PDCD1 and neoplasm: Immune checkpoint inhibitors (ICIs), such as programmed cell death protein 1/programmed death-ligand 1 (PD-L1) axis inhibitors, were found to have outstanding efficacy in many types of malignant neoplasms, including NSCLC.3, 4, 5, 6, 7, 8, 9 Particularly, pembrolizumab monotherapy is one of the standard first-line treatment options for patients with advanced NSCLC and PD-L1 tumor proportion score (TPS) more than or equal to 50%.6