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. 2015 Nov 12;58(21):8513-28. doi: 10.1021/acs.jmedchem.5b00963. Epub 2015 Oct 28.


Myeloperoxidase (MPO) is a heme peroxidase that catalyzes the production of hypochlorous acid. Clinical evidence suggests a causal role for MPO in various autoimmune and inflammatory disorders including vasculitis and cardiovascular and Parkinson's diseases, implying that MPO inhibitors may represent a therapeutic treatment option. Herein, we present the design, synthesis, and preclinical evaluation of N1-substituted-6-arylthiouracils as potent and selective inhibitors of MPO. Inhibition proceeded in a time-dependent manner by a covalent, irreversible mechanism, which was dependent upon MPO catalysis, consistent with mechanism-based inactivation. N1-Substituted-6-arylthiouracils exhibited low partition ratios and high selectivity for MPO over thyroid peroxidase and cytochrome P450 isoforms. N1-Substituted-6-arylthiouracils also demonstrated inhibition of MPO activity in lipopolysaccharide-stimulated human whole blood. Robust inhibition of plasma MPO activity was demonstrated with the lead compound 2-(6-(5-chloro-2-methoxyphenyl)-4-oxo-2-thioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide (PF-06282999, 8) upon oral administration to lipopolysaccharide-treated cynomolgus monkeys. On the basis of its pharmacological and pharmacokinetic profile, PF-06282999 has been advanced to first-in-human pharmacokinetic and safety studies.

MeSH terms

  • Acetamides / chemistry
  • Acetamides / pharmacokinetics
  • Acetamides / pharmacology*
  • Animals
  • Cardiovascular Diseases / drug therapy*
  • Cardiovascular Diseases / enzymology*
  • Drug Discovery
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacokinetics
  • Enzyme Inhibitors / pharmacology*
  • Humans
  • Peroxidase / antagonists & inhibitors*
  • Peroxidase / metabolism
  • Pyrimidinones / chemistry
  • Pyrimidinones / pharmacokinetics
  • Pyrimidinones / pharmacology*
  • Rats, Wistar


  • Acetamides
  • Enzyme Inhibitors
  • Pyrimidinones
  • Peroxidase
  • 2-(6-(5-chloro-2-methoxyphenyl)-4-oxo-2-thioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamide