Tumor PD-L1 expression was assessed by immunohistochemistry at a central laboratory using a prototype assay (QualTek molecular laboratories, Goleta, CA, United States of America) (28) and the 22C3 antibody (Merck and co, Kenilworth, NJ, United States of America). PD-L1 expression was determined by combined positive score (CPS), defined as the number of PD-l1–positive cells (tumor cells, lymphocytes, and macrophages) divided by the total number of tumor cells, multiplied by 100. The specimen is considered to have positive PD-L1 expression when CPS ≥1. Here, CD274 is linked to neoplasm.