Fibrin-targeted direct factor Xa inhibition: construction and characterization of a recombinant factor Xa inhibitor composed of an anti-fibrin single-chain antibody and tick anticoagulant peptide

2004 ◽  
Vol 92 (07) ◽  
pp. 47-53 ◽  
Author(s):  
Uta Weirich ◽  
Nicole Bassler ◽  
Meike Schwarz ◽  
Marschall Runge ◽  
Christoph Bode ◽  
...  
Keyword(s):  
Factor Xa ◽  
Coagulation Cascade ◽  
Bleeding Complications ◽  
Scale Production ◽  
Single Chain ◽  
Single Chain Antibody ◽  
Factor Xa Inhibition ◽  
N Terminus ◽  
Fxa Inhibitor ◽  
Tick Anticoagulant Peptide

SummaryWe investigated whether the direct fXa inhibitor tick anticoagulant peptide (TAP) can be N-terminally coupled to a clot-targeting, single-chain antibody specific for fibrin (scFv59D8). Due to its unique position at the convergence point of the intrinsic and extrinsic pathways early in the coagulation cascade, factor Xa (fXa) represents an attractive therapeutic target. In contrast to indirect inhibitors, direct fXa inhibitors effectively inhibit clotbound and prothrombinase-associated fXa. Targeting of direct fXa inhibitors to clots promises to enhance local anticoagulative potency and to reduce systemic anticoagulation which potentially results in less bleeding complications. TAP is a highly potent fXa inhibitor. Since its N-terminus is essential for antifXa activity, it was a challenging question, whether TAP will be active as a N-terminally coupled fusion molecule. Two step affinity chromatography with Ni2+ and β15-22-peptide of human fibrin results in a pure 36 kDa protein, which was tested for its targeting function and anti-fXa activity. The recombinant fusion did not destroy the function of the fusion partners. Antibody binding function was on a par with the parent molecule. TAP activity was partially reduced, arguing that a free N-terminus is not required for anti-fXa activity, but is important for maximal potency. In human whole blood clots, scFv59D8-TAP revealed anticoagulative properties at concentrations (200 to 500 nM) where non-targeted TAP did not reveal anticoagulative activity at all. In summary, scFv59D8-TAP constitutes a promising new anticoagulant with fibrin-targeted factor Xa inhibition. The production in E. coli and the established purification methods are a solid basis for a modern, large scale production at low cost and reproducible activity.

Inhibition of Thrombin Generation in Plasma by Inhibitors of Factor Xa

1997 ◽  
Vol 78 (04) ◽  
pp. 1215-1220 ◽  
Author(s):  
D Prasa ◽  
L Svendsen ◽  
J Stürzebecher
Keyword(s):  
Thrombin Generation ◽  
Factor Xa ◽  
Thrombin Inhibitors ◽  
Thrombin Inhibitor ◽  
Thrombin Generation Assay ◽  
Ic50 Values ◽  
Fxa Inhibitor ◽  
20 Nm ◽  
Tick Anticoagulant Peptide ◽  
Inhibition Of Thrombin

SummaryA series of inhibitors of factor Xa (FXa) were investigated using the thrombin generation assay to evaluate the potency and specificity needed to efficiently block thrombin generation in activated human plasma. By inhibiting FXa the generation of thrombin in plasma is delayed and decreased. Inhibitor concentrations which cause 50 percent inhibition of thrombin generation (IC50) correlate in principle with the Ki values for inhibition of free FXa. Recombinant tick anticoagulant peptide (r-TAP) is able to inhibit thrombin generation with considerably low IC50 values of 49 nM and 37 nM for extrinsic and intrinsic activation, respectively. However, the potent synthetic, low molecular weight inhibitors of FXa (Ki values of about 20 nM) are less effective in inhibiting the generation of thrombin with IC50 values at micromolar concentrations.The overall effect of inhibitors of FXa in the thrombin generation assay was compared to that of thrombin inhibitors. On the basis of similar Ki values for the inhibition of the respective enzyme, synthetic FXa inhibitors are less effective than thrombin inhibitors. In contrast, the highly potent FXa inhibitor r-TAP causes a stronger reduction of the thrombin activity in plasma than the most potent thrombin inhibitor hirudin.

scholarly journals Dual Pathway Inhibition with Low-Dose Direct Factor Xa Inhibition after Acute Coronary Syndromes—Why Is It Not Used in Clinical Practice?

