Program: Oral and Poster Abstracts
Type: Oral
Session: 801. Gene Therapy and Transfer: Gene Therapy for Hemoglobinopathies and Inherited Bleeding Disorders
Transformed and primary human hepatocytes transduced in vitro with AAV2/6 encoding human albumin ZFNs and a promoterless hF9 transgene were shown to secrete hFIX. Extensive molecular analyses demonstrated that this was due to targeted integration of the hF9 transgene at the albumin locus and splicing of this gene into the albumin transcript. By employing AAV2/6 delivery of murine-specific ZFNs in vivo, stable levels of hFIX were observed in blood of mice injected with the albumin ZFNs and hF9 transgene donor. C57BL/6 mice were administered vehicle (n=20) or AAV2/6 vectors (n=25) encoding mouse surrogate reagents at 1.0 x1013 vector genome (vg)/kg via tail vein injection. ELISA analysis of plasma hFIX in the treated mice showed peak levels of 50-1053 ng/mL that were sustained for the duration of the 6-month study. Analysis of FIX activity from mouse plasma confirmed bioactivity commensurate with expression levels. Next, we report the feasibility of this approach in non-human primates (NHPs), showing that a single intravenous co-infusion of AAV2/6 vectors encoding the NHP targeted albumin-specific ZFNs and a human F9 donor at 1.2x1013 vg/kg (n=5/group) resulted in >50 ng/mL (>1% of normal) in this large animal model. The use of higher AAV2/6 doses (up to 1.5x1014 vg/kg) yielded plasma hFIX levels up to 1000 ng/ml (or 20% of normal) in several animals and up to 2000 ng/ml (or 50% of normal) in a single animal, for the duration of the study (3 months). The treatment was well tolerated in mice and NHPs, with no significant toxicological findings related to AAV2/6 ZFN + donor treatment in either species at therapeutic doses. Together, these data support a clinical trial to determine if a single co-administration of ZFN and donor AAV vectors is sufficient to enable therapeutic and potentially lifelong production of the clotting factor for the treatment of Hemophilia B.
Disclosures: Wechsler: Sangamo BioSciences: Employment . Meyer: Sangamo Biosciences Inc: Employment . Spratt: Sangamo Biosciences Inc: Employment . Greengard: Sangamo Biosciences Inc: Employment . Santiago: Sangamo Biosciences Inc: Employment . Sproul: Sangamo Biosciences Inc: Employment . Surosky: Sangamo Biosciences Inc: Employment . Paschon: Sangamo Biosciences Inc: Employment . Dubois-Stringfellow: Sangamo Biosciences Inc: Employment . Ando: Sangamo Biosciences Inc: Employment . Nichol: Sangamo Biosciences Inc: Employment . Rebar: Sangamo BioSciences: Employment . Holmes: Sangamo BioSciences: Employment .
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