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Blood May 2012In high-income countries, the large availability of coagulation factors for replacement therapy of patients with hemophilia A has raised the life expectancy of these... (Comparative Study)
Comparative Study Review
In high-income countries, the large availability of coagulation factors for replacement therapy of patients with hemophilia A has raised the life expectancy of these lifelong bleeders to that of males from the general population. The practicing clinician is offered a multitude of choices among several commercial brands of factor VIII extracted from human plasma or engineered from mammalian cell cultures by means of recombinant DNA technology. This article has the goal to offer our opinions on how to choose among the different products, that we consider interchangeable relevant to their clinical efficacy in the control of bleeding and safety from pathogen transmission. Hence, the main determinants of our choices are price and the risk of occurrence of factor VIII inhibitory alloantibodies. With this as background, we present the rationale underlying the choices for different categories of patients with severe hemophilia A: previously untreated patients, multiply treated patients, and patients undergoing immune tolerance induction with large doses of factor VIII to eradicate inhibitors. Mention is also made to the possible strategies that should be implemented to make available coagulation factors for replacement therapy in developing countries.
Topics: Animals; Blood-Borne Pathogens; Cell Line; Child; Child, Preschool; Developed Countries; Developing Countries; Drug Contamination; Drug Costs; Factor VIII; Hemophilia A; Humans; Immune Tolerance; Infant; Insurance, Health, Reimbursement; Isoantibodies; Italy; Male; Patient Selection; Randomized Controlled Trials as Topic; Recombinant Proteins; Species Specificity
PubMed: 22411872
DOI: 10.1182/blood-2012-01-394411 -
Blood Advances May 2023von Willebrand factor (VWF) is the protective carrier of procoagulant factor VIII (FVIII) in the shear forces of the circulation, prolonging its half-life and delivering...
von Willebrand factor (VWF) is the protective carrier of procoagulant factor VIII (FVIII) in the shear forces of the circulation, prolonging its half-life and delivering it to the developing thrombus. Using force spectroscopy, VWF-FVIII complex formation is characterized by catch-bond behavior in which force first decelerates then accelerates bond dissociation. Patients with mutations in VWF at the FVIII binding site phenocopies hemophilia A and the most common mutations are of cysteine residues involving multiple disulfide bonds. From differential cysteine alkylation and mass spectrometry experiments, 13 VWF disulfide bonds at the FVIII binding site were found to exist in formed and unformed states, and binding of FVIII results in partial formation of 12 of the VWF bonds. Force spectroscopy studies indicate that the VWF-FVIII bond stiffens in response to force and this feature of the interaction is ablated when VWF disulfide bonds are prevented from forming, resulting in slip-only bond behavior. Exposure of VWF to pathological fluid shear forces ex vivo and in vivo causes partial cleavage of all 13 disulfide bonds, further supporting their malleable nature. These findings demonstrate that FVIII binding to VWF involves dynamic changes in the covalent states of several VWF disulfides that are required for productive interaction in physiological shear forces.
Topics: Humans; Cysteine; Factor VIII; Hemophilia A; Hemostatics; Thrombosis; von Willebrand Factor
PubMed: 36240294
DOI: 10.1182/bloodadvances.2022008650 -
PloS One 2018Prophylactic injections of factor VIII reduce the incidence of bleeds and slow the development of joint damage in people with hemophilia. The aim of this study was to...
BACKGROUND & AIMS
Prophylactic injections of factor VIII reduce the incidence of bleeds and slow the development of joint damage in people with hemophilia. The aim of this study was to identify optimal person-specific prophylaxis regimens for children with hemophilia A.
METHODS
Analytic and numerical methods were used to identify prophylaxis regimens which maximize the time for which plasma factor VIII concentrations exceed a threshold, maximize the lowest plasma factor VIII concentrations, and minimize risk of bleeds.
RESULTS
It was demonstrated analytically that, for any injection schedule, the regimen that maximizes the lowest factor VIII concentration involves sharing doses between injections so that all of the trough concentrations in a prophylaxis cycle are equal. Numerical methods were used to identify optimal prophylaxis schedules and explore the trade-offs between efficacy and acceptability of different prophylaxis regimens. The prophylaxis regimen which minimizes risk of bleeds depends on the person's pattern of physical activity and may differ greatly from prophylaxis regimens that optimize pharmacokinetic parameters. Prophylaxis regimens which minimize risk of bleeds also differ from prophylaxis regimens that are typically prescribed. Predictions about which regimen is optimal are sensitive to estimates of the effects on risk of bleeds of factor VIII concentration and physical activity.
