Prolonged activity of a recombinant factor VIII-Fc fusion protein in hemophilia A mice and dogs

Abstract Despite proven benefits, prophylactic treatment for hemophilia A is hampered by the short half-life of factor VIII. A recombinant factor VIII-Fc fusion protein (rFVIIIFc) was constructed to determine the potential for reduced frequency of dosing. rFVIIIFc has an ∼ 2-fold longer half-life than rFVIII in hemophilia A (HemA) mice and dogs. The extension of rFVIIIFc half-life requires interaction of Fc with the neonatal Fc receptor (FcRn). In FcRn knockout mice, the extension of rFVIIIFc half-life is abrogated, and is restored in human FcRn transgenic mice. The Fc fusion has no impact on FVIII-specific activity. rFVIIIFc has comparable acute efficacy as rFVIII in treating tail clip injury in HemA mice, and fully corrects whole blood clotting time (WBCT) in HemA dogs immediately after dosing. Furthermore, consistent with prolonged half-life, rFVIIIFc shows 2-fold longer prophylactic efficacy in protecting HemA mice from tail vein transection bleeding induced 24-48 hours after dosing. In HemA dogs, rFVIIIFc also sustains partial correction of WBCT 1.5- to 2-fold longer than rFVIII. rFVIIIFc was well tolerated in both species. Thus, the rescue of FVIII by Fc fusion to provide prolonged protection presents a novel pathway for FVIII catabolism, and warrants further investigation.

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Development of a Pegylated Dimeric Recombinant Factor VIII-Fc Fusion Protein for the Treatment for Hemophilia a Patients

Blood ◽

10.1182/blood-2018-99-112030 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 3783-3783

Author(s):

Bin Liu ◽

Xiaoshan Wang ◽

Xueqin Li ◽

Haixia Yan ◽

Shuya Wang ◽

...

Keyword(s):

Fusion Protein ◽

Factor Viii ◽

Treatment Option ◽

Half Life ◽

Hemophilia A ◽

Binding Activity ◽

Recombinant Factor Viii ◽

Fc Fusion Protein ◽

In Vivo Tests

Abstract Hemophilia A is a hereditary bleeding disorder resulting from reduced factor FVIII activity. It occurred in 1/5000 male. Currently, the treatment option is with the factor FVIII replacement therapy. A long-acting recombinant monomeric FVIII-Fc fusion protein product (Eloctate®) has been approved in 2014 by the US FDA, it requires to infuse the drug for every 3 days or twice a week. There is a clinical need to develop longer half-life product to extend the treatment option to once a week infuse for hemophilia A patients. Recently, we have developed a dimeric recombinant factor VIII-Fc (drFVIII-Fc) fusion protein therapeutic candidate, which is entering the clinical development in China. To generate a longer half-life recombinant FVIII product, we have developed a PEGylation method to PEGylated this drFVIII-Fc fusion protein to PEGdrFVIII-Fc. We have analyzed and characterized the fusion protein by various analytic methods, as well as in vivo animal tests. It was shown that PEGdrFVIII-Fc fusion protein has been modified with about five Y type of 40kd PEG; the remaining activity is around 700 IU/mg, and the in vivo tests in cynomolgus monkey demonstrated that the fusion protein has a half-life of about 37 hours. The data also showed that there was no detectable affinity binding activity of vWF to a PEGdrFVIII-Fc fusion protein, as compared with the binding activity of 5.16X10-4M for the molecule of a drFVIII-Fc fusion protein. In conclusion, we are able to generate a PEGylated form of a drFVIII-Fc molecule with the relevant specific activity and has been shown the molecule with the prolonger half-life in the in vivo tests. The further biochemical analysis demonstrated PEGdrFVIII-Fc fusion protein with no detectable vWF binding activity, which might explain why its half-life is longer than vWF's ~15hours half-life in vivo. This molecule is likely to be used as a once-weekly treatment option for hemophilia A patients. Currently, we are in the development stage of an IND filing in China. Disclosures No relevant conflicts of interest to declare.

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Phase 3 study of recombinant factor VIII Fc fusion protein in severe hemophilia A

Blood ◽

10.1182/blood-2013-10-529974 ◽

2014 ◽

Vol 123 (3) ◽

pp. 317-325 ◽

Cited By ~ 237

Author(s):

Johnny Mahlangu ◽

Jerry S. Powell ◽

Margaret V. Ragni ◽

Pratima Chowdary ◽

Neil C. Josephson ◽

...

Keyword(s):

Fusion Protein ◽

Factor Viii ◽

Half Life ◽

Hemophilia A ◽

Recombinant Factor Viii ◽

Severe Hemophilia ◽

Phase 3 ◽

Injection Frequency ◽

Key Points ◽

Fc Fusion Protein

Key Points A novel recombinant factor VIII with prolonged half-life, rFVIIIFc, was developed to reduce prophylactic injection frequency. rFVIIIFc was well-tolerated in patients with severe hemophilia A, and resulted in low bleeding rates when dosed 1 to 2 times per week.

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Factor VIII-Fc Fusion Protein Shows Extended Half-Life and Hemostatic Activity in Hemophilia A Dogs.

Blood ◽

10.1182/blood.v114.22.545.545 ◽

2009 ◽

Vol 114 (22) ◽

pp. 545-545 ◽

Cited By ~ 2

Author(s):

Jennifer A Dumont ◽

George D Kamphaus ◽

Cara Fraley ◽

Tamera Ashworth ◽

Helen Franck ◽

...

