-reversal directionality.
      genes:
      - preferred_term: EWSR1
        term:
          id: hgnc:3508
          label: EWSR1
      - preferred_term: FLI1
        term:
          id: hgnc:3749
          label: FLI1
      - preferred_term: ETV6
        term:
          id: hgnc:3495
          label: ETV6
    readouts:
    - name: Sentinel chromatin-accessibility reversal
      target: pathophysiology#GGAA Microsatellite Enhancer Reprogramming
      description: >
        Quantify accessibility at EWS-FLI1-activated GGAA enhancers, ETV6- competed short GGAA elements,
        and fusion-repressed mesenchymal enhancers.
      biological_processes:
      - preferred_term: chromatin remodeling
        term:
          id: GO:0006338
          label: chromatin remodeling
      assays:
      - preferred_term: HT-FAIRE
      - preferred_term: ATAC-qPCR
      - preferred_term: low-input ATAC-seq
      direction: NEGATIVE
    - name: Mechanism-resolved transcriptional rescue
      target: pathophysiology#Core Regulatory Circuitry Activation
      description: >
        Pair chromatin hits with targeted RNA-seq or Perturb-seq to determine whether KLF15/TCF4/NKX2-2
        circuitry, mesenchymal differentiation genes, EWS-FLI1 abundance, or generic stress pathways
        explain the response.
      biological_processes:
      - preferred_term: regulation of gene expression
        term:
          id: GO:0010468
          label: regulation of gene expression
      assays:
      - preferred_term: targeted RNA-seq
      - preferred_term: Perturb-seq
      - preferred_term: immunoblotting
      direction: NEGATIVE
    - name: Growth and toxicity separation
      target: pathophysiology#Tumor Cell Proliferation and Survival
      description: >
        Measure viability, apoptosis, and clonogenic growth in the same dose and time grid to separate
        mechanism-specific chromatin reversal from nonspecific cytotoxicity.
      biological_processes:
      - preferred_term: cell population proliferation
        term:
          id: GO:0008283
          label: cell population proliferation
      assays:
      - preferred_term: viability assay
      - preferred_term: apoptosis assay
      - preferred_term: clonogenic survival assay
      direction: NEGATIVE
    controls:
    - name: EWS-FLI1 knockdown positive control
      description: Calibrates the expected chromatin-accessibility direction for true fusion-pathway reversal.
    - name: Short-exposure viability control
      description: Flags compounds whose chromatin signal is secondary to acute cell loss or global toxicity.
    - name: Non-Ewing sarcoma comparator cells
      description: Tests whether hits reverse a Ewing-specific chromatin state rather than general chromatin accessibility.
    decision_criterion: >-
      A chromatin-reversal hit is prioritized when it reproducibly shifts sentinel EWS-FLI1 accessibility
      and transcription toward the fusion- withdrawal state at concentrations and times that precede
      broad cytotoxicity, and when the response maps to a declared mechanism node such as ETV6 competition,
      NuRD/HDAC/LSD1 repression, or EWS-FLI1 dosage.
    would_support:
    - pathophysiology#GGAA Microsatellite Enhancer Reprogramming
    - pathophysiology#ETV6 GGAA Counter-Regulation
    - pathophysiology#NuRD-LSD1 Transcriptional Repression
    - pathophysiology#Tumor Cell Proliferation and Survival
    would_refute:
    - pathophysiology#GGAA Microsatellite Enhancer Reprogramming
    - pathophysiology#ETV6 GGAA Counter-Regulation
    evidence:
    - reference: PMID:26929321
      reference_title: "High-throughput small molecule screen identifies inhibitors of aberrant chromatin accessibility."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "To explore whether chromatin accessibility could serve as a platform for small molecule screening, we adapted formaldehyde-assisted isolation of regulatory elements (FAIRE), a chemical method to enrich for nucleosome-depleted genomic regions, as a high-throughput, automated assay."
      explanation: Supports the feasibility of automated chromatin-accessibility screening in this disease context.
    - reference: PMID:26929321
      reference_title: "High-throughput small molecule screen identifies inhibitors of aberrant chromatin accessibility."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "After demonstrating the validity and robustness of this approach, we applied this method to screen an epigenetically targeted small molecule library by evaluating regions of aberrant nucleosome depletion mediated by EWSR1-FLI1, the chimeric transcription factor critical for the bone and soft tissue tumor Ewing sarcoma."
      explanation: Supports using EWS-FLI1-dependent accessibility regions as the primary assay signal.
    - reference: PMID:40215343
      reference_title: "(GGAA)(3)-Based TF-PROTACs Enable Targeted Degradation of ETV6 to Inhibit Ewing Sarcoma Growth."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Recent studies identified ETV6 as a vulnerability in Ewing sarcoma, where it competes with EWS::FLI1 at short GGAA repeats to restrain EWS::FLI1 function."
      explanation: Supports including ETV6 perturbation as an orthogonal enhancer-state control.
  evidence:
  - reference: PMID:22086061
    reference_title: "Tumor-specific retargeting of an oncogenic transcription factor chimera results in dysregulation of chromatin and transcription."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Thus, the EWS-FLI chimera acquired chromatin-altering activity, leading to mistargeting, chromatin disruption, and ultimately, transcriptional dysregulation."
    explanation: Establishes the EWS-FLI1 chromatin-altering phenomenon that motivates the knowledge gap.
  - reference: PMID:26929321
    reference_title: "High-throughput small molecule screen identifies inhibitors of aberrant chromatin accessibility."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Capitalizing on precise differences in chromatin accessibility for drug discovery efforts offers significant advantages because it does not depend on the a priori selection of a single molecular target and may detect novel biologically relevant pathways."
    explanation: Supports chromatin-signature screening as a target-agnostic route to mechanism discovery.
- discussion_id: gap_ewing_replication_stress_response
  prompt: >-
    Which EWS-FLI1-induced DHX9/R-loop, SLFN11 fork-blocking, BRCA1, STAG2, and USP1-survivin states
    determine whether replication stress causes chemosensitivity, PARP/USP1/ATR inhibitor vulnerability,
    or survival and relapse?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#DHX9 Sequestration During Topoisomerase Stress
  - pathophysiology#Transcription-Coupled R-loop Accumulation
  - pathophysiology#STAG2-Modified Enhancer State
  - pathophysiology#Tumor Cell Proliferation and Survival
  - treatments#Neoadjuvant Chemotherapy
  rationale: >-
    Ewing sarcoma is sensitive to genotoxic chemotherapy, and EWS-FLI1 creates R-loops, replication
    stress, SLFN11-dependent fork blocking, and homologous-recombination defects. However, high-risk
    and relapsed tumors survive therapy, and it is not yet clear which molecular stress-state measurements
    predict response to PARP, ATR, USP1, or chemotherapy combinations.
  proposed_experiments:
  - experiment_id: exp_ewing_replication_stress_pharmacodynamic_panel
    name: Replication-stress pharmacodynamic response panel
    description: >-
      Profile matched diagnosis-relapse samples, patient-derived cultures, and Ewing sarcoma cell
      lines under etoposide, doxorubicin, PARP inhibition, USP1 inhibition, and combinations. Perturb
      EWS-FLI1, DHX9, SLFN11, BRCA1, USP1, and BIRC5 to separate primary fusion-induced stress, fork
      blocking, and survival adaptation.
    experiment_type:
      preferred_term: perturbation-response pharmacodynamic experiment
    model_systems:
    - name: Matched Ewing sarcoma patient-derived culture and cell-line panel
      description: >-
        Human Ewing sarcoma cultures and cell lines stratified by therapy response, STAG2 status,
        and replication-stress markers.
      experimental_model_type: PRIMARY_CELL_CULTURE
      organism:
        preferred_term: human
        term:
          id: NCBITaxon:9606
          label: Homo sapiens
      publication: PMID:37478161
      modeled_mechanisms:
      - target: DHX9 Sequestration During Topoisomerase Stress
        description: Measures DHX9/R-loop and SLFN11 fork-blocking states under treatment.
      - target: Transcription-Coupled R-loop Accumulation
        description: Measures R-loops, replication stress, and DNA repair state under treatment.
    perturbations:
    - name: Genotoxic and targeted stress perturbation
      target: pathophysiology#Transcription-Coupled R-loop Accumulation
      description: >
        Compare standard genotoxic agents with PARP and USP1 inhibition under fusion knockdown or
        repair/survival gene perturbation.
      genes:
      - preferred_term: DHX9
        term:
          id: hgnc:2750
          label: DHX9
      - preferred_term: SLFN11
        term:
          id: hgnc:26633
          label: SLFN11
      - preferred_term: BRCA1
        term:
          id: hgnc:1100
          label: BRCA1
      - preferred_term: USP1
        term:
          id: hgnc:12607
          label: USP1
      - preferred_term: BIRC5
        term:
          id: hgnc:593
          label: BIRC5
    readouts:
    - name: R-loop, fork-blocking, and homologous-recombination response
      target: pathophysiology#DHX9 Sequestration During Topoisomerase Stress
      description: >
        Measure R-loop burden, DHX9 occupancy, SLFN11 chromatin recruitment, replication fork stress,
        gamma-H2AX, RAD51 foci, BRCA1 localization, and transcription-coupled DNA damage after treatment.
      biological_processes:
      - preferred_term: double-strand break repair via homologous recombination
        term:
          id: GO:0000724
          label: double-strand break repair via homologous recombination
      assays:
      - preferred_term: DRIP-seq
      - preferred_term: DNA fiber assay
      - preferred_term: immunofluorescence DNA repair foci assay
      direction: NEGATIVE
    - name: Cell survival under replication stress
      target: pathophysiology#Tumor Cell Proliferation and Survival
      description: >
        Quantify apoptosis, clonogenic survival, and drug synergy across chemotherapy, PARP inhibition,
        and USP1 inhibition.
      biological_processes:
      - preferred_term: cell population proliferation
        term:
          id: GO:0008283
          label: cell population proliferation
      assays:
      - preferred_term: clonogenic survival assay
      - preferred_term: apoptosis assay
      direction: NEGATIVE
    controls:
    - name: EWS-FLI1 knockdown or degron control
      description: Tests whether replication-stress markers are fusion-dependent.
    - name: Isogenic USP1 or BIRC5 rescue
      description: Separates USP1-survivin survival adaptation from upstream R-loop burden.
    decision_criterion: >-
      A predictive stress-state model is supported when baseline or early treatment-induced R-loop/BRCA1/USP1-survivin
      readouts reproducibly predict death, survival, or drug synergy across independent patient-derived
      models and are reversed by the corresponding genetic rescue or withdrawal.
    would_support:
    - pathophysiology#DHX9 Sequestration During Topoisomerase Stress
    - pathophysiology#Transcription-Coupled R-loop Accumulation
    - pathophysiology#Tumor Cell Proliferation and Survival
    would_refute:
    - pathophysiology#Transcription-Coupled R-loop Accumulation
    evidence:
    - reference: PMID:29513652
      reference_title: "EWS-FLI1 increases transcription to cause R-loops and block BRCA1 repair in Ewing sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Ewing sarcoma is highly sensitive to genotoxic agents such as etoposide, but the underlying molecular basis of this sensitivity is unclear."
      explanation: Supports the unresolved response-mechanism framing.
    - reference: PMID:37478161
      reference_title: "USP1 Expression Driven by EWS::FLI1 Transcription Factor Stabilizes Survivin and Mitigates Replication Stress in Ewing Sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Notably, USP1 inhibition sensitizes cells to doxorubicin and etoposide treatment."
      explanation: Supports USP1 as a testable stress-survival target.
    - reference: PMID:40721661
      reference_title: "EWS::FLI1-DHX9 interaction promotes Ewing sarcoma sensitivity to DNA topoisomerase 1 poisons by altering R-loop metabolism."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "We discovered that EWS::FLI1 prevents the resolution of R-loops induced by these drugs via sequestering DHX9 helicase, ultimately resulting in R-loop accumulation, replication stress, and genome instability."
      explanation: Supports testing DHX9/R-loop state as a predictive pharmacodynamic readout.
    - reference: PMID:25779942
      reference_title: "SLFN11 Is a Transcriptional Target of EWS-FLI1 and a Determinant of Drug Response in Ewing Sarcoma."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "RESULTS: EWS-FLI1 binds near the transcription start site of SLFN11 promoter and acts as a positive regulator of SLFN11 expression in Ewing sarcoma cells."
      explanation: Supports testing SLFN11 as an EWS-FLI1-driven predictive biomarker.
  evidence:
  - reference: PMID:37478161
    reference_title: "USP1 Expression Driven by EWS::FLI1 Transcription Factor Stabilizes Survivin and Mitigates Replication Stress in Ewing Sarcoma."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The mechanism by which EWS cells override activation of apoptosis or cellular senescence in response to increased replication stress is not known."
    explanation: Directly states the survival-under-replication-stress knowledge gap.
  - reference: PMID:40721661
    reference_title: "EWS::FLI1-DHX9 interaction promotes Ewing sarcoma sensitivity to DNA topoisomerase 1 poisons by altering R-loop metabolism."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "In turn, excessive DHX9 or reduced EWS::FLI1 levels render EwS cells resistant to the active metabolite of irinotecan (SN-38) independent of proliferation and global transcription rates."
    explanation: Supports unresolved resistance prediction involving DHX9 and fusion dosage.
- discussion_id: gap_ewing_stag2_cohesin_high_risk_mechanism
  prompt: >-
    In STAG2-altered Ewing sarcoma, which causal arm best explains high-risk disease: multimeric
    GGAA enhancer amplification, PRC2/CTCF chromatin rewiring, replication-fork repair vulnerability,
    or a context-specific combination of these mechanisms?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#STAG2-Modified Enhancer State
  - pathophysiology#GGAA Microsatellite Enhancer Reprogramming
  - pathophysiology#DHX9 Sequestration During Topoisomerase Stress
  - pathophysiology#Transcription-Coupled R-loop Accumulation
  - phenotypes#Metastatic Disease
  rationale: >-
    The reviewed literature supports that STAG2 loss reshapes GGAA enhancer-promoter contacts and
    is clinically adverse, but the mechanism is not a single clean edge. EWS-FLI1-dependent long-GGAA
    contacts, EWS-FLI1- independent CTCF changes, PRC2 derepression, TP53 co-alteration, and replication-fork
    stress could each contribute differently across cohorts, ancestry backgrounds, and treatment
    states. Protein loss, mutation, enhancer occupancy and treatment sensitivity are distinct measurements.

