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.
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.
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.
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.