2018 ◽  
Vol 118 (09) ◽  
pp. 1528-1534 ◽  
Author(s):  
Uwe Zeymer ◽  
Benedikt Schrage ◽  
Dirk Westermann
Keyword(s):  
Clinical Practice ◽  
Secondary Prevention ◽  
Low Dose ◽  
Factor Xa ◽  
Bleeding Complications ◽  
Direct Factor ◽  
Anti Platelet Therapy ◽  
Factor Xa Inhibition ◽  
Dual Pathway ◽  
Pathway Inhibition

AbstractThe optimal anti-thrombotic therapy for secondary prevention after an acute coronary syndrome is still a matter of debate. While current guidelines recommend dual anti-platelet therapy with aspirin and a P2Y12 inhibitor over 12 months especially in patients with stent implantation, the value of prolonged anticoagulation is still controversial. In the ATLAS-TIMI 52 trial, a low-dose direct factor Xa inhibition with rivaroxaban compared with placebo reduced the combined primary endpoint of cardiovascular mortality, myocardial infraction and stroke with an increase in major bleeding complications. This article discusses the value and problems of adding low-dose rivaroxaban to anti-platelet therapy as secondary prevention measure after an acute myocardial infarction. It will describe the pros and cons of intensified anti-platelet therapy versus dual pathway inhibition and give recommendations for different patient groups in clinical practice.

Comparative efficacy and safety of the novel oral anticoagulants dabigatran, rivaroxaban and apixaban in preclinical and clinical development

2010 ◽  
Vol 103 (03) ◽  
pp. 572-585 ◽  
Author(s):  
Mike Ufer
Keyword(s):  
Oral Anticoagulants ◽  
Safety Data ◽  
Factor Xa ◽  
Clinical Development ◽  
Phase Iii ◽  
Coagulation Cascade ◽  
Bleeding Complications ◽  
Thrombin Inhibitor ◽  
Factor Xa Inhibitor ◽  
Efficacy And Safety

SummaryTherapeutic oral anticoagulation is still commonly achieved by administration of warfarin or other vitamin K antagonists that are associated with an untoward pharmacokinetic / pharmacodynamic (PK/PD) profile leading to a high incidence of bleeding complications or therapeutic failure. Hence, there is an unmet medical need of novel easy-to-use oral anticoagulants with improved efficacy and safety. Recent developments include the identification of non-peptidic small-molecules that selectively inhibit certain serine proteases within the coagulation cascade. Of these, the thrombin inhibitor dabigatran and factor Xa inhibitor rivaroxaban have recently been licensed for thromboprophylaxis after orthopaedic surgery mainly in Europe. In addition, the factor Xa inhibitor apixaban is in late-stage clinical development. Each drug is prescribed at fixed doses without the need of anticoagulant monitoring. Phase III trials in orthopaedic patients essentially resulted in non-inferior efficacy of dabigatran and superior efficacy of rivaroxaban over enoxaparin without any marked differences of drug safety, while apixaban data is still controversial. However, alterations of rivaroxaban and apixaban pharmacokinetics upon interactions with inhibitors and inducers of CYP3A4 or P-glycoprotein may complicate the use of these compounds in daily practice, whereas dabigatran elimination largely depends on renal function. Hence, this review reports PK/PD, efficacy and safety data of dabigatran, rivaroxaban and apixaban throughout preclinical and clinical development.

