BIOGEN RECEIVES “COMPLETE RESPONSE” LETTER FROM FDA ON AMEVIVE® (alefacept) APPLICATION

Biogen, Inc. (NASDAQ/BGEN) today announced that it has received a Complete Response Letter from the U.S. Food and Drug Administration (FDA). The letter is the next step forward in FDA’s review of Biogen’s application for approval to market AMEVIVE® (alefacept) in the United States as a treatment for moderate-to-severe chronic plaque psoriasis. FDA is requesting clarification and information related to data Biogen previously submitted. No new clinical trials were requested prior to approval. The Agency proposed post-marketing clinical studies to further define the safety and effectiveness of AMEVIVE. The Company said it will work closely with FDA to address the questions raised and move forward rapidly in the approval process.

Last month, a Dermatologic & Ophthalmic Advisory Committee convened by FDA voted to recommend AMEVIVE for market approval.

Burt Adelman, M.D., Biogen’s Executive Vice President-Research and Development, said, “The FDA Advisory Committee vote last month was a clear indication of the importance the physician and patient communities place on AMEVIVE as a potential new therapy for psoriasis. This FDA letter brings Biogen another step closer to meeting those unmet needs.”

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® (interferon beta-1a) for treatment of relapsing forms of multiple sclerosis (please see full prescribing information at http://www.avonex.com), and from the sales by licensees of a number of products. 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.

Safe Harbor Statement

This press release contains forward-looking statements regarding the potential for approval and marketing of AMEVIVE. 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. Approval of AMEVIVE is subject to the Company’s ability to work with FDA to adequately address the questions and provide the clarification and information requested in the Complete Response Letter. Approval is also subject to the other risks and uncertainties inherent in drug development, including the risk of unexpected new data or information. Even if approved, there is no assurance that AMEVIVE will be free from technical issues affecting commercialization, manufacturing, or intellectual property disputes or that it will achieve its market potential. For more detailed information on the risks and uncertainties associated with AMEVIVE and 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 McKnight
Associate Director, Public Affairs
Biogen, Inc.
Ph: (617) 679-2723

Investor Contact:

Elizabeth Woo
Director, Investor Relations
Biogen, Inc.
Ph: (617) 679-2812