BMS-986205 is primarily used in the field of oncology as an investigational drug. It functions as an IDO1 (indoleamine 2,3-dioxygenase 1) inhibitor, which plays a role in modulating the immune system's response to cancer. By blocking IDO1, it helps to prevent the suppression of T-cells, thereby enhancing the immune system's ability to attack tumor cells. This makes it a potential candidate for combination therapies with other immunotherapies, such as checkpoint inhibitors, to improve treatment outcomes in various cancers, including melanoma and lung cancer. Its application is currently under clinical trials to evaluate its efficacy and safety in cancer treatment regimens.