Provided is the compound 6-ethyl-3-({3-methoxy-4-[4-(4-methylpiperazin-1-yl)piperidin-1-yl]phenyl}amino)-5-(tetrahydro-2H-pyran-4-ylamino)pyrazine-2-carboxamide or a salt thereof for use in a method for preventing and/or treating acute myelocytic leukemia or atypical chronic myelocytic leukemia.