Faculty of 1000 evaluation for Molecular and cellular mechanisms of HIF prolyl hydroxylase inhibitors in clinical trials.

Inhibition of the human 2-oxoglutarate (2OG) dependent hypoxia inducible factor (HIF) prolyl hydroxylases (human PHD1 – 3) causes upregulation of HIF, thus promoting erythropoiesis and is therefore of therapeutic interest. We describe cellular, biophysical, and biochemical studies comparing four PHD inhibitors currently in clinical trials for anaemia treatment, that describe their mechanisms of action, potency against isolated enzymes and in cells, and selectivities versus representatives of other human 2OG oxygenase subfamilies. The ‘ clinical ’ PHD inhibitors are potent inhibitors of PHD catalyzed hydroxylation of the HIF- a oxygen dependent degradation domains (ODDs), and selective against most, but not all, representatives of other human 2OG dependent dioxygenase subfamilies. Crystallographic and NMR studies provide insights into the di ff erent active site binding modes of the inhibitors. Cell-based results reveal the inhibitors have similar e ff ects on the upregulation of HIF target genes, but di ff er in the kinetics of their e ff ects and in extent of inhibition of hydroxylation of the N- and C-terminal ODDs; the latter di ff erences correlate with the biophysical observations.