Patients receive oral imatinib mesylate once daily on days 1-15 and cladribine IV over 2 hours and cytarabine IV over 4 hours on days 3-7. Patients also receive filgrastim (G-CSF) subcutaneously on days 2-7. Treatment repeats every 15 days for 2 courses in the absence of disease progression or unacceptable toxicity.