CARE-MS II

Treatment tested

• Alemtuzumab

  CAMPATH-1 antigen inhibitor

• Interferon beta-1a

  Interferon alpha/beta receptor agonist

Compared with

• Interferon beta-1a

  Interferon alpha/beta receptor agonist

Other measures (5)

Inclusion Criteria: * Signed informed consent form (ICF) * Age 18 to 55 years (inclusive) as of the date the ICF was signed * Diagnosis of MS per update of McDonald criteria * Onset of MS symptoms (as determined by a neurologist; could be retrospectively) within 10 years of the date the ICF was signed * Expanded Disability Status Scale (EDSS) score 0.0 to 5.0 (inclusive) at Screening * Greater than or equal to (>=) 2 MS attacks (first episode or relapse) occurring in the 24 months prior to the date the ICF was signed, with >=1 attack in the 12 months prior to the date the ICF was signed, with objective neurological signs confirmed by a physician, nurse practitioner, or other Genzyme-approved health-care provider and the objective signs could be identified retrospectively * >=1 MS relapse during treatment with a beta interferon therapy or glatiramer acetate after having been on that therapy for >=6 months within 10 years of the date the ICF was signed * MRI scan demonstrating white matter lesions attributable to MS and meeting at least 1 of the following criteria, as determined by the neurologist or a radiologist: >=9 time constant 2 (T2) lesions at least 3 millimeter (mm) in any axis; a gadolinium- (Gd-) enhancing lesion at least 3 mm in any axis plus >=1 brain T2 lesions; and a spinal cord lesion consistent with MS plus >=1 brain T2 lesion Exclusion Criteria: * Received prior therapy with alemtuzumab * Current participation in another clinical study or previous participation in CAMMS323 (Comparison of Alemtuzumab and Rebif Efficacy in Multiple Sclerosis, CARE-MS I) * Treatment with natalizumab, methotrexate, azathioprine, or cyclosporine in the past 6 months. Participants who received one of these medications more than 6 months before the date the ICF was signed were eligible for study entry if approval was granted by Genzyme * Any progressive form of MS * History of malignancy (except basal skin cell carcinoma) * CD4 +, CD8 +, CD19 + (that is, absolute CD3 + CD4 + , CD3 + CD8 + , or CD19 + /mm 3 ) count, absolute neutrophil count less than (\<) lower limit of normal (LLN) at screening; if abnormal cell count(s) returned to within normal limits (WNL), eligibility could be reassessed * Known bleeding disorder (for example, dysfibrinogenemia, factor IX deficiency, hemophilia, Von Willebrand's disease, disseminated intravascular coagulation, fibrinogen deficiency, or clotting factor deficiency) * Significant autoimmune disease including but not limited to immune cytopenias, rheumatoid arthritis, systemic lupus erythematosus, other connective tissue disorders, vasculitis, inflammatory bowel disease, severe psoriasis * Presence of anti-thyroid stimulating hormone (TSH) receptor (TSHR) antibodies (that is, above the LLN) * Active infection or at high risk for infection

The purpose of this study was to establish the efficacy and safety of two different doses of alemtuzumab (Lemtrada™) as a treatment for relapsing-remitting multiple sclerosis (MS), in comparison with subcutaneous interferon beta-1a (Rebif®). The study enrolled participants who had received an adequate trial of disease-modifying therapies but experienced at least 1 relapse during prior treatment, and who met a minimum severity of disease as measured by magnetic resonance imaging (MRI). Participants had monthly laboratory tests and comprehensive testing every 3 months.