Used in pharmaceutical research as a potent and selective inhibitor of indoleamine 2,3-dioxygenase 1 (IDO1), an enzyme involved in immune regulation. It modulates the immune response by blocking the metabolism of tryptophan along the kynurenine pathway, thereby preventing immunosuppression in the tumor microenvironment. Investigated for potential use in cancer immunotherapy, particularly in combination with other immune checkpoint inhibitors. Also employed as a biochemical tool to study IDO1 enzyme activity and pathway dynamics in cellular and animal models.