Used in cancer immunotherapy as a potent and selective indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor. It enhances anti-tumor immune responses by blocking IDO1-mediated tryptophan metabolism in tumor cells and antigen-presenting cells, which otherwise suppresses T-cell activity and promotes immune tolerance. BMS-986205 is investigated in clinical trials, often in combination with immune checkpoint inhibitors like nivolumab, to improve outcomes in various solid tumors including melanoma, non-small cell lung cancer, and bladder cancer. Its ability to reverse the immunosuppressive tumor microenvironment makes it a promising candidate for combination immunotherapies.