Interferon β-1a in primary progressive MS

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 microg, 60 microg, 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- microg dose of interferon beta-1a was well tolerated, but the 60- microg dose caused severe flulike reactions and raised liver enzymes. No treatment effect was seen on the primary endpoint. Subjects on interferon beta-1a 30 microg had a lower rate of accumulation of T2 lesion load than controls (p = 0.025); subjects on 60 microg had a greater rate of ventricular enlargement than controls (p = 0.025). CONCLUSIONS: This study has demonstrated that interferon beta-1a 30 microg was well tolerated, identified useful outcome measures, but showed no efficacy on the primary outcome measure or on most of the secondary outcome measures.