Gene therapy study offers proof of potential breakthrough on hemophilia

A transatlantic team of investigators has presented some promising--though very early stage--breakthrough data on a new gene therapy for hemophilia B. The investigators say that their gene therapy program came close to curing four of 6 patients, spurring the body to produce enough clotting factor to eliminate the need for regular protein injections. And the other two were helped by the treatment, with a reduced need for injections.

One in every 30,000 people carries a genetic defect that prevents them from producing a protein, Factor IX, which the body needs to create a natural blood clotter. Building on 25 years of gene therapy work, the team from University College London and St. Jude Children's Research Hospital adapted a benign virus to essentially infect liver cells with the right genetic material. And a 20-minute infusion pushed levels of Factor IX to a range of two percent to 12% of normal. The high end of that range is enough to eliminate most of the lethal threats posed by hemophilia.

"They would be able to go about their normal daily lives without any problems," Dr. Amit Nathwani from University College London told the BBC. "The only time that they would have a problem is if they were involved in a road traffic accident or had a big fall from a building site. In the absence of severe major trauma these individuals would not know that they have haemophilia."

That's good, but the researchers are targeting a 20% hike in Factor IX levels and they'll be tweaking their gene therapy approach to try and get there. They'll also be looking to avoid a spike in liver enzymes seen in two patients, a classic warning signal in drug development.

"The idea of treating hemophilia with gene therapy has been around for 25 years, but the problem was how to do it right," Ronald G. Crystal, chairman of the department of genetic medicine at Weill Cornell Medical College, tells The Wall Street Journal. "This is an important breakthrough because it is the first success in one of the plasma deficiency disorders and shows gene therapy is feasible."

- read the story from the BBC
- get The Wall Street Journal's article