PDCD1 and small cell lung carcinoma: Recently, the efficacy of immune checkpoint inhibitors (ICIs) such as Programmed Cell Death-1 (PD-1)/Programmed Death-Ligand 1 (PD-L1) inhibitors (pembrolizumab (Pem), durvalumab (Dur), or atezolizumab (Atz)) plus platinum–etoposide (EP) for previously untreated ES-SCLC has been reported [6,7,8].