@article {Suzuki607, author = {Kokichi Suzuki and Yuko Muto and Kenichi Fushihara and Ken-ichi Kanemoto and Hiroyuki Iida and Eriko Sato and Chika Kikuchi and Tetsuya Matsushima and Emiko Kato and Masahiro Nomoto and Shin Yoshioka and Hidemi Ishii}, title = {Enhancement of Fibrinolysis by EF6265 [(S)-7-Amino-2-[[[(R)-2-methyl-1-(3-phenylpropanoylamino)propyl]hydroxyphosphinoyl] methyl]heptanoic Acid], a Specific Inhibitor of Plasma Carboxypeptidase B}, volume = {309}, number = {2}, pages = {607--615}, year = {2004}, doi = {10.1124/jpet.103.062729}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {Plasma procarboxypeptidase B, also known as thrombin-activatable fibrinolysis inhibitor (TAFI), is converted by thrombin into the active enzyme, carboxypeptidase B (CPB)/activated TAFI. Plasma CPB down-regulates fibrinolysis by removing carboxy-terminal lysines, the ligands for plasminogen and tissue-type plasminogen activator (tPA), from partially degraded fibrin. To target thrombosis in a new way, we have identified and optimized a phosphinic acid-containing inhibitor of CPB, EF6265 [(S)-7-amino-2-[[[(R)-2-methyl-1-(3-phenylpropanoylamino) propyl]hydroxyphosphinoyl]methyl]heptanoic acid] and determined both the pharmacological profile and pathophysiological role of CPB in rat thrombolysis. EF6265 specifically inhibited plasma CPB activity with an IC50 (50\% inhibitory concentration) of 8.3 nM and enhanced tPA-mediated clot lysis in a concentration-dependent manner. EF6265 decreased detectable thrombi (percentage of glomerular fibrin deposition; control, 98 {\textpm} 1.1; EF6265, 0.1 mg/kg, 27 {\textpm} 9.1) that had been generated by tissue factor in a rat microthrombosis model with concomitant increases in plasma D-dimer concentration (control, \<0.5 μg/ml; EF6265, 0.1 mg/kg, 15 {\textpm} 3.5 μg/ml). EF6265 reduced plasma α2-antiplasmin activity to a lesser extent than tPA. In an arteriovenous shunt model, EF6265 (1 mg/kg) enhanced exogenous tPA-mediated thrombolysis under the same conditions that neither EF6265 nor tPA (600 kIU/kg) alone reduced thrombi. EF6265 (1 and 30 mg/kg) did not affect the bleeding time in rats. Moreover, it did not prolong the bleeding time evoked by tPA (600 kIU/kg). These results confirm that circulating procarboxypeptidase B functions as a fibrinolysis inhibitor{\textquoteright}s zymogen and validates the use of CPB inhibitors as both an enhancer of physiological fibrinolysis in microcirculation and as a novel adjunctive agent to tPA for thromboembolic diseases while maintaining a small effect on primary hemostasis. The American Society for Pharmacology and Experimental Therapeutics}, issn = {0022-3565}, URL = {https://jpet.aspetjournals.org/content/309/2/607}, eprint = {https://jpet.aspetjournals.org/content/309/2/607.full.pdf}, journal = {Journal of Pharmacology and Experimental Therapeutics} }