Due to severe and in part life-threatening side effects of immune checkpoint inhibitors affecting up to 50% of melanoma patients treated with anti-CTLA-4 immunotherapy [14], and even more when subjected to a combined anti-CTLA-4 and anti-PD-1 therapy [15], there is an urgent quest for new strategies in the battle against metastatic melanoma. This evidence concerns the gene CTLA4 and metastatic melanoma.