RATIONALE: Drugs used in chemotherapy use different ways to stop cancer cells from dividing so they stop growing or die. Combining more than one drug may kill more cancer cells. Monoclonal antibodies can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells.

PURPOSE: Phase II trial to study the effectiveness of fludarabine plus high-dose cyclophosphamide and rituximab in treating patients who have previously untreated chronic lymphocytic leukemia.

OBJECTIVES:

• Determine the response rate in patients with chronic lymphocytic leukemia treated with sequential fludarabine, high dose cyclophosphamide, and rituximab.
• Survival up to 5 years
• Utilize flow cytometry and polymerase chain reaction as sensitive measures of minimal residual disease in these patients.

OUTLINE: This is an open label study.

Patients receive fludarabine IV once daily for 5 days. Treatment is repeated every 4 weeks for 3 or 6 courses.

Three weeks later, cyclophosphamide is administered intravenously every 2-3 weeks for 3 courses. Filgrastim (G-CSF) is administered on days 2-10. Beginning 4 weeks after the last dose of cyclophosphamide, patients receive rituximab by intravenous infusion once weekly for 4 weeks.

Patient are followed every 3 months until death.

PROJECTED ACCRUAL: This study will accrue 30 patients within 3 years.

Inclusion criteria:

• Patients must have either intermediate or high-risk chronic lymphocytic leukemia as defined by the three-stage Rai system (see section 2.2 page 2). Patients with Rai intermediate risk disease should meet the criteria for active disease as outlined by the NCI Working Group guidelines (including weight loss, fatigue, fevers, evidence of progressive marrow failure, splenomegaly, progressive lymphadenopathy, or progressive lymphocytosis with a rapid doubling time).
• Patients must be previously untreated (with cytoreductive agents) for their CLL.
• The patient must have an absolute lymphocytosis in the blood of at least 5,000 lymphocytes/μl, or bone marrow lymphocytosis greater than or equal to 30% of all nucleated cells. These lymphocytes must have an appropriate immunophenotype for CLL including expression of CD5 and CD20.
• Karnofsky performance status equal to or greater than 60% (see Appendix B).
• Eligible patients should have a reasonable life-expectancy greater than four weeks.
• Age ≥ 18 years and ≤ 75 years.
• Total bilirubin ≤ 2.0 mg per deciliter. Total creatinine ≤ 2.0 mg/ dl.
• Platelet count ≥ 50,000/ ul.
• Signed informed consent, which indicates the investigational nature of this, is required.
• No patient may be entered onto the study without consultation with the principal investigator.

EXCLUSION CRITERIA:

• Patients with Rai intermediate risk disease who meet the criteria of Montserrat "smouldering leukemia" will not be eligible for treatment on this protocol.
• Patients with significant autoimmune hemolytic anemia or autoimmune thrombocytopenia shall not be eligible for treatment on this protocol as there is some evidence that fludarabine can worsen these conditions.
• Patients with active infections requiring systemic antibiotics.
• Prior cytotoxic treatment of their CLL.
• Pregnant or lactating women. Women and men of childbearing age should use effective contraception.
• Patients with a serious cardiac condition.
• Concomitant chemotherapy or radiotherapy while on protocol.
• Concomitant prednisone therapy will not be permitted as the combination of fludarabine and prednisone is known to increase the risk of opportunistic infections. Patients may receive intravenous immunoglobulin (IVIG) and other supportive care measures as clinically appropriate while on protocol.