By Ian Mason
SAN DIEGO, CA, May 03 (Reuters Health) - Patients with secondary progressive multiple sclerosis who continue to experience relapses should be treated with interferon (IFN) beta-1b, researchers from the US and Europe said at a late-breaking news session here during the 52nd annual meeting of the American Academy of Neurology.
Their statements followed the release of findings that identified differences in results from two major trials of IFN-beta-1b in patients with this form of MS.
A major European study reported 2 years ago in The Lancet demonstrated
a significant reduction in time to disease progression in patients with
secondary progressive MS who received IFN-beta-1b. However, results from
a North American study of IFN-beta-1b in 939 such patients, reported this
week at the San Diego meeting, showed no effect of active treatment on
time to onset of sustained progression of disability, although the researchers
did find significant treatment effects on most other measures.
"We found significant treatment effects on number of relapses, on reduction in the severity of relapses, on reduction in the duration of relapses, on the number of hospitalizations, and on the need for steroid treatments. IFN-beta-1b also reduced the number of new MRI lesions, the area of MRI lesions, the number of new enhancing lesions and the number of new enlarging lesions," reported Dr. David Goodkin, medical director of the University of California at San Francisco/Mount Zion Multiple Sclerosis Center and chair of the steering committee of the North American trial.
Dr. Henry McFarland, chief of the neuroimmunology branch, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, participated in both the European and North American studies. He told meeting attendees that the results supported treatment with interferon early in the course of secondary progressive MS.
"It seems that interferon is more effective in the earlier stage [of secondary progressive MS] which is associated with an inflammatory response. So I think we are beginning to define in more detail the types of patients who should be receiving this treatment," he said.
Both researchers highlighted key differences between the European and North American studies that may have contributed to their respective outcomes. Patients in the North American study showed more advanced disease, characterized by less active inflammatory activity, and may therefore have been less likely to show a measurable response to IFN-beta-1b as measured by the Expanded Disability Status Scale (EDSS).
"The study populations differed in many respects. The European cohort was younger, with shorter duration of disease, and a relapse rate that was approximately twice that of the North American study population. MRI measurement of active disease showed about twice as many enhancing MRI lesions in the European study," Dr. McFarland said.
Interferon-beta-1b was approved in the US in July 1993 and in the EU in November 1995 for the treatment of relapsing-remitting MS. On the strength of the European study results, Betaferon was licensed for the treatment of secondary progressive MS in Europe, Canada and Australia. An application for the secondary progressive MS indication for Betaferon is currently under consideration by the US Food and Drug Administration.
"It is very difficult to predict what the FDA will do, but I would like
to see this drug made available for prescribing to North American [secondary
progressive MS] patients who have relapses. The question of...patients
who no longer have relapses is a more difficult question, and I confess
I do not know the answer," Dr. Goodkin said.