Elena Garralda, MD, Vall d’Hebron Institute of Oncology, Barcelona, Spain, comments on the importance of the results of the DESTINY-Breast03 trial (NCT03529110) demonstrating the efficacy of trastuzumab deruxtecan (T-DXd) over trastuzumab emtansine (T-DM1) in patients with HER2-positive metastatic breast cancer. This interview took place at the European Society for Medical Oncology (ESMO) 2021 congress.