In Vitro Characteristics, Anticoagulant Effects and In Vivo Antithrombotic Efficacy of a Novel, Potent and Orally Active Direct Factor Xa Inhibitor, DU-176b.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1862-1862 ◽  
Author(s):  
Yoshiyuki Morishima ◽  
Taketoshi Furugohri ◽  
Koji Isobe ◽  
Yuko Honda ◽  
Chikako Matsumoto ◽  
...  
Keyword(s):  
Oral Administration ◽  
Factor Xa ◽  
Coagulation Cascade ◽  
Venous Stasis ◽  
Factor Xa Inhibitor ◽  
Fxa Inhibitor ◽  
Antithrombotic Efficacy ◽  
Orally Active

Abstract Factor Xa (FXa) is a key serine protease in the coagulation cascade and is a promising target enzyme for developing a new antithrombotic agent. Our first clinical candidate for a small molecular direct FXa inhibitor DX-9065a potently inhibits FXa (Ki = 41 nM) and exerts antithrombotic effects in animal models. However, due to its poor bioavailability (10% in monkeys) the compound is used only as an injectable formulation in clinical studies. Here we report in vitro characteristics of serine proteases inhibition, anticoagulant effects and in vivo antithrombotic efficacy of DU-176b, a novel, potent and orally active direct FXa inhibitor. DU-176b competitively inhibited human FXa with a Ki value of 0.561 nM, indicating 70-fold increase in FXa inhibitory activity compared with DX-9065a. DU-176b demonstrated 10,000-fold selectivity relative to inhibition of thrombin (Ki = 6.00 μM), and had no effects on the enzymatic activities of factor VIIa, t-PA, plasmin, trypsin and chymotrypsin. In human plasma, DU-176b prolonged prothrombin time (PT) and activated partial thromboplastin time (APTT) in a concentration-dependent manner. Its concentrations for doubling these clotting times were 0.256 and 0.508 μM, respectively. After oral administration of DU-176b to rats, significant anti-Xa activity was observed in plasma over 4 h. The oral bioavailability of DU-176b (approximately 50%) was significantly higher than that of DX-9065a (10%) in monkeys. The antithrombotic efficacy of DU-176b was examined by oral administration to rats 30 minutes prior to thrombogenic stimuli. In a venous stasis thrombosis model, DU-176b (0.5 – 12.5 mg/kg, p.o.) dose-dependently inhibited thrombus formation, prolonged PT, and revealed plasma anti-Xa activity. DU-176b also exerted significant anticoagulant effect in a rat model of tissue factor-induced disseminated intravascular coagulation at doses of 0.1 – 2.5 mg/kg, p.o. These results demonstrate that DU-176b is a potent and selective factor Xa inhibitor that possesses antithrombotic effect after oral administration. DU-176b has the potential to be clinically useful for prophylaxis and treatment of several thrombotic diseases.

Amplified anticoagulant activity of tissue factor-targeted thrombomodulin

2006 ◽  
Vol 96 (09) ◽  
pp. 317-324 ◽  
Author(s):  
Chenliang Wu ◽  
Jon Vincelette ◽  
Baby Martin-McNulty ◽  
Serene Alexander ◽  
Brent Larsen ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Neutralizing Antibodies ◽  
Factor Viia ◽  
Anticoagulant Activity ◽  
Coagulation Cascade ◽  
Control Group ◽  
Therapeutic Effects ◽  
Single Chain ◽  
Single Chain Antibody

