This invention is concerned with novel polycyclic compounds of formula [I], ##STR1##

wherein ring A, ring B, R¹, R², R³, R⁴, R⁵, R⁶, X, Y, R¹, R², R³, R⁴, R⁵, R⁶, ring A, ring B and X are as defined hereinabove as well as pharmaceutically acceptable salts thereof. The compounds have anti-tumor activity and are useful for the treatment of cell proliferative disorders.