Aims
The PRIME study (NCT03709316) evaluated the efficacy and safety of niraparib using an individualized starting dose as maintenance treatment following complete or partial response (CR/PR) to first-line (1L) platinum-based chemotherapy (CT) in Chinese patients with advanced ovarian cancer (OC).
Methods
In this double-blind, placebo-controlled, phase 3 study, patients with newly diagnosed, advanced (stage III–IV) OC were randomized 2:1 to niraparib or placebo after CR/PR to 1L CT. The study aimed to recruit 381 patients. Patients in the niraparib arm received 200 mg once daily, except patients with baseline body weight ≥77 kg and platelet count ≥150,000/μL who received 300 mg once daily. Patients were stratified by germline BRCA (gBRCA) status, tumor homologous recombination deficiency/proficiency (HRd/HRp) status, neoadjuvant chemotherapy, and best response to 1L CT. Primary endpoint was progression-free survival (PFS); secondary endpoint included overall survival (OS). All efficacy outcomes were analyzed based on the intention-to-treat population.
Results
Of 384 randomized patients (niraparib, n=255; placebo, n=129), 125 (32.6%) were gBRCA-mutated and 257 (66.9%) were HRd. Median follow-up was 27.5 months. Median PFS was significantly longer in patients receiving niraparib compared with placebo (24.8 vs 8.3 months; HR 0.45; 95% CI 0.34–0.60; P<0.001). Treatment benefit was demonstrated in HRd-subgroup (HR 0.48; 95% CI 0.34–0.68; P<0.001) and HRp-subgroup (HR 0.41; 95% CI 0.25–0.65; P<0.001) subgroups. OS data was immature (HR 0.63; 95% CI 0.38–1.03; P=0.061). The most common grade ≥3 adverse events in the niraparib arm were anemia (18.0%), neutrophil count decreased (17.3%) and platelet count decreased (14.1%).
Conclusions
This phase 3 study is the first to confirm the efficacy and safety of niraparib in Chinese patients with advanced OC. Niraparib resulted in a clinically meaningful and significant PFS improvement over placebo, regardless of biomarker status. Niraparib was well tolerated, and no new safety signals were identified.