PDCD1 and cancer: These range from adoptive cell transfer, including genetically modified autologous cells such as T-cells with chimeric antigen receptors (CAR), anti-cancer vaccines, and immune checkpoint inhibitors [4], e.g., antibodies that block programmed cell death protein 1 (PD-1), programmed cell death ligand 1 (PD-L1), or cytotoxic T lymphocyte antigen 4 (CTLA4).