37MO - Niraparib maintenance therapy in patients with newly diagnosed advanced ovarian cancer: a post hoc analysis on efficacy by surgical timing and residual disease status in the phase III PRIME trial

Background

The PRIME (NCT03709316) study was a randomized, double-blind, placebo-controlled, phase 3 trial. Eligible patients were randomised (2:1) to receive niraparib or placebo. Niraparib maintenance therapy with an individualized starting dose (ISD) improved PFS vs placebo (HR 0.45; 95% CI, 0.34–0.60) in Chinese patients with newly diagnosed, advanced ovarian cancer and CR or PR to 1L platinum-based chemotherapy. This post-hoc analysis aims to evaluate niraparib efficacy by the timing of debulking surgery and postoperative residual disease status.

Methods

This analysis reports PFS and HRs based on surgical timing (primary debulking surgery [PDS] and interval debulking surgery [IDS]) and residual disease status [optimal(R0/R1) vs suboptimal(R2)]. Median PFS (assessed by BICR) and HRs were obtained using the Kaplan-Meier method and stratified Cox proportional hazards models, respectively.

Results

The DCO date was 30 Sep. 2021. In total, 255 patients were randomized and treated to niraparib (134 PDS, 121 IDS) and 129 to placebo (70 PDS, 59 IDS). The PFS median follow-up was 27.5 months. The efficacy results are shown in the table. Niraparib significantly prolonged PFS compared with placebo irrespective of surgical timing. For PFS, HR 0.63 (95% CI 0.42–0.94, median PFS was not reached in niraparib arm vs. 12.0 months in placebo arm) in patients who underwent PDS; HR = 0.32 (95% CI 0.21-0.48, median PFS in niraparib and placebo arm was 22.3 vs. 5.6 months) in patients undergoing IDS. In niraparib-treated patients, those who underwent PDS and IDS experienced similar rates of grade ≥3 adverse events (TEAEs) (50.7% vs 58.7%) and treatment discontinuation due to AEs (6.7% vs 6.6%).

Figure 1

Conclusions

This subgroup analysis demonstrated that niraparib improved PFS regardless of surgical timing compared with placebo in patients with newly diagnosed advanced ovarian cancer.

Clinical trial identification

NCT03709316.

Legal entity responsible for the study

Zai Lab.

Funding

This study was funded by Zai Lab (Shanghai) Co., Ltd and partially supported by the National Major Scientific and Technological Special Project for Significant New Drugs Development in 2020, China [grant number 2020ZX09101-014].

Disclosure

X. Zhen: Financial Interests, Personal, Stocks/Shares: Zai Lab (Shanghai) Co., Ltd; Financial Interests, Personal, Full or part-time Employment: Zai Lab (Shanghai) Co., Ltd. W. Hang: Financial Interests, Personal, Full or part-time Employment: Zai Lab (Shanghai) Co., Ltd; Financial Interests, Personal, Stocks/Shares: Zai Lab (Shanghai) Co., Ltd. J. Hou: Financial Interests, Personal, Full or part-time Employment: Zai Lab (Shanghai) Co., Ltd; Financial Interests, Personal, Stocks/Shares: Zai Lab (Shanghai) Co., Ltd. All other authors have declared no conflicts of interest.