SummaryTissue factor (TF) exposure isa potent pro-thrombotic trigger that initiates activation of the coagulation cascade, while thrombomodulin (TM) is a potent anticoagulant protein that limits the extent of activation. Both TF neutralizing antibodies and soluble TM (sTM) are effective anticoagulants. We have developed a novel anticoagulant fusion protein, Ab(TF)-TM, by fusing a TF-neutralizing single-chain antibody, Ab(TF), to an active fragment of TM. Ab(TF)-TM is a novel anticoagulant targeting to sites of TF exposure with a dual mechanism of action. The Ab(TF) portion of the molecule inhibits TF/factor VIIa mediated activation of FIX and FX, and the TM portion of the molecule acts as a cofactor for activation of protein C. In-vitro coagulation assays show that Ab(TF)-TM more potently inhibits TF-initiated coagulation (prothrombin time) than can its individual components, Ab(TF) (20-fold) and sTM (80-fold) alone, or in combination (10-fold). In contrast, the potency of Ab(TF)-TM in the activated partial thromboplastin and thrombin clotting time assays was similar to sTM alone. Ina rat model of disseminated intravascular coagulation (DIC), intravenous injection of a human TF-containing thromboplastin reagent (0.5 ml/kg) resulted in an immediate death in ∼60% of the animals and a clinical score of ∼2.5. Pre-injection of Ab(TF)-TM or Ab(TF) and sTM, given alone or in combination, showed dose-dependent efficacy. At a dose of 0.7 nmol/kg, Ab(TF)-TM completely prevented death and reduced clinical scores by 79%, while neither Ab(TF) nor sTM, given alone or in combination, showed significant therapeutic effects. Calculated effective doses that reduced mortality by 50% relative to that in the control group (ED50, nmol/kg) were 0.21 for Ab(TF)-TM, 3.2 for an equimolar mixture of Ab(TF) and sTM, 4.3 for sTM and 20 for Ab(TF). Thus, Ab(TF)-TM presented 10– to 100-fold enhancement of the anticoagulant potency, relative to the ED50 in Ab(TF) and sTM given either alone or in combination, in a rat DIC model.

scholarly journals Construction and Functional Evaluation of a Single-Chain Antibody Fusion Protein With Fibrin Targeting and Thrombin Inhibition After Activation by Factor Xa

Circulation ◽  
2000 ◽  
Vol 101 (10) ◽  
pp. 1158-1164 ◽  
Author(s):  
Karlheinz Peter ◽  
Justin Graeber ◽  
Sergey Kipriyanov ◽  
Monika Zewe-Welschof ◽  
Marschall S. Runge ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Factor Xa ◽  
Functional Evaluation ◽  
Single Chain ◽  
Single Chain Antibody ◽  
Thrombin Inhibition ◽  
Antibody Fusion Protein

scholarly journals Innovative Three-Step Microwave-Promoted Synthesis of N-Propargyltetrahydroquinoline and 1,2,3-Triazole Derivatives as a Potential Factor Xa (FXa) Inhibitors: Drug Design, Synthesis, and Biological Evaluation

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 491 ◽  
Author(s):  
Fabián Santana-Romo ◽  
Carlos F. Lagos ◽  
Yorley Duarte ◽  
Francisco Castillo ◽  
Yanina Moglie ◽  
...  
Keyword(s):  
Factor Xa ◽  
Biological Evaluation ◽  
Coagulation Cascade ◽  
Chemical Hardness ◽  
Coagulation Parameters ◽  
Triazole Derivatives ◽  
Coronary Syndrome ◽  
Reactivity Indexes ◽  
Potential Factor ◽  
Fxa Inhibitor

