Reinvigoration of exhausted T cells by blocking immune checkpoint markers, such as cytotoxic T cells antigen-4 (CTLA4), programmed cell death 1 (PD-1) and PD-1 ligand (PDL-1), have recently received Food and Drug Administration approval for the treatment of melanoma, renal cell carcinoma, and non-small cells lung cancer [65]. The gene discussed is PDCD1; the disease is melanoma.