PDCD1 and cancer: Immunotherapy utilizes monoclonal antibodies to target tumor-produced immune checkpoint receptors, such as Programed cell Death protein-1 (PD-1), Programed cell Death protein Ligand-1 (PD-L1) and Cytotoxic T-Lymphocyte–associated Antigen 4 (CTLA-4) that prevent T cells from recognizing and eliminating cancer cells [112,113].