Rituximab and Alemtuzumab in Treating Older Patients With Progressive Chronic Lymphocytic Leukemia

RATIONALE: Monoclonal antibodies, such as rituximab and alemtuzumab, can block cancer growth in different ways. Some block the ability of cancer cells to grow and spread. Others find cancer cells and help kill them or carry cancer killing substances to them. Giving rituximab together with alemtuzumab may kill more cancer cells. PURPOSE: This randomized phase II trial is studying two different doses of rituximab to compare how well they work when given together with alemtuzumab in treating older patients with progressive chronic lymphocytic leukemia.

OBJECTIVES: Primary * To compare the rate of complete and overall response in elderly patients with progressive chronic lymphocytic leukemia (CLL) treated with one of two doses of rituximab combined with alemtuzumab to determine if the use of modified-dose rituximab significantly affects outcome. Secondary * To monitor and assess toxicity of these regimens. * To determine the overall and progression-free survival, time to clinical response, time to next treatment, and duration of response in patients treated with these regimens * To assess the correlation between risk stratification prognostic markers (i.e., CD38, ZAP-70, fluorescent in situ hybridization (FISH), and IgVH mutation) and clinical outcome. * To assess response to these regimens using both the 1996 National Cancer Institute Working Group (NCI-WG 96) criteria and an expanded definition of response for patients in complete remission, including immunohistochemical examination of the bone marrow and sensitive flow cytometry (4-6 color) of blood for minimal residual disease and computed tomography (CT) scans for residual adenopathy. * To determine the mechanism of action of rituximab and alemtuzumab and to determine mechanisms of resistance of a subpopulation of CLL cells to these drugs. OUTLINE: This is a multicenter study. Patients are stratified according to FISH risk (low \[13q14-\] vs intermediate \[12+, no abnormality, all other abnormalities\] vs high \[17p13-,11q22-\]). Patients are randomized to 1 of 2 treatment arms. * Arm A: Patients receive alemtuzumab subcutaneously (SC) on days 1-3, 6, 8, 10, 13, 15, 17, 20, 22, 24, 27, 29, and 31 and standard-dose rituximab intravenously (IV) on days 8, 15, 22, and 29 in cycle 1 (33-day cycle). In cycle 2 and subsequent cycles (28-day cycle), patients receive alemtuzumab SC on days 1, 3, 5, 8, 10, 12, 15, 17, 19, 22, 24, and 26 and standard-dose rituximab IV on days 3, 10, 17, and 24. Treatment repeats every 28 days for up to 3 cycles. * Arm B: Patients receive alemtuzumab as in arm A. Patients also receive low-dose rituximab IV on days 6, 8, 10, 13, 15, 17, 20, 22, 24, 27, 29, and 31 in cycle 1 and on days 1, 3, 5, 8, 10, 12, 15, 17, 19, 22, 24, and 26 in cycless 2 and 3. Treatment repeats every 28 days for up to 3 cycles. Blood and bone marrow samples are collected periodically for cytogenetic and biomarker analysis. Alemtuzumab dose for Cycle 1 Week 1 of both Arms A and B requires a 'dose ramp' (3 mg day 1, 10 mg day2, and 30 mg day 3 of cycle 1). After completion of study therapy, patients are followed up periodically for 5 years.