Tumefactive demyelination following treatment for relapsing multiple sclerosis with alemtuzumab

Alemtuzumab, a humanized anti-CD52 monoclonal antibody that results in profound depletion and repopulation of mature lymphocytes, is a highly efficacious therapy for active, relapsing-remitting multiple sclerosis (RRMS). In 2 phase 3 clinical trials of alemtuzumab, Comparison of Alemtuzumab and Rebif Efficacy in Multiple Sclerosis (CARE-MS) I and II, 14% and 23% of patients treated with alemtuzumab had a clinical relapse within the first 12 months, respectively.1,2