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Dagher MC, Ersayin A, Seyve L, Castellan M, Moreau C, Choisnard L, Thielens N, Marlu R, Polack B, Thomas A. Toward non-factor therapy in hemophilia: an antithrombin insensitive Gla-domainless factor Xa as tissue factor pathway inhibitor bait. Res Pract Thromb Haemost 2023; 7:102175. [PMID: 37841511 PMCID: PMC10568284 DOI: 10.1016/j.rpth.2023.102175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 07/24/2023] [Accepted: 08/06/2023] [Indexed: 10/17/2023] Open
Abstract
Background Gla-domainless factor (F) Xa (GD-FXa) was proposed as a trap to endogenous anticoagulant tissue factor pathway inhibitor (TFPI) to restore thrombin generation in hemophilia. Using computational chemistry and experimental approaches, we previously showed that S195A GD-FXa also binds TFPI and restores ex vivo coagulation in plasma obtained from person(s) with hemophilia. Methods To design a GD-FXa variant with improved anti-TFPI affinity, we performed molecular dynamics simulations and identified suitable sites for mutagenesis. The calculations identified residues R150FXa and K96Fxa as cold-spots of interaction between GD-FXa and the K2 domain of TFPI. In the three-dimensional model, both residues face toward TFPI hydrophobic residues and are thus potential candidates for mutagenesis into hydrophobic residues to favor an improved protein-protein interaction. Results Catalytically inactive GD-FXa variants containing the S195A mutation and the additional mutations K96Y, R150I, R150G, R150F, and K96YR150F, were produced to experimentally confirm these computational hypotheses. Among these mutants, the R150FFXa and the K96YR150FFXa were slightly more effective than S195A GD-FXa in restoring coagulation in FVIII deficient plasmas. However, in surface plasmon resonance experiments, they showed TFPI binding affinities in the same range and acted similarly as S195A GD-FXa in FXa/TFPI competition assays. In contrast, the R150 mutants completely lost their interactions with antithrombin as observed in the surface plasmon resonance experiments. Conclusions We therefore conclude that their antithrombin resistance is responsible for their improved thrombin generation, through an extension of their half-lives.
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Affiliation(s)
- Marie-Claire Dagher
- Univ. Grenoble Alpes, UMR5525, CNRS, TIMC, Grenoble, France
- Univ. Grenoble Alpes, UMR5075, CEA, CNRS, IBS, Grenoble, France
| | - Atanur Ersayin
- Univ. Grenoble Alpes, UMR5525, CNRS, TIMC, Grenoble, France
| | - Landry Seyve
- Haemostasis Unit, Hematology Laboratory, University Grenoble Hospital, Grenoble Alpes University, Grenoble, France
| | | | - Cyril Moreau
- Univ. Grenoble Alpes, UMR5525, CNRS, TIMC, Grenoble, France
| | - Luc Choisnard
- Univ. Grenoble Alpes, UMR5063, ICMG FR 2607, CNRS, Département de Pharmacochimie Moléculaire, Grenoble, France
| | - Nicole Thielens
- Univ. Grenoble Alpes, UMR5075, CEA, CNRS, IBS, Grenoble, France
| | - Raphaël Marlu
- Univ. Grenoble Alpes, UMR5525, CNRS, TIMC, Grenoble, France
- Haemostasis Unit, Hematology Laboratory, University Grenoble Hospital, Grenoble Alpes University, Grenoble, France
| | - Benoît Polack
- Univ. Grenoble Alpes, UMR5525, CNRS, TIMC, Grenoble, France
| | - Aline Thomas
- Univ. Grenoble Alpes, UMR5063, ICMG FR 2607, CNRS, Département de Pharmacochimie Moléculaire, Grenoble, France
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2
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Reitsma SE, Holle LA, Bouck EG, Monroe DM, Mast AE, Burthem J, Bolton-Maggs PHB, Gidley GN, Wolberg AS. Tissue factor pathway inhibitor is a potential modifier of bleeding risk in factor XI deficiency. J Thromb Haemost 2023; 21:467-479. [PMID: 36696199 PMCID: PMC10111213 DOI: 10.1016/j.jtha.2022.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/26/2022] [Accepted: 10/06/2022] [Indexed: 01/26/2023]
Abstract
BACKGROUND Factor (F) XI deficiency is associated with increased bleeding risk in some individuals. Neither FXI levels nor clinical clotting assays predict the bleeding risk. Compared with controls, FXI-deficient bleeders have reduced clot formation, decreased fibrin network density, and increased susceptibility to fibrinolysis. Tissue factor pathway inhibitor (TFPI) was recently implicated as a modifying factor in individuals with bleeding of unknown cause. OBJECTIVES To determine the potential of TFPI in modifying the bleeding risk in FXI-deficient individuals. METHODS The effects of TFPI on thrombin generation and clot formation, structure, and fibrinolysis in FXI-deficient plasma were measured in vitro in the absence or presence of inhibitory anti-TFPI antibody or exogenous recombinant TFPIα. Total plasma TFPI concentration was measured in 2 independent cohorts of controls and FXI-deficient individuals classified as bleeders or nonbleeders (cohort 1: 10 controls and 16 FXI-deficient individuals; cohort 2: 48 controls and 57 FXI-deficient individuals) and correlated with ex vivo plasma clot formation and fibrinolysis parameters associated with bleeding risk. RESULTS In an in vitro FXI deficiency model, inhibition of TFPI enhanced thrombin generation and clot formation, increased the network density, and decreased fibrinolysis, whereas an increase in TFPI had the opposite effects. Compared with controls, plasma from FXI-deficient bleeders had higher TFPI concentration. Total plasma TFPI concentrations correlated with parameters from ex vivo clotting and fibrinolysis assays that differentiate FXI-deficient bleeders and nonbleeders. CONCLUSION Coagulation and fibrinolysis parameters that differentiate FXI-deficient nonbleeders and bleeders were altered by plasma TFPIα. Total plasma TFPI was increased in FXI-deficient bleeders. TFPI may modify the bleeding risk in FXI-deficient individuals.
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Affiliation(s)
- Stéphanie E Reitsma
- Department of Pathology and Laboratory Medicine and UNC Blood Research Center, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Lori A Holle
- Department of Pathology and Laboratory Medicine and UNC Blood Research Center, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Emma G Bouck
- Department of Pathology and Laboratory Medicine and UNC Blood Research Center, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Dougald M Monroe
- Department of Medicine and UNC Blood Research Center, University of North Carolina at Chapel Hill, North Carolina, USA
| | - Alan E Mast
- Versiti Blood Research Institute, Milwaukee, Wisconsin, USA
| | - John Burthem
- Department of Haematology, Manchester Royal Infirmary, Manchester University NHS Foundation Trust, Manchester, UK; Institute of Cancer Sciences, The University of Manchester, Manchester, UK
| | | | - Gillian N Gidley
- Institute of Cancer Sciences, The University of Manchester, Manchester, UK; Department of Haematology, St James' Hospital, Leeds Teaching Hospitals Trust, UK
| | - Alisa S Wolberg
- Department of Pathology and Laboratory Medicine and UNC Blood Research Center, University of North Carolina, Chapel Hill, North Carolina, USA.
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3
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Rodríguez-Merchán EC, De Pablo-Moreno JA, Liras A. Gene Therapy in Hemophilia: Recent Advances. Int J Mol Sci 2021; 22:ijms22147647. [PMID: 34299267 PMCID: PMC8306493 DOI: 10.3390/ijms22147647] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/14/2021] [Accepted: 07/15/2021] [Indexed: 02/07/2023] Open
Abstract
Hemophilia is a monogenic mutational disease affecting coagulation factor VIII or factor IX genes. The palliative treatment of choice is based on the use of safe and effective recombinant clotting factors. Advanced therapies will be curative, ensuring stable and durable concentrations of the defective circulating factor. Results have so far been encouraging in terms of levels and times of expression using mainly adeno-associated vectors. However, these therapies are associated with immunogenicity and hepatotoxicity. Optimizing the vector serotypes and the transgene (variants) will boost clotting efficacy, thus increasing the viability of these protocols. It is essential that both physicians and patients be informed about the potential benefits and risks of the new therapies, and a register of gene therapy patients be kept with information of the efficacy and long-term adverse events associated with the treatments administered. In the context of hemophilia, gene therapy may result in (particularly indirect) cost savings and in a more equitable allocation of treatments. In the case of hemophilia A, further research is needed into how to effectively package the large factor VIII gene into the vector; and in the case of hemophilia B, the priority should be to optimize both the vector serotype, reducing its immunogenicity and hepatotoxicity, and the transgene, boosting its clotting efficacy so as to minimize the amount of vector administered and decrease the incidence of adverse events without compromising the efficacy of the protein expressed.
