Is thrombin generation the new rapid, reliable and relevant pharmacological tool for the development of anticoagulant drugs?

Robert, Séverine; Ghiotto, J.; Pirotte, Bernard; David, Jean-Louis; Masereel, Bernard; Pochet, Lionel; Dogné, Jean‐Michel

doi:10.1016/j.phrs.2008.12.003

Cited by 49 publications

(63 citation statements)

References 35 publications

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“…31 Enoxaparin (Sanofi-Aventis) was used at 0.2 U/mL; and hirudin, a thrombin inhibitor (Sigma-Aldrich) was used at 5 to 20 U/mL, doses used previously to block thrombin generation or prolong activated clotting time and APPT. [32][33][34] …”

Section: Coagulation Inhibitorsmentioning

confidence: 99%

Coagulation-induced shedding of platelet glycoprotein VI mediated by factor Xa

Al‐Akchar

Grigoriadis

Tran

et al. 2011

Blood

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This study evaluated shedding of the platelet collagen receptor, glycoprotein VI (GPVI) in human plasma. Collagen or other ligands induce metalloproteinasemediated GPVI ectodomain shedding, generating approximately 55-kDa soluble GPVI (sGPVI) and approximately 10-kDa platelet-associated fragments. In the absence of GPVI ligands, coagulation of platelet-rich plasma from healthy persons induced GPVI shedding, independent of added tissue factor, but inhibitable by metalloproteinase inhibitor, GM6001. Factor Xa (FXa) common to intrinsic and tissue factor-mediated coagulation pathways was critical for sGPVI release because (1) shedding was strongly blocked by the FXa-selective inhibitor rivaroxaban but not FIIa (thrombin) inhibitors dabigatran or hirudin; (2) Russell viper venom that directly activates FX generated sGPVI, with complete inhibition by enoxaparin (inhibits FXa and FIIa) but not hirudin; (3) impaired GPVI shedding during coagulation of washed platelets resuspended in FX-depleted plasma was restored by adding purified FX; and (4) purified FXa induced GM6001-inhibitable GPVI shedding from washed platelets. In 29 patients with disseminated intravascular coagulation, mean plasma sGPVI was 53.9 ng/mL (95% confidence interval, 39.9-72.8 ng/mL) compared with 12.5 ng/mL (95% confidence interval, 9.0-17.3 ng/mL) in thrombocytopenic controls (n ‫؍‬ 36, P < .0001), and 14.6 ng/mL (95% confidence interval, 7.9-27.1 ng/mL) in healthy subjects (n ‫؍‬ 25, P ‫؍‬ .002). In conclusion, coagulation-induced GPVI shedding via FXa down-regulates GPVI under procoagulant conditions. FXa inhibitors have an unexpected role in preventing GPVI down-regulation. (Blood. 2011;117(14):3912-3920) IntroductionIn atherothrombotic disease, thrombus formation at arterial shear rates involves initial platelet adhesion and activation at sites of vascular injury/collagen exposure, and activation of coagulation that generates active thrombin and stabilizes the thrombus by fibrin. 1 Bidirectional regulation of platelet function and coagulation is important in both the pathology of atherothrombotic diseases, such as heart attack or acute ischemic stroke, and in the clinical use of antiplatelet or anticoagulant drugs. [2][3][4][5] The platelet collagen receptor, glycoprotein (GP)VI, is a promising target of antithrombotic therapy because it is not only critical for initiating platelet activation and thrombus formation at arterial shear rates but also promotes thrombus growth and stability because of effects on coagulation. [6][7][8][9] In experimental models, depletion of platelet GPVI results in decreased responsiveness to collagen, impaired procoagulant activity and thrombin generation ex vivo and in vivo, and protection from tissue factor (TF)-induced thromboembolism. 9-11 GPVI agonists also increase phosphatidylserine exposure and microparticle formation, whereas stimulation of platelets with a GPVI ligand (convulxin) and thrombin increase active factor X (FXa) and thrombin, regulated by a subpopulation of platelets with increased binding of c...

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Section: Coagulation Inhibitorsmentioning

confidence: 99%

Coagulation-induced shedding of platelet glycoprotein VI mediated by factor Xa

Al‐Akchar

Grigoriadis

Tran

et al. 2011

Blood

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“…29 Compared with the PT assay, the TG test appears to be more reliable and to more directly reflect bleeding, at least in patients with various coagulation factor deficiencies. 26,30,46 When the sensitivity and quality control of the TG assay are optimized with modifications to minimize variability, 31,42,47 as in the case of the current trial, then TG may provide a more accurate measure of coagulation status. Technologic advancements have also increased the relevance of TEG in the clinical assessment of bleeding and thrombotic conditions 32 and in the monitoring of clot dynamics of both rFVIIa and antagonists to rFVIIa.…”

Section: Discussionmentioning

confidence: 99%

“…24 Clotting assays (eg, aPTT, PT, and INR) have shown limited correlation to bleeding, because they are ex vivo assessments performed in citrated plasma lacking activated platelets. [25][26][27][28] Further, they only describe the initial stage of coagulation. In contrast, TEG can provide continuous coagulation profiles of clot formation in whole blood from initiation to final clot strength, whereas TG can determine the ability to generate the central coagulation enzyme, thrombin.…”