The coagulation cascade is the process of the conversion of soluble fibrinogen to insoluble fibrin that terminates in production of a clot. Factor Xa (FXa) is a serine protease involved in the blood coagulation cascade. Moreover, FXa plays a vital role in the enzymatic sequence which ends with the thrombus production. Thrombosis is a common causal pathology for three widespread cardiovascular syndromes: acute coronary syndrome (ACS), venous thromboembolism (VTE), and strokes. In this research a series of N-propargyltetrahydroquinoline and 1,2,3-triazole derivatives as a potential factor Xa (FXa) inhibitor were designed, synthesized, and evaluated for their FXa inhibitor activity, cytotoxicity activity and coagulation parameters. Rational design for the desired novel molecules was performed through protein-ligand complexes selection and ligand clustering. The microwave-assisted synthetic strategy of selected compounds was carried out by using Ullmann-Goldberg, N-propargylation, Mannich addition, Friedel-Crafts, and 1,3-dipolar cycloaddition type reactions under microwave irradiation. The microwave methodology proved to be an efficient way to obtain all novel compounds in high yields (73–93%). Furthermore, a thermochemical analysis, optimization and reactivity indexes such as electronic chemical potential (µ), chemical hardness (η), and electrophilicity (ω) were performed to understand the relationship between the structure and the energetic behavior of all the series. Then, in vitro analysis showed that compounds 27, 29–31, and 34 exhibited inhibitory activity against FXa and the corresponding half maximal inhibitory concentration (IC50) values were calculated. Next, a cell viability assay in HEK293 and HepG2 cell lines, and coagulation parameters (anti FXa, Prothrombin time (PT), activated Partial Thromboplastin Time (aPTT)) of the most active novel molecules were performed to determine the corresponding cytotoxicity and possible action on clotting pathways. The obtained results suggest that compounds 27 and 29 inhibited FXa targeting through coagulation factors in the intrinsic and extrinsic pathways. However, compound 34 may target coagulation FXa mainly by the extrinsic and common pathway. Interestingly, the most active compounds in relation to the inhibition activity against FXa and coagulation parameters did not show toxicity at the performed coagulation assay concentrations. Finally, docking studies confirmed the preferential binding mode of N-propargyltetrahydroquinoline and 1,2,3-triazole derivatives inside the active site of FXa.

Antithrombotic Properties of DU-176b, a Novel, Potent and Orally Active Direct Factor Xa Inhibitor in Rat Models of Arterial and Venous Thrombosis: Comparison with Fondaparinux, an Antithrombin Dependent Factor Xa Inhibitor.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1852-1852 ◽  
Author(s):  
Toshio Fukuda ◽  
Chikako Matsumoto ◽  
Yuko Honda ◽  
Nobutoshi Sugiyama ◽  
Yoshiyuki Morishima ◽  
...  
Keyword(s):  
Venous Thrombosis ◽  
Arterial Thrombosis ◽  
Thrombus Formation ◽  
Dose Range ◽  
Vena Cava ◽  
Factor Xa ◽  
Coagulation Cascade ◽  
Factor Xa Inhibitor ◽  
Rat Models ◽  
Fxa Inhibitor

Abstract Factor Xa (FXa) is an attractive target for the treatment of thrombosis due to its crucial role in the blood coagulation cascade. Fondaparinux, a selective FXa inhibitor, has been approved for clinical use to prevent deep vein thrombosis after orthopedic surgery; however, it requires antithrombin (AT) to exert its antithrombotic effect. It is reported that AT dependent anticoagulants such as heparin are less effective to suppress platelet-rich arterial-type thrombus due to its inaccessibility to thrombus-bound FXa/thrombin. We have developed a potent direct (i.e. AT independent) FXa inhibitor, DU-176b. The objective of this study is to compare the antithrombotic properties of a direct selective FXa inhibitor, DU-176b, with an AT dependent selective FXa inhibitor, fondaparinux. We evaluated the antithrombotic effects of DU-176b and fondaparinux in rat models of arterial and venous thrombosis. The arterial and venous thrombosis was induced by topical application of ferric chloride to the carotid artery and by insertion of a platinum wire into the inferior vena cava, respectively. DU-176b (0.05 – 1.25 mg/kg/h) and fondaparinux (1 – 10 mg/kg/h for arterial thrombosis and 0.03 – 1 mg/kg/h for venous thrombosis) were intravenously administered as continuous infusions. DU-176b prevented both arterial and venous thrombosis in the same dose range. In contrast, the effective doses of fondaparinux markedly differed between these models. A higher dose of fondaparinux more than 100 times was required to inhibit arterial thrombosis compared with venous thrombosis. These results suggest that direct inhibition of FXa is a preferable strategy to AT dependent inhibition for the prevention of thrombus formation in the arteries.

