ARM II: Patients receive PSC 833 IV continuously on days 1-3 and cytarabine, daunorubicin, and etoposide as in arm I. Patients with 20% or greater bone marrow cellularity and greater than 5% leukemia blasts at the end of the first course receive a second course of PSC 833 IV continuously on days 1 and 2 and cytarabine, daunorubicin, and etoposide as in arm I.