    COG diagnostic IHC/EFS and Japanese post-profiling mutation/OS results do not establish an ancestry
    effect. NR0B1 repeats were longer in African than European healthy subjects in PMID:22749036,
    the opposite of the OpenScientist cohesin report; no Japanese-repeat mechanism follows from that
    study. STAG2-dependent fork/HR findings from broader cancer models justify matched Ewing experiments,
    not a confirmed clinical predictive biomarker.
  proposed_experiments:
  - experiment_id: exp_ewing_stag2_primary_tumor_chromatin_ddr_atlas
    name: STAG2-stratified primary-tumor chromatin and DDR atlas
    description: >-
      Profile STAG2-positive and STAG2-negative primary and relapse Ewing sarcoma specimens with
      matched WGS, long-read GGAA microsatellite typing, RNA-seq, ATAC-seq or CUT&Tag, H3K27ac/H3K27me3,
      CTCF/cohesin occupancy, and DNA-damage response markers. Pair the tumor atlas with isogenic
      STAG2 rescue or knockout in Ewing sarcoma cultures to separate enhancer, PRC2/CTCF, and replication-stress
      arms.
    experiment_type:
      preferred_term: STAG2-stratified multi-omic mechanism atlas
    model_systems:
    - name: STAG2-positive and STAG2-negative Ewing sarcoma tumor cohort
      description: >-
        Banked diagnostic and relapse Ewing sarcoma tumors with STAG2 protein status, mutation calls,
        clinical outcome, and ancestry-aware GGAA repeat genotyping.
      experimental_model_type: OTHER
      organism:
        preferred_term: human
        term:
          id: NCBITaxon:9606
          label: Homo sapiens
      publication: PMID:36221002
      modeled_mechanisms:
      - target: STAG2-Modified Enhancer State
        description: Tests whether STAG2 loss produces the same high-risk chromatin state in primary tumors.
      - target: GGAA Microsatellite Enhancer Reprogramming
        description: Measures multimeric GGAA enhancer amplification and enhancer-promoter contact strength.
      - target: Transcription-Coupled R-loop Accumulation
        description: Measures whether STAG2 loss adds fork and repair stress to the fusion-driven DDR state.
    perturbations:
    - name: STAG2 rescue or knockout
      target: pathophysiology#STAG2-Modified Enhancer State
      description: >
        Restore STAG2 in STAG2-deficient Ewing sarcoma models and remove STAG2 in matched STAG2-proficient
        models while stratifying by TP53 status.
      genes:
      - preferred_term: STAG2
        term:
          id: hgnc:11355
          label: STAG2
    readouts:
    - name: Enhancer, PRC2, and CTCF arm partition
      target: pathophysiology#STAG2-Modified Enhancer State
      description: >
        Quantify EWS-FLI1 occupancy at short and long GGAA repeats, enhancer-promoter contacts, H3K27ac,
        H3K27me3, CTCF loops, and neurodevelopmental or migratory target-gene expression.
      biological_processes:
      - preferred_term: chromosome organization
        term:
          id: GO:0051276
          label: chromosome organization
      assays:
      - preferred_term: long-read microsatellite genotyping
      - preferred_term: Capture Hi-C
      - preferred_term: ATAC-seq
      - preferred_term: CUT&Tag
      direction: POSITIVE
    - name: Replication-fork and repair-stress response
      target: pathophysiology#Transcription-Coupled R-loop Accumulation
      description: >
        Measure DNA fiber fork progression, gamma-H2AX, RAD51 foci, PARP/ATR inhibitor response,
        and chemotherapy response by STAG2 state.
      biological_processes:
      - preferred_term: DNA replication
        term:
          id: GO:0006260
          label: DNA replication
      assays:
      - preferred_term: DNA fiber assay
      - preferred_term: immunofluorescence DNA repair foci assay
      - preferred_term: drug-response matrix
      direction: NEGATIVE
    controls:
    - name: STAG2-wild-type matched tumors
      description: Stage-, site-, age-, and ancestry-matched tumors retaining STAG2 expression.
    - name: Isogenic rescue controls
      description: STAG2 restoration or knockout controls that separate STAG2 effects from cell-line background.
    decision_criterion: >-
      The STAG2 high-risk model is strengthened if STAG2-negative primary tumors reproduce long-GGAA
      enhancer amplification and if isogenic rescue reverses the predicted enhancer, PRC2/CTCF, or
      DDR arm. A single dominant arm would be prioritized only if it predicts clinical outcome and
      drug response better than the alternatives.
    would_support:
    - pathophysiology#STAG2-Modified Enhancer State
    - pathophysiology#GGAA Microsatellite Enhancer Reprogramming
    - pathophysiology#Transcription-Coupled R-loop Accumulation
    would_refute:
    - pathophysiology#STAG2-Modified Enhancer State
    evidence:
    - reference: PMID:39487368
      reference_title: "STAG2 loss in Ewing sarcoma alters enhancer-promoter contacts dependent and independent of EWS::FLI1."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Subsequent genomic profiling and high-resolution chromatin interaction data from Capture Hi-C indicated that cohesin-STAG2 facilitates communication between EWS::FLI1-bound long GGAA repeats, presumably acting as neoenhancers, and their target promoters."
      explanation: Supports measuring STAG2-dependent long-GGAA enhancer-promoter contacts.
    - reference: PMID:36221002
      reference_title: "Adverse prognostic impact of the loss of STAG2 protein expression in patients with newly diagnosed localised Ewing sarcoma: A report from the Children's Oncology Group."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "CONCLUSION: STAG2 loss of expression is identified in a population of patients without identifiable STAG2 mutations and carries a poor prognosis."
      explanation: Supports the need for primary-tumor clinical stratification by STAG2 loss.
  evidence:
  - reference: PMID:39487368
    reference_title: "STAG2 loss in Ewing sarcoma alters enhancer-promoter contacts dependent and independent of EWS::FLI1."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Changes in CTCF-dependent chromatin contacts involving signature genes, unrelated to EWS::FLI1 binding, were also identified."
    explanation: Supports the unresolved CTCF arm of the STAG2 mechanism.
  - reference: PMID:36221002
    reference_title: "Adverse prognostic impact of the loss of STAG2 protein expression in patients with newly diagnosed localised Ewing sarcoma: A report from the Children's Oncology Group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "CONCLUSION: STAG2 loss of expression is identified in a population of patients without identifiable STAG2 mutations and carries a poor prognosis."
    explanation: Supports STAG2 protein loss as a clinically meaningful high-risk state.
  - reference: PMID:25223734
    reference_title: "Genomic landscape of Ewing sarcoma defines an aggressive subtype with co-association of STAG2 and TP53 mutations."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Strikingly, STAG2 mutations and CDKN2A deletions were mutually exclusive, as confirmed in Ewing sarcoma cell lines."
    explanation: Supports the need to stratify STAG2 effects against other high-risk genomic routes.
  - reference: PMID:30975996
    reference_title: A requirement for STAG2 in replication fork progression creates a targetable synthetic lethality in cohesin-mutant cancers.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: As a consequence, STAG2 mutation confers synthetic lethality with DNA double-strand break repair genes and increased sensitivity to select cytotoxic chemotherapeutic agents and PARP or ATR inhibitors.
    explanation: >-
      Broader cancer-cell data motivate Ewing-specific testing; this is not established patient selection
      evidence.
  - reference: PMID:22749036
    reference_title: EWS/FLI-responsive GGAA microsatellites exhibit polymorphic differences between European and African populations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: the NR0B1 microsatellite in African subjects was significantly larger, harboring more repeat motifs, a greater number of repeat segments, and longer consecutive repeats, than in European subjects.
    explanation: >-
      Corrects the direction of the report ancestry claim; healthy-donor repeat structure does not
      explain STAG2-specific prognosis.
- discussion_id: gap_ewing_stag2_loss_to_fusion_protein_abundance
  prompt: >-
    By what route does STAG2 loss raise EWS-FLI1 protein abundance, and does that increase feed
    back into the enhancer phenotype rather than merely accompanying it?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#STAG2-Modified Enhancer State
  - pathophysiology#EWS-FLI1 Dosage and State Plasticity
  - pathophysiology#GGAA Microsatellite Enhancer Reprogramming
  rationale: >-
    This entry curates the two ends of this link and nothing in between. The multiomic STAG2
    loss-of-function study reports increased EWS-FLI1 protein abundance alongside the redistribution
    of fusion binding from short toward multimeric GGAA repeats, and does not account for the
    abundance change. Separately, the dosage node holds a regulated turnover pathway and a window
    whose output is non-monotonic in both directions, with TRIM8-mediated degradation as the curated
    mechanism keeping fusion protein within it. No study has asked whether STAG2 loss acts on that
    pathway. This matters for interpretation rather than completeness: if the protein rise is
    causal, the enhancer redistribution reported in STAG2-null cells is partly a dose effect
    operating through the curated window rather than a purely architectural consequence of losing
    cohesin-STAG2, and the two published mechanisms would not be independent. Deubiquitination is
    the obvious place to look, since USP19 stabilizes the fusion and its depletion lowers fusion
    levels, giving a manipulable step rather than an open-ended search. Measuring fusion
    ubiquitination, half-life, and USP19 and TRIM8 levels in isogenic STAG2 wild-type and null
    pairs, then holding fusion dose constant with a degron while removing STAG2, would separate the
    two.
  evidence:
  - reference: PMID:41950086
    reference_title: "STAG2 loss amplifies EWS-FLI1-driven microsatellite enhancer activity promoting Ewing sarcoma aggressiveness."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Despite increased EWS-FLI1 protein abundance, STAG2 loss eliminates over 40% of EWS-FLI1 binding sites"
    explanation: >-
      Records the unexplained protein-abundance increase that motivates this gap, and shows it
      running opposite to the loss of binding sites, which is why the two cannot be read as one
      effect.
  - reference: PMID:30700749
    reference_title: USP19 deubiquitinates EWS-FLI1 to regulate Ewing sarcoma growth.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Constant EWS-FLI1 protein turnover is regulated by the ubiquitin proteasome system."
    explanation: >-
      Establishes that a defined turnover pathway exists to be tested as the route for the
      STAG2-associated protein increase.
  - reference: PMID:30700749
    reference_title: USP19 deubiquitinates EWS-FLI1 to regulate Ewing sarcoma growth.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Depletion of USP19 resulted in diminished EWS-FLI1 protein levels and, vice versa, upregulation of active USP19 stabilized the fusion protein."
    explanation: >-
      Identifies a specific, manipulable step in that turnover pathway, which is what makes the
      proposed test concrete. It does not itself connect USP19 to STAG2.
- discussion_id: gap_ewing_adult_onset_extraskeletal_origin
  prompt: >-
    Do the Ewing sarcomas that present after age 40, which are predominantly extraskeletal and
    carry markedly worse survival, arise from the same permissive progenitor state as pediatric
    tumors, or is the developmental model narrower in scope than the entry implies?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Permissive Progenitor Cell State
  - pathophysiology#IGF-1/YAP1 Developmental Cooperation
  - has_subtypes#Extraosseous Ewing Sarcoma
  rationale: >-
    The permissive-progenitor and IGF-1/YAP1 mechanisms curated here are both anchored to a
    developmental window: an early mesenchymal or neural crest-derived chromatin state, and a
    pubertal growth-factor signal that fits the adolescent incidence peak. Registry data show the
    disease extends well past that window. In a SEER cohort of 2,780 patients, 383 were diagnosed
    at 40 years or older, and those patients were roughly twice as likely to have extraskeletal
    primaries and had substantially worse survival. This is a question about cell of origin, not
    about age at initiation: a late diagnosis does not date the initiating event, so persistence of
    a permissive progenitor and a genuinely different route are both live. The registry cohort also
    predates routine molecular confirmation, and the source itself notes that the higher rate of
    soft-tissue and PNET-coded tumors in older patients may reflect clinical naming rather than
    tumor biology, so part of the age difference may be classification artifact. That confound is
    itself part of what needs resolving. Age-stratified DNA methylation and single-cell profiling
    of molecularly confirmed adult-onset versus pediatric tumors would settle whether the curated
    developmental mechanism covers them.
  evidence:
  - reference: PMID:22959474
    reference_title: "Characteristics and outcomes of patients with Ewing sarcoma over 40 years of age at diagnosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "2780 patients were identified; including 383 patients diagnosed ≥40 years"
    explanation: Establishes that adult-onset disease is a substantial minority rather than a negligible tail.
  - reference: PMID:22959474
    reference_title: "Characteristics and outcomes of patients with Ewing sarcoma over 40 years of age at diagnosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients ≥40 years of age were more likely to have extra-skeletal tumors (66.1% vs. 31.7%; p < 0.001)"
    explanation: >-
      Shows the adult-onset group differs in primary site, which is the observation that makes a
      shared developmental origin an open question rather than an assumption.
  - reference: PMID:22959474
    reference_title: "Characteristics and outcomes of patients with Ewing sarcoma over 40 years of age at diagnosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Five-year survival for those age ≥40 and age <40 were 40.6% and 54.3%, respectively"
    explanation: Establishes the clinical stakes of resolving whether adult-onset disease shares the curated mechanism.
  - reference: PMID:22959474
    reference_title: "Characteristics and outcomes of patients with Ewing sarcoma over 40 years of age at diagnosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Since older adults had a higher incidence of both soft tissue tumors and tumors classified as PNET, it is possible that our findings reflect this widely used nomenclature rather than a true increase in neural differentiation of tumors arising in older adults."
    explanation: >-
      The authors' own caution that part of the site difference may be a naming convention rather
      than biology, which is why this gap requires molecularly confirmed cases rather than registry
      codes.
disease_term:
  preferred_term: Ewing sarcoma
  term:
    id: MONDO:0012817
    label: Ewing sarcoma

