Efficacy of olaparib maintenance therapy in patients (pts) with platinum-sensitive relapsed ovarian cancer (PSROC) by lines of prior chemotherapy: Phase III SOLO2 trial (ENGOT Ov-21)

Abstract

Background: In the Phase III SOLO2 trial (NCT01874353), maintenance treatment with the poly(ADP‐ribose) polymerase inhibitor olaparib (Lynparza) was shown to significantly improve progression‐free survival (PFS) vs placebo in pts with PSROC and a BRCA1/2 mutation (BRCAm; hazard ratio [HR] 0.30, 95% CI 0.22‐0.41; P<0.0001; median 19.1 vs 5.5 months; Pujade‐Lauraine et al. SGO 2017). A previous retrospective analysis of data pooled from 6 studies of olaparib in pts with a germline BRCAmsuggested that olaparib activity declined as the number of prior lines of chemotherapy received increased (Matulonis et al. Ann Onc 2016). We report an analysis of PFS in SOLO2, grouped by number of prior lines of platinum‐based chemotherapy (PBC) received by pts, performed to identify the most appropriate use of olaparib in the maintenance setting. Methods: SOLO2 enrolled pts who had received ≥2 prior lines of PBC before being in response to their most recent regimen. Pts were randomized 2:1 to receive olaparib tablets (300 mg bid) or placebo. PFS was investigator assessed with modified RECIST v1.1. For the PFS subgroup analyses, subgroups were predefined; HRs were calculated using a Cox proportional hazards model. Results: Of 295 randomized pts, 195 received olaparib and 99 received placebo. 85 pts in the olaparib arm (43.4%) had received ≥3 prior lines vs 37 pts (37.4%) in the placebo arm. Pts who had received 2 prior lines of PBC were more likely to have had a platinum‐ free interval of >12 months (70.9% vs 48.3% and 40.0% for 3 and≥4 prior lines, respectively in the olaparib arm; 69.4% vs 60.0% and 23.5% placebo) and a complete response at baseline (50.9% vs 36.7% and 48.0% olaparib; 54.8% vs 35.0% and 35.3% placebo) vs pts who had received ≥3 prior lines. Conclusions: In SOLO2, olaparib maintenance monotherapy improved PFS in pts with PSROC irrespective of the number of prior lines of PBC received.