There are currently 12 actively recruiting phase III/IV clinical trials on stage IV melanoma patients exploring several new treatment avenues, including but not limited to the combination of granulocyte-macrophage colony-stimulating factor (GM-CSF) with immunotherapy [NCT02339571], CpGA DNA Toll-like receptor agonist with pembrolizumab [NCT04695977], an immunomodulatory vaccine against indoleamine 2,3-dioxygenase (IDO) with nivolumab [NCT05155254], and HDAC inhibitor with nivolumab [NCT04674683]. This evidence concerns the gene IDO2 and melanoma.