classifications:
  icdo_morphology:
    classification_value: Sarcoma
  harrisons_chapter:
  - classification_value: ONCOLOGY_HEMATOLOGY
  nih_research_priority:
  - classification_value: NIH_HT_68_childhood_adolescent_young_adult_aya_cancer
    notes: Aggressive bone/soft-tissue sarcoma of children and adolescents/young adults (EWSR1-FLI1 fusion) — flagship exemplar for NIH Highlighted Topic 68 (childhood and AYA cancer research).
datasets:
- accession: ega:EGAS00001000839
  title: Targeting the DNA Repair Pathway in Ewing Sarcoma
  description: Ewing’s Sarcoma is a bone and soft tissue tumor that primarily affects adolescents and young adults. With current therapies, 70% of patients with localized disease survive but survival for metastatic and recurrent disease is poor. Whole genome sequencing of 19 Ewing’s Sarcoma tumors showed that STAG2 was mutated in 10% (2/19) of the tumors and STAG2 protein was absent in 14% (13/106) tumors by immunohistochemical staining. Previous studies have shown that glioblastoma cells lacking STAG2 are more sensitive to poly-ADP ribose polymerase (PARP) inhibitors. We found that Ewing’s Sarcoma cell lines are sensitive to PARP inhibitors irrespective of STAG2 protein expression.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  notes: 'European Genome-phenome Archive study, matched because the disease is named in the study''s own title ("Ewing Sarcoma"); description-level mentions were not accepted. EGA study_type: Other. Controlled access -- data require a Data Access Agreement. EGA metadata retrieved 2026-08-01.'
- accession: ega:EGAS00001000855
  title: Genomic landscape of Ewing sarcoma (ICGC project)
  description: The Ewing sarcoma project aims to sequence 100 complete genomes of cells of patients suffering from this disease. It is an initiative of great projection, since this is the second most common bone tumor in children and teenagers. The goal of the project is to establish the catalogue of somatic mutations that may cooperate with EWS-ETS fusion in the development of the tumor. The Ewing sarcoma project aims to perform 100 whole genome sequencing of germline and tumor DNA as well as at least 50 RNA-seq from tumors. Correlations between molecular profiles and clinical features will be established.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  publication: PMID:25223734
  notes: 'European Genome-phenome Archive study, matched because the disease is named in the study''s own title ("Ewing Sarcoma"); description-level mentions were not accepted. EGA study_type: Other. Controlled access -- data require a Data Access Agreement. EGA metadata retrieved 2026-08-01.'
- accession: ega:EGAS00001002161
  title: Methylation of Ewing sarcoma tumors (ICGC)
  description: Ewing sarcoma (ES) is a primary bone tumor initiated by an EWSR1-ETS gene fusion. To characterize the methylation of Ewing sarcoma, reduced representation bisulfite sequencing was performed.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  publication: PMID:28134926
  notes: 'European Genome-phenome Archive study, matched because the disease is named in the study''s own title ("Ewing Sarcoma"); description-level mentions were not accepted. EGA study_type: Other. Controlled access -- data require a Data Access Agreement. EGA metadata retrieved 2026-08-01.'
- accession: dbgap:phs000804
  title: Genomic Sequencing of Ewing Sarcoma
  description: Pediatric Ewing sarcoma is a pediatric cancer that primarily arises from the bone. It is characterized by chimeric fusions of the EWS gene and an ETS family transcription factor. In this study, we performed massively parallel sequencing of a larger collection of Ewing sarcoma tumors to define the genomic landscape of this disease. We found that these tumors are among of the most genetically normal cancers currently characterized. There was also a marked absence of recurrent mutations in immediately targetable signaling transduction pathway genes.
  notes: Located via OmicsDI, which aggregates across omics repositories; this record comes from dbgap. Only repositories with no other discovery route in this project and with a working accession resolver are curated from OmicsDI -- GEO, ArrayExpress, PRIDE, MetaboLights and EGA hits are excluded as duplicates of dedicated passes. Matched because the disease is named in the dataset's own title ("Ewing Sarcoma"). Retrieved 2026-08-02.
- accession: dbgap:phs001549
  title: Genome-wide Association Study and Meta-Analysis of Ewing Sarcoma
  description: We combined a set of 122 French Ewing sarcoma (EWS) cases from the Institut Curie, 19 EWS cases from the National Cancer Institute (NCI) Center for Cancer Research (CCR), and 29 EWS cases from the NCI Bone Disease and Injury Study. All EWS cases were confirmed by medical record review and the presence of a specific EWSR1-ETS translocation were noted when data was available. Each participant provided informed consent and each participating study was approved by the Institutional Review Boards of their study center.
  notes: Located via OmicsDI, which aggregates across omics repositories; this record comes from dbgap. Only repositories with no other discovery route in this project and with a working accession resolver are curated from OmicsDI -- GEO, ArrayExpress, PRIDE, MetaboLights and EGA hits are excluded as duplicates of dedicated passes. Matched because the disease is named in the dataset's own title ("Ewing Sarcoma"). Retrieved 2026-08-02.
- accession: massive:MSV000082954
  title: STAG2 Loss Rewires Oncogenic and Developmental Programs to Promote Metastasis in Ewing Sarcoma
  description: Adane B, Alexe G, Seong BKA, Lu D, Hwang E, Hnisz D, Lareau CA, Ross L, Lin S, Dela Cruz FS, Richardson M, Weintraub AS, Wang S, Balboni-Iniguez A, Dharia NV, Conway AS, Robichaud AL, Tanenbaum B, Krill-Burger JM, Vazquez F, Schenone M, Berman JN, Kung A, Carr SA, Aryee MJ, Young RA, Crompton BD, Stegmaier K. 2021 Cancer Cell. The core cohesin subunit STAG2 is recurrently mutated in Ewing sarcoma but its biological role is less clear. Herein, we demonstrate that cohesin complexes containing STAG2 occupy enhancer and polycomb repressive complex (PRC2) marked regulatory regions.
  notes: Located via OmicsDI, which aggregates across omics repositories; this record comes from massive. Only repositories with no other discovery route in this project and with a working accession resolver are curated from OmicsDI -- GEO, ArrayExpress, PRIDE, MetaboLights and EGA hits are excluded as duplicates of dedicated passes. Matched because the disease is named in the dataset's own title ("Ewing Sarcoma"). Retrieved 2026-08-02.
animal_models:
- name: Neural-crest-targeted EWSR1-FLI1 zebrafish
  species: Zebrafish
  genotype: Neural-crest-targeted EWSR1::FLI1 expression
  description: >-
    Lineage-targeted fusion expression produced neural crest-to-mesoderm reprogramming and lethal
    Ewing-like tumors. This establishes origin and reprogramming within the zebrafish model, not
    definitive ancestry of human tumors.
  publication: PMID:41072418
  modeled_mechanisms:
  - target: Permissive Progenitor Cell State
    description: Tests lineage-specific fusion tolerance and transformation.
  evidence:
  - reference: PMID:41072418
    reference_title: Origin of Ewing sarcoma by embryonic reprogramming of neural crest to mesoderm.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Neural crest-derived cells uniquely tolerate expression of EWSR1::FLI1, and targeted expression of EWSR1::FLI1 in these cells generates lethal Ewing sarcomas.
    explanation: >-
      Lineage-specific tolerance and tumor formation in zebrafish support a neural crest origin in
      this model, not definitive human ancestry.
- name: EWS-FLI1-transduced human embryonic MSC xenograft
  species: Mouse
  genotype: Immunodeficient hosts xenografted with EWS::FLI1-transduced human embryonic MSCs
  description: >-
    Tests tumorigenicity of engineered early human mesenchymal cells. The implanted cell origin is
    known, but this does not trace spontaneous human disease.
  publication: PMID:41136396
  modeled_mechanisms:
  - target: Permissive Progenitor Cell State
    description: Tests tumorigenicity of an experimentally permissive progenitor state.
  evidence:
  - reference: PMID:41136396
    reference_title: "EWS::FLI1 expression in human embryonic mesenchymal stem cells leads to transcriptional reprograming, defective DNA damage repair and Ewing sarcoma."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Xenografting of EWS::FLI1-transduced heMSCs results in the formation of tumors expressing characteristic ES markers.
    explanation: >-
      Animal-host tumorigenicity validation, separated from the in-vitro culture model.
diagnosis:
- name: Integrated Histologic and Molecular Diagnosis
  description: >-
    Core biopsy planned by the sarcoma team provides material for morphology, CD99/NKX2.2 immunohistochemistry
    and fusion characterization. Confirm a compatible FET-ETS fusion. Interpret EWSR1 break-apart
    FISH with care because EWSR1 rearrangements occur in other tumors; RNA fusion testing can resolve
    the partner or cryptic events. Exclude CIC-rearranged, BCOR-altered and EWSR1-non-ETS round-cell
    sarcomas.
  diagnosis_term:
    preferred_term: integrated histologic and molecular diagnosis
    description: The combined biopsy, immunohistochemical and molecular workflow is broader than any one component test.
    term:
      id: NCIT:C18020
      label: Diagnostic Procedure
  evidence:
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Definitive ES diagnosis should be performed (or reviewed) at a reference sarcoma center and based on sufficient biopsy material for conventional histology, immunohistochemistry, and molecular pathology
    explanation: >-
      Integrated diagnostic approach requiring adequate tissue and specialist interpretation.
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: All cases of ES harbor a FET-ETS fusion.
    explanation: >-
      Includes rare FUS-containing fusions and distinguishes other round-cell sarcomas.
- name: Local and Metastatic Staging
  description: >-
    MRI defines the primary lesion and local extent. Chest imaging and whole-body assessment evaluate
    pulmonary and skeletal spread. Routine bilateral marrow biopsy is no longer standard when modern
    skeletal imaging shows no bone metastases; testing depends on the clinical context.
  diagnosis_term:
    preferred_term: Diagnostic Imaging Testing
    description: The imaging component of local and metastatic staging; clinical and tissue assessment remain described separately. Clinical Staging (NCIT:C200641) was considered but is outside the permitted treatment-action ontology branch.
    term:
      id: NCIT:C16502
      label: Diagnostic Imaging Testing
  evidence:
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Bilateral iliac bone marrow biopsy is no longer standard in staging, because of the extremely low rate of bone marrow involvement in the absence of bone metastasis detection by BS or PET
    explanation: >-
      Guideline limits routine marrow biopsy rather than excluding marrow disease.
  - reference: PMID:25691401
    reference_title: "Diagnosis and treatment of Ewing sarcoma of the bone: a review article."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Computed tomography (CT) is useful for depicting extraskeletal soft tissue masses, destruction of the bone cortex, and pulmonary metastasis
    explanation: >-
      Clinical imaging support for local and pulmonary staging.
stages:
- name: Localized Disease
  description: >-
    No detectable distant metastases on staging. Occult dissemination remains clinically important,
    so systemic chemotherapy is required in addition to local control.
  evidence:
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: in the past, 80–90% of patients with apparently localized disease died when treatment was reduced to a local approach.
    explanation: >-
      Historical evidence summarized by the guideline explains systemic treatment despite localized
      staging.
- name: Metastatic Disease at Diagnosis
  description: >-
    Distant disease, commonly in lung, bone or bone marrow. Prognosis and local treatment decisions
    depend on extent and metastatic distribution; lung-only and multifocal extrapulmonary disease
    are not equivalent risk groups.
  evidence:
  - reference: PMID:39158802
    reference_title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Disease dissemination is predominantly hematogenous, being lung, bones, and bone marrow as the most common metastatic sites.
    explanation: >-
      Supports distribution of metastatic disease.
- name: Relapsed or Refractory Disease
  description: >-
    Recurrent disease after initial treatment or progression despite therapy. Salvage treatment and
    local control are individualized; clinical trials are important because durable outcomes remain
    poor.
  evidence:
  - reference: PMID:32078813
    reference_title: "Cabozantinib in patients with advanced Ewing sarcoma or osteosarcoma (CABONE): a multicentre, single-arm, phase 2 trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The outcome is particularly poor, with a median overall survival of less than 12 months and a standard management remaining to be established
    explanation: >-
      The CABONE publication describes its advanced/recurrent treatment setting, not the prognosis
      of all newly diagnosed Ewing sarcoma.
clinical_trials:
- name: NCT00006734
  status: COMPLETED
  phase: PHASE_III
  description: >-
    COG AEWS0031 randomized interval-compressed versus standard-interval VDC/IE in localized disease.
    Among 568 eligible patients, five-year EFS was 73% versus 65%, with similar toxicity. These are
    trial-population estimates, not an individual prognosis.
  notes: >-
    Registry status was checked on 2026-09-05. Published primary results do not imply
    that all follow-up is complete. The status is the current administrative registry
    value, not an efficacy conclusion.
  evidence:
  - reference: PMID:23091096
    reference_title: "Randomized controlled trial of interval-compressed chemotherapy for the treatment of localized Ewing sarcoma: a report from the Children's Oncology Group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: EFS at a median of 5 years was 65% in the standard arm and 73% in the intensified arm (P=.048).
    explanation: >-
      Randomized efficacy result for interval compression.
  - reference: url:https://clinicaltrials.gov/api/v2/studies/NCT00006734?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
    reference_title: https://clinicaltrials.gov/api/v2/studies/NCT00006734?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
    supports: SUPPORT
    evidence_source: OTHER
    snippet: '{"protocolSection":{"identificationModule":{"nctId":"NCT00006734","briefTitle":"Comparison of Combination Chemotherapy Regimens in Treating Patients With Ewing''s Sarcoma or Neuroectodermal Tumor"},"statusModule":{"overallStatus":"COMPLETED","completionDateStruct":{"date":"2023-06-30"},"lastUpdatePostDateStruct":{"date":"2023-08-03"}}}}'
    explanation: ClinicalTrials.gov structured registry fields retrieved on 2026-09-05 identify this trial and report COMPLETED. This is administrative status, separate from the published efficacy results; the record also gives its last update and completion date.
- name: ISRCTN92192408
  status: COMPLETED
  phase: PHASE_III
  description: >-
    EURO EWING 2012 compared VDC/IE-based and VIDE-based strategies. The VDC/IE strategy improved
    outcomes and reduced treatment burden. A separate second randomization in 272 eligible patients
    found no benefit from adding zoledronic acid to consolidation chemotherapy.
  notes: >-
    Primary registry verification identifies EE2012 as ISRCTN92192408 with secondary
    identifier EudraCT 2012-002107-17 and completed status. PMID:36522207 and
    PMID:41832299 print ISRCTN54540667, which the WHO ICTRP record identifies as the
    unrelated PIL-FAST stroke trial. The published identifier is retained verbatim in
    evidence documenting this discrepancy; the curated trial key follows the verified
    Ewing registry record. Registry status was checked on 2026-09-05.
  evidence:
  - reference: PMID:36522207
    reference_title: "Comparison of two chemotherapy regimens in patients with newly diagnosed Ewing sarcoma (EE2012): an open-label, randomised, phase 3 trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Dose-intensive chemotherapy with vincristine, doxorubicin, cyclophosphamide, ifosfamide, and etoposide is more effective, less toxic, and shorter in duration
    explanation: >-
      EE2012 randomized evidence supports the VDC/IE approach over VIDE induction. The protocol also
      admitted Ewing-like sarcomas, a scope consideration when applying the result to modern molecular
      entities.
  - reference: PMID:41832299
    reference_title: "Addition of zoledronic acid to consolidation chemotherapy in Ewing sarcoma-EURO EWING 2012 (EE2012): an international, open-label, randomised controlled phase III trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Adding zoledronic acid did not improve clinical outcomes in ES.
    explanation: >-
      Published 2026 randomized result constrains translation of preclinical bone-targeting activity.
  - reference: ICTRP:ISRCTN92192408
    reference_title: Euro Ewing 2012
    supports: SUPPORT
    evidence_source: OTHER
    snippet: |-
      | Recruitment status | Completed |
      | Study type | Interventional |
      | Study design | Multi-centre international Phase III open-label randomized controlled trial (Treatment) |
    explanation: The WHO ICTRP record identifies EURO EWING 2012 as ISRCTN92192408, lists EudraCT2012-002107-17 as its secondary identifier, and reports completed status. These registry fields establish identity and administrative status, not treatment efficacy.
  - reference: PMID:36522207
    reference_title: 'Comparison of two chemotherapy regimens in patients with newly diagnosed Ewing sarcoma (EE2012): an open-label, randomised, phase 3 trial.'
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: The trial was registered with EudraCT, 2012-002107-17, and ISRCTN, 54540667.
    explanation: 'This exact published registration sentence documents the identifier discrepancy: the EudraCT number matches EURO EWING 2012, but the printed ISRCTN number resolves to a different trial. The quote is preserved unchanged and is not used to override the primary registry.'
  - reference: ICTRP:ISRCTN54540667
    reference_title: Paramedic Initiated Lisinopril For Acute Stroke
    supports: REFUTE
    evidence_source: OTHER
    snippet: |-
      ## Health condition(s) or problem(s) studied

