Zai Lab Limited will present a poster featuring initiation timing analysis from the Phase 3 PRIME study of ZEJULA® (niraparib) as maintenance therapy at the upcoming 2022 International Gynecologic Cancer Society (ICGS) Annual Meeting. This post-hoc analysis of the PRIME Phase 3 study evaluated adults with newly diagnosed advanced ovarian cancer who responded to first-line platinum-based chemotherapy, and they were randomized to receive niraparib maintenance treatment or placebo within 12 weeks after chemotherapy completion. The results are as follows: For patients who received niraparib treatment less than 9 weeks after chemotherapy completion, the median progression-free survival (PFS) (95% CI) was measured at 29.4 months with niraparib versus 8.3 months with placebo (HR =0.31; 95% CI, 0.20–0.48).

For patients who received niraparib at 9 – 12 weeks after chemotherapy completion, the median PFS was 24.7 months with niraparib versus 10.8 months with placebo (HR=0.60; 95% CI, 0.41–0.89). The initiation timing of niraparib maintenance treatment had no significant impact on its safety profile. This subgroup analysis provides evidence to support the initiation of niraparib maintenance treatment in patients with newly diagnosed advanced ovarian cancer within 12 weeks after chemotherapy completion.

The fully powered Phase 3 PRIME study was evaluated in 384 advanced ovarian cancer patients who were in a complete or partial response to platinum-based chemotherapy and who were randomized 2:1 to receive ZEJULA or placebo as maintenance therapy. The study evaluated the efficacy of ZEJULA as a maintenance treatment, with the primary endpoint of PFS as assessed by blinded independent central review. The starting dose was individualized at 200 mg except for those patients with a baseline body weight = 77kg and a platelet count = 150K/µL, in which case the starting dose was 300 mg.