Inclusion Criteria:

1. Understand and voluntarily sign an informed consent form.
2. Age >/= to 16 years at the time of signing the informed consent form.
3. Diagnosis of AML [other than acute promyelocytic leukemia (APL)] with refractory/relapsed disease. Patients with newly diagnosed AML will be eligible if not a candidate for intensive chemotherapy. Patients with high-risk Intermediate-2 or high by IPSS or >/= to 10% blasts) MDS will also be eligible. All non-hematological toxicity of previous cancer therapy should have resolved to </= grade 1 (except alopecia or other toxicities not involving major organs).
4. ECOG performance status of </= to 3 at study entry.
5. Laboratory test results within these ranges (unless due to leukemia): Serum creatinine </= 2 mg/dL Total bilirubin </= 2 mg/dL AST (SGOT) and/or ALT (SGPT) </= 2.5 x ULN or </= 5 x ULN if related to disease
6. Women of childbearing potential (WCBP) must have a negative urine pregnancy test within 7 days and must either commit to continued abstinence from heterosexual intercourse or adopting at least one highly effective method of contraception. These methods include intra-uterine device, tubal ligation, partner's vasectomy, hormonal birth control pills. Men must agree not to father a child and agree to use a condom if his partner is of child bearing potential.

Exclusion Criteria:

1. Pregnant or breastfeeding females.
2. Any condition, including the presence of laboratory abnormalities, which places the patient at unacceptable risk.
3. Use of any other experimental drug or therapy for leukemia within 7 days unless there is clear evidence of rapid disease progression.
4. Use of hydrea to control proliferative disease will be allowed prior to starting therapy on study and for up to 7 days each during cycle 1-3 (Maximum daily dose of 7gm).