CONCLUSION
The methods described here can be used to identify optimal, person-specific prophylaxis regimens for children with hemophilia A.
Topics: Child; Factor VIII; Hemophilia A; Hemorrhage; Humans; Male
PubMed: 29447219
DOI: 10.1371/journal.pone.0192783 -
Haemophilia : the Official Journal of... Jan 2016BAX 855 is a PEGylated human full-length recombinant factor VIII (rFVIII) based on licensed rFVIII (ADVATE). The applied PEGylation technology has been optimized to...
INTRODUCTION
BAX 855 is a PEGylated human full-length recombinant factor VIII (rFVIII) based on licensed rFVIII (ADVATE). The applied PEGylation technology has been optimized to retain functionality of the FVIII molecule, improve its pharmacokinetic properties and allow less frequent injections while maintaining efficacy.
AIM
The aim of this study was to confirm that the excellent safety profile of ADVATE remains unchanged after PEGylation.
METHODS
Non-clinical safety studies with BAX 855 and its respective unbound polyethylene glycol (PEG) were conducted in several species. The distribution of a single dose of radiolabelled BAX 855 was further investigated in rats. Publically available safety data on PEG alone and PEGylated biomolecules were summarized and reviewed for specific safety findings attributable to PEG or PEGylated biopharmaceuticals.
RESULTS
Safety pharmacology studies in rabbits and macaques and repeated dose toxicity studies in rats and macaques identified no safety issues. Results of a distribution study in rats administered radiolabelled BAX 855 showed that radioactivity was completely excreted; urine was the major elimination route. A 28-day study in rats dosed with the unbound PEG constituent (PEG2ru20KCOOH) of BAX 855 showed no adverse or non-adverse effects. Safety data for PEG and PEG-protein conjugates indicate no safety concerns associated with PEG at clinically relevant dose levels. Although vacuolation of certain cell types has been reported in mammals, no such vacuolation was observed with BAX 855 or with the unbound PEG constituent.
CONCLUSION
Non-clinical safety evaluation of PEG and BAX 855 identified no safety signals; the compound is now in clinical development for the treatment of patients with haemophilia A.
Topics: Animals; Factor VIII; Female; Humans; Male; Polyethylene Glycols; Rabbits; Rats; Safety; Tissue Distribution; Vacuoles
PubMed: 26219204
DOI: 10.1111/hae.12762 -
Journal of Thrombosis and Haemostasis :... Nov 2022Substantial phenotypic heterogeneity exists in endothelial cells and while much of this heterogeneity results from local microenvironments, epigenetic modifications also...
BACKGROUND
Substantial phenotypic heterogeneity exists in endothelial cells and while much of this heterogeneity results from local microenvironments, epigenetic modifications also contribute.
METHODS
Cultured human umbilical vein endothelial cells, human pulmonary microvascular endothelial cells, human hepatic sinusoidal endothelial cells, human lymphatic endothelial cells (hLECs), and two different isolations of endothelial colony forming cells (ECFCs) were assessed for levels of factor VIII (FVIII) and von Willebrand factor (VWF) RNA and protein. The intracellular location and co-localization of both proteins was evaluated with immunofluorescence microscopy and stimulated release toof FVIII and VWF from Weibel-Palade bodies (WPBs) was evaluated. Changes in expression of FVIII and VWF RNA after hLECs and ECFCs were exposed to 2 or 15 dynes/cm of laminar shear stress were also assessed.
RESULTS
We observed considerable heterogeneity in FVIII and VWF expression among the endothelial cells. With the exception of hLECs, FVIII RNA and protein were barely detectable in any of the endothelial cells and a reciprocal relationship between levels of FVIII and VWF appears to exist. When FVIII and VWF are co-expressed, they do not consistently co-localize in the cytoplasm. However, in hLECs where significantly higher levels of FVIII are expressed, FVIII and VWF co-localize in WPBs and are released together when stimulated. Expression of both FVIII and VWF is markedly reduced when hLECs are exposed to higher or lower levels of laminar shear stress, while in ECFCs there is a minimal response for both proteins.
