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Oncol."],"abstract":"<jats:p>Breast cancer is the most common malignancy among women worldwide, and hormone receptor-positive (HR+)\/human epidermal growth factor receptor 2 (HER2)-low breast cancer poses significant challenges once resistance to endocrine therapy and CDK4\/6 inhibitors develops. We present a 45-year-old female patient with HR+\/HER2-low metastatic breast cancer who progressed on standard-of-care treatments. The combination of trastuzumab deruxtecan and fulvestrant demonstrated significant clinical efficacy and favorable tolerability, achieving a progression-free survival of 26 months with no grade 3 or higher adverse events observed. This case suggests that this combination may represent a promising therapeutic strategy for patients with advanced, treatment-refractory HR+\/HER2-low breast cancer, offering a useful reference for clinical practice.<\/jats:p>","DOI":"10.3389\/fonc.2026.1957375","type":"journal-article","created":{"date-parts":[[2026,9,14]],"date-time":"2026-09-14T04:38:38Z","timestamp":1789360718000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: Trastuzumab deruxtecan combined with fulvestrant in a patient with HR+\/HER2-low metastatic breast cancer"],"prefix":"10.3389","volume":"16","author":[{"given":"Jiaying","family":"Chai","sequence":"first","affiliation":[{"name":"Department of Oncology, Shenzhen Hospital, Southern Medical University","place":["Shenzhen, China"]},{"name":"Shenzhen School of Clinical Medicine, Southern Medical University","place":["Shenzhen, 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