Exploratory biomarker analysis of trastuzumab deruxtecan (T-DXd) vs physician’s choice of chemotherapy (TPC) in HER2-low/ultralow, hormone receptor–positive (HR+) metastatic breast cancer (mBC) in DESTINY-Breast06 (DB-06) - Dent, RA; Curigliano, G; Hu, X (J Clin Oncol, 2025)