Targeting the indoleamine 2,3-dioxygenase pathway in cancer

Table 1 Reported IDO inhibitors

Agent	Mechanism	First author, year
D-1MT	Tryptophan mimetic; D isoform of MT; Transcriptional suppressor of IDO	Metz 2012 [32]
L-1MT	Tryptophan mimetic; L isoform of MT; selective IDO1 inhibitor	Opitz 201 [39]
MTH-Trp	Tryptophan mimetic; transcriptional suppressor of IDO	Okamoto 2007 [92]
β-carbolines	Tryptophan mimetic; IDO and TDO inhibitor	Eguchi 1984 [93]
Naphthoquinone-based	Pharmacophore of natural product annulin B; indole mimetic; IDO inhibitor	Kumar 2008 [94]
S-allyl-brassinin	Phytoalexin; indole mimetic	Gaspari 2006 [95]
S-benzyl-brassinin	Phytoalexin; indole mimetic	Gaspari 2006 [95]
5-Bromo-brassinin	Phytoalexin; indole mimetic	Banerjee 2008 [96]
Phenylimidazole-based	Computationally designed synthetic IDO inhibitor	Kumar 2008 [94]
4-phenylimidazole	Heme ligand in IDO enzyme	Sono 1989 [97]
Exiguamine A	Non-tryptophan analogue	Harry 2006 [98]
NSC401366	Non-indolic IDO inhibitor	Vottero 2006 [99]

IDO Indoleamine-2,3-dioxygenase 1, 1MT 1-methyl-DL-tryptophan, MTH-Trp methylthiohydantoin-dl-tryptophan, TDO tryptophan-2,3-dioxygenase