Synovial sarcoma is a translocation-driven soft tissue sarcoma characterized by the pathognomonic SS18-SSX fusion gene, present in virtually all cases. Despite its name, synovial sarcoma does not arise from synovial tissue and the cell of origin remains uncertain. It typically affects adolescents and young adults, with peak incidence in the third decade. Common sites include the extremities, particularly around large joints, but it can occur anywhere including head, neck, and trunk. The SS18-SSX fusion disrupts chromatin remodeling through interaction with the SWI/SNF complex, leading to epigenetic reprogramming that drives oncogenesis.
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name: Synovial Sarcoma
creation_date: '2026-01-26T02:55:13Z'
updated_date: '2026-05-02T00:00:00Z'
description: >-
Synovial sarcoma is a translocation-driven soft tissue sarcoma characterized
by the pathognomonic SS18-SSX fusion gene, present in virtually all cases.
Despite its name, synovial sarcoma does not arise from synovial tissue and
the cell of origin remains uncertain. It typically affects adolescents and
young adults, with peak incidence in the third decade. Common sites include
the extremities, particularly around large joints, but it can occur anywhere
including head, neck, and trunk. The SS18-SSX fusion disrupts chromatin
remodeling through interaction with the SWI/SNF complex, leading to epigenetic
reprogramming that drives oncogenesis.
categories:
- Soft Tissue Sarcoma
- Sarcoma
- Young Adult Cancer
parents:
- soft tissue sarcoma
has_subtypes:
- name: Biphasic Synovial Sarcoma
description: >-
Contains both epithelial and spindle cell components with distinct glandular
or epithelial differentiation. Accounts for approximately 20-30% of cases.
- name: Monophasic Synovial Sarcoma
description: >-
Composed predominantly of spindle cells without obvious epithelial component.
The most common subtype, accounting for 50-60% of cases. Can be more difficult
to diagnose histologically.
- name: Poorly Differentiated Synovial Sarcoma
description: >-
High-grade variant with round cell or epithelioid morphology. Associated
with more aggressive behavior and worse prognosis.
pathophysiology:
- name: SS18-SSX Fusion Oncogene
description: >-
The t(X;18)(p11;q11) translocation fuses the SS18 gene on chromosome 18 to
one of three SSX genes (SSX1, SSX2, or rarely SSX4) on the X chromosome.
The SS18-SSX fusion protein disrupts the BAF (SWI/SNF) chromatin remodeling
complex, leading to aberrant transcriptional regulation and epigenetic
reprogramming.
evidence:
- reference: PMID:32092619
reference_title: "An evidence-based guideline on the application of molecular testing in the diagnosis, prediction of prognosis, and selection of therapy in non-GIST soft tissue sarcomas."
supports: PARTIAL
snippet: "SS18 (SYT) break-apart by FISH or SS18-SSX (SYT-SSX) fusion by reverse transcription-polymerase chain reaction is recommended as a sensitive and specific test to differentiate patients with synovial sarcoma from other sarcomas."
explanation: "Supports the presence of SS18-SSX fusions as a defining feature of synovial sarcoma."
- reference: PMID:31681608
reference_title: "Epigenetic Targets in Synovial Sarcoma: A Mini-Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "It is characterized by the recurrent pathognomonic chromosomal translocation t(X;18)(p11.2;q11.2) that most frequently fuses SSX1 or SSX2 genes with SS18."
explanation: "Confirms the SS18-SSX fusion as the pathognomonic translocation defining synovial sarcoma."
biological_processes:
- preferred_term: chromatin remodeling
modifier: ABNORMAL
term:
id: GO:0006338
label: chromatin remodeling
downstream:
- target: BAF Complex Disruption
description: SS18-SSX integrates into BAF complex altering its function
- target: Epigenetic Reprogramming
description: Altered chromatin remodeling leads to aberrant gene expression
- name: BAF Complex Disruption
description: >-
The SS18-SSX fusion protein incorporates into the BAF chromatin remodeling
complex, displacing wild-type SS18. This alters BAF complex targeting and
function, particularly affecting polycomb-mediated gene repression. The
fusion protein causes eviction of BAF47 (SMARCB1) from the complex at certain
genomic loci.
evidence:
- reference: PMID:29861296
reference_title: "The SS18-SSX Fusion Oncoprotein Hijacks BAF Complex Targeting and Function to Drive Synovial Sarcoma."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "SS18-SSX globally hijacks BAF complexes on chromatin to activate an SS transcriptional signature that we define using primary tumors and cell lines."
explanation: "Demonstrates that SS18-SSX retargets BAF complexes genome-wide, hijacking their chromatin targeting."
- reference: PMID:29861296
reference_title: "The SS18-SSX Fusion Oncoprotein Hijacks BAF Complex Targeting and Function to Drive Synovial Sarcoma."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "SS18-SSX retargets BAF complexes from enhancers to broad polycomb domains to oppose PRC2-mediated repression and activate bivalent genes."
explanation: "Shows that the fusion protein redirects BAF complexes from enhancers to polycomb domains."
biological_processes:
- preferred_term: regulation of gene expression
modifier: ABNORMAL
term:
id: GO:0010468
label: regulation of gene expression
downstream:
- target: Epigenetic Reprogramming
description: BAF complex retargeting leads to aberrant polycomb domain activation
- name: Epigenetic Reprogramming
description: >-
SS18-SSX-containing BAF complexes fail to properly oppose polycomb repressive
complexes, leading to abnormal silencing of tumor suppressors and activation
of oncogenic programs. Key target genes include BCL2 (antiapoptotic) and
multiple receptor tyrosine kinases. The SS18-SSX fusion also activates
downstream effectors including YAP1/TAZ and beta-catenin transcriptional
programs.
evidence:
- reference: PMID:31681608
reference_title: "Epigenetic Targets in Synovial Sarcoma: A Mini-Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "This leads to the expression of the SS18-SSX fusion protein, which causes disturbances in several interacting multiprotein complexes such as the SWItch/Sucrose Non-Fermentable (SWI/SNF) complex, also known as the BAF complex and the Polycomb Repressive Complex 1 and 2 (PRC1 and PRC2)."
explanation: "Confirms that SS18-SSX disrupts both SWI/SNF and PRC1/2 complexes leading to epigenetic rewiring."
- reference: PMID:36920288
reference_title: "Interdependence of SS18-SSX-driven YAP1 and beta-Catenin Activation in Synovial Sarcoma."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "YAP1, TAZ, and β-catenin transcriptional activity is not only stimulated by the SS18-SSX fusion protein, but that they also mutually enhance each other's activation."
explanation: "Demonstrates that SS18-SSX activates YAP1/TAZ and beta-catenin as downstream effectors of its epigenetic reprogramming."
biological_processes:
- preferred_term: apoptotic process
modifier: DECREASED
term:
id: GO:0006915
label: apoptotic process
histopathology:
- name: Synovial Sarcoma
finding_term:
preferred_term: Synovial Sarcoma
term:
id: NCIT:C3400
label: Synovial Sarcoma
frequency: VERY_FREQUENT
description: Synovial sarcoma is a rare soft tissue tumor.
evidence:
- reference: PMID:9930576
reference_title: "Synovial sarcoma."
supports: SUPPORT
snippet: "Synovial sarcoma is a rare soft tissue tumor of children and adults that is"
explanation: Abstract describes synovial sarcoma as a rare soft tissue tumor.
phenotypes:
- category: Musculoskeletal
name: Soft Tissue Mass
frequency: VERY_FREQUENT
diagnostic: true
description: >-
A slowly growing soft tissue mass, often present for months to years before
diagnosis. Most commonly located in the lower extremities near joints but
not within the joint itself. The mass is typically deep-seated and firm.
phenotype_term:
preferred_term: Soft tissue neoplasm
term:
id: HP:0031459
label: Soft tissue neoplasm
evidence:
- reference: PMID:31681608
reference_title: "Epigenetic Targets in Synovial Sarcoma: A Mini-Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "SS occurs primarily in the limbs, often near joints, but can present anywhere."
explanation: "Confirms the typical presentation of synovial sarcoma as a mass in the limbs near joints."
