The successful phase 3 niraparib ENGOT-OV16/NOVA trial included a substantial number of patients with platinum resistant ovarian cancer (OC).

Abstract

5560 Background: Niraparib is a highly selective poly (ADP-ribose) polymerase (PARP) 1/2 inhibitor (PARPi); in preclinical studies, it concentrates in the tumor relative to plasma to deliver durable, near complete PARP inhibition and persistent antitumor effects.Niraparib demonstrated significantly longer progression free survival (PFS) vs placebo in patients (pts) with recurrent OC who were randomized following a complete response (CR) or partial response (PR) to platinum based chemotherapy in the controlled, double-blind phase 3 ENGOT-OV16/NOVA trial. To more fully characterize the NOVA trial population, we assessed platinum resistance status, defined as a duration of response to platinum < 6 months to the most recent (ultimate) platinum regimen. Analysis was limited to pts in the placebo arm, as inclusion of pts receiving active treatment (niraparib) would have confounded the ability to determine duration of response to platinum alone. Methods: Pts with recurrent OC, no prior PARPi use, ≥2 prior courses of platinum based chemotherapy, and CR or PR to the most recent platinum based chemotherapy were eligible. Pts were assigned to one of two cohorts based on g BRCA testing (g BRCAmut or non-g BRCAmut) and randomized 2:1 within each cohort to niraparib 300 mg or placebo qd until progressive disease (PD). Randomization occurred up to 8 weeks following the last dose of the most recent platinum based chemotherapy. PFS was measured from time of randomization to death or earliest PD as assessed by independent review committee. Estimated probability of pts having disease progression in each cohort and pooled across cohorts 6 months after the last dose of their most recent platinum therapy was calculated using the Kaplan-Meier methodology. Results: 181 pts were randomized to placebo (65 g BRCAmut and 116 non-g BRCAmut). Platinum resistance rate estimates for the g BRCAmut, non-g BRCAmut, and pooled cohorts were 42%, 53%, and 49%, respectively. Conclusions: Approximately half of the pts in the NOVA study, where niraparib treatment met its primary endpoint of prolonging PFS following a response to platinum, had developed platinum resistance to their last line of chemotherapy. Clinical trial information: NCT01847274.