Elan Corporation

DUBLIN, Ireland & CAMBRIDGE, Mass.--(BUSINESS WIRE)--Sept. 20, 2005--Elan Corporation, plc (NYSE: ELN) and Biogen Idec (NASDAQ: BIIB) announced today that in the coming weeks they expect the safety evaluation of TYSABRI® (natalizumab) in Crohn's disease and rheumatoid arthritis will be completed, and that they will submit a supplemental Biologics License Application for TYSABRI in multiple sclerosis (MS) to the U.S. Food and Drug Administration.

On August 9, 2005, the companies announced the completion of the safety evaluation of TYSABRI in MS, which resulted in no new confirmed cases of progressive multifocal leukoencephalopathy (PML). The companies have previously reported three confirmed cases of PML, two of which were fatal.

On February 28, 2005, Biogen Idec and Elan announced that they voluntarily suspended TYSABRI from the U.S. market and all ongoing clinical trials based on reports of PML, a rare and potentially fatal, demyelinating disease of the central nervous system.

About Elan

Elan Corporation, plc is a neuroscience-based biotechnology company. We are committed to making a difference in the lives of patients and their families by dedicating ourselves 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, London and Dublin Stock Exchanges. For additional information about the company, please visit http://www.elan.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 product labeling, press releases and additional information about the company, please visit http://www.biogenidec.com.

Safe Harbor/Forward-Looking Statements

This press release contains forward-looking statements regarding the regulatory path forward and safety evaluation of TYSABRI. The regulatory path forward is subject to a number of risks and uncertainties. Factors which could cause actual results to differ materially from the companies current expectations include the risk that concerns may arise from additional data or analysis, including the ongoing safety evaluation, or that the companies may encounter other unexpected delays or hurdles. There is also no assurance that the companies will be able to gain sufficient information to fully understand the risks associated with TYSABRI or that the companies will be able to resume marketing and sales of TYSABRI. The completion of the safety evaluation is subject to a number of risks and uncertainties, including the difficulty of analyzing complex data and results and unanticipated logistical hurdles. Drug development and commercialization involves a high degree of risk. For more detailed information on the risks and uncertainties associated with the companies' drug development and other activities, see the periodic reports that Biogen Idec and Elan have 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.

CONTACT: Elan 
Media:
Davia B. Temin, 212-407-5740
OR
Elizabeth Headon, 353-1-498-0300
OR
Investor:
Emer Reynolds, 353-1-709-4000
OR
Chris Burns, 800-252-3526
OR
Biogen Idec
Amy Brockelman, 617-914-6524
OR
Oscar Velastegui, 617-679-2812

SOURCE: Elan Corporation, plc