- category: Musculoskeletal
name: Localized Pain
frequency: FREQUENT
description: >-
Pain and tenderness at the tumor site, which may be attributed to other
causes given the young patient age. Pain may worsen with tumor growth.
phenotype_term:
preferred_term: Pain
term:
id: HP:0012531
label: Pain
- category: Constitutional
name: Weight Loss
frequency: OCCASIONAL
description: >-
Weight loss is uncommon at presentation but 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: OCCASIONAL
description: >-
Lung metastases occur in approximately 50% of patients over the disease
course. Metastatic disease at presentation is relatively uncommon.
phenotype_term:
preferred_term: Neoplasm
term:
id: HP:0002664
label: Neoplasm
- category: Musculoskeletal
name: Tumor Calcification/Ossification
description: >-
Calcification or ossification within the soft tissue tumor mass is seen in
a subset of synovial sarcomas. Calcifying and ossifying synovial sarcoma
subtypes are recognized as behaviorally distinct.
phenotype_term:
preferred_term: Tumor calcification/ossification
evidence:
- reference: PMID:9930576
reference_title: "Synovial sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "behaviorally distinct calcifying, ossifying, and poorly differentiated subtypes can be recognized"
explanation: "Confirms calcification as a recognized feature of synovial sarcoma subtypes."
- category: Respiratory
name: Pulmonary Metastases
description: >-
Lung metastases are the most common site of distant spread and develop
in approximately 50% of patients during the disease course. Adult patients
have a higher rate of metastatic disease at diagnosis compared to pediatric
patients.
phenotype_term:
preferred_term: Neoplasm of the lung
term:
id: HP:0100526
label: Neoplasm of the lung
evidence:
- reference: PMID:31681608
reference_title: "Epigenetic Targets in Synovial Sarcoma: A Mini-Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "the 50% observed in newly diagnosed adult patients"
explanation: "Confirms the high rate of metastatic disease in adult synovial sarcoma patients."
biochemical:
- name: SS18-SSX Fusion Detection
notes: >-
RT-PCR, FISH, or next-generation sequencing detection of the SS18-SSX fusion
is diagnostic. The fusion type (SSX1 vs SSX2) may have prognostic significance,
with SS18-SSX1 historically associated with worse outcomes.
evidence:
- reference: PMID:15208645
reference_title: "A novel FISH assay for SS18-SSX fusion type in synovial sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "it has been shown that in synovial sarcoma a clear correlation exists between the type of fusion gene and histologic subtype and, more importantly, clinical outcome"
explanation: "Confirms that fusion type correlates with histologic subtype and clinical outcome."
- name: TLE1 Immunohistochemistry
notes: >-
TLE1 is a highly sensitive marker for synovial sarcoma, positive in >95%
of cases. Combined with morphology and SS18-SSX fusion status, it aids
diagnosis.
evidence:
- reference: PMID:19809272
reference_title: "Prospective evaluation of TLE1 as a diagnostic immunohistochemical marker in synovial sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "TLE1 encodes a transcriptional corepressor that is overexpressed in synovial sarcomas."
explanation: "Confirms TLE1 overexpression in synovial sarcomas."
- name: Cytokeratin and EMA Expression
notes: >-
Most synovial sarcomas are immunoreactive for cytokeratin and epithelial
membrane antigen (EMA), reflecting the epithelial differentiation capacity
of the tumor. BCL2 positivity is also characteristic.
evidence:
- reference: PMID:9930576
reference_title: "Synovial sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Most synovial sarcomas are immunoreactive for cytokeratin, epithelial membrane antigen, and bc12 protein"
explanation: "Confirms characteristic immunohistochemical profile of synovial sarcoma."
- name: Cancer-Testis Antigen Expression
notes: >-
Synovial sarcomas frequently express cancer-testis antigens including
NY-ESO-1, PRAME, and MAGEA4, providing a biologic rationale for
antigen-directed cellular immunotherapy.
evidence:
- reference: PMID:27993576
reference_title: "Cancer-testis antigen expression in synovial sarcoma: NY-ESO-1, PRAME, MAGEA4, and MAGEA1."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "NY-ESO-1, PRAME, MAGEA4, and MAGEA1 were positive in 66 (61%), 93 (86%), 89 (82%), and 16 (15%) of 108 SSs, respectively"
explanation: "Documents frequent NY-ESO-1, PRAME, and MAGEA4 expression in synovial sarcoma specimens."
- reference: PMID:27993576
reference_title: "Cancer-testis antigen expression in synovial sarcoma: NY-ESO-1, PRAME, MAGEA4, and MAGEA1."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "These data support the potential utility of NY-ESO-1, PRAME, and MAGEA4 as immunotherapy targets and ancillary prognostic parameters"
explanation: "Supports interpreting these cancer-testis antigens as targetable synovial sarcoma biomarkers."
genetic:
- name: SS18-SSX Fusion
association: Somatic Fusion Oncogene
notes: >-
The t(X;18)(p11;q11) translocation is present in virtually all synovial
sarcomas. SS18-SSX1 fusion occurs in approximately 65% and SS18-SSX2 in
35% of cases. This fusion is both diagnostic and represents the primary
oncogenic driver.
evidence:
- reference: PMID:15208645
reference_title: "A novel FISH assay for SS18-SSX fusion type in synovial sarcoma."
supports: PARTIAL
snippet: "The t(X;18)(p11.2;q11.2) is the cytogenetic hallmark of synovial sarcoma and is present in more than 90% of the cases."
explanation: "Abstract notes t(X;18) as the cytogenetic hallmark of synovial sarcoma."
- reference: PMID:15208645
reference_title: "A novel FISH assay for SS18-SSX fusion type in synovial sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "It produces three types of fusion gene formed in part by SS18 from chromosome 18 and by SSX1, SSX2 or, rarely, SSX4 from the X chromosome."
explanation: "Confirms the three types of SS18-SSX fusion genes."
- name: Low Mutational Burden
association: Genomic Characteristic
notes: >-
Synovial sarcoma tumors are mutationally quiet, with few additional genomic
alterations beyond the defining translocation. Increased genomic complexity
is associated with poor prognosis and metastatic disease.
evidence:
- reference: PMID:31681608
reference_title: "Epigenetic Targets in Synovial Sarcoma: A Mini-Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Other than the translocation, SS tumors are mutationally quiet."
explanation: "Confirms the low mutational burden of synovial sarcoma beyond the defining translocation."
treatments:
- name: Surgical Resection
description: >-
Wide surgical resection with negative margins is the primary treatment
for localized disease. Limb-sparing surgery is preferred when oncologically
feasible.
treatment_term:
preferred_term: surgical procedure
term:
id: MAXO:0000004
label: surgical procedure
evidence:
- reference: PMID:31681608
reference_title: "Epigenetic Targets in Synovial Sarcoma: A Mini-Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "surgical resection remains the only long-term curative technique"
explanation: "Confirms that surgical resection is the primary curative treatment for synovial sarcoma."
