Factor VIII activity and bleeding risk during prophylaxis for severe hemophilia A: a population pharmacokinetic model

Abstract Orthotopic liver transplantation (OLT) is an effective treatment for both hepatitis C associated cirrhosis, hepatocellular carcinoma, and hemophilia A. Factor VIII activity usually increases into the normal range. Only a few patients with hemophilia complicated by an inhibitor have undergone OLT with both successful outcomes and uncontrolled bleeding being reported. We report early results of OLT in a middle-aged white male severe hemophilia A patient with a history of a high responding inhibitor (historical high - 70 Bethesda units) who had been on immune tolerance for greater than 10 years prior to transplant. A regimen of 40 u/kg of Factor VIII three times per week successfully suppressed inhibitor titers to less than 2 Bethesda units in the previous years. Hand surgery was managed with Factor VII infusions in the year prior to OLT with good results. At the time of transplantation, his inhibitor titer was 0.7 B.U. Due to his history of non-linear kinetics with factor VIII infusion, (5% of a dose remaining at 24 hours), frequent bolus dosing during surgery was employed. He received 10,500 units (116 units/kg) prior to the incision with smaller doses repeated every 2–4 hours. During the operation and the 24 hr immediately post op he required another 27,300 units (300 units/kg) of factor VIII infusion to maintain activity between 61–122%. On post op day 1 he required 46 units/kg to keep activity between 60.2–108%. On post op day 2 he required 35 units/kg to keep activity between 36.8–68.4%. His immunosuppresion included tacrolimus, mycophenolate, and solumedrol taper of 120 mg on day 2, 80 mg on day 3, 40 mg on day 4, and 20 mg day 5. From day 6 to day 8, his total bilirubin increased to 15 and his requirement for Factor VIII also increased to 70 units/kg daily for 3 days to keep his activity between 33.1% to 71.2%. His immunosuppression was increased because of possible acute rejection and solumedrol 500 mg IV was given daily for 3 days. On day 9 his requirement for factor decreased to 11.6 units/kg daily for 4 additional days. Solumedrol was tapered off to prednisone 10 mg po daily. On day 13 post operation, Factor VIII replacement was stopped and his activity was 56.8%, which gradually rose to 81% on day 25. We conclude: Orthotopic liver transplantation was successful in a hemophilia A inhibitor patient on long term immune tolerance. Factor VIII production by the transplanted liver suppressed the inhibitor and normalized Factor VIII activity up to 4 weeks post transplant. Close follow-up will be required.

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Thromboelastography during coronary artery bypass grafting surgery of severe hemophilia A patient – the effect of heparin and protamine on factor VIII activity

Blood Coagulation & Fibrinolysis ◽

10.1097/mbc.0000000000000575 ◽

2017 ◽

Vol 28 (4) ◽

pp. 329-333 ◽

Cited By ~ 8

Author(s):

Mudi Misgav ◽

Tal Mandelbaum ◽

Yigal Kassif ◽

Haim Berkenstadt ◽

Ilia Tamarin ◽

...

Keyword(s):

Coronary Artery ◽

Coronary Artery Bypass Grafting ◽

Factor Viii ◽

Coronary Artery Bypass ◽

Hemophilia A ◽

Artery Bypass ◽

Bypass Grafting ◽

Severe Hemophilia ◽

Factor Viii Activity ◽

Artery Bypass Grafting

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An In Vitro Analysis of the Combination of Hemophilia A and Factor VLEIDEN

Blood ◽

10.1182/blood.v90.8.3067 ◽

1997 ◽

Vol 90 (8) ◽

pp. 3067-3072 ◽

Cited By ~ 60

Author(s):

Cornelis van ‘t Veer ◽

Neal J. Golden ◽

Michael Kalafatis ◽

Paolo Simioni ◽

Rogier M. Bertina ◽

...

Keyword(s):

