In this multicenter, double-blind phase 3 trial, a total of 551 patients with previously untreated, locally advanced or metastatic ESCC and PD-L1 combined positive score of ≥1 were randomized (2:1) to receive serplulimab (an anti-PD-1 antibody; 3 mg/kg) or placebo (on day 1), plus cisplatin (50 mg/m2) (on day 1) and continuous infusion of 5-fluorouracil (1,200 mg/m2) (on days 1 and 2), once every 2 weeks. Here, PDCD1 is linked to esophageal squamous cell carcinoma.