Ewing sarcoma is an aggressive pediatric bone and soft tissue malignancy characterized by the pathognomonic EWS-FLI1 fusion gene, present in approximately 85% of cases. This translocation t(11;22)(q24;q12) creates a chimeric transcription factor that aberrantly activates genes driving proliferation and blocks differentiation. The EWS-FLI1 fusion is both diagnostic and represents a compelling but challenging therapeutic target. Ewing sarcoma exemplifies the concept of fusion oncogene-driven cancer with a single genetic driver.
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name: Ewing Sarcoma
creation_date: '2026-01-26T02:55:13Z'
updated_date: '2026-05-03T05:12:56Z'
description: >-
Ewing sarcoma is an aggressive pediatric bone and soft tissue malignancy
characterized by the pathognomonic EWS-FLI1 fusion gene, present in approximately
85% of cases. This translocation t(11;22)(q24;q12) creates a chimeric transcription
factor that aberrantly activates genes driving proliferation and blocks
differentiation. The EWS-FLI1 fusion is both diagnostic and represents a compelling
but challenging therapeutic target. Ewing sarcoma exemplifies the concept of
fusion oncogene-driven cancer with a single genetic driver.
categories:
- Pediatric Cancer
- Bone Cancer
- Sarcoma
parents:
- bone sarcoma
has_subtypes:
- name: Osseous Ewing Sarcoma
description: >-
Primary tumors arising in bone, most commonly the pelvis, femur, and other
long bones. Accounts for approximately 80% of Ewing sarcoma cases. Typically
presents with localized pain and swelling.
- name: Extraosseous Ewing Sarcoma
description: >-
Primary tumors arising in soft tissues outside of bone. Can occur in chest
wall, paravertebral region, or extremities. Shares the same EWS-FLI1 fusion
and treated similarly to osseous disease.
pathophysiology:
- name: EWS-FLI1 Fusion Oncogene
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 transcription factor that activates proliferative genes and
represses differentiation programs. This single genetic event is the primary
driver of Ewing sarcoma.
cell_types:
- preferred_term: mesenchymal stem cell
term:
id: CL:0000134
label: mesenchymal stem cell
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
locations:
- preferred_term: bone tissue
term:
id: UBERON:0002481
label: bone tissue
downstream:
- target: Aberrant Transcriptional Regulation
description: EWS-FLI1 binds GGAA microsatellites to create de novo enhancers
- target: Blocked Differentiation
description: EWS-FLI1 represses mesenchymal differentiation programs
evidence:
- reference: PMID:33741715
reference_title: "EWS-FLI1 and Menin Converge to Regulate ATF4 Activity in Ewing Sarcoma."
supports: PARTIAL
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"
explanation: Directly supports the 85% frequency of EWS-FLI1 translocation and its structural details.
- reference: PMID:17250957
reference_title: "The Biology of Ewing sarcoma."
supports: SUPPORT
snippet: "resulting EWS-FLI-1 fusion protein is believed to behave as an aberrant"
explanation: Supports the role of EWS-FLI1 as an aberrant transcription factor driving tumor development.
- name: Aberrant Transcriptional Regulation
description: >-
EWS-FLI1 binds to GGAA microsatellite repeats throughout the genome, creating
de novo enhancers that activate oncogenic target genes including NKX2-2, NR0B1,
and IGF1. This abnormal enhancer activity reprograms cell identity and drives
the Ewing sarcoma phenotype.
biological_processes:
- preferred_term: regulation of gene expression
modifier: ABNORMAL
term:
id: GO:0010468
label: regulation of gene expression
downstream:
- target: Blocked Differentiation
description: Aberrant enhancer activity maintains undifferentiated state
evidence:
- reference: PMID:33741715
reference_title: "EWS-FLI1 and Menin Converge to Regulate ATF4 Activity in Ewing Sarcoma."
supports: PARTIAL
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 transcriptional activation by EWS-FLI1, but not all specific enhancer-mechanism details in the descriptor.
- name: Blocked Differentiation
description: >-
EWS-FLI1 represses genes required for mesenchymal differentiation, maintaining
cells in a proliferative, undifferentiated state. The cell of origin remains
debated but may be a neural crest-derived mesenchymal progenitor.
biological_processes:
- preferred_term: cell differentiation
modifier: DECREASED
term:
id: GO:0030154
label: 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: "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.