- name: Radiation Therapy
description: >-
Adjuvant radiation improves local control, particularly for tumors larger
than 5 cm, high grade, or with close/positive margins. May be given
preoperatively or postoperatively.
treatment_term:
preferred_term: radiation therapy
term:
id: MAXO:0000014
label: radiation therapy
evidence:
- reference: PMID:31681608
reference_title: "Epigenetic Targets in Synovial Sarcoma: A Mini-Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "systemic therapy for pediatric SS relies on heavy use of doxorubicin and ifosfamide associated with radiotherapy for local control"
explanation: "Confirms the role of radiotherapy in local control of synovial sarcoma."
- name: Chemotherapy
description: >-
Doxorubicin with or without ifosfamide is the standard first-line systemic
therapy for unresectable or metastatic disease. Second-line options have
limited efficacy with response rates around 9%.
treatment_term:
preferred_term: chemotherapy
term:
id: MAXO:0000647
label: chemotherapy
therapeutic_agent:
- preferred_term: ifosfamide
term:
id: CHEBI:5864
label: ifosfamide
- preferred_term: doxorubicin
term:
id: CHEBI:28748
label: doxorubicin
evidence:
- reference: PMID:35405680
reference_title: "Poor Treatment Outcomes with Second-Line Chemotherapy in Advanced Synovial Sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Doxorubicin with or without ifosfamide therapy is the standard first-line treatment for unresectable or metastatic SS."
explanation: "Confirms doxorubicin +/- ifosfamide as the standard first-line chemotherapy."
- reference: PMID:35405680
reference_title: "Poor Treatment Outcomes with Second-Line Chemotherapy in Advanced Synovial Sarcoma."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "the response rate of second-line chemotherapy regimens for patients with SS was 9.4%"
explanation: "Demonstrates the poor efficacy of second-line chemotherapy in synovial sarcoma."
- name: Afamitresgene Autoleucel TCR-T Therapy
description: >-
Afamitresgene autoleucel is an engineered T-cell receptor therapy for
selected HLA-A*02-positive, MAGE-A4-expressing advanced synovial sarcoma
after prior anthracycline- or ifosfamide-containing chemotherapy.
treatment_term:
preferred_term: immunotherapy procedure
term:
id: MAXO:0001002
label: immunotherapy procedure
evidence:
- reference: PMID:38554725
reference_title: "Afamitresgene autoleucel for advanced synovial sarcoma and myxoid round cell liposarcoma (SPEARHEAD-1): an international, open-label, phase 2 trial."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Cohort 1 included patients with HLA-A*02, aged 16-75 years, with metastatic or unresectable synovial sarcoma or myxoid round cell liposarcoma (confirmed by cytogenetics) expressing MAGE-A4"
explanation: "Defines the synovial sarcoma population treated with afamitresgene autoleucel in SPEARHEAD-1."
- reference: PMID:38554725
reference_title: "Afamitresgene autoleucel for advanced synovial sarcoma and myxoid round cell liposarcoma (SPEARHEAD-1): an international, open-label, phase 2 trial."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Overall response rate was 37% (19 of 52; 95% CI 24-51) overall, 39% (17 of 44; 24-55) for patients with synovial sarcoma"
explanation: "Reports clinically meaningful responses in the synovial sarcoma subgroup treated with afamitresgene autoleucel."
disease_term:
preferred_term: synovial sarcoma
term:
id: MONDO:0010434
label: synovial sarcoma
classifications:
icdo_morphology:
classification_value: Sarcoma
harrisons_chapter:
- classification_value: cancer
- classification_value: solid tumor
references:
- reference: DOI:10.1038/s41388-025-03547-1
title: 'Molecular and epigenetic oncogenesis in synovial sarcoma: implications for cancer biology, diagnosis and treatment'
found_in:
- Synovial_Sarcoma-deep-research-falcon.md
findings:
- statement: The SS18::SSX oncogene is the driver of synovial sarcoma, an aggressive cancer presenting in young adults that has poor long-term outcomes.
supporting_text: The SS18::SSX oncogene is the driver of synovial sarcoma, an aggressive cancer presenting in young adults that has poor long-term outcomes.
evidence:
- reference: DOI:10.1038/s41388-025-03547-1
reference_title: 'Molecular and epigenetic oncogenesis in synovial sarcoma: implications for cancer biology, diagnosis and treatment'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: The SS18::SSX oncogene is the driver of synovial sarcoma, an aggressive cancer presenting in young adults that has poor long-term outcomes.
explanation: Deep research cited this publication as relevant literature for Synovial Sarcoma.
- reference: DOI:10.1038/s41594-023-01096-3
title: Aberrant gene activation in synovial sarcoma relies on SSX specificity and increased PRC1.1 stability
found_in:
- Synovial_Sarcoma-deep-research-falcon.md
findings:
- statement: The SS18-SSX fusion drives oncogenic transformation in synovial sarcoma by bridging SS18, a member of the mSWI/SNF (BAF) complex, to Polycomb repressive complex 1 (PRC1) target genes.
supporting_text: The SS18-SSX fusion drives oncogenic transformation in synovial sarcoma by bridging SS18, a member of the mSWI/SNF (BAF) complex, to Polycomb repressive complex 1 (PRC1) target genes.
evidence:
- reference: DOI:10.1038/s41594-023-01096-3
reference_title: Aberrant gene activation in synovial sarcoma relies on SSX specificity and increased PRC1.1 stability
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: The SS18-SSX fusion drives oncogenic transformation in synovial sarcoma by bridging SS18, a member of the mSWI/SNF (BAF) complex, to Polycomb repressive complex 1 (PRC1) target genes.
explanation: Deep research cited this publication as relevant literature for Synovial Sarcoma.
- reference: DOI:10.1097/pas.0000000000001447
title: A Novel SS18-SSX Fusion-specific Antibody for the Diagnosis of Synovial Sarcoma
found_in:
- Synovial_Sarcoma-deep-research-falcon.md
findings:
- statement: Synovial sarcoma (SS), an aggressive soft tissue sarcoma with a predilection for the extremities of young adults, harbors the pathognomonic t(X;18)(p11;q11) translocation, resulting in SS18-SSX rearrangements.
supporting_text: Synovial sarcoma (SS), an aggressive soft tissue sarcoma with a predilection for the extremities of young adults, harbors the pathognomonic t(X;18)(p11;q11) translocation, resulting in SS18-SSX rearrangements.
evidence:
- reference: DOI:10.1097/pas.0000000000001447
reference_title: A Novel SS18-SSX Fusion-specific Antibody for the Diagnosis of Synovial Sarcoma
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Synovial sarcoma (SS), an aggressive soft tissue sarcoma with a predilection for the extremities of young adults, harbors the pathognomonic t(X;18)(p11;q11) translocation, resulting in SS18-SSX rearrangements.
explanation: Deep research cited this publication as relevant literature for Synovial Sarcoma.
