ICIs target various co‐stimulatory signalling molecules on T lymphocytes and antigen‐presenting cells, such as cytotoxic T‐lymphocyte antigen 4 (CTLA‐4), programmed cell death protein 1 (PD‐1), and its ligand (PD‐L1), thereby breaking the immune tolerance of T cells against cancer cells.24 This evidence concerns the gene PDCD1 and cancer.