• PHASE I PORTION ONLY: Patients of any age who have received no more than one prior attempt at induction chemotherapy (and may have received treatment consolidation), must have recovered from acute toxicities of therapy and be >= 4 weeks from last dose of cytotoxic treatment; patients who have received prior autologous or allogeneic stem cell transplantation are not eligible; patients may have received 1 or 2 cycles of cytarabine-based therapy as attempted induction.