T-DXd With or Without Bevacizumab for HER2-low Breast Cancer With Brain Metastasis

Bevacizumab is a drug that targets vascular endothelial growth factor (VEGF) and inhibits tumor angiogenesis, thereby inhibiting tumor growth and spread. In the treatment of breast cancer, Bevacizumab can be used in combination with chemotherapy to improve treatment outcomes and extend patients' progression-free survival and overall survival.

"Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate (ADC) composed of an anti-HER2 monoclonal antibody (trastuzumab), a cleavable linker, and a topoisomerase I inhibitor (an exatecan derivative). It targets and binds to HER2-positive tumor cells, internalizes, and releases cytotoxic drugs to induce DNA damage and apoptosis. It also has a bystander effect that can kill neighboring tumor cells with low HER2 expression, enhancing anti-tumor activity. T-DXd has shown significant efficacy in HER2-positive advanced breast cancer, with key clinical trials (such as DESTINY-Breast03) confirming that its progression-free survival (PFS) and overall survival (OS) are superior to traditional second-line treatments, with a median PFS reaching 28.8 months. Additionally, for HER2-low-expressing (IHC 1+ or 2+/ISH-) metastatic breast cancer (in the DESTINY-Breast04 study), T-DXd can extend PFS and OS, becoming the first targeted therapy to alter the survival outcomes of such patients."