Today, the parent companies published an update on their plans for Tysabri. For the multiple sclerosis indication, they plan to submit a Supplemental Biologics License Application in the "coming weeks." A Supplemental BLA is defined by the FDA as:

"An application to allow a company to make changes in a product that already has an approved new drug application (NDA). Center for Drug Evaluation and Research must approve all important NDA changes (in packaging or ingredients, for instance) to ensure the conditions originally set for the product are still met."

In other words, they will attempt to amend the labelling information (in currently unknown ways) to account for the discovered PML risk and to return the product to market.

On a related note, Tysabri was also being used for the treatment of the digestive disorder Crohn's disease, and for Rhuematoid Arthritis. The safety evaluation for those two indications is yet to be completed, and should be done on the same time frame as the submission of the MS supplemental BLA. This means either or both of the following: MS is viewed as the most important application of Tysabri and/or the data in MS is clear enough to understand the PML risk to the point the product could be returned to market in a relatively safe manner.

Overall good news, though the timeline for submission, FDA action, and resumption of marketing (if the FDA agrees with the supplement, of course) is nebulous at this moment.

Please click "read more" for the full press release...

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Press Release
Source: Elan Corporation, plc

Elan and Biogen Idec Provide an Update on TYSABRI(R) Tuesday September 20, 4:05 pm ET

DUBLIN, Ireland & CAMBRIDGE, Mass.--(BUSINESS WIRE)--Sept. 20, 2005--Elan Corporation, plc (NYSE: ELN - News) and Biogen Idec (NASDAQ: BIIB - News) 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
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Source: Elan Corporation, plc