Natalizumab is a monoclonal antibody thought to act by inhibiting the migration of leukocytes into the central nervous system leading to a reduction of inflammation and demyelination.
The efficacy of natalizumab monotherapy was assessed in a two-year study1 involving 942 patients with relapsing multiple sclerosis who had experienced at least one clinical relapse in the previous 12 months and scored between 0 and 5 on the Kurtzke Expanded Disability Status Scale (EDSS).
Patients received treatment by intravenous infusion every four weeks for more than two years; 627 patients were randomly assigned to the natalizumab group (300mg) and 315 to the placebo group. The study evaluated the rate of clinical relapse at one and two years and the rate of sustained progression of disability, using EDSS, at two years.
After two years of treatment there was a relative risk reduction in the rate of relapse of 68 per cent for patients treated with natalizumab compared to placebo. The risk of sustained disability progression (for 24 weeks) was reduced by 54 per cent in patients treated with natalizumab compared to placebo.2 Natalizumab also showed significant effects on secondary end points, including a 92 per cent reduction in gadolinium enhancing lesions.1
Overall adverse events were similar between the placebo and treatment groups. However, fatigue and allergic reactions were significantly more common with natalizumab compared to placebo.
1. Polman C, Paul M, O'Connor W et al. A randomised, placebo-controlled trial of natalizumab for relapsing multiple sclerosis. NEJM 2006: Vol 354(9); 899–910.
2. Tysabri Summary of Product Characteristics. Biogen Idec Nov 2007.
Further information: Biogen Idec 01628 501000