Activity of regorafenib (RE) in leiomyosarcomas (LMS) and other types of soft-tissue sarcomas (OTS): Results of a double-blind, randomized placebo (PL) controlled phase II trial.

10504 Background: RE is a multikinase inhibitor that has demonstrated activity in gastrointestinal stromal tumors. We investigated its activity and safety in anthracycline pretreated metastatic soft tissue sarcomas (STS). Methods: REGOSARC (NCT01900743) consisted of four independent cohorts of patients (pts) with LMS, OTS, synovial, and adipocytic sarcomas who were randomized (1:1) to receive either RE (160 mg/d, 21/28 d) or PL, with optional cross-over. Key-eligibility criteria were age ≥ 18, measurable progressing STS not amenable to curative-intent surgery, ≤ 3 previous lines of treatment for metastatic STS. The primary endpoint was progression-free survival (PFS) with blinded central radiological review. Statistical assumptions for LMS and OTS cohorts were PFS = 1.6 months (mo) with PL, PFS = 4.6 mo with RE, 1-sided α = 0.1 and β = 0.05. Results: From July 2013 to July 2014, 57 LMS and 53 OTS pts were enrolled (55 with PL, 55 with RE). The two most common OTS types were Undifferentiated Pleomorphic Sa...