(7α,17β)-7-[9-[4,4,5,5,5-Pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol; Faslodex; Fulvestrant; ICI 182780; ZD 182780; ZD 9238; ZM 182780

Fulvestrant is a selective estrogen receptor degrader (SERD) that downregulates and degrades estrogen receptor α (ERα).1,2 It binds to rat uterine ER with an IC50 value of 44.8nM and prevents uterine weight increases induced by estradiol in immature rats (ED50> = 0.06mg/kg per day) but has no effect on uterine weight alone.3 It also decreases uterine weight in adult rats without affecting the production of luteinizing and follicle-stimulating hormones and prolactin. Fulvestrant inhibits the growth of ER-positive MCF-7 human breast cancer cells but not ER-negative BT-20 cells when used at a concentration of 1ug/ml. It also prevents tumor growth in MCF-7 and Br10 breast cancer mouse xenograft models when used at a single dose of 5mg per animal. Fulvestrant is neuroprotective in vitro against neurotoxicity induced by glutamate- and amyloid-β (1-42) (Aβ42) in primary rat hippocampal cells.4 Formulations containing fulvestrant have been used in the treatment of estrogen-sensitive breast cancer.