Interferon beta-1b and secondary progressive multiple sclerosis: licence extension. Useful, but further assessment...

(1) Interferon beta-1b is now licensed to treat patients with secondary progressive multiple sclerosis. (2) The clinical file that we compiled on this indication, includes a double-blind placebo-controlled trial in which 718 patients were treated for 2-3 years. The trial is methodologically sound. (3) In this trial, interferon beta-1b, at the only dose tested (8 MIU every two days by the subcutaneous route), significantly reduced the progression of the disability linked to the disease. After 2-3 years of treatment the percentage of patients confined to a wheelchair was, in absolute values, 16.7% in the interferon beta-1b group and 24.6% in the placebo group. (4) In this trial the adverse effects linked to interferon beta-1b were already known, i.e. mainly a 'flu-like syndrome at the outset of treatment, and reactions at the injection site. (5) More than a quarter of patients on interferon beta-1b had neutralising antibodies against interferon beta-1b. More follow-up is needed to determine the possible impact of these antibodies on treatment efficacy and on the possible risk of autoimmune diseases. (6) Treatment with interferon beta-1b is still costly.