title: Bioengineered coagulation factor VIII enables long-term correction of murine hemophilia A following liver-directed adeno-associated viral vector delivery.
abstract: Clinical data support the feasibility and safety of adeno-associated viral (AAV) vectors in gene therapy applications. Despite several clinical trials of AAV-based gene transfer for hemophilia B, a unique set of obstacles impede the development of a similar approach for hemophilia A. These include (i) the size of the factor VIII (fVIII) transgene, (ii) humoral immune responses to fVIII, (iii) inefficient biosynthesis of human fVIII, and (iv) AAV vector immunity. Through bioengineering approaches, a novel fVIII molecule, designated ET3, was developed and shown to improve biosynthetic efficiency 10- to 100-fold. In this study, the utility of ET3 was assessed in the context of liver-directed, AAV-mediated gene transfer into hemophilia A mice. Due to the large size of the expression cassette, AAV-ET3 genomes packaged into viral particles as partial genome fragments. Despite this potential limitation, a single peripheral vein administration of AAV-ET3 into immune-competent hemophilia A mice resulted in correction of the fVIII deficiency at lower vector doses than previously reported for similarly oversized AAV-fVIII vectors. Therefore, ET3 appears to improve vector potency and mitigate at least one of the critical barriers to AAV-based clinical gene therapy for hemophilia A.
authors.affiliation: Graduate Program in Molecular and Systems Pharmacology, Laney Graduate School, Emory University , Atlanta, Georgia, USA.
authors.forename: Harrison C
authors.initials: HC
authors.lastname: Brown
authors.affiliation: Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia , Philadelphia, Pennsylvania, USA ; Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania, USA.
authors.forename: J Fraser
authors.initials: JF
authors.lastname: Wright
authors.affiliation: Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia , Philadelphia, Pennsylvania, USA.
authors.forename: Shangzhen
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Graduate Program in Molecular and Systems Pharmacology, Laney Graduate School, Emory University , Atlanta, Georgia, USA.
authors.forename: Allison M
authors.initials: AM
authors.lastname: Lytle
authors.affiliation: Department of Pediatrics, Aflac Cancer and Blood Disorders Center, Emory University School of Medicine , Atlanta, Georgia, USA.
authors.forename: Jordan E
authors.initials: JE
authors.lastname: Shields
authors.affiliation: Department of Pediatrics, Aflac Cancer and Blood Disorders Center, Emory University School of Medicine , Atlanta, Georgia, USA.
authors.forename: H Trent
authors.initials: HT
authors.lastname: Spencer
authors.affiliation: Department of Pediatrics, Aflac Cancer and Blood Disorders Center, Emory University School of Medicine , Atlanta, Georgia, USA.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Doering