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Affiliation(s)
- E. Carlos Rodríguez-Merchán
- Osteoarticular Surgery Research, Hospital La Paz Institute for Health Research–IdiPAZ (La Paz University Hospital—Autonomous University of Madrid), 28046 Madrid, Spain;
| | - Juan Andres De Pablo-Moreno
- Department of Genetic, Physiology and Microbiology, Biology School, Complutense University of Madrid, 28040 Madrid, Spain;
| | - Antonio Liras
- Department of Genetic, Physiology and Microbiology, Biology School, Complutense University of Madrid, 28040 Madrid, Spain;
- Correspondence:
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Tomeo F, Mariz S, Brunetta AL, Stoyanova-Beninska V, Penttila K, Magrelli A. Haemophilia, state of the art and new therapeutic opportunities, a regulatory perspective. Br J Clin Pharmacol 2021; 87:4183-4196. [PMID: 33772837 PMCID: PMC8596702 DOI: 10.1111/bcp.14838] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 03/04/2021] [Accepted: 03/16/2021] [Indexed: 12/13/2022] Open
Abstract
Haemophilia A and B are rare bleeding disorders. Over the past decades, they have been transformed from debilitating diseases to manageable conditions in the Western world. However, optimizing haemophilia care remains challenging in developing countries. Several challenges and unmet needs remain in the treatment of the haemophilia limiting the QoL of patients. These challenges are now being addressed by extended half‐life recombinant factors, rebalancing and substitution therapies. Gene therapy and genome editing show promise for a definite clinical cure. Here, we provide an overview of new therapeutic opportunities for haemophilia and their advances and limitations from a regulatory perspective. The database on human medicines from the European Medicines Agency (EMA) was used and data from rare disease (orphan) designations and EPARs were retrieved for the analysis. Clinical trial databases were used to query all active studies on haemophilia. Gene therapy medicinal products based on AAV and lentiviral vectors are in development and clinical trials have reported substantial success in ameliorating bleeding tendency in haemophilia patients. The prospect of gene editing for correction of the underlying mutation is on the horizon and has considerable potential. With regard to the benefit of the gene therapy medicinal products, more long‐term efficacy and safety data are awaited. We are entering an era of innovation and abundance in treatment options for those affected by bleeding disorders, but issues remain about the affordability and accessibility to patients.
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Affiliation(s)
| | - Segundo Mariz
- Orphan Office, European Medicines Agency, Amsterdam, The Netherlands
| | - Angelo Loris Brunetta
- Italian Foundation 'L.Giambrone' for the cure of Thalassemia, Castel Volturno, Italy
| | | | | | - Armando Magrelli
- National Center for Drug Research and Evaluation, Istituto Superiore di Sanità, Rome, Italy
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5
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Darwish NHE, Godugu K, Mousa SA. Sulfated non-anticoagulant low molecular weight heparin in the prevention of cancer and non-cancer associated thrombosis without compromising hemostasis. Thromb Res 2021; 200:109-114. [PMID: 33582600 DOI: 10.1016/j.thromres.2021.01.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 01/13/2021] [Accepted: 01/16/2021] [Indexed: 11/17/2022]
Abstract
INTRODUCTION Cancer-associated thrombosis (CAT) accounts for about 20% of all cases of Venous Thromboembolism (VTE). Tissue factor (TF) is documented to be highly expressed on cancer cells and pathological angiogenic endothelial cells. Here, we used a novel oxidized sulfated ultra-LMWH, S-NACH, which is devoid of anti-factor Xa and IIa activities with limited to no systemic anticoagulant effects. This sulfated form has enhanced binding to vascular endothelial cells (EC) and releases and potentiates the action of tissue factor pathway inhibitor (TFPI). S-NACH binds with high affinity to EC, releases and binds to EC TFPI, and promotes vascular antithrombotic effect with limited to no risk of bleeding complications. MATERIALS AND METHODS We investigated the effects of S-NACH on clot kinetics in vitro and in vivo. Also, we investigated the effects of S-NACH on CAT mediated by human acute leukemia cells (K562) and human pancreatic cancer cells (SUIT2). RESULTS S-NACH was associated with ~3-fold increase of TFPI 2 levels within 3 h. Also, S-NACH reversed the hypercoagulability state that is associated with cancer cells in vitro. In vivo, S-NACH at 20 mg/kg subcutaneously (SC) had no effect on bleeding time compared to both tinzaparin and enoxaparin at 5 mg/kg SC. S-NACH did not show any anti-IIa or anti-Xa activities in comparison to tinzaparin and enoxaparin (p < 0.001). CONCLUSION Data suggest the importance of S-NACH through its EC binding, EC TFPI release and its interaction with TFPI in enhancing its activity in the prevention of cancer and non-cancer associated thrombosis with limited to no bleeding complications.
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Affiliation(s)
- Noureldien H E Darwish
- Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, Rensselaer, NY, USA; Hematology Unit, Clinical Pathology Department, Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Kavitha Godugu
- Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, Rensselaer, NY, USA
| | - Shaker A Mousa
- Pharmaceutical Research Institute, Albany College of Pharmacy and Health Sciences, Rensselaer, NY, USA.
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6
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A bispecific antibody demonstrates limited measurability in routine coagulation assays. Blood Coagul Fibrinolysis 2020; 31:353-365. [PMID: 32467424 DOI: 10.1097/mbc.0000000000000921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
: Accurate monitoring of coagulation, needed for optimal management of patients with haemophilia A with inhibitors, presents a challenge for treating physicians. Although global haemostatic assays may be used in this population, their utility with nonfactor therapies has yet to be established in the clinical setting. The aim of this study was to assess options for potential haemostatic activity monitoring and feasibility for factor VIII (FVIII)-equivalency measurement with a sequence identical analogue (SIA) to emicizumab using different coagulation assays. SIA was analysed using five commercial chromogenic assays and activated partial thromboplastin time (aPTT) assays including clot waveform analysis using five different triggers. Recombinant FVIII served as a comparator in all assays. Thrombin generation in haemophilia A plasma was measured using extrinsic and intrinsic trigger conditions (tissue factor or Factor XIa). Of the five chromogenic assays, a concentration-dependent increase in Factor Xa was observed with one assay, with human Factor IXa and X reagents. The SIA dose-response signal plateaued at therapeutically relevant concentrations and was nonparallel with FVIII reference, thereby not permitting FVIII-equivalence assessment. aPTT varied between reagents, with aPTT normalization occurring at low and below-therapeutic SIA concentrations. SIA [600 nmol/l (90 μg/ml)] only partially restored thrombin generation in individual haemophilia A patient plasma. FVIII-equivalence of SIA could not be determined using standard FVIII protocols and was found to be highly influenced by assay type, analytical conditions and parameters used for calculation. New and/or modified methodology and standard reagents specific for use with nonfactor therapies are required for their utilization in the clinical setting.
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7
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Maintaining extraembryonic expression allows generation of mice with severe tissue factor pathway inhibitor deficiency. Blood Adv 2020; 3:489-498. [PMID: 30755437 DOI: 10.1182/bloodadvances.2018018853] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 12/28/2018] [Indexed: 11/20/2022] Open
Abstract
Tissue factor pathway inhibitor (TFPI) is a serine protease with multiple anticoagulant activities. The Kunitz1 (K1) domain of TFPI binds the active site of factor VIIa and is required for inhibition of tissue factor (TF)/factor VIIa catalytic activity. Mice lacking TFPI K1 domain die in utero. TFPI is highly expressed on trophoblast cells of the placenta. We used genetic strategies to selectively ablate exon 4 encoding TFPI K1 domain in the embryo, while maintaining expression in trophoblast cells. This approach resulted in expected Mendelian frequency of TFPI K1 domain-deficient mice. Real-time polymerase chain reaction confirmed 95% to 99% genetic deletion and a similar reduction in transcript expression. Western blotting confirmed the presence of a truncated protein instead of full-length TFPI. Mice with severe TFPI K1 deficiency exhibited elevated thrombin-antithrombin (TAT) levels, frequent fibrin deposition in renal medulla, and increased susceptibility to TF-induced pulmonary embolism. They were fertile, and most lived normal life spans without any overt thrombotic events. Of 43 mice observed, 2 displayed extensive brain ischemia and infarction. We conclude that in contrast to complete absence of TFPI K1 domain, severe deficiency is compatible with in utero development, adult survival, and reproductive functions in mice. Inhibition of TFPI activity is being evaluated as a means of boosting thrombin generation in hemophilia patients. Our results show that in mice severe reduction of TFPI K1 activity is associated with a prothrombotic state without overt developmental outcomes. We note fibrin deposits in the kidney and rare cases of brain ischemia.
