Biogen Idec to acquire full rights and control of TYSABRI® from Elan for upfront cash and contingent payments

Biogen Idec Inc. (NASDAQ: BIIB) today announced the company has agreed to purchase Elan’s interest in TYSABRI (natalizumab) and upon closing will gain full strategic, commercial and decision-making rights to TYSABRI. Upon the closing of the transaction, the previous collaboration agreement between the companies, whereby worldwide TYSABRI profits were split 50/50, will be terminated along with the agreement’s change of control provisions.

Under the terms of the agreement, Biogen Idec will use its existing cash reserves to make a payment of $3.25 billion to Elan upon the closing of the transaction and make future contingent payments to Elan in an amount equal to 12% of global net sales of TYSABRI for the first twelve months, and thereafter, Biogen Idec will continue to make contingent payments of 18% on annual global net sales of TYSABRI up to $2.0 billion and 25% on annual global net sales that exceed $2.0 billion. In 2014 only, the $2.0 billion threshold will be pro-rated for the portion of 2014 remaining after the first 12 months expires.

Biogen Idec anticipates the transaction will be approximately $0.20 to $0.30 accretive to 2013 GAAP earnings per share and $0.50 to $0.60 accretive to non-GAAP earnings per share, and will continue to be accretive thereafter, depending on the sales trajectory of TYSABRI.

“This is a natural next step for Biogen Idec and TYSABRI, and it underscores our deep, long-term commitment to improving the lives of MS patients around the world,” said George A. Scangos, Ph.D., chief executive officer of Biogen Idec. “TYSABRI is a remarkably efficacious drug, and with the increased awareness of our risk stratification capabilities, we believe MS patients’ use of TYSABRI will continue to expand over the long-term. Full ownership will improve our ability to navigate its role as part of our leadership in MS. We appreciate Elan’s tremendous partnership and the productive approach to our discussions that led to a transaction that benefits the shareholders of both companies. We expect a smooth transition to the closing of the transaction.”

The transaction has been approved by the boards of directors of both companies and is subject to the customary review process under the Hart–Scott–Rodino Antitrust Improvements Act in the United States and other customary review processes. The transaction is expected to close by the end of the second quarter, assuming a standard regulatory approval timeframe.

Centerview Partners LLC is acting as exclusive financial advisor to Biogen Idec. Ropes & Gray LLP is acting as legal counsel to Biogen Idec.

About TYSABRI

TYSABRI is approved in more than 65 countries. 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 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 and more information about TYSABRI, please visit www.biogenidec.com.