A Study to Characterize Subcutaneous or Intravenous Alemtuzumab in Patients With Progressive Multiple Sclerosis

Inclusion criteria: * Male or female adults with a diagnosis of Multiple Sclerosis (MS) based on 2010 revision of McDonald criteria. * Diagnosis of progressive MS including primary progressive MS and secondary progressive MS. * Age ≥18 years. * Signed informed consent form. * Covered by a health insurance system where applicable, and/or in compliance with the recommendations of the national laws in force relating to biomedical research. * Not under any administrative or legal supervision. Exclusion criteria: * Patients with relapsing remitting MS. * Any prior treatment with alemtuzumab or other anti-CD52 antibodies. * Treatment with natalizumab in the 4 months prior to Study Visit 1. * Progressive multifocal leukoencephalopathy (PML), or any clinical or imaging signs possibly indicative of undiagnosed PML. Particular vigilance is needed for patients with prior natalizumab exposure, even if the last exposure was more than 4 months prior to Study Visit 1. * Treatment with methotrexate, azathioprine, or cyclosporine in the past 6 months. * Treatment with mitoxantrone, cyclophosphamide, cladribine, rituximab, or any other immunosuppressant or cytotoxic therapy (other than steroids) in the last 12 months, or determined by the treating physician to have residual immune suppression from these treatments. * Treatment with glatiramer acetate or interferon beta in the past 4 weeks. * Treatment with fingolimod within the past 2 months. * Treatment with dimethyl fumarate in the past 4 weeks. * Treatment with teriflunomide within the past 12 months unless the patient has completed an accelerated clearance with cholestyramine or activated charcoal. * Any known contraindications to the symptomatic therapy used in the infusion management guidance for this study. * Hypersensitivity or contraindication to acyclovir. * History of a hypersensitivity reaction other than localized injection site reaction to any biological molecule. * If female, pregnancy (defined as positive β-HCG blood test) or lactating or breast-feeding. * Current participation in another investigational interventional study. * Any significant change in chronic treatment medication (ie, new chronic medication) within 14 days before inclusion. * An investigational medicinal product within 3 months or 5 half-lives, whichever is longer, before study inclusion. * Total lymphocyte or CD3+ counts are below normal limits at screening. If abnormal cell count(s) return to within normal limits, eligibility may be reassessed. * Live, attenuated vaccine within 3 months prior to the randomization (Day 1) visit, such as varicella-zoster, oral polio, rubella vaccines. * Any clinically relevant findings in the physical examination, medical history, or laboratory assessments which would compromise the safety of the patient. * Women of childbearing potential not protected by highly-effective method(s) of birth control and/or who are unwilling or unable to be tested for pregnancy. * Latent or active tuberculosis infection, verified by testing as per local practice. * Infection with human immunodeficiency virus (HIV). * Known Hepatitis B (HBV) or Hepatitis C (HCV) infection. * Active infection, eg, deep tissue infection, that the Investigator considers sufficiently serious to preclude study participation. * Prior history of invasive fungal infections. * Any patient who, in the judgment of the Investigator, is likely to be noncompliant during the study, or unable to cooperate because of a language problem or poor mental development. * Any patient in the exclusion period of a previous study according to applicable regulations. * Any patient who cannot be contacted in case of emergency. * Any patient who is the Investigator or any subinvestigator, research assistant, pharmacist, study coordinator, other staff or relative thereof directly involved in the conduct of the protocol. The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.