- reference: DOI:10.1515/oncologie-2024-0101
title: 'Primary renal synovial sarcomas diagnosed by a novel fusion gene with the fusion site involving exons of SS18 and SSX2: a case report'
found_in:
- Synovial_Sarcoma-deep-research-falcon.md
findings:
- statement: Primary renal synovial sarcoma (PRSS) is an uncommon malignancy with diagnostic challenges and poor prognosis.
supporting_text: Primary renal synovial sarcoma (PRSS) is an uncommon malignancy with diagnostic challenges and poor prognosis.
evidence:
- reference: DOI:10.1515/oncologie-2024-0101
reference_title: 'Primary renal synovial sarcomas diagnosed by a novel fusion gene with the fusion site involving exons of SS18 and SSX2: a case report'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Primary renal synovial sarcoma (PRSS) is an uncommon malignancy with diagnostic challenges and poor prognosis.
explanation: Deep research cited this publication as relevant literature for Synovial Sarcoma.
- reference: DOI:10.2147/cmar.s404371
title: 'Treatment at Relapse for Synovial Sarcoma of Children, Adolescents and Young Adults: From the State of Art to Future Clinical Perspectives'
found_in:
- Synovial_Sarcoma-deep-research-falcon.md
findings:
- statement: 'Treatment at Relapse for Synovial Sarcoma of Children, Adolescents and Young Adults: From the State of Art to Future Clinical Perspectives'
supporting_text: 'Treatment at Relapse for Synovial Sarcoma of Children, Adolescents and Young Adults: From the State of Art to Future Clinical Perspectives'
- reference: DOI:10.3389/fonc.2023.1123464
title: Emerging targeted and cellular therapies in the treatment of advanced and metastatic synovial sarcoma
found_in:
- Synovial_Sarcoma-deep-research-falcon.md
findings:
- statement: Synovial sarcoma is a soft tissue sarcoma accounting for approximately 1,000 cases per year in the United States.
supporting_text: Synovial sarcoma is a soft tissue sarcoma accounting for approximately 1,000 cases per year in the United States.
evidence:
- reference: DOI:10.3389/fonc.2023.1123464
reference_title: Emerging targeted and cellular therapies in the treatment of advanced and metastatic synovial sarcoma
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Synovial sarcoma is a soft tissue sarcoma accounting for approximately 1,000 cases per year in the United States.
explanation: Deep research cited this publication as relevant literature for Synovial Sarcoma.
- reference: DOI:10.3390/cancers15153887
title: Innovative Breakthroughs for the Treatment of Advanced and Metastatic Synovial Sarcoma
found_in:
- Synovial_Sarcoma-deep-research-falcon.md
findings:
- statement: Synovial sarcoma (SyS) is a rare aggressive soft tissue sarcoma carrying the chromosomal translocation t(X;18), encoding the fusion transcript SS18::SSX.
supporting_text: Synovial sarcoma (SyS) is a rare aggressive soft tissue sarcoma carrying the chromosomal translocation t(X;18), encoding the fusion transcript SS18::SSX.
evidence:
- reference: DOI:10.3390/cancers15153887
reference_title: Innovative Breakthroughs for the Treatment of Advanced and Metastatic Synovial Sarcoma
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Synovial sarcoma (SyS) is a rare aggressive soft tissue sarcoma carrying the chromosomal translocation t(X;18), encoding the fusion transcript SS18::SSX.
explanation: Deep research cited this publication as relevant literature for Synovial Sarcoma.
- reference: DOI:10.3390/cancers15194860
title: 'Synovial Sarcoma in the Extremity: Diversity of Imaging Features for Diagnosis and Prognosis'
found_in:
- Synovial_Sarcoma-deep-research-falcon.md
findings:
- statement: Synovial sarcomas are rare and highly aggressive soft-tissue sarcomas, primarily affecting adolescents and young adults aged 15–40 years.
supporting_text: Synovial sarcomas are rare and highly aggressive soft-tissue sarcomas, primarily affecting adolescents and young adults aged 15–40 years.
evidence:
- reference: DOI:10.3390/cancers15194860
reference_title: 'Synovial Sarcoma in the Extremity: Diversity of Imaging Features for Diagnosis and Prognosis'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Synovial sarcomas are rare and highly aggressive soft-tissue sarcomas, primarily affecting adolescents and young adults aged 15–40 years.
explanation: Deep research cited this publication as relevant literature for Synovial Sarcoma.
- reference: DOI:10.3390/cells13201695
title: Genetic and Molecular Heterogeneity of Synovial Sarcoma and Associated Challenges in Therapy
found_in:
- Synovial_Sarcoma-deep-research-falcon.md
findings:
- statement: Synovial sarcoma (SS) is one of the most common types of pediatric soft tissue sarcoma (STS) being far less frequent in adults.
supporting_text: Synovial sarcoma (SS) is one of the most common types of pediatric soft tissue sarcoma (STS) being far less frequent in adults.
evidence:
- reference: DOI:10.3390/cells13201695
reference_title: Genetic and Molecular Heterogeneity of Synovial Sarcoma and Associated Challenges in Therapy
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Synovial sarcoma (SS) is one of the most common types of pediatric soft tissue sarcoma (STS) being far less frequent in adults.
explanation: Deep research cited this publication as relevant literature for Synovial Sarcoma.
- reference: DOI:10.3390/jpm15100455
title: Molecular Profiling of SYT-SSX Fusion Transcripts for Enhanced Diagnosis of Synovial Sarcomas
found_in:
- Synovial_Sarcoma-deep-research-falcon.md
findings:
- statement: Synovial sarcoma (SS) is an aggressive soft-tissue tumor characterized by the chromosomal translocation t(X;18) (p11.2;q11.2), most commonly involving the fusion of the SYT gene on chromosome 18 with the SSX1 or SSX2 genes on chromosome X.
supporting_text: Synovial sarcoma (SS) is an aggressive soft-tissue tumor characterized by the chromosomal translocation t(X;18) (p11.2;q11.2), most commonly involving the fusion of the SYT gene on chromosome 18 with the SSX1 or SSX2 genes on chromosome X.
evidence:
- reference: DOI:10.3390/jpm15100455
reference_title: Molecular Profiling of SYT-SSX Fusion Transcripts for Enhanced Diagnosis of Synovial Sarcomas
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: Synovial sarcoma (SS) is an aggressive soft-tissue tumor characterized by the chromosomal translocation t(X;18) (p11.2;q11.2), most commonly involving the fusion of the SYT gene on chromosome 18 with the SSX1 or SSX2 genes on chromosome X.
explanation: Deep research cited this publication as relevant literature for Synovial Sarcoma.
- reference: DOI:10.35630/2025/15/2.211
title: 'SYNOVIAL SARCOMA AMONG ADULTS: FROM EPIDEMIOLOGY TO CLINICAL PRESENTATION, CURRENT DIAGNOSTIC STANDARDS, TREATMENT METHODS AND PROGNOSIS'
found_in:
- Synovial_Sarcoma-deep-research-falcon.md
findings:
- statement: 'SYNOVIAL SARCOMA AMONG ADULTS: FROM EPIDEMIOLOGY TO CLINICAL PRESENTATION, CURRENT DIAGNOSTIC STANDARDS, TREATMENT METHODS AND PROGNOSIS'
supporting_text: This article aims to comprehensively analyse the available literature on synovial sarcoma (SS), focusing on its pathogenesis, epidemiology, clinical presentation, diagnostic strategies, treatment approaches, and emerging therapeutic research.
evidence:
- reference: DOI:10.35630/2025/15/2.211
reference_title: 'SYNOVIAL SARCOMA AMONG ADULTS: FROM EPIDEMIOLOGY TO CLINICAL PRESENTATION, CURRENT DIAGNOSTIC STANDARDS, TREATMENT METHODS AND PROGNOSIS'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: This article aims to comprehensively analyse the available literature on synovial sarcoma (SS), focusing on its pathogenesis, epidemiology, clinical presentation, diagnostic strategies, treatment approaches, and emerging therapeutic research.
explanation: Deep research cited this publication as relevant literature for Synovial Sarcoma.
