[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"health-study-detail:100645729":3},{"organization":4,"armGroups":7,"interventions":14,"overallOfficials":10,"centralContacts":20,"locations":10,"responsibleParty":26,"collaborators":28,"id":32,"slug":33,"hasResults":34,"nctId":35,"briefTitle":36,"officialTitle":37,"acronym":38,"eligibilityCriteria":39,"healthyVolunteers":34,"sex":40,"minAge":41,"maxAge":42,"enrollmentInfo":43,"targetDuration":10,"studyType":46,"phases":10,"briefSummary":47,"conditions":48,"keywords":10,"overallStatus":50,"whyStopped":10,"lastUpdateSubmitDate":51,"lastUpdatePostDateStruct":52,"startDateStruct":55,"completionDateStruct":57,"leadSponsor":59,"locationsCount":10},{"fullName":5,"class":6},"AstraZeneca","INDUSTRY",[8],{"label":9,"type":10,"description":11,"interventionNames":12},"Participants with HR-positive, HER2-negative advanced breast cancer",null,"Adults with HR-positive, HER2-negative advanced breast cancer receiving first-line therapy with an aromatase inhibitor plus a CDK4\u002F6 inhibitor for 6 to 18 months without disease progression at study entry. Participants undergo baseline ESR1 mutation testing using circulating tumour DNA; those with a negative baseline result may undergo follow-up testing approximately every 3 months for up to 18 months.",[13],"Other: Blood sampling",[15],{"type":16,"name":17,"description":18,"armGroupLabels":19,"otherNames":10},"OTHER","Blood sampling","Blood sampling for ctDNA-based ESR1 mutation testing, which are associated with minimal additional risk and burden compared with routine clinical practice",[9],[21],{"name":22,"role":23,"phone":24,"phoneExt":10,"email":25},"AstraZeneca Clinical Study Information Center","CONTACT","+1877240-9479","information.center@astrazeneca.com",{"type":27,"investigatorFullName":10,"investigatorTitle":10,"investigatorAffiliation":10,"oldNameTitle":10,"oldOrganization":10},"SPONSOR",[29],{"name":30,"class":31},"Food and Drug Administration (FDA)","FED","100645729","shield-surveillance-of-hrher2---implementing-esr1m-long-term-monitoring-and-detection-in-1l-abc-100645729",false,"NCT07701070","SHIELD: Surveillance of HR+\u002FHER2- : Implementing ESR1m Long-term Monitoring and Detection in 1L aBC","A Multicenter Study to Describe the Frequency and Emergence of ESR1 Mutations in Patients With Hormone Receptor-Positive Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer Receiving First-Line Endocrine Based Therapy","SHIELD","Inclusion Criteria:\n\n* Age 18 years or older at the time of informed consent and willing and able to provide informed consent before any study-related procedures.\n* Histologically- or cytologically-confirmed hormone receptor-positive (ER- and\u002For progesterone receptor-positive), human epidermal growth factor receptor 2-negative (HER2-negative) advanced breast cancer.\n* Receiving first-line therapy with an aromatase inhibitor in combination with a CDK4\u002F6 inhibitor for at least 6 months and no more than 18 months, with no evidence of disease progression at study entry, as assessed by the investigator.\n* Able and willing to provide a blood sample for circulating tumour DNA testing for ESR1 mutation assessment at approximately quarterly intervals.\n\nExclusion Criteria:\n\n* Evidence of disease progression during first-line aromatase inhibitor plus CDK4\u002F6 inhibitor therapy, based on investigator assessment.\n* Known ESR1 mutation status at study entry.","ALL","18 Years","130 Years",{"count":44,"type":45},3000,"ESTIMATED","OBSERVATIONAL","This is a multicountry, multicenter, observational study in patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer receiving first-line endocrine-based therapy with an aromatase inhibitor in combination with a CDK4\u002F6 inhibitor. The study aims to describe the prevalence of ESR1 mutations at baseline and the emergence of ESR1 mutations over time using circulating tumor DNA testing in routine clinical practice.\n\nPatients receiving first-line treatment for at least 6 months and no more than 18 months, without evidence of disease progression at study entry, may undergo baseline ESR1 mutation testing. Patients with a negative baseline result may undergo longitudinal monitoring approximately every 3 months, for up to 18 months or 6 testing timepoints, to assess emergence of ESR1 mutations. The study will also describe mutation subtypes, testing methods used in routine practice, selected clinical characteristics, and treatment patterns across participating countries.",[49],"Advanced Breast Cancer","NOT_YET_RECRUITING","2026-07-08",{"date":53,"type":54},"2026-07-14","ACTUAL",{"date":56,"type":45},"2026-09-30",{"date":58,"type":45},"2029-03-30",{"name":5,"class":6}]