Endoxifen Z-isomer hydrochloride, an orally active Tamoxifen (HY-13757A) metabolite, is a selective estrogen receptor modulator with 100-fold more potency than its parent agent, Tamoxifen. Endoxifen Z-isomer inhibits PKCbeta1 kinase activity. Endoxifen Z-isomer attenuates PKCbeta1-activated AKTSer473 phosphorylation, diminishes AKT substrate phosphorylation, and induces Apoptosis. Endoxifen Z-isomer exhibits anticancer activity against hormone-resistant metastatic breast cancer[1][2][3][4].