CD274 and esophageal squamous cell carcinoma: Pembrolizumab is approved in Japan for the treatment of patients with radically unresectable advanced or recurrent ESCC of the esophagus whose tumors express PD-L1 (combined positive score [CPS] ≥ 10) with disease progression after ≥ 1 line of chemotherapy based on data from the phase 3 KEYNOTE-181 study [5–7].