Described are methods and compositions for treating cancer that include a dopamine receptor (DR) antagonist such as thioridazine and a chemotherapeutic agent. Optionally, the chemotherapeutic agent is a DNA synthesis inhibitor such as cytarabine or a microtubule inhibitor such as paclitaxel or docetaxel. The methods and compositions are useful for the treatment of cancers such as acute myeloid leukemia.