CTLA4 and neoplasm: Programmed cell death 1 (PD‐1), programmed death ligand‐1 (PD‐L1) and Cytotoxic T‐lymphocyte‐associated protein‐4 (CTLA‐4) could inhibit the proliferation and differentiation of immunocompetent cells and the recognition of tumour cells by tumour‐infiltrating lymphocytes (TILs).