Study of Talabostat and Rituximab in Advanced Chronic Lymphocytic Leukemia (CLL)

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