CONCLUSIONS
Variable levels of FVIII and VWF RNA and protein exist in a subset of cultured human endothelial cells. Higher levels of FVIII present in hLECs co-localize with VWF and are released together when exposed to a secretagogue.
Topics: Humans; von Willebrand Factor; Factor VIII; Secretagogues; Hemostatics; Human Umbilical Vein Endothelial Cells; RNA
PubMed: 35950488
DOI: 10.1111/jth.15841 -
Hamostaseologie Aug 2022Haemophilia A (HA) and B (HB) are X-linked hereditary bleeding disorders caused by lack of activity of coagulation factors VIII (FVIII) or IX (FIX), respectively.... (Review)
Review
Haemophilia A (HA) and B (HB) are X-linked hereditary bleeding disorders caused by lack of activity of coagulation factors VIII (FVIII) or IX (FIX), respectively. Besides conventional products, modern replacement therapies include FVIII or FIX concentrates with an extended half-life (EHL-FVIII/FIX). Two main strategies for measuring plasma FVIII or FIX activity are applied: the one-stage clotting assay (OSCA) and the chromogenic substrate assay (CSA), both calibrated against plasma (FVIII/FIX) standards. Due to the structural modifications of EHL-FVIII/FIX, reagent-dependent assay discrepancies have been described when measuring the activity of these molecules. Assay discrepancies have also been observed in FVIII/FIX gene therapy approaches. On the other hand, nonfactor replacement by the bispecific antibody emicizumab, a FVIIIa-mimicking molecule, artificially shortens activated partial thromboplastin time-based clotting times, making standard OSCAs inapplicable for analysis of samples from patients treated with this drug. In this review, we aim to give an overview on both, the currently applied and future therapies in HA and HB with or without inhibitors and corresponding test systems suitable for accompanying diagnostics.
Topics: Blood Coagulation Tests; Factor VIII; Half-Life; Hemophilia A; Hemostatics; Humans; Partial Thromboplastin Time
PubMed: 35104901
DOI: 10.1055/a-1665-6232 -
Journal of Thrombosis and Haemostasis :... Sep 2023Mechanisms of iron clearance from hemophilic joints are unknown.
BACKGROUND
Mechanisms of iron clearance from hemophilic joints are unknown.
OBJECTIVES
To better understand mechanisms of iron clearance following joint bleeding in a mouse model of hemophilia.
METHODS
Hemarthrosis was induced by subpatellar puncture in factor VIII (FVIII)-deficient (FVII) mice, +/- periprocedural recombinant human FVIII, and hypocoagulable (BALB/c) mice. BALB/c mice experienced transient FVIII deficiency (anti-FVIII antibody) at the time of injury combined with warfarin-induced hypocoagulability. Synovial tissue was harvested weekly up to 6 weeks after injury for histological analysis, ferric iron and macrophage accumulation (CD68), blood and lymphatic vessel remodeling (αSMA; LYVE1). Synovial RNA sequencing was performed for FVIII mice at days 0, 3, and 14 after injury to quantify expression changes of iron regulators and lymphatic markers.
RESULTS
Bleed volumes were similar in FVIII and BALB/c mice. However, pronounced and prolonged synovial iron accumulation colocalizing with macrophages and impaired lymphangiogenesis were detected only in FVIII mice and were prevented by periprocedural FVIII. Gene expression changes involved in iron handling (some genes with dual roles in inflammation) and lymphatic markers supported proinflammatory milieu with iron retention and disturbed lymphangiogenesis.
CONCLUSION
Accumulation and delayed clearance of iron-laden macrophages were associated with defective lymphangiogenesis after hemarthrosis in FVIII mice. The absence of such findings in BALB/c mice suggests that intact lymphatics are required for removal of iron-laden macrophages and that these processes depend on FVIII availability. Studies to elucidate the biological mechanisms of disturbed lymphangiogenesis in hemophilia appear critical to develop new therapeutic targets.
