Efficacy and Safety of Niraparib as Maintenance Treatment in Patients With Extensive-Stage SCLC After First-Line Chemotherapy: A Randomized, Double-Blind, Phase 3 Study.

Introduction: ZL-2306-005 is a randomized, double-blind, multicenter phase 3 study evaluating the efficacy and safety of niraparib, a poly(adenosine diphosphate-ribose) polymerase inhibitor, as first-line maintenance therapy in Chinese patients with platinum-responsive, extensive-stage SCLC (ES-SCLC).
Methods: Patients with complete response (CR) or partial response (PR) to standardized, platinum-based first-line chemotherapy were randomized 2:1 to receive niraparib or placebo (300 mg [baseline body weight ≥ 77 kg, platelet count ≥ 150,000/μL] or 200 mg) once daily until progression or unacceptable toxicity. Primary end points were progression-free survival (PFS) (blinded independent central review) and overall survival (sample size planned: 591 patients). Secondary end points included investigator-evaluated PFS and safety.
Results: ZL-2306-005 was terminated early owing to ES-SCLC treatment landscape changes (data cutoff: March 20, 2020). During July 2018-February 2020, a total of 185 of 272 patients screened were randomized (niraparib: n = 125 [CR = 1, PR = 124]; placebo: n = 60 [CR = 1, PR = 59]). Median (95% confidence interval [CI]) PFS (blinded independent central review) was 1.54 months (1.41-2.69, niraparib) and 1.36 months (1.31-1.48, placebo); hazard ratio (HR) = 0.66 (95% CI: 0.46-0.95, p = 0.0242). Median overall survival was 9.92 months (9.33-13.54, niraparib) and 11.43 months (9.53-not estimable, placebo); HR = 1.03 (95% CI: 0.62-1.73, p = 0.9052). Median investigator-evaluated PFS was 1.48 months (1.41-2.56, niraparib) and 1.41 months (1.31-2.00, placebo); HR = 0.88 (95% CI: 0.61-1.26; p = 0.4653). Grade greater than or equal to 3 adverse events occurred in 34.4% (niraparib) and 25.0% (placebo) of patients.
Conclusions: ZL-2306-005 did not reach primary end points. Nevertheless, niraparib as maintenance therapy modestly improved PFS in patients with platinum-responsive ES-SCLC, with acceptable tolerability profile and no new safety signal.
(Copyright © 2021 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.)