PDCD1 and cancer: In recent years, cancer immunotherapy has achieved some significant clinical successes, including cancer vaccines obtaining FDA approval, and immune checkpoint blockade (ICB) [192], adoptive cell transfer (ACT) [193], monoclonal antibody (mAbs) therapy [194], and chimeric antigen receptor (CAR) T cell therapy with programmed cell death 1 (PD-1) [195] or its ligand (PD-L1) [196] as immune checkpoint inhibitors have shown promise.