A Series of 2‐((1‐Phenyl‐1H‐imidazol‐5‐yl)methyl)‐1H‐indoles as Indoleamine 2,3‐Dioxygenase 1 (IDO1) Inhibitors
Yong Zheng, Paul M. Stafford, Kurt R. Stover, Darapaneni Chandra Mohan, Mayuri Gupta, Eric C. Keske, Paolo Schiavini, Laura Villar, Fan Wu, Alexander Kreft, Kiersten Thomas, Elana Raaphorst, Jagadeesh Prasad Pasangulapati, Siva R. Alla, Simmi Sharma, Ramana R. Mittapalli, Irina K. Sagamanova, Shea L. Johnson, Mark A. Reed, Donald F. Weaver
Abstract
Abstract Indoleamine 2,3‐dioxygenase 1 (IDO1) is a promising therapeutic target in cancer immunotherapy and neurological disease. Thus, searching for highly active inhibitors for use in human cancers is now a focus of widespread research and development efforts. In this study, we report the structure‐based design of 2‐(5‐imidazolyl)indole derivatives, a series of novel IDO1 inhibitors which have been designed and synthesized based on our previous study using N 1‐substituted 5‐indoleimidazoles. Among these, we have identified one with a strong IDO1 inhibitory activity (IC 50 =0.16 μM, EC 50 =0.3 μM). Structural‐activity relationship (SAR) and computational docking simulations suggest that a hydroxyl group favorably interacts with a proximal Ser167 residue in Pocket A, improving IDO1 inhibitory potency. The brain penetrance of potent compounds was estimated by calculation of the Blood Brain Barrier (BBB) Score and Brain Exposure Efficiency (BEE) Score. Many compounds had favorable scores and the two most promising compounds were advanced to a pharmacokinetic study which demonstrated that both compounds were brain penetrant. We have thus discovered a flexible scaffold for brain penetrant IDO1 inhibitors, exemplified by several potent, brain penetrant, agents. With this promising scaffold, we provide herein a basis for further development of brain penetrant IDO1 inhibitors.