BIOGEN AND EOS BIOTECHNOLOGY ANNOUNCE GENOMIC TARGET AND THERAPUTIC ANTIBODY COLLABORATION

Biogen, Inc. (NASDAQ: BGEN) and Eos Biotechnology, Inc., today announced the establishment of a multi-year research and development collaboration to identify novel targets for antibody and protein therapeutics in the area of breast cancer. The value of the collaboration to Eos could reach $55 million, not including royalties on sales of products identified through the collaboration.

Eos will share with Biogen results from Eos’ large proprietary gene expression databases derived from breast cancer tumors and normal tissues, which have already yielded several cancer-specific targets. The agreement also includes an option for Eos to produce fully human therapeutic antibodies against validated targets identified in the collaboration.

In return for providing Biogen with exclusive world-wide rights to breast cancer-specific molecules for use in the development of new antibody and secreted protein therapeutics, Eos will receive an up-front payment, research funding and milestone and royalty payments on products resulting from the collaboration. In addition, Biogen has made a $5 million equity investment in Eos.

James C. Mullen, Biogen’s President and Chief Executive Officer, said, “This alliance demonstrates Biogen’s commitment to the oncology marketplace. Breast cancer is one of the most frequently diagnosed types of cancer. More than 100,000 patients throughout the world die each year, and there is clearly room in the marketplace for improved therapeutics. Biogen will use our considerable knowledge and skill in biology and drug development to work with Eos on identifying potential targets and commercializing products.

“We are pleased to be working with Eos, which has proven ability to rapidly identify genomics-derived targets and determine their disease utility. One of the key advantages of Eos’ approach is its ability to survey the entire human genome in a high throughput manner.”

“Biogen’s commitment is an important validation of Eos’ integrated biology and genome-wide profiling technology,” stated David Martin, President & Chief Executive Officer of Eos. “We are delighted to enter into this collaboration with Biogen, a premier biotechnology company with strong biopharmaceutical discovery, development and commercialization capabilities. Eos and Biogen share a common belief that genomics-derived therapeutics products will significantly improve cancer patient care and management in the future.”

In addition to historical information, this press release contains forward-looking statements within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995. Reference is made in particular to statements regarding the possible development and commercialization of therapeutic products arising from the collaboration. These statements are based on the companies’ respective current beliefs and expectations as to such future outcomes. Drug development involves a high degree of risk. Factors which could cause actual results to differ materially from the companies’ current expectations include the risk that the parties may not find appropriate drug candidates, the risk that companies may be blocked from development of a candidate molecule by intellectual property of a third party, the risk that a product arising from the collaboration may not show therapeutic effect or an acceptable safety profile in clinical trials or may not meet applicable regulatory standards, or that problems or delays may arise during clinical trials or in the course of the development, testing or manufacturing of the product as well as the other risks and uncertainties associated with drug development and commercialization described in Biogen’s periodic reports filed with the Securities and Exchange Commission.

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 U.S. and European 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 ( Prescribing Information ). Biogen’s research and development activities are focused on novel products for multiple sclerosis, inflammatory, respiratory, kidney and cardiovascular diseases and in developmental biology 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 www.biogen.com.

Eos Biotechnology, a privately funded biotechnology company in South San Francisco, California, develops, applies and integrates a variety of high-throughput genomics, bioinformatics and biological processes for the creation of novel therapeutic and diagnostic products. Eos technologies are being applied to rapidly and cost-effectively build a pipeline of novel, medically important therapeutics and diagnostics in the areas of oncology, angiogenesis and inflammation, with initial product development efforts focused in the area of therapeutic antibodies. Eos has already established collaborations with Affymetrix, Inc. for the development and manufacturing of GeneChip DNA Arrays; with Medarex, Inc. for the development of fully human antibodies directed against genome-derived targets for treating certain cancers; and with Aventis-Pasteur for genome-derived targets against which to develop cancer vaccines. Further information about Eos and its programs is available at www.eosbiotech.com.