Inhibition of the von Willebrand (VWF)–collagen interaction by an antihuman VWF monoclonal antibody results in abolition of in vivo arterial platelet thrombus formation in baboons

Abstract

The interaction between collagen, von Willebrand factor (VWF), and glycoprotein Ib is the first step in hemostasis and thrombosis especially under high shear conditions. We studied the inhibition of the VWF-collagen interaction by using an antihuman VWF monoclonal antibody 82D6A3 to prevent arterial thrombosis in baboons to develop a new kind of antithrombotic strategy and determine for the first time experimental in vivo data concerning the importance of the collagen-VWF interaction. We used a modified Folts model to study the antithrombotic efficacy of 82D6A3, where cyclic flow reductions (CFRs) were measured in the femoral artery. Administering a dose of 100, 300, and 600 g/kg resulted in a 58.3%, 100%, and 100% reduction in the CFRs, respectively. When 100 g/kg 82D6A3 was infused into the baboons, 80% of VWF-A3 domain was occupied, corresponding to 30% to 36% ex vivo inhibition of VWF binding to collagen, with no prolongation of the bleeding time. The bleeding time was also not significantly prolonged when the CFRs were abolished at doses of 300 g/kg and 600 g/kg. At these doses 100% of VWF was occupied by the antibody and 100% ex vivo inhibition of the VWF-collagen binding was observed. 82D6A3 has a high affinity for VWF; after 48 hours still 68% VWF (300g/kg) was occupied with a pharmacologic effect up to 5 hours after administration (80%-100% occupancy). In conclusion, these results clearly indicate that the VWFcollagen interaction is important in vivo in thrombosis under high shear conditions and thus might be a new target for preventing arterial thrombosis. (Blood. 2002;99:3623-3628)

A Consensus Tetrapeptide Selected by Phage Display Adopts the Conformation of a Dominant Discontinuous Epitope of a Monoclonal Anti-VWF Antibody That Inhibits the von Willebrand Factor-Collagen Interaction

“…We recently demonstrated that inhibiting the VWF-collagen interaction by 82D6A3 results in an effective antithrombotic therapy when tested in baboons using a modified Folts model in the femoral artery (33), thereby confirming that the VWF-collagen interaction has a relevant physiological role.…”

“…We raised a monoclonal antibody (mAb), 82D6A3, against human VWF that prevents the binding of VWF to collagen (24) and that is antithrombotic in a baboon arterial thrombosis model (33). Since a previous effort to determine the epitope of 82D6A3 using phage display, was not successful (34,35), we repeated this study using less stringent selection criteria.…”

Implications for collagen I chain registry from the structure of the collagen von Willebrand factor A3 domain complex

“…The VWF-collagen interaction is a potential target for therapeutic intervention (41). Our crystallographic data reveal that although the VWF-binding site overlaps those of DDR2 and SPARC marked differences exist suggesting it should be possible to specifically block the VWF-binding site on collagen.…”

Mapping the Collagen-binding Site in the von Willebrand Factor-A3 Domain

“…Surprisingly, these mutations caused no (32) or only moderate (33) bleeding symptoms, which questioned the relevance of the A3 domain for immobilization of VWF to the vascular matrix (32). However, Wu et al (34) recently showed that collagen binding by the A3 domain is relevant because an antibody blocking the VWF-A3-collagen interaction prevented the formation of platelet-rich thrombi and prolonged the skin bleeding time at high doses. Further investigations are required to reconcile these conflicting observations and to establish the physiological importance of VWF-A3 in platelet adhesion.…”