Successful Hemophilia B Gene Therapy In Dogs May Justify Human E...( CHAPEL HILL - Using gene ther...)

CHAPEL HILL - Using gene therapy on experimental animals, researchers at the University of North Carolina at Chapel Hill and elsewhere have partially corrected the protein deficiency responsible for hemophilia B. The inherited illness, also known as Christmas disease, causes victims to bleed spontaneously, live severely restricted lives and often die prematurely.

Tests have shown that a unique strain of North Carolina hemophiliac dogs injected with corrected genes produced the blood clotting protein known as factor IX and are continuing to produce it steadily more than a year and a half after treatment, scientists say. Not making the clotting factor is what causes people and animals with the condition to bleed.

"The correction is modest, about 1 percent, but we believe that's enough to justify consideration of clinical trials in humans," said Dr. Timothy C. Nichols, associate professor of medicine and pathology at the UNC-CH School of Medicine. "This level of correction in humans could be enough to improve certain people with severe hemophilia, who bleed spontaneously, to the point where they would only bleed when injured. That would be a major improvement."

Two reports on the research appear in the Jan. 5 issue of Nature Medicine. Besides UNC-CH, other institutions involved include the universities of Pennsylvania and Washington at Seattle, Stanford University and biotechnology companies Avigen Inc. and Cell Genesys Inc. of Alameda and Foster City, Calif., respectively.

The dogs, which inherit hemophilia naturally just as humans do and have been bred for a half century at UNC-CH's Frances Owen Blood Research Laboratory, showed a dose response, Nichols said. That is, the more corrected gene they received, the more strongly their bodies responded. They tolerated the treatment and replacement therapy well.

"This dose response should identify the appropriate initial dose for use in humans," he
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Contact: David Williamson
David_Williamson@unc.edu
919-962-8596
University of North Carolina at Chapel Hill
4-Jan-1999