A Phase 2 Open-Label, Single-Arm, Multicenter Trial to Evaluate the Efficacy and Safety of Elacestrant Monotherapy for the Treatment of Japanese Participants With ER+/HER2- Advanced or Metastatic Breast Cancer With ESR1-mutation Following CDK4/6 Inhibitor Therapy
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.
• Must have a histologically or cytologically proven diagnosis of adenocarcinoma of the breast with evidence of either locally advanced disease not amenable to resection or radiation therapy with curative intent or metastatic disease not amenable to curative therapy
• Female participants must be post-menopausal (as defined by the protocol)
• Must have ER+ and HER2- tumor status confirmed per local laboratory testing
• Participants must be ESR1-mutant positive determined via testing with the Guardant360 Companion Diagnostic panel test prior to enrollment
• Must have disease progression during or within 28 days of completion of prior treatment with a CDK4/6 inhibitor in combination with either fulvestrant or an aromatase inhibitor (this counts as a line of prior endocrine therapy) for metastatic breast cancer