Pentostatin, Cyclophosphamide, Rituximab, and Mitoxantrone in Treating Patients With Chronic Lymphocytic Leukemia or Other Low-Grade B-Cell Cancer

RATIONALE: Pentostatin may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth. Drugs used in chemotherapy, such as cyclophosphamide and mitoxantrone, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. 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. Giving pentostatin together with combination chemotherapy and rituximab may kill more cancer cells. PURPOSE: This phase I/II trial is studying the side effects and best dose of mitoxantrone when given together with pentostatin, cyclophosphamide, and rituximab and to see how well it works in treating patients with chronic lymphocytic leukemia or other low-grade B-cell cancer.

OUTLINE: This is a phase I, dose-escalation study of mitoxantrone hydrochloride followed by a phase II study. * Phase I: Patients receive pentostatin IV, cyclophosphamide IV, and mitoxantrone hydrochloride IV on day 1. Patients also receive rituximab IV on day 1 beginning in course 2. Treatment repeats every 4 weeks for up to 6 courses in the absence of disease progression or unacceptable toxicity. * Phase II: Patients receive pentostatin, cyclophosphamide, rituximab, and mitoxantrone hydrochloride (at the maximum tolerated dose determined in phase I) as in phase I. All patients receive either pegfilgrastim subcutaneously (SC) on days 1-4 following each course or filgrastim or sargramostim SC beginning 2 days after each course until blood counts recover. Patients undergo blood collection and bone marrow biopsy periodically for assessment of therapy response by biomarker and laboratory studies. Samples are analyzed for molecular genetics for IgH arrangement by PCR and for response by immunoelectrophoresis. Some samples are analyzed for response by flow cytometry or fluorescence in situ hybridization (FISH). After completion of study treatment, patients are followed every 3 months for 1 year. PROJECTED ACCRUAL: A total of 63 patients (18 patients for phase I and 45 patients for phase II) will be accrued for this study.