1
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Pruthi RK, Chen D. The Use of Bypassing Treatment Strategies in Hemophilia and Their Effect on Laboratory Testing. Semin Thromb Hemost 2023; 49:651-660. [PMID: 37146647 DOI: 10.1055/s-0043-1768660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Factor VIII and IX inhibitors in congenital hemophilia A and B, respectively, neutralize the infused coagulation factor concentrate rendering them ineffective. Bypassing agents (BPAs) that circumvent the block imposed by the inhibitors are used for the prevention and management of bleeding. Activated prothrombin complex concentrate was the original BPA, recombinant activated factor VII was then introduced, and more recently nonfactor agents that target the procoagulant and anticoagulant systems have been developed and are in clinical use (e.g., emicizumab, a bispecific antibody for hemophilia A). Other BPAs are in clinical trials (e.g., fitusiran targets antithrombin, concizumab and marstacimab target tissue factor pathway inhibitor, and SerpinPC targets activated protein C). The BPAs have a varied effect on coagulation assays, and as more patients are exposed to these agents, it is important to be aware of the effects. Herein, we present an overview of the effect of BPAs on routine and specialized coagulation assays including thrombin generation and viscoelastic assays.
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Affiliation(s)
- Rajiv K Pruthi
- Division of Hematology, Department of Internal Medicine, Comprehensive Hemophilia Center, Rochester, Minnesota
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Special Coagulation Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Dong Chen
- Division of Hematopathology, Department of Laboratory Medicine and Pathology, Special Coagulation Laboratory, Mayo Clinic, Rochester, Minnesota
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2
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Salomon O, Gailani D. A proposal for managing bleeding in patients on therapeutic factor XI(a) inhibitors. J Thromb Haemost 2022; 20:32-38. [PMID: 34735741 PMCID: PMC9540351 DOI: 10.1111/jth.15579] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/27/2021] [Accepted: 11/01/2021] [Indexed: 12/16/2022]
Abstract
Several drugs that reduce functional levels of the plasma protease zymogen factor XI (FXI), or that inhibit its activated form (FXIa), are being evaluated as treatments to prevent thrombosis. Based on the observation that individuals with inherited FXI deficiency have a relatively mild bleeding disorder, it is anticipated that therapeutic FXI(a) inhibitors will have a smaller impact on hemostasis than anticoagulants targeting thrombin or factor Xa. However, even if FXI(a) inhibitors are determined to be safer than currently used anticoagulants, some patients on these drugs will experience abnormal bleeding or require emergent surgery. Strategies for dealing with such situations are required. Treatment with antifibrinolytic agents and low doses of recombinant factor VIIa effectively prevent abnormal bleeding in FXI-deficient patients with alloantibody inhibitors to FXI who undergo surgery. We propose that a similar strategy can be used for patients on therapeutic FXI(a) inhibitors who are bleeding or require invasive procedures.
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Affiliation(s)
- Ophira Salomon
- Thrombosis Unit Sheba Medical Center, Tel Hashomer, Israel
- The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - David Gailani
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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3
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Bar-Ilan A, Livnat T, Hoffmann M, Binder L, Zakar M, Guy R, Felikman Y, Moschcovich L, Shenkman B, Monroe D, Hershkovitz O, Kenet G, Hart G. In vitro characterization of MOD-5014, a novel long-acting carboxy-terminal peptide (CTP)-modified activated FVII. Haemophilia 2018. [DOI: 10.1111/hae.13428] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - T. Livnat
- Sackler Medical School; Tel Aviv University; Tel Aviv Israel
- National Hemophilia Center; Sheba Medical Center; Tel Hashomer, Ramat Gan Israel
| | | | | | - M. Zakar
- OPKO Biologics; Kiryat Gat Israel
| | - R. Guy
- OPKO Biologics; Kiryat Gat Israel
| | | | | | - B. Shenkman
- Sackler Medical School; Tel Aviv University; Tel Aviv Israel
- National Hemophilia Center; Sheba Medical Center; Tel Hashomer, Ramat Gan Israel
| | - D. Monroe
- University of North Carolina; NC USA
| | | | - G. Kenet
- Sackler Medical School; Tel Aviv University; Tel Aviv Israel
- National Hemophilia Center; Sheba Medical Center; Tel Hashomer, Ramat Gan Israel
| | - G. Hart
- OPKO Biologics; Kiryat Gat Israel
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4
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David T, Kim YC, Ely LK, Rondon I, Gao H, O'Brien P, Bolt MW, Coyle AJ, Garcia JL, Flounders EA, Mikita T, Coughlin SR. Factor XIa-specific IgG and a reversal agent to probe factor XI function in thrombosis and hemostasis. Sci Transl Med 2017; 8:353ra112. [PMID: 27559095 DOI: 10.1126/scitranslmed.aaf4331] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 07/11/2016] [Indexed: 11/02/2022]
Abstract
Thrombosis is a major cause of morbidity and mortality. Current antithrombotic drugs are not ideal in that they must balance prevention of thrombosis against bleeding risk. Inhibition of coagulation factor XI (FXI) may offer an improvement over existing antithrombotic strategies by preventing some forms of thrombosis with lower bleeding risk. To permit exploration of this hypothesis in humans, we generated and characterized a series of human immunoglobulin Gs (IgGs) that blocked FXIa active-site function but did not bind FXI zymogen or other coagulation proteases. The most potent of these IgGs, C24 and DEF, inhibited clotting in whole human blood and prevented FeCl3-induced carotid artery occlusion in FXI-deficient mice reconstituted with human FXI and in thread-induced venous thrombosis in rabbits at clinically relevant doses. At doses substantially higher than those required for inhibition of intravascular thrombus formation in these models, DEF did not increase cuticle bleeding in rabbits or cause spontaneous bleeding in macaques over a 2-week study. Anticipating the desirability of a reversal agent, we also generated a human IgG that rapidly reversed DEF activity ex vivo in human plasma and in vivo in rabbits. Thus, an active site-directed FXIa-specific antibody can block thrombosis in animal models and, together with the reversal agent, may facilitate exploration of the roles of FXIa in human disease.
