Browsing by Author "Brown, Harrison C."

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    Coagulation factor IX gene transfer to non-human primates using engineered AAV3 capsid and hepatic optimized expression cassette
    (Elsevier, 2021-08-26) Kumar, Sandeep R. P.; Xie, Jun; Hu, Shilang; Ko, Jihye; Huang, Qifeng; Brown, Harrison C.; Srivastava, Alok; Markusic, David M.; Doering, Christopher B.; Spencer, H. Trent; Srivastava, Arun; Gao, Guangping; Herzog, Roland W.; Pediatrics, School of Medicine
    Hepatic gene transfer with adeno-associated viral (AAV) vectors shows much promise for the treatment of the X-linked bleeding disorder hemophilia B in multiple clinical trials. In an effort to further innovate this approach and to introduce alternative vector designs with potentially superior features into clinical development, we recently built a vector platform based on AAV serotype 3 because of its superior tropism for human hepatocytes. A vector genome with serotype-matched inverted terminal repeats expressing hyperactive human coagulation factor IX (FIX)-Padua was designed for clinical use that is optimized for translation using hepatocyte-specific codon-usage bias and is depleted of immune stimulatory CpG motifs. Here, this vector genome was packaged into AAV3 (T492V + S663V) capsid for hepatic gene transfer in non-human primates. FIX activity within or near the normal range was obtained at a low vector dose of 5 × 1011 vector genomes/kg. Pre-existing neutralizing antibodies, however, completely or partially blocked hepatic gene transfer at that dose. No CD8+ T cell response against capsid was observed. Antibodies against the human FIX transgene product formed at a 10-fold higher vector dose, albeit hepatic gene transfer was remarkably consistent, and sustained FIX activity in the normal range was nonetheless achieved in two of three animals for the 3-month duration of the study. These results support the use of this vector at low vector doses for gene therapy of hemophilia B in humans.
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    Development of a Clinical Candidate AAV3 Vector for Gene Therapy of Hemophilia B
    (Mary Ann Liebert, Inc., 2020-10) Brown, Harrison C.; Doering, Christopher B.; Herzog, Roland W.; Ling, Chen; Markusic, David M.; Spencer, H. Trent; Srivastava, Alok; Srivastava, Arun; Pediatrics, School of Medicine
    Although recombinant adeno-associated virus serotype 8 (AAV8) and serotype 5 (AAV5) vectors have shown efficacy in Phase 1 clinical trials for gene therapy of hemophilia B, it has become increasingly clear that these serotypes are not optimal for transducing primary human hepatocytes. We have previously reported that among the 10 most commonly used AAV serotypes, AAV serotype 3 (AAV3) vectors are the most efficient in transducing primary human hepatocytes in vitro as well as in "humanized" mice in vivo, and suggested that AAV3 vectors expressing human coagulation factor IX (hFIX) may be a more efficient alternative for clinical gene therapy of hemophilia B. In the present study, we extended these findings to develop an AAV3 vector incorporating a compact yet powerful liver-directed promoter as well as optimized hFIX cDNA sequence inserted between two AAV3 inverted terminal repeats. When packaged into an AAV3 capsid, this vector yields therapeutic levels of hFIX in hemophilia B and in "humanized" mice in vivo. Together, these studies have resulted in an AAV3 vector predicted to achieve clinical efficacy at reduced vector doses, without the need for immune-suppression, for clinical gene therapy of hemophilia B.