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8
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Franchini M, Marano G, Pati I, Veropalumbo E, Vaglio S, Pupella S, Masiello F, Cruciani M, Mengoli C, Liumbruno GM. Investigational drugs to treat hemophilia. Expert Opin Investig Drugs 2020; 29:295-301. [DOI: 10.1080/13543784.2020.1722999] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Massimo Franchini
- Italian National Blood Centre, National Institute of Health, Rome, Italy
- Department of Hematology and Transfusion Medicine, Carlo Poma Hospital, Mantua, Italy
| | - Giuseppe Marano
- Italian National Blood Centre, National Institute of Health, Rome, Italy
| | - Ilaria Pati
- Italian National Blood Centre, National Institute of Health, Rome, Italy
| | - Eva Veropalumbo
- Italian National Blood Centre, National Institute of Health, Rome, Italy
| | - Stefania Vaglio
- Italian National Blood Centre, National Institute of Health, Rome, Italy
| | - Simonetta Pupella
- Italian National Blood Centre, National Institute of Health, Rome, Italy
| | - Francesca Masiello
- Italian National Blood Centre, National Institute of Health, Rome, Italy
| | - Mario Cruciani
- Italian National Blood Centre, National Institute of Health, Rome, Italy
- Infection Control Committee and Antibiotic Stewardship Programme, AULSS9 Scaligera, Verona, Italy
| | - Carlo Mengoli
- Italian National Blood Centre, National Institute of Health, Rome, Italy
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9
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Prophylactic treatment in hemophilic patients with inhibitors. Blood Coagul Fibrinolysis 2019; 30:S14-S18. [DOI: 10.1097/mbc.0000000000000823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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NMR structure determination of Ixolaris and factor X(a) interaction reveals a noncanonical mechanism of Kunitz inhibition. Blood 2019; 134:699-708. [PMID: 31133602 DOI: 10.1182/blood.2018889493] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 05/05/2019] [Indexed: 11/20/2022] Open
Abstract
Ixolaris is a potent tick salivary anticoagulant that binds coagulation factor Xa (FXa) and zymogen FX, with formation of a quaternary tissue factor (TF)/FVIIa/ FX(a)/Ixolaris inhibitory complex. Ixolaris blocks TF-induced coagulation and PAR2 signaling and prevents thrombosis, tumor growth, and immune activation. We present a high-resolution structure and dynamics of Ixolaris and describe the structural basis for recognition of FX. Ixolaris consists of 2 Kunitz domains (K1 and K2) in which K2 is strikingly dynamic and encompasses several residues involved in FX binding. This indicates that the backbone plasticity of K2 is critical for Ixolaris biological activity. Notably, a nuclear magnetic resonance-derived model reveals a mechanism for an electrostatically guided, high-affinity interaction between Ixolaris and FX heparin-binding (pro)exosite, resulting in an allosteric switch in the catalytic site. This is the first report revealing the structure-function relationship of an anticoagulant targeting a zymogen serving as a scaffold for TF inhibition.
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11
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New therapies using nonfactor products for patients with hemophilia and inhibitors. Blood 2019; 133:399-406. [DOI: 10.1182/blood-2018-07-820712] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 09/28/2018] [Indexed: 12/18/2022] Open
Abstract
Abstract
Regular prophylaxis with factor VIII (FVIII) or FIX products to prevent bleeding in patients with severe hemophilia A (HA) and HB, respectively, results in marked suppression of the onset of arthropathy and contributes greatly to improvements in quality of life. Some issues remain with the use of clotting factor replacement therapy, however. The need for multiple IV infusions is associated with a substantial mental and physical burden, and the hemostatic effect of bypassing agents (BPAs) in patients with inhibitor is inconsistent. The development of subcutaneous products with prolonged hemostatic efficiency, irrespective of the presence of inhibitors, has been a longtime wish for patients. A new class of therapeutic agents that act by enhancing coagulation (emicizumab) and inhibiting anticoagulant pathways (fitusiran and concizumab) have been established, and clinical trials using these nonfactor products are ongoing. The current findings have demonstrated that prophylaxis by nonfactor products supports marked reductions of bleeding episodes in hemophilia patients with or without inhibitor. Emicizumab has already been approved for use internationally. Some concerns are evident, however. Thrombotic microangiopathy and thromboembolism have occurred in 5 emicizumab-treated patients receiving repeated infusions of activated prothrombin complex concentrates, and a sinus vein thrombosis has occurred in a fitusiran-treated patient receiving repeated infusions of FVIII product. Moreover, reliable techniques to monitor hemostatic function in patients receiving nonfactor products with concomitant BPA or FVIII/FIX therapies require further assessment. These novel therapeutic agents have promising hemostatic properties, although wider experience in hemophilia centers is warranted to establish appropriate therapeutic strategies.
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12
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Cohen I, Coban M, Shahar A, Sankaran B, Hockla A, Lacham S, Caulfield TR, Radisky ES, Papo N. Disulfide engineering of human Kunitz-type serine protease inhibitors enhances proteolytic stability and target affinity toward mesotrypsin. J Biol Chem 2019; 294:5105-5120. [PMID: 30700553 DOI: 10.1074/jbc.ra118.007292] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 01/27/2019] [Indexed: 12/30/2022] Open
Abstract
Serine protease inhibitors of the Kunitz-bovine pancreatic trypsin inhibitor (BPTI) family are ubiquitous biological regulators of proteolysis. These small proteins are resistant to proteolysis, but can be slowly cleaved within the protease-binding loop by target proteases, thereby compromising their activity. For the human protease mesotrypsin, this cleavage is especially rapid. Here, we aimed to stabilize the Kunitz domain structure against proteolysis through disulfide engineering. Substitution within the Kunitz inhibitor domain of the amyloid precursor protein (APPI) that incorporated a new disulfide bond between residues 17 and 34 reduced proteolysis by mesotrypsin 74-fold. Similar disulfide engineering of tissue factor pathway inhibitor-1 Kunitz domain 1 (KD1TFPI1) and bikunin Kunitz domain 2 (KD2bikunin) likewise stabilized these inhibitors against mesotrypsin proteolysis 17- and 6.6-fold, respectively. Crystal structures of disulfide-engineered APPI and KD1TFPI1 variants in a complex with mesotrypsin at 1.5 and 2.0 Å resolution, respectively, confirmed the formation of well-ordered disulfide bonds positioned to stabilize the binding loop. Long all-atom molecular dynamics simulations of disulfide-engineered Kunitz domains and their complexes with mesotrypsin revealed conformational stabilization of the primed side of the inhibitor-binding loop by the engineered disulfide, along with global suppression of conformational dynamics in the Kunitz domain. Our findings suggest that the Cys-17-Cys-34 disulfide slows proteolysis by dampening conformational fluctuations in the binding loop and minimizing motion at the enzyme-inhibitor interface. The generalizable approach developed here for the stabilization against proteolysis of Kunitz domains, which can serve as important scaffolds for therapeutics, may thus find applications in drug development.
