PF-06282999

Kinase experiment:

Test compound is incubated with human whole blood stimulated with bacterial LPS for 4 h, followed by capture of MPO on immobilized anti-MPO antibody coated plates. The captured MPO is washed and residual MPO activity is determined using Amplex Red and H2O2.

Animal experiment:

In order to ascertain whether the advances noted in the in vitro and ex vivo assays for candidate thiouracil derivatives translated to effective irreversible inhibition of MPO in vivo, PF-06282999 is also advanced to an in vivo pharmacology study in cynomolgus monkeys using iv endotoxin (LPS) challenge, a classic model of inflammatory leukocyte activation with corresponding MPO activation demonstrated in various species including human. In this randomized crossover study, cynomolgus monkeys are orally administered either vehicle or PF-06282999 (5, 20, and 80 mg/kg) 1 h after iv administration of LPS. Blood is sampled throughout the study and heparinized plasma prepared for MPO activity measurements as well as determination of 8 plasma concentrations. Total MPO is captured using anti-MPO antibody coated plates, and following exchange of plasma for drug-free assay media, the residual activity of the captured MPO is measured using the peroxidation of Amplex Red. A mixed effect sigmoid model is applied to study the relationship between plasma exposure of PF-06282999 and the MPO capture activity at 2 h after dose and 3 h after LPS administration, which corresponds to the peak of MPO activity.

References:

[1]. Dong JQ, et al. Pharmacokinetics and Disposition of the Thiouracil Derivative PF-06282999, an Orally Bioavailable, Irreversible Inactivator of Myeloperoxidase Enzyme, Across Animals and Humans. Drug Metab Dispos. 2016 Feb;44(2):209-19.
[2]. Ruggeri RB, et al. Discovery of 2-(6-(5-Chloro-2-methoxyphenyl)-4-oxo-2-thioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide (PF-06282999): A Highly Selective Mechanism-Based Myeloperoxidase Inhibitor for the Treatment of Cardiovascular Diseases. J Med Chem. 20