Synovial sarcoma is a rare, aggressive soft-tissue sarcoma that typically arises in deep soft tissues (often of extremities) in adolescents and young adults, and is defined molecularly by the pathognomonic chromosomal translocation t(X;18) producing an SS18::SSX fusion oncoprotein. (lesovaya2024geneticandmolecular pages 1-2, ferrari2023treatmentatrelapse pages 1-2)
A contemporary review summarizes SS as a WHO-recognized spindle-cell sarcoma that can show epithelial differentiation, emphasizing that the SS18::SSX fusion is a key diagnostic identifier. (lesovaya2024geneticandmolecular pages 1-2)
Common synonyms/aliases and related terminology include: - Synovial sarcoma, SS, SyS (lesovaya2024geneticandmolecular pages 1-2, ferrari2023treatmentatrelapse pages 1-2) - SYT-SSX (older name for SS18::SSX) (ferrari2023treatmentatrelapse pages 1-2, louati2025molecularprofilingof pages 12-14) - SS18-SSX (hyphenated form; also written SS18::SSX) (baranov2020anovelss18ssx pages 1-2)
The retrieved full-text evidence did not include explicit codes for OMIM, Orphanet, ICD-10/ICD-11, MeSH, or MONDO, so these are reported as not found in gathered sources rather than guessed.
The information in this report is derived from: - Aggregated disease-level resources: peer-reviewed reviews and registry/SEER-derived survival analyses (lesovaya2024geneticandmolecular pages 1-2, ferrari2023treatmentatrelapse pages 1-2, bulski2025synovialsarcomaamong pages 6-7) - Primary molecular/pathology studies: diagnostic antibody validation and mechanistic epigenetics work (baranov2020anovelss18ssx pages 1-2, benabdallah2023aberrantgeneactivation pages 1-2)
Causal genetic event (somatic): Synovial sarcoma is driven by the t(X;18) translocation producing an SS18::SSX fusion (most often SSX1 or SSX2, rarely SSX4). (ferrari2023treatmentatrelapse pages 1-2, baranov2020anovelss18ssx pages 1-2)
Mechanistic causal model (current understanding): The fusion oncoprotein acts primarily through chromatin and transcriptional reprogramming, notably through interactions with BAF/SWI–SNF chromatin-remodeling complexes and Polycomb-associated chromatin. (landuzzi2023innovativebreakthroughsfor pages 1-2, benabdallah2023aberrantgeneactivation pages 1-2)
Direct abstract support (primary study): Benabdallah et al. (Nature Structural & Molecular Biology; published online 2023-09-21) states: “The SS18-SSX fusion drives oncogenic transformation in synovial sarcoma by bridging SS18, a member of the mSWI/SNF (BAF) complex, to Polycomb repressive complex 1 (PRC1) target genes.” (benabdallah2023aberrantgeneactivation pages 1-2)
Demographic associations (epidemiologic risk context): SS is most frequently diagnosed in adolescents and young adults (e.g., 15–35 or 15–40 years) with a slight male predominance reported in reviews. (lesovaya2024geneticandmolecular pages 1-2, ferrari2023treatmentatrelapse pages 1-2)
Environmental/lifestyle/infectious risks: No specific, well-supported environmental or infectious causal exposures were identified in the retrieved evidence.
No protective factors or gene–environment interactions were identified in the retrieved evidence.
A large pediatric/AYA-focused review describes SS as typically presenting as a “painless, gradually enlarging soft-tissue mass,” most commonly in the extremities. (ferrari2023treatmentatrelapse pages 1-2)
Common primary sites: - Extremities are most common (e.g., ~66% extremities in one review; ~80% extremities in another review). (lesovaya2024geneticandmolecular pages 1-2, ferrari2023treatmentatrelapse pages 1-2)
Metastatic presentation: - <10% present with metastases at diagnosis; lung is the most common metastatic site. (ferrari2023treatmentatrelapse pages 1-2)
A 2023 imaging review emphasizes that imaging can appear non-aggressive early (leading to misclassification), but characteristic MRI/CT patterns exist and may have prognostic value. Its summary tables report classic signs (e.g., “triple sign,” “bowl of grapes”) and note that calcification occurs in up to ~30% of cases; they also list imaging features associated with poor prognosis (e.g., hemorrhage/fluid–fluid levels, intercompartmental extension) and comparatively favorable prognosis (calcification). (cho2023synovialsarcomain media 393c0cbc, cho2023synovialsarcomain media 0aa1424d)
Histologic subtypes include monophasic and biphasic variants (and poorly differentiated in some series), and SS can show epithelial differentiation consistent with its biphasic morphology. (lesovaya2024geneticandmolecular pages 1-2, ferrari2023treatmentatrelapse pages 1-2)
(These are ontology suggestions; frequencies vary by cohort and were not systematically quantified in the retrieved evidence.)
Quality-of-life (QoL) impacts were not quantitatively extracted from the retrieved sources; however, SS is described as aggressive and management frequently requires multimodal therapy, which typically has substantial functional/QoL implications (surgery, radiotherapy, chemotherapy). (ferrari2023treatmentatrelapse pages 1-2, bulski2025synovialsarcomaamong pages 6-7)
The 2020 AJSP antibody-development paper explicitly frames SS as characterized by t(X;18) producing SS18-SSX rearrangements and variants, and notes diagnostic challenges due to overlap with other tumor types. (baranov2020anovelss18ssx pages 1-2)
For SS, the key “variant” is the structural rearrangement generating the SS18::SSX fusion transcript (structural variant). (ferrari2023treatmentatrelapse pages 1-2, baranov2020anovelss18ssx pages 1-2)
Multiple 2023–2024/2025 sources emphasize that SS18::SSX causes genome-wide epigenetic deregulation via altered chromatin complex targeting and stability, rather than a high burden of recurrent point mutations. (landuzzi2023innovativebreakthroughsfor pages 1-2, benabdallah2023aberrantgeneactivation pages 1-2)
Benabdallah et al. (2023) provide a mechanistic model in which PRC1.1-mediated H2AK119ub1 supports SS18-SSX chromatin occupancy, and the SSX C-terminus stabilizes PRC1.1 to increase H2AK119ub1, creating high H2AK119ub1 levels in murine and human SS. (benabdallah2023aberrantgeneactivation pages 1-2)
No specific environmental toxins, lifestyle exposures, or infectious triggers were identified in the retrieved evidence as established causal contributors.
