The phase I/II EMBER-1 trial (NCT04188548) is evaluating the drug as a single agent and in combination with alpelisib, abemaciclib, everolimus, trastuzumab, or abemaciclib in post-menopausal and pre-menopausal patients with advanced ER+/HER2-negative BC or endometrial endometrioid cancer. This evidence concerns the gene ESR1 and breast cancer.