MICHELE NORRIS, Host:
After a series of setbacks, the field of gene therapy has taken an important step forward. A report out today describes work by researchers in France. They have successfully treated two young boys with a rare but fatal genetic disease.
As NPR's Joe Palca reports, this news is good for patients with this particular disease and for the entire field of gene therapy.
JOE PALCA: Finding the gene that causes a disease is just the start in finding a treatment for that disease. No one knows that better than Patrick Aubourg.
PALCA: 1993 is the year Aubourg published a key paper describing the single-gene defect that causes X-linked adrenoleukodystrophy or ALD. It's a devastating neurological disease, incapacitating and ultimately fatal. It's the disease affecting the young boy in the movie "Lorenzo's Oil."
In the years after he isolated the gene, Patrick Aubourg figured out how to repair it and began working on a way to put the repaired gene back into patients.
Enter Amber and Rachel Salzman. They are both mothers of children with ALD. They started a foundation called Stop ALD, committed to finding a treatment for the disease. When they heard about Aubourg's interest in gene therapy, Amber Salzman says she and her sister flew to Paris to meet with him, not so much to ask for his help - their children were past the point where they could benefit from gene therapy - but to see how they could help him.
NORRIS: It's not that we in particular were gene therapy experts by any means. It's just, I think we took this relentless - whatever it is, we will make it happen.
PALCA: Salzman says she and her sister put Aubourg in contact with some American researchers who were developing a new technique for getting repaired genes into patients using something called a lentivirus. By 2006, Aubourg was ready to try the new technique with ALD patients. And now, as he writes in the journal "Science," he appears to have a successful treatment for the disease.
D: I use the term treated. I don't use the term cure. Treated. The disease has been arrested, not reversed, really.
PALCA: But arresting the disease may be enough if the treatment is done before the disease progresses too far.
David Williams of Children's Hospital Boston says one of the biggest hurdles facing would-be gene therapies is getting enough of the repaired gene into patients' cells. Williams says Aubourg's approach seems to have cracked that problem.
D: Even though they have about 10 to 20 percent of the cells apparently carry the new gene, that's enough. It appears to arrest the progression of the disease.
PALCA: One of the other big problems facing gene therapy has been safety. Another French team succeeded in treating a different genetic disease, only to discover that the virus they used to deliver their gene therapy gave their patients leukemia.
Williams says the new approach appears to have avoided that problem.
D: Having said that, these patients are still only three years or so out from their therapy. And so it's still possible that something could evolve, although there's no indication in the molecular analysis that it would evolve.
PALCA: Other researchers are impressed with the French team's results.
D: Oh, I think it's going to change a lot.
PALCA: Jude Samulski is director of the Gene Therapy Center at UNC, the University of North Carolina. He expects many people will want to try the approach on ALD patients.
D: Even here at UNC, we see a lot of these kids. And now that we know there's an approach that may work, we'll start proposing it. Because if they can't get a bone marrow transplant, they have nothing.
PALCA: Bone marrow transplants have been shown to work with ALD patients, but the transplants are risky and frequently there's no donor available.
David Williams of Children's Hospital Boston says the French results may mean gene therapy is finally coming of age.
D: When gene therapy started, there was a lot of predictions that this was going to revolutionize medicine. And it's been a long time to get it to actually work in humans.
PALCA: If the treatment for ALD holds up, it might be the start of that revolution.
Joe Palca, NPR News, Washington.