Limited data on the effect of ß-interferon treatment on PPMS exists. Only two single-centre placebo controlled trials of interferon beta have been done. Based on this review, the included studies showed that ß-interferon treatment was not associated with reduced disability progression in PPMS patients. However, the trial population was too small to allow definitive conclusions on the efficacy of ß-interferon therapy in PPMS patients. Larger research studies need to be done in patients with PPMS in order to clarify whether ß-interferon is effective in this population.
Interferon beta-1a in primary progressive MS: an exploratory, randomized, controlled trial.
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.
                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.
                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).
                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.