IMPROVE

Treatment tested

• Interferon beta-1a

  Interferon alpha/beta receptor agonist

Placebo or sham

• Placebo
• Rebif® New Formulation (IFN-beta-1a, RNF)

Other measures (2)

Inclusion Criteria: * Males and females between 18 and 60 years of age * Female subjects must be neither pregnant nor breast-feeding and must lack child-bearing potential, as defined by either: post-menopausal or surgically sterile or use an effective method of contraception for the duration of the study * Have Relapsing Remitting Multiple Sclerosis (RRMS) according to the revised McDonald criteria 2005 * Have brain and/or spinal MRI with findings typical of Multiple Sclerosis (MS) * Have disease duration for more than 12 months * Have disease activity characterized by at least one clinical event and one or more Gadolinium-enhancing MRI lesions within the 6 months prior to randomization * Have score of \<=5.5 on the Expanded Disability Status Scale (EDSS) * Be willing and able to comply with the protocol for the duration of the study * Have given written informed consent prior to any study-related procedure not part of the normal medical practice Exclusion Criteria: * Have any disease other than MS that could better explain his/her signs and symptoms * Have complete transverse myelitis or bilateral optic neuritis * Have received or have used anytime monoclonal antibodies, mitoxantrone, cytotoxic or immunosuppressive therapy (excluding systemic steroids and adrenocorticotrophic hormone [ACTH]), or total lymphoid irradiation * Have received within 3 months prior to baseline any approved disease-modifying therapy for MS, cytokine or anti-cytokine therapy, intravenous immunoglobulin, plasmapheresis, any investigational drug, or experimental procedure * Have received within 30 days prior to baseline oral or systemic corticosteroids or ACTH * Other protocol defined exclusion criteria could apply

General Note: throughout this record, "Rebif® New Formulation" is used for historical and consistency purposes. Objectives: Primary: To evaluate the efficacy of Rebif® New Formulation (Interferon-beta-1a [IFN-beta-1a], RNF), compared to placebo, in subjects with Relapsing Remitting Multiple Sclerosis and active disease by means of Magnetic Resonance Imaging (MRI) at the end of 16 weeks of treatment Secondary: To evaluate the efficacy of RNF by comparing the mean number of combined unique (CU) lesions per scan per subject between the initial 16 weeks of placebo treatment and 24 weeks of RNF treatment in the same subjects, originally randomized to placebo. Primary Endpoints: The primary endpoint is the difference between the number of CU active MRI lesions at Week 16 in the RNF group (Group 1) versus the placebo group (Group 2). Secondary Endpoints: The secondary endpoint is the difference in the mean number of CU active MRI lesions per scan per subject over the following treatment periods: Study Day 1 - Week 16 versus Weeks 17 - 40 for the subjects randomized to Group 2.