CD52 and B-cell chronic lymphocytic leukemia: Due to its significant cytotoxic effects, alemtuzumab is capable of depleting CD52 positive cells in vivo and has demonstrated significant activity against a number of B cell malignancies, particularly in refractory and relapsed chronic lymphocytic leukemia (CLL) for which it was previously marketed under the trade name Campath®/Campath-1H, as well as other non-malignant hematopoietic disorders [12][13][14].