REsPonse to Interferon-Alpha in InterfeRon-β Neutralizing Antibody Positive Multiple Sclerosis Patients

Inclusion Criteria: * The subject must give written informed consent prior to any study related activities * Subject age must be between 18 and 55 (both included) * The subject must have MS according to McDonald criteria * The subject must have disability equivalent to EDSS of 5.5 or less * The subject must have been treated with any IFN-β preparation for at least 12 months at any time * The subject must have been shown to be NAb positive and without no in vivo mRNA MxA response within the last 12 months * The subject must be prepared and considered able to follow the protocol Exclusion Criteria: * The subject must not have conditions that might give rise to similar symptoms as MS * The subject must not have received any immunomodulatory or immunosuppressive treatment (other than IFN-β or glatiramer acetate) 6 months prior to the screening visit * The subject must not have received mitoxantrone, cyclophosphamide, treosulphane, natalizumab, daclizumab, rituximab, alemtuzumab, cladribine, or any experimental therapy at any time * The subject must not have undergone previous total body irradiation, total lymphoid irradiation, stem cell treatment, autologous bone marrow transplantation or allogenic bone marrow transplantation. * The subject must not have received treatment with glucocorticoids or ATCH later than 2 month prior to the screening visit * The subject must not have alcohol and drug dependency * The subject must not have cardiac or renal insufficiency * The subject must not have any systemic disease that can influence the subject's safety or compliance * Subjects may be male or female. Women of child-bearing potential must be sexually inactive or practice a medically acceptable method of birth control. Acceptable methods include oral contraceptive, contraceptive patch, long-acting injectable contraceptive, or double-barrier method (condom or IUD with spermicide) * The subject must not have known or suspected allergy to IFN-α * The subject must not have participated in any other study within 3 months prior to the screening visit