As B cells are thought to influence the pathogenesis of multiple sclerosis (MS), through antigen presentation, auto antibody production or cytokine secretion, a number of treatment options have focused on manipulating the function of B cells. This study explored the efficacy and safety of Ocrelizumab, a humanized monoclonal antibody that selectively depletes CD20-expressing B cells.

Subjects were 18 to 55 years of age with a diagnosis of primary, progressive MS. The patients were randomized to receive Ocrelizumab, 600 mg every 24 weeks, or a placebo for a minimum of five doses (120 weeks). All patients received IV methylprednisolone at 100 mg before infusion.

The primary endpoint was the percentage of patients with disability progression, using the Expanded Disability Status Scale (EDSS). Secondary endpoints included change from baseline to week 120 in performance on the timed 25-foot walk, change in the total volume of brain lesions on T2-weighted MRI, change in the Physical Component Summary score of the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), Version 2, and change in brain volume from week 24 to week 120.

The percentages of patients with 24-week confirmed disability progression were 29.6% in the treatment group and 35.7% in the placebo group (P＝0.04). Significant improvement was noted in the treatment group as compared with the placebo group on the timed 25 foot walk (P＝0.04), with no difference between groups on the SF-36 Physical Component score (P＝0.6). The total volume of hyperintense lesions on T2-weighted images decreased in the treatment group and increased in the placebo group (P<0.001).

This study of patients with primary progressive multiple sclerosis found that Ocrelizumab is associated with lower rates of clinical and MRI progression.