Tumor tissues contain many immunotherapy-related targets, including antibodies against cytotoxic T lymphocyte-associated antigen 4 (CTLA4) that induce antitumor immunity, PD-1 that restricts T-cell effector function within tissues, and PD-L1 that blocks antitumor immune responses in the tumor microenvironment. Here, PDCD1 is linked to neoplasm.