OUTLINE: Patients receive mitomycin C by IV bolus on day 1 of treatment. Patients receive mitoxantrone beginning on day 4. One patient each is entered at the first and second dose levels. Dose escalation of mitoxantrone continues in the absence of toxicity. If the patient experiences toxicity at level 1 or 2, then 2 additional patients are entered at that tier. Three patients are entered at all subsequent tiers. At these tiers, if no toxicity is observed, escalation continues. If 1 of the 3 patients experiences toxicity, an additional 3 patients are enrolled at the same dose. If none of these additional patients experiences toxicity, escalation continues; however, if 1 patient has toxicity, the trial is stopped. If 2 or more have toxicities, the dose is de-escalated. If 2 or more of the original 3 patients have toxicities, the dose is de-escalated. On day 15, patients are treated with sargramostim (GM-CSF) intravenously over 4 hours if the bone marrow is free of residual leukemia; GM-CSF treatment continues until the ANC is greater than 1,500/mm3 for 3 consecutive days.