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Affiliation(s)
- Tovo David
- Cardiovascular Research Institute, University of California, San Francisco, Room SC452P, 555 Mission Bay Boulevard South, San Francisco, CA 94143-3122, USA
| | - Yun Cheol Kim
- Centers for Therapeutic Innovation San Francisco, Pfizer Inc., 1700 Owens Street, San Francisco, CA 94158, USA
| | - Lauren K Ely
- Centers for Therapeutic Innovation San Francisco, Pfizer Inc., 1700 Owens Street, San Francisco, CA 94158, USA
| | - Isaac Rondon
- Centers for Therapeutic Innovation San Francisco, Pfizer Inc., 1700 Owens Street, San Francisco, CA 94158, USA
| | - Huilan Gao
- Centers for Therapeutic Innovation Boston, Pfizer Inc., 18th Floor, 3 Blackfan Circle, Boston, MA 02115, USA
| | - Peter O'Brien
- Pharmacokinetics, Dynamics, and Metabolism Biotherapeutics and Translational Research, Pfizer Inc., 10724 Science Center Drive, San Diego, CA 92121, USA
| | - Michael W Bolt
- Drug Safety Research and Development, Pfizer Inc., 1 Burtt Road, Andover, MA 01810, USA
| | - Anthony J Coyle
- Centers for Therapeutic Innovation Boston, Pfizer Inc., 18th Floor, 3 Blackfan Circle, Boston, MA 02115, USA
| | - Jorge L Garcia
- PMI Preclinical, 1031 Bing Street, San Carlos, CA 94070, USA
| | | | - Thomas Mikita
- Centers for Therapeutic Innovation San Francisco, Pfizer Inc., 1700 Owens Street, San Francisco, CA 94158, USA.
| | - Shaun R Coughlin
- Cardiovascular Research Institute, University of California, San Francisco, Room SC452P, 555 Mission Bay Boulevard South, San Francisco, CA 94143-3122, USA.
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Zivelin A, Rima D, Livnat T, Martinowitz U, Kenet G. A highly sensitive thrombin generation assay for assessment of recombinant activated factor VII therapy in haemophilia patients with an inhibitor. Thromb Haemost 2017; 105:688-95. [DOI: 10.1160/th10-08-0542] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2010] [Accepted: 12/17/2010] [Indexed: 11/05/2022]
Abstract
SummaryBypass agents are the common treatment for haemophilia patients who develop inhibitory antibodies. Laboratory assessment of the efficacy of bypassing agent therapy is a challenge. In the present work we modified the conditions triggering thrombin generation (TG) assay in order to find the most sensitive assay for detection of rFVIIa and its analogue NN1731 in haemophilic plasma. TG was measured in samples of normal plasma, plasma of haemophilia patient with inhibitors, as well as haemophilia induced plasma. Recalcification-induced TG was compared to tissue factor (TF) -induced TG in the presence and absence of rFVIIa and NN1731. Recalcification-induced TG (without TF) in haemophilic plasma yielded baseline flat curves, with increased TG as a consequence of spiking the plasma rFVIIa. Using our system, we observed both dose-dependence and time-dependence of rFVIIa effect on TG. Elevated concentrations of TF mask the difference between rFVIIa-treated and non-treated haemophilic plasma. NN1731 yielded normal-isation of recalcification-induced TG curves (without TF) which may reflect high potency. In conclusion, we suggest that triggering TG by recalcification-only may be the most sensitive assay for determining the impact of bypassing agents in haemophilic plasma, and may serve as a caution surrogate safety marker in future studies.
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Microparticles variability in fresh frozen plasma: preparation protocol and storage time effects. BLOOD TRANSFUSION = TRASFUSIONE DEL SANGUE 2016; 14:228-37. [PMID: 27136430 DOI: 10.2450/2016.0179-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 10/20/2015] [Indexed: 12/26/2022]
Abstract
BACKGROUND Extracellular vesicles or microparticles exhibiting procoagulant and thrombogenic activity may contribute to the haemostatic potential of fresh frozen plasma. MATERIALS AND METHODS Fresh frozen plasma was prepared from platelet-rich plasma at 20 °C (Group-1 donors) or directly from whole blood at 4 °C (Group-2 donors). Each unit was aseptically divided into three parts, stored frozen for specific periods of time, and analysed by flow cytometry for procoagulant activity immediately after thaw or following post-thaw storage for 24 h at 4 °C. Donors' haematologic, biochemical and life-style profiles as well as circulating microparticles were analysed in parallel. RESULTS Circulating microparticles exhibited a considerable interdonor but not intergroup variation. Fresh frozen plasma units were enriched in microparticles compared to plasma in vivo. Duration of storage significantly affected platelet- and red cell-derived microparticles. Fresh frozen plasma prepared directly from whole blood contained more residual platelets and more platelet-derived microparticles compared to fresh frozen plasma prepared from platelet-rich plasma. Consequently, there was a statistically significant difference in total, platelet- and red cell-derived microparticles between the two preparation protocols over storage time in the freezer. Preservation of the thawed units for 24 h at 4 °C did not significantly alter microparticle accumulation. Microparticle accumulation and anti-oxidant capacity of fresh frozen plasma was positively or negatively correlated, respectively, with the level of circulating microparticles in individual donors. DISCUSSION The preparation protocol and the duration of storage in the freezer, independently and in combination, influenced the accumulation of microparticles in fresh frozen plasma units. In contrast, storage of thawed units for 24 h at 4 °C had no significant effect on the concentration of microparticles.
