Alemtuzumab levels according to dose and presence of CD52-expressing tumor. (A) Scatter plots show peak alemtuzumab levels in patients according to dose group and presence (open symbols) or absence (closed symbols) of CD52-expressing tumor at the time of transplantation. (B) Examples of individual alemtuzumab levels according to dose and time from transplantation in patients with CD52-expressing tumor (CLL) or no tumor. Dotted line represents limits of detection (37.5 ng/mL) for enzyme-linked immunoabsorbent assay.