Efficacy of niraparib by timing of surgery and residual disease: a post-hoc analysis of patients in the PRIMA/ENGOT-OV26/GOG-3012 study

Objectives: Niraparib is a poly(ADP-ribose) polymerase (PARP) inhibitor approved as maintenance treatment for patients (pts) with newly diagnosed advanced or recurrent ovarian cancer following a response to platinum-based chemotherapy (CT) doublet. The PRIMA/ENGOT-OV26/GOG-3012 (NCT02655016) study showed that niraparib following first-line treatment improved progression-free survival (PFS) in the overall intention-to-treat (ITT) population (hazard ratio [HR] 0.62; 95% CI 0.50-0.76). Methods: This double-blind, placebo (PBO)-controlled, phase 3 trial evaluated niraparib in pts with newly diagnosed, advanced, high-grade serous or endometrioid ovarian, primary peritoneal, or fallopian tube cancer with a complete or partial response to first-line CT. Pts were considered to be at a high risk for disease progression based on their clinical characteristics. This post-hoc analysis presents the efficacy of niraparib, measured by PFS, based on time of surgery and residual disease status, and was not powered to determine differences among the subgroups. Results: Data cutoff was May 2019. In total, 733 pts were randomized in the PRIMA study. Efficacy outcomes by surgical timing, either primary debulking surgery (PDS) or interval debulking surgery (IDS), and postoperative residual disease status, either no visible residual disease (NVRD) or visible residual disease (VRD), are shown in Table. Pts who underwent PDS or IDS had similar efficacy with niraparib maintenance treatment versus PBO in the ITT population (PFS HRs were 0.67 and 0.57, respectively). Niraparib treatment reduced risk of progression by 42% in pts who received PDS and had VRD, 35% in those with IDS and NVRD, and 59% in those with IDS and VRD. Efficacy was not evaluable for pts with PDS and NVRD due to low sample size. Download : Download high-res image (142KB) Download : Download full-size image Conclusions: In this post-hoc analysis, the impact of residual disease after PDS or IDS on the efficacy of niraparib was comparable across subgroups. Pts with IDS and VRD had the highest reduction in the risk of progression