Replacing a missing enzyme in people with Fabry's disease reverses the damage caused by the rare, inherited disorder, according to a study on the first-ever treatment for the disease.
Those with Fabry's disease are lacking an enzyme that breaks down a fatty substance in the body. Without the enzyme, the substance accumulates in blood vessels, leading to kidney failure, heart attack or stroke. Symptoms include pain in the feet and hands, a skin rash and the inability to sweat. The average life span for those with Fabry's (fa-BRAY) disease is about 40 years.
An estimated one in 40,000 men has the disease.
Researchers gave Fabry patients intravenous infusions of the enzyme, called alpha-galactosidase A, which had been genetically engineered. The treatment cleared deposits from the kidneys, heart and skin, the researchers reported in Thursday's New England Journal of Medicine.
``For the many, many years that I've seen these patients _ and some I've followed for 30 years _ I've only been able to give them hope,'' said Dr. Robert J. Desnick of Mount Sinai School of Medicine in New York, who led the research. ``I think we now have something to offer them, perhaps more than hope. And this is to me a major accomplishment.''
Desnick said scientists thought the treatment would work but couldn't get enough of the enymze before genetic engineering. The biotech company Genzyme Corp., which paid for the study, is seeking government approval to market the enzyme as Fabrazyme in the United States and Europe. Desnick is a consultant to Genzyme and has received grants from the company.
A second company, Transkaryotic Therapies Inc., also has applied for approval of its own enzyme replacement therapy, called Replagal.
Last year, Genzyme sued Transkaryotic Therapies, accusing it of patent infringements on the enzyme. Transkaryotic Therapies has denied the allegations and the lawsuit is still pending.
In the study reported Thursday, researchers enrolled 58 Fabry patients in medical centers in the United States and Europe in 1999. Half were given 11 infusions of the enzyme over 20 weeks. The other half was given a dummy solution.
Researchers focused on the treatment's effectiveness on the kidneys, since kidney failure is a frequent and serious complication of the disease. Deposits of the fatty substance _ globotriaosylceramide _ were cleared in 20 of the 29 patients or 69 percent, compared to none in the comparison group. Deposits also were reduced significantly in the skin and heart, the researchers reported.
After the initial study, all 58 patients were given the enzyme. The results after six months confirmed the earlier outcomes, Desnick said. He said the patients are continuing to receive the enzyme every other week, and would have to continue treatment for the rest of their lives.
``These are very, very important changes that are going to impact quality of life,'' Desnick said. ``These people are going to be able to live much more normal lives and they are going to live longer.''
Dr. William A. Gahl of the National Institutes of Health said research is needed to determine whether the treatment prevents some of the other complications such as the pain, skin rash and eye problems. He said the treatment is very promising, especially since there is precedent in effective enzme-replacement therapy for Gaucher's disease, another enzyme-deficiency disorder
``I'm almost certain that (enzyme replacement) will be the therapy of choice within a few years,'' said Gahl, who wrote an editorial accompanying the study.