PDCD1 and non-small cell lung carcinoma: The discovery of cytotoxic T lymphocyte-associated molecule-4 (CTLA-4), programmed death-ligand 1 (PD-1), and programmed cell death receptor-1 ligand (PD-L1) pathways has paved the way for the development of ICI therapy, which has significantly improved the survival in patients with NSCLC without EGFR or ALK alterations.