CTLA4 and melanoma: Immune checkpoint inhibitors (ICIs) targeting cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) or programmed cell death 1 receptor (PD-1)/programmedcell death 1 ligand 1 (PD-L1) pathways are influencing new cancer treatment model sand producing unprecedented clinical effects in a wide diversity of cancers, such as melanoma, renal cell carcinoma, lung cancer, urothelial cancer, or head and neck cancer1–6.