The clot-targeting fusion molecule scFv(anti-LIBS)-TAP prolonged occlusion time comparably to enoxaparin and recombinant TAP, but without prolonging bleeding time in a mouse thrombosis model.
Does scFv(anti-LIBS)-TAP improve anticoagulative efficiency without prolonging bleeding time in a mouse thrombosis model?
A novel clot-targeting anticoagulant fusion molecule demonstrated effective antithrombotic activity without the typical associated increase in bleeding risk in a preclinical model.
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.
Stoll et al. (Fri,) conducted a other in Thrombosis. scFv(anti-LIBS)-TAP vs. enoxaparine, recombinant TAP, and nontargeted mutant-scFv-TAP was evaluated on Occlusion time and bleeding time. The clot-targeting fusion molecule scFv(anti-LIBS)-TAP prolonged occlusion time comparably to enoxaparin and recombinant TAP, but without prolonging bleeding time in a mouse thrombosis model.