Anti‐thrombotic effects and bleeding risk of AJvW‐2, a monoclonal antibody against human von Willebrand factor

Kageyama, Shunsuke; Yamamoto, Hiroshi; Nagano, M; Arisaka, Harumi; Kayahara, Takashi; Yoshimoto, Ryota

doi:10.1038/sj.bjp.0701354

Cited by 70 publications

(52 citation statements)

References 27 publications

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“…In general, in flow chambers a more effective inhibition with vWF-GPIb inhibitors is obtained at higher shear rates, 11,12,36 which we also demonstrated here by finding a more pronounced effect of 6B4 on platelet adhesion to collagen when a higher shear was applied in a flow chamber; also, in vivo an arterial thrombus was more readily prevented than a venous one. 11 This implies that inhibition of GPIb would result especially in arterial effects, which in addition could result in less bleeding risk.…”

Section: Discussionsupporting

confidence: 67%

“…This finding supports data obtained with other GPIb-vWF-blocking agents (VCL, anti-vWF MoAb AJvW-2) that lengthened the bleeding time only moderately. 11,12,17,18 This finding is important and might provide a major advantage in the development of antithrombotic agents compared with GPIIb-IIIa antagonists, like ReoPro. 37 On the other hand, the GPIb-vWF interaction in contrast to the GPIIb-IIIa-fibrinogen interaction is the ultimate first step in platelet adhesion under fast blood flow.…”

Section: Discussionmentioning

confidence: 99%

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Antithrombotic Effect of Platelet Glycoprotein Ib–Blocking Monoclonal Antibody Fab Fragments in Nonhuman Primates

Cauwenberghs

Meiring

Vauterin

et al. 2000

ATVB

116

107

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Abstract-Platelet adhesion in arterial blood flow is mainly supported by the platelet receptor glycoprotein (GP) Ib, which interacts with von Willebrand factor (vWF) that is bound to collagen at the site of vessel wall injury. Antibody 6B4 is a monoclonal antibody (MoAb) raised against purified human GPIb. MoAb 6B4 inhibits both ristocetin-and botrocetin-induced, vWF-dependent human platelet agglutination. MoAb 6B4 furthermore blocks shear-induced adhesion of human platelets to collagen I. We studied the antithrombotic effect of this inhibitory murine MoAb 6B4 in a baboon model of arterial thrombosis. When injected into baboons, intact IgG and its F(abЈ) 2 fragments caused almost immediate thrombocytopenia, whereas injection of the Fab fragments alone did not. Fab fragments were subsequently used to investigate their in vivo effect on platelet deposition onto a thrombogenic device, consisting of collagen-rich, glutaraldehyde-fixed bovine pericardium (0.6 cm 2 ), at a wall shear rate ranging from 700 to 1000 s Ϫ1 . Baboons were either pretreated with Fabs to study the effect of inhibition on platelet adhesion or treated 6 minutes after placement of the thrombogenic device to investigate the effect on interplatelet cohesion. Pretreatment of the animals with bolus doses ranging from 80 to 640 g/kg Fab fragments significantly reduced 111 In-labeled platelet deposition onto the collagen surface by Ϸ43% to 65%. Only the highest dose caused a significant prolongation (doubling) of the bleeding time. Ex vivo ristocetin-induced platelet agglutination was equally reduced. Treatment with a bolus of 110 g/kg Fab fragments after a thrombus was allowed to form for 6 minutes had no effect on further platelet deposition. We therefore conclude that Fab fragments or derivatives of inhibitory anti-GPIb antibodies may be useful compounds to prevent thrombosis.

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Section: Discussionsupporting

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Antithrombotic Effect of Platelet Glycoprotein Ib–Blocking Monoclonal Antibody Fab Fragments in Nonhuman Primates

Cauwenberghs

Meiring

Vauterin

et al. 2000

ATVB

116

107

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“…12 The high shear-induced platelet aggregation and adhesion between platelets and collagen-coated glass in samples from healthy donors can be completely inhibited by AJvW-2 at a concentration of 10 g/mL, 12 which we used as Fab fragment in the following studies.…”

Section: Preparation Of Moabmentioning

confidence: 99%

“…11 The anti-human vWF MoAb AJvW-2 reacts with an epitope that is present in the A1 domain of vWF of humans as well as that of many other species, including the pig, rabbit, dog, guinea pig, and rat. 12 This antibody inhibits the vWF-mediated aggregation and adhesion of human blood platelets induced by high shear stress without increasing the risk of bleeding. 12 Assay of the ability of AJvW-2 to inhibit SIPA in the blood of patients with ACSs may therefore reveal whether antithrombotic therapy specifically targeting the vWF-GPIb interaction prevents new events in the coronary arteries.…”

mentioning

confidence: 99%

“…12 This antibody inhibits the vWF-mediated aggregation and adhesion of human blood platelets induced by high shear stress without increasing the risk of bleeding. 12 Assay of the ability of AJvW-2 to inhibit SIPA in the blood of patients with ACSs may therefore reveal whether antithrombotic therapy specifically targeting the vWF-GPIb interaction prevents new events in the coronary arteries. Thus, to clarify the involvement of the vWF-GPIb interaction in ACSs, we assayed the effect of AJvW-2 on both the vWF-and fibrinogen-dependent platelet aggregation in the blood of patients with UAP and AMI.…”

mentioning

confidence: 99%

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AJvW-2, an Anti-vWF Monoclonal Antibody, Inhibits Enhanced Platelet Aggregation Induced by High Shear Stress in Platelet-Rich Plasma From Patients With Acute Coronary Syndromes

