A 68-year-old male presents with fever for 1 week. Physical examination shows anemic appearance, no hepatosplenomegaly or lymphadenopathy. Lab results: hemoglobin 80 g/L, WBC count 2×10<sup>9</sup>/L, platelets 45×10<sup>9</sup>/L. Bone marrow examination reveals 50% myeloblasts. The treatment of choice is: