title: Helper-dependent adenoviral gene therapy mediates long-term correction of the clotting defect in the canine hemophilia A model.
abstract: BACKGROUND
  Adenoviral vector-mediated gene therapy might have potential for long-term correction of the monogenic disease hemophilia A.
  
  
  OBJECTIVE
  In this study, we tested the efficacy of administering a helper-dependent adenoviral vector (HDV) designed for maximal liver-restricted canine factor VIII (cFVIII) expression on three out-bred hemophilia A dogs.
  
  
  METHODS
  Three FVIII-deficient animals from the University of North Carolina colony were injected with 1 x 10(12) (Dog A), and 3 x 10(12) (Dog B and C) vp kg(-1) helper-dependent adenoviral vector, and we performed systematic analysis of toxicity, persistence of therapeutic gene expression, and molecular analysis of gene transfer.
  
  
  RESULTS
  We observed acute dose-dependent elevation in liver enzymes and thrombocytopenia after injection, although both were transient and resolved within 2 weeks. The whole blood clotting time (WBCT), plasma FVIII concentration, FVIII activity, and activated partial thromboplastin time in all animals improved significantly after treatment, and two animals receiving a higher dose reached near normal WBCT with low-level FVIII activity until terminal sacrifice at 3 months, and 2 years. Importantly, the treated dogs suffered no bleeding events after injection. Moreover, we observed persistent vector-specific DNA and RNA in liver tissue collected from one high-dose animal at days 18 and 79, and could not detect the formation of inhibitory antibodies.
  
  
  CONCLUSIONS
  Although vector-associated toxicity remains an obstacle, a single injection of HDV led to long-term transgene expression and vector persistence in two FVIII-deficient animals with conversion of their severe phenotype to a moderate one.
authors.affiliation: Department of Molecular and Human Genetics.
authors.forename: W M
authors.initials: WM
authors.lastname: McCORMACK
authors.affiliation: Department of Molecular and Human Genetics.|Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, TX.
authors.forename: M P
authors.initials: MP
authors.lastname: Seiler
authors.affiliation: Department of Molecular and Human Genetics.
authors.forename: T K
authors.initials: TK
authors.lastname: Bertin
authors.affiliation: Department of Molecular and Human Genetics.
authors.forename: K
authors.initials: K
authors.lastname: Ubhayakar
authors.affiliation: Department of Molecular and Human Genetics.
authors.forename: D J
authors.initials: DJ
authors.lastname: Palmer
authors.affiliation: Department of Molecular and Human Genetics.
authors.forename: P
authors.initials: P
authors.lastname: Ng
authors.affiliation: Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC.
authors.forename: T C
authors.initials: TC
authors.lastname: Nichols
authors.affiliation: Department of Molecular and Human Genetics.|The Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, USA.
authors.forename: B
authors.initials: B
authors.lastname: Lee
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D001777:Blood Coagulation; D004195:Disease Models, Animal; D004285:Dogs; D005169:Factor VIII / Q000235:genetics* / Q000378:metabolism / Q000627:therapeutic use; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000633:toxicity; D006467:Hemophilia A / Q000097:blood / Q000235:genetics / Q000628:therapy*; D008099:Liver / Q000378:metabolism; D009154:Mutation; D010314:Partial Thromboplastin Time; D014914:Whole Blood Coagulation Time
chemical_list: D005169:Factor VIII