Natural interferon-beta treatment of relapsing-remitting and secondary-progressive multiple sclerosis patients. A two-year study

OBJECTIVES: To evaluate clinical and MRI effects of natural interferon beta treatment in both relapsing‐remitting (RR) and secondary‐progressive (SP) multiple sclerosis patients. MATERIAL AND METHODS: A double‐blind, randomized trial of natural interferon beta (nIFN‐beta) in 58 ambulatory patients with RR and 40 with SP multiple sclerosis. Forty‐nine patients (29 RR and 20 SP) were treated with intramuscular nIFN‐beta6 MIU three times a week for 24 months and 49 control patients were treated with placebo. RESULTS: Primary clinical endpoints were differences in exacerbation rates and proportion of patients remaining exacerbation‐free. There were no significant baseline differences between the treated and placebo groups. In the treated RR group a significant reduction in exacerbation rate, an increase in the probability of remaining exacerbation‐free, and an improvement in mean EDSS were found at 24 months. MRI activity and total lesion burden were significantly reduced in treated RR patients. In the SP group, nIFN‐beta produced a significant reduction in EDSS score, a significant reduction in active lesion number, a marginally significant favourable difference in total lesion burden but no significant effect on the number of gadolinium‐enhancing lesions. Side effects were transient and mild in treated patients. CONCLUSIONS: These observations confirm that nIFN‐beta is a promising and well‐tolerated treatment for either RR or SP MS patients.