The most recent patient achieved FIX levels of between 8 and 12 percent of normal during the eight weeks after gene transfer and did not have protein prophylaxis even though he was training for a marathon, the researchers reported. He also had transient elevation of liver enzymes, although they did not reach the upper limit of normal.
Hemophilia has been known through history, but the first case of hemophilia owing to FIX deficiency was reported in 1952 and was dubbed Christmas disease after the patient, 10 year-old Stephen Christmas.
The study is "important for both a subtle and obvious reason," according to Dr. Thomas DeLoughery of the Oregon Health & Science University in Portland, Ore. The subtle reason is that the study shows that factor levels of only a few percent of normal can prevent spontaneous bleeding, he wrote in an email to ABC News and MedPage Today.
"This therapy will greatly improve the lives of patients with hemophilia by reducing the numbers of bleeds and need for therapy," he said, although there will still be a need for the protein in cases of trauma or surgery. More obvious is that hemophilia therapy is very expensive, and this may reduce costs. "Some patients will need up to a million dollars' worth of factor to prevent bleeding, so this reduction in factor use should translate into cost savings," DeLoughery said. "This is a game changer."