Interferon β-1a in primary progressive MS -: An exploratory, randomized, controlled trial

Background: Patients with primary progressive MS have atypical clinical and MRI characteristics and have been excluded from most therapeutic trials. The authors report a randomized, controlled trial restricted to primary progressive MS. Methods: Fifty subjects were randomized to weekly IM interferon beta-1a 30 mug, 60 mug, or placebo for 2 years. The primary endpoint was time to sustained progression in disability. Secondary outcomes included the timed 10-meter walk, nine-hole peg test, and on MRI, T2 and T1 brain lesion loads and brain and spinal cord atrophy. Results: The 30-mug dose of interferon beta-1a was well tolerated, but the 60-mug dose caused severe Rulike reactions and raised liver enzymes. No treatment effect was seen on the primary endpoint. Subjects on interferon beta-1a 30 mug had a lower rate of accumulation of T2 lesion load than controls (p = 0.025); subjects on 60 mug had a greater rate of ventricular enlargement than controls (p = 0.025). Conclusions: This study has demonstrated that interferon beta-1a 30 mug was well tolerated, identified useful outcome measures, but showed no efficacy on the primary outcome measure or on most of the secondary outcome measures.