Discovery of the First Potent IDO1/IDO2 Dual Inhibitors: A Promising Strategy for Cancer Immunotherapy

Indoleamine 2,3-dioxygenase-1 (IDO1) plays an important role in tumor immune escape. However, unsatisfactory clinical efficacies of selective IDO1 inhibitors have impeded their further development, suggesting that they do not exert sufficient antitumor effects by selectively inhibiting IDO1. IDO2, an isoenzyme of IDO1, is overexpressed in some human tumors, and emerging evidence suggests that concomitant inhibition of IDO1/2 may have synergistic...