Introduction/Background BACKGROUND: While an increasing number of patients with BRCA-mutated ovarian cancer receive first-line maintenance PARP inhibitors, there is still a group of patients who are PARPi naïve for various reasons, and who relapse. A subgroup analysis of the SOLO2 trial of maintenance olaparib provides information about the outcome of patients receiving maintenance olaparib after a response to platinum-based therapy for first recurrence.

Methodology In SOLO2/ENGOT-Ov21 patients with high grade ovarian cancer and a BRCA-mutation were randomised 2:1 to receive olaparib or placebo after a response to platinum-based therapy. Out of the 295 patients enrolled in the trial, 172 had one prior line of chemotherapy (110 olaparib; 62 placebo) prior to recurrence. Treatment with olaparib or placebo continued until progression, toxicity, or lack of further clinical benefit. An exploratory analysis of progression-free survival (PFS) and overall survival (OS) was performed as well as the long-term toxicity.

Results In the 172 second-line patients, a complete response to chemotherapy was seen in 52%, and 70% had a platinum-free interval of more than 12 months before randomisation. The median PFS was 24.2 (16.4–33.2) versus 5.7 (95%CI 5.3–8.2) months in the olaparib and placebo arms respectively (HR 0.46, 95%CI 0.32–0.66). With 58% data maturity, OS favoured olaparib (median 56.3 months, 95%CI 43.9–67.4) over placebo (37.4 months, 95%CI 27.1–60.3) (HR 0.79, 95%CI 0.53–1.19).

Conclusion For patients with a BRCA mutation who did not have the opportunity to receive a PARPi in first-line, this exploratory analysis of SOLO2 in patients with first recurrence showed that maintenance olaparib following a response to chemotherapy leads to a clinically meaningful survival benefit. These results support the recommended use of olaparib in this patient subgroup.

Disclosures Sponsored by AstraZeneca. Led by GINECO Group