Results Show Only Once-Weekly Multiple Sclerosis Therapy is Well Tolerated and Has Low Incidence of Neutralizing Antibodies

Biogen, Inc. (NASDAQ/BGEN) today announced that data presented at the Consortium of Multiple Sclerosis Centers’ (CMSC) annual meeting demonstrated that AVONEX® (Interferon beta-1a) was generally well tolerated and produced low levels of neutralizing antibodies in patients treated for up to eight years. AVONEX had a 5 percent rate of neutralizing antibodies in this study, consistent with the low incidence seen in other trials. The safety profile was also found to be generally similar to that in other trials and consistent with post-marketing experience, as described in the AVONEX package insert.

The study, presented at annual meeting of the CMSC in San Diego, was led by Robert Herndon, M.D., Department of Neurology, University of Mississippi VA Medical Center in Jackson, MS. 224 patients were treated for approximately six years; of those patients, 86 were treated for up to eight years. Results of the study show that adverse events were generally consistent with other AVONEX trials. Only 2 percent of the patients discontinued treatment due to adverse events.

“It is important for patients to take a therapy that is well tolerated over the long term,” Dr. Herndon said. “In this study, only 5 percent of patients developed neutralizing antibodies to AVONEX. That low rate is important to me when I choose therapies for my patients.”

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 inhibit the biologic activity of the therapeutic protein. The clinical significance of neutralizing antibodies to AVONEX is unknown.

AVONEX is indicated to slow the progression of disability and reduce the frequency of relapses in relapsing forms of MS, including people who have experienced a first clinical episode and who have brain scans consistent with MS. The most common side effects associated with AVONEX treatment are flu-like symptoms, myalgia, fever, fatigue, headache, chills, nausea, vomiting, pain and asthenia.

AVONEX should be used with caution in patients with depression or other mood disorders and in patients with seizure disorders. AVONEX should not be used by pregnant women. Patients with cardiac disease should be closely monitored. Patients should also be monitored for signs of hepatic injury. Routine periodic blood chemistry and hematology tests are recommended during treatment with AVONEX. Rare cases of anaphylaxis have been reported. Please see complete prescribing information available at .

Multiple Sclerosis
MS is a chronic disease of the central nervous system that affects approximately 400,000 people in North America and approximately 1 million people worldwide. It is a disease of young adults, mostly women, with onset typically between 20 and 40 years of age. Symptoms of MS may include vision problems, loss of balance, numbness, difficulty walking and paralysis.

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.

About Biogen
Biogen is the world’s oldest independent biotechnology company and a leader in biologics research, development and manufacturing. A pioneer in leading edge research in immunology, neurobiology and oncology, Biogen brings novel therapies to improve patients’ lives around the world through its global marketing capabilities. For press releases and additional information about the company, please visit

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