Upstream initiating event: Somatic chromosomal translocation t(X;18) → expression of SS18::SSX fusion oncoprotein. (ferrari2023treatmentatrelapse pages 1-2, baranov2020anovelss18ssx pages 1-2)
Primary mechanistic class: Chromatin remodeling / epigenetic reprogramming: - SS18::SSX retargets transcription by interfacing with mSWI/SNF (BAF) and Polycomb biology (PRC1.1, H2AK119ub1). (benabdallah2023aberrantgeneactivation pages 1-2)
Transcriptional/pathway consequences: Multiple downstream pathways are implicated in proliferation, survival, and metastatic phenotypes: - Wnt/β-catenin and YAP/TAZ–TEAD activation are described as common patterns and interacting programs in SS. (lesovaya2024geneticandmolecular pages 5-6) - Apoptosis evasion may occur through kinase/transcriptional axes that increase anti-apoptotic gene expression (e.g., TYK2→STAT3→BCL2 axis described as a mechanism of apoptosis evasion, with SS18-SSX enhancing TYK2 transcription). (lesovaya2024geneticandmolecular pages 5-6)
Benabdallah et al. (2023) emphasize that PRC1.1 is the main depositor of H2AK119ub1 required for SS18-SSX occupancy and that SSX-C increases PRC1.1 stability: “Variant Polycomb repressive complex 1.1 (PRC1.1) acts as the main depositor of H2AK119ub1 and is therefore required for SS18-SSX occupancy.” (benabdallah2023aberrantgeneactivation pages 1-2)
SS frequently expresses cancer-testis antigens such as NY-ESO-1, MAGE-A4, and PRAME, supporting engineered TCR-T strategies; at the same time, SS is often described as relatively “immune cold,” motivating combination or microenvironment-modifying strategies. (lesovaya2024geneticandmolecular pages 5-6, wang2025molecularandepigenetic pages 7-8)
GO Biological Process (examples): - Chromatin remodeling - Histone ubiquitination (related to H2AK119ub1 biology) - Transcriptional regulation - Wnt signaling pathway - Regulation of apoptotic process
CL Cell types (examples): - Fibroblast (often discussed in cell-of-origin contexts for SS) - Tumor-infiltrating lymphocyte / T cell (for immunotherapy contexts) - Endothelial cell (angiogenesis/TKI contexts)
(These are ontology suggestions; the exact mappings depend on the evidence model used.)
Primary disease burden is in deep soft tissues, most frequently extremities. (lesovaya2024geneticandmolecular pages 1-2, ferrari2023treatmentatrelapse pages 1-2)
Common metastatic site: lung. (ferrari2023treatmentatrelapse pages 1-2)
SS frequently affects adolescents/young adults and may have an indolent-appearing early course on imaging, contributing to diagnostic delay and misclassification as benign. (cho2023synovialsarcomain media 393c0cbc, cho2023synovialsarcomain media 0aa1424d)
Localized disease can be controlled with multimodal therapy, but relapse/metastasis remains a major clinical problem; outcomes after relapse are described as poor and relapse treatment is often individualized. (ferrari2023treatmentatrelapse pages 1-2)
A 2023 review reports annual incidence of approximately 0.8 per million in children and 1.4 per million in adults. (ferrari2023treatmentatrelapse pages 1-2)
Age distribution: reviews describe peak diagnosis in adolescents and young adults (e.g., ~15–35 or 15–40). (lesovaya2024geneticandmolecular pages 1-2, cho2023synovialsarcomain media 393c0cbc)
SS is not presented as an inherited Mendelian disorder in the retrieved evidence; its hallmark event is a somatic fusion translocation. (baranov2020anovelss18ssx pages 1-2)
A key advance is fusion-specific IHC using SS18::SSX neoepitope antibodies.
Primary study evidence (Baranov et al., AJSP 2020; DOI: https://doi.org/10.1097/PAS.0000000000001447; publication month: 2020-03): - The abstract reports “strong diffuse nuclear staining in 95 of 100 (95%) SS cases, whereas none of the 300 control tumors showed any staining” for the SS18-SSX fusion-specific antibody, and indicates SSX C-terminus staining in all 100 SS cases with some off-target positivity among controls. (baranov2020anovelss18ssx pages 1-2)
Clinical implication: fusion-specific IHC can reduce reliance on FISH/RT-PCR in many cases, while molecular testing remains important for unusual patterns or equivocal cases. (baranov2020anovelss18ssx pages 1-2)
SS can overlap morphologically and immunophenotypically with other sarcomas and carcinomas; IHC markers like TLE1 are helpful but not perfectly specific, supporting continued use of confirmatory molecular testing in challenging cases. (louati2025molecularprofilingof pages 12-14, baranov2020anovelss18ssx pages 1-2)
A 2025 review summarizing SEER-derived survival reports survival estimates including 1-, 5-, 10-, and 20-year survival rates of 87.3%, 59.4%, 50.8%, and 42.8%, with median overall survival ~138 months; it also notes worse outcomes with metastatic disease at diagnosis and larger tumors, as well as differences by histologic subtype and age. (bulski2025synovialsarcomaamong pages 6-7)
Key prognostic factors reported across reviews include: - Tumor size, margin status/completeness of resection, site, and metastasis at diagnosis. (ferrari2023treatmentatrelapse pages 1-2, bulski2025synovialsarcomaamong pages 6-7) - Imaging-associated adverse indicators (triple sign; bowl-of-grapes; hemorrhage/fluid–fluid levels; intercompartmental extension; peritumoral enhancement), with calcification associated with more favorable outcomes in the imaging review’s prognostic table. (cho2023synovialsarcomain media 0aa1424d)
Suggested MAXO terms (examples): - Surgical excision of tumor - External beam radiotherapy - Anthracycline-based chemotherapy - Ifosfamide therapy
A 2025 expert review summarizing SPEARHEAD-1 reports that MAGE-A4-directed engineered TCR therapy afamitresgene autoleucel achieved an objective response rate (ORR) of ~43% with median duration of response ~6 months in advanced synovial sarcoma, and ties this to regulatory approval in the appropriate HLA/antigen context. (wang2025molecularandepigenetic pages 7-8)
Rationale for target selection: SS expresses cancer-testis antigens including MAGE-A4, NY-ESO-1, and PRAME, enabling antigen-directed cellular therapies. (lesovaya2024geneticandmolecular pages 5-6, wang2025molecularandepigenetic pages 7-8)
A 2023 review highlights that improved understanding of SS molecular biology has enabled exploration of newer modalities including PROTAC degraders and other approaches aimed at chromatin/transcriptional dependencies driven by SS18::SSX. (landuzzi2023innovativebreakthroughsfor pages 1-2)
Mechanistic work identifying PRC1.1/H2AK119ub1 as required for SS18-SSX occupancy provides a rationale for therapeutically targeting Polycomb/chromatin dependencies. (benabdallah2023aberrantgeneactivation pages 1-2)
Recent reviews describe ongoing investigation of multikinase inhibitors and other targeted agents in SS, with pazopanib often cited in practice-oriented summaries and additional TKIs under study. (lesovaya2024geneticandmolecular pages 5-6)
No established primary prevention strategy is supported by the retrieved evidence. Practical “prevention” is best interpreted as: - Secondary prevention: early recognition of suspicious soft-tissue masses and timely biopsy/molecular testing to avoid misdiagnosis and delay. (cho2023synovialsarcomain media 393c0cbc, cho2023synovialsarcomain media 0aa1424d) - Tertiary prevention: guideline-based multimodal management and surveillance for recurrence/metastasis.
Naturally occurring synovial sarcoma in other species was not identified in the retrieved evidence.
A 2023 review details that SS preclinical modeling includes: - Conditional transgenic mouse models expressing SS18::SSX that can develop SS, sometimes in combination with cooperating alterations (e.g., BCL2, Wnt/β-catenin, FGFR, PTEN loss, SMARCB1 loss). (landuzzi2023innovativebreakthroughsfor pages 1-2) - Patient-derived xenografts (PDX) and cell line-derived xenografts.
