5-aza is a chemotherapy drug with activity in leukemia and MDS. Researchers hope that VPA and ATRA will increase the effects of 5-aza. The goal of this clinical research study is to find the highest safe dose of valproic acid (VPA) that can be given in combination with 5-azacytidine (5-aza) and all-trans retinoic acid (ATRA) in the treatment of AML and MDS. The safety and effectiveness of this combination therapy will also be studied.

Additional blood and bone marrow samples will be requested. These samples will be used to evaluate the effect of the treatment on leukemic cells. In addition, any leftover blood and bone marrow samples that are collected at the start of the study and during the regularly scheduled evaluations to be sent for research studies. The research studies will examine changes in the blood and bone marrow cells that might help explain the causes of leukemia and MDS and how the combination of 5-aza, VPA, and ATRA works.

Recent studies have shown synergy between demethylating agents and histone deacetylase inhibitors. In my laboratory, we have developed in vitro models using HL-60 and MOLT4 leukemic cells to study the effects of the combination of decitabine (a 5-azacytidine analogue) and valproic acid. Valproic acid is an antiepileptic agent with histone deacetylase inhibitory capacity. These results indicate that the addition of valproic acid to decitabine has an additive effect on growth inhibition, induction of apoptosis, induction of p57KIP2 and p21CIP1 expression independent of cell cycle arrest. These results were dependent on the dose and duration of treatment but not on the sequence used. Based on this data, we developed a phase I/II study of the combination of decitabine and valproic acid (2003-0314) in patients with leukemia that has shown that valproic acid can be safely administered up to doses of 50 mg/kg orally for 10 days in combination with decitabine, and that this combination has significant activity in patients with relapsed/refractory AML and MDS. All-trans retinoic acid (ATRA) is a biological agent that has been shown to induce cell differentiation in leukemia cell lines and has significant clinical activity in acute promyelocytic leukemia with minimal toxicity. In vitro, the combination of ATRA with either a hypomethylating agent or a histone deacetylase inhibitor has been shown to restore ATRA sensitivity in resistant cells. More recently, a German group has reported that the combination of valproic acid and ATRA has activity in patients with MDS and an excellent toxicity profile. 5-azacytidine is a nucleoside analogue with hypomethylating activity that has been shown in a randomized study to benefit patients with MDS, including an improvement in quality of life. Based on this data, this agent was recently approved by the FDA for its use in patients with MDS, and has become the first line agent for patients with MDS that required therapy.

The objectives of the clinical trial are the following:

• To determine the maximal tolerated dose of valproic acid (VPA) in combination with 5-azacytidine (5-aza) and all-trans retinoic acid.
• To determine the clinical activity of the combination of 5-azacytidine, valproic acid and all-trans retinoic acid in patients with AML and MDS.
• To determine the in vivo molecular and biological effects of this combination. These will include analysis of changes in DNA methylation, histone modifications, and gene expression.

• Myelodysplastic Syndrome
• Acute Myelogenous Leukemia

• Drug: 5-Azacytidine (5-aza)
• Drug: Valproic Acid
• Drug: All-Trans Retinoic Acid (ATRA)

Inclusion Criteria:

• Patients with refractory or relapsed: acute myelogenous leukemia (AML), and myelodysplastic syndrome (MDS) (bone marrow blasts > or = 10%) are eligible.
• Untreated patients older than 60 years of age with AML or MDS (bone marrow blasts > or = 10%) who refuse or are not eligible for front-line chemotherapy, are eligible.
• Performance status of < or = 2 by the ECOG scale.
• Signed informed consent indicating that patients are aware of the investigational nature of this study in keeping with the policies of UTMDACC.
• Age > 2 years. Valproic acid has been associated with a higher rate of severe liver toxicity in children younger than 2 years.
• Patients must have been off chemotherapy for 2 weeks prior to entering this study and recovered from the toxic effects of that therapy, unless there is evidence of rapidly progressive disease. Use of hydroxyurea for patients with rapidly proliferative disease is allowed for the first two weeks on therapy.
• Adequate liver function (bilirubin of < 2mg/dL, SGPT < 3 x ULN) and renal function (creatinine < 2mg/dL).
• Women of childbearing potential must practice contraception. Men and women must continue birth control for the duration of the trial.
• Patients with relapsed /refractory disease with inv16, t(8;21) or t(15;17) are eligible.

Exclusion Criteria:

• Nursing and pregnant females are excluded.
• Patients with active and uncontrolled infections are excluded.
• Patients already receiving valproic acid or receiving other anticonvulsants will be excluded.
• Untreated patients younger than 60 years will not be candidates for this study.
• Patients with untreated disease inv16, t(8;21) or t(15;17) will be excluded.