Effect of interferon-beta 1b on magnetic resonance imaging outcomes in secondary progressive multiple sclerosis: Results of a European multicenter, randomized, double blind, placebo-controlled trial

A randomized placebo-controlled trial of interferon-beta 1b was performed o n 718 patients with secondary progressive multiple sclerosis with follow-up of up to 3 years. In addition to clinical variables, serial magnetic reson ance imaging (MRI) studies were performed to determine the effect of treatm ent on the pathological evolution of the disease. All patients eligible for MRT had annual proton density/T2-weighted brain scans from which total les ion volume was measured and the number of new and enlarging lesions noted. A subgroup of 125 patients also underwent monthly gadolinium-enhanced and p roton density/T2-weighted brain MRI from months 0 to 6 and 18 to 24 to dete rmine the effect of treatment on the frequency of new lesion activity, defi ned as new enhancing lesions and new/enlarging T2 lesions not enhancing wit h gadolinium. The difference in total lesion volume between treatment group s was highly significant. In the placebo group, there was an increase of 15 % from baseline to last scan, whereas in the interferon-beta 1b group, a re duction of 2% was seen. Within the placebo group, there was a significant y ear-on-year increase in total lesion volume, with a mean increase of 16% at year 3 compared with baseline. In the treated group, there was a significa nt reduction at year 1 (4%) and year 2 (5%) compared with baseline; the 2% decrease at year 3 was not significant. The number of new or enlarging prot on density/T2 lesions was also significantly reduced by treatment. In the f requent MRI subgroup, treatment was associated with a significant 65% reduc tion in new lesion activity between months 1 and 6, and 78% reduction from months 19 to 24. Interferon-beta 1b has a substantial and sustained effect on reducing the accumulation of new inflammatory disease foci in secondary progressive MS. This therapeutic mechanism may contribute to the positive c linical benefits of treatment on the progression of sustained neurological disability and relapse activity that were also identified in this trial.