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Progress Continues in Hemophilia B Gene Therapy Study

January 1, 2013

In December 2012, investigators from the Memphis, TN-based St. Jude Children's Research Hospital provided the latest progress in a breakthrough hemophilia B gene therapy study that began in 2010. A single intravenous injection of this gene therapy into patients with hemophilia B activates the production of small amounts of factor IX (FIX), the deficient protein. The report was presented at the 54th Annual Meeting and Exposition of the American Society of Hematology (ASH), held December 8-11, 2012, in Atlanta, GA.

Researchers from St. Jude and the University College London (UCL) Cancer Institute have successfully used adeno-associated viruses (AAVs) as delivery vehicles, or vectors, to carry the genes that trigger the production of the factor IX (FIX) protein, which is lacking in people with hemophilia B. AAVs deliver the genetic material into living cells to sustain therapeutic effect without causing disease or triggering significant immune responses. In addition, they often target liver cells, which manufacture FIX.

Investigators presented data at the ASH conference on the first eight patients enrolled in the study, all of whom generated increased levels of FIX. Three of the patients needed fewer infusions of FIX concentrates, the other five no longer needed any treatment.

Overall, FIX levels, which were virtually nonexistent in these patients before the study, increased from 1%-6% after receiving the therapy. "Anything over 1 percent will improve the clinical course of the patient" said Arthur Nienhuis, MD, a member of St. Jude's Department of Hematology whose lab helped develop the therapy method. "Clearly, the treatment does work."

The researchers envision eventually testing the therapy on children. They hope to speed up the process by which the vector is created. For the trial, it took about six weeks to create enough vector for the eight study subjects. Studies by other researchers at other institutions are needed to duplicate the results on a larger number of people.


Source:, December 11, 2012