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.
evidence:
- reference: PMID:35117540
reference_title: "Effects of different treatments and other factors on the prognosis of patients with ewing sarcoma."
supports: SUPPORT
snippet: "Ewing sarcoma is a small round cell tumor of bone or soft tissue"
explanation: Abstract defines Ewing sarcoma as a small round cell tumor of bone or soft tissue.
phenotypes:
- category: Musculoskeletal
name: Bone Pain
diagnostic: true
description: >-
Localized bone pain is a common presenting symptom and may be present for
weeks to months before diagnosis. Pain may be intermittent initially and
worsen progressively.
phenotype_term:
preferred_term: Bone pain
term:
id: HP:0002653
label: Bone pain
evidence:
- reference: PMID:30215968
reference_title: "Bone Cancer: Diagnosis and Treatment Principles."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: "Timely diagnosis is challenging"
explanation: Supports nonspecific musculoskeletal presentation of primary bone cancers, but does not directly quantify bone pain in Ewing sarcoma.
- category: Musculoskeletal
name: Soft Tissue Mass / Localized Swelling
frequency: VERY_FREQUENT
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
- category: Constitutional
name: Fever
frequency: OCCASIONAL
description: >-
Systemic symptoms including fever may occur, sometimes leading to initial
misdiagnosis as osteomyelitis.
phenotype_term:
preferred_term: Fever
term:
id: HP:0001945
label: Fever
- category: Constitutional
name: Weight Loss
frequency: OCCASIONAL
description: >-
Unintentional weight loss may occur with advanced or metastatic disease.
phenotype_term:
preferred_term: Weight loss
term:
id: HP:0001824
label: Weight loss
- category: Systemic
name: Metastatic Disease
frequency: FREQUENT
description: >-
Approximately 25% of patients have metastases at diagnosis, most commonly
to lungs, bone, and bone marrow. Metastatic disease significantly worsens
prognosis with five-year survival dropping to 20-30%.
phenotype_term:
preferred_term: Neoplasm
term:
id: HP:0002664
label: Neoplasm
evidence:
- reference: PMID:30215968
reference_title: "Bone Cancer: Diagnosis and Treatment Principles."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "lowers the five-year survival rate to 20% to 30%."
explanation: Confirms that metastatic disease lowers five-year survival to 20-30%.
- reference: PMID:17301523
reference_title: "[Ewing sarcoma]."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "an approximately 10-30% 5-year event-free survival rate."
explanation: Confirms the poor prognosis for metastatic Ewing sarcoma with quantitative survival data.
- reference: PMID:36669140
reference_title: "Randomized Phase III Trial of Ganitumab With Interval-Compressed Chemotherapy for Patients With Newly Diagnosed Metastatic Ewing Sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The 3-year EFS estimates were 37.4%"
explanation: Provides precise 3-year EFS data from the COG AEWS1221 phase III trial for metastatic Ewing sarcoma.
- category: Musculoskeletal
name: Pathologic Fracture
frequency: OCCASIONAL
description: >-
Pathologic fracture through weakened bone may be the presenting event in
some patients. Bone destruction by tumor reduces structural integrity.
phenotype_term:
preferred_term: Pathologic fracture
term:
id: HP:0002756
label: Pathologic fracture
- category: Hematologic
name: Anemia
frequency: OCCASIONAL
description: >-
Anemia may be present, particularly in patients with advanced or metastatic
disease. It can result from bone marrow involvement or chronic disease.
phenotype_term:
preferred_term: Anemia
term:
id: HP:0001903
label: Anemia
biochemical:
- name: EWS-FLI1 Fusion Detection
notes: >-
RT-PCR or FISH detection of EWS-FLI1 fusion (or variant EWS-ERG, EWS-ETV1)
is diagnostic. Approximately 85% have EWS-FLI1, and most others have
alternative ETS family fusions.
evidence:
- reference: PMID:17301523
reference_title: "[Ewing sarcoma]."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "EWS-FLI 1 among Ewing sarcoma"
explanation: Supports molecular detection of EWS-FLI1 fusion as a defining diagnostic feature.
