Over the last decade, various T cell-based immunotherapeutic approaches, including blocking programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) axis, bispecific/trispecific T-cell engagers, and chimeric antigen receptor (CAR) T cells have revolutionized the field of cancer therapeutics. This evidence concerns the gene PDCD1 and cancer.