IDO-IN-3 is primarily used in research settings as a potent inhibitor of indoleamine 2,3-dioxygenase (IDO), an enzyme involved in immune response modulation. By blocking IDO activity, it helps in studying the enzyme's role in cancer immunotherapy, as IDO is known to promote immune tolerance in tumor microenvironments. This compound is valuable in preclinical studies aimed at understanding and enhancing the efficacy of immune checkpoint therapies. Additionally, it is utilized in exploring autoimmune diseases and inflammatory conditions where IDO activity plays a significant role. Its application contributes to the development of novel therapeutic strategies targeting immune regulation pathways.