OBJECTIVES: I. Determine the toxicity, remission rate, event-free survival, and overall survival following induction with cytarabine/mitoxantrone (ARA-C/DHAD), intensification with ARA-C and etoposide (VP-16), and consolidation with cladribine (2-CdA) and VP-16 in patients with acute myeloid leukemia (AML) that is secondary, in first relapse, or has failed initial remission induction therapy. II. Compare the remission induction rate and event-free survival on this trial with prior second-line studies (i.e., protocols CCG-243, CCG-201, and CCG-261P). III. Compare survival of patients on this trial with the survival of patients relapsing or failing to achieve an initial complete remission (CR) on previous front-line AML trials (i.e., protocols CCG-251, CCG-213, CCG-2861, and CCG-2891). IV. Determine the frequency and prognostic significance of mdr1 gene expression and p53, topoisomerase II, and deoxycytidine kinase gene mutations in these patients. V. Determine the disease-free and overall survival of patients achieving a CR on this study in relation to the post-intensification therapy received (i.e., bone marrow transplantation, chemotherapy, or no further therapy). VI. Determine the frequency and degree of abnormal cardiac function on echocardiogram or MUGA at 1 and 5 years in patients treated with mitoxantrone following anthracycline therapy during initial treatment. VII. Provide a control arm evaluating the safety of using phase I or II agents in an "upfront window" approach planned for future CCG studies. VIII. Determine the toxicity, remission rate, event-free survival, and overall survival in patients who fail to achieve a CR with ARA-C/DHAD induction and are then treated with 2-CdA/VP-16. IX. Determine the biologic characteristics, toxicity, remission rate, event-free survival, and overall survival following this treatment regimen in patients who develop AML as a second malignancy.