Efficacy and Safety of 5-day Dosing of ON 01910.Na in Intermediate-1,-2, or High Risk Myelodysplastic Syndrome (MDS)

This is a single center, open label, phase 1/2 study in which two to thirty three patients with Intermediate-1, Intermediate-2, or High risk MDS will receive ON 01910.Na as a intravenous continuous infusion (IVCI) over 24 hours for 5 consecutive days every 2 weeks. In the phase 1 component of this trial the maximum tolerated dose of ON1910.Na in patients with Intermediate-1, Intermediate-2 or High Risk myelodysplastic syndromes will be determined. A standard "3+3" dose escalation scheme will be followed with up to six patients treated at the 800 mg/m2/day dose level. Patients will be observed for 2 cycles before dose escalation occurs. If none of the initial three patients in the 800 mg/m2/day cohort experience dose-limiting toxicity (DLT), during the first two cycles, then a new cohort of three patients will be treated at the 1500 mg/m2/day dose level. If none of the initial three patients in the 1500 mg/m2/day cohort experience DLT during the first two cycles, three additional patients will be treated at the 1500 mg/m2/day level. If no more than one of the six patients at the 1500 mg/m2/day dose level experiences a DLT, then that dose level will be confirmed as the MTD and no further dose escalation will occur. If one of the three patients in the 800 mg/m2/day cohort experiences DLT during the first two cycles, then up to three additional patients will be treated at the same dose level. Escalation to 1500 mg/m2/day will proceed if only one of the six patients experiences DLT at the 800 mg/m2/day dose level. If two or more patients in the 800 mg/m2/day cohort experience DLT during the first two cycles, then the maximum tolerated dose (MTD) will have been exceeded, no further dose escalation will occur, and a full safety review will determine if further enrollment of patients will proceed. If the 800 mg/m2/day dose level is under consideration as the MTD (i.e. if ≥ 2 patients experience DLT at the 1500 mg/m2/day dose level), and only three patients were treated before escalation to 1500 mg/m2/day, then three additional patients will be accrued. If no more than one of the six patients at the 800 mg/m2/day dose level experiences a DLT, then that dose level will be confirmed as the MTD. Once the phase 1 portion of the study is completed, accrual to the phase 2 portion will begin. Patients treated at the MTD during the phase 1 portion will be included in the phase 2 component and will be evaluated for response and secondary end points. The total study duration is 29 weeks, which includes a 2-week screening phase, a 23-week dosing phase, and a 4-week follow-up phase that begins after the last dose of ON 01910.Na. Patients will be assessed for response and will undergo follow up. Patients who drop out for any reason will not be replaced. Patients who achieve a complete or partial response or stabilization of their disease by week 25 are eligible to receive an additional 24 weeks of ON 01910.Na at the same dose they received during the first 24 weeks of treatment(800 or 1500 mg/m2/day IVCI for 5 days Q2W).