Extended Data Table 4.

Summary of adverse events in the safety set

Data are n (%). The safety set included all patients who received at least one dose of study treatment. Adverse events were recorded from the first dose of study treatment until 90 days after the last dose or the start of new antitumor treatment, whichever occurred first. CF = cisplatin and 5-fluorouracil. *Inclusive of 15 patients who were randomized to receive placebo plus chemotherapy, but received serplulimab plus chemotherapy due to an error in drug distribution. †Immune-related adverse events were defined as adverse events that were associated with drug exposure and demonstrated immune-mediated mechanisms with no other unequivocal etiology.