nivolumab + IDO1 inhibitor

Combination of **nivolumab** (a monoclonal antibody immune checkpoint inhibitor targeting PD-1) and an **IDO1 inhibitor** (commonly BMS-986205, a small molecule orally administered inhibitor of indoleamine 2,3-dioxygenase 1). The rationale for the combination is that IDO1 orchestrates immune suppression and contributes to resistance against immune checkpoint inhibitors. The dual inhibition aims to overcome tumor immune escape by blocking both the suppressive effects of PD-1/PD-L1 signaling and tryptophan metabolism via IDO1. This combination has been investigated in several phase I/II clinical trials across tumor types including hepatocellular carcinoma, endometrial cancer, melanoma, and glioblastoma, with mechanistic synergy observed preclinically and some clinical evidence of enhanced antitumor activity and tolerable safety profiles[1][3][4][5].