Oral Rigosertib in Low Risk MDS Patients Refractory to ESAs

The study will enroll low risk MDS patients who need red blood cell transfusions and who are refractory to or are not using erythropoiesis-stimulating agents. The purpose of the study is to determine whether oral rigosertib treatment results in hematological improvements according to the 2006 International Working Group criteria in these patients. The study will also record any side effects that may occur during the study.