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Gene Therapy Lets Hemophiliacs to Skip Weekly Shots in Study

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Dec. 10 (Bloomberg) -- A single dose of a gene therapy let four patients with severe hemophilia stop regular injections of clotting factors previously needed to protect them from bleeding to death, a study showed.

The four patients didn’t have spontaneous hemorrhages, even after participating in activities that caused such episodes in the past. Two others were able to extend the time between injections, according to the study published in the New England Journal of Medicine and presented today at the American Society of Hematology conference in San Diego.

The early results suggest the experimental gene therapy has the potential to prevent the bleeding episodes of hemophilia with a single, long-term treatment, researchers said in the study. People with severe hemophilia usually must get injections of a clotting-factor drug two to three times a week.

“I would imagine, if all the forces come together, that we should have a treatment for patients with hemophilia that’s out in the community in the next five years,” Amit Nathwani, of the University College London’s Cancer Institute and an author of the paper, said today at the conference.

Inherited Disorder

Hemophilia, an inherited disorder that prevents blood from clotting properly, affects 20,000 men in the U.S., according to the Centers for Disease Control and Prevention. The condition rarely occurs in women. The study participants had hemophilia B, which is a deficiency of clotting factor IX and less common that hemophilia A, deficiency of clotting factor VIII.

Patients in the study, whose bodies produced less than 1 percent of the normal amount of clotting factor IX, were getting injections of the standard treatment. After receiving the gene therapy, one patient’s level of blood clotting factor remained stable for 16 months without twice-weekly preventative injections of the concentrates.

No serious or long-lasting toxicity from the therapy was observed in the patients, according to the study.

Use of gene therapy has been controversial, and not always successful. In 1999, 18-year-old Jesse Gelsinger died of a massive immune response within hours of being treated for a liver disease at the University of Pennsylvania in Philadelphia. That was followed in 2007 by the death of a woman who received a modified gene in an arthritis trial.

“Hemophilia has long been one of the disorders thought most likely to be correctable with gene therapy, but previous approaches to deliver the gene have been disappointing,” Susan Shurin, acting director of the U.S. National Heart, Lung, and Blood Institute, a sponsor of the research released today, said in a statement. “If future studies support these findings, it would bring a significant improvement in the quality of life for those living with the disease.”

The hemophilia study also was sponsored by St. Jude Children’s Research Hospital in Memphis, Tennessee, and conducted at University College London.

To contact the reporter on this story: Ryan Flinn in San Francisco at

To contact the editor responsible for this story: Reg Gale at

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