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

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

Background: SOLO2 (ENGOT ov-21; NCT01874353) showed that maintenance therapy with the PARP inhibitor olaparib in pts with platinum-sensitive relapsed ovarian cancer (PSROC) and a BRCA mutation (BRCAm) led to a statistically significant improvement in median progression-free survival (PFS) of 13.6 months vs placebo (hazard ratio [HR] 0.30). Time to second progression or death significantly improved (Pujade-Lauraine et al Lancet Oncol 2017) and a quality-adjusted PFS benefit was seen (Friedlander et al Lancet Oncol 2018) with maintenance olaparib vs placebo. We report the preplanned final OS analysis for SOLO2.

Methods: Pts with PSROC and a BRCAm who had received ≥2 lines of treatment and were in response to their most recent platinum-based chemotherapy received maintenance olaparib (300 mg bid tablets) or placebo. Pts were stratified by response to previous chemotherapy (complete vs partial) and length of platinum-free interval (>6–12 months vs >12 months). OS was a secondary endpoint. The only preplanned OS sensitivity analysis was an OS analysis in the Myriad germline BRCAm subset (Myriad BRAC Analysis test).

Results: At final data cut-off (Feb 3, 2020), median follow-up was 65 months in both treatment arms. A long-term treatment benefit was seen with olaparib vs placebo with an OS HR of 0.74 (95% confidence interval [CI] 0.54–1.00) in the full analysis set (FAS; unadjusted for crossover; 38.4% of placebo pts crossed over to a PARP inhibitor) (Table). At 5 years: by Kaplan-Meier estimates, 28.3% of pts in the olaparib arm vs 12.8% of pts in the placebo arm were alive and had still not received subsequent treatment; 42.1% of olaparib pts vs 33.2% of placebo pts were alive. The long-term tolerability profile of olaparib was generally consistent with that reported previously.

Conclusions: In the final analysis of SOLO2, maintenance olaparib provided an unprecedented improvement of 12.9 months in median OS vs placebo. This is the first study with olaparib tablets, and the first since Study 19 (NCT00753545), to provide long-term follow-up and final OS data in pts with PSROC and a BRCAm. Clinical trial information: NCT01874353.


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