OBJECTIVES: I. Determine the safety of topotecan in combination with fludarabine, cytarabine, and filgrastim (FLAG) in patients with poor prognosis acute myeloid leukemia, myelodysplastic syndrome, or recurrent or refractory acute lymphocytic leukemia. II. Determine the maximum tolerated dose of topotecan in the FLAG regimen in these patients. III. Assess the complete remission rates in patients treated with this regimen.