Pharmacologic inhibition of platelet vWF-GPIbα interaction prevents coronary artery thrombosis

Summary

Under high shear arterial blood flow von Willebrand Factor (vWF) binds the platelet receptor glycoprotein (GP) Ibα, leading to platelet adhesion, activation and thrombosis. Blockade of vWF-GPIbα interactions by GPG-290 was investigated in a canine model of coronary artery thrombosis alone and in combination with clopidogrel. GPG-290 (100 µg/kg, n=6; 500 µg/kg, n=6) prolonged time to thrombotic occlusion (TTO) to 105±34 and 156±23 (p<0.05) min, respectively compared to the saline treated control group (32±6min, n=6). Patency of the injured vessel was sustained in 1/6 (100µg/kg) and 3/6 vessels (500 µg/kg) 4 hours after injury, in contrast to 0/6 in the control group. There was an increase in bleeding after the 500 µg/kg dose, but only at the 1 hr time point. Clopidogrel was studied in two dosing regimens representing either a clinical pretreatment regimen (PTR) of 4.3 mg/kg on day –2 followed by 1.1 mg/kg daily for2 days prior to the procedure or pre-procedural loading dose regimen (LDR) of 4.3 mg/kg 3 hr pre-procedure. The PTR and LDR clopidogrel treatments prolonged TTO to 98.2±30.0 min and 136.1±39.5 min (p<0.05), and sustained patency in 1/6 and 4/8 vessels, respectively. However, template bleeding time in the LDR clopidogrel group was sustained higher than the control group. The combination of PTR clopidogrel and GPG-290 (100 µg/kg) prolonged TTO equivalent to LDR clopidogrel alone (141.4±35.1 min) and sustained patency in 3/7 dogs, without increased bleeding while LDR clopidogrel combined with 100 µg/kg GPG-290 prevented occlusion in 5/8 dogs and further prolonged TTO (173.5±32.6 min) but was associated with increased bleeding compared to control. GPG-290 is an antithrombotic agent that may be combined with lower doses of clopidogrel to yield similar antithrombotic efficacy as higher loading doses.

Keywords

Glycoprotein (GP) Ibα - platelet adhesion - platelet agglutination - thrombosis - von Willebrand factor (vWF)

All authors are employees of Wyeth Research.

