Treatment of Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (CLL/SLL): DNA Microarray Gene Expression Analysis

Background: * Due to their synergistic action and non-overlapping toxicity profiles, the combination of Rituximab and Fludarabine is the treatment of choice for advanced stage chronic lymphocytic lymphoma (CLL)/small lymphocytic lymphoma (SLL). * As such, we have designed this protocol to better understand the genetic basis of CLL/SLL, to identify predictors of treatment response and to study the molecular effects of Rituximab Fludarabine on the leukemic cells. * A new technology utilizing complementary deoxyribonucleic acid (cDNA) microarrays now permits the simultaneous quantitation of the expression of thousands of genes; this methodology can evaluate defined cellular pathways, and also discover novel genes influencing cell biology. * In addition to improving our understanding of the pathogenesis of CLL/SLL, these molecular studies may identify new therapeutic targets in CLL/SLL, and may help to identify those CLL/SLL patients most likely to respond to the combination of Fludarabine and Rituximab. Objectives: * Evaluate CLL/SLL patients during and following Rituximab Fludarabine chemotherapy for changes in lymphocyte gene expression using DNA microarray analysis. * Evaluate gene expression by DNA microarray analysis of leukemic cells in blood, bone marrow and lymph nodes. Eligibility: * Low, Intermediate or High-Risk Category of CLL/SLL, using the Modified Three- Stage Rai Staging System * Age greater than or equal to 18 years. * Patients must have received no previous cytotoxic or monoclonal antibody therapy. * Eastern Cooperative Oncology Group (ECOG) performance status of 0-2. * Patients must not be pregnant or breast-feeding. * Patients with active autoimmune hemolytic anemia (AIHA)) grade III or higher (transfusion or steroids indicated) or immune thrombocytopenia (ITP) grade III or higher (platelets less than 50,000/microL) shall not be enrolled. * Any patient with a medical condition that requires chronic use of corticosteroids shall not be enrolled. Design: * Patients who do not require treatment will be followed every 3-6 months and will donate cellular products, bone marrow biopsies, bone marrow aspirates and/or lymph nodes for research purposes. * Patients who do require treatment will received the standard dose of the Rituximab monoclonal antibody and the standard dose of Fludarabine for a total of six cycles. In the first cycle, Rituximab will be given on day 1 with Fludarabine being given on days 2-6. This will allow for appropriate samplings of the effects of Rituximab on lymphocytes before during and at the end of the first 24 hours. In subsequent cycles 2-6, the Rituximab and day 1 Fludarabine can both be given on day 1.