Study to Evaluate Efficacy, Safety, and Tolerability of IMU-838 in Patients With Progressive Multiple Sclerosis

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 IMU838 in adult patients with PMS. The study will consist of the following periods: Screening Period: Approximately 28 days Main Treatment Period: Up to 120 weeks (approximately 2 years) Open Label Extension Period: Up to approximately 8 years