# 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)

## 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

- 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/)
- cancers: [Sarcomas (soft tissue, bone, GIST)](https://onco.cc/cancers/sarcoma/)

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