Notes: ARN810 is a selective estrogen receptor degrader (SERD) that binds to ERα and ERβ (IC50s = 6.1 and 8.8 nM, respectively) and induces degradation of ERα in MCF-7 cells (EC50 = 0.7 nM).{53182} It inhibits ERα transcriptional activity induced by 17β-estradiol (Item No. 10006315) in a reporter assay and reduces MCF-7 breast cancer cell viability (IC50 = 2 nM). ARN810 (1 mg/kg, p.o.) inhibits 17β-estradiol-induced uterine weight gain in rats. It reduces tumor volume in tamoxifen-sensitive and -resistant MCF-7 mouse xenograft models in a dose-dependent manner.