Effect of First-Line Serplulimab vs Placebo Added to Chemotherapy on Survival in Patients With Extensive-Stage Small Cell Lung Cancer

Programmed cell death ligand 1 inhibitors combined with chemotherapy has changed the approach to first-line treatment in patients with extensive-stage small cell lung cancer (SCLC). It remained unknown whether adding a programmed cell death 1 (PD-1) inhibitor to chemotherapy provided similar or better benefits in patients with extensive-stage SCLC, which would add evidence on the efficacy of checkpoint inhibitors in the treatment of extensive-stage SCLC.

To evaluate the efficacy and adverse event profile of the PD-1 inhibitor serplulimab plus chemotherapy compared with placebo plus chemotherapy as first-line treatment in patients with extensive-stage SCLC. Design, Setting, and Participants: This international, double-blind, phase 3 randomized clinical trial (ASTRUM-005) enrolled patients at 114 hospital sites in 6 countries between September 12, 2019, and April 27, 2021. Of 894 patients who were screened, 585 with extensive-stage SCLC who had not previously received systemic therapy were randomized. Patients were followed up through October 22, 2021. Interventions: Patients were randomized 2:1 to receive either 4.5 mg/kg of serplulimab (n = 389) or placebo (n = 196) intravenously every 3 weeks. All patients received intravenous carboplatin and etoposide every 3 weeks for up to 12 weeks. Main Outcomes and Measures: The primary outcome was overall survival (prespecified significance threshold at the interim analysis, 2-sided P