PDCD1 and non-small cell lung carcinoma: With recent advance of immune checkpoint inhibitor treatment that blocks the PD-1 (programmed cell death 1) and PD-L1 (programmed cell death-ligand 1) pathway, pembrolizumab monotherapy has replaced platinum-doublet chemotherapy as first-line treatment in patients with advanced non-small cell lung carcinoma (NSCLC) and a PD-L1 tumor proportion score (TPS) of 50% or more [1].