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Affiliation(s)
- Itay Cohen
- From the Avram and Stella Goldstein-Goren Department of Biotechnology Engineering and the National Institute of Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Matt Coban
- the Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, Jacksonville, Florida 32224
| | - Anat Shahar
- the National Institute for Biotechnology in the Negev (NIBN), Beer-Sheva 84105, Israel
| | - Banumathi Sankaran
- the Molecular Biophysics and Integrated Bioimaging Division, Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and
| | - Alexandra Hockla
- the Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, Jacksonville, Florida 32224
| | - Shiran Lacham
- From the Avram and Stella Goldstein-Goren Department of Biotechnology Engineering and the National Institute of Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Thomas R Caulfield
- the Department of Neuroscience, Mayo Clinic College of Medicine, Jacksonville, Florida 32224
| | - Evette S Radisky
- the Department of Cancer Biology, Mayo Clinic Comprehensive Cancer Center, Jacksonville, Florida 32224,
| | - Niv Papo
- From the Avram and Stella Goldstein-Goren Department of Biotechnology Engineering and the National Institute of Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel,
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Abstract
Hemophilia A (HA) and hemophilia B (HB) are the most common severe bleeding disorders. Replacement therapy, providing the missing coagulation factor, has been the mainstay of treatment both prophylactically and to treat bleeding. Despite widespread availability of safe and effective replacement therapy, patients with HA and HB continue to experience a tremendous burden of treatment, breakthrough bleeding, and progressive joint disease, as well as high rates of inhibitor development. These remaining challenges are now being addressed by incredible advances in bioengineering. Recombinant bioengineering has led to replacement therapies with easier modes of administration, decreased immunogenicity, increased efficacy, and extended half-lives. Emicizumab, a bispecific antibody that acts as a substitutive therapy for HA, has been approved for patients with and without inhibitors. Novel compounds are in development to exploit the natural balance of hemostasis by targeting the natural anticoagulants protein C, protein S, tissue factor pathway inhibitor, and antithrombin. The substitution and rebalancing therapies provide an opportunity for steady-state hemostatic control without exposure to immunogenic clotting factor proteins. As such, they may have broader applications outside those being investigated in the clinical trial programs.
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14
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Post-transcriptional, post-translational and pharmacological regulation of tissue factor pathway inhibitor. Blood Coagul Fibrinolysis 2018; 29:668-682. [PMID: 30439766 DOI: 10.1097/mbc.0000000000000775] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
: Tissue factor (TF) pathway inhibitor (TFPI) is an endogenous natural anticoagulant that readily inhibits the extrinsic coagulation initiation complex (TF-FVIIa-Xa) and prothrombinase (FXa, FVa and calcium ions). Alternatively, spliced TFPI isoforms (α, β and δ) are expressed by vascular and extravascular cells and regulate thrombosis and haemostasis, as well as cell signalling functions of TF complexes via protease-activated receptors (PARs). Proteolysis of TFPI plays an important role in regulating physiological roles of the TF pathway in host defense and possibly haemostasis. Elimination of TFPI inhibition has therefore been proposed as an approach to improve haemostasis in haemophilia patients. In this review, we focus on posttranscription and translational modification of TFPI and its function in thrombosis and how pharmacological inhibitors and endogenous proteases interfere with TFPI and alter haemostasis.
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15
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Girard TJ, Grunz K, Lasky NM, Malone JP, Broze GJ. Re-evaluation of mouse tissue factor pathway inhibitor and comparison of mouse and human tissue factor pathway inhibitor physiology. J Thromb Haemost 2018; 16:2246-2257. [PMID: 30194803 PMCID: PMC6235150 DOI: 10.1111/jth.14288] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Indexed: 11/30/2022]
Abstract
Essentials Mouse models are often used to define roles of tissue factor pathway inhibitor (TFPI) in man. TFPI isoform-specific KOs reveal unexpected differences between mouse and human TFPI physiology. Mouse plasma contains 20 times more TFPI than man, derived from TFPIγ, a form not found in man. TFPIγ null mice, expressing only TFPI isoforms α and β, may better reflect the human situation. SUMMARY: Background Mouse models can provide insight into the pathophysiology of human thrombosis and hemostasis. Tissue factor pathway inhibitor (TFPI) regulates coagulation through protein S (PS)-enhanced factor (F) Xa inhibition and FXa-dependent inhibition of FVIIa/tissue factor (TF) activity. TFPI is expressed as isoforms α and β in man, and α, β and γ in the mouse. Objective Assess the reliability of extending TFPI-related studies in mice to humans. Method Compare mouse and human TFPI physiology using a variety of methods. Results Mouse TFPI and human TFPI are similar in regard to: (i) the mechanisms for FVIIa/TF and FXa inhibition; (ii) TFPIα is a soluble form and TFPIβ is glycosyl phosphatidyl inositol (GPI) membrane anchored; (iii) the predominant circulating form of TFPI in plasma is lipoprotein-associated; (iv) low levels of TFPIα circulate in plasma and increase following heparin treatment; and (v) TFPIα is the isoform in platelets. They differ in that: (i) mouse TFPI circulates at a ~20-fold higher concentration; (ii) mouse lines with isolated isoform deletions show this circulating mouse TFPI is derived from TFPIγ; (iii) sequences homologous to the mouse TFPIγ exon are present in many species, including man, but in primates are unfavorable for splicing; and (iv) tandem mass spectrometry (MS/MS) detects sequences for TFPI isoforms α and β in human plasma and α and γ in mouse plasma. Conclusion To dissect the pathophysiological roles of human TFPIα and TFPIβ, studies in TFPIγ null mice, expressing only α and β, only α or only β should better reflect the human situation.
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Affiliation(s)
- Thomas J. Girard
- Division of Hematology, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Kristin Grunz
- Division of Hematology, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Nina M. Lasky
- Division of Hematology, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - James P. Malone
- Proteomics Core Laboratory, Institute of Clinical and Translational Sciences, Washington University School of Medicine, St. Louis, MO
| | - George J. Broze
- Division of Hematology, Department of Medicine, Washington University School of Medicine, St. Louis, MO
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16
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Belyanko TI, Gursky YG, Dobrynina NI, Orlova AV, Rutkevich NM, Savochkina LP, Skamrov AV, Skrypina NA, Bibilashvilli RS. A Study of the Structure of Trypsin-Like Serine Proteinases: 1. Study of Mini-Plasminogen Activation Using Tryptophan Fluorescence. Biophysics (Nagoya-shi) 2018. [DOI: 10.1134/s0006350918050032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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17
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Novel therapeutics for hemophilia and other bleeding disorders. Blood 2018; 132:23-30. [DOI: 10.1182/blood-2017-09-743385] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 04/17/2018] [Indexed: 11/20/2022] Open
Abstract
Abstract
Hemophilia and von Willebrand disease are the most common congenital bleeding disorders. Treatment of these disorders has focused on replacement of the missing coagulation factor to prevent or treat bleeding. New technologies and insights into hemostasis have driven the development of many promising new therapies for hemophilia and von Willebrand disease. Emerging bypass agents including zymogen-like factor IXa and Xa molecules are in development and a bispecific antibody, emicizumab, demonstrated efficacy in a phase 3 trial in people with hemophilia A and inhibitors. Tissue factor pathway inhibitor, the protein C/S system, and antithrombin are targets of novel compounds in development to alter the hemostatic balance and new approaches using modified factor VIII molecules are being tested for prevention and eradication of inhibitor antibodies in hemophilia A. The first recombinant von Willebrand factor (VWF) product has been approved and has unique VWF multimer content and does not contain factor VIII. These new approaches may offer better routes of administration, improved dosing regimens, and better efficacy for prevention and treatment of bleeding in congenital bleeding disorders.
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18
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DeRosa JR, Moyer BS, Lumen E, Wolfe AJ, Sleeper MB, Bianchi AH, Crawford A, McGuigan C, Wortel D, Fisher C, Moody KJ, Blanden AR. RPtag as an Orally Bioavailable, Hyperstable Epitope Tag and Generalizable Protein Binding Scaffold. Biochemistry 2018; 57:3036-3049. [PMID: 29722979 DOI: 10.1021/acs.biochem.8b00170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Antibodies are the most prolific biologics in research and clinical environments because of their ability to bind targets with high affinity and specificity. However, antibodies also carry liabilities. A significant portion of the life-science reproducibility crisis is driven by inconsistent performance of research-grade antibodies, and clinical antibodies are often unstable and require costly cold-chain management to reach their destinations in active form. In biotechnology, antibodies are also limited by difficulty integrating them in many recombinant systems due to their size and structural complexity. A switch to small, stable, sequence-verified binding scaffolds may overcome these barriers. Here we present such a scaffold, RPtag, based on a ribose-binding protein (RBP) from extremophile Caldanaerobacter subterraneus. RPtag binds an optimized peptide with pM affinity, is stable to extreme temperature, pH, and protease treatment, readily refolds after denaturation, is effective in common laboratory applications, was rationally engineered to bind bioactive PDGF-β, and was formulated as a gut-stable orally bioavailable preparation.
