(Rac)-Indoximod (1-Methyl-DL-tryptophan) is a potent inhibitor of indoleamine 2,3-dioxygenase (IDO). Combined treatment with IFN-γ and (Rac)-Indoximod significantly suppresses the activity of α-SMA-expressing human cardiac myofibroblasts (hCMs) and promotes apoptosis by up-regulating the genes IRF-1, Fas, and FasL. Moreover, this co-treatment effectively improves cardiac fibrosis[1].