In vitro activity: LSZ-102 is a potent, orally bioactive and selective ERα antagonist and SERD (estrogen receptor degrader) with an IC50 of 0.2 nM has the potential for the treatment of Estrogen Receptor Positive Breast Cancer. In breast cancer, estrogen receptor alpha (ERα) positive cancer accounts for approximately 74% of all diagnoses, and in these settings, it is a primary driver of cell proliferation. Treatment of ERα positive breast cancer has long relied on endocrine therapies such as selective estrogen receptor modulators, aromatase inhibitors, and SERDs. LSZ102 is a compound currently in clinical development for the treatment of ERα positive breast cancer.

Kinase Assay: LSZ-102 is a potent, orally bioavailable selective estrogen receptor degrader with an IC50 of 0.2 nM and currently in Phase I/Ib trials for the treatment of ERα positive breast cancer. LSZ-102 induces significant degradation of ERα after 24 h, when given as a 10 μM solution to MCF-7 cells. Robust inhibition of cell proliferation in MCF-7 cells is observed upon incubation with LSZ-102 with a half inhibitory concentration of 1.7 nM. Results demonstrate that LSZ-102 effectively inhibits the estrogen-induced activation of the ERE-luciferase reporter using charcoal-stripped serum treated with E2 with IC50 of 0.3 nM.

Cell Assay: Growth factors depleted MCF-7 ERE-luc cells are used and seeded (10 000 cells/well) in 96-well plates in CSS medium. After overnight incubation, cells are treated with LSZ-102 in the presence of estradiol (0.1 nM) for 24 h. Cells are then lysed and quantified for luciferase activity using Bright-Glo assay.