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Not all Interferon-beta Treatments are Created Equal in Developing Neutralizing Antibodies

Neutralizing Antibodies can significantly decrease the effectiveness of IFN-b in the treatment of MS

TORONTO, ONTARIO -- July 14, 2005 -- Three studies published in Neurology which included more than 1200 patients, confirm that the three interferon preparations used to treat relapsing-remitting multiple sclerosis (MS) vary in their rate of production of neutralizing antibodies (NAbs).

Further, there is agreement that NAbs reduce or eliminate the biologic activity and clinical efficacy of the interferon-beta (IFN-b) therapies.

Once-weekly Avonex® (interferon beta-1a IM) was shown to be significantly less likely to induce the development of NAbs than the other two available interferon therapies (Rebif® and Betaseron®). Since NAbs reduce or eliminate the clinical benefits of the interferons, these studies highlight a concern for MS patients, neurologists and those who pay for these medications.

For the many Canadians living with MS, and currently being treated with IFN-b therapy, this is important data.

"MS is a chronic disease, and patients need to have the confidence that their therapy will retain its efficacy throughout the course of treatment, which is often for many years," commented Dr. Stanley Hashimoto, neurologist and former medical director of the University of British Columbia MS Clinic, Vancouver, Clinical Director of the UBC MS Clinic, Vancouver, British Columbia. "These studies confirm that in MS, high titre and persistent NAbs are very important in eliminating the efficacy of the therapeutic agent. It is important that we have available a less immunogenic option such as Avonex®."

While each of the studies showed slightly different rates of NAbs, Avonex® (interferon beta-1a IM) consistently demonstrated the lowest rates as compared to the other IFNb therapies. For example, in the first study the Danish Multiple Sclerosis Study group (Neurology 2005;65:33-39) concluded, "Unlike previous findings reported in the literature we did not find any difference in the proportion of patients treated with [Betaseron®] and [Rebif®] who became NAb-positive, but could confirm that Avonex® is much less immunogenic."

In the second study, Kappos and associates (Neurology 2005;65:40-47) analyzed 395 patients over four years in a controlled trial, and clearly demonstrated the loss of efficacy in terms of relapse rate reduction and disability progression over a significant number of years. It can be assumed from this research, that persisting NAbs beyond the four years will continue to suppress the therapeutic activity of the interferons. This was also echoed by Drs. Giovannoni and Goodman in their Editorial (Neurology 2005;65:6-8).

The third study, authored by Dr. Gordon Francis et al. (Neurology 2005;65:48-55), concluded that, "Neutralizing antibody development in IFN-b-treated patients is correlated with reduced efficacy and is a potential cause for renewed (MS) disease activity."

"Many patients being treated for MS are not getting the efficacy they deserve because of the neutralizing effect of NAbs," said Dr. Hashimoto "This is not to mention the fact that our healthcare system is paying for these drugs without realizing the potential negative effects of neutralizing antibodies."

The Danish Multiple Sclerosis study group agreed that the presence of NAbs decrease or eliminate efficacy of the interferons. They recommended that to avoid these negative consequences, all patients on the therapies should be tested at six-month intervals for two years when it becomes less likely the new positivity will develop. Routine testing will assure patients that they are self-injecting their medication and getting benefit from it.

With recent concerns about existing and future MS treatments, patients and physicians are reassessing currently available therapies, like the interferons. As a result, it is more important than ever to re-evaluate which therapy will provide efficacy over the long-term, including minimizing the formation of NAbs.

Multiple sclerosis is the most common neurological condition affecting young adults in Canada. MS most often strikes young adults -- women and men between 20 and 40 who are in their most productive family and career years. Women are affected twice as often as men.


Avonex® is a registered trademark of Biogen Idec Inc.
Rebif® is a registered trademark of Serono Canada Inc.
Betaseron® is a registered trademark of Berlex Canada Inc.


SOURCE: Biogen Idec Inc.

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