Phase I Study of ON 01910.Na in Refractory Leukemia or Myelodysplastic Syndrome (MDS)

This is an open-label, Phase I study to determine the highest amount of the study drug, ON 01910.Na, that can be safety given to patients with high risk myelodysplastic syndromes (MDS) or refractory leukemias. Patients will receive ON 01910.Na (at a starting dose of 650 mg/m2) intravenously by 3-day continuous infusion once every 2 weeks. Successive courses will use longer infusion times and/or higher doses of the drug until toxicity, effectiveness, or ineffectiveness is recognized. In addition, the amount of drug in the blood will be measured, any antitumor activity will be documented, and the biological effect of ON 01910.Na on cell-cycle pathways will be evaluated in peripheral blood mononuclear cells.