MAGNETIC-RESONANCE STUDIES OF INTRAMUSCULAR INTERFERON BETA-1A FOR RELAPSING MULTIPLE-SCLEROSIS

The Multiple Sclerosis Collaborative Research Group trial was a double -blind, randomized, multicenter, phase III, placebo-controlled study o f interferon beta-1a (IFN beta-1a; AVONEX) in relapsing forms of multi ple sclerosis. Initial magnetic resonance imaging results have been pu blished; this report provides additional results. Treatment with IFN b eta-1a, 30 mu g once weekly by intramuscular injection, resulted in a significant decrease in the number of new, enlarging, and new plus enl arging T2 lesions over 2 years. The median increase in T2 lesion volum e in placebo and IFN beta-1a patients was 455 and 152 mm(3), respectiv ely, at 1 year and 1,410 and 628 mm(3) at 2 years, although the treatm ent group differences did not reach statistical significance. For acti ve patients, defined as those with gadolinium enhancement at baseline, the median change in T2 lesion volume in placebo and IFN beta-1a pati ents was 1,578 and -12 mm(3) and 2,980 and 1,285 mm(3) at 1 and 2 year s, respectively. Except for a minimal correlation of 0.30 between rela pse rate and the number of gadolinium-enhanced lesions, correlations b etween MR and clinical measures at baseline and throughout the study w ere in general poor. Once weekly intramuscular IFN beta-1a appears to impede the development of multiple sclerosis lesions at an early stage and has a favorable impact on the long-term sequelae of these inflamm atory events as indicated by the slowed accumulation of T2 lesions.