Anti-Human von Willebrand Factor Monoclonal Antibody AJvW-2 Prevents Thrombus Deposition and Neointima Formation After Balloon Injury in Guinea Pigs

Abstract

Abstract-Immediately after angioplasty, platelet adhesion to the injured arterial wall and subsequent release of various mitogens may contribute to neointima formation. The purpose of this study was to evaluate the inhibitory effect of AJvW-2, a monoclonal antibody against human von Willebrand factor (vWF), on neointima formation in a guinea pig model. The carotid artery was injured with a balloon catheter, and AJvW-2 was administered by a single bolus injection. AJvW-2 dose-dependently prevented neointima formation 14 days after injury. Significant inhibition was observed at 1.8 mg/kg, at which dose significant inhibition of platelet aggregation was achieved for 2 days. By elastic-Masson staining, organized thrombi were observed in the neointimal lesion on day 14. The thrombus area was significantly correlated with neointimal thickness. Furthermore, thrombus deposition, immunostained for vWF and fibrin(ogen), was observed on the media immediately after balloon injury. AJvW-2 significantly reduced the deposition of both adhesive proteins and reduced the incidence of organized thrombus formation, which might affect subsequent neointima formation. However, the proliferation of cultured smooth muscle cells was not affected by AJvW-2. These results suggest that AJvW-2 prevents neointima formation by inhibition of initial platelet-mediated thrombus formation rather than by direct inhibition of smooth muscle cell proliferation. (Arterioscler Thromb Vasc

Contribution of von Willebrand Factor to Thrombus Formation on Neointima of Rabbit Stenotic Iliac Artery Under High Blood-Flow Velocity

“…Moreover, certain in vivo studies have indicated that inhibition of vWF activity attenuated neointimal growth in animal models. 15,44 These reports suggest that increased synthesis and/or deposition of vWF in the neointima might stimulate further neointimal development and plaque formation. On the other hand, a study of von Willebrand disease in pigs has indicated that vWF was not essential for neointimal development in normal carotid and femoral arteries.…”

Shielding the front-strand β3 of the von Willebrand factor A1 domain inhibits its binding to platelet glycoprotein Ibα

“…[21][22][23][24][25] The humanized form of the blocking mAb AJvW-2 thus constitutes a potential therapeutic agent for the prevention of acute thrombosis in clinical practice. In this study, we tested the hypothesis that the antibody reacts with a highly conserved epitope on human VWF A1, critical for binding to GPIb␣.…”

“…This antibody binds to the A1 domain of VWF derived from several species, recognizing an epitope conserved in all these species. [21][22][23][24][25] We have used this property to identify the amino acid residues recognized by AJvW-2 and to study the interaction between VWF and GPIb␣ in more detail. By using a series of recombinant A1 domain mutants, which were designed following sequence comparison between murine, human, canine, porcine, and rabbit VWF, we found that AJvW-2 does indeed bind to the front side of strand ␤3 of the A1 domain, involving sequences that are part of both the binding pocket for GPIb␣ and the heparin-binding site.…”

Antithrombotic drug candidate ALX-0081 shows superior preclinical efficacy and safety compared with currently marketed antiplatelet drugs

“…Therefore, it is expected that drugs inhibiting this interaction between VWF and platelets show an improved safety profile with respect to bleeding tendency. Indeed, the antithrombotic effect of several compounds targeting the gpIb-VWF-A1-axis, like aurintricarboxylic acid, 10-12 recombinant VWF fragments, 10,13-16 a recombinant gpIb chimeric protein, 17,18 anti-VWF mAbs, [19][20][21][22][23][24][25][26][27] and an anti-VWF aptamer 28 has been demonstrated in vitro and in vivo, without increasing the bleeding risk. 13,[16][17][18]21,23,25,28,29 Nevertheless, until now only 3 drug candidates have been evaluated in humans, including ALX-0081.…”