Erika Hamilton, MD, Sarah Cannon Research Institute, Nashville, TN, discusses two big breast cancer trials from ESMO 2021: DESTINY-Breast03 (NCT03529110) and MONALEESA-2 (NCT01958021). DESTINY-Breast03 compared trastuzumab emtansine (T-DM1) to trastuzumab deruxtecan as a second-line therapy. The primary endpoint was met, with a significant improvement in progression free survival. Additionally, the incidence of adverse side effects was reduced compared to DESTINY-Breast01. MONALEESA-2 investigated ribociclib as a first-line treatment for HER2-negative, advanced breast cancer. The overall survival (OS) of these patients saw an improvement of 12.5 months, with OS increasing year-on-year in follow-ups. This interview took place at the European Society for Medical Oncology (ESMO) 2021 congress.