Randomization and masking
CPS, DISEASE
Eligible patients were randomly assigned (2:1) using an integrated web response system to receive serplulimab plus chemotherapy or placebo plus chemotherapy. Randomization was stratified by PD-L1 expression level (CPS ≥ 10 versus CPS < 10), age (≥65 years versus <65 years) and disease status (locally advanced versus distantly metastatic). Patients, investigators and the sponsor’s study team were masked to group assignment.