People with hemophilia lack a substance that helps blood clot. (Shannon Muskopf: Flickr)

In a preliminary study, six patients in England were successfully treated by gene therapy for the blood-clotting disease hemophilia B. Researchers injected each patient with the correct form of the gene that makes the needed substance that helps blood to clot, called a clotting factor.

“I think it’s a significant advancement in gene therapy and a treatment for hemophilia,” said Mark Kay, Professor at Stanford’s School of Medicine and a co-author of the study. “It’s been over a year for some of the patients and they are continuing to make the [clotting] factor. We have to start at low doses and work our way up. We have patients that are at 10 percent level for half a year.”

That 10 percent is remarkable. In hemophilia, people with a severe form of the disease have less than one percent of the clotting factor. Those with 10 percent are often able to live a normal life.

“I’m very excited about it,” said Dieter Gruenert, Ph.D., Adjunct Professor at UCSF. “People have been working on this for quite some time. Hopefully this will provide an impetus for further support and funding in this country for these kinds of studies.”

The field of gene therapy has long been marked by setbacks. “There was disappointment because people over-promised what was going to happen in a certain time frame,” Kay explained. “Like anything it takes longer for things to come to fruition and there were side effects that actually made it very difficult.”

Indeed, at least one of the patients had an immune reaction in this study. But because of past experiences, researchers were watching patients closely and treated them promptly.

Matching the optimism of the doctors were hemophilia patients themselves. Brian Smith, 45, of Oakland, was diagnosed with hemophilia B when he was just six weeks old. When he was a boy, the treatment was whole blood transfusions. Today the treatment is protein therapy. Smith says he carries three boxes of medicine with him everywhere he goes and must give himself intravenous infusions every other day. He’s been waiting for a gene therapy advance.

“It’s always been bad news,” he said in an interview today. “But this is a breakthrough we’ve all been waiting for, for a very long time. It’ll make my life so much easier.”

Smith currently receives a “giant box” of medicine at a cost of about $30,000 a month. He added that he’s grateful for the good health insurance he has.

The research was made available online over the weekend in the New England Journal of Medicine. An accompanying editorial by Dr. Katherine Ponder at the Washington University School of Medicine in St. Louis called it a “landmark,” adding that, if successful, gene therapy could yield tremendous cost savings. The current medication has a lifetime cost per adult patient of up to $20 million. In developing countries, many patients die at a young age.

The research continues. “The next step is to treat additional patients and see how much variation there is from patient to patient and make sure this immune response issue is something that can be treated,” Kay said. “There’s been a lot of work over the years and things are finally paying off, but move forward with cautious optimism. This looks really promising but we still need to do more studies in humans before we can make long-term predictions about the success of the therapy.”