Safety and Efficacy Study of MIS416 to Treat Secondary Progressive Multiple Sclerosis

The primary objectives of the study are to: 1. Determine the efficacy of MIS416, relative to placebo, when administered repeatedly via weekly intravenous (IV) administration to subjects with Secondary Progressive Multiple Sclerosis, as assessed by its effect on measures of neuromuscular function. 2. Determine the safety and tolerability of a weekly regimen of MIS416. The secondary objectives of the study are to: 1. Determine the effect of MIS416 on disease activity and neurodegeneration by assessing changes in Magnetic Resonance Imaging (MRI) markers including lesions, whole brain atrophy (WBA) and Magnetization Transfer Ratio (MTR). 2. Determine the effect of MIS416 on Patient Reported Outcomes (PRO) related to disability and health status. 3. Assess, in a subset of subjects, the pharmacodynamic (PD) effects of MIS416, including effects on serum, Peripheral Blood Mononuclear Cell (PBMC), and Cerebral Spinal Fluid (CSF) cytokine/chemokine levels and expression patterns.