IDO-IN-1 is a potent and selective inhibitor of indoleamine 2,3-dioxygenase 1 (IDO1), an enzyme involved in immune regulation. Its primary application lies in cancer immunotherapy, where it helps reverse the immunosuppressive tumor microenvironment. By blocking IDO1 activity, IDO-IN-1 prevents the breakdown of tryptophan, thereby restoring T-cell function and enhancing anti-tumor immune responses. It is widely used in research settings to study immune checkpoint pathways and to develop combination therapies with other immunotherapeutic agents such as PD-1/PD-L1 inhibitors. Additionally, IDO-IN-1 has been explored in inflammatory and autoimmune disease models due to the role of IDO1 in modulating immune tolerance.