Current therapeutic strategies for the treatment of metastatic melanoma focus on two major approaches with proven clinical efficacy: (i) direct targeting of activated oncogenes in melanoma cells such as BRAF [53] or (ii) indirect targeting of melanoma cells by T-cell stimulation with anti-CTLA4- or anti-PD-1-antibodies [54, 55]. This evidence concerns the gene CTLA4 and metastatic melanoma.