CTLA4 and melanoma: Immune checkpoint inhibitor (ICI)‐based therapies (especially those targeting anti‐cytotoxic T‐lymphocyte‐associated antigen‐4 (anti‐ctla‐4) and anti‐programmed death‐1 (anti‐pd‐1) antibodies) have dramatically improved overall survival in melanoma in recent years,22 but unfortunately, there are still no validated biomarkers to indicate the therapeutic prognosis of ICL.