Interferon Beta-1b for the Treatment of Primary Progressive Multiple Sclerosis

To investigate, during the 5-year period without treatment after termination of a 2-year clinical trial of interferon beta-1b for the treatment of primary progressive multiple sclerosis, differences in the evolution of clinical variables and magnetic resonance imaging results between trial arms and to investigate correlations between in-trial changes in Multiple Sclerosis Functional Composite (MSFC) score and magnetic resonance imaging variables and Expanded Disability Status Scale (EDSS) score evolution.Five-year clinical trial follow-up.Clinical Neuroimmunology Unit, Multiple Sclerosis Centre of Catalonia, Autonomous University of Barcelona, Spain. Patients Seventy-three patients received interferon beta-1b or placebo during the trial.After 5 years without treatment, the EDSS and MSFC measures were scored for 63 and 59 patients, respectively. Neuropsychological and magnetic resonance imaging assessments were performed for 59 and 50 patients, respectively.After 5 years without treatment, the interferon beta-1b group had better 9-Hole Peg Test (P = .02) and Word List Generation Test (P .001) scores, and their magnetization transfer ratio measures in the normal-appearing white matter were significantly higher (P = .02, P = .009, and P = .03 for the mean, peak location, and peak height magnetic transfer ratios, respectively). During the entire study period (from trial baseline to assessment at 5 years without treatment), the placebo group showed a greater decrease in brain parenchymal fraction (P = .004). The in-trial increase of lesions correlated with the worsening of the EDSS score during the 5-year period without treatment (P = .004).Modest but beneficial effects of interferon beta-1b on clinical variables and brain atrophy development were observed 5 years after trial termination. Moreover, in-trial lesion activity correlated with EDSS progression after trial termination. Therefore, we provide evidence to consider immunomodulation as a sensible approach to treat primary progressive multiple sclerosis.