Inclusion Criteria:

- Documented relapsed or refractory B-cell NHL; CD-20 positive tumor. Indolent NHL:
follicular B-cell lymphoma, diffuse small lymphocytic lymphoma, lymphoplasmacytic
lymphoma, marginal zone lymphoma, transformed aggressive lymphomas, mantle cell
lymphoma and chronic lymphocytic leukemia

- Maximum of 6 prior chemotherapy regimens. Prior rituximab is allowed.

- Bidimensionally measurable disease

- ECOG performance status 0-2

- Absolute neutrophil count >/= 1000 and platelet count >/= 50,000

- Serum creatinine
- Adequate hepatic function

- Estimated life expectancy of at least 3 months

- All study participants must be registered into the mandatory RevAssist program and be
willing and able to comply with the requirements of RevAssist

- Able to take aspirin 81 mg daily as prophylactic anticoagulation

Exclusion Criteria:

- Chemotherapy or immunotherapy within 3 weeks prior to entering study or failure to
recover from adverse events due to any agents administered previously

- Use of investigational agents within 28 days of study

- Hematopoietic growth factors within 14 days of study

- History of prior high dose chemotherapy with allogeneic stem cell support

- History of prior radioimmunotherapy
- Concurrent treatment with therapeutic doses of systemic steroids

- Pregnant or lactating female subjects

- Concurrent, active malignancy other than lymphoma or CLL

- Primary CNS lymphoma

- Patients with a prior diagnosis of lymphoma active in the CNS are eligible only if
CNS has been treated, and they are neurologically stable with no progressive symptoms
off steroids and anti-convulsants

- Serious infection, medical condition, or psychiatric condition that, in the opinion
of the investigator, might interfere with the achievement of study objectives

- Hypersensitivity to murine proteins or to any component of rituximab

- Known positive for HIV or infectious hepatitis type C; hepatitis type B that is
active and uncontrolled

- Hypersensitivity to mannitol

- Evidence of laboratory tumor lysis syndrome by Cairo-Bishop criteria

- Subject with recent thromboembolic event (deep vein thrombosis or pulmonary embolism)
unless clinically stable and event occurred more than 2 weeks prior to enrollment.