This study will be a multicenter, randomized, double-blind, placebo-controlled study with a blinded Main Treatment Period (MT) and an Open Label Period (OLE) to evaluate the efficacy, safety, and tolerability of IMU-838 in adult patients with RMS. The study will consist of the following periods:
Screening Period: Approximately 28 days Main Treatment Period: Up to 72 weeks (approximately 15 months) Open Label Extension Period: Up to approximately 8 years