In the CheckMate 648 (CM648) trial, which was a phase III trial comparing nivolumab (Nivo) plus CF or Nivo plus ipilimumab (Nivo + Ipi) to CF in the 1st-line setting advanced ESCC patients, programmed cell death ligand-1 (PD-L1) expression was evaluated using the tumor proportion score (TPS), defined as the ratio of PD-L1 positive tumor cells divided by the total number of tumor cells multiplied by 100. This evidence concerns the gene CD274 and esophageal squamous cell carcinoma.