title: AAV-mediated factor IX gene transfer to skeletal muscle in patients with severe hemophilia B.
abstract: Hemophilia B is an X-linked coagulopathy caused by absence of functional coagulation factor IX (F.IX). Previously, we established an experimental basis for gene transfer as a method of treating the disease in mice and hemophilic dogs through intramuscular injection of a recombinant adeno-associated viral (rAAV) vector expressing F.IX. In this study we investigated the safety of this approach in patients with hemophilia B. In an open-label dose-escalation study, adult men with severe hemophilia B (F.IX < 1%) due to a missense mutation were injected at multiple intramuscular sites with an rAAV vector. At doses ranging from 2 x 10(11) vector genomes (vg)/kg to 1.8 x 10(12) vg/kg, there was no evidence of local or systemic toxicity up to 40 months after injection. Muscle biopsies of injection sites performed 2 to 10 months after vector administration confirmed gene transfer as evidenced by Southern blot and transgene expression as evidenced by immunohistochemical staining. Pre-existing high-titer antibodies to AAV did not prevent gene transfer or expression. Despite strong evidence for gene transfer and expression, circulating levels of F.IX were in all cases less than 2% and most were less than 1%. Although more extensive transduction of muscle fibers will be required to develop a therapy that reliably raises circulating levels to more than 1% in all subjects, these results of the first parenteral administration of rAAV demonstrate that administration of AAV vector by the intramuscular route is safe at the doses tested and effects gene transfer and expression in humans in a manner similar to that seen in animals.
authors.affiliation: Department of Pediatrics, University of Pennsylvania and the Children's Hospital of Philadelphia, PA, 19104, USA. manno@email.chop.edu
authors.forename: Catherine S
authors.initials: CS
authors.lastname: Manno
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Chew
authors.forename: Sylvia
authors.initials: S
authors.lastname: Hutchison
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Larson
authors.forename: Roland W
authors.initials: RW
authors.lastname: Herzog
authors.forename: Valder R
authors.initials: VR
authors.lastname: Arruda
authors.forename: Shing Jen
authors.initials: SJ
authors.lastname: Tai
authors.forename: Margaret V
authors.initials: MV
authors.lastname: Ragni
authors.forename: Arthur
authors.initials: A
authors.lastname: Thompson
authors.forename: Margareth
authors.initials: M
authors.lastname: Ozelo
authors.forename: Linda B
authors.initials: LB
authors.lastname: Couto
authors.forename: Debra G B
authors.initials: DG
authors.lastname: Leonard
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Johnson
authors.forename: Alan
authors.initials: A
authors.lastname: McClelland
authors.forename: Ciaran
authors.initials: C
authors.lastname: Scallan
authors.forename: Erik
authors.initials: E
authors.lastname: Skarsgard
authors.forename: Alan W
authors.initials: AW
authors.lastname: Flake
authors.forename: Mark A
authors.initials: MA
authors.lastname: Kay
authors.forename: Katherine A
authors.initials: KA
authors.lastname: High
authors.forename: Bertil
authors.initials: B
authors.lastname: Glader
mesh_terms: D000328:Adult; D000368:Aged; D019943:Amino Acid Substitution; D001706:Biopsy; D003131:Combined Modality Therapy; D000229:Dependovirus / Q000235:genetics*; D005164:Factor IX / Q000032:analysis / Q000235:genetics* / Q000627:therapeutic use; D005240:Feasibility Studies; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000008:administration & dosage / Q000627:therapeutic use*; D015658:HIV Infections / Q000150:complications; D002836:Hemophilia B / Q000150:complications / Q000235:genetics / Q000628:therapy*; D006525:Hepatitis, Viral, Human / Q000150:complications; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D020125:Mutation, Missense; D011993:Recombinant Fusion Proteins / Q000032:analysis; D012449:Safety
chemical_list: D011993:Recombinant Fusion Proteins; D005164:Factor IX