genetic:
- name: EWS-FLI1 Fusion
association: Somatic Fusion Oncogene
notes: >-
The t(11;22)(q24;q12) translocation creates the EWS-FLI1 fusion in 85%
of cases. EWS-ERG t(21;22) accounts for most remaining cases. All Ewing
sarcomas harbor EWS-ETS family fusions, which are both diagnostic and
represent the primary oncogenic driver.
evidence:
- reference: PMID:17250957
reference_title: "The Biology of Ewing sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "It is associated in 85% of cases with the"
explanation: Directly confirms the 85% frequency of the t(11;22) translocation creating EWS-FLI1.
treatments:
- name: Neoadjuvant Chemotherapy
description: >-
Intensive multi-agent chemotherapy (vincristine, doxorubicin, cyclophosphamide
alternating with ifosfamide/etoposide - VDC/IE) is standard. Neoadjuvant
chemotherapy shrinks tumors before local control.
treatment_term:
preferred_term: chemotherapy
term:
id: MAXO:0000647
label: 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:4026
label: cyclophosphamide hydrate
- preferred_term: ifosfamide
term:
id: CHEBI:5864
label: ifosfamide
- preferred_term: etoposide
term:
id: CHEBI:4911
label: etoposide
evidence:
- reference: PMID:20152770
reference_title: "Ewing's sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Cooperative group studies have led to chemotherapy regimens"
explanation: Confirms the five-drug chemotherapy backbone used in Ewing sarcoma treatment.
- reference: PMID:17301523
reference_title: "[Ewing sarcoma]."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "standard chemotherapy for localized ESFT"
explanation: Confirms VDC/IE as the standard North American chemotherapy regimen for Ewing sarcoma.
- reference: PMID:36669140
reference_title: "Randomized Phase III Trial of Ganitumab With Interval-Compressed Chemotherapy for Patients With Newly Diagnosed Metastatic Ewing Sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "interval-compressed vincristine/doxorubicin/cyclophosphamide alternating once"
explanation: Confirms VDC/IE as standard chemotherapy backbone in the COG phase III trial for metastatic Ewing sarcoma.
- name: Surgical Resection
description: >-
Wide surgical resection with negative margins is preferred when feasible
without excessive morbidity. Reconstruction may be needed for limb salvage.
treatment_term:
preferred_term: surgical procedure
term:
id: MAXO:0000004
label: surgical procedure
evidence:
- reference: PMID:35117540
reference_title: "Effects of different treatments and other factors on the prognosis of patients with ewing sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "CT combined surgery achieved"
explanation: Supports that chemotherapy combined with surgery achieves the best survival outcomes.
- 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.
treatment_term:
preferred_term: radiation therapy
term:
id: MAXO:0000014
label: radiation therapy
evidence:
- reference: PMID:33818887
reference_title: "Ewing sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "surgery, definitive radiation, or a combination of surgery and radiation"
explanation: Confirms the role of definitive radiation as a local treatment option in Ewing sarcoma management.
- name: Adjuvant Chemotherapy
description: >-
Additional chemotherapy after local control to eliminate micrometastatic
disease. Total treatment duration is typically 9-12 months.
treatment_term:
preferred_term: chemotherapy
term:
id: MAXO:0000647
label: chemotherapy
disease_term:
preferred_term: Ewing sarcoma
term:
id: MONDO:0012817
label: Ewing sarcoma
classifications:
icdo_morphology:
classification_value: Sarcoma
harrisons_chapter:
- classification_value: cancer
- classification_value: solid tumor
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
(jimenez2024anepigeneticapproacha pages 21-24): M Sánchez Jiménez. An epigenetic approach for ewing sarcoma patients. Unknown journal, 2024.
(jimenez2024anepigeneticapproach pages 21-24): M Sánchez Jiménez. An epigenetic approach for ewing sarcoma patients. Unknown journal, 2024.
(jimenez2024anepigeneticapproachb pages 21-24): M Sánchez Jiménez. An epigenetic approach for ewing sarcoma patients. Unknown journal, 2024.
(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.
(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.