2011•New England Journal of MedicineOpen access
Adenovirus-Associated Virus Vector–Mediated Gene Transfer in Hemophilia B
Amit C. Nathwani, Edward G. D. Tuddenham, Savita Rangarajan, Cecilia Rosales, Jenny McIntosh, David C. Linch, Pratima Chowdary, Anne F. Riddell, Arnulfo Pie, Chris F. Harrington, James P. O’Beirne, Keith J. Smith, John Pasi, Bertil E. Glader, Pradip K. Rustagi, Catherine Y. Ng, Mark A. Kay, Junfang Zhou, Yunyu Spence, Christopher L. Morton, James A. Allay, John B. Coleman, Susan Sleep, John M. Cunningham, Deo Kumar Srivastava, Etiena Basner‐Tschakarjan, Federico Mingozzi, Katherine A. High, John T. Gray, Ulrike M. Reiss, Arthur W. Nienhuis, Andrew M. Davidoff
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Abstract
BACKGROUND: Hemophilia B, an X-linked disorder, is ideally suited for gene therapy. We investigated the use of a new gene therapy in patients with the disorder. METHODS: We infused a single dose of a serotype-8-pseudotyped, self-complementary adenovirus-associated virus (AAV) vector expressing a codon-optimized human factor IX (FIX) transgene (scAAV2/8-LP1-hFIXco) in a peripheral vein in six patients with severe hemophilia B (FIX activity, <1% of normal values). Study participants were enrolled sequentially in one of three cohorts (given a high, intermediate, or low dose of vector), with two participants in each group. Vector was administered without immunosuppressive therapy, and participants were followed for 6 to 16 months. RESULTS: AAV-mediated expression of FIX at 2 to 11% of normal levels was observed in all participants. Four of the six discontinued FIX prophylaxis and remained free of spontaneous hemorrhage; in the other two, the interval between prophylactic injections was increased. Of the two participants who received the high dose of vector, one had a transient, asymptomatic elevation of serum aminotransferase levels, which was associated with the detection of AAV8-capsid-specific T cells in the peripheral blood; the other had a slight increase in liver-enzyme levels, the cause of which was less clear. Each of these two participants received a short course of glucocorticoid therapy, which rapidly normalized aminotransferase levels and maintained FIX levels in the range of 3 to 11% of normal values. CONCLUSIONS: Peripheral-vein infusion of scAAV2/8-LP1-hFIXco resulted in FIX transgene expression at levels sufficient to improve the bleeding phenotype, with few side effects. Although immune-mediated clearance of AAV-transduced hepatocytes remains a concern, this process may be controlled with a short course of glucocorticoids without loss of transgene expression. (Funded by the Medical Research Council and others; ClinicalTrials.gov number, NCT00979238.).
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