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FDA approves drug for rare enzyme deficiency

/ Source: The Associated Press

The first-ever treatment for an extremely rare and often fatal genetic disease that interferes with the body’s ability to tap built-up stores of sugar for energy received federal approval Friday.

The Food and Drug Administration said it approved Myozyme as the first treatment for Pompe disease, also known as acid maltase enzyme deficiency. The disease affects fewer than 10,000 people worldwide. It’s rapidly fatal in newborns.

“If this disease can be identified at a very early age and can in fact be treated, then this is a lifesaving treatment,” said Dr. Valerie Cwik, medical director for the Muscular Dystrophy Association, which supported research on the enzyme replacement therapy.

An inherited lack of or deficiency in the enzyme alpha-glucosidase causes the neuromuscular disease. The enzyme is responsible for breaking down glycogen, a form of sugar stored in the muscles. As a result, Pompe patients suffer a buildup of glycogen in the muscles, eventually weakening them. Few newborns with the disease live past their first birthday. When the disease strikes later in life, it can be severely debilitating and, eventually, life-shortening.

The FDA granted Myozyme priority review under the Orphan Drug Act, which encourages development of treatments for rare diseases and conditions. Myozyme is made by Genzyme Corp. It is the Cambridge, Mass., company’s fourth enzyme-replacement therapy for a rare disease.

“This approval is another example of the benefits of the Orphan Drug program,” Dr. Steven Galson, director of the FDA’s Center for Drug Evaluation and Research, said in a statement. “Until now, Pompe disease has had no approved treatment.”

The treatment is not a cure for the disease, said Dr. David Meeker, who directs the Genzyme business unit responsible for Myozyme. Clinical trials conducted with infant patients showed they were able to live longer, without the need for breathing help, than would otherwise have been expected, Meeker said. Myozyme’s effect on long-term survival remains unknown.

Myozyme is to be administered intravenously every two weeks. Meeker said it is expected to be priced in the range of other enzyme-replacement therapies, which can cost $200,000 to $300,000 a year. The cost for infant patients, who require less medication, can be substantially less. The therapy should be available within two weeks.

Myozyme will bear the most serious warning label, cautioning patients of the risk of life-threatening allergic reactions.

Brian White, 42, said since he was diagnosed with Pompe disease late in 2003, walking, breathing, showering and lying flat have all gradually become more difficult.

“You know the phrase, ’can’t walk and chew gum?’ I can’t do that,” said White, who does regulatory work for a gas pipeline company. The Fairfax, Va., man added that he would consider undergoing treatment.

“I think I am at the point where I am forced to make that decision. I don’t think I can go on without it,” he said.