Inclusion Criteria:

1. Males and females age ≥ 18 years;

2. Histopathologically documented primary or secondary AML, as defined by WHO criteria
(Jaffe et al, 2001), confirmed by pathology review at treating institution, meeting
at least one of the following:

1. Refractory to at least 1 cycle of induction chemotherapy, or

2. Relapsed after at least 1 cycle of induction chemotherapy, or

3. Patient is not, according to the clinical judgment of the Principal
Investigator, a candidate for induction chemotherapy due to age, comorbidity, or
other factors;

3. Patients for whom no standard therapies are anticipated to result in a durable
remission, or who have failed potentially curative therapy, or who refuse standard
therapy or patients for whom there is no known therapy of documented treatment
benefit;

4. Eastern Cooperative Oncology Group (ECOG) performance status of 0-3;

5. In the absence of rapidly progressing disease, the interval from prior treatment to
time of AC220 administration should be at least 2 weeks for cytotoxic agents (other
than hydroxyurea, per Section 8.8), or at least 5 half-lives for noncytotoxic agents;

6. Persistent chronic clinically significant toxicities from prior chemotherapy or
surgery must be less than Grade 2;

7. Serum creatinine ≤ 2.0 mg/dL;

8. Total serum bilirubin ≤ 1.5 × ULN unless considered due to Gilbert's syndrome or
leukemic organ involvement;

9. Serum AST or ALT ≤ 3.0 × ULN unless considered due to leukemic organ involvement;

10. Females of childbearing potential must have a negative pregnancy test (urine β-hCG);

11. Females of childbearing potential and sexually mature males must agree to use a
medically accepted method of contraception throughout the study;

12. Written informed consent must be provided.

Exclusion Criteria:

1. Histologic diagnosis of acute promyelocytic leukemia;

2. Clinically active central nervous system leukemia;

3. Persistent clinically significant toxicity from prior chemotherapy that is Grade 2 or
higher by the National Cancer Institute Common Terminology Criteria for Adverse
Events (CTCAE v3);

4. Bone marrow transplant within 2 months prior to study;

5. Active, uncontrolled infection;

6. Major surgery within 4 weeks prior to study;

7. Radiation therapy within 4 weeks prior to, or concurrent with, study;

8. Human immunodeficiency virus positivity;

9. Active hepatitis B or C or other active liver disease;

10. Women who are pregnant, lactating, or unwilling to use contraception if of
childbearing potential;

11. Medical condition, serious intercurrent illness, or other extenuating circumstance
that, in the judgment of the Principal Investigator, could jeopardize patient safety
or interfere with the objectives of the study.