If a patient has a DLT (see definition above) beyond the completion of the first 21-day cycle, administration of oral ON 01910.Na, treatment will be discontinued or reduced (at the discretion of the Principal Investigator) to the lower dose level, or by 25% if the patient was treated at the 70mg dose level. Patients should return to within 20% of their baseline, pre-cycle ANC, platelet or hemoglobin levels prior to treatment with a subsequent cycle. Treatment can be delayed for up to 21 days (1 cycle length) until counts return to their pre-treatment baseline. If counts are still not adequate for treatment, the patient will be re-evaluated 2 weeks later. If any non-hematological toxicity of Grade 2 or 3 is present on the day of ON 01910.Na administration, the drug administration will be withheld until resolution to ≤ grade 1 toxicity is present.