Mifepristone

An antagonist of glucocorticoid, progesterone, and androgen receptors (Kis = 0.1, 0.64, and 0.65 nM, respectively); selective for these receptors over MR, ERα, and ERβ (Kis = 640, >200, and >750 nM, respectively); inhibits R5020-stimulated alkaline phosphatase activity as well as reporter transcription stimulated by either dexamethasone or R5020 in cell-based assays (IC50s = 7, 5.9, and 1.3 nM, respectively); inhibits R1881-stimulated reporter transcription in a concentration-dependent manner; inhibits growth of 4-OHT-resistant MCF-7 breast cancer cells in vitro at 10 µM; inhibits tumor growth in an SKOV3 ovarian cancer nude mouse xenograft model at 0.5 or 1 mg per day