CTLA4 and neoplasm: Immune checkpoint inhibitors (ICIs) can restore the immune response against cancer by blocking inhibitory molecules, such as cytotoxic T lymphocyte-associated protein 4 (CTLA-4), programmed death-1 (PD-1) and its ligand (PD-L1), expressed on immune and/or tumor cells, the so-called immune checkpoints (1–3).