Biogen Idec

Biogen Idec
Elan Corporation

Elan Corporation

March 30, 2005 17:35 ET

Elan and Biogen Idec Announce TYSABRI Update






MARCH 30, 2005 - 17:35 ET

Elan and Biogen Idec Announce TYSABRI Update

DUBLIN, Ireland and CAMBRIDGE, Mass.--(CCNMatthews - Mar 30, 2005) -

Elan Corporation, plc (NYSE: ELN) and Biogen Idec (NASDAQ: BIIB)
announced today that their ongoing safety evaluation of TYSABRI®
(natalizumab) has led to a previously diagnosed case of malignant
astrocytoma being reassessed as progressive multifocal
leukoencephalopathy (PML), in a patient in an open label Crohn's disease
clinical trial.

In light of the two previously reported cases of PML in multiple
sclerosis clinical trials, Elan and Biogen Idec initiated an additional
comprehensive safety evaluation of TYSABRI clinical trial patients. In
the course of this safety review, the companies identified a case
warranting reassessment in an open label Crohn's disease clinical trial.
In July 2003, the case was reported by a clinical trial investigator as
malignant astrocytoma. This diagnosis was confirmed at the time by
histopathology. The patient died in December 2003.

As part of this ongoing safety review, the companies, in agreement with
the clinical trial investigator, reassessed the case. Following this
additional evaluation, the diagnosis is being reassessed as PML. The
patient had received 8 doses of TYSABRI over an 18 month period and
prior medication history included multiple courses of immunosuppressant

Elan and Biogen Idec's comprehensive safety evaluation concerning
TYSABRI and any possible link to PML is ongoing. The companies are
reviewing clinical trial data, working with investigators to evaluate
the approximately 3,000 patients in multiple sclerosis, Crohn's disease,
and rheumatoid arthritis trials, and working with PML and neurology
experts. The results of this safety evaluation will be discussed with
regulatory agencies to determine possible re-initiation of dosing in
clinical trials and future commercial availability.

On February 28, 2005, the companies announced that they had suspended
marketing of TYSABRI in multiple sclerosis and dosing in all clinical
trials based on two previously reported cases of PML, a rare and
frequently 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

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

Safe Harbor/Forward Looking Statements

This press release contains forward-looking statements regarding the
potential for TYSABRI. These statements are based on the companies'
current beliefs and expectations, and are subject to risks and
uncertainties that could cause actual results to differ materially.
There is no assurance, for example, that the serious adverse events
discussed above were not caused by TYSABRI, that there are not or will
not be more such serious adverse events or that we will be able to gain
sufficient information to fully understand the risks associated with the
product. There is also no assurance that the companies will be able to
resume marketing and sales of TYSABRI. For more detailed information on
the risks and uncertainties associated with TYSABRI and the companies'
drug development and other activities, see the periodic and other
reports of Biogen Idec Inc. and Elan Corporation, 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.


Contact Information

    Media Contacts:
    Biogen Idec
    Jose Juves, 617-914-6524
    Anita Kawatra, 212-407-5740 or 800-252-3526
    Brian McGlynn, 212-407-5740 or 800-252-3526
    Investor Contacts:
    Biogen Idec
    Elizabeth Woo, 617-679-2812
    Emer Reynolds, 353 1 709 4000800 252 3526