A chemically-modified inactive antithrombin as a potent antagonist of fondaparinux and heparin anticoagulant activity

Abstract

To cite this article: Fazavana J, Bianchini EP, Saller F, Smadja C, Picard V, Taverna M, Borgel D. A chemically-modified inactive antithrombin as a potent antagonist of fondaparinux and heparin anticoagulant activity. J Thromb Haemost 2013; 11: 1128-36.Summary. Background: Heparin and its analogs, mediating their anticoagulant activity through antithrombin (AT) activation, remain largely used for the preventive and curative treatment of thrombosis. The major adverse reaction of these drugs is the bleeding risk associated with overdose. Unfractionnated heparin (UFH) can be efficiently and rapidly neutralized by protamine sulfate, but this reversal partially neutralizes low-molecular-weight heparin (LMWH) and is inefficient in reversing fondaparinux. To secure administration of AT-mediated anticoagulants and counteract bleeding disorders, we previously designed a recombinant inactive AT as an antidote to heparin derivatives. Objectives: To get around the limited production level of recombinant AT, we propose in this study an alternative strategy to produce a chemically modified inactive AT, exhibiting increased heparin affinity, as an antagonist of heparin analogs. Methods: Plasma-derived AT was chemically modified with 2,3 butanedione, a diketone known to specifically react with the arginine side chain. The chemical reaction was conducted in the presence of heparin to preserve basic residues within the heparin binding site from modifications. Results: AT treated by butanedione and selected for its high heparin affinity (AT-BD) was indeed modified on reactive Arg393 and thus exhibited decreased anticoagulant activity and increased heparin affinity. AT-BD was able to neutralize anticoagulant activity of heparin derivatives in vitro and in vivo and was devoid of intrinsic anticoagulant activity, as assessed by activated partial thromboplastin time assay. Conclusions: AT-BD appears to be as efficient as protamine to neutralize UFH in vivo but could be more largely used because it also reverses fondaparinux and LMWH.

Nonclinical Evaluation of Novel Cationically Modified Polysaccharide Antidotes for Unfractionated Heparin

“…In contrast to many studies focusing on heparin-binding properties of protamine alternatives, for example lactoferrin [ 33 ], methylene blue, vancomycin, hexadimethrine bromide [ 34 ], or chemically-modified inactive antithrombin [ 35 ], Dex40-GTMAC3 efficacy was confirmed in vitro and in vivo in both mice and rats. Nevertheless, we are aware that further primate studies and clinical trial are required to confirm efficacy and safety in humans.…”

The Toxicokinetic Profile of Dex40-GTMAC3—a Novel Polysaccharide Candidate for Reversal of Unfractionated Heparin

“…Moreover, it did not induce immune system response in contrast to protamine (Bakchoul et al, 2013 ), heparinase I (Stafford-Smith et al, 2005 ), lactoferrin (Wu et al, 1995 ) or low molecular weight protamine (Chang et al, 2001 ). The safety of other alternative UFH antidotes such as haxadimetrine bromide (Ransdell et al, 1965 ), methylene blue (Kikura et al, 1996 ; Ginimuge and Jyothi, 2010 ), vancomycin (Kikura et al, 1996 ), lactoferin (Wu et al, 1995 ), or chemically-modified inactive antithrombin (Fazavana et al, 2013 ) were not sufficiently examined in animals and they all failed in the later phases of drug discovery. Our present study provides toxicokinetic profile of Dex40-GTMAC3—a potential UFH reversal agent.…”

Management of severe perioperative bleeding

“…Although some research is ongoing, 413 currently there is no available drug acting as an antidote to fondaparinux. rFVIIa has been proposed to control severe bleeding, but limited data support this.…”