Efficacy and safety of SHR-2554 in advanced epithelioid sarcoma: A phase 2 trial.

Abstract

11549 Background: Epithelioid sarcoma (ES) is a rare and aggressive subtype of soft-tissue sarcoma. The loss of SMARCB1 (INI1) expression which leads to oncogenic dependence on the transcriptional repressor EZH2 has been observed in over 90% of ES. Patients (pts) with metastatic ES have a poor prognosis. We investigated the efficacy and safety of SHR-2554, an oral selective EZH2 inhibitor, in pts with refractory ES. Methods: To be eligible for inclusion, pts had to fulfill the following criteria: 8 years or older; histologically confirmed advanced or metastatic ES with loss of INI1 or upregulated mRNA level of EZH2; progressive disease after at least one line of doxorubicin-containing chemotherapy; the presence of measurable disease according to RECIST 1.1; an ECOG performance status of 0-1. Pts received SHR2554 (350 mg, bid, po) until disease progression or unacceptable toxicity. The primary endpoint was progression-free rate at 12 weeks. A Simon two-stage design was applied. If there were 3 pts remaining progression-free at 12 weeks within the first 9 pts, the cohort would expand to 17 pts and the outcome would be positive if more than 7 pts remained progression-free at 12 weeks. Results: Between Jul 2021 and Dec 2023, a total of 17 pts were enrolled and received at least 1 dose of SHR-2554. The median age was 32 years (range 8-57) and 41.2% were males. 9 (52.9%) pts had received immunotherapy targeting PD-1/L1 and 6 (35.3%) pts had received anti-angiogenesis therapy before enrollment. The median line of previous treatment was 2 (range 1-4). Loss of INI1 was confirmed in 14 (82.4%) pts. Tumor response was evaluated in 14 pts at data cutoff. 9 (64.3%) of 14 pts remained progression-free at 12 weeks. The primary endpoint was met. Based on investigator assessment, 3 (21.4%) of 14 pts achieved partial response and 8 (57.1%) pts had stable disease as best response. Adverse events (AEs) were generally mild. The most common treatment-related hematological AEs were anaemia, platelet count decreased and hyperuricaemia. Conclusions: SHR-2554 showed promising efficacy and an acceptable safety profile in pts with refractory ES, warranting further investigation. Clinical trial information: ChiCTR2100046099.