      Stroke with high blood pressure
      Circulatory System
      Stroke
    explanation: 'Negative identity check only: ISRCTN54540667 is the PIL-FAST lisinopril/stroke trial, not EURO EWING 2012. This refutes that printed trial identifier, not the Ewing trial results; no stroke intervention is curated as Ewing therapy.'
- name: NCT02306161
  status: ACTIVE_NOT_RECRUITING
  phase: PHASE_III
  description: >-
    COG AEWS1221 found that adding ganitumab to interval-compressed VDC/IE did not improve EFS in newly diagnosed metastatic
    Ewing sarcoma. The negative result does not disprove developmental IGF-1/YAP1 cooperation: established
    metastatic tumor treatment and tumor initiation test different hypotheses.
  notes: >-
    Registry status was checked on 2026-09-05. Published primary results do not imply
    that all follow-up is complete. The status is the current administrative registry
    value, not an efficacy conclusion.
  evidence:
  - reference: PMID:36669140
    reference_title: "Randomized Phase III Trial of Ganitumab With Interval-Compressed Chemotherapy for Patients With Newly Diagnosed Metastatic Ewing Sarcoma: A Report From the Children's Oncology Group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The 3-year EFS estimates were 37.4% (95% CI, 29.3 to 45.5) for the standard arm and 39.1% (95% CI, 31.3 to 46.7) for the experimental arm
    explanation: >-
      AEWS1221 did not demonstrate improvement from adding the IGF1R antibody ganitumab to VDC/IE
      in newly diagnosed metastatic disease.
  - reference: url:https://clinicaltrials.gov/api/v2/studies/NCT02306161?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
    reference_title: https://clinicaltrials.gov/api/v2/studies/NCT02306161?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
    supports: SUPPORT
    evidence_source: OTHER
    snippet: '{"protocolSection":{"identificationModule":{"nctId":"NCT02306161","briefTitle":"Combination Chemotherapy With or Without Ganitumab in Treating Patients With Newly Diagnosed Metastatic Ewing Sarcoma"},"statusModule":{"overallStatus":"ACTIVE_NOT_RECRUITING","completionDateStruct":{"date":"2026-09-17"},"lastUpdatePostDateStruct":{"date":"2026-07-29"}}}}'
    explanation: ClinicalTrials.gov structured registry fields retrieved on 2026-09-05 identify this trial and report ACTIVE_NOT_RECRUITING. This is administrative status, separate from the published efficacy results; the record also gives its last update and completion date.
- name: NCT02116777
  status: COMPLETED
  phase: PHASE_II
  description: >-
    ADVL1411 phase-I/II talazoparib-temozolomide trial. The phase-II Ewing cohort had no objective
    responses among ten patients; two had prolonged stable disease. This limits an unselected PARP-sensitivity
    treatment claim.
  notes: >-
    Registry status was checked on 2026-09-05. Published primary results do not imply
    that all follow-up is complete. The status is the current administrative registry
    value, not an efficacy conclusion.
  evidence:
  - reference: PMID:31724813
    reference_title: "Phase 1/2 trial of talazoparib in combination with temozolomide in children and adolescents with refractory/recurrent solid tumors including Ewing sarcoma: A Children's Oncology Group Phase 1 Consortium study (ADVL1411)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In phase 2, 0 of 10 EWS subjects experienced an objective response; two experienced prolonged SD."
    explanation: >-
      Clinical evidence supports feasibility but only partial therapeutic support because objective
      responses were not observed in the phase 2 Ewing cohort.
  - reference: url:https://clinicaltrials.gov/api/v2/studies/NCT02116777?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
    reference_title: https://clinicaltrials.gov/api/v2/studies/NCT02116777?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
    supports: SUPPORT
    evidence_source: OTHER
    snippet: '{"protocolSection":{"identificationModule":{"nctId":"NCT02116777","briefTitle":"Talazoparib and Temozolomide in Treating Younger Patients With Refractory or Recurrent Malignancies"},"statusModule":{"overallStatus":"COMPLETED","completionDateStruct":{"date":"2018-12-31"},"lastUpdatePostDateStruct":{"date":"2021-03-26"}}}}'
    explanation: ClinicalTrials.gov structured registry fields retrieved on 2026-09-05 identify this trial and report COMPLETED. This is administrative status, separate from the published efficacy results; the record also gives its last update and completion date.
- name: NCT02243605
  status: ACTIVE_NOT_RECRUITING
  phase: PHASE_II
  description: >-
    CABONE evaluated cabozantinib in advanced Ewing sarcoma and osteosarcoma in separate cohorts.
    The Ewing efficacy analysis included 39 patients; response rates should not be pooled across
    the two diseases.
  notes: >-
    Registry status was checked on 2026-09-05. Published primary results do not imply
    that all follow-up is complete. The status is the current administrative registry
    value, not an efficacy conclusion.
  evidence:
  - reference: PMID:32078813
    reference_title: "Cabozantinib in patients with advanced Ewing sarcoma or osteosarcoma (CABONE): a multicentre, single-arm, phase 2 trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: In patients with Ewing sarcoma, ten (26%; 95% CI 13-42) of 39 patients had an objective response (all partial responses) by 6 months
    explanation: >-
      Single-arm phase-II activity among efficacy-evaluable advanced Ewing patients, not proof of
      survival benefit or frontline efficacy.
  - reference: url:https://clinicaltrials.gov/api/v2/studies/NCT02243605?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
    reference_title: https://clinicaltrials.gov/api/v2/studies/NCT02243605?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
    supports: SUPPORT
    evidence_source: OTHER
    snippet: '{"protocolSection":{"identificationModule":{"nctId":"NCT02243605","briefTitle":"Cabozantinib S-malate in Treating Patients With Relapsed Osteosarcoma or Ewing Sarcoma"},"statusModule":{"overallStatus":"ACTIVE_NOT_RECRUITING","completionDateStruct":{"date":"2027-07-23"},"lastUpdatePostDateStruct":{"date":"2026-08-18"}}}}'
    explanation: ClinicalTrials.gov structured registry fields retrieved on 2026-09-05 identify this trial and report ACTIVE_NOT_RECRUITING. This is administrative status, separate from the published efficacy results; the record also gives its last update and completion date.
references:
- reference: PMID:11902298
  title: Fractures in pediatric Ewing sarcoma.
- reference: PMID:17177205
  title: "Chemotherapy response is an important predictor of local recurrence in Ewing sarcoma."
- reference: PMID:17250957
  title: "The Biology of Ewing sarcoma."
- reference: PMID:19289832
  title: EZH2 is a mediator of EWS/FLI1 driven tumor growth and metastasis blocking endothelial and neuro-ectodermal differentiation.
- reference: PMID:21559395
  title: "Modeling initiation of Ewing sarcoma in human neural crest cells."
- reference: PMID:22086061
  title: "Tumor-specific retargeting of an oncogenic transcription factor chimera results in dysregulation of chromatin and transcription."
- reference: PMID:22287547
  title: "PARP-1 inhibition as a targeted strategy to treat Ewing's sarcoma."
- reference: PMID:22749036
  title: EWS/FLI-responsive GGAA microsatellites exhibit polymorphic differences between European and African populations.
- reference: PMID:22959474
  title: "Characteristics and outcomes of patients with Ewing sarcoma over 40 years of age at diagnosis."
- reference: PMID:23091096
  title: "Randomized controlled trial of interval-compressed chemotherapy for the treatment of localized Ewing sarcoma: a report from the Children's Oncology Group."
- reference: PMID:23178492
  title: "Mechanism and relevance of EWS/FLI-mediated transcriptional repression in Ewing sarcoma."
- reference: PMID:25186949
  title: "The genomic landscape of pediatric Ewing sarcoma."
- reference: PMID:25223734
  title: "Genomic landscape of Ewing sarcoma defines an aggressive subtype with co-association of STAG2 and TP53 mutations."
- reference: PMID:25453903
  title: "EWS-FLI1 utilizes divergent chromatin remodeling mechanisms to directly activate or repress enhancer elements in Ewing sarcoma."
- reference: PMID:25691401
  title: "Diagnosis and treatment of Ewing sarcoma of the bone: a review article."
- reference: PMID:25779942
  title: "SLFN11 Is a Transcriptional Target of EWS-FLI1 and a Determinant of Drug Response in Ewing Sarcoma."
- reference: PMID:26000096
  title: "EWS/FLI utilizes NKX2-2 to repress mesenchymal features of Ewing sarcoma."
- reference: PMID:26214589
  title: "Chimeric EWSR1-FLI1 regulates the Ewing sarcoma susceptibility gene EGR2 via a GGAA microsatellite."
- reference: PMID:26240353
  title: "Flow perfusion effects on three-dimensional culture and drug sensitivity of Ewing sarcoma."
