Positive Year One Results from Biogen Idec Phase 3 ADVANCE Trial of PLEGRIDY™ (Peginterferon Beta-1a) Presented at AAN

  Positive Year One Results from Biogen Idec Phase 3 ADVANCE Trial of
  PLEGRIDY™ (Peginterferon Beta-1a) Presented at AAN Meeting

– Primary and Secondary Endpoints Met After One Year, Including Reductions in
                    Relapses and Disability Progression –

– Additional Data Demonstrate Significant Effects in Decreasing Brain Lesions

Business Wire

WESTON, Mass. -- March 20, 2013

Today Biogen Idec (NASDAQ: BIIB) announced the positive, full first-year
results from its two-year pivotal Phase 3 ADVANCE study of PLEGRIDY™ 
(peginterferon beta-1a), the company’s investigational candidate for
relapsing-remitting multiple sclerosis (RRMS) dosed once every two weeks or
every four weeks. These data, presented today at the American Academy of
Neurology’s 65th Annual Meeting, indicate that PLEGRIDY significantly reduced
multiple sclerosis (MS) disease activity, including relapses, disability
progression and brain lesions, compared to placebo at one year.

“These full first-year results provide a more complete picture of PLEGRIDY and
its positive effects on the reduction of relapse, disability progression and
lesion development,” said Peter Calabresi, M.D., director, the Johns Hopkins
Multiple Sclerosis Center. “These data suggest that, if approved, PLEGRIDY may
offer the benefit of a less frequent dosing schedule, which would be a
meaningful advance for people living with MS.”

Study Results for Two-Week Dosing Arm at Year One:

Primary endpoint:

  *PLEGRIDY met the primary endpoint of reducing annualized relapse rate
    (ARR) at one year by 36 percent compared to placebo (p=0.0007).

Secondary endpoints:

  *PLEGRIDY reduced the proportion of patients who relapsed by 39 percent
    compared to placebo (p=0.0003).
  *PLEGRIDY reduced the number of new or newly enlarging T2-hyperintense
    lesions on brain MRI scans by 67 percent compared to placebo (p<0.0001).
  *PLEGRIDY also demonstrated significant positive effects on disability
    progression by reducing the risk of 12-week confirmed disability
    progression, as measured by the Expanded Disability Status Scale (EDSS),
    by 38 percent compared to placebo (p=0.0383).

Additional results:

  *PLEGRIDY significantly reduced the number of gadolinium-enhancing (Gd+)
    lesions by 86 percent compared to placebo (p<0.0001).
  *The incidence of PLEGRIDY neutralizing antibodies was less than 1 percent.

PLEGRIDY dosed once every four weeks was also shown to be effective, and met
the primary and secondary endpoints in the ADVANCE trial. PLEGRIDY dosed once
every two weeks resulted in a numerically greater treatment effect across
these relapse and MRI endpoints discussed above.

“In the first year of the ADVANCE trial, PLEGRIDY demonstrated strong
efficacy. We saw a marked reduction in relapse rate and this was supported by
MRI results. If approved, PLEGRIDY will make an important therapeutic option
in the injectable treatment segment”, said Gilmore O’Neill, Vice President,
Global Neurology Late Stage Clinical Development at Biogen Idec. “In addition
to these encouraging therapeutic results, PLEGRIDY may reduce the treatment
burden for patients by reducing the number of subcutaneous injections.”

PLEGRIDY showed favorable safety and tolerability profiles in ADVANCE. The
overall incidence of serious adverse events (SAEs) and adverse events (AEs)
was similar among the PLEGRIDY and placebo groups. The most common SAE was
infections, which was balanced across all treatment groups (≤1 percent per
group). The most commonly reported AEs with PLEGRIDY treatment were redness at
the injection site and influenza-like illness.

PLEGRIDY is a new molecular entity in which interferon beta-1a is pegylated to
extend its half-life and prolong its exposure in the body, enabling study of a
less frequent dosing schedule. PLEGRIDY is a member of the interferon class of
treatments and, if approved, would be a new addition to this class, which is
often used as a first-line treatment for MS.

After completing two years in the ADVANCE study, patients have the option of
enrolling in an open-label extension study called ATTAIN and will be followed
for up to four years.

For members of the media interested in more information and additional
resources, please visit www.biogenidec.com/us_media_corner.


The two-year Phase 3 ADVANCE clinical trial is a global, multi-center,
randomized, double-blind, parallel-group, placebo-controlled study designed to
evaluate the efficacy and safety of PLEGRIDY in 1,516 randomized patients with

The study investigates two dose regimens of PLEGRIDY, 125 mcg administered
subcutaneously every two weeks or every four weeks compared to placebo. The
analysis for all primary and secondary efficacy endpoints occurs at one year.
After the first year, patients on placebo are re-randomized to one of the
PLEGRIDY arms for the duration of the second year of the study.

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 the dosage and related therapeutic effects, development and
commercialization of PLEGRIDY™ (peginterferon beta-1a). These statements may
be identified by words such as "believe," "expect," "may," "plan,"
"potential," "will" and similar expressions, and are based on our current
beliefs and expectations. Drug development and commercialization involve a
high degree of risk. Factors which could cause actual results to differ
materially from our current expectations include the risk that unexpected
concerns may arise from additional data or analysis, regulatory authorities
may require additional information or further studies, or may fail to approve
or may delay approval of our drug candidates, or we may encounter other
unexpected hurdles. For more detailed information on the risks and
uncertainties associated with our drug development and commercialization
activities, please review the Risk Factors section of our 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
we assume no obligation to update any forward-looking statements.


Biogen Idec
Lindsey Smith, +1-781-464-3260
Biogen Idec
Kia Khaleghpour, +1-781-464-2442
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