IDO Believe in Immunotherapy

Abstract IDO1 is central to immune downregulation. A recent phase I/II study tested the IDO1 inhibitor linrodostat with nivolumab +/- ipilimumab in patients with advanced solid tumors. While efficacy was not augmented, correlative analyses identified TDO2 as a resistance mechanism; dual targeting may be necessary to realize improved response to PD-1 inhibition.