Targeting ligand-induced binding sites on GPIIb/IIIa via single-chain antibody allows effective anticoagulation without bleeding time prolongation.

Abstract

OBJECTIVE:

Therapeutic anticoagulation is widely used, but limitations in efficacy and bleeding complications cause an ongoing search for new agents. However, with new agents developed it seems to be an inherent problem that increased efficiency is accompanied by an increase in bleeding complications. We investigate whether targeting of anticoagulants to activated platelets provides a means to overcome this association of potency and bleeding.

METHODS AND RESULTS:

Ligand-induced binding sites (LIBS) on fibrinogen/fibrin-binding GPIIb/IIIa represent an abundant clot-specific target. We cloned an anti-LIBS single-chain antibody (scFv(anti-LIBS)) and genetically fused it with a potent, direct factor Xa (fXa) inhibitor, tick anticoagulant peptide (TAP). Specific antibody binding of fusion molecule scFv(anti-LIBS)-TAP was proven in flow cytometry; anti-fXa activity was demonstrated in chromogenic assays. In vivo anticoagulative efficiency was determined by Doppler-flow in a ferric chloride-induced carotid artery thrombosis model in mice. ScFv(anti-LIBS)-TAP prolonged occlusion time comparable to enoxaparine, recombinant TAP, and nontargeted mutant-scFv-TAP. ScFv(anti-LIBS)-TAP revealed antithrombotic effects at low doses at which the nontargeted mutant-scFv-TAP failed. In contrast to the other anticoagulants tested, bleeding times were not prolonged by scFv(anti-LIBS)-TAP.

CONCLUSIONS:

The novel clot-targeting approach of anticoagulants via single-chain antibody directed against a LIBS-epitope on GPIIb/IIIa promises effective anticoagulation with reduced bleeding risk.

• Authors: Patrick Stoll, Nicole Bassler, Christoph E Hagemeyer, Steffen U Eisenhardt, Yung Chih Chen, Rene Schmidt, Meike Schwarz, Ingo Ahrens, Yasuhiro Katagiri, Benedikt Pannen, Christoph Bode, Karlheinz Peter
• Journal: Arteriosclerosis, thrombosis, and vascular biology (Arterioscler Thromb Vasc Biol) Vol. 27 Issue 5 Pg. 1206-12 (May 2007) ISSN: 1524-4636 [Electronic] United States
• PMID: 17322097 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Monoclonal
• Epitopes
• Immunoglobulin Fragments
• Immunologic Factors
• Ligands
• Platelet Glycoprotein GPIIb-IIIa Complex
• immunoglobulin Fv

Topics

• Animals
• Antibodies, Monoclonal (therapeutic use)
• Binding Sites, Antibody
• Blood Platelets (drug effects)
• Blotting, Western
• Epitopes
• Flow Cytometry
• Gene Expression
• Hemorrhage (epidemiology, etiology)
• Humans
• Hybridomas (pathology)
• Immunoglobulin Fragments (genetics, immunology, therapeutic use)
• Immunologic Factors (therapeutic use)
• Ligands
• Mice
• Mice, Inbred C57BL
• Platelet Aggregation (drug effects)
• Platelet Glycoprotein GPIIb-IIIa Complex (drug effects, immunology)
• Protein Binding
• Risk Factors
• Thrombosis (blood, complications, drug therapy)