Section: Introductionmentioning

confidence: 99%

Exploratory study on the reversal of warfarin with rFVIIa in healthy subjects

Skolnick

Mathews

Khutoryansky

et al. 2010

Blood

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The use of warfarin has a well-known bleeding risk. Recombinant activated factor VII (rFVIIa) is a non-plasma-derived, rapid-acting, and rapidly infused potential treatment. This randomized, singlecenter, placebo-controlled, double-blinded, dose-escalation, exploratory phase 1 trial assessed safety and effects of rFVIIa in reversing warfarin-induced changes in bleeding and coagulation parameters, using a punch biopsy-induced bleeding model in healthy subjects. The effects of warfarin (experiment 1) and rFVIIa (5-80 g/kg; experiment 2) were evaluated.Outcomes were bleeding duration, blood loss, coagulation parameters, and safety. Warfarin treatment significantly increased bleeding duration and blood loss from pretreatment (experiment 1, 12 subjects). However, these parameters after rFVIIa treatment were not significantly different from placebo (experiment 2, 85 subjects). Mean activated partial thromboplastin time, prothrombin time, and international normalized ratio were reduced from warfarin-elevated levels. rFVIIa (80 g/kg) significantly reversed warfarin effects on all thromboelastography parameters, compared with placebo (P < .05), and returned the thrombin generation speed to baseline. There were no thromboembolic or serious adverse events. In this exploratory trial, the reversal of warfarin effects was observed in the thromboelastography, thrombin generation, and clotting assays. However, this reversal did not translate to improvements in the bleeding model parameters evaluated in the punch biopsy model. Trial registration is exempt (phase 1). (Blood. 2010;116(5):693-701)

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“…The coagulation cascade is triggered by the tissue factor pathway by addition of tissue factor, phospholipids, and calcium chloride, eliminating interference from in vitro contact factor activation, and providing the optimum reagent conditions for using CAT as a global test for hemostasis assessment in clinical practice [14]. This assay is known to detect even minor alterations of coagulation, and is sensitive enough to test thrombin activity after anticoagulants such as hirudin [20], heparin [21,22], and novel antithrombin agents including melagatran [23,24], and ximelagatran [24]. Therefore, some comparative studies of the impact of various antithrombins on thrombin indices are warranted as well.…”

Section: Discussionmentioning

confidence: 99%

Effects of dabigatran in vitro on thrombin biomarkers by Calibrated Automated Thrombography in patients after ischemic stroke

Serebruany

Sani

Lynch

et al. 2011

J Thromb Thrombolysis

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Randomized trials suggest superior and safe stroke prevention in patients with atrial fibrillation after anticoagulation with dabigatran (D) at a 150 mg BID as described in the RE-LY prospective randomized open-label trial when compared to warfarin. Thrombin generation (TG) is a cornerstone of coagulation cascade, and represents a critical biomarker of atherothrombosis. We, therefore, sought to define the effect of D in escalating concentrations on the time course of TG using the Calibrated Automated Thrombogram(®) (CAT) technology in patients after ischemic stroke. Serial plasma samples were obtained from 20 patients with ischemic stroke documented by neuroimaging, who were treated with aspirin for at least 30 days. The impact of 0.1, 0.23, 0.46, 0.69 mM D in platelet-poor plasma (PPP) on TG indices was assessed using fluorogenic substrate CAT device. The following integrated CAT parameters: TGmax, start time (t-start) peak time (t-peak), and mean time (t-mean) were calculated for each D dose and compared with those of the vehicle. Preincubation of PPP with D resulted in dose-dependent significant inhibition of most TG indices. The TGmax was gradually reduced from 447 ± 21 nM at baseline and reach significance for 0.46 mM D (355 ± 44 nM, P = 0.03); and decreased further at 0.69 mM D to 302 ± 27 nM (P = 0.01). The t-peak has been achieved 2-3 times later than after vehicle already at 0.23 nM D. The t-start was delayed 3-4 fold starting from 0.23 mM concentration of D (P < 0.001 for all), but not different from D 0.1 mM (1.5 vs. 1.6; P = 0.34). The t-mean was not significantly affected by D. D in vitro impacts indices of TG predominantly by dose dependent inhibition of endogenous TG, and delayed thrombin production. This preliminary evidence, while intriguing, requires confirmation in post-stroke patients receiving orally dosed D in order to determine whether these findings are clinically relevant.

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Is thrombin generation the new rapid, reliable and relevant pharmacological tool for the development of anticoagulant drugs?

Cited by 49 publications

References 35 publications

Coagulation-induced shedding of platelet glycoprotein VI mediated by factor Xa

Coagulation-induced shedding of platelet glycoprotein VI mediated by factor Xa

Exploratory study on the reversal of warfarin with rFVIIa in healthy subjects

Effects of dabigatran in vitro on thrombin biomarkers by Calibrated Automated Thrombography in patients after ischemic stroke

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