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7
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The impact of thrombin generation and rotation thromboelastometry on assessment of severity of factor XI deficiency. Thromb Res 2015; 136:465-73. [DOI: 10.1016/j.thromres.2015.06.025] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 04/28/2015] [Accepted: 06/17/2015] [Indexed: 11/22/2022]
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8
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Brinkman HJM. Global assays and the management of oral anticoagulation. Thromb J 2015; 13:9. [PMID: 25762867 PMCID: PMC4355453 DOI: 10.1186/s12959-015-0037-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 01/12/2015] [Indexed: 12/12/2022] Open
Abstract
Coagulation tests range from global or overall tests to assays specific to individual clotting factors and their inhibitors. Whether a particular test is influenced by an oral anticoagulant depends on the principle of the test and the type of oral anticoagulant. Knowledge on coagulation tests applicable in monitoring status and reversal of oral anticoagulation is a prerequisite when studying potential reversal agents or when managing anticoagulation in a clinical setting. Specialty tests based on the measurement of residual activated factor X (Xa) or thrombin activity, e.g., are highly effective for determining the concentration of the new generation direct factor Xa- and thrombin inhibitors, but these tests are unsuitable for the assessment of anticoagulation reversal by non-specific prohemostatic agents like prothrombin complex concentrate (PCC) and recombinant factor VIIa (FVIIa). Global coagulation assays, in this respect, seem more appropriate. This review evaluates the current status on the applicability of the global coagulation assays PT, APTT, thrombin generation and thromboelastography in the management of oral anticoagulation by vitamin K antagonists and the direct factor Xa and thrombin inhibitors. Although all global tests are influenced by both types of anticoagulants, not all tests are useful for monitoring anticoagulation and reversal thereof. Many (pre)analytical conditions are of influence on the assay readout, including the oral anticoagulant itself, the concentration of assay reagents and the presence of other elements like platelets and blood cells. Assay standardization, therefore, remains an issue of importance.
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Affiliation(s)
- Herm Jan M Brinkman
- Department of Plasma Proteins, Sanquin Research, Plesmanlaan 125, 1066 CX Amsterdam, The Netherlands
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9
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Livnat T, Martinowitz U, Azar-Avivi S, Zivelin A, Brutman-Barazani T, Lubetsky A, Kenet G. Combined administration of FVIII and rFVIIa improves haemostasis in haemophilia A patients with high-responding inhibitors - a thrombin generation-guided pilot study. Haemophilia 2013; 19:782-9. [DOI: 10.1111/hae.12181] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2013] [Indexed: 11/29/2022]
Affiliation(s)
- T. Livnat
- The Israeli National Hemophilia Center and Thrombosis Unit; Sheba Medical Center, Tel Hashomer and Sackler School of Medicine, Tel Aviv University; Tel Hashomer; Israel
| | - U. Martinowitz
- The Israeli National Hemophilia Center and Thrombosis Unit; Sheba Medical Center, Tel Hashomer and Sackler School of Medicine, Tel Aviv University; Tel Hashomer; Israel
| | - S. Azar-Avivi
- The Israeli National Hemophilia Center and Thrombosis Unit; Sheba Medical Center, Tel Hashomer and Sackler School of Medicine, Tel Aviv University; Tel Hashomer; Israel
| | - A. Zivelin
- The Israeli National Hemophilia Center and Thrombosis Unit; Sheba Medical Center, Tel Hashomer and Sackler School of Medicine, Tel Aviv University; Tel Hashomer; Israel
| | - T. Brutman-Barazani
- The Israeli National Hemophilia Center and Thrombosis Unit; Sheba Medical Center, Tel Hashomer and Sackler School of Medicine, Tel Aviv University; Tel Hashomer; Israel
| | - A. Lubetsky
- The Israeli National Hemophilia Center and Thrombosis Unit; Sheba Medical Center, Tel Hashomer and Sackler School of Medicine, Tel Aviv University; Tel Hashomer; Israel
| | - G. Kenet
- The Israeli National Hemophilia Center and Thrombosis Unit; Sheba Medical Center, Tel Hashomer and Sackler School of Medicine, Tel Aviv University; Tel Hashomer; Israel
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10
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Livnat T, Shenkman B, Spectre G, Tamarin I, Dardik R, Israeli A, Rivkind A, Shabtai M, Marinowitz U, Salomon O. Recombinant factor VIIa treatment for asymptomatic factor VII deficient patients going through major surgery. Blood Coagul Fibrinolysis 2013; 23:379-87. [PMID: 22527290 DOI: 10.1097/mbc.0b013e328352e8e2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Factor VII deficiency is the most common among the rare autosomal recessive coagulation disorders worldwide. In factor VII deficient patients, the severity and clinical manifestations cannot be reliably determined by factor VII levels. Severe bleeding tends to occur in individuals with factor VII activity levels of 2% or less of normal. Patients with 2-10% factor VII vary between asymptomatic to severe life threatening haemorrhages behaviour. Recombinant factor VIIa (rFVIIa) is the most common replacement therapy for congenital factor VII deficiency. However, unlike haemophilia patients for whom treatment protocols are straight forward, in asymptomatic factor VII deficiency patients it is still debatable. In this study, we demonstrate that a single and very low dose of recombinant factor VIIa enabled asymptomatic patients with factor VII deficiency to go through major surgery safely. This suggestion was also supported by thrombin generation, as well as by thromboelastometry.
