(a) relapsed or refractory leukemia after receiving at least one prior conventional induction therapy. Those in early first relapse must not have a matched donor and/or they must not be a candidate for allogeneic stem cell transplantation (usually this would mean the patient is too ill, obese, has a co-morbid condition or is over the age of 55 years) or (b) poor-risk AML as defined below: (i) Treatment related AML, except if it is associated with favorable cytogenetics (e.g., inversion 16, t(16;16), t(8;21), t(15;17), and not a candidate for stem cell transplantation, or (ii) AML with an antecedent hematologic disease (e.g., MDS, myelofibrosis, polycythemia vera, etc.), and not a candidate for stem cell transplantation.