FDA Approves TYSABRI(R) for the Treatment of Moderate-to-Severe Crohn´s Disease

Elan Corporation, plc (NYSE: ELN) and Biogen Idec (NASDAQ: BIIB)
today announced the approval of a supplemental Biologics License
Application (sBLA) by the U.S. Food and Drug Administration (FDA) for
TYSABRI(R) (natalizumab). TYSABRI is now approved for inducing and
maintaining clinical response and remission in adult patients with
moderately to severely active Crohn´s disease (CD) with evidence of
inflammation who have had an inadequate response to, or are unable to
tolerate, conventional CD therapies and inhibitors of TNF-alpha.
TYSABRI will be available for the treatment of CD upon the completion
of key implementation activities related to the approved risk
management plan. The companies anticipate TYSABRI will be available to
Crohn´s patients by the end of February 2008.

"The FDA´s approval of TYSABRI is an important step forward in the
treatment of Crohn´s disease," said Dr. Stephen Hanauer, Professor of
Medicine & Clinical Pharmacology & Chief of the Section of
Gastroenterology at the University of Chicago Pritzker School of
Medicine. "A significant number of patients either fail or cannot
tolerate current therapies. The unique mechanism of action of TYSABRI
affords us a new class of therapy in our fight against this
debilitating disease."

The FDA granted approval based on its review of TYSABRI CD
clinical trial data and overall safety data. The approval is
accompanied by robust labeling with safety warnings; and a CD-specific
risk management plan (including the mandatory TOUCH(TM) Prescribing
Program) designed to inform prescribers, patients and infusion centers
about the use of TYSABRI and to minimize potential risk of progressive
multifocal leukoencephalopathy (PML) and other opportunistic
infections.

"We are delighted that TYSABRI will be available for Crohn´s
patients and their physicians, who continue to need new therapeutic
options with novel mechanisms of action," said Gordon Francis, MD,
Senior Vice President, Global Clinical Development, Elan. "We are
committed to providing therapeutic choice to those patients who can
benefit from TYSABRI, and will continue to work with the FDA and the
medical community to implement the TOUCH(TM) Prescribing Program for
Crohn´s patients."

"We are pleased with the FDA´s decision to make TYSABRI available
to Crohn´s patients suffering from this chronic, debilitating
disease," said Evan Beckman, MD, Senior Vice President, Immunology
Research and Development, Biogen Idec. "Despite the therapeutic
advances of the TNF-alpha inhibitors in CD, there remains a
significant unmet need for Crohn´s patients who have inadequate
responses to, or are unable to tolerate, current CD therapies."

TOUCH(TM) Prescribing Program

The TOUCH(TM) (TYSABRI Outreach: Unified Commitment to Health)
Prescribing Program was developed in conjunction with the FDA to
facilitate appropriate use of TYSABRI and to assess, on an ongoing
basis, the incidence and risk factors for PML and other serious
opportunistic infections associated with TYSABRI treatment. This
program represents Elan and Biogen Idec´s commitment to making the
unique benefits of TYSABRI available in a responsible manner. The
program already has been implemented for patients receiving TYSABRI
therapy for MS.

About Crohn´s Disease

An estimated 500,000 people in the United States have Crohn´s
disease, a chronic and progressive inflammatory disease of the
gastrointestinal tract, which commonly affects both men and women.

The disease usually causes diarrhea and crampy abdominal pain,
often associated with fever, and at times rectal bleeding. Loss of
appetite and weight loss also may occur. Complications include
narrowing of the intestine, obstruction, abscesses, and fistulas
(abnormal channels connecting the intestine and other organs,
including the skin), and malnutrition. Most patients eventually
require surgery, which has both risks and potential short- and
long-term complications.

Crohn´s disease can have a devastating impact on the lifestyle of
patients, many of whom are young and active. Currently there is no
medical or surgical cure for Crohn´s disease. Many patients fail to
respond to current therapies, including biological therapies such as
agents that inhibit tumor necrosis factor alpha (TNF-alpha). Due to
this failure of current therapies in CD, therapies that have alternate
biological targets provide patients and physicians with therapeutic
options.

