1. Has previous treatment for higher-risk myelodysplastic syndromes (HR MDS) or low-blast AML with chemotherapy or other antineoplastic agents including hypomethylating agent (HMAs) such as decitabine or azacitidine. Previous treatment is permitted with hydroxyurea and with lenalidomide, except that lenalidomide may not be given within 8 weeks before the first dose of study drug.