An observational study to investigate the effectiveness and safety of niraparib maintenance therapy after frontline chemotherapy for Taiwanese patients with advanced ovarian cancer: Interim results.

Abstract

e17546 Background: The phase 3 PRIMA trial demonstrated that first-line maintenance therapy (1LMT) with niraparib significantly prolonged progression-free survival (PFS) in patients (pts) with newly diagnosed advanced ovarian cancer (OC), regardless of homologous recombination deficiency (HRD) or BRCA mutation status. However, the trial population was restricted to non-Asian pts at high risk of recurrence, limiting its generalizability. The real-world evidence on niraparib 1LMT remains limited. This first multicenter study of niraparib 1LMT in Taiwan aims to evaluate its real-world effectiveness and safety as 1LMT following frontline platinum-based chemotherapy (1LCT) in pts with advanced OC. Methods: This multicenter, ambispective, observational study enrolled pts with newly diagnosed FIGO stage III–IV epithelial OC who achieved complete response (CR) or partial response (PR) to 1LCT following either primary or interval debulking surgery, irrespective of residual disease status. Eligible pts initiated niraparib 1LMT on or after January 1, 2022. The primary endpoint was clinical effectiveness, including PFS and related outcomes, with subgroup analyses conducted by BRCA and HRD status. The observation period lasted up to 3.5 years from the first dose of niraparib. Interim analyses were conducted with a data cut-off of June 30, 2025. Results: A total of 46 pts were enrolled across 7 medical centers in Taiwan. Among them, the majority of pts exhibited favorable clinical characteristics, including stage III disease (63.0%), primary debulking surgery (78.3%) and CR (56.5%) to 1LCT. 84.8% of pts were BRCA wild-type, 21.7% were categorized as HRD-negative, while HRD status remained unknown in 45.7% of pts. For the PFS analysis of clinical effectiveness, we further excluded 2 pts who received niraparib for less than 30 days and 3 pts who had no tumor assessment recorded either before or after the start of 1LMT. After a median follow-up of 14.9 months, the median PFS (mPFS) was not reached (NR), and the 12-month PFS rate was 75.6% in the overall population. In subgroup analyses, the mPFS for BRCA wild-type/HRD-positive and HRD-negative pts was NR and 20.8 months, respectively, with corresponding 12-month PFS rates of 81.8% and 74.1%. Conclusions: These interim effectiveness results support niraparib as an effective 1LMT for newly diagnosed advanced OC pts in the Taiwanese population, demonstrating consistent benefit across all genetic subgroups. Ongoing long-term follow-up will further substantiate the durability of niraparib’s benefit in a real-world setting. Summary of mPFS by genetic subgroup. Pt Number, N mPFS, month 12-month PFS rate, % All Pts 41 NR 75.6 BRCA status BRCA m 4 NR 100.0 BRCA wt 35 NR 75.3 BRCA unknown 2 NR 100.0 HRD status HRD+ 14 NR 85.1 BRCA wt/HRD+ 11 NR 81.8 HRD- 9 20.8 74.1 HRD unknown 18 NR 75.2