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Originally published as JCO Early Release 10.1200/JCO.2007.15.7537 on November 10 2008 © 2008 American Society of Clinical Oncology.
Is Alemtuzumab Really the Single Active Agent for Treatment of Chronic Lymphocytic Leukemia?
Department of Hematology-Oncology, Heartland Regional Medical Center, Saint Joseph, MO To the Editor: We read with great interest the article by Hillmen et al1 on first-line therapy for chronic lymphocytic leukemia (CLL) and would like to commend the efforts of the authors, but we have some queries and suggestions. First, regarding patient selection and characteristics, two thirds of the patient population who received alemtuzumab had early-stage (stage 1 or 2) disease with no clear information about their symptoms. No bone marrow examination was performed before the treatment and no computed tomography scans were performed before enrollment onto the study. This can lead to understaging of the patients involved in the study and potential overestimation of the reported benefits of treatment. Second, regarding follow-up evaluations, patients were evaluated by physical examination, laboratory tests, and chest x-rays only. This is most likely considered suboptimal in clinical practice, and can easily lead to overestimation of the benefits of treatment. For example, while assessing disease progression and response, no consideration would be given to organomegaly and abdominal lymphadenopathy unless more imaging studies were performed. Third, regarding outcomes of the different treatments, the results of this study show that alemtuzumab is superior to chlorambucil with regard to progression-free survival (PFS). If we look at the study by Rai et al2 from 2000, PFS for chlorambucil was 14 months versus 20 months for fludarabine, whereas in this study PFS for alemtuzumab was 14.6 months and 11.7 months for chlorambucil. The median time to alternative therapy for alemtuzumab, according to the current study is 23.3 months versus 14.7 months for chlorambucil. In the study by Rai et al, the median time to alternative therapy was 27 months for fludarabine versus 14 months for cholambucil. Although no comparisons should be made across different studies, the reported outcomes seem to favor fludarabine over alemtuzumab. Complete remission rates were reported in 24.2% of patients with alemtuzumab versus 2% with cholambucil. Byrd et al3 reported that 47% of patients with CLL had complete remission with fludarabine and rituxan followed by rituxan alone. This is almost twice the complete response rate reported in the current study. In addition, alemtuzumab is not a benign chemotherapeutic agent, given that 15% of patients had symptomatic cytomegalovirus and 52% of patients had asymptomatic cytomegalovirus infections. Therefore, the conclusion that alemtuzumab is the most active single agent for the treatment of patients with CLL seems too ambitious, and the current alemtuzumab regimen should be compared with studies using at least fludarabine alone or fludarabine and rituxan as a comparative arm. AUTHORS’ DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The author(s) indicated no potential conflicts of interest. NOTES published online ahead of print at www.jco.org on November 10, 2008. REFERENCES
1. Hillmen P, Skotnicki AB, Robak T, et al: Alemtuzumab compared with chlorambucil as first-line therapy for chronic lymphocytic leukemia. J Clin Oncol 25:5616-5623, 2007 2. Rai KR, Peterson BL, Appelbaum FR, et al: Fludarabine compared with chlorambucil as primary therapy for chronic lymphocytic leukemia. N Engl J Med 343:1750-1757, 2000 3. Byrd JC, Peterson BL, Morrison VA, et al: Randomized phase 2 study of fludarabine with concurrent versus sequential treatment with rituximab in symptomatic, untreated patients with B-cell chronic lymphocytic leukemia: Results from Cancer and Leukemia Group B 9712 (CALGB 9712). Blood 101:6-14, 2003
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Copyright © 2008 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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