Abstract
BACKGROUND: Alemtuzumab is highly effective at treating chronic lymphocytic leukemia (CLL) in bone marrow, which is the usual site of residual disease after fludarabine-based treatment. Eliminating residual disease potentially is associated with longer remission and overall survival. The authors of this report evaluated the ability of subcutaneous alemtuzumab to treat residual disease. METHODS: Patients in partial remission (PR), nodular PR (nPR), or complete remission (CR) who had disease in bone marrow established by 2-color flow cytometry analysis were enrolled and received alemtuzumab 30 mg subcutaneously 3 times weekly for 4 weeks, and patients had the option to self-administer alemtuzumab. Responders were patients in PR who converted to an nPR or a CR, patients in nPR who converted to a CR, and patients in CR who had no evidence of disease on 2-color flow cytometry analysis after treatment. RESULTS: There were 31 patients enrolled, of whom 29 were evaluable, and there were 23 responders (4 of 4 patients who achieved a CR, 8 of 9 patients who achieved an nPR, and 11 of 16 patients who achieved a PR. Nonresponders had significantly lower plasma alemtuzumab levels at the end of treatment. Furthermore, higher plasma alemtuzumab levels at the end of treatment were correlated with a longer response duration. Compared with the results from an historic group that received intravenous alemtuzumab for residual disease, there was a trend toward a higher response rate but a shorter response duration with subcutaneous alemtuzumab. CONCLUSIONS: The current results demonstrated that self-administered, subcutaneous alemtuzumab was safe and active for residual disease and that plasma alemtuzumab levels and real-time minimal residual disease evaluation are important endpoints to monitor in future alemtuzumab consolidation trials.