This is a multicenter, randomized, double-blind, placebo-controlled trial in which qualifying patients will be randomized 2:1 to receive active drug or placebo. Eligible patients must have MS with relapse, have had one or more relapses during the prior 2 years, 1-10 gadolinium (Gd)-enhancing lesions on the Run-in MRI, and an EDSS of 6.5 or less. There are exclusions for certain prior MS treatments and medical / psychiatric conditions. Following a 4-week run-in phase in which patients will have a baseline MRI, patients will enter a 4 week induction phase, during which they will be receive injections weekly (5 doses), then a 32-week maintenance phase during which injections are monthly (8 doses). A final follow-up visit will be conducted 4 weeks after the last injection. The primary efficacy parameter is a summary change score of the mean number of total Gd-enhancing lesions at weeks 36 and 40 minus the mean number for the two baseline scans. Safety monitoring will include AE/SAE reporting, physical exams, vital signs, ECG. CXR, laboratory tests, neurologic evaluations, and systemic hypersensitivity and injection site assessments. All study medications will be administered by study personnel and patients will remain under observation for a minimum of 2 hours post-injection. An independent Data Safety and Monitoring Board will oversee the safety of the trial.