ER+/HER2- Advanced or Metastatic Breast Cancer

This is a multicenter, open-label, Phase 2 bridging study to evaluate the efficacy and safety of elacestrant in Japanese post-menopausal women and men with estrogen receptor positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) advanced or metastatic breast cancer with estrogen receptor 1 gene mutation (ESR1-mut) whose disease has relapsed or progressed on at least 1 and no more than 2 prior lines of endocrine therapy for metastatic breast cancer, which must have included cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) therapy in combination with fulvestrant or an aromatase inhibitor.