Method of treating leukemia, inhibiting the growth or proliferation of leukemic cells or extending the life span of a animal having leukemia are disclosed. The methods comprise the step of treating the leukemia with an effective amount of a compound of the Formula I ##STR1## or a pharmaceutically acceptable salt or prodrug form thereof, wherein: X is hydrogen, halogen or alkyl of less than 7 carbon atoms; n is a positive integer of less than 4; Y is hydrogen, chlorine, nitro, methyl or ethyl; R is hydrogen or an alkyl group of from 1 to 8 carbon atoms, alkylcarbamyl; R.sub.2 is 4-thiazolyl or NHCOOR.sub.1 ; and R.sub.1 is an aliphatic hydrocarbon of less than 7 carbon atoms. A chemotherapeutic agent and/or potentiator can be used in conjunction with the compound of the Formula I.