This study will explore the efficacy and safety of a regimen of ON 01910.Na as a 48-hour continuous intravenous infusion once a week for 3 weeks of a 4-week cycle in MDS patients with Trisomy 8 or classified as Intermediate-1, -2 or High Risk who are not responding to current therapeutic options. The rationale for this trial is based upon data from laboratory studies with ON 01910.Na and upon activity that has been observed in other clinical trials with ON 01910.Na in patients with MDS.

This is a phase 2, study in which 14 MDS patients with Trisomy 8 or classified as Intermediate-1, -2 and High risk who meet all other inclusion/exclusion criteria will receive ON 01910.Na 800 mg/m^2/24h as an continuous intravenous infusion (CIV) over 48 hours once a week for 3 weeks of a 4-week cycle. As of Amendment 3 to the Protocol, the regimen is changed to 1800 mg/24h for 72 hours every other week for the first four 2-week cycles and every 4 weeks afterwards. The total study duration is 31 weeks, which includes a 2-week screening phase, a 27-week dosing phase, and a 4-week follow-up phase that begins after the last dose of ON 01910.Na. Beginning at week 4, and every 2 weeks thereafter, patients will be assessed for response. Patients who drop out for any reason will not be replaced. Patients who achieve by week 29 a complete or partial response or stabilization of their disease are eligible to receive an additional 24 weeks of ON 01910.Na 1800 mg/24 h over 72 hours per week of a 4-week cycle.

Inclusion Criteria:

• Diagnosis of MDS confirmed within 2 weeks prior to study entry according to the World Health Organization (WHO) Criteria or the French-American-British (FAB) Classification.
• Trisomy 8 cytogenetics (simple or combined to other karyotypes) or patient classified as Intermediate-1 with bone marrow blasts equal to or greater than 5%, Intermediate-2 or High Risk MDS according to the IPSS score, or Patients with peripheral blood blasts equal to or greater than 5%.
• At least one cytopenia (Absolute Neutrophil Count < 1800/µl or Platelet Count <100,000/µl or Hemoglobin < 10 g/dL).
• Failure of, or insufficient response to Azacytidine or Decitabine administered for 4 to 6 cycles in patients classified as Intermediate-2 or High risk or to Erythrocyte stimulating agents (failure or insufficient response defined as transfusion dependence or Hemoglobin remaining below 10 g/dl) in Low or Intermediate-1 Risk Trisomy 8 patients.
• Failed to respond to, relapsed following, or opted not to participate in bone marrow transplantation.
• Off all other treatments for MDS (including filgrastim (G-CSF) and erythropoietin) for at least four weeks. As an exception, filgrastim (G-CSF) can be used before, during and after the protocol treatment for patients with documented febrile neutropenia (< 500/µl).
• ECOG Performance Status 0, 1 or 2.
• Willing to adhere to the prohibitions and restrictions specified in this protocol.
• Patient (or his/her legally authorized representative) must have signed an informed consent document indicating that he/she understands the purpose of and procedures required for the study and is willing to participate in the study.

Exclusion Criteria:

• Anemia due to factors other than MDS (including hemolysis or gastrointestinal bleeding).
• Hypoplastic MDS (cellularity <10%).
• Any active malignancy within the past year except basal cell or squamous cell skin cancer or carcinoma in situ of the cervix or breast.
• History of HIV-1 seropositivity.
• Uncontrolled intercurrent illness including, but not limited to symptomatic congestive heart failure, unstable angina pectoris or cardiac arrhythmia.
• Active infection not adequately responding to appropriate therapy.
• Total bilirubin > 1.5 mg/dL not related to hemolysis or Gilbert's disease, ALT or AST > 2 X ULN.
• Serum creatinine > 2.0 mg/dL or calculated creatinine clearance < 60 ml/min/1.73 m^2.
• Ascites requiring active medical management including paracentesis, or hyponatremia (defined as serum sodium value of <134 Meq/L).
• Women patients who are pregnant or lactating; Male patients with female sexual partners who are unwilling to follow the strict contraception requirements described in this protocol; Patients who do not agree to use adequate contraceptive [including prescription oral contraceptives (birth control pills), contraceptive injections, intrauterine device (IUD), double-barrier method (spermicidal jelly or foam with condoms or diaphragm), contraceptive patch, or surgical sterilization] before entry and throughout the study; Female patients with reproductive potential who do not have a negative serum beta-HCG pregnancy test at screening.
• Major surgery without full recovery or major surgery within 3 weeks of ON 01910.Na treatment start.
• Uncontrolled hypertension (defined as a systolic pressure equal to or greater than 160 mmHg and/or a diastolic pressure equal to or greater than 110 mmHg).
• New onset seizures (within 3 months prior to the first dose of ON 01910.Na) or poorly controlled seizures
• Any concurrent investigational agent or chemotherapy, radiotherapy or immunotherapy.
• Treatment with standard MDS therapies or investigational therapy within 4 weeks of starting ON 01910.Na.
• Psychiatric illness/social situations that would limit the patient's ability to tolerate and/or comply with study requirements.