IDO1 and cancer: In particular, they devised a library of fused imidazole derivatives as IDO1 inhibitors.77 Although scant data are available on this class of compounds in the literature, NLG919 (GDC0919, 6, structure undisclosed) was first reported at the 104th Annual Meeting of the American Association for Cancer Research as the most interesting compound of the series.78 The compound proved a potent orally bioavailable IDO1 inhibitor (Ki = 7 nM; EC50 = 75 nM), showing favorable pharmacokinetic and toxicity profiles.