A Phase II Multicenter Trial of Trabectedin in Combination with Olaparib in Patients with Advanced Unresectable or Metastatic Sarcoma.

PURPOSE: Soft-tissue sarcomas are rare malignancies with poor prognosis and limited systemic treatment options. We conducted a phase II study to assess the efficacy and safety of trabectedin and olaparib in patients with advanced disease. PATIENTS AND METHODS: Patients with soft-tissue sarcoma who received ≥1 prior therapy were recruited into two cohorts. Cohort 1 included leiomyosarcoma and liposarcoma; cohort 2 included other histologies. All patients received trabectedin (1.1 mg/m2 24-hour infusion every 21 days) and olaparib (150 mg twice daily continuously). The study was conducted using a Simon minimax two-stage design with a primary endpoint of objective response (OR) rate per RECIST 1.1. RESULTS: Twenty-nine (cohort 1, 16; cohort 2, 13) patients enrolled; one patient in cohort 2 was not evaluable. There were no confirmed ORs in cohort 1; the best response was stable disease in 12 (75%) patients and progressive disease in four (25%). Two partial responses were observed in cohort 2 (n = 12). The most common adverse events were fatigue (75%), neutropenia (75%), anemia (68%), and thrombocytopenia (68%). The median progression-free survival and overall survival for all patients were 3.5 (95% confidence interval, 3.3-8.2) and 13.2 months (95% confidence interval, 10.3-20.9), respectively. Next-generation sequencing of 17 tumors revealed multiple abnormalities, most commonly in TP53, RB1, and ATRX. CONCLUSIONS: Trabectedin plus olaparib conferred high rates of toxicity and failed to demonstrate ORs in leiomyosarcoma and liposarcoma. Preliminary evidence of clinical benefit in two patients in cohort 2 suggests potential value of either or both drugs in other sarcomas.