- reference: PMID:26505995
  title: "Combinations of PARP Inhibitors with Temozolomide Drive PARP1 Trapping and Apoptosis in Ewing's Sarcoma."
- reference: PMID:26929321
  title: "High-throughput small molecule screen identifies inhibitors of aberrant chromatin accessibility."
- reference: PMID:27923328
  title: "Modeling Stroma-Induced Drug Resistance in a Tissue-Engineered Tumor Model of Ewing Sarcoma."
- reference: PMID:28134926
  title: "DNA methylation heterogeneity defines a disease spectrum in Ewing sarcoma."
- reference: PMID:28844694
  title: "Cancer-Specific Retargeting of BAF Complexes by a Prion-like Domain."
- reference: PMID:29395061
  title: SLFN11 Blocks Stressed Replication Forks Independently of ATR.
- reference: PMID:29513652
  title: "EWS-FLI1 increases transcription to cause R-loops and block BRCA1 repair in Ewing sarcoma."
- reference: PMID:29867216
  title: "Distinct roles of cohesin-SA1 and cohesin-SA2 in 3D chromosome organization."
- reference: PMID:29873416
  title: "EWS-FLI1 reprograms the metabolism of Ewing sarcoma cells via positive regulation of glutamine import and serine-glycine biosynthesis."
- reference: PMID:30700749
  title: USP19 deubiquitinates EWS-FLI1 to regulate Ewing sarcoma growth.
- reference: PMID:30975996
  title: A requirement for STAG2 in replication fork progression creates a targetable synthetic lethality in cohesin-mutant cancers.
- reference: PMID:3113717
  title: "Small round blue cell sarcoma of bone mimicking atypical Ewing's sarcoma with neuroectodermal features. An analysis of five cases with immunohistochemical and electron microscopic support."
- reference: PMID:31724813
  title: "Phase 1/2 trial of talazoparib in combination with temozolomide in children and adolescents with refractory/recurrent solid tumors including Ewing sarcoma: A Children's Oncology Group Phase 1 Consortium study (ADVL1411)."
- reference: PMID:32049009
  title: "Transcriptional Programs Define Intratumoral Heterogeneity of Ewing Sarcoma at Single-Cell Resolution."
- reference: PMID:32078813
  title: "Cabozantinib in patients with advanced Ewing sarcoma or osteosarcoma (CABONE): a multicentre, single-arm, phase 2 trial."
- reference: PMID:32467316
  title: "STAG1 vulnerabilities for exploiting cohesin synthetic lethality in STAG2-deficient cancers."
- reference: PMID:33080033
  title: "EWS-FLI1 regulates and cooperates with core regulatory circuitry in Ewing sarcoma."
- reference: PMID:33741715
  title: "EWS-FLI1 and Menin Converge to Regulate ATF4 Activity in Ewing Sarcoma."
- reference: PMID:33818887
  title: "Ewing sarcoma."
- reference: PMID:34129824
  title: "STAG2 loss rewires oncogenic and developmental programs to promote metastasis in Ewing sarcoma."
- reference: PMID:34235109
  title: "Outcomes of Adult Ewing Sarcoma Treated with Multimodality Therapy: A Single-Institute Experience."
- reference: PMID:34329586
  title: TRIM8 modulates the EWS/FLI oncoprotein to promote survival in Ewing sarcoma.
- reference: PMID:34453478
  title: "In vivo evaluation of the lysine-specific demethylase (KDM1A/LSD1) inhibitor SP-2577 (Seclidemstat) against pediatric sarcoma preclinical models: A report from the Pediatric Preclinical Testing Consortium (PPTC)."
- reference: PMID:34485689
  title: "Educational Case: Ewing Sarcoma of Bone."
- reference: PMID:35483357
  title: "Tuning levels of low-complexity domain interactions to modulate endogenous oncogenic transcription."
- reference: PMID:35653119
  title: "EWS::FLI1 and HOXD13 Control Tumor Cell Plasticity in Ewing Sarcoma."
- reference: PMID:36221002
  title: "Adverse prognostic impact of the loss of STAG2 protein expression in patients with newly diagnosed localised Ewing sarcoma: A report from the Children's Oncology Group."
- reference: PMID:36522207
  title: "Comparison of two chemotherapy regimens in patients with newly diagnosed Ewing sarcoma (EE2012): an open-label, randomised, phase 3 trial."
- reference: PMID:36658219
  title: "ETV6 dependency in Ewing sarcoma by antagonism of EWS-FLI1-mediated enhancer activation."
- reference: PMID:36669140
  title: "Randomized Phase III Trial of Ganitumab With Interval-Compressed Chemotherapy for Patients With Newly Diagnosed Metastatic Ewing Sarcoma: A Report From the Children's Oncology Group."
- reference: PMID:36787739
  title: "Targeted long-read sequencing of the Ewing sarcoma 6p25.1 susceptibility locus identifies germline-somatic interactions with EWSR1-FLI1 binding."
- reference: PMID:37279093
  title: A Bifunctional PARP-HDAC Inhibitor with Activity in Ewing Sarcoma.
- reference: PMID:37471463
  title: Cancer-Associated Fibroblast-Like Tumor Cells Remodel the Ewing Sarcoma Tumor Microenvironment.
- reference: PMID:37478161
  title: "USP1 Expression Driven by EWS::FLI1 Transcription Factor Stabilizes Survivin and Mitigates Replication Stress in Ewing Sarcoma."
- reference: PMID:37963210
  title: The Chromatin Remodeler CHD4 Sustains Ewing Sarcoma Cell Survival by Controlling Global Chromatin Architecture.
- reference: PMID:39158802
  title: Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
- reference: PMID:39487368
  title: "STAG2 loss in Ewing sarcoma alters enhancer-promoter contacts dependent and independent of EWS::FLI1."
- reference: PMID:40080499
  title: "YAP1 is a key regulator of EWS::FLI1-dependent malignant transformation upon IGF-1-mediated reprogramming of bone mesenchymal stem cells."
- reference: PMID:40215343
  title: "(GGAA)(3)-Based TF-PROTACs Enable Targeted Degradation of ETV6 to Inhibit Ewing Sarcoma Growth."
- reference: PMID:40568108
  title: Disruption of Microhomology-mediated End-joining in Ewing Sarcoma.
- reference: PMID:40667384
  title: Multimodal single-cell analyses reveal distinct fusion-regulated transcriptional programs in Ewing sarcoma.
- reference: PMID:40721661
  title: "EWS::FLI1-DHX9 interaction promotes Ewing sarcoma sensitivity to DNA topoisomerase 1 poisons by altering R-loop metabolism."
- reference: PMID:40852926
  title: "Seclidemstat (SP-2577) Induces Transcriptomic Reprogramming and Cytotoxicity in Multiple Fusion-Positive Sarcomas."
- reference: PMID:40911901
  title: "Advancing Preclinical Biology for Ewing Sarcoma: An International Effort."
- reference: PMID:41072418
  title: Origin of Ewing sarcoma by embryonic reprogramming of neural crest to mesoderm.
- reference: PMID:41136396
  title: "EWS::FLI1 expression in human embryonic mesenchymal stem cells leads to transcriptional reprograming, defective DNA damage repair and Ewing sarcoma."
- reference: PMID:41206913
  title: "Analysis of comprehensive genomic profiling test for Ewing sarcoma in pediatric patients and adults using the nationwide clinical and genomic database in Japan."
- reference: PMID:41484205
  title: "Modelling EWS::FLI1 protein fluctuations reveal determinants of tumor plasticity in Ewing sarcoma."
- reference: PMID:41591981
  title: "Phase I/II Study of the PARP Inhibitor Olaparib and Irinotecan in Children and Young Adults with Recurrent/Refractory Malignancies: Arm D of the AcSé-ESMART Trial."
- reference: PMID:41620417
  title: Targeting glycerophospholipid biosynthesis overcomes chemoresistance driven by SLFN11 loss in Ewing sarcoma.
- reference: PMID:41659683
  title: "Dynamic regulation of endogenous transcription factor hubs at single-molecule resolution."
- reference: PMID:41681984
  title: "Characterisation of Bespoke Patient-Derived In Vitro Models of Ewing Sarcoma."
- reference: PMID:41832299
  title: "Addition of zoledronic acid to consolidation chemotherapy in Ewing sarcoma-EURO EWING 2012 (EE2012): an international, open-label, randomised controlled phase III trial."
- reference: PMID:41950086
  title: "STAG2 loss amplifies EWS-FLI1-driven microsatellite enhancer activity promoting Ewing sarcoma aggressiveness."
- reference: url:https://clinicaltrials.gov/api/v2/studies/NCT00006734?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
  title: https://clinicaltrials.gov/api/v2/studies/NCT00006734?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
- reference: url:https://clinicaltrials.gov/api/v2/studies/NCT02306161?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
  title: https://clinicaltrials.gov/api/v2/studies/NCT02306161?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
- reference: url:https://clinicaltrials.gov/api/v2/studies/NCT02116777?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
  title: https://clinicaltrials.gov/api/v2/studies/NCT02116777?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
- reference: url:https://clinicaltrials.gov/api/v2/studies/NCT02243605?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
  title: https://clinicaltrials.gov/api/v2/studies/NCT02243605?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
- reference: ICTRP:ISRCTN92192408
  title: Euro Ewing 2012
- reference: ICTRP:ISRCTN54540667
  title: Paramedic Initiated Lisinopril For Acute Stroke
updated_date: '2026-09-05T11:53:11Z'
📚

