# Synovial sarcoma

Source: https://onco.cc/cancers/synovial-sarcoma/  
OnCo record `synovial-sarcoma` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Synovial sarcoma is a young person's sarcoma driven by a single fusion gene, SS18-SSX, that scrambles how genes are switched on. It is treated with surgery, radiotherapy and ifosfamide-based chemotherapy, and in 2024 it became the first solid tumour with an approved engineered T-cell receptor therapy.

## Summary

Synovial sarcoma has nothing to do with the synovium; it is defined by the SS18-SSX fusion, which hijacks the BAF chromatin remodelling complex. It presents as a slow-growing deep mass near the knee, ankle or other joints in people aged 15 to 40, and is graded high by default. Treatment is wide resection with radiotherapy, and chemotherapy with ifosfamide and doxorubicin is used more readily than in other sarcomas because responses are frequent, including in the neoadjuvant setting; pazopanib and trabectedin have activity in advanced disease. Most tumours express the cancer-testis antigens MAGE-A4 and NY-ESO-1, and afamitresgene autoleucel, a MAGE-A4-directed T-cell receptor therapy, was approved in the United States in 2024 for advanced disease in HLA-A*02 patients, with letetresgene autoleucel against NY-ESO-1 following in trials.

## Fields

- Kind: Cancer
- Last checked: 2026-09-17
- Also known as: SS18-SSX sarcoma
- Tags: subtype-page
- Group: sarcoma
- Burden: Five to ten percent of soft-tissue sarcomas, typically in adolescents and young adults near the joints of the limbs; about half eventually metastasise, often to the lungs, and it is one of the few sarcomas where chemotherapy clearly helps.
- Subtypes: Monophasic synovial sarcoma; Biphasic synovial sarcoma; Poorly differentiated (round cell) synovial sarcoma
- Biomarkers: SS18-SSX fusion (FISH or RNA sequencing; SS18-SSX antibody); MAGE-A4 and NY-ESO-1 expression with HLA-A*02 typing (TCR therapy eligibility); Size over 5 cm and poorly differentiated component (prognosis)

## Sections of this record

The page is a hub with ten sections in reading order; large sections have their own page. The same plan as JSON: https://onco.cc/api/v1/cancers/synovial-sarcoma/sections.json

- Overview (on the hub): The TL;DR, the family this cancer belongs to, the organ, who gets it and what the state of the art is. https://onco.cc/cancers/synovial-sarcoma/#overview [3 state-of-the-art points]
- Types and stages (on the hub): Anatomy, the subtypes and how they differ, how it is staged, and where advanced disease spreads. https://onco.cc/cancers/synovial-sarcoma/#what-it-is [3 subtypes]
- Symptoms and diagnosis (on the hub): How this cancer shows itself, how the diagnosis is confirmed, and the biomarkers clinicians test for. https://onco.cc/cancers/synovial-sarcoma/#finding-it [3 biomarkers]
- Treatment (on the hub): The standard of care by setting, the medicines, surgery and radiotherapy named in it, and the regimens behind them. https://onco.cc/cancers/synovial-sarcoma/#treating-it [3 settings, 2 decisions with options]
- Trials and papers (on the hub): Trials recruiting now, the landmark trials, the trials held by this cancer's subtypes, the key papers and what they mean, the latest literature, and the milestones year by year. https://onco.cc/cancers/synovial-sarcoma/#evidence [3 trials, 5 key papers, 3 milestones]
- Biology and targets (on the hub): The molecular landscape: the targets and how often each appears, the pathways, the mechanics stages and the preclinical models. https://onco.cc/cancers/synovial-sarcoma/#science [8 targets]
- Countries and centres (own page): Cases by country, the UK and NHS pathway and other country lenses, the expert centres with trials on record, and the centres named on this cancer's subtypes. https://onco.cc/cancers/synovial-sarcoma/where-you-are/
- Decisions and support (on the hub): The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask. https://onco.cc/cancers/synovial-sarcoma/#living-with-it [15 questions, 6 red cards]
- Pipeline and open problems (own page): Everything in development, the medicines held by this cancer's subtypes, the open problems and what is being done about them, the roadmaps, and what changed on this record. https://onco.cc/cancers/synovial-sarcoma/coming/ [6 medicines, 3 trials, 3 open problems]
- Data (own page): Every connected record, the notes, the JSON, Markdown and RDF twins, and where the record came from and when it was checked. https://onco.cc/cancers/synovial-sarcoma/data/ [35 connected records]

## Standard of care

- Localised: Wide resection with pre- or postoperative radiotherapy; neoadjuvant or adjuvant ifosfamide-doxorubicin for large high-risk tumours. ([IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/), [Ifosfamide](https://onco.cc/drugs/ifosfamide/), [Doxorubicin](https://onco.cc/drugs/doxorubicin/))
- Advanced, first line: Ifosfamide-based chemotherapy, doxorubicin; pazopanib or trabectedin later. ([Ifosfamide](https://onco.cc/drugs/ifosfamide/), [Doxorubicin](https://onco.cc/drugs/doxorubicin/), [Pazopanib](https://onco.cc/drugs/pazopanib/), [Trabectedin](https://onco.cc/drugs/trabectedin/))
- Advanced, HLA-A*02 and MAGE-A4-positive: Afamitresgene autoleucel after chemotherapy; NY-ESO-1 TCR therapy in trials. ([Afamitresgene autoleucel](https://onco.cc/drugs/afamitresgene-autoleucel/))

## State of the art

- Afamitresgene autoleucel is the first T-cell receptor therapy approved for any solid tumour, with responses in about 40 percent of heavily pretreated patients.
- Chemosensitivity sets synovial sarcoma apart and justifies perioperative chemotherapy in high-risk cases.
- The single fusion driver makes it a model for epigenetic drugs such as BRD9 degraders.

