December 2011
The first unequivocal evidence of success in gene therapy for hemophilia B was published online Saturday in the New England Journal of Medicine. Six patients with severe hemophilia B responded to injections of a normal factor IX gene. The first patient treated with a low dose injection has maintained levels of 2% for more than 16 months while another patient receiving the highest dose maintained levels that fluctuated between 8% and 12% for 20 weeks. All six patients showed benefit from the factor IX gene administration.
According to the researchers, "this study documents a critical step toward [eliminating the need for long-term intravenous infusions] and shows that sustained therapeutic expression of a transferred factor IX gene can be achieved in humans.” The study concluded that “this gene-therapy approach, even with the associated risk of transient hepatic dysfunction, has the potential to convert the severe bleeding phenotype into a mild form of the disease or to reverse it entirely.”
The World Federation of Hemophilia has been an early supporter of gene therapy, including this trial. "We support clinicians and researchers working in the field to achieve this goal,” said WFH president Mark W. Skinner. "We are most grateful to the researchers and to the patients who have participated in clinical trials.”
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