TYSABRI® (natalizumab) Data at ECTRIMS Reaffirm Positive Effects of Treatment for People with Relapsing Forms of MS

Today, (NASDAQ: BIIB) and , plc (NYSE: ELN) announced that results from 11 company-sponsored TYSABRI presentations, including 10 posters and one platform, will be available for viewing at the 28 Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) in Lyon, France, October 10 – 13.

Key data highlights from ECTRIMS include:

“These data further establish the benefits of TYSABRI in reducing relapse rates and slowing disease progression,” said Alfred Sandrock, M.D., Ph.D., senior vice president, Development Sciences and Chief Medical Officer, Biogen Idec. “Data from TOP demonstrate that patients who began TYSABRI earlier had better outcomes than patients in the study who were switched to TYSABRI at two years, further demonstrating the positive effect TYSABRI can make for those living with MS.”

Multiple sclerosis (MS) is an often debilitating disease of the brain and spinal cord that affects nearly 2.1 million people worldwide. While a number of disease modifying therapies are currently available, an unmet need remains for effective treatment options.

“Common symptoms of MS, such as cognitive difficulties, fatigue and visual function can have a tremendous impact on people living with MS.” said Hans Peter Hasler, Chief Operating Officer, Elan Corporation, plc. “The encouraging outcomes from the data presented at ECTRIMS, together with TYSABRI’s proven efficacy, continue to support its strength as a valuable treatment for MS patients around the world.”

TYSABRI is approved in the United States as a monotherapy for relapsing forms of MS, generally for patients who have had an inadequate response to, or are unable to tolerate, an alternative MS therapy. In the European Union, it is approved for highly active relapsing-remitting MS (RRMS) in adult patients who have failed to respond to beta interferon or have rapidly evolving, severe RRMS. TYSABRI is approved in more than 65 countries.

TYSABRI has advanced the treatment of MS patients with its established efficacy. Data from the Phase 3 AFFIRM trial, which was published in the New England Journal of Medicine, showed that after two years, TYSABRI treatment led to a 68 percent relative reduction (p<0.001) in the annualized relapse rate when compared with placebo and reduced the relative risk of disability progression by 42-54 percent (p<0.001).

TYSABRI increases the risk of progressive multifocal leukoencephalopathy (PML), an opportunistic viral infection of the brain, which usually leads to death or severe disability. Infection by the JC virus (JCV) is required for the development of PML and patients who are anti-JCV antibody positive have a higher risk of developing PML. Factors that increase the risk of PML are presence of anti-JCV antibodies, prior immunosuppressant use, and longer TYSABRI treatment duration. Patients who have all three risk factors have the highest risk of developing PML. Other serious adverse events that have occurred in TYSABRI-treated patients include hypersensitivity reactions (e.g., anaphylaxis) and infections, including opportunistic and other atypical infections. Clinically significant liver injury has also been reported in the post-marketing setting. A list of adverse events can be found in the full TYSABRI product labeling for each country where it is approved.

TYSABRI is marketed and distributed by Biogen Idec Inc. and Elan Corporation, plc. For full prescribing information, including boxed warning and important safety information, and more information about TYSABRI, please visit or .

Biogen Idec uses cutting-edge science to discover, develop, manufacture and market therapies for serious diseases with a focus on neurology, immunology and hemophilia. Founded in 1978, Biogen Idec is the world's oldest independent biotechnology company. Patients worldwide benefit from its leading multiple sclerosis therapies and the company generates more than $4 billion in annual revenues. For product labeling, press releases and additional information about the company, please visit .

Elan Corporation, plc is a neuroscience-focused biotechnology company committed to making a difference in the lives of patients and their families by dedicating itself to bringing innovations in science to fill significant unmet medical needs that continue to exist around the world. Elan shares trade on the New York and Irish Stock Exchanges. For additional information about Elan, please visit .