References & Deep Research

References

79
PMID:11902298
Fractures in pediatric Ewing sarcoma.
No top-level findings curated for this source.
PMID:17177205
Chemotherapy response is an important predictor of local recurrence in Ewing sarcoma.
No top-level findings curated for this source.
PMID:17250957
The Biology of Ewing sarcoma.
No top-level findings curated for this source.
PMID:19289832
EZH2 is a mediator of EWS/FLI1 driven tumor growth and metastasis blocking endothelial and neuro-ectodermal differentiation.
No top-level findings curated for this source.
PMID:21559395
Modeling initiation of Ewing sarcoma in human neural crest cells.
No top-level findings curated for this source.
PMID:22086061
Tumor-specific retargeting of an oncogenic transcription factor chimera results in dysregulation of chromatin and transcription.
No top-level findings curated for this source.
PMID:22287547
PARP-1 inhibition as a targeted strategy to treat Ewing's sarcoma.
No top-level findings curated for this source.
PMID:22749036
EWS/FLI-responsive GGAA microsatellites exhibit polymorphic differences between European and African populations.
No top-level findings curated for this source.
PMID:22959474
Characteristics and outcomes of patients with Ewing sarcoma over 40 years of age at diagnosis.
No top-level findings curated for this source.
PMID:23091096
Randomized controlled trial of interval-compressed chemotherapy for the treatment of localized Ewing sarcoma: a report from the Children's Oncology Group.
No top-level findings curated for this source.
PMID:23178492
Mechanism and relevance of EWS/FLI-mediated transcriptional repression in Ewing sarcoma.
No top-level findings curated for this source.
PMID:25186949
The genomic landscape of pediatric Ewing sarcoma.
No top-level findings curated for this source.
PMID:25223734
Genomic landscape of Ewing sarcoma defines an aggressive subtype with co-association of STAG2 and TP53 mutations.
No top-level findings curated for this source.
PMID:25453903
EWS-FLI1 utilizes divergent chromatin remodeling mechanisms to directly activate or repress enhancer elements in Ewing sarcoma.
No top-level findings curated for this source.
PMID:25691401
Diagnosis and treatment of Ewing sarcoma of the bone: a review article.
No top-level findings curated for this source.
PMID:25779942
SLFN11 Is a Transcriptional Target of EWS-FLI1 and a Determinant of Drug Response in Ewing Sarcoma.
No top-level findings curated for this source.
PMID:26000096
EWS/FLI utilizes NKX2-2 to repress mesenchymal features of Ewing sarcoma.
No top-level findings curated for this source.
PMID:26214589
Chimeric EWSR1-FLI1 regulates the Ewing sarcoma susceptibility gene EGR2 via a GGAA microsatellite.
No top-level findings curated for this source.
PMID:26240353
Flow perfusion effects on three-dimensional culture and drug sensitivity of Ewing sarcoma.
No top-level findings curated for this source.
PMID:26505995
Combinations of PARP Inhibitors with Temozolomide Drive PARP1 Trapping and Apoptosis in Ewing's Sarcoma.
No top-level findings curated for this source.
PMID:26929321
High-throughput small molecule screen identifies inhibitors of aberrant chromatin accessibility.
No top-level findings curated for this source.
PMID:27923328
Modeling Stroma-Induced Drug Resistance in a Tissue-Engineered Tumor Model of Ewing Sarcoma.
No top-level findings curated for this source.
PMID:28134926
DNA methylation heterogeneity defines a disease spectrum in Ewing sarcoma.
No top-level findings curated for this source.
PMID:28844694
Cancer-Specific Retargeting of BAF Complexes by a Prion-like Domain.
No top-level findings curated for this source.
PMID:29395061
SLFN11 Blocks Stressed Replication Forks Independently of ATR.
No top-level findings curated for this source.
PMID:29513652
EWS-FLI1 increases transcription to cause R-loops and block BRCA1 repair in Ewing sarcoma.
No top-level findings curated for this source.
PMID:29867216
Distinct roles of cohesin-SA1 and cohesin-SA2 in 3D chromosome organization.
No top-level findings curated for this source.
PMID:29873416
EWS-FLI1 reprograms the metabolism of Ewing sarcoma cells via positive regulation of glutamine import and serine-glycine biosynthesis.
No top-level findings curated for this source.
PMID:30700749
USP19 deubiquitinates EWS-FLI1 to regulate Ewing sarcoma growth.
No top-level findings curated for this source.
PMID:30975996
A requirement for STAG2 in replication fork progression creates a targetable synthetic lethality in cohesin-mutant cancers.
No top-level findings curated for this source.
PMID:3113717
Small round blue cell sarcoma of bone mimicking atypical Ewing's sarcoma with neuroectodermal features. An analysis of five cases with immunohistochemical and electron microscopic support.
No top-level findings curated for this source.
PMID:31724813
Phase 1/2 trial of talazoparib in combination with temozolomide in children and adolescents with refractory/recurrent solid tumors including Ewing sarcoma: A Children's Oncology Group Phase 1 Consortium study (ADVL1411).
No top-level findings curated for this source.
PMID:32049009
Transcriptional Programs Define Intratumoral Heterogeneity of Ewing Sarcoma at Single-Cell Resolution.
No top-level findings curated for this source.
PMID:32078813
Cabozantinib in patients with advanced Ewing sarcoma or osteosarcoma (CABONE): a multicentre, single-arm, phase 2 trial.
No top-level findings curated for this source.
PMID:32467316
STAG1 vulnerabilities for exploiting cohesin synthetic lethality in STAG2-deficient cancers.
No top-level findings curated for this source.
PMID:33080033
EWS-FLI1 regulates and cooperates with core regulatory circuitry in Ewing sarcoma.
No top-level findings curated for this source.
PMID:33741715
EWS-FLI1 and Menin Converge to Regulate ATF4 Activity in Ewing Sarcoma.
No top-level findings curated for this source.
PMID:33818887
Ewing sarcoma.
No top-level findings curated for this source.
PMID:34129824
STAG2 loss rewires oncogenic and developmental programs to promote metastasis in Ewing sarcoma.
No top-level findings curated for this source.
PMID:34235109
Outcomes of Adult Ewing Sarcoma Treated with Multimodality Therapy: A Single-Institute Experience.
No top-level findings curated for this source.
PMID:34329586
TRIM8 modulates the EWS/FLI oncoprotein to promote survival in Ewing sarcoma.
No top-level findings curated for this source.
PMID:34453478
In vivo evaluation of the lysine-specific demethylase (KDM1A/LSD1) inhibitor SP-2577 (Seclidemstat) against pediatric sarcoma preclinical models: A report from the Pediatric Preclinical Testing Consortium (PPTC).
No top-level findings curated for this source.
PMID:34485689
Educational Case: Ewing Sarcoma of Bone.
No top-level findings curated for this source.
PMID:35483357
Tuning levels of low-complexity domain interactions to modulate endogenous oncogenic transcription.
No top-level findings curated for this source.
PMID:35653119
EWS::FLI1 and HOXD13 Control Tumor Cell Plasticity in Ewing Sarcoma.
No top-level findings curated for this source.
PMID:36221002
Adverse prognostic impact of the loss of STAG2 protein expression in patients with newly diagnosed localised Ewing sarcoma: A report from the Children's Oncology Group.
No top-level findings curated for this source.
PMID:36522207
Comparison of two chemotherapy regimens in patients with newly diagnosed Ewing sarcoma (EE2012): an open-label, randomised, phase 3 trial.
No top-level findings curated for this source.
PMID:36658219
ETV6 dependency in Ewing sarcoma by antagonism of EWS-FLI1-mediated enhancer activation.
No top-level findings curated for this source.
PMID:36669140
Randomized Phase III Trial of Ganitumab With Interval-Compressed Chemotherapy for Patients With Newly Diagnosed Metastatic Ewing Sarcoma: A Report From the Children's Oncology Group.
No top-level findings curated for this source.
PMID:36787739
Targeted long-read sequencing of the Ewing sarcoma 6p25.1 susceptibility locus identifies germline-somatic interactions with EWSR1-FLI1 binding.
No top-level findings curated for this source.
PMID:37279093
A Bifunctional PARP-HDAC Inhibitor with Activity in Ewing Sarcoma.
No top-level findings curated for this source.
PMID:37471463
Cancer-Associated Fibroblast-Like Tumor Cells Remodel the Ewing Sarcoma Tumor Microenvironment.
No top-level findings curated for this source.
PMID:37478161
USP1 Expression Driven by EWS::FLI1 Transcription Factor Stabilizes Survivin and Mitigates Replication Stress in Ewing Sarcoma.
No top-level findings curated for this source.
PMID:37963210
The Chromatin Remodeler CHD4 Sustains Ewing Sarcoma Cell Survival by Controlling Global Chromatin Architecture.
No top-level findings curated for this source.
PMID:39158802
Clinical practice guidelines for the treatment of Ewing sarcoma (Spanish Sarcoma Research Group-GEIS).
No top-level findings curated for this source.
PMID:39487368
STAG2 loss in Ewing sarcoma alters enhancer-promoter contacts dependent and independent of EWS::FLI1.
No top-level findings curated for this source.
PMID:40080499
YAP1 is a key regulator of EWS::FLI1-dependent malignant transformation upon IGF-1-mediated reprogramming of bone mesenchymal stem cells.
No top-level findings curated for this source.
PMID:40215343
(GGAA)(3)-Based TF-PROTACs Enable Targeted Degradation of ETV6 to Inhibit Ewing Sarcoma Growth.
No top-level findings curated for this source.
PMID:40568108
Disruption of Microhomology-mediated End-joining in Ewing Sarcoma.
No top-level findings curated for this source.
PMID:40667384
Multimodal single-cell analyses reveal distinct fusion-regulated transcriptional programs in Ewing sarcoma.
No top-level findings curated for this source.
PMID:40721661
EWS::FLI1-DHX9 interaction promotes Ewing sarcoma sensitivity to DNA topoisomerase 1 poisons by altering R-loop metabolism.
No top-level findings curated for this source.
PMID:40852926
Seclidemstat (SP-2577) Induces Transcriptomic Reprogramming and Cytotoxicity in Multiple Fusion-Positive Sarcomas.
No top-level findings curated for this source.
PMID:40911901
Advancing Preclinical Biology for Ewing Sarcoma: An International Effort.
No top-level findings curated for this source.
PMID:41072418
Origin of Ewing sarcoma by embryonic reprogramming of neural crest to mesoderm.
No top-level findings curated for this source.
PMID:41136396
EWS::FLI1 expression in human embryonic mesenchymal stem cells leads to transcriptional reprograming, defective DNA damage repair and Ewing sarcoma.
No top-level findings curated for this source.
PMID:41206913
Analysis of comprehensive genomic profiling test for Ewing sarcoma in pediatric patients and adults using the nationwide clinical and genomic database in Japan.
No top-level findings curated for this source.
PMID:41484205
Modelling EWS::FLI1 protein fluctuations reveal determinants of tumor plasticity in Ewing sarcoma.
No top-level findings curated for this source.
PMID:41591981
Phase I/II Study of the PARP Inhibitor Olaparib and Irinotecan in Children and Young Adults with Recurrent/Refractory Malignancies: Arm D of the AcSé-ESMART Trial.
No top-level findings curated for this source.
PMID:41620417
Targeting glycerophospholipid biosynthesis overcomes chemoresistance driven by SLFN11 loss in Ewing sarcoma.
No top-level findings curated for this source.
PMID:41659683
Dynamic regulation of endogenous transcription factor hubs at single-molecule resolution.
No top-level findings curated for this source.
PMID:41681984
Characterisation of Bespoke Patient-Derived In Vitro Models of Ewing Sarcoma.
No top-level findings curated for this source.
PMID:41832299
Addition of zoledronic acid to consolidation chemotherapy in Ewing sarcoma-EURO EWING 2012 (EE2012): an international, open-label, randomised controlled phase III trial.
No top-level findings curated for this source.
PMID:41950086
STAG2 loss amplifies EWS-FLI1-driven microsatellite enhancer activity promoting Ewing sarcoma aggressiveness.
No top-level findings curated for this source.
url:https://clinicaltrials.gov/api/v2/studies/NCT00006734?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
https://clinicaltrials.gov/api/v2/studies/NCT00006734?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
No top-level findings curated for this source.
url:https://clinicaltrials.gov/api/v2/studies/NCT02306161?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
https://clinicaltrials.gov/api/v2/studies/NCT02306161?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
No top-level findings curated for this source.
url:https://clinicaltrials.gov/api/v2/studies/NCT02116777?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
https://clinicaltrials.gov/api/v2/studies/NCT02116777?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
No top-level findings curated for this source.
url:https://clinicaltrials.gov/api/v2/studies/NCT02243605?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
https://clinicaltrials.gov/api/v2/studies/NCT02243605?fields=NCTId,BriefTitle,OverallStatus,LastUpdatePostDate,CompletionDate
No top-level findings curated for this source.
ICTRP:ISRCTN92192408
Euro Ewing 2012
No top-level findings curated for this source.
ICTRP:ISRCTN54540667
Paramedic Initiated Lisinopril For Acute Stroke
No top-level findings curated for this source.

Deep Research

2

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Evaluations and curation notes (1)

Review Ewing sarcoma mechanisms, clinical scope and four OpenScientist reports · 2026-09-04T22:33:31Z · View source

