A Double-Blind Placebo-Controlled Randomized Phase Ii Trial Assessing The Activity And Safety Of Regorafenib (Reg) In Patients (Pts) With Nonadipocytic Soft Tissue Sarcoma (Sts) Previously Treated With Pazopanib (Paz).

11021 Background: After we demonstrated the activity of REG in pts with advanced non-adipocytic STS (MirTLO 2016), we conducted a dedicated study in pts previously treated with PAZ+chemo. Methods: We report here the 5th cohort of a double-blind randomized phase 2 trial (NCT01900743). Pts were treated with regorafenib (160mg/d, 21/28d) or placebo (PB). Pts receiving placebo were offered optional cross-over in case of centrally confirmed disease progression. The primary endpoint was centrally-reviewed RECIST-based progression-free survival (PFS), evaluated on the intent-to-treat dataset. A total of 24 events was required to ensure a 90%-power for HR = 0.33 (median PFS, 3·6 vs 1·2 months), with a 1-sided α = 0·1. Overall survival (OS) was a secondary endpoint. Results: From 12/2015 to 10/2017, 37 pts were randomized (18 REG vs 19 PB) and included in the final analysis. The median age was 60 (36-76). There were 28 women (76%). All pts had a performance status 0 or 1. Histological subtypes included 24 leiomyosarcoma (11 vs 13, in REG and PB, respectively), 1 synovial sarcoma (REG), 12 other sarcoma (7 vs 5). All pts had previously been treated with PAZ +chemo (including doxorubicin: 19 vs 17; ifosfamide: 11 vs 3; trabectedin: 11 vs 9; and dacarbazine: 7 vs 6), with 2-6 prior lines. The median relative dose intensity of REG was 0·86, range 0·41-1. Out of 19 pts assigned to placebo, 13 switched to REG after progression. There was no reported objective response. We observed a significant benefit of REG compared to PB in terms of PFS (HR = 0·38; 95%CI, 0·19-0·76; p = 0·007; median PFS = 2·1 vs 1·1 months, respectively), and OS despite the cross-over (HR = 0·41; 95%CI, 0·17-0·98; p = 0·04; median OS = 18·6 vs 8·2 months). Before cross-over, the most common clinically significant grade 3 or higher adverse events were diarrhea (4 vs 0), dyspnea (3 vs 1), arterial hypertension (2 vs 0), hand-foot skin reaction (2 vs 0). Conclusions: The present study demonstrates that regorafenib has a clinically meaningful anti-tumor activity in pts with non-adipocytic soft tissue sarcoma pretreated by both chemotherapy and pazopanib, improving PFS and OS. Clinical trial information: NCT01900743.