BIOGEN SAYS REGULATORY AGENCIES IN U.S. AND EUROPE HAVE OFFICIALLY ACCEPTED FILINGS FOR AMEVIVE® (Alefacept) FOR TREATMENT OF PSORIASIS

Biogen, Inc. (NASDAQ/BGEN) said today that the U.S. Food and Drug Administration (FDA) and the European Agency for the Evaluation of Medicinal Products (EMEA) have completed their initial reviews of Biogen’s license application relating to the use of AMEVIVE® (alefacept) in moderate-to-severe psoriasis. The applications are now considered filed and accepted for review effective in Europe as of September 17 and in the U.S. as of October 4, 2001.

This does not mean that the FDA has fully reviewed the data or that a license has been issued.

Biogen, Inc., winner of the U.S. National Medal of Technology, is a biopharmaceutical 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 international sales of AVONEX® (Interferon beta-1a) for treatment of relapsing forms of
multiple sclerosis, and from the worldwide sales by licensees of a number of products, including alpha interferon and hepatitis B vaccines and diagnostic products. (Please see www.avonex.com for full prescribing information.) 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