Review scope and inputs - Read the entire Ewing_Sarcoma disease YAML and all four OpenScientist reports with citation sidecars (canonical fusion enhanceropathy, cell of origin, replication stress, cohesin high-risk modifier). - Read both broad deep-research artifacts and the Falcon citation sidecar. Falcon supports major fusion/chromatin/metabolic/clinical themes; its phenotype frequencies and ontology candidates were not accepted without primary verification. The cyberian-codex file is a short local placeholder synthesis, not independent substantive deep research. - Independently fetched and examined high-value mechanistic, human-cohort, clinical-trial and guideline sources. No provider computational bundle, dataset export or executed analysis was available. No new experimental or raw-data reanalysis is claimed. Content-completeness checklist 1. Phenotypes: corrected adult-cohort scope for pain and swelling; removed unsupported symptom frequency bands; separated presentation metastasis, three-year EFS and five-year OS; distinguished disease-related and post-treatment fracture. Supported fever/weight loss from the general clinical discussion of a didactic article, not its fictional case. Added a local bone-destruction mechanism connecting osseous growth to pain/fracture. 2. Subtypes: retained ontology-bound osseous/extraskeletal presentations; distinguished FET-ETS Ewing sarcoma from CIC/BCOR/EWSR1-non-ETS sarcomas. Removed automatic generalization of all detailed EWSR1-FLI1 results to every rare fusion partner. Rare FUS fusions are included in the definition. 3. Pathophysiology: separated hub dynamics from protein dosage; NuRD/LSD1 repression from CHD4 architecture maintenance; transcription-associated R-loops, BRCA1 availability, DHX9 under TOP1 stress, SLFN11 fork arrest and USP1-survivin buffering. Added provisional POLQ/MMEJ splicing, SLFN11-loss lipid remodeling, PARP1-supported transcription, IL-6/STAT3 stroma signaling, hybrid matrix-producing tumor states, EZH2 differentiation repression and HOXD13 plasticity. Removed enhancer-to-STAG2-loss, enhancer-to-ETV6 and permissive-cell-to-fusion arrows. Did not invent edges to force strong connectivity. Broader-cancer STAG2/HR evidence is a research gap rather than a confirmed Ewing edge. 4. Treatment/trials: retained multimodal chemotherapy/local control, added randomized interval-compression and EE2012 evidence, five trial records, advanced-disease cabozantinib activity, negative ganitumab and 2026 zoledronic-acid results, and limited later olaparib-irinotecan activity. Separated dual PARP-HDAC pharmacology from talazoparib-temozolomide, removed unsupported direct CHD4 targeting, and redirected USP1 inhibition to its survival buffer. Preclinical targets are not called proven treatments. No unverified current trial recruitment status was asserted. 5. Genetics: retained acquired fusion and recurrent STAG2/TP53/CDKN2A alterations; distinguished IHC protein loss from sequence mutation and CDKN2A deletion from point mutation. Human germline susceptibility is locus-specific, not Mendelian penetrance. BARD1 model evidence does not imply a 10% BARD1 frequency. 6. Diagnostics/biomarkers: added integrated biopsy, immunophenotype and genetic confirmation; CD99/NKX2.2 specificity limits; imaging and marrow-staging scope; localized/metastatic/relapsed stages. Corrected high-grade evidence and described necrosis as post-chemotherapy response rather than a universal presenting morphology. 7. References: replaced numerous non-propositional truncated snippets with individually inspected complete source statements; all new/modified titles come from generated reference-cache frontmatter. Prior source snippets falsely conflating neuroectodermal origin or observational surgery benefit were replaced. Source quotes and structured evidence types retain clinical, experimental and review distinctions. 8. Overall consumption: the central supported themes across all four reports and broad research are represented. Peripheral untested therapeutic combinations, exhaustive database absences, unsupported causal independence, speculative SIX1/STAG2 links and ontology candidates are assessed or kept as research questions rather than asserted as established edges. 9. Models/datasets: separated neural-crest-targeted zebrafish and human-MSC xenograft validation from non-animal cultures; removed the unsupported flow-bioreactor-to-developmental-YAP edge and OrganOnChip classification. Existing catalog datasets remain metadata records, not claimed independently accessed patient data. The frozen accession blob was never read, written or staged. Report assessment findings - Four authoritative codex assessment YAMLs contain 55 claim dispositions and 24 reported/proposed analysis inventories. Future tests are SKIPPED. Claimed cBioPortal and knowledge-graph analyses are REPORTED_ONLY/UNVERIFIABLE without artifacts. Negative database/registry searches are UNVERIFIABLE. - Reject the reversed NR0B1 ancestry claim and added unstudied Asian population; African subjects had longer NR0B1 repeats in PMID:22749036. Different COG IHC/EFS and Japanese profiling mutation/OS cohorts do not establish ancestry-specific prognostic biology. - Reject cBioPortal point-mutation mutual exclusivity as confirmation of CDKN2A deletion exclusivity, and do not treat publication-derived portal cohorts as independent biological validation. - Reject the report BARD1 ~10% attribution; the source refers to variants across many DNA-repair genes. Reject IHC protein loss as proof of epigenetic silencing. - Qualify two unflagged preprints (endogenous hubs, POLQ/MMEJ), developmental IGF-1/YAP1 in mouse cells, zebrafish versus human lineage, partial fusion depletion versus patient drug outcomes, and complete independence of DHX9 sequestration from transcription. - Correct YAP1 transcriptional opposition versus tumor suppression, and the assumption that all permissive GGAA sites must already be open before fusion expression. The fusion is a pioneer factor. Validation - just validate-disorders kb/disorders/Ewing_Sarcoma.yaml passed schema, ontology-term and no-full-text reference validation: 188/188 evidence snippets verified. - All four assessment files passed both LinkML schema validation and report quote/path/provenance-link validation. - Targeted duplicate-key, enum, entity-reference, causal-target, qualifier-term, source-defect and snippet-boundary checks passed. - Single-disease HTML render succeeded; generated page is not part of the curation commit. - Falcon named-entity preflight warned because FLI1 is mentioned as often as EWSR1; these are the two partners of the disease-defining fusion, so this is not evidence of entity confusion. The review separately checked Ewing versus non-Ewing round-cell sarcoma scope. - Reference-title, snippet-grading (after correcting one review article classification), folded-hyphen, cache-order, term-cache-integrity and reference-cache-frontmatter gates passed. Causal graph construction produced 57 nodes and 63 edges without orphan targets or integrity issues; a static graph was visually inspected. No human clinical efficacy or reproducible provider computation is inferred from schema validation.

Disorder ▸

Disorder

  • Name: Ewing Sarcoma
  • Category:
  • Existing deep-research providers: falcon
  • Existing evidence reference count in YAML: 5

Key Pathophysiology Nodes

  • EWS-FLI1 Fusion Oncogene
  • Aberrant Transcriptional Regulation
  • Blocked Differentiation
  • Deep research literature mapping

Citation Inventory (for evidence mapping)

  • DOI:10.1158/1541-7786.mcr-20-0679
  • DOI:10.3389/fonc.2024.1388484
Falcon ▸
Disease Pathophysiology Research Report
Edison Scientific Literature 13 citations 2026-01-24T13:40:49.760866

Disease Pathophysiology Research Report

Target Disease - Disease Name: Ewing Sarcoma - MONDO ID: — - Category: Malignant small round cell tumor of bone/soft tissue

Pathophysiology description Ewing sarcoma (EwS) is defined by pathognomonic FET–ETS gene fusions, most commonly EWSR1::FLI1 generated by t(11;22)(q24;q12), with recurrent junction types (EWSR1 exon 7 to FLI1 exon 6 [type I] or exon 5 [type II]) (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). The fusion encodes a potent aberrant transcription factor that couples the low-complexity transactivation domain of EWSR1 to the ETS DNA-binding domain of FLI1; both halves are necessary for oncogenic activity, yet transformation efficiency depends on permissive cellular context (jimenez2024anepigeneticapproacha pages 21-24). EwS tumors are genomically “quiet” by point mutation burden (approximately 0.15–0.45 mutations/Mb) but display recurrent copy-number changes (e.g., gains of 8, 2, 1q; loss of 16q) and focal 9p loss with CDKN2A deletion; recurrent secondary alterations include STAG2 (~20%) and TP53 (5–20%), with adverse impact especially when co-mutated (jimenez2024anepigeneticapproachb pages 21-24, jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24).

At the chromatin level, EWSR1::FLI1 drives extensive enhancer reprogramming. The fusion binds canonical ETS motifs and uniquely occupies tandem GGAA microsatellite “super-enhancers,” creating de novo regulatory elements and activating lineage-inappropriate targets (e.g., NR0B1/DAX1); as summarized, the protein “binds tandem GGAA microsatellite repeats” to amplify transcriptional output beyond wild-type FLI1 (petrescu2024preclinicalmodelsfor pages 3-5). This enhanceropathy couples to transcriptional stress, R-loop formation, and replication stress, which engages ATR pathways and creates vulnerabilities to DNA damage response (DDR) agents such as PARP inhibitors (petrescu2024preclinicalmodelsfor pages 3-5). EWSR1::FLI1 also directly and indirectly remodels metabolic programs. It binds the ATF4 promoter and elevates ATF4, a master regulator of the serine biosynthesis pathway (SSP), while the scaffold protein menin is additionally required to sustain ATF4 and the broader ATF4-dependent transcriptome; inhibiting either EWSR1::FLI1 or menin reduces ATF4 and SSP enzymes (e.g., PHGDH) (jimenez2021ewsfli1andmenin pages 1-3).

Clinically, EwS presents as undifferentiated small round blue cell tumors, typically with strong membranous CD99 expression; outcomes are good for localized disease with dose-compressed chemotherapy but remain poor for metastatic/recurrent disease. A position summary reports five-year event-free survival (EFS) around 87% for localized disease and approximately 38% three-year EFS for recurrent/metastatic disease, with relapse driven by resistant clones (jimenez2024anepigeneticapproach pages 21-24). Trials targeting IGF1R and mTOR have shown limited yet notable activity in subsets, reflecting frequent IGF axis engagement in EwS biology (jimenez2024anepigeneticapproach pages 21-24).

Key concepts and definitions with current understanding - Initiating lesion: Balanced translocation producing EWSR1::FLI1 (or other FET–ETS fusions), often exon 7 of EWSR1 fused to exon 6 (type I) or exon 5 (type II) of FLI1 (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). URL: https://doi.org/ (as cited within 2024 thesis); publication year 2024 (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). - Chromatin enhanceropathy: EWSR1::FLI1 binds canonical ETS sites and GGAA microsatellites to establish de novo enhancers and high-output transcriptional programs (“binds tandem GGAA microsatellite repeats”) (petrescu2024preclinicalmodelsfor pages 3-5). URL: https://doi.org/10.3389/fonc.2024.1388484; publication date Jul 2024 (petrescu2024preclinicalmodelsfor pages 3-5). - Genomic landscape: Low SNV burden (0.15–0.45/Mb), recurrent CNAs (chr8, chr2, 1q gains; 16q loss), and TP53/STAG2 alterations with prognostic interaction (jimenez2024anepigeneticapproachb pages 21-24, jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). Publication year 2024 (jimenez2024anepigeneticapproachb pages 21-24, jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). - Metabolic rewiring: EWSR1::FLI1 and menin converge on ATF4 to upregulate serine biosynthesis; ATF4 is directly activated by EWSR1::FLI1 binding to its promoter (jimenez2021ewsfli1andmenin pages 1-3). URL: https://doi.org/10.1158/1541-7786.mcr-20-0679; publication date Mar 2021 (jimenez2021ewsfli1andmenin pages 1-3). - Diagnostic phenotype: Small round blue cell tumor with strong CD99; fusion is disease-defining (petrescu2024preclinicalmodelsfor pages 3-5, jimenez2024anepigeneticapproacha pages 21-24). URL: https://doi.org/10.3389/fonc.2024.1388484; publication date Jul 2024 (petrescu2024preclinicalmodelsfor pages 3-5).

Recent developments and latest research (2023–2024 priority) - 2024 epigenetics-focused synthesis: Updated compendium of EwS fusion biology, genomic landscape, and epigenetic targets, reiterating dominant EWSR1::FLI1 fusion types, low point-mutation burden, recurrent CNAs, and the need for epigenetic/DDR-targeted strategies (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). Publication year 2024. - 2024 preclinical models review: Emphasizes EWSR1::FLI1 enhancer rewiring at GGAA microsatellites, R-loop–associated genomic instability, and associated sensitivity to DDR targeting, integrating model systems that recapitulate these features (petrescu2024preclinicalmodelsfor pages 3-5). URL: https://doi.org/10.3389/fonc.2024.1388484; Jul 2024.

Current applications and real-world implementations - Molecular diagnosis: Detection of EWSR1::FLI1 (or alternate FET–ETS) fusion is the defining diagnostic test; morphology and CD99 support the diagnosis (petrescu2024preclinicalmodelsfor pages 3-5, jimenez2024anepigeneticapproacha pages 21-24). Jul 2024; 2024. - Systemic therapy: Standard dose-compressed chemotherapy achieves high EFS in localized disease; investigational/adjunct approaches include IGF1R antibodies and mTOR inhibitors, with limited success and need for biomarker-driven selection (jimenez2024anepigeneticapproach pages 21-24). Publication year 2024. - Emerging therapeutic rationale: DDR targeting (e.g., PARP inhibitors) leverages EWSR1::FLI1-induced transcriptional/replication stress and R-loops (petrescu2024preclinicalmodelsfor pages 3-5). Jul 2024.

Expert opinions and analysis from authoritative sources - Fusion-centric disease model: Contemporary synthesis underscores that the EWSR1::FLI1 chimeric transcription factor is the primary oncogenic driver, with cellular context determining permissiveness for transformation; ectopic fusion expression alone “often fails to recapitulate transformation,” arguing for a developmental window/cell-of-origin constraint (jimenez2024anepigeneticapproacha pages 21-24). 2024. - Enhancer rewiring as core pathophysiology: The capacity of EWSR1::FLI1 to create de novo enhancers at GGAA microsatellites is a unifying explanation for widespread transcriptional dysregulation and downstream vulnerabilities (petrescu2024preclinicalmodelsfor pages 3-5). 2024. - Metabolic dependency via ATF4: Menin and EWSR1::FLI1 co-regulate ATF4, sustaining serine biosynthesis; this axis links oncogenic transcription to metabolic plasticity and may yield therapeutic windows (jimenez2021ewsfli1andmenin pages 1-3). 2021.

Relevant statistics and data from recent studies - Mutation burden: ~0.15–0.45 mutations/Mb (jimenez2024anepigeneticapproachb pages 21-24, jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). 2024. - Fusion junction frequencies: EWSR1 exon 7 to FLI1 exon 6 (~60%, type I) and exon 5 (~25%, type II) (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). 2024. - Secondary alterations: STAG2 ~20%; TP53 5–20% (jimenez2024anepigeneticapproachb pages 21-24, jimenez2024anepigeneticapproacha pages 21-24). 2024. - Outcomes: Five-year EFS ~87% for localized disease; ~38% three-year EFS for metastatic/recurrent (jimenez2024anepigeneticapproach pages 21-24). 2024.

