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, Ar 1 is a substituted or unsubstituted arylene group； Ar 2 is a substituted or unsubstituted aryl group or a substituted or unsubstituted aralkyl group； L is an oxygen atom, -NHCO-, or -CONH-； X 1 is CH； X 2 and X 3 are CH and a nitrogen atom, respectively； Y is an ethylene group； m is 0； and Z 1 and Z 2 form a substituted or unsubstituted monocyclic heterocyclic group comprising X 3 and having two nitrogen atoms as ring members, and the drug (b) is a steroidal anti-inflammatory drug； and relates to a therapy for intractable leukemia.
