ENGOT-OV16/NOVA trial of niraparib in recurrent ovarian cancer: Survival and long-term safety

Objective: To evaluate secondary efficacy endpoints and safety for the ENGOT-OV16/NOVA (NCT01847274) trial of niraparib maintenance therapy after extended follow-up and vital-status-data retrieval. Previously reported analyses (data cutoff, October 1, 2020) indicated benefit of niraparib maintenance therapy beyond first progression, but overall survival (OS) analyses were limited by missing data. Methods: Patients were randomized 2:1 to niraparib (300 mg once daily) or placebo. A vital status check was extended to retrieve last-known-alive status for patients with missing survival data. Prespecified secondary efficacy outcomes (OS, chemotherapy-free interval [CFI], time to first subsequent therapy [TFST], PFS2, time to second subsequent therapy [TSST]) and safety are reported based on the extended data cutoff (March 31, 2021). Results: Survival status was available for 97.6% (540/553) of randomized patients (germline BRCA [gBRCA]-mutated, 203; non-gBRCA–mutated, 350). Median OS with niraparib and placebo was 40.9 and 38.1 months, respectively, in the gBRCA-mutated cohort (hazard ratio [HR], 0.85; 95% confidence interval [CI], 0.61–1.20) and 31.0 and 34.8 months, respectively, in the non-gBRCA–mutated cohort (HR, 1.06; 95% CI, 0.81–1.37). Medians for CFI, TFST, PFS2, and TSST numerically favored niraparib in both cohorts. No new safety signals were detected. Conclusions: OS did not significantly differ between treatment arms. Prespecified secondary efficacy endpoints numerically favored niraparib. Long-term safety remained consistent with the established niraparib safety profile. Taken together with the significant improvements in PFS observed in the primary analysis, these data support a favorable overall benefit–risk profile for niraparib in the recurrent OC maintenance setting.