A single-arm, open-label study of alemtuzumab in treatment-refractory patients with multiple sclerosis

Background: Alemtuzumab (CD52-specific humanized monoclonal antibody) was found to be an effective therapy for treatment-naive patients with relapsing-remitting multiple sclerosis. Objective: Evaluate alemtuzumab's effects in patients with treatment-refractory relapsing-remitting multiple sclerosis. Methods: Forty-five relapsing-remitting multiple sclerosis patients who experienced 2 relapses during 2 years prior to the study entry whilst receiving interferon therapy were administered 24 mg IV alemtuzumab/day for 5 days at baseline and 3 days 12 months later. Patients received premedication with 1 g IV methylprednisolone on days 1-3 at both times. Results: After 2-year follow-up, the annualized relapse rate was reduced by 94% compared to pre-treatment levels, from 1.6 (2 years prior to treatment) to 0.17 for the 2 years following (P < 0.0001). Moreover, 86% of patients showed stable or improved scores on the Expanded Disability Status Scale, and only 1 experienced an increase in disability lasting 6 months. The majority (70-88%) showed stable or improved leg, arm and cognitive function as measured by the Multiple Sclerosis Functional Composite. Serious adverse events observed in single patients were transient neutropenia and pneumonia, pulmonary emboli and deep vein thrombosis. Five patients developed clinical thyroid disorders but no opportunistic infections or cases of immune thrombocytopenic purpura were observed. Conclusions: Alemtuzumab effectively reduced relapse rates and improved clinical scores in patients with active relapsing-remitting multiple sclerosis not controlled by interferon therapy.