Comparison of survival outcomes and safety between early and late initiation of niraparib maintenance in newly diagnosed advanced epithelial ovarian cancer

Objective This multicenter retrospective cohort study aimed to compare survival outcomes and adverse events between early and late initiation of niraparib maintenance therapy in patients with newly diagnosed advanced ovarian cancer. Methods We included patients with stage III–IV ovarian cancer who showed a complete or partial response to frontline platinum-based chemotherapy and received niraparib maintenance therapy between October 2019 and December 2022. The primary endpoint was the HR for progression-free survival based on the median initiation interval, which was defined as the duration between the completion of chemotherapy and commencement of maintenance therapy. The secondary endpoint was the comparison of progression-free survival at another time point that determined the interval that maximized the difference between the survival curves of the two groups using the Contal and O’Quigley method. Results This analysis included 146 patients who received niraparib maintenance therapy. The median age was 58 years (IQR 50–63.3). The median initiation interval was 8.4 (IQR 5.7–8.9) weeks. After adjusting for prognostic factors for progression-free survival identified through multivariable analysis, early initiation (≤8 weeks) of niraparib was associated with significantly better progression-free survival (HR=0.57; 95% CI 0.33 to 0.99; p=0.047). Furthermore, the initiation interval that maximized the difference in progression-free survival was 6 weeks. Multivariable analysis revealed that early initiation (≤6 weeks) of niraparib significantly increased progression-free survival (HR=0.37; 95% CI 0.18 to 0.76; p=0.007). The rate of treatment discontinuation due to treatment-emergent adverse events was higher (12.5% versus. 2.8%; p=0.036) in patients receiving niraparib within 6 weeks than those treated later, with no significant effect in those initiating treatment within 8 weeks. Conclusion Early initiation of niraparib maintenance therapy within 8 weeks of chemotherapy completion improved progression-free survival, with further benefits observed with treatment within 6 weeks in patients with newly diagnosed advanced ovarian cancer.