Keyword(s):

Fusion Protein ◽

Factor Viii ◽

Half Life ◽

Hemophilia A ◽

Specific Activity ◽

Clinical Signs ◽

Severe Form ◽

Activity Data ◽

Hemostatic Activity ◽

Elisa Data

Abstract Abstract 545 A recombinant B-domain-deleted factor VIII-Fc (rFVIIIFc) fusion protein was created as an approach to extend the half-life of FVIII. The pharmacokinetics and pharmacodynamics of rFVIIIFc were evaluated in the Chapel Hill colony of hemophilia A dogs. These dogs have a severe hemophilic phenotype comparable to the severe form of human disease with F.VIII < 1%. A single intravenous dose (125 IU/kg) was administered to four dogs and immediately corrected the clotting to normal as measured by whole blood clotting time (WBCT) and aPTT. The WBCT remained below 20 min, the time consistent with FVIII:C > 1%, through approximately 96 h. The range of WBCT in our normal dogs is 8 to 12 min. The concentration of rFVIIIFc in the plasma was measured by ELISA and the terminal half-life was 15.7 ± 1.7 hr. Similar results were obtained when rFVIIIFc was measured using a FVIII-specific chromogenic activity assay (half-life was 15.4 ± 0.3 hr). The concentration vs. time curves were similar using both methods. The activity data were converted to ng/mL using the specific activity of the test article that was used to dose the animals, and these data correlated well with the ELISA data, thus demonstrating that the protein that was measured by ELISA was fully active. Two of the dogs also received a single dose of recombinant B-domain deleted FVIII (rBDD-FVIII, ReFacto®), 114 IU/kg for one dog and 120 IU/kg rBDD-FVIII for the other, and then received rFVIIIFc (125 IU/kg) 72 hr later in a cross over design. Clotting was corrected to normal immediately after dosing with both rBDD-FVIII and rFVIIIFc (determined by WBCT and clotting activity measured using an aPTT assay). However, the WBCT normalization after rFVIIIFc lasted for approximately twice as long compared to rBDD-FVIII and the half-lives determined from the ELISA data for FVIIIFc (15.7 ± 1.7 hr) were twice those determined for rBDD-FVIII (7.0 hr and 6.7 hr). No adverse clinical signs were detected with any of the infusions. Therefore construction of an Fc fusion of FVIII produces a molecule with a defined mechanism of action that has an increased half life and the potential to provide prolonged protection from bleeding. Disclosures: Dumont: Biogen Idec (Syntonix Subsidiary): Employment. Kamphaus:Biogen Idec (Syntonix Subsidiary): Employment. Fraley:Biogen Idec/Syntonix Subsidiary: Employment. Ashworth:Biogen Idec (Syntonix Subsidiary): Employment. Bitonti:Biogen Idec/Syntonix Subsidiary: Employment.

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Faculty Opinions recommendation of Safety and prolonged activity of recombinant factor VIII Fc fusion protein in hemophilia A patients.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.720026512.793527664 ◽

2017 ◽

Author(s):

Chava Kimchi-Sarfaty

Keyword(s):

Fusion Protein ◽

Factor Viii ◽

Hemophilia A ◽

Recombinant Factor Viii ◽

Fc Fusion Protein

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A Novel, Enriched Population Pharmacokinetic Model for Recombinant Factor VIII-Fc Fusion Protein Concentrate in Hemophilia A Patients

Thrombosis and Haemostasis ◽

10.1055/s-0040-1709522 ◽

2020 ◽

Vol 120 (05) ◽

pp. 747-757

Author(s):

Laura H. Bukkems ◽

Jessica M. Heijdra ◽

Mary Mathias ◽

Peter W. Collins ◽

Charles R. M. Hay ◽

...

Keyword(s):

Fusion Protein ◽

Factor Viii ◽

Clinical Data ◽

Hemophilia A ◽

Clinical Trial Data ◽

Recombinant Factor Viii ◽

Percentage Error ◽

Population Pharmacokinetic ◽

Population Pk ◽

Fc Fusion Protein

Abstract Background The currently published population pharmacokinetic (PK) models used for PK-guided dosing in hemophilia patients are based on clinical trial data and usually not externally validated in clinical practice. The aim of this study was to validate a published model for recombinant factor VIII-Fc fusion protein (rFVIII-Fc) concentrate and to develop an enriched model using independently collected clinical data if required. Methods Clinical data from hemophilia A patients treated with rFVIII-Fc concentrate (Elocta) participating in the United Kingdom Extended Half-Life Outcomes Registry were collected. The predictive performance of the published model was assessed using mean percentage error (bias) and mean absolute percentage error (inaccuracy). An extended population PK model was developed using nonlinear mixed-effects modeling (NONMEM). Results A total of 43 hemophilia A patients (FVIII ≤ 2 IU/dL), aged 5 to 70 years, were included. The prior model was able to predict the collected 244 rFVIII-Fc levels without significant bias (–1.0%, 95% CI: –9.4 to 7.3%) and with acceptable accuracy (12.9%). However, clearance and central distribution volume were under predicted in patients <12 years, which was expected as this age group was not represented in the previous model population. An enriched population PK model was constructed, which was able to successfully characterize PK profiles of younger children. Conclusion We concluded that the existing rFVIII-Fc population PK model is valid for patients ≥ 12 years. However, it is not reliable in younger patients. Our alternative model, constructed from real world patient data including children, allows for better description of patients ≥5 years.

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