Abstract
Inhibition of hypoxia inducible factor prolyl hydroxylase (PHD) represents a promising strategy for the discovery of a next generation treatment for renal anemia. We identified several 5,6-fused ring systems as novel scaffolds of the PHD inhibitor on the basis of pharmacophore analysis. In particular, triazolopyridine derivatives showed potent PHD2 inhibitory activities. Examination of the predominance of the triazolopyridines in potency by electrostatic calculations suggested favorable π-π stacking interactions with Tyr310. Lead optimization to improve the efficacy of erythropoietin release in cells and in vivo by improving cell permeability led to the discovery of JTZ-951 (compound 14), with a 5-phenethyl substituent on the triazolopyridine group, which increased hemoglobin levels with daily oral dosing in rats. Compound 14 was rapidly absorbed after oral administration and disappeared shortly thereafter, which could be advantageous in terms of safety. Compound 14 was selected as a clinical candidate.