HIGHER DOSES OF INTERFERON BETA-1A GIVE NO ADDED BENEFIT.

Biogen, Inc. (NASDAQ/BGEN), Cambridge, Mass., has announced that one of the most debated questions in MS therapy, whether higher doses of Interferon beta-1a are more effective, has been conclusively answered with the release of new data. Results from the largest clinical trial ever completed in Relapsing Multiple Sclerosis (RMS) have shown that AVONEX (Interferon beta-1a) administered at doses of 30 mcg and 60 mcg IM once weekly are equally effective in reducing disability progression -- the primary end point of the study.

"For the first time, we have a study which provides clear information about the dose effect of interferons. This is the only study in MS specifically designed to investigate whether higher doses of interferon are clinically more effective than lower doses. The results mean that doctors can be confident that AVONEX 30 mcg IM once weekly is the right dose to use. Increasing the dose cannot be justified since it is clear that such a strategy achieves no additional clinical benefit," said Professor Michel Clanet, University of Toulouse, the Principal Investigator of the study.

Burt Adelman, M.D., Biogen's vice president of Medical Research, said, "This study is further proof of the efficacy of AVONEX 30 mcg IM once weekly. The results show that patients treated with 30 mcg of AVONEX did just as well as those treated with 60 mcg. Furthermore, the efficacy seen was the same as that in the original Phase III study by Jacobs et al. Patients and physicians now have conclusive evidence that AVONEX, 30 mcg once weekly, is the right dose to slow the progression of physical disability that is associated with this disease."

The randomized, double-blind trial of 802 patients was conducted at 38 centers in 10 countries in Europe. The study was the largest-ever completed in relapsing MS. Patients were followed for at least three years. Entry criteria required that patients have relapsing MS, as defined by two exacerbations in the preceding three years, and an EDSS score between 2.0 and 5.5, inclusive. EDSS score is a measurement of disease severity.

AVONEX is the world's leading treatment for relapsing forms of multiple sclerosis. In the United States, there are more patients on AVONEX than on all other MS therapies combined.

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. 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 additional information, visit http://www.biogen.com or call [phone].