Alemtuzumab in Treating Patients With B-Cell Chronic Lymphocytic Leukemia

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