Background: In the Betaseron/Betaferon in Newly Emerging Multiple Sclerosis for Initial Treatment (BENEFIT) study, interferon beta-1b delayed conversion to multiple sclerosis in patients with a first clinical event and at least 2 clinically silent brain magnetic resonance imaging (MRI) lesions.
Objective: To examine detailed MRI findings from the first 2 years of this trial.
Design: Double-blind, placebo-controlled, randomized, parallel-group, multicenter, phase 3 study.
Setting: Ninety-eight centers worldwide.
Patients: A total of 404 individuals with a first demyelinating event suggestive of multiple sclerosis.
Interventions: Patients were randomized to receive interferon beta-1b, 250 microg subcutaneously every other day, or placebo. After 24 months of treatment or on conversion to clinically definite multiple sclerosis, open-label interferon beta-1b treatment was offered.
Main outcome measures: Reported MRI data from patients completing 2 years of follow-up.
Results: Data were analyzed from 248 patients taking interferon beta-1b and 156 taking placebo. Across 2 years the cumulative number of newly active lesions was lower in patients receiving interferon beta-1b vs placebo (median, 2.0 vs 5.0 [reduction of 60%]; P < .001). This corresponded to lower cumulative numbers of new T2 lesions (median, 1.0 vs 3.0 [reduction of 66%]; P < .001) and new gadolinium-enhancing lesions (median, 0.0 vs 1.0; P < .001) in patients receiving interferon beta-1b vs placebo. From screening to month 24, T2 lesion volume decreased and was more pronounced in patients receiving interferon beta-1b (P = .02).
Conclusions: Interferon beta-1b treatment had a robust effect on MRI measures, supporting its value as an early intervention in this patient group. This effect was maintained despite including patients who switched from placebo to interferon beta-1b in the active treatment group. Trial Registration clinicaltrials.gov Identifier: NCT00185211.