Till now, all Food and Drug Administration (FDA)–approved cancer immunotherapies included interleukin (IL)-2, interferon (IFN), dendritic cell (DC) vaccine, chimeric antigen receptor–T (CAR-T) cells, anti-programmed cell death protein 1 (PD-1)/PD-L1 mAbs, anti–cytotoxic T lymphocyte antigen-4 (anti-CTLA-4), and so on. Here, PDCD1 is linked to cancer.