Synovial Sarcoma: Current Concepts and Future Perspectives

Abstract

Synovial sarcoma (SS) is a rare sarcoma driven by a translocation between SS18 and SSX 1, 2, or 4. With approximately 800 to 1,000 cases a year in the United States, it most commonly affects young adults between the ages of 15 and 30 years. The resultant tumors are either monophasic (pure sarcomas), biphasic (a combination or epithelioid and sarcomatous components), or poorly differentiated. The hybrid transcription factor SS18:SSX alters SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling and global methylation patterns that may allow for future therapeutic opportunities. In this review, we focus on the pharmacologic management of SS, both in the curative setting, where the standard approach is wide surgical excision combined with radiotherapy and/or (neo)adjuvant chemotherapy as appropriate, and in the palliative setting. In advanced disease, chemotherapy with anthracyclines and/or ifosfamide, trabectedin, or pazopanib has been demonstrated to be more active compared with other soft tissue sarcomas. In addition, a better understanding of the molecular and immunologic characteristics of SS has allowed for the identification of new potential targets and the development of novel biology-driven therapies that are all at different stages of testing. There include targeted agents, immunotherapy, and metabolic therapies. Because the impact of these strategies for improving SS outcome is still limited, current and future research is strongly needed to better understand the tumor biology, to identify predictive biomarkers, and to improve the outcomes for patients with SS.