These models are used to discover vulnerabilities and develop epigenetic and immunotherapeutic strategies. (landuzzi2023innovativebreakthroughsfor pages 1-2)
The following table is designed for rapid knowledge-base ingestion.
| Domain | Key facts |
|---|---|
| Identifiers / classification | • Rare malignant soft-tissue sarcoma; WHO-recognized mesenchymal spindle-cell tumor that may show epithelial differentiation. • Common aliases include synovial sarcoma, SyS, SS, and older fusion terminology SYT-SSX / SS18-SSX. • MONDO/ICD/Orphanet/OMIM specific codes: not found in gathered sources. (lesovaya2024geneticandmolecular pages 1-2, ferrari2023treatmentatrelapse pages 1-2, landuzzi2023innovativebreakthroughsfor pages 1-2) |
| Core genetic driver | • Pathognomonic t(X;18)(p11;q11) creates SS18::SSX fusion, most often SSX1 or SSX2 and rarely SSX4. • Fusion is present in >90–95% of cases and is the central diagnostic/molecular hallmark. • SS18::SSX perturbs chromatin-remodeling machinery rather than acting as a classic kinase driver. (ferrari2023treatmentatrelapse pages 1-2, baranov2020anovelss18ssx pages 1-2, benabdallah2023aberrantgeneactivation pages 1-2) |
| Epidemiology | • Accounts for ~8–10% of soft tissue sarcomas in some series/reviews; one review cites 4–10% of STS subtypes. • Incidence is ~0.8 per million/year in children and ~1.4 per million/year in adults; U.S. incidence ~1.42 per million has also been reported. • Predominantly affects adolescents and young adults, especially ages 15–40/15–35; slight male predominance. (lesovaya2024geneticandmolecular pages 1-2, ferrari2023treatmentatrelapse pages 1-2, bulski2025synovialsarcomaamong pages 6-7) |
| Typical presentation / anatomical sites | • Usually presents as a painless, slowly enlarging deep soft-tissue mass. • Extremities are the dominant site: ~66% in one review; ~80% in soft tissues of extremities in another; near large joints is typical but not required. • Metastases are present in <10% at diagnosis, most commonly to lung. (lesovaya2024geneticandmolecular pages 1-2, ferrari2023treatmentatrelapse pages 1-2, cho2023synovialsarcomain media 393c0cbc) |
| Diagnostics | • Diagnosis relies on biopsy plus molecular confirmation by FISH, RT-PCR, or targeted RNA sequencing for SS18 rearrangement / SS18::SSX transcript. • Fusion-specific IHC is highly useful: E9X9V SS18-SSX antibody showed 95% sensitivity and 100% specificity in a 2020 AJSP study; SSX C-terminus antibody was 100% sensitive but less specific. • TLE1 is useful but imperfectly specific, so unusual cases should trigger molecular testing. (baranov2020anovelss18ssx pages 1-2, qiu2024primaryrenalsynovial pages 6-6, louati2025molecularprofilingof pages 12-14) |
| Prognostic factors | • Worse prognosis is associated with older age, larger tumor size, metastatic disease at diagnosis, higher grade, non-extremity/axial sites, and incomplete resection/positive margins. • Radiologic adverse indicators include triple sign, bowl-of-grapes appearance, hemorrhage/fluid-fluid levels, intercompartment extension, and lack of calcification; calcification can be relatively favorable. • Reported survival estimates include median OS ~138 months in SEER-based analysis and 5-year survival roughly 59–71% across broad cohorts. (bulski2025synovialsarcomaamong pages 6-7, cho2023synovialsarcomain media 393c0cbc, cho2023synovialsarcomain media 0aa1424d) |
| Standard treatment | • Localized disease: wide surgical resection is the mainstay. • Radiotherapy is commonly used for larger tumors, high-grade tumors, or positive/close margins; chemotherapy is considered for high-risk localized or advanced disease. • Advanced/metastatic disease is typically treated with anthracycline-based chemotherapy, often with ifosfamide; later-line options include trabectedin and pazopanib. (fuchs2023emergingtargetedand pages 7-8, bulski2025synovialsarcomaamong pages 6-7, lesovaya2024geneticandmolecular pages 5-6) |
| Emerging therapies 2023–2024 | • Engineered TCR-T therapies targeting cancer-testis antigens are the major advance: MAGE-A4-targeted afamitresgene autoleucel showed ORR ~43% with median response duration ~6 months in SPEARHEAD-1. • NY-ESO-1-, PRAME-, and MAGE-A4-directed TCR approaches remain active areas of development; eligibility depends on antigen expression and HLA type. • Additional investigational strategies include multikinase TKIs (e.g., regorafenib, anlotinib, TAS-115), BRD9/BAF-directed approaches, HDAC/EZH2-directed epigenetic therapy, and combination immune strategies. (wang2025molecularandepigenetic pages 6-7, lesovaya2024geneticandmolecular pages 5-6, wang2025molecularandepigenetic pages 7-8) |
| Key mechanistic pathways / epigenetics | • SS18::SSX rewires BAF/SWI-SNF chromatin complexes and links to Polycomb biology; PRC1.1-mediated H2AK119ub1 deposition is required for fusion occupancy, and the SSX C-terminus increases PRC1.1 stability. • Additional implicated pathways include Wnt/β-catenin, YAP/TAZ-TEAD, CREB/CDK9, and TYK2→STAT3→BCL2 apoptosis-evasion signaling. • Tumors frequently express cancer-testis antigens such as NY-ESO-1, MAGE-A4, and PRAME, while often exhibiting an immune-cold microenvironment. (benabdallah2023aberrantgeneactivation pages 1-2, lesovaya2024geneticandmolecular pages 5-6, wang2025molecularandepigenetic pages 6-7) |
| Model systems | • Available preclinical systems include conditional transgenic mouse models expressing SS18::SSX, synovial sarcoma cell lines, cell line-derived xenografts, and patient-derived xenografts. • Mouse models have been combined with alterations such as BCL2 gain, Wnt/β-catenin activation, FGFR changes, PTEN loss, or SMARCB1 loss to study sarcomagenesis. • These models are used to identify vulnerabilities in chromatin regulation, immune targeting, and combination therapy. (landuzzi2023innovativebreakthroughsfor pages 1-2, benabdallah2023aberrantgeneactivation pages 1-2) |
Table: This table summarizes high-yield knowledge-base facts on synovial sarcoma across genetics, epidemiology, presentation, diagnosis, prognosis, treatment, mechanisms, and models. It is designed for rapid curation and includes only findings supported by gathered citation contexts.
References
(lesovaya2024geneticandmolecular pages 1-2): Ekaterina A. Lesovaya, Timur I. Fetisov, Beniamin Yu. Bokhyan, Varvara P. Maksimova, Evgeny P. Kulikov, Gennady A. Belitsky, Kirill I. Kirsanov, and Marianna G. Yakubovskaya. Genetic and molecular heterogeneity of synovial sarcoma and associated challenges in therapy. Cells, 13:1695, Oct 2024. URL: https://doi.org/10.3390/cells13201695, doi:10.3390/cells13201695. This article has 16 citations.
