Cancer immunotherapy with immune checkpoint inhibitors (ICIs), including monoclonal antibodies (mAbs) against cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and PD-1/PD-L1, rescues dysfunctional cytotoxic effector CD8+ T cells, leading to tumour regression [3, 4]. This evidence concerns the gene PDCD1 and neoplasm.