Inclusion Criteria

DISEASE CHARACTERISTICS:

Inclusion criteria:

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

- Disease in complete or partial remission after completion of 4-6 courses of
second-line cytoreductive therapy no less than 90 days and no more than 150 days ago

- Second-line cytoreductive therapy must comprise 1 of the following regimens:

- Fludarabine phosphate alone (F)

- Fludarabine phosphate and cyclophosphamide (FC)

- Fludarabine phosphate, cyclophosphamide, and rituximab (FCR)

- Bendamustine hydrochloride alone (B)

- Bendamustine hydrochloride and rituximab chemotherapy (BR)

- Complete minimal residual disease response defined by the following:

- At least negativity of 4-color-cytometry and/or even PCR-amplifiable clonal CDR
III rearrangement of the IgV_H

- For PCR analysis, blood sample need to be taken at beginning or during
second-line cytoreductive therapy before achievement of a clinical complete
remission

- Disease not refractory to first-line F/FC/FCR/B/BR if received such therapy

Exclusion criteria:

- Presence of bulky lymph nodes (> 5 cm) after second-line F/FC/FCR/B/BR

- Clinically apparent autoimmune cytopenia (i.e., autoimmune hemolytic anemia,
autoimmune thrombocytopenia, or pure red cell aplasia)

- CNS involvement with B-CLL

PATIENT CHARACTERISTICS:

Inclusion criteria:

- ECOG performance status 0-1

- ANC ≥ 1,500/µL

- Platelets ≥ 50,000/µL

- Creatinine ≤ 1.5 times the upper normal limit (ULN)

- Conjugated bilirubin ≤ 2 times ULN

- Thyroid function normal

- Not pregnant or nursing

- Fertile patients must use effective contraception

Exclusion criteria:

- Severe infection during second-line treatment with F/FC/FCR/B/BR, meeting any 1 of
the following criteria:

- Any episode of NCI grade 4 infection

- More than 1 episode of NCI grade 3 infection

- Medical condition requiring long-term use of oral corticosteroids for more than 1
month

- Active bacterial, viral, or fungal infection

- HIV, hepatitis B virus, and/or hepatitis C virus-positive serum status

- Concurrent severe diseases that exclude the administration of protocol therapy,
including any of the following:

- NYHA class III-IV heart insufficiency

- Severe chronic obstructive lung disease with hypoxemia

- Severe ischemic cardiac disease

- Active secondary malignancy other than B-CLL prior to the study

- Known hypersensitivity or anaphylactic reaction against murine proteins or one of the
drug components

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- No more than 2 prior chemotherapies, including F/FC/FCR/B/BR therapy

- No more than 1 pretreatment (before second-line therapy) with chlorambucil or
F/FC/FCR/B/BR

- No chemotherapy or radiotherapy for any neoplastic disease other than B-CLL prior to
the study