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Affiliation(s)
- Jennifer R DeRosa
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
| | - Brandon S Moyer
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
| | - Ellie Lumen
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
| | - Aaron J Wolfe
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
| | - Meegan B Sleeper
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
| | - Anthony H Bianchi
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
| | - Ashleigh Crawford
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
| | - Connor McGuigan
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
| | - Danique Wortel
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
| | - Cheyanne Fisher
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
| | - Kelsey J Moody
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
| | - Adam R Blanden
- Ichor Therapeutics, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States.,RecombiPure, Inc. , 2521 US-11 , Lafayette , New York 13084 , United States
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19
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Augustsson C, Svensson A, Kjaer B, Chao TY, Wenjuan X, Krogh BO, Breinholt J, Clausen JT, Hilden I, Petersen HH, Petersen LC. Factor Xa and VIIa inhibition by tissue factor pathway inhibitor is prevented by a monoclonal antibody to its Kunitz-1 domain. J Thromb Haemost 2018; 16:893-904. [PMID: 29532595 DOI: 10.1111/jth.14000] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Indexed: 12/24/2022]
Abstract
Essentials Activated FVII (FVIIa) and FX (FXa) are inhibited by tissue factor pathway inhibitor (TFPI). A monoclonal antibody, mAb2F22, was raised against the N-terminal fragment of TFPI (1-79). mAb2F22 bound exclusively to the K1 domain of TFPI (KD ∼1 nm) and not to the K2 domain. mAb2F22 interfered with inhibition of both FVIIa and FXa activities and restored clot formation. SUMMARY Background Initiation of coagulation is induced by binding of activated factor VII (FVIIa) to tissue factor (TF) and activation of factor X (FX) in a process regulated by tissue factor pathway inhibitor (TFPI). TFPI contains three Kunitz-type protease inhibitor domains (K1-K3), of which K1 and K2 block the active sites of FVIIa and FXa, respectively. Objective To produce a monoclonal antibody (mAb) directed towards K1, to characterize the binding epitope, and to study its effect on TFPI inhibition. Methods A monoclonal antibody, mAb2F22, was raised against the N-terminal TFPI(1-79) fragment. Binding data were obtained by surface plasmon resonance analysis. The Fab-fragment of mAb2F22, Fab2F22, was expressed and the structure of its complex with TFPI(1-79) determined by X-ray crystallography. Effects of mAb2F22 on TFPI inhibition were measured in buffer- and plasma-based systems. Results mAb2F22 bound exclusively to K1 of TFPI (KD ~1 nm) and not to K2. The crystal structure of Fab2F22/TFPI (1-79) mapped an epitope on K1 including seven residues upstream of the domain. TFPI inhibition of TF/FVIIa amidolytic activity was neutralized by mAb2F22, although the binding epitope on K1 did not include the P1 residue. Binding of mAb2F22 to K1 blocked TFPI inhibition of the FXa amidolytic activity and normalized hemostasis in hemophilia human A-like plasma and whole blood. Conclusion mAb2F22 blocked TFPI inhibition of both FVIIa and FXa activities and mapped a FXa exosite for binding to K1. It reversed TFPI feedback inhibition of TF/FVIIa-induced coagulation and restored clot formation in FVIII-neutralized human plasma and blood.
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Affiliation(s)
- C Augustsson
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | - A Svensson
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | - B Kjaer
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | - T-Y Chao
- Novo Nordisk Research Center China, Beijing, China
| | - X Wenjuan
- Novo Nordisk Research Center China, Beijing, China
| | - B O Krogh
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | - J Breinholt
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | - J T Clausen
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | - I Hilden
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | - H H Petersen
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | - L C Petersen
- Global Research, Novo Nordisk A/S, Måløv, Denmark
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20
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Heinzmann A, Hackeng TM, Hartmann R, Scheiflinger F, Dockal M, Rosing J, Peraramelli S, Thomassen S. Role of exosite binding modulators in the inhibition of Fxa by TFPI. Thromb Haemost 2018; 115:580-90. [DOI: 10.1160/th15-04-0354] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 10/21/2015] [Indexed: 11/05/2022]
Abstract
SummaryTissue factor pathway inhibitor (TFPI) down-regulates the extrinsic coagulation pathway by inhibiting FXa and FVIIa. Both TFPI and FXa interact with several plasma proteins (e. g. prothrombin, FV/FVa, protein S) and non-proteinaceous compounds (e. g. phospholipids, heparin). It was our aim to investigate effects of ligands that bind to FXa and TFPI on FXa inhibition by full-length TFPI (designated TFPI) and truncated TFPI (TFPI1-150). Inhibition of FXa by TFPI and TFPI1-150 and effects of phospholipids, heparin, prothrombin, FV, FVa, and protein S thereon was quantified from progress curves of conversion of the FXa-specific chromogenic substrate CS11-(65). Low concentrations negatively charged phospholipids (~10 μM) already maximally stimulated (up to 5- to 6-fold) FXa inhibition by TFPI. Unfractionated heparin at concentrations (0.2–1 U/ml) enhanced FXa inhibition by TFPI ~8-fold, but impaired inhibition at concentrations > 1 U/ml. Physiological protein S and FV concentrations both enhanced FXa inhibition by TFPI 2- to 3-fold. In contrast, thrombin-activated FV (FVa) impaired the ability of TFPI to inhibit FXa. FXa inhibition by TFPI1–150 was not affected by FV, FVa, protein S, phospholipids and heparin. TFPI potently inhibited FXa-catalysed prothrombin activation in the absence of FVa, but hardly inhibited prothrombin activation in the presence of thrombin-activated FVa. In conclusion, physiological concentrations TFPI (0.25–0.5 nM TFPI) inhibit FXa with a t1/2 between 3–15 minutes. Direct FXa inhibition by TFPI is modulated by physiological concentrations prothrombin, FV, FVa, protein S, phospholipids and heparin indicating the importance of these modulators for the in vivo anticoagulant activity of TFPI.
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21
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Non-factor replacement therapy for haemophilia: a current update. BLOOD TRANSFUSION = TRASFUSIONE DEL SANGUE 2018. [PMID: 29517971 DOI: 10.2450/2018.0272-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
One of the most challenging issues facing us in the treatment of haemophilia is the development of alloantibodies against infused factor VIII (FVIII) or factor IX (FIX). Inhibitors render factor replacement therapy ineffective, exposing patients to an unacceptably high risk of morbidity and mortality. Besides the well-known bypassing agents (i.e. activated prothrombin complex concentrate and recombinant activated factor VII) used to treat or prevent bleeding in haemophilia patients with inhibitors, there is growing interest in a new class of therapeutic agents which act by enhancing coagulation (i.e. emicizumab) or inhibiting anticoagulant pathways (i.e. fitusiran and concizumab). This review will focus on these innovative therapies, providing an update on their current stage of clinical development.
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22
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Ragni MV. Novel alternate hemostatic agents for patients with inhibitors: beyond bypass therapy. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2017; 2017:605-609. [PMID: 29222310 PMCID: PMC6142579 DOI: 10.1182/asheducation-2017.1.605] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Inhibitor formation is among the most severe complications of hemophilia treatment. With a cumulative incidence of ∼30% in those with severe hemophilia A and ∼3% in those with severe hemophilia B, inhibitors are caused by a T-cell response directed against infused coagulation factor; these inhibitors neutralize factor VIII or IX activity and disrupt normal hemostasis. Inhibitor patients become unresponsive to standard factor treatment and, as an alternative, use bypass treatment (eg, recombinant factor VIIa or factor VIII inhibitor bypass activity). However, response to bypass agents is poorer and the burden of disease is higher, with greater morbidity, hospitalization, cost, and mortality, than in noninhibitor patients. Furthermore, inhibitor formation interferes with prophylaxis to prevent bleeding episodes and is a contraindication to gene therapy. Thus, more effective therapies for inhibitor patients are greatly needed. In the last several years, there has been an explosion of novel alternative hemostatic agents for hemophilia patients with and without inhibitors. These agents take advantage of technologic manipulation of coagulation factors and natural anticoagulants to promote hemostasis. The approaches include the following: (1) mutants or mimics of coagulation factors, rendering them resistant to natural anticoagulants; or (2) knock-down or disruption of natural anticoagulants, preventing degradation of coagulation factors. The purpose of this article was to review these novel alternative hemostatic agents and their mechanisms of action, as well as the preliminary pharmacokinetic, safety, and efficacy data available from early-phase clinical trials.
