These specifically target the Programmed cell death-1 (PD-1) receptor expressed on T-cells and its receptor ligand, Programmed-death ligand-1 (PD-L1) expressed by target cells in the tumor microenvironment, as well as the Cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) found on the cell surface of activated T-cells. The gene discussed is PDCD1; the disease is neoplasm.