Biogen Idec Reports Top-Line Results from Phase 3 Trial Investigating Dexpramipexole in People with Amyotrophic Lateral

  Biogen Idec Reports Top-Line Results from Phase 3 Trial Investigating
  Dexpramipexole in People with Amyotrophic Lateral Sclerosis (ALS)

 -- EMPOWER trial fails to demonstrate efficacy in primary and key secondary
                                 endpoints --

Business Wire

WESTON, Mass. -- January 3, 2013

Today Biogen Idec (NASDAQ: BIIB) reported top-line results of EMPOWER, a Phase
3 trial investigating dexpramipexole in people with amyotrophic lateral
sclerosis (ALS). The trial did not meet its primary endpoint, a joint rank
analysis of function and survival, and no efficacy was seen in the individual
components of function or survival. The trial also failed to show efficacy in
its key secondary endpoints. Additional analyses of multiple subpopulations
failed to demonstrate any efficacy among these groups. Based on these results,
Biogen Idec will discontinue development of dexpramipexole in ALS.

"We share the disappointment of members of the ALS community, who had hoped
that dexpramipexole would offer a meaningful new treatment option,” said
Douglas E. Williams, Ph.D., Executive Vice President of Research and
Development at Biogen Idec. “Nevertheless, the EMPOWER trial represents a
significant contribution to ALS research, and Biogen Idec is committed to
advancing ALS science. We continue to work with researchers around the world
to understand the causes of ALS and find potential treatments for people with
ALS.”

The company intends to present detailed results at a future medical
conference.

EMPOWER Trial

EMPOWER was a randomized, double-blind, placebo-controlled Phase 3 trial which
enrolled 943 people with ALS at 81 sites in 11 countries. Patients were
randomized on a one-to-one basis to receive either dexpramipexole or placebo.
The primary endpoint was a joint rank analysis of function and survival, known
as the Combined Assessment of Function and Survival (CAFS). In addition to
CAFS, the trial individually evaluated functional decline, survival and
respiratory decline, among other measures.

“As a physician who has treated people with ALS, I hoped with all my heart for
a different outcome,” said Douglas Kerr, M.D., Ph.D., Director of
Neurodegeneration Clinical Research at Biogen Idec.“While these results were
not what we expected, we hope these data will provide a foundation for future
ALS research.”

Biogen Idec’s Commitment to ALS Research

Biogen Idec has several programs underway in ALS. The company recently entered
into a research collaboration with Duke University and HudsonAlpha Institute
to sequence the genomes of up to 1,000 people with ALS over the next five
years in an effort to gain a deeper understanding about the fundamental
genetic causes of the disease. Duke and HudsonAlpha will work with several
world-class researchers who have deep expertise and experience with ALS and
the genes associated with the disease.

Biogen Idec recently created a research consortium in collaboration with
several leading academic research centers to identify new approaches to
treating ALS. Each of the centers involved in this consortium brings different
scientific and technical expertise and a shared goal of improving the
understanding of ALS from a basic science perspective.

In addition, Biogen Idec has committed significant funds to the University of
Massachusetts Medical School ALS Champion Fund. The funding will drive
awareness of ALS and support basic and clinical science research into
potential treatments for ALS and other neurodegenerative diseases.

About Biogen Idec

Through cutting-edge science and medicine, Biogen Idec discovers, develops and
delivers to patients worldwide innovative therapies for the treatment of
neurodegenerative diseases, hemophilia and autoimmune disorders. Founded in
1978, Biogen Idec is the world’s oldest independent biotechnology company.
Patients worldwide benefit from its leading multiple sclerosis therapies and
the company generates more than $5 billion in annual revenues. For product
labeling, press releases and additional information about the company, please
visit www.biogenidec.com.

Safe Harbor

This press release contains forward-looking statements, including statements
about potential treatments for ALS. These statements may be identified by
words such as "believe," "expect," "may," "plan," "potential," "will" and
similar expressions, and are based on the company’s current beliefs and
expectations. Drug development involves a high degree of risk, and only a
small number of research and development programs results in the
commercialization of a product. Success in preclinical work or early stage
clinical trials does not ensure that later stage or larger scale clinical
trials will be successful. In addition, clinical trials may indicate that
product candidates have harmful side effects or raise other safety concerns
that may significantly reduce the likelihood of regulatory approval. For more
detailed information on the risks and uncertainties associated with Biogen
Idec's drug development activities, please review the Risk Factors section of
Biogen Idec's most recent annual or quarterly report filed with the Securities
and Exchange Commission. Any forward-looking statements speak only as of the
date of this press release and the company assumes no obligation to update any
forward-looking statements, whether as a result of new information, future
events or otherwise.

Contact:

Biogen Idec Media Contact:
Ligia Del Bianco, +1-781-464-3260
Manager, Public Affairs
or
Biogen Idec Investor Contact:
Kia Khaleghpour, +1-781-464-2442
Director, Investor Relations