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Affiliation(s)
- Margaret V Ragni
- Department of Medicine, Division Hematology/Oncology, University of Pittsburgh, and Hemophilia Center of Western Pennsylvania, Pittsburgh, PA
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23
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Ersayin A, Thomas A, Seyve L, Thielens N, Castellan M, Marlu R, Polack B, Dagher MC. Catalytically inactive Gla-domainless factor Xa binds to TFPI and restores ex vivo coagulation in hemophilia plasma. Haematologica 2017; 102:e483-e485. [PMID: 28983056 DOI: 10.3324/haematol.2017.174037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Atanur Ersayin
- University of Grenoble Alpes, CNRS, CHU Grenoble Alpes, Grenoble INP, TIMC-IMAG, Institute of Engineering, University Grenoble Alpes, Grenoble, France
| | - Aline Thomas
- University of Grenoble Alpes, CNRS, DPM, Grenoble, France
| | - Landry Seyve
- University of Grenoble Alpes, CNRS, CHU Grenoble Alpes, Grenoble INP, TIMC-IMAG, Institute of Engineering, University Grenoble Alpes, Grenoble, France
| | - Nicole Thielens
- University of Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
| | - Mathieu Castellan
- University of Grenoble Alpes, CNRS, CHU Grenoble Alpes, Grenoble INP, TIMC-IMAG, Institute of Engineering, University Grenoble Alpes, Grenoble, France
| | - Raphaël Marlu
- University of Grenoble Alpes, CNRS, CHU Grenoble Alpes, Grenoble INP, TIMC-IMAG, Institute of Engineering, University Grenoble Alpes, Grenoble, France
| | - Benoît Polack
- University of Grenoble Alpes, CNRS, CHU Grenoble Alpes, Grenoble INP, TIMC-IMAG, Institute of Engineering, University Grenoble Alpes, Grenoble, France
| | - Marie-Claire Dagher
- University of Grenoble Alpes, CNRS, CHU Grenoble Alpes, Grenoble INP, TIMC-IMAG, Institute of Engineering, University Grenoble Alpes, Grenoble, France
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24
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Zhang Z, Obianyo O, Dall E, Du Y, Fu H, Liu X, Kang SS, Song M, Yu SP, Cabrele C, Schubert M, Li X, Wang JZ, Brandstetter H, Ye K. Inhibition of delta-secretase improves cognitive functions in mouse models of Alzheimer's disease. Nat Commun 2017; 8:14740. [PMID: 28345579 PMCID: PMC5378956 DOI: 10.1038/ncomms14740] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Accepted: 01/26/2017] [Indexed: 12/21/2022] Open
Abstract
δ-secretase, also known as asparagine endopeptidase (AEP) or legumain, is a lysosomal cysteine protease that cleaves both amyloid precursor protein (APP) and tau, mediating the amyloid-β and tau pathology in Alzheimer's disease (AD). Here we report the therapeutic effect of an orally bioactive and brain permeable δ-secretase inhibitor in mouse models of AD. We performed a high-throughput screen and identified a non-toxic and selective δ-secretase inhibitor, termed compound 11, that specifically blocks δ-secretase but not other related cysteine proteases. Co-crystal structure analysis revealed a dual active site-directed and allosteric inhibition mode of this compound class. Chronic treatment of tau P301S and 5XFAD transgenic mice with this inhibitor reduces tau and APP cleavage, ameliorates synapse loss and augments long-term potentiation, resulting in protection of memory. Therefore, these findings demonstrate that this δ-secretase inhibitor may be an effective clinical therapeutic agent towards AD.
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Affiliation(s)
- Zhentao Zhang
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA.,Department of Neurology, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Obiamaka Obianyo
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Elfriede Dall
- Department of Molecular Biology, University of Salzburg, Salzburg A-5020, Austria
| | - Yuhong Du
- Department of Pharmacology, Emory Chemical Biology Discovery Center, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Haian Fu
- Department of Pharmacology, Emory Chemical Biology Discovery Center, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Xia Liu
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Seong Su Kang
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Mingke Song
- Department of Anesthesiology Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Shan-Ping Yu
- Department of Anesthesiology Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Chiara Cabrele
- Department of Molecular Biology, University of Salzburg, Salzburg A-5020, Austria
| | - Mario Schubert
- Department of Molecular Biology, University of Salzburg, Salzburg A-5020, Austria
| | - Xiaoguang Li
- Pathophysiology Department, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Jian-Zhi Wang
- Pathophysiology Department, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,Co-innovation Center of Neuroregeneration, Nantong 226001, China
| | - Hans Brandstetter
- Department of Molecular Biology, University of Salzburg, Salzburg A-5020, Austria
| | - Keqiang Ye
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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25
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Abstract
Hemophilia is a severe bleeding disorder treated by infusion of the missing blood coagulation protein, factor VIII or factor IX. The discovery and characterization of the anticoagulant protein tissue factor pathway inhibitor (TFPI) led to the realization that inhibition of TFPI activity could restore functional hemostasis through the extrinsic blood coagulation pathway in a manner that does not require the activity of factors VIII or IX. There are currently several therapeutic agents that inhibit TFPI in development for treatment of hemophilia. A comprehensive understanding of TFPI structure, biochemistry, and cellular expression is necessary to understand how it modulates bleeding in hemophilia and the physiological impact of therapeutic agents targeting TFPI.
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26
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Ragni MV. New and Emerging Agents for the Treatment of Hemophilia: Focus on Extended Half-Life Recombinant Clotting Proteins. Drugs 2016; 75:1587-600. [PMID: 26310188 DOI: 10.1007/s40265-015-0451-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Hemophilia A and B are X-linked disorders caused by deficient or defective clotting factor VIII (FVIII) or IX factor (FIX) proteins, and characterized by spontaneous or traumatic bleeding into joints and muscles. Previous use of plasma and plasma-derived clotting factors that lacked appropriate viral inactivation steps in manufacturing led to significant morbidity associated with transfusion-transmitted HIV and hepatitis C virus (HCV). The development of recombinant proteins revolutionized their treatment, and, with no new HIV or HCV infection via clotting proteins for nearly 30 years, greatly improved their lifespan, which now approaches that of the general population, and with the same risks for aging complications. Novel long-acting factor proteins are being licensed to extend FVIII and FIX half-life, thereby reducing infusion frequency and potentially bleed frequency and associated morbidity. Further, novel therapeutics which take advantage of new technologies, including siRNA, monoclonal antibody, and small peptide inhibition technologies, have the potential to simplify treatment and improve outcomes for those with inhibitors.
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Affiliation(s)
- Margaret V Ragni
- Division Hematology/Oncology, Department of Medicine, Hemophilia Center of Western Pennsylvania, University of Pittsburgh, 3636 Boulevard of the Allies, Pittsburgh, PA, 15213-4306, USA.
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27
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Leissinger CA. Advances in the clinical management of inhibitors in hemophilia A and B. Semin Hematol 2015; 53:20-7. [PMID: 26805903 DOI: 10.1053/j.seminhematol.2015.10.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2004] [Revised: 11/05/2004] [Accepted: 12/01/2005] [Indexed: 01/25/2023]
Abstract
Inhibitors to factor (F)VIII or FIX are the most serious and challenging complication of hemophilia treatment, increasing morbidity and mortality because bleeds no longer respond to standard clotting factor replacement therapy. For patients with high-titer inhibitors, immune tolerance induction achieved through regular factor exposure is the only proven therapy capable of Inhibitor eradication and is almost always indicated for inhibitors of recent onset. Bypassing therapy is used to treat and prevent bleeding, but neither of the two currently available bypassing agents has the predictable hemostatic efficacy of factor replacement in hemophilia patients without inhibitors. Major research efforts are focused on the development of new, more potent therapies for the management of patients with inhibitors.
