IL4I1 inhibitor

IL4I1 (Interleukin 4 Induced 1) is an L-amino acid oxidase that functions as a metabolic immune checkpoint within the tumor microenvironment. The enzyme metabolizes aromatic amino acids—specifically phenylalanine, tryptophan, and tyrosine—into their respective α-keto acids. Tryptophan metabolism by IL4I1 produces metabolites that act as ligands for the Aryl Hydrocarbon Receptor (AhR), which promotes immune tolerance and suppresses effector T-cell activity. IL4I1 inhibitors are a class of small-molecule therapeutics designed to block this metabolic pathway, thereby restoring anti-tumor immune responses and potentially overcoming resistance to standard immune checkpoint inhibitors like anti-PD-1 therapy. Research by Oncolines and Symeres has identified novel, selective IL4I1 inhibitors from the SymeGold library that demonstrate potency in cellular assays and are being optimized for further evaluation in oncological models.