Topics: Mice; Humans; Animals; Factor VIII; Hemarthrosis; Hemophilia A; Lymphangiogenesis; Hemostatics; Disease Models, Animal; Iron
PubMed: 37116753
DOI: 10.1016/j.jtha.2023.04.022 -
European Journal of Haematology Nov 2014The development of a new recombinant factor VIII was designed and implemented to answer a number of unmet needs of patients affected by hemophilia A. Turoctocog alfa is... (Review)
Review
The development of a new recombinant factor VIII was designed and implemented to answer a number of unmet needs of patients affected by hemophilia A. Turoctocog alfa is bioengineered in a specific Chinese hamster ovary clone to present translational and posttranslational characteristics (sulphation, glycosylation) biosimilar to natural circulating forms of FVIII, with the aim to devoid any minimal change which may impact immunogenicity and antigenicity of recombinant protein. Both producer cell line and media are maintained free of any animal or human plasma derivative. Downstream processes of purification are performed by five steps (immunoaffinity chromatography, ion-exchange chromatography, virus inactivation by means of solvent-detergent treatment and nanofiltration, and to end with gel filtration), to provide the best possible margin of safety from known and unknown infectious agents. Large clinical trials seem to confirm the expectations placed in Turoctocog alfa in terms of high quality and safety of recombinant FVIII toward the goal of overcoming actual and future challenges of hemophilia therapy.
Topics: Animals; Biomarkers, Pharmacological; CHO Cells; Cricetulus; Drug Industry; Factor VIII; Gene Expression; Glycosylation; Hemophilia A; Humans; Practice Guidelines as Topic; Protein Modification, Translational; Protein Processing, Post-Translational; Recombinant Proteins; Sulfates
PubMed: 24766411
DOI: 10.1111/ejh.12359 -
International Journal of Laboratory... Apr 2019Variability in FVIII measurement is a recognized problem. There are limited data for samples containing recombinant Factor VIII Fc fusion protein (rFVIIIFc). Many...
Clotting and chromogenic factor VIII assay variability in post-infusion and spiked samples containing full-length recombinant FVIII or recombinant factor VIII Fc fusion protein (rFVIIIFc).
INTRODUCTION
Variability in FVIII measurement is a recognized problem. There are limited data for samples containing recombinant Factor VIII Fc fusion protein (rFVIIIFc). Many studies use samples for which factor concentrate has been spiked into FVIII deficient plasma in vitro. This approach requires validation.
AIM/METHODS
Four samples were distributed in a UK National External Quality Assessment Scheme for Blood Coagulation (NEQAS BC) survey. One contained Advate (full-length recombinant FVIII) (rFVIII) added to FVIII deficient plasma, one was from a severe haemophilia A patient after infusion of Advate, one was prepared by addition of rFVIIIFc (marketed as Elocta/Eloctate) to FVIII deficient plasma and the fourth was collected from a severe haemophilia A patient following rFVIIIFc (Eloctate) infusion. Fifty-three haemophilia centres (UK and Scandinavia) performed one-stage FVIII assays and 27 performed chromogenic FVIII assays.
RESULTS/CONCLUSIONS
One-stage assays gave significantly lower results than chromogenic assays by 7% (P < 0.01) and 13%(P < 0.001) for post-Advate and Advate spiked samples, and by 22% (P < 0.001) and 23% (P < 0.001) for post-rFVIIIFc and rFVIIIFc spiked samples. The interlaboratory variation was similar for all samples, with CVs of 12%-16% (chromogenic) and 10%-13% (one stage). The data indicate that either product can be safely monitored by one-stage or chromogenic assay. Spiked samples behaved in a similar way to post-infusion samples for both products and could be substituted for post-infusion samples for use in proficiency testing exercises (ie, samples were commutable).
Topics: Blood Coagulation; Blood Coagulation Tests; Factor VIII; Humans; Immunoglobulin Fc Fragments; Recombinant Fusion Proteins
PubMed: 30556650
DOI: 10.1111/ijlh.12940 -
Haemophilia : the Official Journal of... Jul 2012
Review
Topics: Factor VIII; Hemophilia A; History, 20th Century; Humans; Recombinant Proteins
PubMed: 22512315
DOI: 10.1111/j.1365-2516.2012.02804.x