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Affiliation(s)
- Cindy A Leissinger
- Departments of Medicine, Pediatrics, and Pathology, Tulane University School of Medicine, New Orleans, LA, USA.
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28
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Abstract
Tissue factor pathway inhibitor (TFPI) dampens the initiation of blood coagulation by inhibiting two potent procoagulant complexes, tissue factor-factor VIIa (TF-FVIIa) and early forms of prothrombinase. TFPI isoforms, TFPIα and TFPIβ, result from alternative splicing of mRNA, producing distinct C-terminal ends of the two proteins. Both isoforms inhibit TF-FVIIa, but only TFPIα can inhibit early forms of prothrombinase by binding of its positively charged C-terminus with high affinity to the acidic B-domain exosite of FVa, which is generated upon activation by FXa. TFPIα and TFPIβ are produced in cultured human endothelial cells, while platelets contain only TFPIα. Knowledge of the anticoagulant mechanisms and tissue expression patterns of TFPIα and TFPIβ have improved our understanding of the phenotypes observed in different mouse models of TFPI deficiency, the east Texas bleeding disorder, and the development of pharmaceutical agents that block TFPI function to treat hemophilia.
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Affiliation(s)
- S A Maroney
- Blood Research Institute, Blood Center of Wisconsin, Milwaukee, WI, USA
| | - A E Mast
- Blood Research Institute, Blood Center of Wisconsin, Milwaukee, WI, USA
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
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Percy CL, Hartmann R, Jones RM, Balachandran S, Mehta D, Dockal M, Scheiflinger F, O’Donnell VB, Hall JE, Collins PW. Correcting thrombin generation ex vivo using different haemostatic agents following cardiac surgery requiring the use of cardiopulmonary bypass. Blood Coagul Fibrinolysis 2015; 26:357-67. [PMID: 25928274 PMCID: PMC4888920 DOI: 10.1097/mbc.0000000000000243] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 09/10/2014] [Accepted: 11/03/2014] [Indexed: 11/25/2022]
Abstract
Recently, lower thrombin generation has been associated with excess bleeding post-cardiopulmonary bypass (CPB). Therefore, treatment to correct thrombin generation is a potentially important aspect of management of bleeding in this group of patients. The objective of the present study was to investigate the effects of fresh frozen plasma (FFP), recombinant factor VIIa (rFVIIa), prothrombin complex concentrate (PCC) and tissue factor pathway inhibitor (TFPI) inhibition on thrombin generation when added ex vivo to the plasma of patients who had undergone cardiac surgery requiring CPB. Patients undergoing elective cardiac surgery were recruited. Blood samples were collected before administration of heparin and 30 min after its reversal. Thrombin generation was measured in the presence and absence of different concentrations of FFP, rFVIIa, PCC and an anti-TFPI antibody. A total of 102 patients were recruited. Thrombin generation following CPB was lower compared with pre-CPB (median endogenous thrombin potential pre-CPB 339 nmol/l per min, post-CPB 155 nmol/l per min, P < 0.0001; median peak thrombin pre-CPB 35 nmol/l, post-CPB 11 nmol/l, P < 0.0001). Coagulation factors and anticoagulants decreased, apart from total TFPI, which increased (55-111 ng/ml, P < 0.0001), and VWF (144-170 IU/dl, P < 0.0001). Thrombin generation was corrected to pre-CPB levels by the equivalent of 15 ml/kg FFP, 45 μg/kg rFVIIa and 25 U/kg of PCC. Inhibition of TFPI resulted in an enhancement of thrombin generation significantly beyond pre-CPB levels. This study shows that FFP, rFVIIa, PCC and inhibition of TFPI correct thrombin generation in the plasma of patients who have undergone surgery requiring CPB. Inhibition of TFPI may be a further potential therapeutic strategy for managing bleeding in this group of patients.
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Affiliation(s)
- Charles L. Percy
- Institute of Infection and Immunity, Cardiff University School of Medicine, Heath Park, Cardiff, UK
| | | | - Rhidian M. Jones
- Institute of Infection and Immunity, Cardiff University School of Medicine, Heath Park, Cardiff, UK
| | | | - Dheeraj Mehta
- Department of Cardiothoracic Surgery, University Hospital of Wales, Heath Park, Cardiff, UK
| | | | | | - Valerie B. O’Donnell
- Institute of Infection and Immunity, Cardiff University School of Medicine, Heath Park, Cardiff, UK
| | - Judith E. Hall
- Institute of Infection and Immunity, Cardiff University School of Medicine, Heath Park, Cardiff, UK
| | - Peter W. Collins
- Institute of Infection and Immunity, Cardiff University School of Medicine, Heath Park, Cardiff, UK
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Zeller MP, Al-Habsi KS, Golder M, Walsh GM, Sheffield WP. Plasma and Plasma Protein Product Transfusion: A Canadian Blood Services Centre for Innovation Symposium. Transfus Med Rev 2015; 29:181-94. [PMID: 25862281 DOI: 10.1016/j.tmrv.2015.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Revised: 03/12/2015] [Accepted: 03/13/2015] [Indexed: 12/27/2022]
Abstract
Plasma obtained via whole blood donation processing or via apheresis technology can either be transfused directly to patients or pooled and fractionated into plasma protein products that are concentrates of 1 or more purified plasma protein. The evidence base supporting clinical efficacy in most of the indications for which plasma is transfused is weak, whereas high-quality evidence supports the efficacy of plasma protein products in at least some of the clinical settings in which they are used. Transfusable plasma utilization remains composed in part of applications that fall outside of clinical practice guidelines. Plasma contains all of the soluble coagulation factors and is frequently transfused in efforts to restore or reinforce patient hemostasis. The biochemical complexities of coagulation have in recent years been rationalized in newer cell-based models that supplement the cascade hypothesis. Efforts to normalize widely used clinical hemostasis screening test values by plasma transfusion are thought to be misplaced, but superior rapid tests have been slow to emerge. The advent of non-vitamin K-dependent oral anticoagulants has brought new challenges to clinical laboratories in plasma testing and to clinicians needing to reverse non-vitamin K-dependent oral anticoagulants urgently. Current plasma-related controversies include prophylactic plasma transfusion before invasive procedures, plasma vs prothrombin complex concentrates for urgent warfarin reversal, and the utility of increased ratios of plasma to red blood cell units transfused in massive transfusion protocols. The first recombinant plasma protein products to reach the clinic were recombinant hemophilia treatment products, and these donor-free equivalents to factors VIII and IX are now being supplemented with novel products whose circulatory half-lives have been increased by chemical modification or genetic fusion. Achieving optimal plasma utilization is an ongoing challenge in the interconnected worlds of transfusable plasma, plasma protein products, and recombinant and engineered replacements.
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Affiliation(s)
- Michelle P Zeller
- Centre for Innovation, Medical Services and Innovation, Canadian Blood Services, Hamilton, Ottawa, Vancouver, Canada; Department of Medicine, McMaster University, Hamilton, Canada
| | - Khalid S Al-Habsi
- Centre for Innovation, Medical Services and Innovation, Canadian Blood Services, Hamilton, Ottawa, Vancouver, Canada; Department of Medicine, McMaster University, Hamilton, Canada
| | - Mia Golder
- Centre for Innovation, Medical Services and Innovation, Canadian Blood Services, Hamilton, Ottawa, Vancouver, Canada
| | - Geraldine M Walsh
- Centre for Innovation, Medical Services and Innovation, Canadian Blood Services, Hamilton, Ottawa, Vancouver, Canada
| | - William P Sheffield
- Centre for Innovation, Medical Services and Innovation, Canadian Blood Services, Hamilton, Ottawa, Vancouver, Canada; Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada.
