OBJECTIVES: I. Determine the maximum tolerated dose of topotecan when combined with etoposide in patients with relapsed or refractory acute myelogenous leukemia, acute lymphoblastic leukemia, or blastic phase chronic myelogenous leukemia. II. Determine the toxicity of this regimen in these patients. III. Measure serum levels of topotecan at steady state and correlate them with any change in topoisomerase II content in leukemic blasts. IV. Assess whether it is feasible to correlate any upregulation of topoisomerase II expression with tumor response to etoposide in subsequent Phase II studies. V. Assess whether levels of pretreatment expression of topoisomerases I and II in leukemic cells are predictive of clinical response. VI. Assess whether it is feasible to develop a pharmacodynamic assay based on posttreatment apoptotic changes in leukemic blasts and whether this could be correlated with tumor response in subsequent phase II trials. VII. Determine the response in patients treated with this regimen.