Objective: The primary objective of this study was to evaluate the safety of niraparib 300 mg/day in Japanese patients with platinum-sensitive, relapsed ovarian cancer in a maintenance setting.
Methods: Phase 2, multicenter, open-label, single-arm study enrolled Japanese patients with platinum-sensitive, relapsed ovarian cancer who had received ≥2 platinum-based regimens. The primary endpoint (incidence of grade 3 or 4 thrombocytopenia-related events within 30 days after initial niraparib administration) was justified by the incidences of a global pivotal phase 3 study and its post-hoc safety analysis on thrombocytopenia, the major hematological adverse event of niraparib. The overall safety analysis examined other treatment-emergent adverse events (TEAEs).
Results: Enrolled patients (n=19) had a median (min, max) body weight of 53.9 (40.8-79.1) kg; all but one patient weighed <77 kg. Most (94.7%) patients initially received niraparib 300 mg/day but this decreased in subsequent cycles (mean±standard deviation dose intensity, 191.6±65.7 mg/day). In total, 6/19 (31.6%) patients experienced grade 3 or 4 thrombocytopenia-related events within 30 days of initial niraparib administration. Other common TEAEs included nausea, and decreased platelet or neutrophil counts. No progression-free or overall survival events occurred; only 1 of 4 response-evaluable patients had a post-baseline tumor assessment (stable disease).
Conclusion: The incidence of grade 3 or 4 thrombocytopenia-related events in Japanese ovarian cancer patients was similar to that in the corresponding non-Japanese study. Overall, the safety profile was acceptable and consistent with the known safety profile and previous experience with niraparib.
Trial registration: ClinicalTrials.gov Identifier: NCT03759587.
Keywords: Japanese; Maintenance Therapy; Niraparib; Ovarian Cancer; Phase 2.
Copyright © 2021. Asian Society of Gynecologic Oncology, Korean Society of Gynecologic Oncology, and Japan Society of Gynecologic Oncology.