CD274 and neoplasm: The immunohistochemical PD-L1 expression test using Dako’s 22C3 assay for the primary esophageal tumor showed a tumor proportion score (TPS, which is calculated as the number of PD-L1 positive tumor cells divided by the total number of all tumor cells multiplied by 100) of 0 with a combined positive score (CPS, which is calculated as the number of PD-L1 positive cells, including tumor cells, lymphocytes, and macrophages divided by the total number of viable tumor cells multiplied by 100) of <1 (Figure 1B).