RATIONALE: Monoclonal antibodies, such as rituximab, can block cancer growth in different ways. Some block the ability of cancer cells to grow and spread. Others find cancer cells and help kill them or carry cancer-killing substances to them. Drugs used in chemotherapy, such as cyclophosphamide, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Colony-stimulating factors, such as pegfilgrastim, may increase the number of immune cells found in bone marrow or peripheral blood and may help the immune system recover from the side effects of chemotherapy. Giving rituximab and cyclophosphamide together with pegfilgrastim may be effective in treating leukemia or non-Hodgkin's lymphoma.

PURPOSE: This phase II trial is studying how well giving rituximab and cyclophosphamide together with pegfilgrastim works in treating patients with B-cell leukemia, low-grade non-Hodgkin's lymphoma, or mantle cell lymphoma.

OBJECTIVES:

• Determine the safety of high-dose cyclophosphamide, rituximab, and pegfilgrastim in patients with B-cell leukemia or low-grade or mantle cell lymphoma.
• Determine the molecular response rate in patients treated with this regimen.

OUTLINE: This is an open-label study.

Patients receive rituximab IV over 30-60 minutes on days 1, 4, 8,11, 45, and 52, cyclophosphamide IV over 1 hour on days 15-18, and pegfilgrastim subcutaneously on day 19 or 20 in the absence of unacceptable toxicity.

After completion of study treatment, patients are followed periodically.

PROJECTED ACCRUAL: A total of 32 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• One of the following B-cell leukemias or lymphomas, as defined by World Health Organization criteria:

  • Chronic lymphocytic leukemia/small lymphocytic lymphoma
  • B-cell prolymphocytic leukemia
  • Lymphoplasmacytic leukemia
  • Marginal zone lymphoma (splenic, extranodal, or nodal)
  • Follicular lymphoma (grade 1 or 2)
  • Mantle cell lymphoma

• No more than minimal (approximately 10%) morphologically identifiable cancer cells on bone marrow biopsy

  • When cancer cells are morphologically difficult to distinguish from normal cells, flow cytometry must show no more than 10% identifiable cancer cells

• Must have received ≤ 12 months of prior cytotoxic therapy, achieving at least a partial response NOTE: A new classification scheme for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol uses the former terminology.

PATIENT CHARACTERISTICS:

• ECOG performance status 0-1
• WBC ≥ 3,000/mm^3
• Hemoglobin ≥ 10.0 g/dL
• Platelet count ≥ 75,000/mm^3
• Serum creatinine ≤ 2.0 mg/dL
• Total bilirubin ≤ 2 mg/dL unless secondary to tumor
• AST or ALT < 2 times upper limit of normal
• Normal (≥ 45%) left ventricular cardiac ejection fraction (determined by echocardiogram or MUGA scan)
• DLCO > 50% predicted
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No known sensitivity to E. coli-derived products (e.g. filgrastim [G-CSF], insulin, asparaginase, growth hormone, or recombinant interferon alfa-2b) or any treatment study drugs
• No active infections requiring oral or intravenous antibiotics
• No other second malignancy other than basal cell or squamous cell carcinoma of the skin or in situ carcinoma of the cervix unless the malignancy was localized and treated or resected with > 90% probability of cure

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• Prior anti-CD20 therapy allowed provided patient achieved a partial or complete response
• No concurrent steroids during rituximab administration

Up to 1 year

Adverse events were assessed at least weekly through Day 60, then at Day 180 and one year.