Arzoxifene, a new selective estrogen receptor modulator for chemoprevention of experimental breast cancer

Arzoxifene ([6-hydroxy-3-[4-[2-(1-piperidinyl)-ethoxy]phenoxy]-2-(4-methoxy phenyl)]benzo[b]thiophene) is a selective estrogen receptor modulator (SERM ) that is a potent estrogen antagonist in mammary and uterine tissue while acting as an estrogen agonist to maintain bone density and lower serum chol esterol. Arzoxifene is a highly effective agent for prevention of mammary c ancer induced in the rat by the carcinogen nitrosomethylurea and is signifi cantly more potent than raloxifene in this regard. Arzoxifene is devoid of the uterotrophic effects of tamoxifen, suggesting that, in contrast to tamo xifen, it is unlikely that the clinical use of arzoxifene will increase the risk of developing endometrial carcinoma.