Part II will proceed if measurable drug levels have been measured in Part I and in the absence of DLT at the 70 mg single dose level in Part I. The maximum tolerated dose of oral ON1910.Na administered in a fasting state (defined as no less than 30 minutes before next meal) twice a day for 14 consecutive days will be determined in patients in patients with Low, Intermediate-1, Intermediate-2 or High Risk MDS following an adaptive design.