Agency Approves Drug to Treat Genetic Disorder That Can Lead to Retardation
The Food and Drug Administration on Thursday approved the first drug to treat a rare genetic disorder that can lead to mental retardation, possibly allowing some people to relax a regimented diet now used to control the disease.
All babies born in the United States are screened for the disease, called phenylketonuria, or PKU. To avoid damage to the brain, people with the disease must adhere to a strict low-protein diet, particularly in childhood but also later in life.
The new drug, called Kuvan, “will be life-changing for some patients,” said Dr. Stephen D. Cederbaum, a professor at the University of California, Los Angeles, who is an adviser to BioMarin Pharmaceutical, the company that developed the drug.
Dr. Cederbaum said that one of his patients, a 25-year-old man who began taking Kuvan as part of a clinical trial, was able to get his first taste of cheese and pizza and to eat enough other foods that “for the first time in his life, he’s not hungry.”
But Dr. Cederbaum said there was also some resistance to the drug because of its price, especially since some patients would get little or no benefit.
BioMarin said that Kuvan would cost an average of $57,000 a year. It would be less than that for small children but could be more than $200,000 for large adults getting the highest dose. The company, based in Novato, Calif., said it expected insurers to pay for the drug.
There are at least 12,000 people in the United States with PKU, according to BioMarin, which collaborated with the German pharmaceutical company Merck on developing the drug.
People with the disease have a deficiency of an enzyme that breaks down phenylalanine, an amino acid in food. Without the enzyme, the levels of the amino acid build up, causing damage.
Kuvan, known generically as sapropterin dihydrochloride, is a form of BH4, a chemical found in the body that assists the enzyme in breaking down the amino acid. In one clinical trial, Kuvan reduced levels of phenylalanine in the blood by an average of about 30 percent. But for some people with no enzyme, just adding more of the helper chemical would not make a difference.
Dr. Daniel Shames, director of the division of gastroenterology products at the F.D.A., said Kuvan would be effective in 20 percent to 50 percent of patients. Patients would have to try the drug for a month or two since there is no way to predict in advance whether it will work, he said.
There has been some concern that people taking the drug might relax their diets too much, so that the net effect of the drug would be to make things worse.
Dr. Shames warned patients to maintain their diets. “The effects of this drug can be overridden by increasing your dietary intake of phenylalanine,” he said.
Virginia Schuett, editor of National PKU News, said in the fall edition of the newsletter that the safety of taking Kuvan for years was still unknown.
“In cases where the diet is not well controlled, the benefits may easily outweigh the potential risks,” Ms. Schuett wrote. “However, I am less certain at this point whether the potential risks are worth the expected benefits for children and others who are well controlled on the diet.”
BioMarin said that it expected sales of Kuvan to reach $35 million to $70 million next year. The company’s stock rose $1.58 to $29.76 in regular trading Thursday and then climbed to over $33 in after-hours trading, after the company announced the price of the drug.
By Andrew Pollak
Source : http://www.nytimes.com/2007/12/14/health/14genetic.html?_r=1&ref=us&oref=slogin
All babies born in the United States are screened for the disease, called phenylketonuria, or PKU. To avoid damage to the brain, people with the disease must adhere to a strict low-protein diet, particularly in childhood but also later in life.
The new drug, called Kuvan, “will be life-changing for some patients,” said Dr. Stephen D. Cederbaum, a professor at the University of California, Los Angeles, who is an adviser to BioMarin Pharmaceutical, the company that developed the drug.
Dr. Cederbaum said that one of his patients, a 25-year-old man who began taking Kuvan as part of a clinical trial, was able to get his first taste of cheese and pizza and to eat enough other foods that “for the first time in his life, he’s not hungry.”
But Dr. Cederbaum said there was also some resistance to the drug because of its price, especially since some patients would get little or no benefit.
BioMarin said that Kuvan would cost an average of $57,000 a year. It would be less than that for small children but could be more than $200,000 for large adults getting the highest dose. The company, based in Novato, Calif., said it expected insurers to pay for the drug.
There are at least 12,000 people in the United States with PKU, according to BioMarin, which collaborated with the German pharmaceutical company Merck on developing the drug.
People with the disease have a deficiency of an enzyme that breaks down phenylalanine, an amino acid in food. Without the enzyme, the levels of the amino acid build up, causing damage.
Kuvan, known generically as sapropterin dihydrochloride, is a form of BH4, a chemical found in the body that assists the enzyme in breaking down the amino acid. In one clinical trial, Kuvan reduced levels of phenylalanine in the blood by an average of about 30 percent. But for some people with no enzyme, just adding more of the helper chemical would not make a difference.
Dr. Daniel Shames, director of the division of gastroenterology products at the F.D.A., said Kuvan would be effective in 20 percent to 50 percent of patients. Patients would have to try the drug for a month or two since there is no way to predict in advance whether it will work, he said.
There has been some concern that people taking the drug might relax their diets too much, so that the net effect of the drug would be to make things worse.
Dr. Shames warned patients to maintain their diets. “The effects of this drug can be overridden by increasing your dietary intake of phenylalanine,” he said.
Virginia Schuett, editor of National PKU News, said in the fall edition of the newsletter that the safety of taking Kuvan for years was still unknown.
“In cases where the diet is not well controlled, the benefits may easily outweigh the potential risks,” Ms. Schuett wrote. “However, I am less certain at this point whether the potential risks are worth the expected benefits for children and others who are well controlled on the diet.”
BioMarin said that it expected sales of Kuvan to reach $35 million to $70 million next year. The company’s stock rose $1.58 to $29.76 in regular trading Thursday and then climbed to over $33 in after-hours trading, after the company announced the price of the drug.
By Andrew Pollak
Source : http://www.nytimes.com/2007/12/14/health/14genetic.html?_r=1&ref=us&oref=slogin
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