From a biomolecular point of view, ICIs act by blocking inhibitory pathways in T lymphocytes (T cells) mediated by CTLA-4 (cytotoxic T-lymphocyte antigen 4), PD-1 (programmed cell death protein-1), and PD-L1 (programmed death ligand 1), with the aim of avoiding immune tolerance and increasing the T-cell ability to identify and respond to tumour cells [3]. The gene discussed is PDCD1; the disease is neoplasm.