Compounds of formula (I) ##STR00001## wherein X is a fluorine or a chlorine atom; the methyl groups located at the 2- and 5-position of the piperazine ring are in trans-configuration to each other; Y is NH or O; R.sup.1 is selected from hydrogen, chloro, bromo, nitro, methyl or trifluoromethyl; R.sup.2 is selected from hydrogen, halo, methyl, trifluoromethyl, methoxy or trifluoromethoxy; or a pharmaceutically acceptable salt or solvate thereof;The invention also relates to pharmaceutical compositions containing a compound of formula (I) together with a pharmaceutically acceptable carrier. Included are also processes for the preparation of compounds of formula (I), as well as methods for treating mammals suffering from inflammatory, autoimmune, proliferative or hyperproliferative diseases by administering a compound having the formula (I) to said mammal.