Expression data from whole blood of RRMS patients initiating treatment with intramuscular IFN-β1a (Avonex®) obtained exactly 12 hours after treatment.

Interferon beta (IFN-β) is a first line treatment for patients with relapsing forms of MS, but response to the drug varies and to date there are no biomarkers associated with individual patient response. Whole blood gene expression data from a clinical study of patients initiating treatment with intramuscular IFN-β1a (Avonex®) was comprehensively analyzed for gene signatures distinguishing between good vs. poor responders where the latter were defined by increases in number and size of observed lesions in quantitative imaging over a 6-month period. We observed signatures related to B-cell activation in subject gene expression prior to treatment while T-cell and interleukin signatures were observed in the same subjects immediately after treatment. These signatures form a basis for developing predictors of IFN-β1a response in patients both prior to and after IFN-β1 treatment. Whole blood was obtained from 85 RRMS/CIS precisely 12 hours after injection of intramuscular IFN-β1a (Avonex®) at an initial (characteristic: time point=T0) and 6-month visit (characteristic: time point=T6). Clinical response was measured by quantifying new and enlarging brain lesions on T2-weighted MRI scans at 6 months (T6) compared to baseline (T0). Based on pre-defined MRI criteria, a group of 15 poor responders (characteristic: response=Poor) with 3 or more new or enlarging lesions was identified, and compared with a group of 15 good responders (characteristic: response=Good) selected from the full patient cohort. The remaining patients (characteristic: response=Indeterminate) were not used for the analysis.