Taiwan expert consensus on the clinical integration of antibody-drug conjugates in advanced breast cancer

<h2>Abstract</h2><h3>Background</h3> Antibody–drug conjugates (ADCs) have emerged as potent targeted therapies in advanced breast cancer, offering new options across HER2-positive, HR-positive/HER2-negative, and triple-negative subtypes. To address the rapidly evolving evidence, the Taiwan Breast Cancer Society (TBCS) convened an expert panel to develop consensus guidelines for integrating ADCs into clinical practice. <h3>Methods</h3> A multidisciplinary panel conducted systematic literature review and iterative discussions, identifying nine key topics. They formulated 31 consensus statements, graded by level of evidence and strength of recommendation, all of which reached ≥85% agreement. <h3>Results</h3> Trastuzumab deruxtecan (T-DXd) is recommended as the preferred second-line treatment for HER2-positive metastatic breast cancer, with T-DM1 as an alternative when T-DXd is unavailable. T-DXd retains efficacy in HER2-low disease and brain metastases. In HR-positive/HER2-negative MBC, both T-DXd and sacituzumab govitecan (SG) improve outcomes after endocrine therapy and CDK4/6 inhibitors, regardless of HER2-low (IHC 1+/2+) or IHC 0 status. In triple-negative breast cancer, SG offers significant survival benefit in refractory cases. There is currently no evidence supporting routine sequential use of multiple ADCs. <h3>Conclusions</h3> The TBCS guideline provides practical recommendations for integrating ADCs into the treatment of advanced breast cancer based on current evidence. It supports biomarker-guided agent selection across subtypes and highlights the need for continued research on sequencing strategies and optimal clinical positioning.