Biogen Idec And mondoBIOTECH Sign Collaboration And Licensing Agreement To Develop And Commercialize Aviptadil For Pulmonary Arterial Hypertension

Cambridge, MA and Basel, Switzerland (September 14, 2006) - Biogen Idec (NASDAQ: BIIB) and mondoBIOTECH AG, a private Swiss biotechnology company, today announced the signing of an exclusive collaboration and license agreement for Biogen Idec to develop, manufacture and commercialize Aviptadil, a clinical compound for the treatment of Pulmonary Arterial Hypertension (PAH).

Under terms of the agreement, mondoBIOTECH will receive a $7.5 million upfront payment and up to $30 million in milestones payments for successful development and commercialization of Aviptadil in PAH in the United States (US) and Europe, as well as royalty payments on commercial sales. Separately, Biogen Idec intends to make a minority equity investment of $5 million in mondoBIOTECH during an envisaged initial public offering.

“This in-licensing opportunity supports our strategic initiative to expand into new therapeutic areas where we can leverage our global capabilities in serving specialized medical markets with high unmet need,” said James C. Mullen, Biogen Idec’s President and Chief Executive Officer (CEO). “Aviptadil has the potential to be an important therapy in treating pulmonary arterial hypertension, an often deadly disease with few effective treatment options for patients. We look forward to developing Aviptadil for these patients and building on the strong work initiated by mondoBIOTECH.”

“Biogen Idec is a premier biotechnology partner with a global structure, excellent clinical development and commercialization capabilities, and a strong record of accomplishments. We are excited to enter this collaboration which is a validation for our business model addressing fatal and rare lung diseases,” said Fabio Cavalli, CEO of mondoBIOTECH.

“Biogen Idec’s support will strongly advance the development of Aviptadil in PAH and our scientific efforts in identifying novel therapies for rare diseases,” stated Dorian Bevec, Ph.D., Chief Science Officer of mondoBIOTECH.

In accordance with the agreement, Biogen Idec will be responsible for the global manufacturing, clinical development, regulatory approval and commercialization of Aviptadil. Biogen Idec intends to finalize the development plan for Aviptadil and initiate additional clinical work in 2007.
About Aviptadil

Aviptadil is a synthetically produced human peptide (Vasoactive Intestinal Peptide) with Orphan Drug Designation status for PAH in the European Community and in the US. In addition, Aviptadil is the first drug to receive combined, parallel scientific advice for clinical development in PAH from the US Food and Drug Administration and the European Medicines Agency.

An open-label Phase II study, designed to evaluate the efficacy and safety of inhaled Aviptadil in patients with PAH, achieved its primary efficacy endpoint, showing an improvement in physical exercise as measured by an increase in walking distance with three or six months of treatment. No significant adverse events were observed in the eight PAH patients treated in this trial. Larger studies will be necessary to fully define the safety profile of Aviptadil.
About Pulmonary Arterial Hypertension (PAH)

PAH is a debilitating and life-threatening disorder characterized by increased pressure in the pulmonary arteries. Patients suffer from shortness of breath, fatigue, chest pain, and ultimately heart failure and premature death. PAH can occur with no clear cause (idiopathic PAH) or can be inherited (familial PAH), and is frequently secondary to other conditions such as scleroderma, congenital heart disease, HIV/AIDS or other disorders. PAH patients are typically classified by functional ability on the World Health Organization (WHO) criteria, increasing in severity from Class I to Class IV.

The disease affects approximately 100,000 to 200,000 people worldwide. Despite increasing awareness of the disease among clinicians, PAH is frequently undiagnosed and the unmet medical need of patients continues to be high.

About mondoBIOTECH

mondoBIOTECH AG, a private Swiss breathing swiss air™ biotech company headquartered in Basel is focused on development of treatment options for fatal and rare lung diseases. In addition to PAH, the company has a variety of clinical Phase II studies in pulmonary diseases ongoing. For more information, please visit www.mondoBIOTECH.com.

About Biogen Idec

Biogen Idec creates new standards of care in oncology, neurology and immunology. As a global leader in the development, manufacturing, and commercialization of novel therapies, Biogen Idec transforms scientific discoveries into advances in human healthcare. For press releases and additional information about the company, please visit www.biogenidec.com.

Biogen Idec Safe Harbor

This press release contains forward-looking statements regarding the agreement with mondoBIOTECH and the development of Aviptadil. Drug development involves a high degree of risk. Only a small number of research and development programs result in commercialization of a product. Factors which could cause actual results to differ materially from Biogen Idec’s current expectations include the risk that the company may not be able to demonstrate the safety and efficacy of Aviptadil at each stage of the clinical trial process; technical hurdles relating to the manufacture of Aviptadil may be encountered; the company may not be able to meet applicable regulatory standards or regulatory authorities may fail to approve Aviptadil; and the company may encounter other unexpected hurdles. For more detailed information on the risks and uncertainties associated with Biogen Idec’s drug development activities, see the section entitled “Risk Factors” in Biogen Idec’s quarterly report on Form 10-Q for the fiscal quarter ended June 30, 2006 that was filed with the Securities and Exchange Commission, as well as other periodic and current reports of Biogen Idec filed with the Securities and Exchange Commission. Biogen Idec assumes no obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise.

Contact Information

Jose Juves

Director, Public Affairs

Biogen Idec

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