Pentostatin, Alemtuzumab, and Rituximab in Treating Patients With Relapsed or Refractory Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma

DISEASE CHARACTERISTICS:

* Histologically or cytologically confirmed chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) meeting the following criteria:

  * Minimum threshold peripheral blood lymphocyte count of 5 x 10\^9/L (CLL variant) OR adenopathy \> 1 cm or palpable splenomegaly (SLL variant)
  * Immunophenotypic demonstrations of a population of B lymphocytes (as defined by CD19+) that are monoclonal (by light chain exclusion) AND have ≥ 3 of the following characteristics:

    * CD5+
    * CD23+
    * Dim surface light chain expression
    * Dim surface CD20 expression
    * FISH analysis is negative for IGH/CCND1 and/or immunostaining is negative for cyclin D1 expression
* Must have progressive disease as indicated by any of the following characteristics (based on standard criteria for treatment):

  * Symptomatic CLL characterized by any of the following:

    * Weight loss \> 10% within the past 6 months
    * Extreme fatigue
    * Fevers \> 38.5° C (not due to infection)
    * Drenching night sweats without evidence of infection
  * Evidence of progressive bone marrow failure with hemoglobin \< 11 g/dL or platelet count \< 100 x 10\^9/L
  * Massive and progressive splenomegaly (\> 6 cm below left costal margin)
  * Massive (\> 10 cm) or rapidly progressive lymphadenopathy

PATIENT CHARACTERISTICS:

* ECOG performance status 0-3
* Creatinine ≤ 2 times upper limit of normal (ULN)
* Total bilirubin ≤ 3.0 times ULN OR direct bilirubin ≤ 1.5 times ULN
* AST ≤ 3.0 times ULN (unless due to hemolysis or CLL)
* Willing to provide mandatory blood samples for research studies
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception during and for up to 12 months after completion of study treatment
* No other active primary malignancy that requires treatment or limits survival to ≤ 2 years
* No active autoimmune hemolytic anemia, immune thrombocytopenia, or pure red blood cell aplasia
* No New York Heart Association class III or IV heart disease
* No myocardial infarction within the past month
* No uncontrolled infection
* No HIV infection or AIDS
* No active hepatitis B infection (i.e., HBsAg or HBeAg positivity) or hepatitis C infection by serology
* No other comorbid condition

PRIOR CONCURRENT THERAPY:

* No more than 3 prior treatment regimens for CLL that included purine analogue drugs (e.g., fludarabine, pentostatin, or cladribine) OR previously untreated CLL in patients with high-risk disease due to 17p13 deletion on FISH analysis
* More than 4 weeks since prior major surgery
* More than 2 months since prior alemtuzumab
* Prior corticosteroids allowed
* No concurrent continuous systemic corticosteroids