CTLA4 and neoplasm: They act by targeting immune checkpoints expressed by tumor infiltrating lymphocytes (TILs)—programmed-death 1 (PD-1) or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4)—or expressed by cancer and tumor infiltrating immune cells—programmed-death ligand 1 (PD-L1) [18].