PDCD1 and neoplasm: With recent advance of immune checkpoint inhibitors treatment that block the PD-L1 (programmed cell death 1 ligand 1) and PD-1 (programmed cell death 1) pathway, pembrolizumab monotherapy has replaced chemotherapy as the first-line treatment for patients with PD-L1 tumor proportion score (TPS) of at least 50% [4], and pembrolizumab plus platinum and pemetrexed for those with nonsquamous histology irrespective of PD-L1 expression [5, 6].