The first ICI approved for the treatment of metastatic malignant melanoma was ipilimumab, an anti-CTLA-4 antibody which is associated with a median OS of 11.4 months (95% CI, 10.7 to 12.1 months) and a 3-year survival rate of 22% (95% CI, 20% to 24%) [6]. This evidence concerns the gene CTLA4 and metastatic melanoma.