Biogen, Inc. (NASDAQ/BGEN) announced today that the U.S. Food and Drug Administration (FDA) has approved a label change for AVONEX, lowering the rate of occurrence of neutralizing antibodies to 5 percent from the original label rate of 24 percent.

Recent studies with multiple sclerosis patients given AVONEX for at least 1 year showed the presence of neutralizing antibodies at the rate of 5 percent (13 of 261 patients). The clinical significance of neutralizing antibodies to AVONEX is unknown.

“Biogen is pleased the FDA has reviewed these new clinical data and determined that the neutralizing antibody rate with AVONEX is notably lower than the rate reported from our first Phase III clinical trial,” said Burt Adelman, M.D., Biogen´s Executive Vice President, Research and Development.

“The manufacturing of biologics is extremely complex,” Dr. Adelman continued. “Since AVONEX was approved in 1996, we´ve taken important steps to improve our manufacturing processes. We believe these modifications result in a lower percentage of AVONEX-treated patients developing neutralizing antibodies.”

All therapeutic proteins have the potential to cause an immune response in the human body, such as the production of specific antibodies. A subset of these antibodies, called neutralizing antibodies, can attach to proteins and inhibit their biologic activity.


AVONEX is the leading treatment for relapsing forms of multiple sclerosis worldwide, with more than 120,000 patients on therapy. It was launched in the U.S. in 1996 and later in Europe for the treatment of relapsing forms of MS to slow the progression of disability and reduce relapses. AVONEX is marketed internationally in more than 65 countries.

The most common side effects associated with AVONEX treatment are flu-like symptoms, muscle ache, fever, and chills. Other common side effects seen, but not statistically different between AVONEX and control groups, were headache, pain and asthenia (weakness). These side effects usually go away within a day after the injection and occur less often as the treatment continues.

AVONEX should be used with caution in people with depression and people with seizure disorders. AVONEX should not be used by pregnant women. People with cardiac disease should be closely monitored. Routine periodic blood chemistry and hematology tests are recommended during treatment with AVONEX. Please see complete prescribing information available at www.AVONEX.com.

About Biogen

Biogen, Inc., winner of the U.S. National Medal of Technology, is a biotechnology company principally engaged in discovering and developing drugs for human healthcare through genetic engineering. Headquartered in Cambridge, MA, the Company´s revenues are generated from worldwide sales of AVONEX for treatment of relapsing forms of multiple sclerosis, and from the sales by licensees of a number of products. (Please see full prescribing information at http://www.avonex.com.) Biogen´s research and development activities are focused on novel products to treat inflammatory and autoimmune diseases, neurological diseases, cancer, fibrosis and congestive heart failure. The Company maintains active clinical research programs in protein therapeutics, small molecules, genomics and gene therapy. For copies of press releases and additional information about the Company, please consult Biogen´s homepage on the World Wide Web at http://www.biogen.com.

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