INDUCTION CHEMOTHERAPY (G-CLAM): Patients receive G-CLAM chemotherapy comprising filgrastim subcutaneously (SC) daily on days 0-5, mitoxantrone hydrochloride intravenously (IV) over 60 minutes on days 1-3, cladribine IV over 2 hours daily on days 1-5, and cytarabine IV over 2 hours daily on days 1-5. Patients achieving complete remission with incomplete peripheral blood count recovery (CRi), partial remission, or persistent disease may receive a second course of induction chemotherapy. Patients achieving complete remission (CR) or CR with incomplete platelet count recovery (CRp) may continue on to Consolidation Chemotherapy.