Fulvestrant

Fulvestrant (Faslodex) is a new estrogen receptor (ER) antagonist for the treatment of advanced breast cancer. It binds competitively to the oestrogen receptor (ER), with high affinity, and downregulates ER by functional blockade and increased turnover. Fulvestrant is a potent inhibitor of the growth of human breast cancer cells in vitro and in vivo. It has demonstrated pure anti-estrogenic activity in animal systems. Fulvestrant is an estrogen receptor antagonist with no agonist effects, which works both by down-regulating and by degrading the estrogen receptor. Because of a different mode of action to that of other hormonal agents, fulvestrant is effective in the treatment of tamoxifen-resistant disease and, unlike tamoxifen, has no known estrogen agonist effects.