Rapid and Complete Response to Combination Anti-CTLA-4 and Anti-PD-1 Checkpoint Inhibitor Therapy in a Patient With Stage IV Refractory End-stage Epithelioid Sarcoma: A Case Report

Epithelioid sarcoma, in the relapse-refractory setting, has limited expected survival. SMARCB1 inactivation, common in epithelioid sarcoma, causes loss of INI1 protein expression and overexpression of the cancer cell growth promoting methyltransferase enzyme, EZH2. We treated a 19-year-old male with stage IV SMARCB1 inactivated epithelioid sarcoma presenting with recurrent end stage (Eastern Cooperative Oncology Group Performance Status 4) rapidly progressing bulky disease with combination ipilimumab and nivolumab. He failed standard therapy and an EZH2 inhibitor (tazemetostat). He presented (May 13, 2019) with a large (16.1×18.6 cm) soft tissue back mass extending from T10 to L3. Complete clinical regression of the back mass occurred within 2 weeks (May 28, 2019) of cycle 1 of combined checkpoint inhibition therapy followed by a positron emission tomography-negative complete remission (October 11, 2019). After a second negative positron emission tomography/computed tomography scan (January 13, 2020), checkpoint inhibition therapy was discontinued. He has returned to normal activities with a normal physical examination and Eastern Cooperative Oncology Group Performance Status of 0 at his last visit (June 29, 2020). In conclusion, combined checkpoint inhibition therapy warrants further study in the salvage setting in patients with epithelioid and other INI1 protein-deficient sarcomas seemingly regardless of prior therapy, extent of disease, and performance status.