(ferrari2023treatmentatrelapse pages 1-2): Andrea Ferrari, Pablo Berlanga, Susanne Andrea Gatz, Reineke A Schoot, Max M van Noesel, Shushan Hovsepyan, Stefano Chiaravalli, Luca Bergamaschi, Veronique Minard-Colin, Nadege Corradini, Rita Alaggio, Patrizia Gasparini, Bernadette Brennan, Michela Casanova, Sandro Pasquali, and Daniel Orbach. Treatment at relapse for synovial sarcoma of children, adolescents and young adults: from the state of art to future clinical perspectives. Cancer Management and Research, 15:1183-1196, Oct 2023. URL: https://doi.org/10.2147/cmar.s404371, doi:10.2147/cmar.s404371. This article has 8 citations and is from a peer-reviewed journal.
(louati2025molecularprofilingof pages 12-14): Sara Louati, Kaoutar Bentayebi, Ibtissam Saad, Yvonne Gloor, Nadia Senhaji, Abdelmajid Elmrini, Lahcen Belyamani, Rachid Eljaoudi, Marc Ansari, Sanae Bennis, and Youssef Daali. Molecular profiling of syt-ssx fusion transcripts for enhanced diagnosis of synovial sarcomas. Journal of Personalized Medicine, 15:455, Sep 2025. URL: https://doi.org/10.3390/jpm15100455, doi:10.3390/jpm15100455. This article has 0 citations.
(baranov2020anovelss18ssx pages 1-2): Esther Baranov, Matthew J. McBride, Andrew M. Bellizzi, Azra H. Ligon, Christopher D.M. Fletcher, Cigall Kadoch, and Jason L. Hornick. A novel ss18-ssx fusion-specific antibody for the diagnosis of synovial sarcoma. The American Journal of Surgical Pathology, 44:922-933, Mar 2020. URL: https://doi.org/10.1097/pas.0000000000001447, doi:10.1097/pas.0000000000001447. This article has 234 citations.
(bulski2025synovialsarcomaamong pages 6-7): Jakub Bulski, Filip Maj, Karol Sornat, Agata Estreicher, Anna Klasa, Aleksandra Sobaś, Kamil Biedka, Oliwia Ziobro, and Katarzyna Błaszczyk. Synovial sarcoma among adults: from epidemiology to clinical presentation, current diagnostic standards, treatment methods and prognosis. Archiv Euromedica, Apr 2025. URL: https://doi.org/10.35630/2025/15/2.211, doi:10.35630/2025/15/2.211. This article has 0 citations.
(benabdallah2023aberrantgeneactivation pages 1-2): Nezha S. Benabdallah, Vineet Dalal, R. Wilder Scott, Fady Marcous, Afroditi Sotiriou, Felix K. F. Kommoss, Anastasija Pejkovska, Ludmila Gaspar, Lena Wagner, Francisco J. Sánchez-Rivera, Monica Ta, Shelby Thornton, Torsten O. Nielsen, T. Michael Underhill, and Ana Banito. Aberrant gene activation in synovial sarcoma relies on ssx specificity and increased prc1.1 stability. Nature Structural & Molecular Biology, 30:1640-1652, Sep 2023. URL: https://doi.org/10.1038/s41594-023-01096-3, doi:10.1038/s41594-023-01096-3. This article has 35 citations and is from a highest quality peer-reviewed journal.
(landuzzi2023innovativebreakthroughsfor pages 1-2): Lorena Landuzzi, Maria Cristina Manara, Laura Pazzaglia, Pier-Luigi Lollini, and Katia Scotlandi. Innovative breakthroughs for the treatment of advanced and metastatic synovial sarcoma. Cancers, 15:3887, Jul 2023. URL: https://doi.org/10.3390/cancers15153887, doi:10.3390/cancers15153887. This article has 17 citations.
(cho2023synovialsarcomain media 393c0cbc): Eun Byul Cho, Seul Ki Lee, Jee-Young Kim, and Yuri Kim. Synovial sarcoma in the extremity: diversity of imaging features for diagnosis and prognosis. Cancers, 15:4860, Oct 2023. URL: https://doi.org/10.3390/cancers15194860, doi:10.3390/cancers15194860. This article has 34 citations.
(cho2023synovialsarcomain media 0aa1424d): Eun Byul Cho, Seul Ki Lee, Jee-Young Kim, and Yuri Kim. Synovial sarcoma in the extremity: diversity of imaging features for diagnosis and prognosis. Cancers, 15:4860, Oct 2023. URL: https://doi.org/10.3390/cancers15194860, doi:10.3390/cancers15194860. This article has 34 citations.
(lesovaya2024geneticandmolecular pages 5-6): Ekaterina A. Lesovaya, Timur I. Fetisov, Beniamin Yu. Bokhyan, Varvara P. Maksimova, Evgeny P. Kulikov, Gennady A. Belitsky, Kirill I. Kirsanov, and Marianna G. Yakubovskaya. Genetic and molecular heterogeneity of synovial sarcoma and associated challenges in therapy. Cells, 13:1695, Oct 2024. URL: https://doi.org/10.3390/cells13201695, doi:10.3390/cells13201695. This article has 16 citations.
(wang2025molecularandepigenetic pages 7-8): Amy Xueqi Wang, Kevin B. Jones, and Torsten O. Nielsen. Molecular and epigenetic oncogenesis in synovial sarcoma: implications for cancer biology, diagnosis and treatment. Oncogene, 44:3527-3536, Aug 2025. URL: https://doi.org/10.1038/s41388-025-03547-1, doi:10.1038/s41388-025-03547-1. This article has 4 citations and is from a domain leading peer-reviewed journal.
(qiu2024primaryrenalsynovial pages 6-6): Hong Qiu, Zhaorong Tang, and Dan Nie. Primary renal synovial sarcomas diagnosed by a novel fusion gene with the fusion site involving exons of ss18 and ssx2: a case report. Oncologie, 26:679-685, May 2024. URL: https://doi.org/10.1515/oncologie-2024-0101, doi:10.1515/oncologie-2024-0101. This article has 2 citations and is from a peer-reviewed journal.
(fuchs2023emergingtargetedand pages 7-8): Joseph R. Fuchs, Brian C. Schulte, Jeffrey W. Fuchs, and Mark Agulnik. Emerging targeted and cellular therapies in the treatment of advanced and metastatic synovial sarcoma. Frontiers in Oncology, Jan 2023. URL: https://doi.org/10.3389/fonc.2023.1123464, doi:10.3389/fonc.2023.1123464. This article has 16 citations.
(wang2025molecularandepigenetic pages 6-7): Amy Xueqi Wang, Kevin B. Jones, and Torsten O. Nielsen. Molecular and epigenetic oncogenesis in synovial sarcoma: implications for cancer biology, diagnosis and treatment. Oncogene, 44:3527-3536, Aug 2025. URL: https://doi.org/10.1038/s41388-025-03547-1, doi:10.1038/s41388-025-03547-1. This article has 4 citations and is from a domain leading peer-reviewed journal.
(wang2025molecularandepigenetic pages 1-2): Amy Xueqi Wang, Kevin B. Jones, and Torsten O. Nielsen. Molecular and epigenetic oncogenesis in synovial sarcoma: implications for cancer biology, diagnosis and treatment. Oncogene, 44:3527-3536, Aug 2025. URL: https://doi.org/10.1038/s41388-025-03547-1, doi:10.1038/s41388-025-03547-1. This article has 4 citations and is from a domain leading peer-reviewed journal.