CTLA4 and neoplasm: To elude the immune system, tumor cells grow a locally immunosuppressed microenvironment, that down-regulate T cells activation by creating inhibitory pathways: these latter exploit cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), and programmed death-ligand 1 (PD-L1) and its receptor [programmed death-1 (PD-1)/PD-L1].