The utilization of antibodies that inhibit the cytotoxic T lymphocyte antigen 4 (CTLA-4) (9) and programmed cell death protein 1 (PD-1) (10) in the treatment of cancer patients not only signifies the triumph of immune checkpoint blockade therapy but also signifies the initiation of a novel epoch in the field of cancer immunotherapy (7, 11). The gene discussed is PDCD1; the disease is cancer.