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Affiliation(s)
- Tami Livnat
- Sheba Medical Center, Institute of Thrombosis and Haemostasis, Tel Hashomer, Israel
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11
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Ay Y, Balkan C, Karapinar DY, Akin M, Bilenoğlu B, Kavakli K. Feasibility of Using Thrombin Generation Assay (TGA) for Monitoring Bypassing Agent Therapy in Patients With Hemophilia Having Inhibitors. Clin Appl Thromb Hemost 2012; 19:389-94. [DOI: 10.1177/1076029612438611] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Background: Monitoring bypassing agent therapy and observing concordance with clinical hemostasis is crucial in vital hemorrhages and major surgeries in patients with hemophilia having inhibitor. Objective: We aimed to investigate the value of the thrombin generation assay (TGA) and thromboelastography (TEG) for monitoring hemostasis in patients with hemophilia having inhibitor, during supplementation therapy with bypassing agents. Patients and Methods: The study group consisted of 7 patients with hemophilia having factor VIII inhibitor. All patients were male. The median age of the participants was 10 years. Age range was 6 to 32 years. The median inhibitor level was 10 Bethesda units (BU), with a range of 5 to 32 BU. A total of 17 bleeding episodes were evaluated. Both TEG and TGA tests were assessed in addition to clinical responses. Assessments were made prior to bypass agent therapy such as recombinant factor VIIa (rFVIIa) or activated prothrombin complex concentrate (aPCC) for bleeding episodes, during the first hour and 24 hours after either intervention in patients. Results: No relation between clinical response and TGA or TEG parameters was found in patients. There was no difference between clinical responses after rFVIIa and aPCC treatments. However, after aPCC treatment, endogenous thrombin potential and peak thrombin levels and also TEG R, K, and alpha angle degrees were significantly higher. Conclusions: In conclusion, we found that the clinical effectiveness of bypass therapy in hemophilia cannot be assessed by TGA and TEG.
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Affiliation(s)
- Yilmaz Ay
- Department of Hematology, Ege University Medical School, Children’s Hospital, Ege Hemophilia Center, Bornova, Izmir, Turkey
| | - Can Balkan
- Department of Hematology, Ege University Medical School, Children’s Hospital, Ege Hemophilia Center, Bornova, Izmir, Turkey
| | - Deniz Yilmaz Karapinar
- Department of Hematology, Ege University Medical School, Children’s Hospital, Ege Hemophilia Center, Bornova, Izmir, Turkey
| | - Mehmet Akin
- Department of Hematology, Ege University Medical School, Children’s Hospital, Ege Hemophilia Center, Bornova, Izmir, Turkey
| | - Basri Bilenoğlu
- Department of Hematology, Ege University Medical School, Children’s Hospital, Ege Hemophilia Center, Bornova, Izmir, Turkey
| | - Kaan Kavakli
- Department of Hematology, Ege University Medical School, Children’s Hospital, Ege Hemophilia Center, Bornova, Izmir, Turkey
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Severe factor X deficiency in three unrelated Palestinian patients is caused by homozygosity for the mutation c302delG-correlation with thrombin generation and thromboelastometry. Blood Coagul Fibrinolysis 2011; 22:673-9. [DOI: 10.1097/mbc.0b013e32834ad785] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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13
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Gray LD, Hussey MA, Larson BM, Machlus KR, Campbell RA, Koch G, Ezban M, Hedner U, Wolberg AS. Recombinant factor VIIa analog NN1731 (V158D/E296V/M298Q-FVIIa) enhances fibrin formation, structure and stability in lipidated hemophilic plasma. Thromb Res 2011; 128:570-6. [PMID: 21561645 PMCID: PMC3156970 DOI: 10.1016/j.thromres.2011.04.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 03/22/2011] [Accepted: 04/13/2011] [Indexed: 11/25/2022]
Abstract
INTRODUCTION The bypassing agent recombinant factor VIIa (rFVIIa) is efficacious in treating bleeding in hemophilia patients with inhibitors. Efforts have focused on the rational engineering of rFVIIa variants with increased hemostatic potential. One rFVIIa analog (V158D/E296V/M298Q-FVIIa, NN1731) improves thrombin generation and clotting in purified systems, whole blood from hemophilic patients and factor VIII-deficient mice. METHODS We used calibrated automated thrombography and plasma clotting assays to compare effects of bypassing agents (rFVIIa, NN1731) on hemophilic clot formation, structure, and ability to resist fibrinolysis. RESULTS Both rFVIIa and NN1731 shortened the clotting onset and increased the maximum rate of fibrin formation and fibrin network density in hemophilic plasma clots. In the presence of tissue plasminogen activator, both rFVIIa and NN1731 shortened the time to peak turbidity (TTPeak(tPA)) and increased the area under the clot formation curve (AUC(tPA)). Phospholipids increased both rFVIIa and NN1731 activity in a lipid concentration-dependent manner. Estimated geometric mean concentrations of rFVIIa and NN1731 producing similar onset, rate, TTPeak(tPA), and AUC(tPA) as seen with 100% factors VIII and IX were: 24.5, 74.3, 29.7, and 37.1 nM rFVIIa, and 8.6, 31.2, 9.0, and 11.3 nM NN1731, respectively. In each case, the NN1731 concentration was significantly lower than rFVIIa. CONCLUSIONS These findings suggest that like rFVIIa, NN1731 improves the formation, structure, and stability of hemophilic clots. Higher lipid concentrations may facilitate assessment of both rFVIIa and NN1731 activity. NN1731 appears likely to support rapid clot formation in tissues with high endogenous fibrinolytic activity.
