Blocking the immune checkpoints including programmed cell death 1 (PD‐1)/programmed cell death 1 ligand (PD‐L1) and cytotoxic T‐lymphocyte antigen‐4 (CTLA‐4) significantly prolongs the overall survival of 20–30% patients of most subtypes of cancers [3, 4]. Here, PDCD1 is linked to cancer.