{"groups":[{"description":"Participants received Imlunestrant 400 milligrams (mg) orally once daily on days 1 to 28 of a 28-day cycle, until disease progression or a criterion for discontinuation were met.","id":"FG000","title":"Arm A: Imlunestrant"},{"description":"Participants received the investigator's choice of endocrine therapy, either exemestane 25 mg administered orally once daily on days 1 to 28 of a 28-day cycle, or Fulvestrant 500 mg intramuscularly on days 1 and 15 of Cycle 1, then on Day 1 of Cycle 2 and beyond, until disease progression or a criterion for discontinuation was met.","id":"FG001","title":"Arm B: Investigator's Choice of Endocrine Therapy"},{"description":"Participants received Imlunestrant 400 mg orally once daily on Days 1 to 28 of a 28-day cycle, plus Abemaciclib 150 mg orally twice daily on Days 1 to 28 of a 28-day cycle, until disease progression or a criterion for discontinuation was met.","id":"FG002","title":"Arm C: Imlunestrant + Abemaciclib"}],"periods":[{"dropWithdraws":[{"reasons":[{"groupId":"FG000","numSubjects":"6"},{"groupId":"FG001","numSubjects":"16"},{"groupId":"FG002","numSubjects":"6"}],"type":"Withdrawal by Subject"},{"reasons":[{"groupId":"FG000","numSubjects":"0"},{"groupId":"FG001","numSubjects":"3"},{"groupId":"FG002","numSubjects":"1"}],"type":"Physician Decision"},{"reasons":[{"groupId":"FG000","numSubjects":"10"},{"groupId":"FG001","numSubjects":"1"},{"groupId":"FG002","numSubjects":"12"}],"type":"Adverse Event"},{"reasons":[{"groupId":"FG000","numSubjects":"65"},{"groupId":"FG001","numSubjects":"43"},{"groupId":"FG002","numSubjects":"75"}],"type":"On study treatment (Ongoing)"},{"reasons":[{"groupId":"FG000","numSubjects":"4"},{"groupId":"FG001","numSubjects":"3"},{"groupId":"FG002","numSubjects":"2"}],"type":"Protocol Deviation"}],"milestones":[{"achievements":[{"groupId":"FG000","numSubjects":"331"},{"groupId":"FG001","numSubjects":"330"},{"groupId":"FG002","numSubjects":"213"}],"type":"STARTED"},{"achievements":[{"groupId":"FG000","numSubjects":"331"},{"comment":"For analyses between Arm A and Arm B, the study was planned to analyze Arm B as a whole, regardless of whether the participants received exemestane or fulvestrant as the Investigator's Choice of Endocrine Therapy.","groupId":"FG001","numSubjects":"330"},{"groupId":"FG002","numSubjects":"0"}],"comment":"All participants who were randomly assigned to either Arm A or Arm B.","type":"Analysis Population for the Comparison Between Arm A and Arm B"},{"achievements":[{"groupId":"FG000","numSubjects":"213"},{"groupId":"FG001","numSubjects":"0"},{"groupId":"FG002","numSubjects":"213"}],"comment":"For analyses between arm C and arm A, the study was planned to include participants who were randomized to these arms concurrently.","type":"Analysis Population for the Comparison Between Arm C and Arm A"},{"achievements":[{"groupId":"FG000","numSubjects":"138"},{"groupId":"FG001","numSubjects":"118"},{"groupId":"FG002","numSubjects":"0"}],"type":"Estrogen Receptor 1 (ESR1) Mutation-Detected Population for Comparison Between Arm A and Arm B"},{"achievements":[{"groupId":"FG000","numSubjects":"326"},{"groupId":"FG001","numSubjects":"324"},{"groupId":"FG002","numSubjects":"209"}],"type":"Received at Least 1 Dose of Study Drug"},{"achievements":[{"comment":"One participant assigned to Arm C received Imlunestrant alone (i.e., did not receive abemaciclib) and was therefore included in Arm A for safety analyses.","groupId":"FG000","numSubjects":"327"},{"comment":"Investigator's Choice of Endocrine Therapy:\n\n* exemestane = 32\n* fulvestrant = 292","groupId":"FG001","numSubjects":"324"},{"groupId":"FG002","numSubjects":"208"}],"comment":"All randomised participants who received at least 1 dose of study drug. Participants were analyzed according to the study treatment they actually received.","type":"Safety Analysis Population"},{"achievements":[{"groupId":"FG000","numSubjects":"246"},{"groupId":"FG001","numSubjects":"264"},{"groupId":"FG002","numSubjects":"117"}],"comment":"Participants with progressive disease or death were considered study completers.","type":"COMPLETED"},{"achievements":[{"groupId":"FG000","numSubjects":"85"},{"groupId":"FG001","numSubjects":"66"},{"groupId":"FG002","numSubjects":"96"}],"type":"NOT COMPLETED"}],"title":"Overall Study"}],"recruitmentDetails":"The study was initially planned with participants randomized 1:1 to either arm A or arm B. Following a protocol amendment, arm C was added later, after randomization to arms A and B had already begun."}