Safety and Efficacy of Natalizumab in the Treatment of Multiple Sclerosis

Inclusion criteria

• Diagnosis of MS, as defined by McDonald et al., criteria # 1-4 (McDonald et al., 2001)
• Between the ages of 18 and 50, inclusive.
• Baseline EDSS score between 0.0 and 5.0, inclusive.
• Have experienced at least one relapse within the 12 months prior to randomization.
• Cranial MRI scan demonstrating lesion(s) consistent with MS.
• Have given written informed consent to participate in the study.

Exclusion criteria

• Primary progressive, secondary progressive, or progressive relapsing MS.
• MS relapse has occurred,in the opinion of the investigator, within 50 days prior to randomization and/or the subject has not stabilized from a previous relapse.
• A clinically significant infectious illness within 30 days prior to randomization.
• History of, or abnormal laboratory results indicative of any significant cardiac, endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, gastrointestinal, dermatologic, psychiatric, renal and/or other major disease, that in the opinion of the investigator, would preclude the administration of a recombinant humanized antibody immunomodulating agent for 116 weeks.
• History of severe allergic or anaphylactic reactions or known drug hypersensitivity.
• Unable to perform the Timed 25-foot Walk, 9HPT, and PASAT 3.
• Abnormal blood tests performed at the Screening Visit.