CAMMS223 Trial Investigators (2008) Alemtuzumab vs. interferon beta-1a in early multiple sclerosis. N Engl J Med 359: 1786–1801

Immunotherapy might only affect long-term disability in multiple sclerosis (MS) if administered early in the disease course. A phase II, blinded trial investigated the efficacy of alemtuzumab, a humanized monoclonal antibody that causes prolonged T-cell depletion, in patients with early relapsing–remitting MS.

Previously untreated patients who had developed relapsing–remitting MS no more than 36 months earlier were randomly assigned to receive alemtuzumab 12 mg or 24 mg daily, or to 44 µg interferon β1a (IFN-β1a) three times a week, for 36 months.

The risk of sustained disability was 71% lower and the rate of relapse was 74% lower in the 223 patients who were receiving alemtuzumab than in the 111 individuals on IFN-β1a. In addition, the mean disability on a 10-point scale improved by 0.39 of a point in the alemtuzumab group but worsened by 0.38 of a point in the IFN-β1a group (P <0.001). The incidence of infection and of thyroid associated adverse events was higher in patients who received alemtuzumab than in those on IFN-β1a. Immune thrombocytopenic purpura developed in six (2.8%) patients in the alemtuzumab group, one of whom died, and in one (0.9%) patient in the IFN-β1a group.

Alemtuzumab is effective at preventing relapse and at limiting the accumulation of disability in MS but is associated with autoimmune complications. The authors point out that most patients with early relapsing–remitting MS are young and have little disability; it remains to be confirmed whether it is reasonable to treat such individuals with alemtuzumab given the severe adverse effects.