Trastuzumab is a targeted therapy used primarily to treat certain types of breast cancer that overexpress the HER2 protein. It works by binding to the HER2 receptors on cancer cells, inhibiting their growth and signaling pathways, which can slow down or stop tumor progression. This medication is often used in combination with chemotherapy and is administered through an intravenous infusion. Trastuzumab has been shown to improve survival rates in patients with HER2-positive breast cancer, making it a crucial component of modern cancer treatment strategies.