INCLUSION CRITERIA:

• Men or women ≥18 years of age
• Histopathologically confirmed diagnosis of B-CLL expressing surface CD20 of any detectable intensity
• Rai Stage III or IV. Rai Stages I and II with massive or progressive lymphadenopathy or hepatosplenomegaly.
• Primary resistance to a fludarabine regimen (no PR or CR) or progressive disease within 1 year of a prior response
• ECOG performance status 0, 1, or 2
• Written informed consent

EXCLUSION CRITERIA:

• Therapy for CLL within 4 weeks of Study Day 1 (including chemotherapy, radiation, immunotherapy, cytokine or biologic [with the exception of hematopoietic growth factors]). Patients must have recovered from the adverse effects of prior therapy.
• Known primary or secondary malignancy of the central nervous system
• Any malignancy within the 5 years immediately prior to the first dose of study medication with the exception of basal cell or non-metastatic squamous cell carcinoma of the skin, and carcinoma in-situ of the cervix
• Serum creatinine >2.0mg/dL (>176 micromol/L)
• AST or ALT ≥3 x the upper limit of normal (ULN)
• Total bilirubin ≥1.5 x ULN (unless secondary to Gilbert’s)
• Positive serology for hepatitis B (HBsAg) or hepatitis C (anti-HCV antibody)
• Known positivity for HIV
• Prior organ allograft
• Concurrent comorbid medical conditions that, in the opinion of the investigator, preclude the safe delivery of the experimental treatment
• Pregnant or nursing women