Academic Journal
Real-world treatment patterns and clinical outcomes in patients with emerging estrogen receptor 1 (ESR1)-mutated ER+ metastatic breast cancer in the U.S., 2018-2024.
| Τίτλος: | Real-world treatment patterns and clinical outcomes in patients with emerging estrogen receptor 1 (ESR1)-mutated ER+ metastatic breast cancer in the U.S., 2018-2024. |
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| Συγγραφείς: | Meisel JL; Department of Hematology and Medical Oncology, Emory Winship Cancer Institute, Emory University, Atlanta, GA, USA., Chen C; AstraZeneca, Gaithersburg, MD, USA., Kris A; Flatiron Health, New York, NY, USA., Ru M; AstraZeneca, Gaithersburg, MD, USA., Pham T; AstraZeneca, Gaithersburg, MD, USA., Roose J; Flatiron Health, New York, NY, USA. james.roose@flatiron.com. |
| Πηγή: | Breast cancer research and treatment [Breast Cancer Res Treat] 2026 Sep 09; Vol. 219 (2). Date of Electronic Publication: 2026 Sep 09. |
| Τύπος έκδοσης: | Journal Article; Observational Study |
| Γλώσσα: | English |
| Στοιχεία περιοδικού: | Publisher: Kluwer Academic Country of Publication: Netherlands NLM ID: 8111104 Publication Model: Electronic Cited Medium: Internet ISSN: 1573-7217 (Electronic) Linking ISSN: 01676806 NLM ISO Abbreviation: Breast Cancer Res Treat Subsets: MEDLINE |
| Imprint Name(s): | Publication: Dordrecht : Kluwer Academic Original Publication: The Hague ; Boston : M. Nijhoff, c1981- |
| Ιατρικοί όροι (MeSH): | Estrogen Receptor alpha*/genetics , Breast Neoplasms*/genetics , Breast Neoplasms*/drug therapy , Breast Neoplasms*/pathology , Breast Neoplasms*/mortality , Mutation*, United States/epidemiology ; Biomarkers, Tumor/genetics ; Humans ; Female ; Retrospective Studies ; Middle Aged ; Aged ; Treatment Outcome ; Adult ; Neoplasm Metastasis |
| Περίληψη: | Purpose: Clinical studies have highlighted the potential utility of monitoring for Estrogen receptor alpha 1 (ESR1) mutation (m) (ESR1m) emergence during first-line therapy (1L) for metastatic breast cancer (mBC). However, less is known about the real-world practice for patients with emergent ESR1m before progression and their outcomes. This study aimed to characterize real-world treatment patterns among patients with mBC who underwent ESR1m mutation testing during first-line (1L) therapy, and to evaluate the association between ESR1m detection during 1L and clinical outcomes. Methods: This retrospective, observational cohort study used the US-based, deidentified Flatiron Health Research Database and included patients diagnosed with ER+/human epidermal growth factor receptor 2-negative (HER2-) metastatic BC between 2018 and June 2024. rwOS and rwPFS were estimated using the Kaplan-Meier methodology and compared after propensity score matching. Clinical outcomes were evaluated from the time of first ESR1 test during 1L therapy to minimize time-related bias. Results: 7772 patients who initiated 1L therapy were included. Treatment patterns in 1L were comparable between patients with (n = 240) and without (n = 1095) ESR1m detected during 1L. Among patients tested for ESR1m mutations during 1L, detection of ESR1m was associated with significantly shorter rwPFS and OS from the time of testing, both before and after propensity score matching (rwPFS hazard ratio [HR] 0.68 [95%CI: 0.48-0.96], rwOS HR: 0.58 [95%CI: 0.36-0.95]). Conclusions: Detection of ESR1m during 1L was associated with poorer clinical outcomes. These findings highlight the clinical relevance of ESR1m emergence prior to progression and underscore the need for strategies to better identify and manage patients with emerging endocrine resistance. Clinical Trial: Not applicable. (© 2026. The Author(s).) |
| Competing Interests: | Declarations. Ethical approval: Not applicable. Prior disclosures of these data: SABCS 2025. Data access statement: The data that support the findings of this study were originated by and are the property of Flatiron Health, Inc. Requests for data sharing by license or by permission for the specific purpose of replicating results in this manuscript can be submitted to PublicationsDataAccess@flatiron.com. Competing interests: James Roose is employed by Flatiron Health, Inc., an independent member of the Roche Group, and owns stock in Roche. Ayush Kris is employed by Flatiron Health, Inc., an independent member of the Roche Group. Timothy Pham was employed by AstraZeneca at the time of this study. Clara Chen is employed by AstraZeneca. Meng Ru is employed by AstraZeneca. Jane Meisel has served in a consulting or advisory role for Novartis, AstraZeneca, Genentech, Seagen, Olema Oncology, GE Healthcare, Pfizer, Stemline Therapeutics, and Sermonix Pharmaceuticals, and has received institutional research funding from Pfizer, Seagen, Sermonix Pharmaceuticals, Olema Oncology, and AstraZeneca. |
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| Contributed Indexing: | Keywords: Running title; Treatment Patterns and outcomes in ESR1m mBC |
| Substance Nomenclature: | 0 (Estrogen Receptor alpha) 0 (ESR1 protein, human) 0 (Biomarkers, Tumor) |
| Entry Date(s): | Date Created: 20260909 Date Completed: 20260909 Latest Revision: 20260927 |
| Update Code: | 20260927 |
| PubMed Central ID: | PMC13558349 |
| DOI: | 10.1007/s10549-026-08061-w |
| PMID: | 42714671 |
| Βάση Δεδομένων: | MEDLINE |
| ISSN: | 1573-7217 |
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| DOI: | 10.1007/s10549-026-08061-w |