ARM I: Patients receive alvocidib intravenously (IV) over 1 hour on days 1-3, cytarabine IV over 72 hours on days 6-8, and mitoxantrone hydrochloride IV over 1-2 hours on day 9. Patients who achieve complete or partial response to the first course (completion of all doses) may receive a second course of treatment or high-dose cytarabine after 21-63 days following blood count recovery, and/or undergo allogeneic bone marrow transplant.