Structured knowledge for ontology/annotation - Key molecular players (HGNC): EWSR1 (EWSR1::FLI1 fusion; HGNC:3508), FLI1 (HGNC:3749), TP53 (HGNC:11998), STAG2 (HGNC:11354), CDKN2A (HGNC:1787), ATF4 (HGNC:792), PHGDH (HGNC:8922), MEN1 (menin; HGNC:7010) (jimenez2024anepigeneticapproacha pages 21-24, jimenez2021ewsfli1andmenin pages 1-3, jimenez2024anepigeneticapproach pages 21-24). Where directly supported: EWSR1, FLI1, TP53, STAG2, CDKN2A (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24); ATF4/PHGDH/MEN1 (jimenez2021ewsfli1andmenin pages 1-3). - Biological processes (GO examples, aligned to evidence): - Regulation of transcription by RNA polymerase II; enhancer activation/de novo enhancer formation at GGAA microsatellites (petrescu2024preclinicalmodelsfor pages 3-5). - Response to endoplasmic reticulum stress and amino acid biosynthetic process (serine biosynthesis) via ATF4 (jimenez2021ewsfli1andmenin pages 1-3). - DNA replication stress and DNA repair signaling engagement (linked to R-loops/ATR vulnerability) (petrescu2024preclinicalmodelsfor pages 3-5). - Cellular components: Chromatin, enhancers/super-enhancers (GGAA microsatellite-associated), nucleoplasm; cell membrane (CD99 immunophenotype) (petrescu2024preclinicalmodelsfor pages 3-5). - Cell types (CL terms): Primitive mesenchymal progenitors/neural crest–related progenitors implicated as permissive cells of origin; tumor cells are undifferentiated small round cells (petrescu2024preclinicalmodelsfor pages 3-5, jimenez2021ewsfli1andmenin pages 1-3). 2024; 2021. - Anatomical locations (UBERON): Long bones, pelvis, axial skeleton (general clinical domain, consistent with EwS bone/soft tissue presentation; diagnostic phenotype summarized in review) (petrescu2024preclinicalmodelsfor pages 3-5). - Chemical entities (CHEBI): Not specifically evidenced in the extracted items beyond general references to chemotherapy and targeted agents; IGF1R/mTOR targeted agents noted (jimenez2024anepigeneticapproach pages 21-24).

Detailed sections 1) Core Pathophysiology - Primary mechanisms: Oncogenic EWSR1::FLI1 fusion establishes aberrant transcriptional networks by binding ETS motifs and GGAA microsatellites, remodeling chromatin into de novo super-enhancers and amplifying target gene expression; this produces lineage-inappropriate programs and replication/transcription stress (petrescu2024preclinicalmodelsfor pages 3-5). The limited co-mutation landscape underscores the centrality of the fusion (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). - Dysregulated pathways: EWSR1::FLI1-driven enhancer programs converge on growth and survival signaling; clinically and translationally, the IGF1R/PI3K–AKT–mTOR axis has been repeatedly implicated and targeted (jimenez2024anepigeneticapproach pages 21-24). EWSR1::FLI1 and menin activate ATF4 and the serine biosynthesis pathway, linking oncogenic transcription to metabolic support (jimenez2021ewsfli1andmenin pages 1-3). - Affected processes: Transcriptional regulation, enhancer biogenesis, RNA processing/replication coupling (R-loops), metabolic reprogramming (serine biosynthesis), and DDR pathway engagement (petrescu2024preclinicalmodelsfor pages 3-5, jimenez2021ewsfli1andmenin pages 1-3).

2) Key Molecular Players - Genes/proteins: EWSR1::FLI1 fusion (defining driver); TP53, STAG2, CDKN2A as recurrent alterations (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). ATF4 and PHGDH are upregulated downstream of fusion/menin (jimenez2021ewsfli1andmenin pages 1-3). - Chemical entities/drugs: Historical and ongoing targeting of IGF1R and mTOR in the clinic (jimenez2024anepigeneticapproach pages 21-24). - Cell types: Undifferentiated small round tumor cells; proposed permissive progenitors include mesenchymal and neural crest–related stem/progenitor states (petrescu2024preclinicalmodelsfor pages 3-5, jimenez2021ewsfli1andmenin pages 1-3). - Anatomical locations: Bone and soft tissues; commonly long bones and pelvis (review scope) (petrescu2024preclinicalmodelsfor pages 3-5).

3) Biological Processes (for GO annotation) - Positive regulation of transcription by RNA polymerase II and enhancer assembly at GGAA microsatellites (petrescu2024preclinicalmodelsfor pages 3-5). - Cellular response to stress and amino acid biosynthetic process (serine biosynthesis) via ATF4 (jimenez2021ewsfli1andmenin pages 1-3). - DNA damage response to replication stress/R-loop accumulation (petrescu2024preclinicalmodelsfor pages 3-5).

4) Cellular Components - Chromatin (enhancers/super-enhancers), nucleoplasm; plasma membrane marker CD99 (diagnostic) (petrescu2024preclinicalmodelsfor pages 3-5).

5) Disease Progression - Sequence: Initiation by EWSR1::FLI1 fusion in a developmentally defined, permissive progenitor; establishment of enhancer-driven transcriptional programs; induction of replication/transcription stress and DDR engagement; acquisition of cooperating CNAs or secondary hits (e.g., STAG2, TP53) that may influence progression and therapy response; clinical presentation with rapidly growing bone/soft tissue masses; therapeutic response with high cure rates in localized disease but frequent resistance and relapse in metastatic/recurrent settings (jimenez2024anepigeneticapproacha pages 21-24, petrescu2024preclinicalmodelsfor pages 3-5, jimenez2024anepigeneticapproach pages 21-24).

6) Phenotypic Manifestations - Clinical: Painful bone/soft tissue mass; histology of undifferentiated small round blue cells with strong CD99; aggressive course when metastatic (petrescu2024preclinicalmodelsfor pages 3-5, jimenez2024anepigeneticapproach pages 21-24). - Mechanistic links: Fusion-driven enhanceropathy underlies proliferation/immaturity; DDR stress explains sensitivity to DNA-damaging regimens and rationale for PARP targeting; ATF4/serine pathway supports biosynthetic needs of rapidly proliferating cells (petrescu2024preclinicalmodelsfor pages 3-5, jimenez2021ewsfli1andmenin pages 1-3).

Evidence items with PMIDs/DOIs/URLs and dates - Jiménez MS. An epigenetic approach for Ewing sarcoma patients. 2024. Details: fusion types (type I/II), low mutation burden, recurrent CNAs, STAG2/TP53, clinical outcomes, IGF1R/mTOR targeting (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). Publication year 2024. - Petrescu DI et al. Preclinical models for bone sarcomas. Front Oncol. Jul 2024; emphasizes EWSR1::FLI1 enhancer rewiring at GGAA microsatellites, R-loop/DDR vulnerabilities, CD99 phenotype. DOI: 10.3389/fonc.2024.1388484; URL: https://doi.org/10.3389/fonc.2024.1388484 (petrescu2024preclinicalmodelsfor pages 3-5). - Jiménez JA et al. EWS-FLI1 and menin converge to regulate ATF4 activity. Mol Cancer Res. Mar 2021; shows EWSR1::FLI1 binding at ATF4 promoter, menin dependence, serine biosynthesis upregulation. DOI: 10.1158/1541-7786.mcr-20-0679; URL: https://doi.org/10.1158/1541-7786.mcr-20-0679 (jimenez2021ewsfli1andmenin pages 1-3).

Direct quotes supporting key statements - “binds tandem GGAA microsatellite repeats” (on EWSR1::FLI1 enhancer binding) (petrescu2024preclinicalmodelsfor pages 3-5). - “ectopic expression alone often fails to recapitulate transformation,” emphasizing context dependency (jimenez2024anepigeneticapproacha pages 21-24).

Notes and limitations - Additional emerging mechanisms (e.g., detailed roles of Polycomb/LSD1, ferroptosis control, immune axes such as MIF–CD74, CD99 immunobiology, and liquid biopsy ctDNA measures) are active research areas but were not captured in the extracted evidence set used here; they should be integrated when primary 2023–2024 sources are available for citation.

Gene/protein annotations with ontology terms (examples; evidence-linked) - EWSR1 (HGNC:3508) and FLI1 (HGNC:3749): fusion oncoprotein EWSR1::FLI1; function: transcription factor activity; process: positive regulation of transcription, enhancer activation at GGAA microsatellites (petrescu2024preclinicalmodelsfor pages 3-5, jimenez2024anepigeneticapproacha pages 21-24). - ATF4 (HGNC:792): transcription factor; processes: cellular response to stress; regulation of serine biosynthetic process (jimenez2021ewsfli1andmenin pages 1-3). - PHGDH (HGNC:8922): serine biosynthesis enzyme; process: L-serine biosynthetic process (downstream of ATF4 in EwS) (jimenez2021ewsfli1andmenin pages 1-3). - TP53 (HGNC:11998), STAG2 (HGNC:11354), CDKN2A (HGNC:1787): tumor suppressors/cohesin; processes: DNA damage response, cell cycle regulation; alterations recurrent in EwS (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24).

Phenotype associations (HP terms; evidence-linked narrative) - HP:0009732 (Bone pain) and HP:0100753 (Bone neoplasm) consistent with EwS presentation; undifferentiated small round cell histology and strong CD99 immunostaining (petrescu2024preclinicalmodelsfor pages 3-5). (Note: phenotype terms aligned by clinical convention; narrative support from cited reviews.)

Cell type involvement (CL terms) - CL:0000134 (mesenchymal stem cell) and neural crest–related progenitors as permissive/transformed lineages; tumor cells are undifferentiated small round cells (petrescu2024preclinicalmodelsfor pages 3-5, jimenez2021ewsfli1andmenin pages 1-3).

Anatomical locations (UBERON terms) - UBERON:0001474 (long bone), UBERON:0002348 (pelvis) as common sites for primary EwS (review context) (petrescu2024preclinicalmodelsfor pages 3-5).

Chemical entities (CHEBI) - Agents targeting IGF1R/mTOR pathways have been trialed clinically in EwS; specific compounds not detailed in extracted text (jimenez2024anepigeneticapproach pages 21-24).

Citations - Jiménez MS. An epigenetic approach for Ewing sarcoma patients. 2024 (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24). - Petrescu DI et al. Preclinical models for the study of pediatric solid tumors: focus on bone sarcomas. Front Oncol. Jul 2024. DOI: 10.3389/fonc.2024.1388484. URL: https://doi.org/10.3389/fonc.2024.1388484 (petrescu2024preclinicalmodelsfor pages 3-5). - Jiménez JA et al. EWS-FLI1 and Menin Converge to Regulate ATF4 Activity in Ewing Sarcoma. Mol Cancer Res. Mar 2021. DOI: 10.1158/1541-7786.mcr-20-0679. URL: https://doi.org/10.1158/1541-7786.mcr-20-0679 (jimenez2021ewsfli1andmenin pages 1-3). - Additional overview excerpts on fusion structure/genomic landscape/outcomes from 2024 thesis (jimenez2024anepigeneticapproachb pages 21-24, jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24).

References (context IDs) (jimenez2024anepigeneticapproacha pages 21-24, jimenez2024anepigeneticapproach pages 21-24, petrescu2024preclinicalmodelsfor pages 3-5, jimenez2021ewsfli1andmenin pages 1-3, jimenez2024anepigeneticapproachb pages 21-24)

References

  1. (jimenez2024anepigeneticapproacha pages 21-24): M Sánchez Jiménez. An epigenetic approach for ewing sarcoma patients. Unknown journal, 2024.

  2. (jimenez2024anepigeneticapproach pages 21-24): M Sánchez Jiménez. An epigenetic approach for ewing sarcoma patients. Unknown journal, 2024.

  3. (jimenez2024anepigeneticapproachb pages 21-24): M Sánchez Jiménez. An epigenetic approach for ewing sarcoma patients. Unknown journal, 2024.

  4. (petrescu2024preclinicalmodelsfor pages 3-5): D. I. Petrescu, J. Yustein, Atreyi Dasgupta, Joanna Kitlinska, and Massimo Broggini. Preclinical models for the study of pediatric solid tumors: focus on bone sarcomas. Frontiers in Oncology, Jul 2024. URL: https://doi.org/10.3389/fonc.2024.1388484, doi:10.3389/fonc.2024.1388484. This article has 7 citations and is from a poor quality or predatory journal.

  5. (jimenez2021ewsfli1andmenin pages 1-3): Jennifer A. Jiménez, April A. Apfelbaum, Allegra G. Hawkins, Laurie K. Svoboda, Abhijay Kumar, Ramon Ocadiz Ruiz, Alessandra X. Garcia, Elena Haarer, Zeribe C. Nwosu, Joshua Bradin, Trupta Purohit, Dong Chen, Tomasz Cierpicki, Jolanta Grembecka, Costas A. Lyssiotis, and Elizabeth R. Lawlor. Ews-fli1 and menin converge to regulate atf4 activity in ewing sarcoma. Molecular Cancer Research, 19:1182-1195, Mar 2021. URL: https://doi.org/10.1158/1541-7786.mcr-20-0679, doi:10.1158/1541-7786.mcr-20-0679. This article has 13 citations and is from a peer-reviewed journal.