T-DXd improves PFS and cORR over chemo in HER2-low/ultralow HR+ mBC, regardless of PI3K, ESR1, or BRCA1/2 mutations. T-DXd rechallenge after grade 1 ILD showed high success and prolonged benefit, with low recurrence and no grade 5 events. Trastuzumab rezetecan shows strong intracranial activity in HER2+ breast cancer with brain metastases in REIN trial. Zanidatamab plus chemo showed promising responses in HER2+ and HER2-low mBC, with durable activity in a phase I trial. Higher fat mass and lower fat density linked to increased T-DXd dose reductions and toxicity in metastatic breast cancer. Dr. Nunnery weighs IV Enhertu vs oral chemo, highlighting how patient goals and QoL shape treatment decisions. Dr. Nunnery discusses HER2-low and ultralow testing and Enhertu’s role after DESTINY-Breast06 in metastatic breast cancer. Enhertu approved in the EU for HR+, HER2-low, -ultralow metastatic breast cancer, showing PFS benefit over chemotherapy. Cytology provides new insights into HER2-low metastatic breast cancer, revealing proliferative features and survival trends. A new study validates a HER2-low–focused scoring system to improve diagnostic accuracy in metastatic breast cancer. Study finds HER2-low vs HER2-zero breast cancer similar overall, but HER2-low shows better RFS if node-positive. The FDA approved trastuzumab deruxtecan for HR-positive/HER2-low metastatic breast cancer based on DESTINY-Breast06 results. The FDA granted Fast Track status to emiltatug ledadotin for advanced breast cancer following phase 1 results targeting B7-H4 Dr. Lopetegui-Lia reacts to Dr. Gatti-Mays' breast cancer panel discussion from Advancements in Oncology. Dr. Margaret Gatti-Mays delves into the topic of HER2 tumor expression in breast cancer. Dr. Margaret Gatti-Mays talks with The Oncology Brothers about the right treatments for endocrine-resistant breast cancer.