Background: The indoleamine 2,3-dioxygenase (IDO) pathway is a key counter-regulatory mechanism that, in cancer, is exploited by tumors to evade antitumor immunity. Indoximod is a small-molecule IDO pathway inhibitor that reverses the immunosuppressive effects of low tryptophan (Trp) and high kynurenine (Kyn) that result from IDO activity. In this study, indoximod was used in combination with a checkpoint inhibitor (CPI) pembrolizumab for the treatment for advanced melanoma.
View Article and Find Full Text PDFImportance: Indoleamine 2,3-dioxygenase 1 (IDO1) causes tumor immune suppression. The IDO1 pathway inhibitor indoximod combined with a taxane in patients with ERBB2-negative metastatic breast cancer was tested in a prospective clinical trial.
Objective: To assess clinical outcomes in patients with ERBB2-negative metastatic breast cancer treated with indoximod plus a taxane.
Indoximod has shaped our understanding of the biology of IDO1 in the control of immune responses, though its mechanism of action has been poorly understood. Previous studies demonstrated that indoximod creates a tryptophan (Trp) sufficiency signal that reactivates mTOR in the context of low Trp concentrations, thus opposing the effects caused by IDO1. Here we extend the understanding of indoximod's mechanism of action by showing that it has pleiotropic effects on immune regulation.
View Article and Find Full Text PDFA series of different prodrugs of indoximod, including estesrs and peptide amides were synthesized with the aim of improving its oral bioavailability in humans. The pharmacokinetics of prodrugs that were stable in buffers, plasma and simulated gastric and intestinal fluids was first assessed in rats after oral dosing in solution or in capsule formulation. Two prodrugs that produced the highest exposure to indoximod in rats were further tested in Cynomolgus monkeys, a species in which indoximod has oral bioavailability of 6-10% and an equivalent dose-dependent exposure profile as humans.
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