The interferon beta drugs widely used in relapsing-remitting multiple sclerosis (MS) may not delay progression

TUESDAY, July 17, 2012 (MedPage Today) — The interferon beta drugs widely used in relapsing-remitting multiple sclerosis (MS) may not delay progression of the disease in real-world practice, researchers found.

In a prospective registry, the drugs didn’t predict a lower risk of becoming disabled compared with untreated contemporary controls, instead yielding a hazard ratio of 1.30 after adjustment for disease duration and other baseline factors.

The numbers looked a little better for interferon beta users when compared with untreated historical controls from the pre-interferon era, but they still didn’t reach significance, Helen Tremlett, PhD, of the University of British Columbia in Vancouver, and colleagues reported in the July 18 issue of the Journal of the American Medical Association.

“The study is useful in terms of giving patients realistic expectations on what they can hope to gain in terms of benefits from the drug treatments,” Tremlett said in a video interview with the journal.

However, clinicians and patients shouldn’t abandon interferon beta over these results, Tobias Derfuss, MD, and Ludwig Kappos, MD, both of the University Hospital Basel, Switzerland, cautioned in an accompanying editorial.

Controlled clinical trials have shown that interferon beta and other disease-modifying drugs cut down on relapse frequency and related progression of impairment and disability in MS.

“The common but disputed assumption has been that these clinical and radiographic findings in studies limited to 2 to 3 years’ duration translate into long-term benefits, with delay or prevention of long-term disability in patients typically seen in a neurological practice,” the editorial explained, which is key for a disease with an average duration of 30-plus years.

But drug efficacy often isn’t as good in real-world settings with broader patient populations and much longer durations of treatment without the highly structured, supportive follow-up used in trials, Tremlett’s group noted.

The bottom line is that the results call into question the assumption of long-term benefit, which remains unproven, the researchers and editorialists agreed.

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