The present invention relates to the use of a compound of formula (I) wherein R1 is H, C1-C6-alkyl, phenyl-C1-C4-alkyl or phenyl, R2 is a phenyl group which is substituted with 2 or 3 C1-C6-alkoxy groups and R3 is indolyl or azaindolyl which may carry one or two substituents independently selected from C1-C6-alkyl, C1-C6-alkoxy, phenyl, OH, halogen, NH2, C1-C6-alkylamino, di-C1-C6-alkylamino, heteroaryl with 5 or 6 ring atoms containing 1 or 2 heteroatoms which are independently selected from O, N, and S, or heterocyclyl with 5 or 6 ring atoms containing 1 or 2 heteroatoms which are independently selected from O, N, and S, a physiologically acceptable salt thereof, or a solvate of the compound of formula (I) or of the salt thereof, for the prevention or treatment of leukemia.
