Combinational immunotherapy using antibodies to CTLA-4, PD-1/PD-L1, with small molecule inhibitors of indolamine deoxygenase (IDO), have also been shown to lead to improved tumor control and increased IL-2 production by tumor infiltrating lymphocytes (TILs) in an implantable melanoma setting [8,9]. This evidence concerns the gene CTLA4 and melanoma.