Factor Viii ◽

Tissue Factor ◽

Thrombin Generation ◽

Hemophilia A ◽

Factor Viia ◽

Factor V ◽

Severe Hemophilia ◽

Factor Viii Activity ◽

Thrombin Formation

Abstract The classification of factor VIII deficiency, generally used based on plasma levels of factor VIII, consists of severe (<1% normal factor VIII activity), moderate (1% to 4% factor VIII activity), or mild (5% to 25% factor VIII activity). A recent communication described four individuals bearing identical factor VIII mutations. This resulted in a severe bleeding disorder in two patients who carried a normal factor V gene, whereas the two patients who did not display severe hemophilia were heterozygous for the factor VLEIDEN mutation, which leads to the substitution of Arg506 → Gln mutation in the factor V molecule. Based on the factor VIII level measured using factor VIII–deficient plasma, these two patients were classified as mild/moderate hemophiliacs. We studied the condition of moderate to severe hemophilia A combined with the factor VLEIDEN mutation in vitro in a reconstituted model of the tissue factor pathway to thrombin. In the model, thrombin generation was initiated by relipidated tissue factor and factor VIIa in the presence of the coagulation factors X, IX, II, V, and VIII and the inhibitors tissue factor pathway inhibitor, antithrombin-III, and protein C. At 5 pmol/L initiating factor VIIa⋅tissue factor, a 10-fold higher peak level of thrombin formation (350 nmol/L), was observed in the system in the presence of plasma levels of factor VIII compared with reactions without factor VIII. Significant increase in thrombin formation was observed at factor VIII concentrations less than 42 pmol/L (∼6% of the normal factor VIII plasma concentration). In reactions without factor VIII, in which thrombin generation was downregulated by the addition of protein C and thrombomodulin, an increase of thrombin formation was observed with the factor VLEIDEN mutation. The level of increase in thrombin generation in the hemophilia A situation was found to be dependent on the factor VLEIDEN concentration. When the factor VLEIDEN concentration was varied from 50% to 150% of the normal plasma concentration, the increase in thrombin generation ranged from threefold to sevenfold. The data suggested that the analysis of the factor V genotype should be accompanied by a quantitative analysis of the plasma factor VLEIDEN level to understand the effect of factor VLEIDEN in hemophilia A patients. The presented data support the hypothesis that the factor VLEIDEN mutation can increase thrombin formation in severe hemophilia A.

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Genetic analysis of non-severe hemophilia A phenotype with a discrepancy between one-stage and chromogenic factor VIII activity assays

Transfusion and Apheresis Science ◽

10.1016/j.transci.2021.103194 ◽

2021 ◽

pp. 103194

Author(s):

Amir Valikhani ◽

Mojgan Mirakhorly ◽

Ali Namvar ◽

Ghasem Rastegarlari ◽

Gholamreza toogeh ◽

...

Keyword(s):

Genetic Analysis ◽

Factor Viii ◽

Hemophilia A ◽

Severe Hemophilia ◽

Factor Viii Activity ◽

One Stage

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Antibody ESH4, Against the Factor VIII C2 Domain, Causes a Remote Change near the Factor IXa Active Site and Inhibition That Is Related to Membrane Composition

Blood ◽

10.1182/blood.v120.21.3355.3355 ◽

2012 ◽

Vol 120 (21) ◽

pp. 3355-3355

Author(s):

Valerie A Novakovic ◽

Junhong Lu ◽

Gary E. Gilbert

Keyword(s):

Factor Viii ◽

Active Site ◽

Hemophilia A ◽

Membrane Binding ◽

Bleeding Risk ◽

C2 Domain ◽

Membrane Composition ◽

Factor Viii Activity ◽

Factor Ixa ◽

Factor Viiia

Abstract Abstract 3355 Introduction: Development of antibodies against factor VIII is a common complication of therapy for hemophilia A and can cause acquired hemophilia A in previously normal subjects. Dominant epitopes for inhibitory antibodies reside on the C2 domain of factor VIII, which has been shown to be important for membrane binding. Although acquired hemophilia A is associated with a prolonged activated partial thromboplastin time (aPTT), the relative bleeding risk does not correlate well with factor VIII activity levels. Thus there is a need for basic insights that explain the discrepancies between factor VIII activity values and bleeding risk in these patients. mAb ESH4, directed against the factor VIII C2 domain, interferes with membrane binding and is a prototypic factor VIII inhibitor. ESH4 is a type II inhibitor, with residual factor VIII activity in the presence of saturating antibody concentrations. Thus, exploration of the inhibitory mechanism of ESH4 may offer insights into bleeding risk assessment of antibodies that inhibit phospholipid binding. Methods: Binding of fluorescein-labeled factor VIII to phospholipid membranes supported on glass microspheres was measured in the presence and absence of ESH4 using flow cytometry. The effect of ESH4 on factor VIII activity was measured using a two-stage amidolytic factor Xase assay and sonicated lipid vesicles with either low (4%) or high (15%) levels of PS. The factor Xase assay was also performed using platelets as the phospholipid source. Factor IXa, with its active site labeled using fluorescein-EGR chloromethyl ketone (Fl-EGRck), was mixed with sonicated phospholipid vesicles, factor VIIIa, and factor × and the anisotropy of the fluorescein molecule was measured to test the effect of ESH4 on the factor IXa active site. Results: Saturating concentrations of ESH4 inhibited 40% of factor VIII activity in a commercial aPTT assay. In a defined assay, inhibition of factor VIII activity was directly related to the phospholipid composition and concentration. In the presence of saturating phospholipid and factor X, ESH4 caused over 60% decrease in the Vmax for vesicles with either 4% or 15% PS. To determine the mechanism through which ESH4 inhibits membrane-bound factor VIII activity, we measured the fluorescence anisotropy of factor IXa-Fl-EGRck. ESH4 decreased anisotropy of the factor VIIIa-factor IXa-factor × complex from 0.280 ± 0.002 to 0.272 ± 0.002 on 15% PS vesicles and from 0.275 ± 0.002 to 0.262 ± 0.001 on 4% PS vesicles, indicating that ESH4 alters the Vmax through a change near the factor IXa active site, remote from the C2 domain-membrane interface. ESH4 decreased the apparent affinity 4-fold for membranes of 4% PS (KD = 4.8 ± 0.4 mM without and 21 ± 4 mM with ESH4) but only 2-fold on 15% PS vesicles (KD = 1.3 ± 0.2 mM without and 2.5 ± 0.5 mM with ESH4). Direct membrane binding studies of fluorescein-labeled factor VIII indicated a reduction in affinity and number of binding sites consistent with the results from the factor Xase assay. The apparent affinity for factor × in the presence of saturating phospholipid and ESH4 was higher on 15% PS vesicles (KM = 129 ± 18 nM) than on 4% PS vesicles (KM= 284 ± 30 nM). Together, these results indicate that ESH4 can decrease factor VIII activity through three mechanisms: (1) decreased membrane affinity (2) decreased activity of membrane-bound factor VIII and (3) differential affinity of the factor Xase complex for factor X. Because two of these mechanisms are influenced by membrane composition we asked whether the degree of inhibition by ESH4 might differ on platelets stimulated to different degrees. Platelets stimulated by thrombin express limited PS in a reversible manner while platelets stimulated by > 1 μM A23187 have complete PS exposure. ESH4 showed 80% inhibition of Xase activity on platelets stimulated with thrombin vs. 40% inhibition on platelets stimulated with A23187, similar to the aPTT assay. Conclusions: Our results indicate that ESH4 disruption of factor VIII C2 domain engagement with the membrane has a remote effect at the factor IXa active site. Inhibition of factor VIII activity by ESH4 is sensitive to membrane composition and concentration through two mechanisms. These results highlight the need to better understand how membrane binding activates the factor VIIIa-factor IXa complex and to develop clinical assays that measure factor VIII activity on clinically relevant membrane types and concentrations. Disclosures: No relevant conflicts of interest to declare.

