Phase I/II Study of 5-Azacytidine With Ara-C in Patients With Relapsed/Refractory Acute Myelogenous Leukemia (AML) or High Risk Myelodysplastic Syndrome (MDS)

Inclusion Criteria:

1. Patients must have histologically confirmed Acute Myeloid Leukemia (AML) or high risk and previously treated Myelodysplastic Syndrome (MDS).
2. Patients with (1) refractory disease or (2) first relapse within 6 months of therapy or (3) 2nd or more of relapse of Acute Myelogenous Leukemia (AML) or high risk Myelodysplastic Syndrome MDS will be considered for the study.
3. Patients must have been off chemotherapy for 4 weeks prior to entering this study and recovered from the toxic effects of that therapy, unless there is evidence of rapidly progressive disease.
4. Age \>=18 years. Deoxyribonucleic acid (DNA) methylation plays a significant role in development, and the effects of azacitidine in children are not well described.
5. Patients must have normal organ as defined: Total bilirubin \<2 mg, aspartate aminotransferase (AST)/alanine aminotransferase (ALT) \<2.5 x institutional upper limit of normal, Creatinine \<2 mg
6. Ability to understand and the willingness to sign a written informed consent document.
7. Women of child bearing potential must have a negative serum pregnancy test prior to azacitidine treatment.
8. Women of child bearing potential should be advised to avoid becoming pregnant and men should be advised to not father a child while receiving treatment with azacytidine.
9. Eastern Cooperative Oncology Group (ECOG) performance status 0-2.

Exclusion Criteria:

1. Patients who have had chemotherapy or radiotherapy within 4 weeks (6 weeks for nitrosoureas or mitomycin C) prior to entering the study or those who have not recovered from adverse events due to agents administered more than 4 weeks earlier, unless there is evidence of rapidly progressive disease. Patients may have received hydroxyurea prior to entering the study.
2. Patients may not be receiving any other investigational agents for their leukemias.
3. Patients with active brain or meningeal disease should be excluded.
4. Known or suspected hypersensitivity to azacitidine or mannitol
5. Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, or psychiatric illness/social situations that would limit compliance with study requirements.
6. Pregnant women are excluded from this study because azacitidine is a Deoxyribonucleic acid (DNA) methyltransferase inhibitor which has teratogenic or abortifacient effects. Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with azacitidine, breastfeeding should be discontinued if the mother is treated with azacitidine.