Eto

Isshiki²,

Yamamoto³

et al. 1999

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Abstract-The platelet aggregation that is dependent on von Willebrand factor (vWF) is important in the thrombogenesisthat occurs under conditions of high shear stress, eg, during acute coronary syndromes (ACSs). A monoclonal antibody, AJvW-2, directed against the A1 domain of human vWF specifically blocks the interaction between plasma vWF and platelet glycoprotein (GP) Ib. To evaluate the association between the vWF-GPIb interaction and the enhanced shear-induced platelet aggregation (SIPA) observed in ACSs, we tested the effect of this antibody on platelet aggregation. Platelet-rich plasma was prepared from the citrated blood of 12 patients with unstable angina (UAP) and 20 patients with acute myocardial infarction (AMI) who were admitted within 3 hours of the onset of cardiac symptoms and from 18 controls. We observed the following: (1) 1.7-fold higher plasma levels of vWF and ristocetin cofactor activity in UAP patients and (2) 2.8-fold higher levels in the AMI group than in controls. Using a cone-and-plate viscometer, we measured the mean value of SIPA under high-shear conditions (108 dyne/cm 2 ) and found them to be 1.3-fold higher in the UAP group and 2.0-fold higher in the AMI group than in controls. The high SIPA in all groups was completely inhibited by 10 g/mL AJvW-2. Under low-shear conditions (12 dyne/cm 2 ), platelet aggregation was increased only in the AMI group, but this was unaffected by AJvW-2. We observed a significant correlation in both ACS groups between high SIPA and the plasma vWF level or vWF larger multimers. These findings suggest that the vWF-GPIb interaction is important in coronary occlusion and that inhibition of this interaction (with the use of AJvW-2) may prevent further events in the coronary arteries. A ctivation of platelets induced by physical shear stress or by physiological agonists is important in arterial thrombogenesis. 1,2 Increased levels of plasma von Willebrand factor (vWF) in patients with thrombotic disorders have suggested that this protein may be involved in thrombosis. For example, in survivors of acute myocardial infarction (AMI), the level of plasma vWF may be an index of the increased risk for reinfarction and mortality. 3 In addition, an enhanced plasma vWF concentration is thought to be an independent predictor of such acute coronary syndromes (ACSs) as unstable angina (UAP). 4 Most importantly, high physiological and/or pathological shear stress can induce vWF-mediated platelet aggregation in vitro 1,2,5,6 and may stimulate the interaction between plasma vWF and glycoprotein (GP) Ib on platelets in vivo, eg, in animal models with coronary artery occlusion. 7 To further clarify the molecular mechanism for arterial thrombogenesis and to seek an effective strategy for its prevention or treatment, efforts have focused on developing simple methods for monitoring vWFplatelet interactions in the blood of patients with ACSs. 2 The recent development of a cone-and-plate viscometer to monitor platelet aggregation under various shear conditions in the absence of an...

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Effects of acid exposure on the conformation, stability, and aggregation of monoclonal antibodies

et al. 2007

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Exposure of antibodies to low pH is often unavoidable for purification and viral clearance. The conformation and stability of two humanized monoclonal antibodies (hIgG4-A and -B) directed against different antigens and a mouse monoclonal antibody (mIgG1) in 0.1M citrate at acidic pH were studied using circular dichroism (CD), differential scanning calorimetry (DSC), and sedimentation velocity. Near- and far-UV CD spectra showed that exposure of these antibodies to pH 2.7-3.9 induced only limited conformational changes, although the changes were greater at the lower pH. However, the acid conformation is far from unfolded or so-called molten globule structure. Incubation of hIgG4-A at pH 2.7 and 3.5 at 4 degrees C over the course of 24 h caused little change in the near-UV CD spectra, indicating that the acid conformation is stable. Sedimentation velocity showed that the hIgG4-A is largely monomeric at pH 2.7 and 3.5 as well as at pH 6.0. No time-dependent changes in sedimentation profile occurred upon incubation at these low pHs, consistent with the conformational stability observed by CD. The sedimentation coefficient of the monomer at pH 2.7 or 3.5 again suggested that no gross conformational changes occur at these pHs. DSC analysis of the antibodies showed thermal unfolding at pH 2.7-3.9 as well as at pH 6.0, but with decreased melting temperatures at the lower pH. These results are consistent with the view that the antibodies undergo limited conformational change, and that incubation at 4 degrees C at low pH results in no time-dependent conformational changes. Titration of hIgG4-A from pH 3.5 to 6.0 resulted in recovery of native monomeric proteins whose CD and DSC profiles resembled those of the original sample. However, titration from pH 2.7 resulted in lower recovery of monomeric antibody, indicating that the greater conformational changes observed at this pH cannot be fully reversed to the native structure by a simple pH titration.

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Anti‐thrombotic effects and bleeding risk of AJvW‐2, a monoclonal antibody against human von Willebrand factor

Cited by 70 publications

References 27 publications

Antithrombotic Effect of Platelet Glycoprotein Ib–Blocking Monoclonal Antibody Fab Fragments in Nonhuman Primates

Antithrombotic Effect of Platelet Glycoprotein Ib–Blocking Monoclonal Antibody Fab Fragments in Nonhuman Primates

AJvW-2, an Anti-vWF Monoclonal Antibody, Inhibits Enhanced Platelet Aggregation Induced by High Shear Stress in Platelet-Rich Plasma From Patients With Acute Coronary Syndromes

Effects of acid exposure on the conformation, stability, and aggregation of monoclonal antibodies

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