Therapeutic levels of FVIII following a single peripheral vein administration of rAAV vector encoding a novel human factor VIII variant

Blood. 2013 Apr 25;121(17):3335-44. doi: 10.1182/blood-2012-10-462200. Epub 2013 Feb 20.


Recombinant adeno-associated virus (rAAV) vectors encoding human factor VIII (hFVIII) were systematically evaluated for hemophilia A (HA) gene therapy. A 5.7-kb rAAV-expression cassette (rAAV-HLP-codop-hFVIII-N6) containing a codon-optimized hFVIII cDNA in which a 226 amino acid (aa) B-domain spacer replaced the entire B domain and a hybrid liver-specific promoter (HLP) mediated 10-fold higher hFVIII levels in mice compared with non-codon-optimized variants. A further twofold improvement in potency was achieved by replacing the 226-aa N6 spacer with a novel 17-aa peptide (V3) in which 6 glycosylation triplets from the B domain were juxtaposed. The resulting 5.2-kb rAAV-HLP-codop-hFVIII-V3 cassette was more efficiently packaged within AAV virions and mediated supraphysiologic hFVIII expression (732 ± 162% of normal) in HA knock-out mice following administration of 2 × 10(12) vector genomes/kg, a vector dose shown to be safe in subjects with hemophilia B. Stable hFVIII expression at 15 ± 4% of normal was observed at this dose in a nonhuman primate. hFVIII expression above 100% was observed in 3 macaques that received a higher dose of either this vector or the N6 variant. These animals developed neutralizing anti-FVIII antibodies that were abrogated with transient immunosuppression. Therefore, rAAV-HLP-codop-hFVIII-V3 substantially improves the prospects of effective HA gene therapy.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Dependovirus / genetics*
  • Factor VIII / genetics
  • Factor VIII / immunology
  • Factor VIII / pharmacology*
  • Genetic Therapy*
  • Genetic Variation / genetics*
  • Genetic Vectors / administration & dosage*
  • Glycosylation
  • Hemophilia A / genetics
  • Hemophilia A / therapy*
  • Humans
  • Immune Tolerance
  • Liver / metabolism
  • Macaca mulatta
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Promoter Regions, Genetic / genetics


  • Peptide Fragments
  • F8 protein, human
  • Factor VIII