Activated-platelet targeting of CD39 as a potential way forward

2016 ◽  
Vol 36 (01) ◽  
pp. 17-25 ◽  
Author(s):  
J. D. Hohmann ◽  
K. Peter
Keyword(s):  
Recombinant Antibody ◽  
Protein A ◽  
Bleeding Complications ◽  
Nucleoside Triphosphate ◽  
Single Chain ◽  
Single Chain Antibody ◽  
Mortality And Morbidity ◽  
Antiplatelet Effect ◽  
Increased Risk ◽  
Major Interest

SummaryAntiplatelet therapy is given to millions of patients and has saved numerous lives. However, it is also associated with complications including fatal bleedings. Clinically used antiplatelet drugs seem to follow the rule of an inherent link of improved anti-thrombotic potency with increased risk of bleeding complications. Therefore, there is an ongoing quest to develop drugs that are able to break this link that has prevented many patients from receiving antiplatelet protection and has resulted in substantial mortality and morbidity. We describe a new antiplatelet approach that is based on an recombinant antibody protein, a drug format that has recently attracted major interest. Two unique components are genetically combined in this molecule: 1) The ecto-nucleoside triphosphate diphosphohydrolase NTPDase CD39, which enzymatically degrades ATP and ADP to AMP, which is then further degraded to adenosine by the endothelially expressed CD73. Thereby, the platelet activating ADP is reduced and replaced by the platelet inhibiting adenosine resulting in a strong antiplatelet effect. 2) A single-chain antibody (scFv) that specifically binds to the activated GPIIb/IIIa receptor and thus allows targeting to activated platelets. The described fusion protein results in strong enrichment of CD39’s antiplatelet effect, resulting in potent inhibition of platelet adhesion and aggregation and thrombosis in mice. The activated platelet targeting allows using a low systemic concentration that does not interfere with normal haemostasis and thus does not cause bleeding time prolongation in mice. Conclusion: We describe a new antiplatelet approach that promises to deliver strong localized antithrombotic effects without associated bleeding problems.

scholarly journals Tracking yeast pheromone receptor Ste2 endocytosis using fluorogen-activating protein tagging

2018 ◽  
Vol 29 (22) ◽  
pp. 2720-2736 ◽  
Author(s):  
Anita Emmerstorfer-Augustin ◽  
Christoph M. Augustin ◽  
Shadi Shams ◽  
Jeremy Thorner
Keyword(s):  
Integral Membrane Proteins ◽  
Live Cells ◽  
Signal Peptides ◽  
Single Chain ◽  
Single Chain Antibody ◽  
Pheromone Receptor ◽  
New Information ◽  
N Terminus ◽  
A Cell ◽  
Protein Tagging

To observe internalization of the yeast pheromone receptor Ste2 by fluorescence microscopy in live cells in real time, we visualized only those molecules present at the cell surface at the time of agonist engagement (rather than the total cellular pool) by tagging this receptor at its N-terminus with an exocellular fluorogen-activating protein (FAP). A FAP is a single-chain antibody engineered to bind tightly a nonfluorescent, cell-impermeable dye (fluorogen), thereby generating a fluorescent complex. The utility of FAP tagging to study trafficking of integral membrane proteins in yeast, which possesses a cell wall, had not been examined previously. A diverse set of signal peptides and propeptide sequences were explored to maximize expression. Maintenance of the optimal FAP-Ste2 chimera intact required deletion of two, paralogous, glycosylphosphatidylinositol (GPI)-anchored extracellular aspartyl proteases (Yps1 and Mkc7). FAP-Ste2 exhibited a much brighter and distinct plasma membrane signal than Ste2-GFP or Ste2-mCherry yet behaved quite similarly. Using FAP-Ste2, new information was obtained about the mechanism of its internalization, including novel insights about the roles of the cargo-selective endocytic adaptors Ldb19/Art1, Rod1/Art4, and Rog3/Art7.

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