AZD9496 maleate

AZD9496 maleate is a potent and selective estrogen receptor (ERα)antagonist with IC50 of 0.28 nM. IC50: 0.28 nM (ERα antagonism), 0.14 nM (ERα downregulation), 0.82 nM (ERα binding)[1]

The potency of AZD9496 with IC50 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 EC50 of 0.04 nM[1]. Selectivity of AZD9496 over other tested nuclear hormone receptors is high: androgen receptor (AR), IC50=30 μM; glucocorticoid receptor (GR), IC50=9.2 μM; progesterone receptor (PR), IC50=0.54 μM[2].

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 fulvestrant control (P<0.001) but significantly lower than tamoxifen (P=0.001)[1]. AZD9496 is also tested in a long-term estrogen deprived model (LTED), using the HCC-1428 LTED cell line that grows in the absence of estrogen and is thought to best represent a model of aromatase inhibition. AZD9496 shows significant activity, with a dose of 5 mg/kg giving tumor regressions in this model[2].

[1]. Weir HM, et al. AZD9496: An Oral Estrogen Receptor Inhibitor That Blocks the Growth of ER-Positive and ESR1-Mutant Breast Tumors in Preclinical Models. Cancer Res. 2016 Jun 1;76(11):3307-18. [2]. De Savi C, et al. Optimization of a Novel Binding Motif to (E)-3-(3,5-Difluoro-4-((1R,3R)-2-(2-fluoro-2-methylpropyl)-3-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-yl)phenyl)acrylic Acid (AZD9496), a Potent and Orally Bioavailable Selective Estrogen Receptor Downregulator and Antagonist. J Med Chem. 2015 Oct 22;58(20):8128-40.