AZD9496 maleate is a potent and selective estrogen receptor ( ERα ) antagonist with IC 50 of 0.28 nM. AZD9496 maleate is an orally bioavailable selective oestrogen receptor degrader (SERD). In Vitro The potency of AZD9496 with IC 50 of 0.82 nM, 0.14 nM, and 0.28 nM in ERα binding, downregulation, and antagonism, respectively. AZD9496 significantly inhibits MCF-7 cell growth with EC 50 of 0.04 nM. Selectivity of AZD9496 over other tested nuclear hormone receptors is high: androgen receptor (AR), IC 50 =30 μM; glucocorticoid receptor (GR), IC 50 =9.2 μM; progesterone receptor (PR), IC 50 =0.54 μM. MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo Significant tumor growth inhibition is observed as low as 0.5 mg/kg dose in the estrogen-dependent MCF-7 xenograft model, where this effect is accompanied by a dose-dependent decrease in PR protein levels, demonstrating potent antagonist activity. Combining AZD9496 with PI3K pathway and CDK4/6 inhibitors lead to further growth-inhibitory effects compared with monotherapy alone. AZD9496, given once daily orally at 5 and 25 mg/kg produced statistically significant increases in uterine weight compared with the ICI 182780 control (P Form:Solid IC50& Target:IC50: 0.28 nM (ERα antagonism), 0.14 nM (ERα downregulation), 0.82 nM (ERα binding)