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Monahan PE. Emerging genetic and pharmacologic therapies for controlling hemostasis: beyond recombinant clotting factors. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2015; 2015:33-40. [PMID: 26637698 DOI: 10.1182/asheducation-2015.1.33] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
For more than 3 decades, the scientific community has pursued gene correction of hemophilia, with the goal that an individual with congenitally deficient factor VIII or factor IX might synthesize adequate endogenous clotting factor to be relieved of burdensome repeated clotting factor infusions, as well as the emotional weight of continuous hemorrhage risk. Recent reports of successful factor IX gene therapy and partial correction of the bleeding phenotype have raised the bar for success for a robust crop of new clinical gene therapy efforts for both hemophilia A and B. At the same time that gene therapy is gaining momentum, suggesting the possibility of relief from regular intravenous coagulation protein replacement, a number of innovative technologies that enhance hemostatic potential independently of replacement factor administration are demonstrating success in human clinical application. Human clinical trial progress is reviewed regarding a recombinant bispecific IgG antibody to factors IXa and X that mimics factor VIII cofactor activity, as well as monoclonal antibody and short interfering RNA strategies that demonstrate hemostatic efficacy via opposing inhibitors of coagulation. These strategies, associated with prolonged hemostatic potential following subcutaneous (ACE910, ALN-AT3, Concizumab) or single administration (eg, gene therapy) make it possible to imagine a day when recombinant clotting factor administration, rather than being a daily preoccupation, is relegated to an adjunctive role in supporting more novel standard of care therapies.
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Affiliation(s)
- Paul E Monahan
- Gene Therapy Center, Department of Pediatrics, and Harold R. Roberts Comprehensive Hemophilia Diagnostic and Treatment Center, University of North Carolina, Chapel Hill, NC
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32
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Shetty S, Ghosh K. Novel therapeutic approaches for haemophilia. Haemophilia 2014; 21:152-161. [DOI: 10.1111/hae.12615] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2014] [Indexed: 01/11/2023]
Affiliation(s)
- S. Shetty
- Department of Thrombosis and Haemostasis National Institute of Immunohaematology (ICMR) KEM Hospital Mumbai India
| | - K. Ghosh
- Department of Thrombosis and Haemostasis National Institute of Immunohaematology (ICMR) KEM Hospital Mumbai India
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Kempton CL, Meeks SL. Toward optimal therapy for inhibitors in hemophilia. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2014; 2014:364-371. [PMID: 25696880 DOI: 10.1182/asheducation-2014.1.364] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Treatment of patients with hemophilia A and B has undergone significant advances during the past 2 decades. However, despite these advances, the development of antibodies that inhibit the function of infused clotting factor remains a major challenge and is considered the most significant complication of hemophilia treatment. This chapter reviews current tools available for the care of patients with inhibitors and highlights areas where progress is imminent or strongly needed. For management of bleeding, bypassing agents remain the mainstay of therapy. Recombinant factor VIIa and activated prothrombin complex concentrates are similarly effective in populations of patients with hemophilia and inhibitors; however, individuals may show a better response to one agent over another. Recent studies have shown that prophylaxis with bypassing agents can reduce bleeding episodes by ∼50%-80%. The prophylactic use of bypassing agents is an important tool to reduce morbidity in patients before they undergo immune tolerance induction (ITI) and in those with persistent high titer inhibitors, but cost and lack of convenience remain barriers. Because of the significant burden that inhibitors add to the individual patient and the health care system, inhibitor eradication should be pursued in as many patients as possible. ITI is an effective tool, particularly in patients with severe hemophilia A and good risk profiles, and leads to a return to a normal factor VIII response in ∼60% of patients. However, for the group of patients who fail to respond to ITI or have hemophilia B, new and improved tools are needed.
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Affiliation(s)
- Christine L Kempton
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, and Department of Hematology and Medical Oncology, Emory University, Atlanta, GA
| | - Shannon L Meeks
- Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, and
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Abstract
Abstract
Treatment of patients with hemophilia A and B has undergone significant advances during the past 2 decades. However, despite these advances, the development of antibodies that inhibit the function of infused clotting factor remains a major challenge and is considered the most significant complication of hemophilia treatment. This chapter reviews current tools available for the care of patients with inhibitors and highlights areas where progress is imminent or strongly needed. For management of bleeding, bypassing agents remain the mainstay of therapy. Recombinant factor VIIa and activated prothrombin complex concentrates are similarly effective in populations of patients with hemophilia and inhibitors; however, individuals may show a better response to one agent over another. Recent studies have shown that prophylaxis with bypassing agents can reduce bleeding episodes by ∼50%-80%. The prophylactic use of bypassing agents is an important tool to reduce morbidity in patients before they undergo immune tolerance induction (ITI) and in those with persistent high titer inhibitors, but cost and lack of convenience remain barriers. Because of the significant burden that inhibitors add to the individual patient and the health care system, inhibitor eradication should be pursued in as many patients as possible. ITI is an effective tool, particularly in patients with severe hemophilia A and good risk profiles, and leads to a return to a normal factor VIII response in ∼60% of patients. However, for the group of patients who fail to respond to ITI or have hemophilia B, new and improved tools are needed.
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Abstract
Recent studies of the anticoagulant activities of the tissue factor (TF) pathway inhibitor (TFPI) isoforms, TFPIα and TFPIβ, have provided new insight into the biochemical and physiological mechanisms that underlie bleeding and clotting disorders. TFPIα and TFPIβ have tissue-specific expression patterns and anticoagulant activities. An alternative splicing event in the 5' untranslated region allows for translational regulation of TFPIβ expression. TFPIα has 3 Kunitz-type inhibitor domains (K1, K2, K3) and a basic C terminus, whereas TFPIβ has the K1 and K2 domains attached to a glycosylphosphatidyl inositol-anchored C terminus. TFPIα is the only isoform present in platelets, whereas endothelial cells produce both isoforms, secreting TFPIα and expressing TFPIβ on the cell surface. TFPIα and TFPIβ inhibit both TF-factor VIIa-dependent factor Xa (FXa) generation and free FXa. Protein S enhances FXa inhibition by TFPIα. TFPIα produces isoform-specific inhibition of prothrombinase during the initiation of coagulation, an anticoagulant activity that requires an exosite interaction between its basic C terminus and an acidic region in the factor Va B domain. Platelet TFPIα may be optimally localized to dampen initial thrombin generation. Similarly, endothelial TFPIβ may be optimally localized to inhibit processes that occur when endothelial TF is present, such as during the inflammatory response.
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Miguelino MG, Powell JS. Clinical utility and patient perspectives on the use of extended half-life rFIXFc in the management of hemophilia B. Patient Prefer Adherence 2014; 8:1073-83. [PMID: 25143713 PMCID: PMC4133029 DOI: 10.2147/ppa.s54951] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Hemophilia B is an X-linked genetic disease caused by mutation of the gene for coagulation protein factor IX (FIX), with an incidence of approximately once every 30,000 male births in all populations and ethnic groups. When severe, the disease leads to spontaneous life threatening bleeding episodes. When untreated, most patients die from bleeding complications before 25 years of age. Current therapy requires frequent intravenous infusions of therapeutic recombinant or plasma-derived protein concentrates containing FIX. Most patients administer the infusions at home every few days, and must limit their physical activities to avoid abnormal bleeding when the FIX activity levels are below normal. After completing the pivotal Phase III clinical trial, a new therapeutic FIX preparation that has been engineered for an extended half-life in circulation, received regulatory approval in March 2014 in Canada and the US. This new FIX represents a major therapeutic advance for patients with hemophilia B. The half-life is prolonged due to fusion of the native FIX molecule with the normal constant region of immunoglobulin G. This fusion molecule then follows the normal immunoglobulin recirculation pathways through endothelial cells, resulting in prolonged times in circulation. In the clinical trials, over 150 patients successfully used eftrenonacog alfa regularly for more than 1 year to prevent spontaneous bleeding, to successfully treat any bleeding episodes, and to provide effective coagulation for major surgery. All infusions were well tolerated and effective, with no inhibitors detected and no safety concerns. This promising therapy should allow patients to use fewer infusions to maintain appropriate FIX activity levels in all clinical settings.
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Affiliation(s)
- Maricel G Miguelino
- Division of Hematology and Oncology, University of California Davis Medical Center, Sacramento, CA, USA
| | - Jerry S Powell
- Division of Hematology and Oncology, University of California Davis Medical Center, Sacramento, CA, USA
- Correspondence: Jerry S Powell, Division of Hematology and Oncology, Suite 3016, University of California Davis Medical Center, 4501 X Street, Sacramento, CA 95817, USA, Tel +1 916 734 3772, Fax +1 916 734 7946, Email
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