Vernalis and Biogen Idec to collaborate on research for Parkinson’s disease

• Joint collaboration to boost Parkinson’s disease research

• Vernalis to receive immediate $10 million licence fee

• Biogen Idec to make initial investment of $6 million in new Vernalis shares

Reading, UK and Cambridge, Mass., USA, June 24^th 2004 – Vernalis plc (LSE: VER, Nasdaq: VNLS) and Biogen Idec (Nasdaq: BIIB) today announce that they have entered into an agreement to advance research into Vernalis’ adenosine A_2A receptor antagonist program, which targets Parkinson’s disease and other central nervous system disorders.

Under the agreement, Biogen Idec receives exclusive worldwide rights to develop and commercialize Vernalis' lead compound, V2006, which recently completed an initial Phase I clinical study in healthy volunteers.  In addition, Biogen Idec has the right to develop one back-up compound to V2006 and receives option rights over Vernalis' A_2A antagonist research program.  Initially, the collaboration will focus on completing the Phase I program for V2006, with the goal to begin Phase II proof of concept studies of V2006 in Parkinson’s disease patients in 2005.

Biogen Idec will pay Vernalis an initial license fee of $10 million, a series of further payments if program milestones are met, and royalties on commercial sales of collaboration products. Biogen Idec will make an immediate investment of $6 million through subscription for 6,218,487 new Vernalis ordinary shares, representing 4.19 percent of Vernalis’ enlarged issued share capital, at a price of 53 pence per share and has committed to purchase an additional $4 million in the event of a future Vernalis financing. Excluding royalties, total potential payments to Vernalis could exceed $100 million. Biogen Idec will fund future development under the collaboration, and Vernalis will retain an option to co-promote collaboration products in the United States.

“This is an important program for Vernalis, and we are delighted to have attracted a partner of Biogen Idec’s calibre to help us take it forward,” said Simon Sturge, chief executive officer, Vernalis. “Parkinson’s disease can be a very difficult and debilitating condition. Today’s announcement is a valuable endorsement of our A_2A program, and fulfills our promise to announce a strong product collaboration in the second quarter.”

James Mullen, president and chief executive officer of Biogen Idec, added, “We look forward to applying the expertise we have developed with our neurology franchise to V2006, a promising product that will bolster our growing small molecule portfolio.  In addition, this partnership brings us one step closer to our corporate goal to in-license 50 percent of our pipeline by 2010.”

Parkinson’s disease is a progressive movement disorder that affects approximately one percent of the population over the age of 65, or about 1.5 million people in the United States. Common symptoms of the disease include stiffening of the muscles, difficulty in moving, tremors and shaking. Parkinson’s is caused by nerve degeneration and cell death in the brain, leading to the loss of dopamine, a neurotransmitter that is involved in the control of voluntary movement.

Most conventional treatments for Parkinson’s disease are based on the replacement or enhancement of dopamine in the brain. These treatments are generally effective in the short term, but efficacy tends to diminish over time and the emergence of side effects increases the level of disability. Vernalis’ adenosine A_2A receptor antagonist program is designed to restore the imbalance of neurotransmitters caused by the loss of dopamine.

Enquiries:

Vernalis plc

Simon Sturge, Chief Executive Officer

Tony Weir, Chief Financial Officer

+44 (0)118 977 3133

Brunswick Group (for analyst, financial media enquiries)

Jon Coles; Wendel Carson

+44 (0)20 7404 5959

Biogen Idec

Amy Ryan (media contact)

+1 617-914-6524

Elizabeth Woo (investor community contact)

+1 617-679-2812

Safe Harbor/Forward Looking Statements

This news release contains forward-looking statements regarding the clinical and therapeutic expectations of Vernalis’ compounds. These statements are based on the companies’ current beliefs and expectations. They are subject to the risks inherent in drug development, including the risks that the effects of the compounds in larger clinical trials may not be as expected or that there may be safety issues or other problems or delays in clinical trials, unexpected technical or manufacturing hurdles, or intellectual property disputes.  Drug development involves a high degree of risk.  Only a small number of research and development programs result in the commercialization of a product.  Success in animal models or early stage clinical trials does not ensure that later stage or larger scale clinical trials will be successful. . For more detailed information on the risks and uncertainties associated with the companies’ drug development and other activities, see the periodic reports of Biogen Idec Inc. and Vernalis plc filed with the Securities and Exchange Commission. The companies assume no obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise.

NOTES TO EDITORS

Adenosine A_2A receptor antagonists

The use of selective adenosine A_2A receptor antagonists helps to restore the imbalance of neurotransmitters that is caused by the loss of dopamine in Parkinson’s disease. This may provide a novel approach to treat the symptoms of Parkinson’s disease and it is hoped that this mechanism of action may also slow or stop the progression of the disease. In particular, A_2A receptor antagonists may be able to restore function in Parkinson’s disease patients without inducing side effects such as nausea and dyskinesias (uncontrolled movements). Laboratory studies also suggest that the adenosine A_2A receptor may be a novel target for the discovery of a new class of antidepressant drugs.

V2006

V2006 (formerly VR 2006) was selected as a development candidate from the Vernalis A_2A antagonist research program in April 2002. Vernalis has recently completed an initial Phase I single ascending dose study of V2006 in healthy male volunteers. The results showed that the drug was well tolerated and that exposure increased with dose. Potentially therapeutic blood levels (based on predictions from pre-clinical studies) were achieved following the lowest dose tested. The drug also had a mean plasma half-life that would be consistent with a simple, once-daily dosing regimen.

About Biogen Idec

Biogen Idec creates new standards of care in oncology 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 product labeling, press releases and additional information about the company, please visit www.biogenidec.com.

About Vernalis

Established in September 2003 following the merger of British Biotech and Vernalis Group, Vernalis plc is pursuing a growth strategy based upon successful pipeline development and further consolidation within the biotechnology sector. Operating from state-of-the-art R&D facilities in Reading (UK) and in Cambridge (UK), the company is equipped to undertake the full development of compounds from discovery through to product registration. In May 2004 Vernalis reacquired the North American rights to frovatriptan, its first approved product, and the Company is in the process of selecting a new partner to market this product in the US and realise the significant potential of frovatriptan in the treatment of menstrually-associated migraine. For more information, please visit www.vernalis.com.

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