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Affiliation(s)
- Laura D. Gray
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Michael A. Hussey
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Brittany M. Larson
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kellie R. Machlus
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Robert A. Campbell
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Gary Koch
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mirella Ezban
- Novo Nordisk A/S, Novo Nordisk Park, Maaloev, Denmark
| | - Ulla Hedner
- Novo Nordisk A/S, Novo Nordisk Park, Maaloev, Denmark
| | - Alisa S. Wolberg
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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Mitrophanov AY, Reifman J. Kinetic modeling sheds light on the mode of action of recombinant factor VIIa on thrombin generation. Thromb Res 2011; 128:381-90. [DOI: 10.1016/j.thromres.2011.05.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 05/05/2011] [Accepted: 05/10/2011] [Indexed: 11/29/2022]
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15
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Ollivier V, Wang J, Manly D, Machlus KR, Wolberg AS, Jandrot-Perrus M, Mackman N. Detection of endogenous tissue factor levels in plasma using the calibrated automated thrombogram assay. Thromb Res 2010; 125:90-6. [PMID: 19345399 PMCID: PMC2826585 DOI: 10.1016/j.thromres.2009.03.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 03/09/2009] [Accepted: 03/12/2009] [Indexed: 11/22/2022]
Abstract
BACKGROUND The calibrated automated thrombogram (CAT) assay measures thrombin generation in plasma. OBJECTIVE Use the CAT assay to detect endogenous tissue factor (TF) in recalcified platelet-rich plasma (PRP) and platelet-free plasma (PFP). METHODS Blood from healthy volunteers was collected into citrate and incubated at 37 degrees C with or without lipopolysaccharide (LPS) for 5 hours. PRP and PFP were prepared and clotting was initiated by recalcification. Thrombin generation was measured using the CAT assay. RESULTS The lag time (LT) was significantly shortened in PRP prepared from LPS-treated blood compared with untreated blood (10+/-3 min versus 20+/-6 min), and this change was reversed by the addition of inactivated human factor VIIa. LPS stimulation did not change the peak thrombin. Similar results were observed in PFP (21+/-4 min versus 35+/-5 min). LPS stimulation also significantly reduced the LT of PRP and PFP derived from blood containing citrate and a factor XIIa inhibitor. Finally, a low concentration of exogenous TF shortened the LT of PFP prepared from unstimulated, citrated blood without affecting the peak thrombin. CONCLUSION Changes in LT in the CAT assay can be used to monitor levels of endogenous TF in citrated plasma.
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Affiliation(s)
- Veronique Ollivier
- Inserm, U698, Paris, F-75018 France; Université Paris 7, Paris, F-75018 France
| | - Jianguo Wang
- Division of Hematology/Oncology Department of Medicine University of North Carolina at Chapel Hill Chapel Hill, North Carolina, USA
| | - David Manly
- Division of Hematology/Oncology Department of Medicine University of North Carolina at Chapel Hill Chapel Hill, North Carolina, USA
| | - Kellie R. Machlus
- Department of Pathology University of North Carolina at Chapel Hill Chapel Hill, North Carolina, USA
| | - Alisa S. Wolberg
- Department of Pathology University of North Carolina at Chapel Hill Chapel Hill, North Carolina, USA
| | | | - Nigel Mackman
- Division of Hematology/Oncology Department of Medicine University of North Carolina at Chapel Hill Chapel Hill, North Carolina, USA
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Prothrombin complex concentrate (Beriplex P/N) for control of bleeding after kidney trauma in a rabbit dilutional coagulopathy model. Thromb Res 2009; 125:272-7. [PMID: 19913880 DOI: 10.1016/j.thromres.2009.10.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 10/19/2009] [Accepted: 10/21/2009] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Fluid resuscitation after trauma often results in dilutional coagulopathy that may hinder control of bleeding and, once initial hemostasis has been secured, heighten risk of perioperative bleeding when further surgery is required. Since multiple coagulation factor deficiencies typically accompany fluid resuscitation, prothrombin complex concentrate (PCC) containing factors II, VII, IX and X may potentially offer greater hemostatic efficacy than coagulation factor monotherapy. MATERIALS AND METHODS Anesthetized normothermic rabbits were hemodiluted 50-60% by phased blood withdrawal and infusion of hydroxyethyl starch and erythrocytes. The animals were randomly assigned to receive saline placebo, 25 IU x kg(-1) PCC (Beriplex P/N) or 180 microg x kg(-1) activated recombinant factor VII (rFVIIa; NovoSeven). Immediately thereafter, bleeding was precipitated by a standardized kidney incision. RESULTS PCC accelerated hemostasis compared both with saline and rFVIIa (p=0.002 for both comparisons). The median times to hemostasis in the PCC, saline and rFVIIa groups were 12, 19 and 28 min, respectively. PCC reduced blood loss by a median of 43 mL with a 95% confidence interval (CI) of 8.0-67.5 mL vs. saline and 82 mL (CI, 35.0-110.0 mL) vs. rFVIIa. PCC augmented peak thrombin generation by a median of 104.1 nM (CI, 78.3-142.3 nM) compared with saline and 105.8 nM (CI, 70.7-139.5 nM ) relative to rFVIIa. At the respective 180 microg x kg(-1) and 25 IU x kg(-1) doses tested, rFVIIa displayed thrombogenicity in the Wessler stasis model, while PCC did not. CONCLUSIONS In an animal model of dilutional coagulopathy and kidney trauma, PCC accelerated hemostasis and diminished blood loss compared with rFVIIa monotherapy.
