Endoxifen shows anti-estrogenic effects, and decreases the E2-induced PR expression in MCF-7 cells. Endoxifen also blocks ER-alpha transcriptional activity and inhibits estrogen-induced breast cancer cell proliferation. In MCF7, HS 578T, and BT-549 cells, Endoxifen significantly inhibits cell proliferation. Endoxifen also exhibits four-fold higher inhibition on PKC activity compared to tamoxifen. Endoxifen inhibits the hERG current by preferentially interacting with the activated states of cloned hERG potassium channels with IC50 of 1.6 μM.
In vivo
In vivo, Endoxifen (8 mg/kg, ) inhibits growth of MCF-7 human mammary tumor xenografts in mice, showing more potency than Tamoxifen.
