Safety, Stability and Pharmacokinetic Properties of superFactor Va, a Novel Engineered Coagulation Factor V for Treatment of Severe Bleeding
Activated superFactor V (superFVa) is a novel engineered FV with excellent prohemostatic efficacy. SuperFVa has three APC cleavage site mutations and an interdomain disulfide bond. Stability, pharmacokinetics, and immunogenic and thrombogenic potential are reported here.
Stability and circulating half-life were determined after incubation in buffer and human plasma, and after injection into FVIII-deficient mice. Immunogenicity potential was assessed by B- and T-cell specific epitope prediction and structural analysis using surface area and atomic depth computation. Thrombogenic potential was determined by quantification of lung fibrin deposition in wild-type mice after intravenous injection of superFVa (200 U/kg), recombinant human (rh) Tissue Factor (0.4–16 pmol/kg), rhFVIIa (3 mg/kg) or saline.
FVa retained full activity over 30 h in buffer, the functional half-life in human plasma was 4.9 h, and circulating half-life in FVIII-deficient mice was ~30 min. Predicted immunogenicity was not increased compared to human FV. While rh Tissue Factor, the positive control, resulted in pronounced lung fibrin depositions (mean 121 μg/mL), superFVa did not (6.7 μg/mL), and results were comparable to fibrin depositions with rhFVIIa (7.6 μg/mL) or saline (5.6 μg/mL).
FVa has an appropriate safety and stability profile for further preclinical development as a prohemostatic against severe bleeding.
KEY WORDSbleeding factor V hemophilia hemostasis immunogenicity thrombogenicity
activated protein C
direct oral anticoagulant
endogenous thrombin potential
activated factor V
factor V deficient plasma
recombinant human tissue factor
activated super factor V
ACKNOWLEDGMENTS AND DISCLOSURES
This work was funded by grant support from an Early Career Development Award from Bayer Hemophilia (AvD), by National Institutes of Health grants HL104165 (LOM) and HL03195 and HL052246 (JHG).
Compliance with Ethical Standards
AvD has received honoraria for participating in scientific advisory board panels, consulting, and speaking engagements for Baxalta, Pfizer, Biogen, CSL-Behring, Novo Nordisk, and Grifols. LOM has received research funding and honoraria for participating in scientific advisory board panels for Bayer. UCSD and TSRI hold intellectual property rights related to superFVa on which AvD, AJG, JHG, and LOM are listed as inventors. AvD, AJG, and LOM are founders of Hematherix LLC., a biotech company that is developing superFVa therapy for bleeding complications. AvD and LOM are members of the Board of Directors of Hematherix LLC.
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