Study of XL999 in Patients With Acute Myeloid Leukemia (AML)

Inclusion Criteria: * Diagnosis of acute myeloid leukemia (except AML FAB-M3 or acute promyelocytic leukemia \[APL\]) based on the World Health Organization (WHO) classification of ≥ 20% blasts in the bone marrow or peripheral blood at initial diagnosis (prior to start of standard chemotherapy) * ECOG performance status of 0 or 1 * Subjects with newly-diagnosed AML or subjects with relapsed AML after at least 2 chemotherapy regimens. * Adequate liver and renal function * Signed informed consent Exclusion Criteria: * Anticancer therapy including chemotherapeutic, biologic, or investigative agents within 30 days of XL999 treatment * Hematopoietic stem cell transplantation within the previous 6 weeks * Immunosuppressive therapy (eg, cyclosporine, steroids, tacrolimus) for graft-versus-host disease (GvHD) within 30 days prior to the start of XL999 * The subject has not recovered to grade ≤ 1 or to within 10% of baseline from adverse events due to investigational or chemotherapeutic drugs or stem cell transplantation which were administered \> 4 weeks prior to study enrollment * Uncontrolled and/or concomitant illness * Pregnant or breastfeeding females * Known HIV