CTLA4 and melanoma: Ipilimumab is a fully humanized immunoglobulin (Ig)G1 monoclonal antibody that blocks cytotoxic T-lymphocyte antigen (CTLA-4) and is one of the promising drugs that enhance the anti-tumor immune response for patients with advanced melanoma with or without BRAF gene mutation in combination with nivolumab (1, 4, 9).