Ipilimumab, an anti‐CTLA‐4 (cytotoxic T lymphocyte‐associated antigen‐4) human monoclonal antibody (IgG1) that blocks the T‐cell co‐inhibitory signal 5, 6 demonstrated significant survival benefit in metastatic melanoma patients regardless of BRAF mutation status, whereas tremelimumab, another anti‐CTLA‐4 IgG2 monoclonal antibody, failed to show such benefit 7. This evidence concerns the gene CTLA4 and metastatic melanoma.