Use of interferon beta in multiple sclerosis: Rationale for early treatment and evidence for dose- and frequency-dependent effects on clinical response

The current approach to the use of interferon (IFN) beta in the treatment of multiple sclerosis (MS) is, in general, conservative. However, recent findings about early events in MS and data on dose-response relationships with IFN beta indicate that such an approach may be suboptimal. Four lines of evidence suggest that delays in the initiation of therapy with IFN beta may be detrimental: 1) axonal damage secondary to inflammation starts very early in the course of MS; 2) pathological events occurring early in MS are predictive of the future course of the disease; 3) inflammatory activity in relapsing MS is not confined to episodes of clinical impairment, but often starts before the first such episode and generally continues during remissions; and 4) the immune-mediated activity that underlies MS may become more difficult to control as the disease progresses. An early treatment strategy is also supported by data from two recently published clinical studies. In addition, preclinical and clinical results suggest that the beneficial effects of IFN may be dose- and frequency-dependent. Taken together, these findings indicate that treatment with IFN beta should be started as early as possible in the course of MS, and suggest that, in order to maximize patient benefit, the highest possible dose of IFN beta should be chosen.