MEDICAL UPDATE MEMO JANUARY 2, 2003

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MEDICAL UPDATE MEMO
JANUARY 2, 2003

                   ANTEGREN CLINICAL TRIAL RESULTS ENCOURAGING
                           AS POTENTIAL MS TREATMENT
SUMMARY
The results of a clinical trial of a monoclonal antibody called natalizumab
(Antegren®) look "very encouraging" as a potential treatment for MS, according to a
study published in the New England Journal of Medicine January 2, 2003. Findings
from this Phase II study were presented initially in September 2001 at a major MS
research meeting in Dublin. In a small double-blind placebo-controlled study of
people with relapsing-remitting or secondary-progressive MS, those receiving the
active treatment had fewer new MS lesions as measured by MRI and fewer relapses
during the six months of treatment, compared with those receiving placebo. Larger
Phase III clinical trials of Antegren alone and in combination with interferon beta-1a
(Avonex) are already underway in Canada, the United States and Europe.

DETAILS
Results of a small Phase II double-blind placebo-controlled study of the monoclonal
antibody natalizumab (Antegren®) have now been published. The results are
promising since study participants on active treatment accumulated fewer new
enhancing MS lesions detected by magnetic resonance imaging (MRI) and also had
fewer MS relapses. These findings were originally reported at the 17th Congress of
the European Committee on Treatment and Research in MS, in Dublin, September
2001.

Antegren is a molecule which is designed to inhibit potentially damaging immune
cells from leaving the bloodstream and crossing through the “blood-brain-barrier” into
the brain and spinal cord. Antegren blocks this movement by attaching to a specific
adhesion molecule on the immune cell surface known as alpha-4 integrin. This
binding may inhibit immune cells from leaving the bloodstream. Antegren was
initially developed by Elan Corporation and is now being co-developed by Elan and
Biogen Inc.

Study details:
   • 214 people with relapsing-remitting or secondary-progressive MS with relapses
      were enrolled at 26 clinical centres in Canada, the United States and Britain.
      Participants received either 3 or 6 mg of Antegren per kilogram of body weight


        Founding member of the International Federation of Multiple Sclerosis Societies/Associated with the Canadian Medical Association.
        Membre fondateur de la Fédération internationale des associations de la sclérose en plaques/Affilliée à l’Association médicale canadienne.
     or inactive placebo intravenously (into the vein) once every four weeks for six
     months.
   • The primary goal was to evaluate safety and to determine the drug’s impact on
     the accumulation of new “enhancing” MRI lesions. Secondary goals were to
     evaluate the impact on MS relapses and progression of disability.

Key findings:
  • According to published results, Antegren significantly reduced the
      accumulation of new lesions detected by gadolinium-enhanced MRI. An
      average of 9.6 new lesions was seen in the placebo group and 0.7 and 1.1 new
      lesions seen in the low- and high-dose Antegren groups, respectively.
  • Relapses were also reduced: 27-placebo treated participants had relapses during
      the six-month treatment period, compared with 13 and 14 participants with
      relapses in the low- and high-dose Antegren groups.
  • Following the treatment period, new MRI detected lesions and MS relapses
      reappeared.
  • No changes in measures of disability were detected in any of the groups.
  • Antegren was relatively well tolerated. Treatment was not associated with any
      specific side effects although there was a trend to more infections with therapy.
  • Quality of life improved for those on the drug compared to placebo during the
      treatment period.

Conclusion
The results of this short-term clinical study look very encouraging, said Dr. Paul
O’Connor, director of the MS Clinic, St. Michael’s Hospital, Toronto, and North
American study coordinator for the Phase II trial. Two large Phase III studies of
Antegren are now underway in Canada, the United States and Europe. One study of
Antegren alone involves 900 participants with relapsing-remitting MS and is designed
to determine whether the drug can slow the rate of disability and reduce the rate of
MS relapses. In the second study, Antegren is being combined with Avonex
(interferon beta-1a), and being tested in 1,200 participants with relapsing-remitting
MS to determine whether the combination is more effective than Avonex alone in
slowing the rate of disability and reducing MS relapses.

ASK MS Code 1.4.1.60.5.f


National Research Department
National Communications & Social Action Department
                                                                   \medmmoantegrenjan03


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