Trastuzumab is a type of targeted therapy drug called a monoclonal antibody. It works by ‘targeting’ specific proteins on the surface of cells.
Some cancers have too much of a protein called HER2 (human epidermal growth factor receptor 2) on the surface of their cells. These are called HER2 positive cancers. The extra HER2 proteins stimulate the cancer cells to divide and grow. Trastuzumab prevents this by locking on to the HER2 protein. This helps stop the cancer cells from dividing and growing.