RESUMO
OBJECTIVES: Despite the individualized starting dose for maintenance therapy in ovarian cancer, the niraparib dose reduction rate remains high. The aim of this study was to evaluate the impact of niraparib dose reduction on progression-free survival in newly diagnosed primary advanced ovarian cancer and recurrent ovarian cancer patients. We also aimed to compare the reduction rates and the safety of niraparib on primary and relapse groups, and identify which factors may predict dose reduction. METHODS: Patients with primary or recurrent ovarian cancer in maintenance who received niraparib between 2019 and 2022 were retrospectively evaluated. Niraparib dosing was based on individualized starting dose of 300 or 200 mg/day. The impact of niraparib dose reductions was focused on patients treated with 200 or 100 mg in both groups. Reduction rates, adverse events and predictive factors of reduction were assessed in each study group. The primary endpoint was progression-free survival in primary and relapse groups; the secondary endpoints were the reduction rates, the safety and tolerability of niraparib in both groups. RESULTS: Of 215 patients identified, 124 (57.7%) primary and 91 (42.3%) recurrent ovarian cancer patients were included. The majority of patients started niraparib at 200 mg/day (92.7% primary and 80.2% relapse group); dose reductions from 300 or 200 mg/day to 200 or 100 mg/day occurred more frequently within cycles 1-3 (67% primary and 45% relapse group, p=0.001). Grade≥3 adverse events were lower in the relapse group (54.8% primary and 35.1% relapse, p=0.001). In both groups, dose modifications over the treatment did not significantly impair median progression-free survival. Univariate and multivariate analysis demonstrated that weight and platinum-doublets were possible risk factors for dose reduction. CONCLUSIONS: Niraparib dose reduction occurs in almost half of patients within cycles 1-3, although it is significantly more common in the first-line setting. Survival outcomes seem not to be impaired by dose reduction.