• Bone marrow aspiration on day 21 (+/- 2 days) and 28 (+/- 2 days) and every 7-14 days thereafter as indicated until remission is documented, then every 1-3 courses.
  

• During subsequent courses, complete history and physical, CBC, and chemistries will be performed at least once prior to each course of therapy. Correlative studies will be obtained on days 0, and 7 (all +/- 2 days).
  

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.