About TYSABRI

Data from the ENCORE trial showed that TYSABRI induced response
and remission among patients with moderately to severely active
Crohn´s disease, and objective evidence of inflammation, as measured
by elevated C-reactive protein. After 12 weeks of therapy, 60% of
TYSABRI-treated patients attained response, compared to 44% of placebo
treated patients, and 48% of patients had sustained response at both
weeks 8 and 12, compared to 32% of placebo treated patients (p less
than 0.005 for both). Among the patients who had inadequate response
to prior treatment with inhibitors of TNF-alpha, 38% achieved
sustained response at weeks 8 and 12.

Data from the ENACT-2 showed that an additional year of TYSABRI
therapy sustained response and remission among patients with an
initial response to TYSABRI after 3 months in ENACT-1. Of patients
with response in ENACT-1, sustained response during ENACT-2 was seen
in 61% of patients treated with TYSABRI at every visit through an
additional 6 months of therapy, compared to 29% for placebo. This
treatment difference was also sustained through 12 months of
additional therapy (54% vs. 20%). Remission was sustained at every
visit with an additional 6 months or 12 months of TYSABRI in 45% and
40% of patients, respectively, compared to 26% and 15% of placebo
treated patients (p less than 0.005 for all comparisons). Among the
patients that had previously failed TNF-inhibitors, response and
remission was sustained at every visit through an additional 6 months
of TYSABRI in 52% and 30% of patients, respectively. Among patients on
steroids and in whom a clinical response was achieved, approximately
two-thirds were able to discontinue steroids within 10 weeks of
beginning to taper steroids.

TYSABRI increases the risk of progressive multifocal
leukoencephalopathy (PML), an opportunistic viral infection of the
brain that usually leads to death or severe disability. Other serious
adverse events that have occurred in TYSABRI-treated patients included
hypersensitivity reactions (e.g., anaphylaxis) and infections. Serious
opportunistic and other atypical infections have been observed in
TYSABRI-treated patients, some of whom were receiving concurrent
immunosuppressants. Herpes infections were slightly more common in
patients treated with TYSABRI. In MS and CD clinical trials, the
incidence and rate of other serious adverse events, including serious
infections, were similar in patients receiving TYSABRI and those
receiving placebo. Common adverse events reported in TYSABRI-treated
MS patients include headache, fatigue, infusion reactions, urinary
tract infections, joint and limb pain, and rash. Other common adverse
events reported in TYSABRI-treated CD patients include respiratory
tract infections and nausea. Clinically significant liver injury has
been reported in patients treated with TYSABRI in the post-marketing
setting.

TYSABRI has previously been approved for relapsing forms of MS in
the United States and relapsing-remitting MS in the European Union.
According to data that have been published in the New England Journal
of Medicine, after two years, TYSABRI treatment led to a 68% relative
reduction (p less than 0.001) in the annualized relapse rate compared
to placebo and reduced the relative risk of disability progression by
42-54% (p less than 0.001). In addition to the United States and
European Union, TYSABRI is also approved for MS in Switzerland,
Canada, Australia, New Zealand and Israel. TYSABRI was discovered by
Elan and is co-developed with Biogen Idec.

For more information about TYSABRI please visit www.tysabri.com,
www.biogenidec.com or www.elan.com, or call 1-800-456-2255.

About Elan

Elan Corporation, plc is a neuroscience-based biotechnology
company committed to making a difference in the lives of patients and
their families by dedicating itself 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
www.elan.com.

About Biogen Idec

Biogen Idec creates new standards of care in therapeutic areas
with high unmet medical needs. Founded in 1978, Biogen Idec is a
global leader in the discovery, development, manufacturing, and
commercialization of innovative therapies. Patients in more than 90
countries benefit from Biogen Idec´s significant products that address
diseases such as lymphoma, multiple sclerosis, and rheumatoid
arthritis. For product labeling, press releases and additional
information about the company, please visit www.biogenidec.com.

Safe Harbor/Forward-Looking Statements

This press release contains forward-looking statements regarding
TYSABRI. These statements are based on the companies´ current beliefs
and expectations. The commercial potential of TYSABRI 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 we may be unable to adequately address concerns
or questions raised by FDA or other regulatory authorities, that
concerns may arise from additional data, that the incidence and/or
risk of PML or other opportunistic infections in patients treated with
TYSABRI may be higher than observed in clinical trials, or that the
companies may encounter other unexpected 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 and current 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.