Methodology; The investigators plan to conduct a 5 years study to search for the best predicting factors at the beginning of treatment and after 2 years. In this grant application the investigators will perform a multivariate analysis of clinical, MRI, and biological markers (neutralizing antibody, DNA, and mRNA expression) from baseline to 2 years. For feasibility reasons, long term follow up (5 years) and proteomics study will be performed in a second stage.