Only Once-a-Week Multiple Sclerosis Therapy Now Even More Convenient

Biogen, Inc. (NASDAQ/BGEN) today announced the U.S. Food and Drug Administration (FDA) has approved a new prefilled syringe for AVONEX® (Interferon beta-1a), designed to make treatment even more convenient for people with multiple sclerosis (MS).

AVONEX, the only once-a-week treatment for MS, is now approved in a convenient, prefilled syringe that makes it even easier to administer. Biogen expects the prefilled syringe to be available in August and replace the currently available form of AVONEX. As with the current form of AVONEX, the new formulation will be 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.

Burt Adelman, M.D., Biogen’s Executive Vice President, Research and Development, said, “Biogen is pleased to provide patients with an AVONEX prefilled syringe. This formulation offers greater convenience for patients and, as with the existing formulation, has a neutralizing antibody rate of 5 percent.”

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.

The most common side effects associated with AVONEX treatment are flu-like symptoms, myalgia, fever, fatigue, headache, chills, nausea, vomiting, pain and asthenia.

AVONEX, which is administered by intramuscular injection, 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 www.AVONEX.com .

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 www.biogen.com .

Safe Harbor
This press release contains forward-looking statements regarding the availability of the prefilled syringe and the prefilled syringe replacing the currently available form of AVONEX. These statements are based on the Company’s current beliefs and expectations, and are subject to risks and uncertainties that could cause actual results to differ materially. There is no assurance, for example, that the availability of the prefilled syringe will not be affected by unexpected technical or manufacturing issues. For more detailed information on risks and uncertainties associated with the Company’s activities see the Outlook section in MD&A; of the Company’s Annual Report on Form 10-K and quarterly reports on Form 10-Q filed with the Securities and Exchange Commission. The Company does not undertake any obligation to publicly update any forward-looking statements.

Media Contact:
Amy Brockelman
Manager, Public Affairs
Biogen, Inc.
(617) 914-6524

Investment Community Contact:
Christina Dillon
Manager, Investor Relations
Biogen, Inc.
(617) 679-2812