Trastuzumab Deruxtecan Benefits Patients with HER2-Low Metastatic Breast Cancer Irrespective of ER Expression

Although T-DXd had already been licensed for use in all categories of HER2 positivity, including patients with so-called HER2-low tumors (defined as having immunohistochemical score of 1+ or 2+ with non-amplified in-situ hybridization), doubts have remained about the effectiveness of this antibody drug conjugate in the subset of such patients who also have low expression of the estrogen receptor, ER (having ER expression from 1-10%). At the ESMO Breast Cancer 2023 conference a sub-study analysis of the DESTINY-Breast04 Phase III study was reported that specifically addressed this topic. OncTimesTalk reporter, Peter Goodwin, asked David Cameron, MD, about his group’s findings on the effectiveness of T-DXd in ER-low metastatic breast cancer, and about the context and overall potential of using antibody drug conjugates in breast cancer. Cameron is Professor of Oncology at Edinburgh University and a joint lead for the Edinburgh Experimental Cancer Medicine Centre.