Illustration of the treatment of breast cancer (mammary carcinoma) with Herceptin (Trastuzumab). Herceptin is a monoclonal antibody against a certain antigen that some breast cancer cells carry on their surface. This antigen is called HER2/NEU: It derives from the growth factor HER2 that is mutated in some tumors and thus causes over proportional growth. If cancer cells are marked by the antibody, they can be destroyed by the immune system.
