Biogen Idec and Elan Celebrate Second Anniversary of TYSABRI(R) for the Treatment...

Biogen Idec and Elan Celebrate Second Anniversary of TYSABRI(R) for the Treatment of Multiple Sclerosis

TYSABRI's Benefits Continue to Drive Product's Growth with More
Than 31,800 Patients Receiving Treatment
CAMBRIDGE, Mass. & DUBLIN, Ireland--(Business Wire)--
Biogen Idec (NASDAQ: BIIB) and Elan Corporation, plc (NYSE: ELN)
today announced the two-year anniversary of TYSABRI(R) (natalizumab)
as a treatment for relapsing forms of multiple sclerosis (MS), marking
the reintroduction of the product in the United States (US) and the
first international approval. The companies estimate that as of the
end of June 2008, more than 31,800 patients worldwide are receiving
TYSABRI treatment.

Specifically, as of the end of June 2008:

-- In the US, more than 17,800 patients are on TYSABRI
commercially and more than 3,100 physicians have prescribed
the therapy;

-- Outside of the US, nearly 13,400 patients are on TYSABRI
commercially;

-- In global clinical trials, more than 600 patients are on
TYSABRI; and,

-- There have been no confirmed cases of progressive multifocal
leukoencephalopathy (PML) since re-launch in the US and the
first international approval in July 2006.

Cumulatively, in the combined clinical trial and post-marketing
settings:

-- More than 43,300 patients have been treated with TYSABRI; and

-- Of those patients, nearly 13,900 have received at least one
year of TYSABRI therapy and approximately 6,600 patients have
been on therapy for 18 months or longer.

"Since beginning TYSABRI therapy more than 18 months ago, I have
experienced an improvement in my life and how I go about living with
my MS every day," said patient Patricia Substelny. "The benefits have
been significant in terms of reducing the number of exacerbations I
have experienced. I can now confidently work in my garden, cook for my
family and friends, and enjoy what life has to offer. I feel very
fortunate to have TYSABRI as an option to help me manage my MS."

In the two years since reintroduction in the US and the first
international approval, the data continue to demonstrate the benefits
of TYSABRI treatment for patients with relapsing forms of MS. Data
showed that TYSABRI treatment significantly increases the proportion
of patients with MS considered to be disease free, according to
post-hoc analyses of Phase III clinical trials presented at this
year's American Academy of Neurology annual meeting. In addition, new
data from a patient-reported outcomes survey was presented at the
Consortium of Multiple Sclerosis Centers annual meeting showing that
after only three months of treatment with TYSABRI, some patients
reported improvements in overall quality of life, disease level,
functional status and MS symptoms.

Along with TYSABRI's well-established clinical efficacy, growing
health economic data from across the globe has been presented and
published endorsing the pharmacoeconomic benefits of TYSABRI in MS
patients. Based on this data, local health agencies in countries
including Australia, Austria, the Netherlands, the United Kingdom,
Sweden, France and Germany have all recommended TYSABRI for
reimbursement by government-run health agencies.

"During the past two years, my patients who are being treated with
TYSABRI appear to experience very positive benefits from the drug,"
said Dr. Thomas F. Scott, Professor of Neurology, Drexel University
College of Medicine and Director, Allegheny MS Treatment Center in
Pittsburgh. "Many of my patients tell me TYSABRI is helping them to
regain control of their lives."

About TOUCH(TM), TYGRIS and CD INFORM

Before initiating treatment, all US patients, prescribers and
infusion sites must be enrolled in the TOUCH Prescribing Program
(TYSABRI Outreach: Unified Commitment to Health). TOUCH is designed to
determine the incidence of and risk factors for serious opportunistic
infections (OIs), including PML, and to monitor patients for signs and
symptoms of PML while promoting informed benefit-risk discussions
prior to initiating TYSABRI treatment. Physicians report on PML, other
serious OIs, deaths and discontinuation of therapy on an ongoing
basis.

TYGRIS (TYSABRI Global ObseRvation Program In Safety) and CD
INFORM (Crohn's Disease - Investigating Natalizumab through Further
Observational Research and Monitoring) are part of the global risk
management plan for TYSABRI. TYGRIS is expected to enroll 5,000 MS
patients worldwide, including approximately 2,000 - 2,500 patients
from TOUCH. CD INFORM is expected to enroll 2,000 Crohn's patients in
the US. Patients in TYGRIS and CD INFORM are evaluated at baseline and
every six months thereafter for five years. Researchers will evaluate
data including medical history; prior TYSABRI use; prior use of
immunomodulatory, antineoplastic, or immunosuppressive agents; and all
serious adverse events, including PML and other serious OIs and
malignancies.

Adverse event reporting in the post-marketing setting is
voluntary. It is possible that not all reactions have been reported,
or that some reactions are not reported to Biogen Idec or Elan in a
timely manner.

About TYSABRI

TYSABRI is a treatment 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<0.001) in the annualized relapse rate compared to placebo
and reduced the relative risk of disability progression by 42-54%
(p<0.001).

TYSABRI was recently approved to induce and maintain 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 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 is approved in more than 35 countries.

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

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.

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.

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 the 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, that the
companies may encounter other unexpected hurdles, or that new
therapies for MS with better efficacy or safety profiles or more
convenient methods of administration are introduced into the market.
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.

MEDIA CONTACTS:
Biogen Idec
Shannon Altimari, 617-914-6524
or
Elan
Jonathan Birt, 212-850-5664 or +44 20 7269 7205
or
Niamh Lyons, +353 1 663 3602
or
INVESTOR CONTACTS:
Biogen Idec
Eric Hoffman, 617-679-2812
or
Elan
Chris Burns, 800-252-3526
or
David Marshall, +353 1 709 4444

Copyright Business Wire 2008