Defining and scoring response to IFN-β in multiple sclerosis

The advent of a large number of new therapies for multiple sclerosis (MS) warrants the development of tools that enable selection of the best treatment option for each new patient with MS. Evidence from clinical trials clearly supports the efficacy of IFN-β for the treatment of MS, but few factors that predict a response to this drug in individual patients have emerged. This deficit might be due, at least in part, to the lack of a standardized definition of the clinical outcomes that signify improvement or worsening of the disease. MRI markers and clinical relapses have been the most widely studied short-term factors to predict long-term response to IFN-β, although the results are conflicting. Recently, integrated strategies combining MRI and clinical markers in scoring systems have provided a potentially useful approach for the management of patients with MS. In this Review, we focus on the many definitions of clinical response to IFN-β and explore the markers that can be used to predict this response. We also highlight advantages and limitations of the existing scoring systems in light of future expansion of these models to biological markers and to other classes of emerging therapies for MS.