Rituximab, Cyclophosphamide, and Pegfilgrastim in Treating Patients With Leukemia or Non-Hodgkin's Lymphoma

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.