In this article, the researchers looked at when the clinical effects of natalizumab become apparent in a phase II study, and the annualised relapse rates per 3-month period, and the time to first relapse in the phase III AFFIRM study (a randomised, double-blind, placebo-controlled trial, natalizumab vs. placebo) and in the multinational Tysabri Observational Program (TOP, an ongoing 10-year open-label, multinational, multicenter, prospective observational study looking at the long-term safety and efficacy of natalizumab). In AFFIRM, natalizumab had a significant effect on annualised relapse rate within three months of initiating therapy and reductions were sustained over the 2-year study period.
This was combined with the MRI findings of the phase II study, in which reductions in the mean number of new gadolinium-enhancing lesions were apparent after one month and remained reduced as long as treatment was continued. In TOP, rapid reduction in annualised relapse rate also occurred. Therefore, natalizumab resulted in rapid, sustained reductions in disease activity in both AFFIRM and in clinical practice, and this reduction occurred within the first three months, even in patients with more active disease, providing both short- and long-term benefits.
Authors: Kappos L, O'Connor PW, Polman CH
Source: J Neurol. 2013 Jan 5. [Epub ahead of print]
Read the abstract