Inclusion Criteria

DISEASE CHARACTERISTICS:

- Diagnosis of B-cell chronic lymphocytic leukemia (B-CLL) requiring treatment

- Previously untreated Binet stage C or Binet B requiring treatment according to
NCI criteria

- Relapsed or refractory disease after treatment with ≥ 1 but no more than 3 prior
regimens

- Prior bendamustine allowed provided patient achieved at least a partial
response that lasted at least 6 months AND completed treatment more than 6
months ago

- No progression to more aggressive B-cell cancers, such as Richter's syndrome

- No known CNS involvement with B-CLL

PATIENT CHARACTERISTICS:

- WHO 0-2

- Life expectancy > 12 weeks

- Absolute neutrophil count ≥ 1,500/mm^3, unless due to bone marrow involvement of CLL

- Platelet count ≥ 75,000/mm^3, unless due to bone marrow involvement of CLL

- Creatinine ≤ 1.5 times upper limit of normal (ULN) OR

- Creatinine clearance > 30 mL/min

- Bilirubin, AST, and ALT ≤ 2 times ULN, unless directly attributable to the patient's
tumor

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception during and for a minimum of 6
months after study therapy

- No history of anaphylaxis after exposure to monoclonal antibodies

- No known HIV

- No hepatitis B or C positivity

- No major organ malfunction (liver, kidney) that could interfere with the patient's
ability to participate in the study

- No active infection or history of severe infection (grade 4) within 3 months prior to
study registration

- No medical condition requiring prolonged use of oral corticosteroids (> 1 month)

- No severe diabetes

- No active secondary malignancy

- No pulmonary disease (chronic obstructive pulmonary disease [COPD] with hypoxemia)

- No tuberculosis

- No New York Heart Association class III or IV heart disease

- No severe hypertension

- No other severe concurrent diseases

- No mental disorders

- No circumstance at the time of study entry that would preclude completion of the
study or the required follow-up

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- More than 3 weeks since prior anticancer therapy, major surgery, or irradiation

- Recovered from the acute side effects incurred as a result of previous therapy

- No use of investigational agents within 30 days prior to study

- No participation in another clinical trial