Final survival analysis of NSGO-AVANOVA2/ENGOT-OV24: Combination of niraparib and bevacizumab versus niraparib alone as treatment of recurrent platinum-sensitive ovarian cancer—A randomized controlled chemotherapy-free study.

Abstract

6012 Background: We previously reported significantly improved progression-free survival (PFS) with the chemotherapy-free regimen of niraparib and bevacizumab compared to niraparib alone, in women with platinum-sensitive relapsed ovarian cancer (PSROC), regardless of homologous recombination deficiency (HRD) status (MyChoice HRD), duration of chemotherapy-free interval (CFI) and number of previous lines of therapy (Mirza MR et al, Lancet Oncol 2019). We now present the updated PFS, overall survival (OS) and other efficacy and safety endpoints. Methods: In this randomized, open-label, phase 2 study, women with measurable/evaluable, high-grade serous or endometrioid PSROC were randomized to niraparib 300mg once daily or the combination of niraparib 300mg once daily and bevacizumab 15mg/kg IV every 3 weeks until disease progression (1:1 randomization). The primary endpoint was PFS. Stratification was according to HRD status and CFI (6-12months (mo) vs. > 12mo). First-line maintenance bevacizumab was permitted. Results: Of 97 enrolled patients, 48 were randomized to niraparib monotherapy and 49 to the chemotherapy-free combination. The combined treatment significantly improved PFS compared to niraparib alone: updated median PFS 12.5 mo vs. 5.5 mo; hazard ratio (HR) adjusted for stratification factors 0.34; 95% confidence interval (CI) [0.21 to 0.55]; P < 0.0001. Preplanned exploratory subgroup analyses: patients with HRD-positive tumors (n = 54) HR 0.41 (CI, 0.23-0.76); HRD-negative disease (n = 43) HR, 0.40 (CI, 0.20-0.79); Time to First Subsequent Therapy (TFST) (n=97) HR, 0.4 (CI, 0.25-0.64); PFS2 (n=97) HR 0.55 (CI, 0.35-0.88); Time to Second Subsequent Therapy (TSST) (n=97) HR, 0.56 (CI, 0.35-0.90); OS (49 events only) HR, 0.77 (CI, 0.42-1.41). There was no difference in treatment-emergent grade 3-4 adverse events except for the rate of hypertension (22.9% vs. 0%) and neutropenia (8.3% vs. 2.0%). Patient-reported outcomes measured using EORTC QLQ-C30 and OV28 were similar for both treatment arms. Conclusions: Updated PFS consistently demonstrates that the niraparib-bevacizumab combination had clinically and statistically meaningful activity in PSROC. This phase 2 study was not powered to detect differences in OS or any other efficacy endpoints however TFST, PFS2 & TSST are significantly improved while there is a trend towards OS improvement with niraparib-bevacizumab combination. Clinical trial information: NCT02354131.