Biogen Idec's MS franchise to present at the 25th Congress of ECTRIMS

Biogen Idec (NASDAQ: BIIB) today announced more than 70 platform and poster presentations from the company’s multiple sclerosis (MS) franchise being presented during the 25^th Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) in Düsseldorf, Germany. Held from September 9 -12, 2009, ECTRIMS is the world’s largest medical meeting dedicated to MS. Data being presented will include the company’s currently marketed products, TYSABRI^® (natalizumab) and AVONEX^® (Interferon beta-1a), as well as three Phase III programs; BG-12 (dimethyl fumarate), PEGylated interferon beta-1a and Fampridine-SR.

“Biogen Idec is a recognized leader in the field of MS research and treatment. AVONEX pioneered the interferon class of treatments and TYSABRI has offered patients a new level of efficacy not seen with any other approved MS therapy. The success seen to date by the tens of thousands of patients who have taken these therapies, along with the hope of our late-stage pipeline, is a testament to how we are setting new expectations in the treatment of MS as we work towards the ultimate goal of finding a cure for this disease,” said Alfred Sandrock, MD, PhD, senior vice president, Neurology Research and Development, Biogen Idec.

The following represents select data highlights from the company’s portfolio of marketed products and late-stage pipeline programs. All data are embargoed until the date and time of the presentation.

TYSABRI

There are 47 TYSABRI posters and presentations during the Congress, including the following posters which show the potential of TYSABRI to redefine successful MS treatment by offering improvement across functional, imaging and patient-reported measures:

• Natalizumab improves disability on the Multiple Sclerosis Functional Composite in a randomised, double-blind, placebo-controlled study of patients with relapsing multiple sclerosis (poster P434);
• Evolution of voxel-wise magnetization transfer ratio in natalizumab and interferon beta-1a IM treated patients with multiple sclerosis. A case-control study (poster P721); and
• What do multiple sclerosis patients experience? Effect of natalizumab on disease-specific quality of life over time (poster P872).

AVONEX

There are 13 AVONEX posters and presentations during the Congress, including:

• CHAMPIONS: 10-year follow-up after a clinically isolated syndrome in patients at high risk for developing multiple sclerosis (poster P446), which supports the benefits of starting early treatment with AVONEX;
• Reducing the risk of informative censoring in long-term study designs: evidence from ASSURANCE (poster P535), which supports the benefits of long-term treatment with AVONEX; and
• An evaluation of adverse skin reactions in patients with multiple sclerosis (poster P787), which focuses on fewer injection site reactions seen in patients taking AVONEX.

Biogen Idec’s Phase III Pipeline

Thirteen posters focusing on Biogen Idec’s extensive MS pipeline will be presented during ECTRIMS. Biogen Idec’s phase III MS portfolio consists of BG-12, a novel oral compound that recently completed accrual in the CONFIRM Phase III clinical trial; PEGylated interferon beta-1a, which may reduce the frequency of treatment injections and provide patients with an effective and more convenient dosing option; and Fampridine-SR, an oral sustained-release compound being developed to improve walking ability in people with MS. Highlights on these compounds include:

• Dimethyl fumarate (BG00012) inhibits astrocyte and microglial activation (poster P457), which provides evidence that the compound may have a dual mechanism of action thought to demonstrate anti-inflammatory and neuroprotective properties;
• Pharmacokinetic, pharmacodynamic, and safety profiles of PEGylated interferon beta-1a in healthy volunteers: results from two phase 1 clinical studies (poster P436), which are the data that supported the advancement of the compound into the ongoing Phase III ADVANCE trial; and
• Interim analysis of an open-label extension study of sustained release fampridine in patients with multiple sclerosis (presentation 43) , which are data from a long-term extension study of the first phase III Fampridine-SR trial sponsored by Acorda Therapeutics, known as MS-F203.

Biogen Idec will also host two symposia during ECTRIMS. Both will feature presentations from world-renowned experts in MS, with a focus on how Biogen Idec’s portfolio is allowing MS patients to expect more from their MS treatments:

• Thursday, September 10, 2009 - 7:15 p.m. to 8:15 p.m. CET - “Redefining Success in MS: Advancing a New Treatment Paradigm"
• Friday, September 11, 2009 - 12:45 p.m. to 1:45 p.m. CET - “Redefining Success in MS: Challenging Treatment Expectations"