Cytotoxic-T-lymphocyte-associated antigen-4 (CTLA-4) polymorphisms rs4553808, rs11571317, and rs231775 have been associated with response to therapy with ipilimumab for metastatic melanoma, and the CTLA-4 rs4553808 has also been correlated with higher incidence of endocrine side effects [65,66]. Here, CTLA4 is linked to metastatic melanoma.