WASHINGTON — Patients running out of medicines to fight the AIDS virus now have another option: a new class of drugs that has proved to work when others fail.
The Food and Drug Administration approved the drug Fuzeon on Thursday for adults and for children age 6 and older. As many as 100,000 U.S. patients could benefit, and experts predicted a flurry of new research could produce more drugs like it.
Manufacturers said the drug, which is expected to cost about $20,000 a year, should be available by month's end, although initially only to a limited number of people.
Fuzeon is the first in a new class of medications, called fusion inhibitors, that work by preventing the AIDS virus from invading white blood cells that are the primary targets of HIV.
By contrast, today's AIDS drugs all work after the virus already has invaded those cells, by blocking either of two substances that the virus uses to reproduce and spread.
"This is a great day for people with HIV who are in trouble," said Dr. Jacob P. Lalezari, of Quest Clinical Research in San Francisco, who directed the research. "The approval of a drug with a new mechanism of action is terribly important for those patients who are failing current therapy."
Taking combinations of the older drugs has allowed large numbers of patients to turn their infection from a rapid death sentence into a more manageable chronic disease. But because the virus mutates continually, patients with drug-resistant HIV are finding fewer options.
Fuzeon's is the first approval in seven years for a new type of AIDS drug. Experts predicted it would drive significant new research.
"It will not only help patients, but stimulate research in developing new classes of drugs," said Dr. Debra Birnkrant, director of the division of antiviral drug products at the FDA.
Another leading researcher, Dr. Calvin Cohen of CRI New England, said there has already been "a flurry of interest" from other companies.
The approval led the New England Journal of Medicine to release a study early that supports the FDA's conclusion that Fuzeon can be effective for people who have become resistant to other AIDS drugs.
Scientists and patients have awaited Fuzeon's arrival eagerly, but with some anxiety, hoping for a new option, while fearful it would not be affordable.
The two manufacturers, Swiss pharmaceutical company Roche, and North Carolina's Trimeris Inc., would not say exactly how much they would charge in the United States. Roche spokeswoman Heather Van Ness said it would be close to the $20,400 a year the company is charging in Europe.
AIDS activists are already protesting the price.
"The excessive price of Fuzeon is going to bankrupt all of the public programs that provide drugs, severely tax private health insurance and result in thousands of people not being able to access life-extending treatment," John Riley of ACT-UP New York, said Friday. "We believe this is extreme price gouging."
Members of his group staged a protest Thursday outside Roche's North American headquarters in Nutley, N.J.
Today's typical HIV cocktails — combinations of three drugs — cost about $15,000 a year. To be most effective, patients should combine Fuzeon with whichever drugs they already are taking that are still working, the FDA said.
One reason for the high cost is that Fuzeon is hard to make. Also, it must be taken by injection twice a day, rotating among the abdomen, thigh and upper arm. Other anti-HIV drugs come in pill form.
Fuzeon, known chemically as enfuvirtide, helps block one of the three steps that HIV takes to slip inside immune cells.
In studies of 1,000 patients with drug-resistant HIV, people who added Fuzeon to their regular medicine were twice as likely to have the virus in their blood dip below detectable levels.
Fuzeon recipients also experienced a significantly greater boost in critical immune cells called CD4 cells, meaning their immune system improves and patients are sick less often.
Many patients eventually die after traditional AIDS drugs stop working, but it takes several years, and this study was not conducted over a long enough period to determine whether Fuzeon would save lives.
The FDA approved the drug on an accelerated basis, meaning it does not yet have long-term data on the drug's effectiveness.
The FDA warned doctors to look out for signs of pneumonia. In the clinical trials, pneumonia was not common, but it was more likely to occur in people taking the drug than in those who were not.
An estimated 850,000 to 950,000 people in the United States are infected with HIV, and there are about 40,000 new infections each year.
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