The present invention relates to the use of 4-(4-Fluoro-2-methoxyphenyl)-N-{3-[(S-methylsulfonimidoyl)methyl]phenyl}-1,3,5-triazin-2-amine (compound A), more particularly (+)-4-(4-Fluoro-2-methoxyphenyl)-N-{3-[(S-methylsulfonimidoyl)methyl]phenyl}-1,3,5-triazin-2-amine (compound A), for treating leukemias, in particular acute leukemias, preferably acute myeloid leukemias.本發明係關於4-(4-氟-2-甲氧苯基)-N-{3-[(S-甲磺醯亞胺醯基)甲基]苯基}-1,3,5-三-2-胺(化合物A),更特定言之(+)-4-(4-氟-2-甲氧苯基)-N-{3-[(S-甲磺醯亞胺醯基)甲基]苯基}-1,3,5-三-2-胺(化合物A)之用途,其用於治療白血病,特定言之急性白血病,較佳為急性骨髓性白血病。