NEOPLASIA Brief report Expression of CD52 on plasma cells in plasma cell proliferative disorders

Multiple myeloma (MM) and primary sys-temic amyloidosis (AL) remain incurable disorders, and new treatments targeted to the malignant plasma cells are needed. Alemtuzumab is a humanized monoclo-nal antibody to CD52 and has activity in chronic lymphocytic leukemia. We exam-ined the CD52 expression on CD45 and CD45 plasma cell populations to evalu-ate the potential for using alemtuzumab for these disorders. Bone marrows from 61 patients (29 AL, 23 MM, and 9 MGUS [monoclonal gammopathies of undeter-mined significance]) were studied using 3-color (CD38/45/52) flow cytometry. Among those with MGUS, MM, and AL, 67%, 52%, and 35%, respectively, were positive for CD52 expression. The CD52 expression was predominantly confined to the clonal CD38/CD45 plasma cell fraction with median expression of 68%, 88%, and 82 % in MGUS, MM, and AL, respectively, compared with 18%, 6%, and 9 % among the CD45 plasma cell popula-tion. Clinical trials are warranted in these diseases to learn the therapeutic benefit of anti-CD52 immunotherapy. (Blood