New Arthritis Drug Draws FDA Warning
A popular arthritis drug licensed only last fall may be linked to serious infections that have killed six people, the Food and Drug Administration announced Wednesday.
About 25,000 people have taken the drug Enbrel, prescribed to treat rheumatoid arthritis, since it went on the market in November, and 30 individuals have been reported becoming ill.
Six of them died within two to 16 weeks of starting the drug, the FDA said, stressing that a number of these patients had histories of chronic or recurrent infections, preexisting infections, diabetes or other conditions that made them vulnerable to infection.
The agency is not removing the drug from the market. It is only warning doctors who prescribe Enbrel to be aware of the potential problems and to monitor their patients closely--especially those who develop a new infection while taking the drug.
The agency also has asked the companies that developed and jointly market the drug--Immunex Corp. of Seattle, and Wyeth-Ayerst Laboratories of Philadelphia--to conduct further studies to determine the risk of infection associated with the drug.
Previous studies did not show an increase in serious infections in arthritis patients taking Enbrel.
But unexpected reactions, which are not always apparent when a drug is studied in a small number of people--typically a few thousand--often appear once a drug has hit the market and goes into widespread public use.
And the FDA has become very sensitive in recent months to hazards posed by newly licensed drugs and is trying to develop strategies to catch problems before they get out of hand.
“Our company wants to find the answers to the question: Is there a risk of serious infection with our drug? We are committed to providing the FDA with additional studies,” said Tim Warner, a spokesman for Immunex. “We want the answer. Patients want the answer. And physicians want the answer.”
Rheumatoid arthritis afflicts more than 2 million Americans. The disease develops when a patient’s immune system goes awry and attacks the joints, causing inflammation and stiffness, often resulting in severe disability.
Dr. Arthur Weaver, director of clinical research at the Arthritis Center of Nebraska, who has studied Enbrel for several years, defended the drug.
“The patients I . . . treat with Enbrel often have long-standing, severely active disease,” he said. “It is not uncommon for these patients to have complex medical histories, including underlying risk factors that could lead to infection.
“It is not surprising or unexpected that patients of this nature may develop infections,” Weaver added. “[I] . . . remain comfortable prescribing Enbrel for appropriate patients under appropriate circumstances.”
The FDA stressed, however, that while patients may be predisposed to infections, “significant concerns remain that Enbrel may contribute.”
Many of the reported infections occurred shortly after initiation of Enbrel therapy, the agency said. Enbrel works by inhibiting the action of tumor necrosis factor, a substance produced as part of the body’s natural defenses against serious infection.
In studies of Enbrel as a treatment for sepsis, a bacterial infection, patients who took the drug died at a rate higher than expected. That raises further questions about the drug’s relationship to serious infections, the FDA said.
