title: Discovery of potent & selective inhibitors of activated thrombin-activatable fibrinolysis inhibitor for the treatment of thrombosis.
abstract: Thrombin-activatable fibrinolysis inhibitor (TAFI) has emerged as a key link between the coagulation and fibrinolysis cascades and represents a promising new target for the treatment of thrombosis. A novel series of imidazolepropionic acids has been designed that exhibit high potency against activated TAFI (TAFIa) and excellent selectivity over plasma carboxypeptidase N (CPN). Structure activity relationships suggest that the imidazole moiety plays a key role in binding to the catalytic zinc of TAFIa, and this has been supported by crystallographic studies using porcine pancreatic carboxypeptidase B as a surrogate for TAFIa. The SAR program led to the identification of 21 (TAFIa Ki = 10 nM, selectivity TAFIa/CPN > 1000) as a candidate for clinical development. Compound 21 exhibited antithrombotic efficacy in a rabbit model of venous thrombosis, yet had no effect on surgical bleeding in the rabbit. In addition, 21 exhibited an excellent preclinical and clinical pharmacokinetic profile, characterized by paracellular absorption, low clearance, and a low volume of distribution, fully consistent with its physicochemical properties of low molecular weight (MW = 239) and high hydrophilicity (log D = -2.8). These data indicate 21 (UK-396,082) has potential as a novel TAFIa inhibitor for the treatment of thrombosis and other fibrin-dependent diseases in humans.
authors.affiliation: Pfizer Global Research and Development, Sandwich Laboratories, Ramsgate Road, Kent, U.K. mark.bunnage@pfizer.com
authors.forename: Mark E
authors.initials: ME
authors.lastname: Bunnage
authors.forename: Julian
authors.initials: J
authors.lastname: Blagg
authors.forename: John
authors.initials: J
authors.lastname: Steele
authors.forename: Dafydd R
authors.initials: DR
authors.lastname: Owen
authors.forename: Charlotte
authors.initials: C
authors.lastname: Allerton
authors.forename: Andrew B
authors.initials: AB
authors.lastname: McElroy
authors.forename: Duncan
authors.initials: D
authors.lastname: Miller
authors.forename: Tracy
authors.initials: T
authors.lastname: Ringer
authors.forename: Ken
authors.initials: K
authors.lastname: Butcher
authors.forename: Kevin
authors.initials: K
authors.lastname: Beaumont
authors.forename: Karen
authors.initials: K
authors.lastname: Evans
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Gray
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Holland
authors.forename: Neil
authors.initials: N
authors.lastname: Feeder
authors.forename: Robert S
authors.initials: RS
authors.lastname: Moore
authors.forename: David G
authors.initials: DG
authors.lastname: Brown
mesh_terms: D000596:Amino Acids / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D001682:Biological Availability; D016063:Blood Loss, Surgical / Q000517:prevention & control; D043424:Carboxypeptidase B / Q000737:chemistry; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004285:Dogs; D005342:Fibrinolysis / Q000187:drug effects*; D005343:Fibrinolytic Agents / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000494:pharmacology; D006207:Half-Life; D006801:Humans; D007093:Imidazoles / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000494:pharmacology; D008297:Male; D008958:Models, Molecular; D015394:Molecular Structure; D010179:Pancreas / Q000201:enzymology; D011817:Rabbits; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013552:Swine; D013917:Thrombin / Q000378:metabolism*; D054556:Venous Thromboembolism / Q000188:drug therapy
chemical_list: C526817:5-amino-2-((1-n-propyl-1H-imidazol-4-yl)methyl)pentanoic acid; D000596:Amino Acids; D005343:Fibrinolytic Agents; D007093:Imidazoles; D043424:Carboxypeptidase B; D013917:Thrombin