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.