In patients with platinum-sensitive relapsed ovarian cancer harboring BRCA1/2 mutation, final overall survival (OS) results from the phase-3 SOLO2/ENGOT-ov21 trial showed significant benefit for patients receiving maintenance treatment with olaparib over placebo.
Prof. Andrés Poveda (Hospital Quironsalud, Spain) presented the results, after approximately 5 years of follow-up . The trial enrolled patients with a BRCA mutation with relapsed high-grade serous ovarian cancer or endometrioid cancer. Patients had received at least 2 prior lines of platinum-based chemotherapy and were in complete or partial response.
Participants were randomized to receive 300 mg olaparib twice daily (n=196) or placebo (n=99), and treatment continued until disease progression occurred, with a median follow-up of 65.7 months in the olaparib arm and 64.5 months in the placebo arm. The primary endpoint was met, maintenance olaparib led to a median progression-free survival benefit of 13.6 months over placebo (19.1 vs 5.5 months; HR 0.30; 95% CI 0.22-0.41; P <0.0001).
The median OS, unadjusted for crossover, was 51.7 months with olaparib versus 38.8 months with placebo (HR 0.74; 95% CI 0.54-1.00; P=0.0537). At 5 years, 42.1% of patients in the olaparib group were still alive compared with 33.2% in the placebo group; however, 39% of patients in the placebo arm crossed over to olaparib. Patients with germline BRCA mutation had median OS of 52.4 months in the olaparib arm (n=190) versus 37.4 months in the placebo arm (n=96) (HR 0.71; 95% CI 0.52-0.97; P=0.0306).
Long-term tolerability of olaparib revealed no new safety events; the most common adverse events were nausea, fatigue/asthenia, and anemia. Dose interruptions were reported for 50% of patients receiving olaparib and 19% of patients receiving a placebo. Treatment discontinuations were reported in 17% of patients in the olaparib arm and in 3% of patients in the placebo group.
Prof. Poveda concluded: “SOLO2 was the first randomized phase 3 trial to provide OS data on PARP maintenance therapy. These results demonstrate that olaparib maintenance monotherapy not only delays disease progression but also improves OS in women with platinum-sensitive ovarian cancer and a BRCA mutation.”
1. Poveda A, et al Final overall survival (OS) results from SOLO2/ENGOT-ov21: A phase III trial assessing maintenance olaparib in patients (pts) with platinum-sensitive, relapsed ovarian cancer, and a BRCA mutation. ASCO Virtual Meeting, 29-31 May 2020, Abstract 6002.