The present invention is related to a compound of formula (I): a pharmaceutically acceptable salt thereof, a hydrate thereof, a solvate thereof, a metabolite thereof or a prodrug thereof; for use in a method for the treatment and/or prevention of leukemia, wherein X is selected from the group consisting of N—R1, O and S; R1 is selected from the group consisting of alkyl, cycloalkyl, aryl, arylalkyl and hydrogen; R2 is selected from the group consisting of indolyl, substituted indolyl, azaindolyl and substituted azaindolyl; and R3 is selected from the group consisting of aryl, substituted aryl, unsubstituted heteroaryl, heterocyclyl and substituted heterocyclyl.