• References

• 1 Lopez JA. The platelet glycoprotein Ib-IX complex. Blood Coagul Fibrinolysis 1994; 05: 97-119.
• 2 Roth GJ. Developing relationships: aterial platelet adhesion, glycoprotein Ib, and leucine-rich glycoproteins. Blood 1991; 77: 5-19.
• 3 Ruggeri ZM. Structure and function of von Willebrand factor. Thromb Haemost 1999; 82: 576-84.
• 4 Fujimura Y, Titani K, Holland LZ. et al. Von Willebrand factor. A reduced and alkylated 52/48-kDa fragment beginning at amino acid residue 449 contains the domain interacting with platelet glycoprotein Ib. J Biol Chem 1986; 261: 381-5.
• 5 Frossard M, Fuchs I, Leitner JM. et al. Platelet function predicts myocardial damage in patients with acute myocardial infarction. Circulation 2004; 110: 1392-7.
• 6 Eto K, Isshiki T, Yamamoto H. et al. AJVW-2, an anti-vWF monoclonal antibody, inhibits enahced platelet aggregation induced by high shear stress in platelet rich plasma from patients with acute coronary syndromes. Arterioscler Thromb Vasc Biol 1999; 19: 877-82.
• 7 Strony J, Beaudoin A, Brands D. et al. Analysis of shear stress and hemodynamic factors in a model of coronary artery stenosis and thrombosis. Am J Physiol 1993; 265: H1787-H1796.
• 8 McGhie AI, McNatt J, Ezov N. et al. Abolition of cyclic flow variations in stenosed, endothelium-injured coronary arteries in nonhuman primates with a peptide fragment (VCL) derived from human plasma von Willebrand factor – glycoprotein Ib binding domain. Circulation 1994; 90: 2976-81.
• 9 Kageyama S, Yamamoto H, Nakazawa H. et al. Pharmacokinetics and pharmacodynamics of AJW200, a humanized monoclonal antibody to von Willebrand factor, in monkeys. Arterioscler Thromb Vasc Biol 2002; 22: 187-92.
• 10 Kageyama S, Matsushita J, Yamamoto H. Effect of a humanized monoclonal antibody to von Willebrand factor in a canine model of coronary arterial thrombosis. Eur J Pharmacol 2002; 443: 143-9.
• 11 Strony J, Phillips M, Brands D. et al. Aurintricarboxylic acid ina canine model of coronary artery thrombosis. Circulation 1990; 81: 1106-14.
• 12 Dong J, Schade AJ, Romo GM. et al. Novel gain-offunction mutations of platelet glycoprotein Iba by valine mutagenesis in the Cys209-Cys248 disulfide loop. J Biol Chem 2000; 275: 27663-70.
• 13 Leon MB, Baim DS, Popma JJ. et al. A clinical trial comparing three antithrombotic-drug regimens after coronary-artery stenting. Stent Anticoagulation Restenosis Study Investigators. N Engl J Med 1998; 339: 1665-71.
• 14 Bertrand ME, Legrand V, Boland J. et al. Randomized multicenter comparison of conventional anticoagulation versus antiplatelet therapy in unplanned and elective coronary stenting. The full anticoagulation versus aspirin and ticlopidine (fantastic) study. Circulation 1998; 98: 1597-603.
• 15 Taniuchi M, Kurz HI, Lasala JM. Randomized comparison of ticlopidine and clopidogrel after intracoronary stent implantation in a broad patient population. Circulation 2001; 104: 539-43.
• 16 Bates ER, Lau WC, Bleske BE. Loading, pretreatment and interindividual variability issues with clopidogrel dosing. Circulation 2005; 111: 2557-9.
• 17 von Beckerath N, Taubert D, Pogatsa-Murray G. et al. Absorption, metabolization and antiplatelet effects of 300, 600 and 900-mg loading doses of clopidogrel. Circulation 2005; 112: 2946-50.
• 18 Sabatine MS, Cannon CP, Gibson CM. et al. Effect of clopidogrel pretreatment before percutaneous coronary intervention in patients with ST-elevation myocardial infarction treated with fibrinolytics: The PCIClaity Study. JAMA 2005; 294: 1224-32.
• 19 Ascione R, Ghosh A, Rogers CA. et al. In-hospital patients exposed to clopidogrel before coronary artery bypass graft surgery: a word of caution. Ann Thorac Surg 2005; 79: 1210-6.
• 20 Hennan JK, Elokdah H, Leal M. et al. Evaluation of PAI-039, a novel PAI-1 inhibitor, in a canine model of coronary artery thrombosis. J Pharmacol Exp Ther 2005; 314: 537-45.
• 21 Hennan JK, Hong TT, Shergill AK. et al. Intimatan prevents arterial and venous thrombosis in a canine model of deep vessel wall injury. J Pharmacol Exp Ther 2002; 301: 1151-6.
• 22 Hennan JK, Huang J, Barrett TD. et al. Effects of selective cyclooxygenase-2 inhibition on vascular responses and thrombosis in canine coronary arteries. Circulation 2001; 104: 820-5.
• 23 Hasan AAK, Schmaier AH, Warnock M. et al. Thrombostatin inhibits cyclic flow variations in stenosed canine coronary arteries. Thromb Haemost 2001; 86: 1296-304.
• 24 Vilahur G, Segales E, Salas E. et al. Effects of a novel platelet nitric oxide donor (LA816), aspirin, clopidogrel, and combined therapy in inhibiting flowand lesion-dependent thrombosis in the porcine ex vivo model. Circulation 2004; 110: 1686-93.
• 25 Thebault JJ, Kieffer G, Lowe GD. et al. Repeateddose pharmacodynamics of clopidogrel in healthy subjects. Semin Thromb Hemost 1999; 25: 9-14.
• 26 Gerschutz GP, Bhatt DL. Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) Study Investigators. The Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) study: to what extent should the results be generalizable?. Am Heart J 2003; 145: 595-601.
• 27 Mehta SR, Yusuf S. Clopidogrel in Unstable angina to prevent Recurrent Events (CURE) Study Investigators. The Clopidogrel in Unstable angina to prevent Recurrent Events (CURE) trial programme; rationale, design and baseline characteristics including a metaanalysis of the effects of thienopyridines in vascular disease. Eur HeartJ 2000; 02: 2033-41.
• 28 Yusuf S, Zhao F, Mehta SR. et al. Clopidogrel in Unstable Angina to Prevent Recurrent Events Trial Investigators. Effects of clopidogrel in addition to aspirin in patients with acute coronary syndromes without STsegment elevation. N Engl J Med 2001; 345: 494-502.
• 29 Read MS, Smith SV, Lamb MA. et al. Role of botrocetin in platelet agglutination: formation of an activated complex of botrocetin and von Willebrand factor. Blood 1989; 74: 1031-5.
• 30 Sugimoto M, Mohri H, McClintock RA. et al. Identification of discontinuous von Willebrand factor sequences involved in complex formation with botrocetin. A model for the regulation of von Willebrand factor binding to platelet glycoprotein Ib. J Biol Chem 1991; 266: 18172-8.
• 31 Bertrand ME, Rupprecht HJ, Urban P. et al. Doubleblind study of the safety of clopidogrel with and without a loading dose in combination with aspirin compared with ticlopidine in combination with aspirin after coronary stenting : the clopidogrel aspirin stent international cooperative study (CLASSICS). Circulation 2000; 102: 624-9.
• 32 Kastrati A, Mehilli J, Schuhlen H. et al. Intracoronary Stenting and Antithrombotic Regimen-Rapid Early Action for Coronary Treatment Study Investigators. A clinical trial of abciximab in elective percutaneous coronary intervention after pretreatment with clopidogrel. N Engl J Med 2004; 350: 232-8.