Methods of treating, preventing or managing antecedent hematologic disorders, such as myelodysplastic syndrome, including chronic myelomonocytic leukemia are disclosed. The methods encompass the administration of SNS-595. Also provided are methods of treatment using this compound with chemotherapy, radiation therapy, hormonal therapy, biological therapy or immunotherapy. In certain embodiments, the method of treatment comprise administering SNS-595 in combination with cytarabine. Pharmaceutical compositions and single unit dosage forms suitable for use in the methods are also disclosed.