Effect of a humanized monoclonal antibody to von Willebrand factor in a canine model of coronary arterial thrombosis

The purpose of this study was to investigate the antithrombotic effect and bleeding time prolongation of AJW200, a humanized monoclonal antibody to von Willebrand factor (vWF), in a canine model of coronary arterial thrombosis. AJW200 significantly inhibited cyclic flow reductions, as well as botrocetin-induced platelet aggregation, at 0.1 mg/kg. A significant prolongation of bleeding time was observed at 0.3–1 mg/kg. Approximately 50% occupancy of vWF (approximately 0.7 μg/ml AJW200 in plasma) and 80–100% occupancy (approximately 20 μg/ml AJW200 in plasma) were needed for the antithrombotic effect and the extensive prolongation of bleeding time, respectively. On the contrary, the minimal effective dose of abciximab (0.8 mg/kg) was associated with a significant prolongation of bleeding time. These results suggest that the pharmacological blockade of platelet glycoprotein (GP) Ib-vWF interaction with AJW200 results in a safer antithrombotic profile than platelet GPIIb/IIIa blockade with abciximab in dogs.