TDO/IDO Inhibitor(Curadev Pharma Pvt Ltd.)

Human tryptophan dioxygenase (TDO) and indoleamine 2,3-dioxygenase (IDO) are two important targets in cancer immunotherapy. Extensive research has led to a large number of potent IDO inhibitors; in addition, 52 structures of IDO in complex with inhibitors with a wide array of chemical scaffolds have been documented. In contrast, progress in the development of TDO inhibitors has been limited. Only four structures of TDO in complex with competitive inhibitors that compete with the substrate L-tryptophan for binding to the active site have been reported to date. Here we systematically evaluated the structures of TDO in complex with competitive inhibitors with three types of pharmacophores, imidazo-isoindole, indole-tetrazole, and indole-benzotriazole. The comparative assessment of the protein-inhibitor interactions sheds new light into the structure-based design of enzyme-selective inhibitors.

Indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO) are attractive drug targets for cancer immunotherapy. After disappointing results of the epacadostat as a selective IDO inhibitor in phase III clinical trials, there is much interest in the development of the TDO selective inhibitors. In the current study, several data analysis methods and machine learning approaches including logistic regression, Random Forest, XGBoost and Support Vector Machines were used to model a data set of compounds retrieved from ChEMBL. Models based on the Morgan fingerprints revealed notable fragments for the selective inhibition of the IDO, TDO or both. Multiple fragment docking was performed to find the best set of bound fragments and their orientation in the space for efficient linking. Linking the fragments and optimization of the final molecules were accomplished by means of an artificial intelligence generative framework. Finally, selectivity of the optimized molecules was assessed and the top 4 lead molecules were filtered through PAINS, Brenk and NIH filters. Results indicated that phenyloxalamide, fluoroquinoline, and 3-bromo-4-fluroaniline confer selectivity towards the IDO inhibition. Correspondingly, 1-benzyl-1H-naphtho[2,3-d][1,2,3]triazole-4,9-dione was found to be an integral fragment for the selective inhibition of the TDO by constituting a coordination bond with the Fe atom of heme. In addition, furo[2,3-c]pyridine-2,3-diamine was found as a common fragment for inhibition of the both targets and can be used in the design of the dual target inhibitors of the IDO and TDO. The new fragments introduced here can be a useful building blocks for incorporation into the selective TDO or dual IDO/TDO inhibitors.