CTLA4 and melanoma: Immunotherapy based on immune-checkpoint blockers (ICBs), especially combination of therapies targeting programmed cell death inhibitor 1 (PD-1) and its ligand (programmed cell death ligand 1, PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), has made a significant impact on the outcome of malignant melanoma [1–3].