First Biotechnology Product for Arthritis Approved
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FDA today licensed a new genetically engineered protein called etanercept that helps reduce the symptoms of moderate to severe, active rheumatoid arthritis (RA) in patients who have not responded well to other treatments. It can also be used in combination with methotrexate if patients do not benefit enough from use of methotrexate alone.
Although many patients with RA respond well to currently available treatments, many are also disabled and suffer severe pain from the disease. It is estimated that RA, an autoimmune disease, affects more than two million Americans. As many as a third to a half of these people are estimated to have moderate to severe RA.
In every issue of WebMD the Magazine, we ask experts to answer readers' questions about a wide range of topics, including some of the oldest -- and most cherished -- medical myths out there. For our October 2011 issue, we asked Dimitrios Pappas, MD, assistant professor of medicine at Columbia University's College of Physicians and Surgeons, about the long-term effects of one popular childhood activity: knuckle cracking.
Q: My 10-year-old son cracks his knuckles. Is it true that it causes arthritis?
Etanercept (trade-name Enbrel) binds to tumor necrosis factor (TNF), a naturally occurring protein in the body, and inhibits its action. TNF, which promotes inflammation in the body, is found at elevated levels in the fluid surrounding the affected joints of RA patients.
"Etanercept provides yet another example of how the promises of biotechnology are being fulfilled," said Acting FDA Commissioner Michael A. Friedman, M.D. "For some patients with disabling rheumatoid arthritis, this product can significantly reduce pain and swollen joints that have restricted their normal daily activities for years."
In clinical trials, approximately 59 percent of patients treated with etanercept, compared to 11 percent of the untreated groups experienced a significant reduction in symptoms such as tender, swollen and painful joints after six months of treatment.
About 37 percent of patients treated with the new product developed injection site reactions, such as itching, pain or swellings, that were generally mild to moderate and lasted only a few days. Less than 1 percent of patients experienced an allergic reaction when etanercept was given, but no severe reactions were seen.
Although it is theoretically possible that etanercept may affect the body's defenses against infections and malignancies, clinical studies to date have not shown an increase in serious infections or malignancies. However, the company is conducting further studies to look at the long-term safety of the product.
Etanercept has also been studied in 54 children aged 4 to 17 years old with moderate to severe juvenile RA with results similar to those of the adult studies. It is recommended that if possible, children be up-to-date with current vaccine immunization guidelines before starting therapy with etanercept because it is not known whether immunization responses will be affected by treatment.
Etanercept will be co-marketed by the Immunex Corporation, Seattle, Wash. and Wyeth-Ayerst Laboratories, Philadelphia, Pennsylvania, under the trade-name Enbrel.