CTLA4 and melanoma: Thus, antibodies that block the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), the programmed cell death receptor 1 (PD-1), or the programmed cell death ligand 1 (PD-L1) have been successful in enhancing the host’s attack on various tumor types, including melanoma, lung, bladder, and many others [14].