ICOS Corporation (Nasdaq: ICOS) and Biogen, Inc. (Nasdaq: BGEN) announced today their agreement to collaborate worldwide on the development and commercialization of orally active, small molecule LFA-1 antagonists (including ICOS’ IC747, currently in a Phase 1 clinical trial) as oral therapeutics for the treatment of inflammatory conditions.

Under the terms of the agreement, ICOS and Biogen will cross-license LFA-1 antagonist technology and patents, including IC747 and other LFA-1 antagonists. The two companies will share costs for ongoing development activities. ICOS and Biogen will co-promote and equally share profits. ICOS will receive an $8 million up-front payment and other success-based milestones from Biogen. Additionally, ICOS will receive from Biogen a loan to go towards ICOS’ share of development costs, and such loan may be forgiven upon meeting certain development milestones. Other financial terms were not disclosed.

LFA-1 (Leukocyte Function-associated Antigen-1) is a cell adhesion molecule that promotes
T-cell migration and activation that can lead to inflammatory diseases, including multiple sclerosis, psoriasis, rheumatoid arthritis, and organ transplant rejection. ICOS has developed orally active small molecules that have demonstrated in animal models the ability to inhibit
T-cell migration and activation by blocking LFA-1.

James C. Mullen, Biogen’s President and Chief Executive Officer said, “Biogen is excited about developing an orally active immunomodulatory compound to augment our portfolio of biological modulators. This collaboration is part of Biogen’s ongoing effort to partner-in ‘leading’ molecules that have promising medical and commercial potential. Our goal with ICOS is to commercialize an oral formulation that would significantly enhance treatment options for a wide range of autoimmune and inflammatory diseases.”

“We are very happy to have Biogen as our strategic partner,” stated Paul Clark, ICOS’ Chairman and Chief Executive Officer. “Considering Biogen’s extensive experience in the development of therapeutics for the treatment of the target indications, there will be significant synergies in the collaboration to maximize the strategic value of the LFA-1 program.”

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 ( 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 Biogen, please consult Biogen’s Homepage on the World Wide Web at http://www.biogen.com.

ICOS is a product-driven company that has expertise in both protein-based and small molecule therapeutics. ICOS combines capabilities in molecular, cellular and structural biology, high throughput drug screening, medicinal chemistry, and genomics to develop highly innovative products with significant commercial potential. ICOS applies its integrated approach to specific target areas where it has expertise. ICOS believes this strategy increases the chances of successfully developing commercial products. ICOS has advanced clinical trials in sexual dysfunction, severe sepsis, and pulmonary arterial hypertension. For copies of press releases and additional information about ICOS, please consult http://www.icos.com on the Internet.

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Reference is made in particular to statements regarding the prospects, long-range goals and potential value of the small molecule LFA-1 antagonist program. These forward-looking statements involve risks and uncertainties that could cause the Companies’ results and the timing of certain events to differ materially from those discussed in the forward-looking statements.

Drug development involves a high degree of risk. Success in animal work or early stage clinical trials does not ensure that later stage or larger scale clinical trials will be successful. Factors which could cause actual results to differ materially from the Companies’ current expectations include the risk that the product may not show therapeutic effect or an acceptable safety profile in clinical trials or may not meet 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, or that issues may arise with respect to the intellectual property position of the product, as well as the other risks and uncertainties described from time to time in the Companies’ periodic reports filed with the Securities and Exchange Commission.