Relevance of the type I interferon signature in multiple sclerosis towards a personalized medicine approach for interferon-beta therapy.

Multiple sclerosis (MS) is the most common inflammatory disease of the central nervous system. The disease is characterized by progressive neurological dysfunction due to demyelination of the nerves, which leads to disability. Currently, no curative therapy is available and patients are subjected to a prolonged course of treatment. Interferon-β (IFNβ) was the first agent to show clinical efficacy in the treatment of MS, and is still the best available therapy. Unfortunately, clinical experience indicates that approximately 40% of the patients do not or only poorly respond to IFNβ treatment. Recent advances revealed the presence of an activated type I IFN pathway in a subset of treatment naïve patients with relapsing remitting MS (RRMS), as shown by the presence of an "IFN signature" and type I IFN bioactivity in the blood of these patients. Evidence exists that quantification of the IFN signature in RRMS is informative as a biomarker to predict the clinical response to IFNβ. In this review we summarize the current evidence of type I IFN activation in RRMS and its clinical relevance.