(+)-(2R,5S)-4-[4-cyano-3-(trifluoromethyl)phenyl]-2,5-dimethyl-N-[6-(trifluoromethyl)pyridin-3- yl]piperazine-1-carboxamide (YM580) as an orally potent and peripherally selective nonsteroidal androgen receptor antagonist.

A novel series of trans-N-aryl-2,5-dimethylpiperazine-1-carboxamide derivatives was synthesized and their androgen receptor (AR) antagonist activities and in vivo antiandrogenic effects were evaluated. Pharmacological assays indicated that compound 33 was a potent AR antagonist, and subsequent optical resolution provided (+)-(2R,5S)-4-[4-cyano-3-(trifluoromethyl)phenyl]-2,5-dimethyl-N-[6-(trifluoromethyl)pyridin-3-yl]piperazine-1-carboxamide (33a, YM580) which exhibited the most potent antiandrogenic activity. Unlike bicalutamide, compound 33a decreased the weight of rat ventral prostate in a dose-dependent manner (ED(50) = 2.2 mg/kg/day), and induced the maximum antiandrogenic effect, comparable to that of surgical castration, without significantly affecting serum testosterone levels. Compound 33a is a promising clinical candidate for prostate cancer monotherapy.