A Phase I-II Study of Pentostatin With Cyclophosphamide for Previously Treated Patients With Intermediate and High-Risk Chronic Lymphocytic Leukemia

OBJECTIVES:

• Determine the dose of cyclophosphamide, with filgrastim (G-CSF) support, that can be safely administered with pentostatin and rituximab in patients with previously treated intermediate- or high-risk chronic lymphocytic leukemia or other low-grade B-cell malignancies. (Phase I closed to accrual effective 11/27/2001.)
• Characterize the toxicity of this regimen in these patients.
• Determine the incidence of response in these patients treated with this regimen.

OUTLINE: This is a multicenter, dose-escalation study of cyclophosphamide (CTX).

• Phase I: Patients receive CTX IV followed by pentostatin IV on day 1 of course 1. Patients also receive filgrastim (G-CSF) subcutaneously once daily beginning on day 3 and continuing until blood counts recover. During the second and subsequent courses, patients receive CTX IV, pentostatin IV, and rituximab IV on day 1. Patients also receive G-CSF as in course 1. Treatment repeats every 3 weeks for 3 courses in the absence of disease progression or unacceptable toxicity. Patients with at least a partial response after the third course receive an additional 3 courses.

Cohorts of 3-6 patients receive escalating doses of CTX until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which at least 2 of 6 patients experience dose-limiting toxicity.