Cyclophosphamide, Fludarabine, Alemtuzumab, and Rituximab (CFAR) for Relapsed or Refractory Chronic Lymphocytic Leukemia (CLL)

The goal of this clinical research study is to learn if the combination of fludarabine, cyclophosphamide, alemtuzumab, and rituximab is effective in treating chronic lymphocytic leukemia in patients who have already been treated with chemotherapy. Primary Objectives: Evaluate the therapeutic efficacy, including the complete remission (CR), nodular partial remission (NPR), and partial remission (PR) rates (overall response) of combined cyclophosphamide, fludarabine, alemtuzumab, and rituximab (CFAR) in previously treated patients with Chronic Lymphocytic Leukemia (CLL). Second Objectives: * Assess the toxicity profile of CFAR in previously treated patients with CLL. * Monitor for infection and determine incidence and etiology of infection including cytomegalovirus in patients treated with CFAR. * Evaluate molecular remission by polymerase chain reaction (PCR) for the clonal immunoglobulin heavy chain variable gene in responding patients treated with CFAR. * Assess immune parameters, including pretreatment, during treatment, and post-treatment blood T-cell counts and subset distribution and serum immunoglobulin levels in patients treated with CFAR.