IDO-IN-4 is primarily used in research and development within the pharmaceutical and biomedical fields. It serves as a potent inhibitor of indoleamine 2,3-dioxygenase (IDO), an enzyme involved in immune regulation and tumor immune escape. By blocking IDO activity, it helps in studying and potentially enhancing immune responses against cancer cells. This compound is valuable in preclinical studies for evaluating its efficacy in immunotherapy, particularly in cancer treatment strategies. Additionally, it aids in understanding the role of IDO in immune tolerance and its impact on various diseases, including autoimmune disorders and infections. Its application is crucial for advancing therapeutic approaches that target immune modulation.