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Population Pharmacokinetic Analysis of Recombinant Factor VIII Fc Fusion Protein in Subjects With Severe Hemophilia A: Expanded to Include Pediatric Subjects

The Journal of Clinical Pharmacology ◽

10.1002/jcph.1854 ◽

2021 ◽

Author(s):

Suresh Katragadda ◽

Srividya Neelakantan ◽

Lei Diao ◽

Nancy Wong

Keyword(s):

Fusion Protein ◽

Factor Viii ◽

Hemophilia A ◽

Population Pharmacokinetic Analysis ◽

Recombinant Factor Viii ◽

Pharmacokinetic Analysis ◽

Population Pharmacokinetic ◽

Severe Hemophilia ◽

Fc Fusion Protein

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Relationship between factor VIII activity, bleeds and individual characteristics in severe hemophilia A patients

Haematologica ◽

10.3324/haematol.2019.217133 ◽

2019 ◽

Vol 105 (5) ◽

pp. 1443-1453 ◽

Cited By ~ 3

Author(s):

João A. Abrantes ◽

Alexander Solms ◽

Dirk Garmann ◽

Elisabet I. Nielsen ◽

Siv Jönsson ◽

...

Keyword(s):

Factor Viii ◽

Hemophilia A ◽

Individual Characteristics ◽

Severe Hemophilia ◽

Factor Viii Activity

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T Lymphocyte Proliferative Responses Induced by Recombinant Factor VIII in Hemophilia A Patients with Inhibitors

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650515 ◽

1996 ◽

Vol 76 (01) ◽

pp. 017-022 ◽

Cited By ~ 27

Author(s):

Sylvia T Singer ◽

Joseph E Addiego ◽

Donald C Reason ◽

Alexander H Lucas

Keyword(s):

T Lymphocytes ◽

Factor Viii ◽

Cellular Proliferation ◽

Mononuclear Cells ◽

Hemophilia A ◽

Normal Subjects ◽

Normal Male ◽

Cell Fractionation ◽

Severe Hemophilia ◽

Human Factor Viii

SummaryIn this study we sought to determine whether factor VUI-reactive T lymphocytes were present in hemophilia A patients with inhibitor antibodies. Peripheral blood mononuclear cells (MNC) were obtained from 12 severe hemophilia A patients having high titer inhibitors, 4 severe hemophilia A patients without inhibitors and 5 normal male subjects. B cell-depleted MNC were cultured in serum-free medium in the absence or presence of 2 µg of recombinant human factor VIII (rFVIII) per ml, and cellular proliferation was assessed after 5 days of culture by measuring 3H-thymidine incorporation. rFVIII induced marked cellular proliferation in cultures of 4 of 12 inhibitor-positive hemophilia patients: fold increase over background (stimulation index, SI) of 7.8 to 23.3. The remaining 8 inhibitor-positive patients, the 4 hemophilia patients without inhibitors and the 5 normal subjects, all had lower proliferative responses to rFVIII, SI range = 1.6 to 6.0. As a group, the inhibitor-positive subjects had significantly higher proliferative responses to rFVIII than did the inhibitor-negative and normal subjects (p < 0.05 by t-test). Cell fractionation experiments showed that T lymphocytes were the rFVIII-responsive cell type, and that monocytes were required for T cell proliferation. Thus, rFVIII-reactive T lymphocytes are present in the peripheral circulation of some inhibitor-positive hemophilia A patients. These T cells may recognize FVIII in an antigen-specific manner and play a central role in the regulation of inhibitor antibody production

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