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Thrombin generation assay as a possible tool for assessment of reduced activity of clotting factors induced by antiphospholipid antibodies and in-vitro evaluation of treatment options. Blood Coagul Fibrinolysis 2009; 20:661-6. [PMID: 19730246 DOI: 10.1097/mbc.0b013e32832ff595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Bleeding is a rare manifestation of antiphospholipid syndrome, unless associated with reduced clotting factors or severe thrombocytopenia. Accurate assessment of the autoantibodies in plasma is very important since the autoantibodies can lead to bleeding or thrombosis. The objective of the present study was to define the inhibitors causing reduced clotting activity in a patient with antiphospholipids antibodies and to assess the potential of thrombin generation assay to assist in establishment of optimal treatment in case of major bleeding. Levels of clotting factors as well as inhibitors to factors II, V, VII, VIII, IX, X and XI were defined. For detection of inhibitors to prothrombin crossed immunoelectrophoresis was used. IgG was purified by commercial protein A column. Thrombin generation was measured using a fluorometric assay in platelet-poor and platelet-rich plasma. Inhibitors toward the activity of factors V, VII, VIII, IX, X and XI were defined and also an inhibitor to prothrombin antigen. No thrombin generation was induced in the patient's plasma by recalcification even in the presence of recombinant factor VIIa or factor VIII inhibitor bypassing activity. In contrast, addition of platelets from either donor or patient or synthetic phospholipids normalized the thrombin generation. The thrombin generation model showed that the addition of platelets and no recombinant factor VIIa or factor VIII inhibitor bypassing activity would correct thrombin generation in vitro. On this basis, platelet concentrates were administered to a patient with bleeding caused by lupus anticoagulant and low clotting factors activity.
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KENET G, LUBETSKY A, LUBOSHITZ J, RAVID B, TAMARIN I, VARON D, MARTINOWITZ U. Lower doses of rFVIIa therapy are safe and effective for surgical interventions in patients with severe FXI deficiency and inhibitors. Haemophilia 2009; 15:1065-73. [DOI: 10.1111/j.1365-2516.2009.02043.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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MARTINOWITZ U, LIVNAT T, ZIVELIN A, KENET G. Concomitant infusion of low doses of rFVIIa and FEIBA in haemophilia patients with inhibitors. Haemophilia 2009; 15:904-10. [DOI: 10.1111/j.1365-2516.2009.02028.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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Trappenburg MC, van Schilfgaarde M, Marchetti M, Spronk HM, ten Cate H, Leyte A, Terpstra WE, Falanga A. Elevated procoagulant microparticles expressing endothelial and platelet markers in essential thrombocythemia. Haematologica 2009; 94:911-8. [PMID: 19508974 DOI: 10.3324/haematol.13774] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Most cell types, including blood--and vascular cells, produce microparticles upon activation. Since cellular microparticles are known to be elevated in thromboembolic diseases, we hypothesized a role for microparticles in the pathogenesis of thrombosis in essential thrombocythemia. DESIGN AND METHODS In plasma samples from 21 patients with essential thrombocythemia and ten healthy subjects, the levels and the cellular origin of microparticles were determined by flowcytometric analysis, while the microparticle-associated procoagulant activity was measured using a thrombin generation assay. RESULTS Patients with essential thrombocythemia had significantly higher numbers of circulating annexin V-positive microparticles than controls (median 4500 vs. 2500x10(6) events/L; p=0.039), including significantly higher numbers of microparticles positive for the platelet marker CD61 (p=0.043), the endothelial markers CD62E (p=0.009) and CD144 (p=0.021), and for tissue factor (p=0.036). CD62E was co-expressed with the platelet marker CD41 on microparticles, suggesting a bilineage origin of such microparticles, which were observed only in patients with risk factors for thrombosis. Patients with essential thrombocythemia had higher plasma levels of mature von Willebrand factor (p=0.045) but similar propeptide levels compared to controls. In thrombin generation analyses, microparticle-rich plasma from patients with essential thrombocythemia had a shorter lag time (p=0.001) and higher peak height (p=0.038) than plasma from controls. Peak height correlated significantly with the total number of microparticles (R=0.634, p<0.001). CONCLUSIONS Patients with essential thrombocythemia had higher number of circulating microparticles with platelet and endothelial markers, suggesting ongoing platelet and endothelial activation. This was confirmed by an increased level of mature von Willebrand factor, an abnormal mature von Willebrand factor/propeptide ratio, and a hypercoagulable state reflected in thrombin generation. These findings suggest a role for microparticles in thrombosis in essential thrombocythemia.
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Affiliation(s)
- Marijke C Trappenburg
- Department of Internal Medicine, Onze Lieve Vrouwe Gasthuis, Amsterdam, The Netherlands
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Abstract
Abstract
The management of factor XI deficiency is not straightforward for three reasons: firstly, the role of this factor in the coagulation pathway is not clearly understood; secondly, the bleeding tendency, although mild, is unpredictable and does not clearly relate to the factor XI level; and thirdly, all treatment products, although available, have some potentially serious side effects. These factors (or enigmas) contribute to the variable management of patients with this coagulation factor deficiency, but recent research is helping to clarify some of these areas.
