The present invention provides a therapeutic composition for intractable leukemia comprising a drug (a) and a drug (b), wherein the drug (a) is a compound represented by the following formula (I), a salt thereof, or a prodrug thereof:wherein, Ar1 is a substituted or unsubstituted arylene group；Ar2 is a substituted or unsubstituted aryl group or a substituted or unsubstituted aralkyl group；L is an oxygen atom, -NHCO-, or -CONH-；X1 is CH；X2 and X3 are CH and a nitrogen atom, respectively；Y is an ethylene group；m is 0； andZ1 and Z2 form a substituted or unsubstituted monocyclic heterocyclic group comprising X3 and having two nitrogen atoms as ring members, andthe drug (b) is a steroidal anti-inflammatory drug； and relates to a therapy for intractable leukemia.
