April 19, 2002
By Jill Stein
Special to DG News
New findings indicate that once weekly intramuscular Avonex (interferon beta-1a) at doses of 30 µg or 60 µg are equally in effective in treating relapsing multiple sclerosis.
The results, presented at the 54th Annual Meeting of the American Academy of Neurology, (AAN) also indicate that the efficacy of the two doses is sustained after four years of treatment.
The trial's principal investigator was Dr. Ludwig Kappos, with University Hospitals in Basel, Switzerland.
For the study, patients with relapsing multiple sclerosis (MS) who had completed at least three years of treatment as part of the European Interferon Beta-1a Dose-Comparison Study were given the option to continue double-blind treatment with either 30 µg or 60 µg intramuscularly once weekly until the completion of the trial. Of 608 patients who completed the first part of the study, 491 subjects had four-year follow-up and 446 completed four years of treatment and follow-up.
The 30 µg and 60 µg treatment groups were similar with respect to age, gender, race, duration of MS, Expanded Disability Status Scale score, magnetic resonance imaging measures of disease activity, and pre-study exacerbation rates.
Analysis of four-year data was conducted on several end points: cumulative rate of sustained disability progression, extent of change in Expanded Disability Status Scale score, relapse rate, and percentage of relapse-free patients, use of intravenous steroids, and neutralizing antibody (NAB) formation.
Results showed that the two study doses were equally effective for up to four years, and there were no significant differences between doses on any of the clinical end points.
Overall, 52 percent of patients in the 30 µg group were free of disability progression at four-year follow-up compared with 57 percent in the 60 µg group (rate ratio, 0.89; 95 percent confidence interval [CI], 0.72 to 1.11; p = 0.32). The percentage of relapse-free patients was 18 and 19 percent in the two groups, respectively (p=0.85).
The incidence of patients who were NAB formation at any time during the study was 2.3 percent in the 30 µg group and 5.8 percent in the 60 µg group (p=0.011).
Dr. Kappos said that the investigation is the largest long-term study ever conducted in MS without patient re-randomization. He also noted that the results concur with the effects of interferon beta-1a on sustained disability progression observed in the pivotal phase III trial.
The trial was supported by Biogen, Inc.
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