IDO1 and neoplasm: Additionally, inhibitors of several key metabolic enzymes, such as IDH1(Isocitrate Dehydrogenase 1), IDO1((Indoleamine 2,3-dioxygenase 1), GPX4(Glutathione Peroxidase 4), and NAMPT(Nicotinamide phosphoribosyltransferase), have shown good anti-tumor effects [10–13].