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Mechanisms of action of recombinant activated factor VII in the context of tissue factor concentration and distribution. Blood Coagul Fibrinolysis 2008; 19:743-55. [DOI: 10.1097/mbc.0b013e3283104093] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Salomon O, Katz BZ, Dardik R, Livnat T, Steinberg DM, Achiron R, Seligsohn U. Plasma levels of microparticles at 24 weeks of gestation do not predict subsequent pregnancy complications. Fertil Steril 2008; 92:682-7. [PMID: 18692836 DOI: 10.1016/j.fertnstert.2008.06.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2008] [Revised: 06/11/2008] [Accepted: 06/11/2008] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To discern whether plasma levels of microparticles (MPs) measured at 24 weeks of gestation predict late complications of pregnancy. DESIGN Secondary analysis of samples obtained prospectively. SETTING Large academic medical center. PATIENT(S) Two hundred sixty-two healthy women selected from 642 nulliparous women with singleton pregnancies. INTERVENTION(S) Sampling for blood cell MPs and thrombophilias at 24 weeks of gestation and measurements of blood flow resistance in uterine, placental, and umbilical arteries at 24 and 31 to 33 weeks of gestation. MAIN OUTCOME MEASURE(S) Relationship between levels of MPs and late pregnancy complications, thrombophilias, and blood flow resistance. RESULT(S) Flow cytometry only detected MPs derived from endothelial cells (CD31(+)) and platelet (CD41(+)). No statistically significant correlation was found between levels of CD31(+) or CD41(+) MPs and subsequent occurrence of pregnancy-induced hypertension, preeclampsia, intrauterine growth restriction, or small for gestational age infants. Nor was there a statistically significant correlation with blood flow resistance parameters at 24 weeks of gestation (except for the left uterine artery) or at 31 to 33 weeks of gestation. Levels of these MPs in thrombophilic and nonthrombophilic women were similar. CONCLUSION(S) Levels of circulating MPs at 24 weeks of gestation had no predictive value for subsequent development of pregnancy-induced hypertension, preeclampsia, intrauterine growth restriction, or small for gestational age infants.
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Affiliation(s)
- Ophira Salomon
- Amalia Biron Research Institute of Thrombosis and Hemostasis, Sheba Medical Center, Tel Hashomer and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
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LIVNAT T, MARTINOWITZ U, ZIVELIN A, SELIGSOHN U. Effects of factor VIII inhibitor bypassing activity (FEIBA), recombinant factor VIIa or both on thrombin generation in normal and haemophilia A plasma. Haemophilia 2008; 14:782-6. [DOI: 10.1111/j.1365-2516.2008.01688.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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van Veen JJ, Gatt A, Makris M. Thrombin generation testing in routine clinical practice: are we there yet? Br J Haematol 2008; 142:889-903. [PMID: 18564356 DOI: 10.1111/j.1365-2141.2008.07267.x] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Thrombin is the central enzyme in the coagulation cascade. Estimation of an individual's potential to generate thrombin may correlate more closely with a hyper- or hypo-coagulable phenotype, compared to traditional coagulation tests. The possible correlation and recent technical advances in thrombin generation measurement has caused a significant interest in the method and the development of commercial assays. Several variations of the assay exist depending on the defect to be investigated. Fluorogenic thrombin generation assays have acceptable intra-laboratory variation but a higher inter-laboratory variation. Variation in preanalytical variables makes comparisons between studies difficult. Thrombin generation is highly variable between individuals and there are suggestions that this may allow individualized treatment based on global haemostatic response in patients with bleeding disorders or on anticoagulant therapy. In patients with thrombotic disorders it may be possible to identify those at higher risk of recurrent thrombosis. For both scenarios, however, data from large prospective studies are lacking or inconclusive and a good relationship between thrombin generation and phenotype remains to be established. Further standardization of the assay is needed before large multicentre studies can be conducted and until then thrombin generation in routine clinical practice is not yet a reality.
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Affiliation(s)
- J J van Veen
- Leicester Haemophilia Comprehensive Care Centre & Haemostasis and Thrombosis Unit, Leicester, UK.
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Campbell RA, Fischer TH, Wolberg AS. A novel approach to improving recombinant factor VIIa activity with a preserved platelet preparation. Br J Haematol 2007; 138:82-93. [PMID: 17555451 DOI: 10.1111/j.1365-2141.2007.06617.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Recombinant activated factor VII (NovoSeven, rFVIIa) is used to abrogate bleeding in haemophiliacs with inhibitors and is hypothesised to work by increasing activated factor X generation on the platelet surface. We hypothesised that rFVIIa activity could be increased by the co-addition of platelet procoagulant surface. This study characterised the ability of a rehydrated, lyophilised (RL) platelet preparation to increase rFVIIa activity in haemophilic conditions. RL platelets supported thrombin generation in the presence of factors VIII and IX but, in the absence of factors VIII and IX, thrombin generation was significantly reduced. RL platelets supported rFVIIa-mediated thrombin generation in a rFVIIa-concentration dependent manner. In a cell-based in vitro model of haemophilia, the presence of RL platelets increased the rFVIIa-dependent thrombin generation rate 2.8-fold compared with rFVIIa alone. Similarly, the addition of RL platelets plus rFVIIa to the in vitro model of haemophilia and to haemophilic platelet-rich plasma shortened the onset of clot formation and increased clot stability in a fibrinolytic environment versus rFVIIa alone. These results suggest that RL platelets can support rFVIIa-mediated thrombin generation, and that co-administration of RL platelets with rFVIIa may increase the efficacy of rFVIIa in some patients.
