A Phase II Study Comparing Low- and High-Dose Alemtuzumab and High-Dose Rebif® in Patients With Early, Active Relapsing-Remitting Multiple Sclerosis

The aims of MS therapy are to prevent the progression of disease and accumulation of long-term disability. The hypothesis underlying this study was that aggressive treatment of inflammation in the brain early in the course of MS would protect the participant from disease progression and accumulating disability. This protocol compared two different doses of alemtuzumab and high-dose, high frequency of SC interferon beta-1a to evaluate the safety profiles of the respective treatments and to evaluate efficacy in terms of: * Slowing the sustained accumulation of disability in participant with MS; * Reducing the frequency of relapses experienced by participant with MS; and * Reducing the harmful effects of MS on the brain, as assessed by magnetic resonance imaging (MRI) Participants who received alemtuzumab during the initial 36-month treatment period may have been eligible for re-treatment with alemtuzumab in the extension study CAMMS03409 (NCT00930553) to evaluate: * How long the effects of prior alemtuzumab treatment lasted; * If additional treatments with alemtuzumab continued to reduce the effects of MS; and * What kind of side effects participants experienced upon retreatment with alemtuzumab