I. Estimate the maximum tolerated dose (MTD) of dose-intensified mitoxantrone hydrochloride (mitoxantrone) as part of the filgrastim (G-CSF), cladribine, cytarabine, mitoxantrone hydrochloride (G-CLAM) regimen separately for adults with newly diagnosed acute myeloid leukemia (AML) and those with relapsed/refractory AML receiving first or greater salvage therapy.