REPORT FROM THE 63rd ANNUAL MEETING OF THE AMERICAN ACADEMY OF NEUROLOGY (AAN), HONOLULU, HAWAII, APRIL 9-16, 2011 – CAMMS23 was a phase II trial comparing alemtuzumab, a monoclonal antibody that targets CD52 lymphocytes, with subcutaneous beta-interferon-1a (CAMMS223 Trial Investigators et al. N Engl J Med 2008; 359: 1786-1801; free full text at www.nejm.org/doi/full/10.1056/NEJMoa0802670). Alemtuzumab dosing groups received either 12 or 24 mg IV x 1 cycle/year. While alemtuzumab appeared to be more effective than beta-interferon (annualized relapse rate 0.10 vs. 0.36), alemtuzumab was suspended after three patients developed immune thrombocytopenia purpura (ITP).