Niraparib as maintenance therapy in Japan: a retrospective observational study using a Japanese claims database

Objective: Epithelial ovarian cancer (EOC) is the leading cause of female mortality in gynecologic malignancies, with a rising incidence in Japan. This study aimed to validate the treatment patterns and safety of niraparib as maintenance therapy for EOC following initial chemotherapy in clinical practice in Japan.

Methods: Leveraging claims data between April 2008 and December 2022, this descriptive study comprised EOC-diagnosed patients receiving initial platinum-based chemotherapy, debulking surgery, and niraparib as maintenance therapy. Patient characteristics, prescription status, transfusion details, and laboratory data were assessed and reported as summary statistics and frequencies.

Results: Among 291 patients, the median age was 64.0 years and 94.5% received a 200-mg daily dose of niraparib. At week 12, 78.7% (229/291) continued niraparib treatment, 21.3% (62/291) discontinued, and 52.2% (152/291) required treatment interruptions. Of the 62 patients who discontinued treatment, 27 patients initiated subsequent EOC treatment within 12 weeks following niraparib discontinuation. Blood transfusions were needed in 10.3% (30/291), and of 55 patients with available laboratory data, 61.8% (34/55) had decreased platelet count <100,000/µL, 25.5% (14/55) had decreased hemoglobin level <8 g/dL, and 22.7% (5/22) had decreased neutrophil count <1,000/µL, meeting the criteria for treatment interruption. Among those with thrombocytopenia, 88.2% (30/34) were able to either resume or continue treatment.

Conclusion: Niraparib demonstrated favorable tolerability in Japanese patients with advanced EOC, with effective management of thrombocytopenia through dose adjustments and supportive care, supporting its viability as post-chemotherapy maintenance therapy.