title: Efficacy and safety of long-term prophylaxis in severe hemophilia A dogs following liver gene therapy using AAV vectors.
abstract: Developing adeno-associated viral (AAV)-mediated gene therapy for hemophilia A (HA) has been challenging due to the large size of the factor VIII (FVIII) complementary DNA and the concern for the development of inhibitory antibodies to FVIII in HA patients. Here, we perform a systematic study in HA dogs by delivering a canine FVIII (cFVIII) transgene either as a single chain or two chains in an AAV vector. An optimized cFVIII single chain delivered using AAV serotype 8 (AAV8) by peripheral vein injection resulted in a dose-response with sustained expression of FVIII up to 7% (n = 4). Five HA dogs administered two-chain delivery using either AAV8 or AAV9 via the portal vein expressed long-term, vector dose-dependent levels of FVIII activity (up to 10%). In the two-chain approach, circulating cFVIII antigen levels were more than fivefold higher than activity. Notably, no long-term immune response to FVIII was observed in any of the dogs (1/9 dogs had a transient inhibitor). Long-term follow-up of the dogs showed a remarkable reduction (>90%) of bleeding episodes in a combined total of 24 years of observation. These data demonstrate that both approaches are safe and achieve dose-dependent therapeutic levels of FVIII expression, which supports translational studies of AAV-mediated delivery for HA.
authors.affiliation: Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA. dsabatin@mail.med.upenn.edu
authors.forename: Denise E
authors.initials: DE
authors.lastname: Sabatino
authors.forename: Amy M
authors.initials: AM
authors.lastname: Lange
authors.forename: Ekaterina S
authors.initials: ES
authors.lastname: Altynova
authors.forename: Rita
authors.initials: R
authors.lastname: Sarkar
authors.forename: Shangzhen
authors.initials: S
authors.lastname: Zhou
authors.forename: Elizabeth P
authors.initials: EP
authors.lastname: Merricks
authors.forename: Helen G
authors.initials: HG
authors.lastname: Franck
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Nichols
authors.forename: Valder R
authors.initials: VR
authors.lastname: Arruda
authors.forename: Haig H
authors.initials: HH
authors.lastname: Kazazian
mesh_terms: D000818:Animals; D000229:Dependovirus / Q000235:genetics; D004195:Disease Models, Animal; D004285:Dogs; D005169:Factor VIII / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D023061:Gene Order; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics; D006467:Hemophilia A / Q000276:immunology / Q000517:prevention & control / Q000628:therapy; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010641:Phenotype; D016896:Treatment Outcome
chemical_list: D005169:Factor VIII