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Affiliation(s)
- Robert A Campbell
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599-7525, USA
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Affiliation(s)
- K Hoots
- M. D. Anderson Cancer Center and University of Texas Health Science Center, Gulf States Hemophilia and Thrombophilia Center, Houston, TX 77030, USA.
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Abstract
The appropriate development of hemostasis encompasses a delicate equilibrium between anti- and prothrombotic forces developing during three distinct phases (primary hemostasis, coagulation and fibrinolysis) that are closely linked to each other and precisely regulated to close vessel wounds, promote vascular healing and maintain vessel patency. Imbalance in each of these systems produces either hemorrhagic or thrombotic disorders. Inherited bleeding disorders, caused by quantitative or qualitative alterations of either platelets or plasma proteins involved in blood coagulation and fibrinolysis, may lead to serious and lifelong bleeding conditions, the severity of which is inversely associated with the degree of the underlying defect. Rapid and reliable identification of these pathologies is worthy of focus to allow the adoption of appropriate substitutive or supportive antihemorrhagic therapies. Evaluation of the hemorrhage-prone patient requires careful recording of the medical history, attention to pertinent physical findings and the discretionary use of laboratory resources. Owing to the low diagnostic efficiency of clinical history and examination, an appropriate and reliable laboratory approach, encompassing first- and second-line testing, is essential to screen, diagnose and monitor patients with bleeding diatheses. As both the analytical sensitivity and responsiveness of traditional coagulation assays to different abnormalities differ widely, each laboratory should establish individual guidelines based on field experience and on reagent and instrument characteristics. Emerging evidence indicates that the implementation of global coagulation tests, such as the thrombin generation assay and clot waveform analysis, would provide additional information for clinical decision-making for patients with inherited bleeding disorders.
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Affiliation(s)
- Giuseppe Lippi
- Sezione di Chimica e Microscopia Clinica, Dipartimento di Scienze Morfologico-Biomediche, Università degli Studi di Verona, Verona, Italy.
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Mathew P, Simon TL, Hunt KE, Crookston KP. How we manage requests for recombinant factor VIIa (NovoSeven). Transfusion 2007; 47:8-14. [PMID: 17207224 DOI: 10.1111/j.1537-2995.2007.01058.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Prasad Mathew
- Department of Pathology, University of New Mexico, New Mexico, USA
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Abstract
Bypassing agents consist of activated prothrombin complex concentrates (aPCC) and recombinant factor VIIa (rFVIIa). Their main utilization is for prevention and treatment of bleeding complications, which may occur in inhibitor-developing haemophiliacs, although new indications for rFVIIa (e.g. trauma-related and cerebral bleeds) are now under evaluation in clinical trials. The mechanisms of action for these agents are still not fully understood. The relative complexity of the composition of aPCC suggests the possibility of multiple modes of action for achieving haemostasis. Among those possibilities, the contributions of activated factor X and prothrombin have been demonstrated in recent years both in vitro and in animal models for the only aPCC which remains on the market. rFVIIa also exhibits a complex mode of action, improving coagulation through both tissue factor-dependent and -independent pathways. The various mechanisms that occur at the cellular surfaces, particularly on the outer leaflet of the platelet membrane, primarily contribute to Xase complex formation and thrombin generation. The ways in which these agents affect the complex kinetics of fibrin formation at the site of vascular damage need further clarification, although significant progress has been achieved in the last 10 years. In addition, the ex vivo monitoring that would reflect achievement of haemostasis in vivo is still not standardized, although several attempts using thromboelastography, thrombin generation and the kinetics of fibrin formation have been initiated.
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Affiliation(s)
- C Negrier
- Unité d'Hémostase Clinique, Centre Régional de Traitement de l'Hémophilie, Lyon, France.
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Hoots WK. Challenges in the Therapeutic Use of a “So-Called” Universal Hemostatic Agent: Recombinant Factor VIIa. Hematology 2006:426-31. [PMID: 17124094 DOI: 10.1182/asheducation-2006.1.426] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Abstract
Recombinant factor VIIa (rFVIIa) was developed in the early 1990s to provide “bypassing” hemostatic therapy for hemophilia A and B patients with inhibitors. More recently, it has been licensed for use in patients with inherited deficiency of factor VII. Since it was licensed for use in hemophilia with inhibitors in the US, Europe, and other countries for these specific indications, it has been used selectively but in a wide array of clinical settings for uncontrolled hemorrhage in individuals without an inherited bleeding disorder. Many of these uses have been described in the medical literature as case reports or small, uncontrolled series. Several randomized clinical trials (RCT) for these “off-label” medical uses have been published in recent months and will serve as the focus of this review. In particular, a review of an RCT for spontaneous intracranial hemorrhage that has demonstrated clinical efficacy in reducing both mortality and volume of central nervous system hemorrhage will be offered. A brief discussion of hypothesized physiologic mechanisms of supraphysiologic doses of rFVIIa will introduce the clinical discussion of these broad off-label uses. Since rFVIIa is a very expensive therapy, possible strategies for optimizing its use in the these settings will be presented.
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Affiliation(s)
- W Keith Hoots
- M.D. Anderson Cancer Center and University of Texas Health Science Center, Gulf States Hemophilia and Thrombophilia Center, 6655 Travis St., Suite 400, Houston TX 77030, USA.
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