First Biotechnology Product for Arthritis Approved
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.
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This new product is not approved to treat
other types of arthritis, such as osteoarthritis, a disease associated with the
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
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.