CD274 and small cell lung carcinoma: KEYNOTE-028 (n = 19) and KEYNOTE-158 (n = 64) showed that Pembrolizumab exhibited durable antitumor activity in a subset of patients with recurrent or metastatic SCLC, regardless of PD-L1 combined positive score (CPS) (26, 27), revealing that PD-L1 expression cannot predict the efficacy of ICIs in the ES-SCLC, whether assessed by TPS or CPS.