IDO1 INHIBITORS FOR CANCER IMMUNOTHERAPY

Preclinical data suggests that indoleamine 2,3-dioxygenase (IDO) can induce tumor-mediated immune suppression through increased tryptophan catabolism that leads to decreased activation of cytotoxic T cells in response to an antigenic challenge. Blockade of IDO using small molecules can reverse this effect in vitro and in animal models. Clinical trials are evaluating the safety and efficacy of three compounds - indoximod, epacadostat and GDC-0919 - across a wide range of indications and combinations. The drug class appears to be safe and combines well with a variety of different treatment modalities. Based on available data supporting an important role for IDO in cancer immunotherapy, continued clinical investigation using novel IDO inhibitors is warranted.