Discovery of Icotinib-1,2,3-Triazole Derivatives as IDO1 Inhibitors

Abstract

Tumor immunotherapy is considered to be a highlight in cancer treatment in recent years. Indoleamine 2,3-dioxygenase 1 (IDO1) is closely related to the over expression of many cancers, and is therefore a promising target for tumor immunotherapy. To search for novel IDO1-targeting therapeutic agents, 22 icotinib-linked 1,2,3-triazole derivatives were prepared and evaluated for their inhibitory activity against IDO1. The structures of the prepared compounds were confirmed with¹H NMR, ¹³C NMR and HR MS. IDO1 inhibitory activity assay results indicated that 10 of those compounds showed remarkable inhibitory activity against IDO1, among which compound a17 was the most potent with IC₅₀value of 0.37 μM. The binding model between the prepared compounds and IDO1 was studied with molecular modeling study. The current study suggested that icotinib-1,2,3-triazole derivatives could be used as potential inhibitors that preferentially bind to the ferrous form of IDO1 through the formation of coordinate bond with the haem iron.

Keywords: 1,2,3-triazole; icotinib; immunotherapy; indoleamine 2,3-dioxygenase 1; inhibitor.

Graphical Abstract

Figure 1

Chemical structures of sixIDO1 inhibitors.

Figure 2

The reaction routes to1,2,3-triazole-linkedicotinibderivatives.

Figure 3

The binding mode of compounds in complex with IDO1. Theprotein is represented by a green cartoon, while compound a17 (pink, A) and compound a18 (yellow, B) are represented as sticks. The hydrogen bonds are colored in red dash.

Figure 4

The binding mode of compounds in complex with IDO1. Theprotein is represented by a green cartoon, while compound a3 (pink, A) and compound a12 (yellow, B) are represented as sticks. The hydrogen bonds are colored in red dash.