Novel retinoic acid metabolism blocking agents endowed with multiple biological activities are efficient growth inhibitors of human breast and prostate cancer cells in vitro and a human breast tumor xenograft in nude mice.

Novel retinoic acid metabolism blocking agents (RAMBAs) have been synthesized and characterized. The synthetic features include introduction of nucleophilic ligands at C-4 of all-trans-retinoic acid (ATRA) and 13-cis-retinoic acid, and modification of terminal carboxylic acid group. Most of our compounds are powerful inhibitors of hamster liver microsomal ATRA metabolism enzyme(s).