## Open problems

- TCR therapy needs a matching HLA type and antigen, excluding most patients.
- Late lung metastases years after treatment.
- Fertility and growth in adolescent patients receiving chemotherapy.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Synovial_sarcoma
- Wikipedia: https://en.wikipedia.org/wiki/Synovial_sarcoma

## Connected records

- cancers: [Alveolar soft part sarcoma](https://onco.cc/cancers/alveolar-soft-part-sarcoma/), [Epithelioid sarcoma](https://onco.cc/cancers/epithelioid-sarcoma/), [Ewing sarcoma](https://onco.cc/cancers/ewing-sarcoma/), [Leiomyosarcoma](https://onco.cc/cancers/leiomyosarcoma/), [Liposarcoma](https://onco.cc/cancers/liposarcoma/), [Malignant peripheral nerve sheath tumour (MPNST)](https://onco.cc/cancers/malignant-peripheral-nerve-sheath-tumour/), [Rhabdomyosarcoma](https://onco.cc/cancers/rhabdomyosarcoma/), [Sarcomas (soft tissue, bone, GIST)](https://onco.cc/cancers/sarcoma/), [Soft tissue sarcoma of the extremity (localised and advanced)](https://onco.cc/cancers/extremity-soft-tissue-sarcoma/), [Undifferentiated pleomorphic sarcoma (UPS)](https://onco.cc/cancers/undifferentiated-pleomorphic-sarcoma/)
- key papers: [EORTC 62012: doxorubicin alone versus intensified doxorubicin plus ifosfamide for first-line treatment of advanced soft tissue sarcoma](https://onco.cc/key-papers/paper-eortc-62012-doxorubicin-ifosfamide-judson-lancet-oncol-2014/), [Identification of SYT and SSX, the genes fused by the t(X;18) translocation in synovial sarcoma](https://onco.cc/key-papers/paper-clark-syt-ssx-synovial-sarcoma-nat-genet-1994/), [ISG-STS 1001: histotype-tailored neoadjuvant chemotherapy versus standard chemotherapy in high-risk soft tissue sarcoma](https://onco.cc/key-papers/paper-isg-sts-1001-gronchi-lancet-oncol-2017/), [NY-ESO-1 c259 T-cell receptor therapy in synovial sarcoma: prolonged persistence and antitumour activity](https://onco.cc/key-papers/paper-dangelo-ny-eso-1-tcr-synovial-sarcoma-cancer-discov-2018/), [SPEARHEAD-1: afamitresgene autoleucel, the first engineered T-cell receptor therapy approved for a solid tumour, in synovial sarcoma](https://onco.cc/key-papers/paper-spearhead-1-lancet-2024/)
- drugs: [Afamitresgene autoleucel](https://onco.cc/drugs/afamitresgene-autoleucel/), [Doxorubicin](https://onco.cc/drugs/doxorubicin/), [Ifosfamide](https://onco.cc/drugs/ifosfamide/), [Letetresgene autoleucel](https://onco.cc/drugs/letetresgene-autoleucel/), [Pazopanib](https://onco.cc/drugs/pazopanib/), [Trabectedin](https://onco.cc/drugs/trabectedin/)
- technologies: [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/), [Methylation classifier for sarcomas](https://onco.cc/technologies/sarcoma-methylation-classifier/)
- terms: [SS18::SSX fusion (synovial sarcoma)](https://onco.cc/terms/ss18-ssx-fusion/)
- biomarkers: [HLA-A*02:01 (HLA typing for TCR therapies)](https://onco.cc/biomarkers/hla-a-02-01/)
- targets: [HLA-A](https://onco.cc/targets/hla-a/), [SMARCB1](https://onco.cc/targets/smarcb1/), [SS18](https://onco.cc/targets/ss18/), [SSX1](https://onco.cc/targets/ssx1/), [SSX2](https://onco.cc/targets/ssx2/)
- trials: [Multi-center Study of TBI-1301 (INN: Mipetresgene Autoleucel; Mip-cel) in Patients With NY-ESO-1 Positive Synovial Sarcoma](https://onco.cc/trials/nct07174427/), [Phase III Trial of Anlotinib, Catequentinib in Advanced Alveolar Soft Part Sarcoma, Leiomyosarcoma, Synovial Sarcoma (APROMISS)](https://onco.cc/trials/nct03016819/), [Spearhead 1 Study in Subjects With Advanced Synovial Sarcoma or Myxoid/Round Cell Liposarcoma](https://onco.cc/trials/nct04044768/)

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JSON: https://onco.cc/api/v1/entities/synovial-sarcoma.json