Efficient induction of immune tolerance to coagulation factor IX following direct intramuscular gene transfer |
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Authors: | E F COHN J ZHUO M E KELLY H J CHAO |
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Institution: | Division of Hematology/Oncology, Department of Medicine, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA. |
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Abstract: | BACKGROUND: The formation of inhibitory anti-factor IX (anti-FIX) antibodies is a major complication of FIX protein replacement-based treatment for hemophilia B. It is difficult to treat patients with anti-FIX antibodies. Gene therapy is emerging as a potentially effective treatment for hemophilia. Direct i.m. injection of adeno-associated virus (AAV) is a safe and efficient procedure for hemophilia B gene therapy. However, the development of anti-FIX antibodies following i.m. of AAV may impede its application to patients. OBJECTIVE: We aimed to investigate induction of immune tolerance to human FIX (hFIX) by i.m. of AAV1, further validating i.m. of AAV1 for hemophilia B gene therapy. METHODS AND RESULTS: Cohorts of hemostatically normal and hemophilia B mice with diverse genetic and MHC backgrounds received i.m. of AAV-hFIX. Human FIX antigen and anti-hFIX antibodies were examined. I.m. of 1 x 10(11) vector genomes (VG) of AAV2 elicits formation of anti-hFIX antibodies comparable to those by hFIX protein replacement. I.m. of 1 x 10(11) VG of AAV1 results in expression of therapeutic levels of hFIX (up to 950 ng mL(-1), mean = 772 ng mL(-1), SEM +/- 35.7) and hFIX-specific immune tolerance in C57BL/6 mice. CONCLUSIONS: A single i.m. of AAV1 can result in efficient expression of therapeutic levels of hFIX and induction of hFIX tolerance in hemostatically normal and hemophilic B mice. Our results substantiate the prospect of i.m. of AAV1 for hemophilia B gene therapy and FIX tolerance induction. |
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Keywords: | adeno-associated virus factor IX gene therapy hemophilia B immune tolerance |
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