Data Presented at the 60th Annual Meeting of the American Academy of Neurology Offers...

Data Presented at the 60th Annual Meeting of the American Academy of Neurology Offers Additional Support for Plasma Exchange as a Potential Tool to Accelerate TYSABRI(R) Removal

CHICAGO--(Business Wire)--
Biogen Idec (NASDAQ: BIIB) and Elan Corporation, plc (NYSE: ELN)
today announced additional findings from the PLEX study which shows
that plasma exchange accelerates the removal of TYSABRI(R)
(natalizumab) from blood serum in patients and may help improve
central nervous system immune response based on an in vitro model. The
data was presented today at the 60th Annual Meeting of the American
Academy of Neurology (AAN). Plasma exchange is one of several research
efforts the companies have underway to learn more about potential
interventions or treatments for progressive multifocal
leukoencephalopathy (PML).

"The goal of these studies is to evaluate the value of plasma
exchange in patients who may develop PML. The data are encouraging as
they show that removal of TYSABRI through plasma exchange may be a
potential intervention to rapidly clear TYSABRI and restore immune
function when clinically appropriate," said the study's lead author,
Bhupendra O. Khatri, MD, Medical Director of the Regional MS Center,
Aurora St. Luke's Medical Center, Milwaukee, WI.

PLEX is an open-label, single-arm, multicenter exploratory study
involving 12 patients with relapsing-remitting multiple sclerosis
(MS), designed to explore whether plasma exchange could significantly
reduce the concentration of TYSABRI in blood serum and alpha
4-integrin receptor saturation. Plasma exchange is an established
method of removing large molecules from the body's blood circulation.
Based on the PLEX findings, plasma exchange was effective at
accelerating the normal decline of TYSABRI serum concentrations.

A sub-study of PLEX, also presented today at the meeting,
evaluated the effect of plasma exchange on the migration of certain
immune cells, called leukocytes, across an in vitro model of the
blood-brain barrier. TYSABRI was shown to reduce the migration of
these cells across the blood-brain barrier. The results showed that
plasma exchange improved the ability of these cells to migrate across
the blood brain barrier, potentially reestablishing normal central
nervous system immune response.

Plasma exchange was generally well tolerated with no increase in
MS disease activity. There were no study discontinuations due to
adverse events and all patients returned to TYSABRI treatment without
complications. While further studies are being conducted, plasma
exchange has been shown to hold potential as an intervention in the
setting of PML.

Abstracts from the larger PLEX study, "Plasma Exchange Accelerates
the Decline of Serum Natalizumab Concentration in Patients with
Multiple Sclerosis: Results of the Natalizumab PLEX Study"
(Presentation #S22.005) and the sub-analysis, "Plasma Exchange
Augments Leukocyte Transmigration Across an In Vitro Blood-Brain
Barrier In Natalizumab-Treated Patients with Multiple Sclerosis"
(Presentation #S27.005) are available on-line at the AAN's website.

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 30 countries including the United
States and many countries throughout the European Union, as well as
Switzerland, Canada, Australia, New Zealand and Israel.

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 and the PLEX study. 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.

MEDIA CONTACTS:
Biogen Idec
Shannon Altimari, 617-914-6524
or
Elan
Jonathan Birt, 212-850-5664
or
Elizabeth Headon, +353 1 498 0300
or
INVESTOR CONTACTS:
Biogen Idec
Eric Hoffman, 617-679-2812
or
Elan
Chris Burns, + 353 1 709 4444 or 800-252-3526

Copyright Business Wire 2008