Trastuzumab-Deruxtecan (T-DXd) is a medication used to treat metastatic breast cancer. It is a type of targeted therapy known as an antibody-drug conjugate. This means it combines two parts: trastuzumab, which targets specific cancer cells, and deruxtecan, which is the part that kills the cancer cells. The medication works by delivering the cancer-fighting component directly to cancer cells that have a specific protein on their surface, helping to reduce damage to healthy cells.

Metastatic Breast Cancer – A form of breast cancer that has spread beyond the breast and nearby lymph nodes to other parts of the body. The cancer cells from the original tumor break away and travel through the bloodstream or lymphatic system to form new tumors in other organs. These secondary tumors, called metastases, most commonly develop in the bones, liver, lungs, or brain. The disease typically develops gradually, with cancer cells first spreading to nearby lymph nodes before reaching distant organs. The condition can affect various body functions depending on where the cancer spreads.