Researchers have been working to create new treatments that use the immune response to target cancer cells. As a group, these treatments are called biological therapies or immunotherapies.
A monoclonal antibody is one type of biological therapy that is being used successfully against breast cancer. Monoclonal antibodies are molecules made in the laboratory that can latch on to specific defects in cancer cells. They work in the same way that your immune system’s antibodies do, as they recognize and respond to foreign invaders. Researchers have created breast cancer treatments that can recognize and target excess amounts of the growth-promoting protein called HER2/neu, which is found in the surface of breast cancer cells in about one out of every five cases. These are called HER2-positive cancers.
Right now, these HER2/neu-targeted monoclonal antibody therapies are used in combination with chemotherapy. Each one works slightly differently, but the idea is the same: to target cells with a specific feature and shut down their growth. These treatments include:
- Herceptin (chemical name: trastuzumab)
- Tykerb (chemical name: lapatinib)
- Perjeta (chemical name: pertuzumab)
- Kadcyla (chemical name: T-DM1 or ado-trastuzumab emtansine): Kadcyla is a little bit different in that it combines the medication Herceptin with the chemotherapy medicine emtansine. Kadcyla was designed to deliver emtansine to cancer cells in a targeted way by attaching emtansine to Herceptin. Herceptin then carries emtansine to the HER2-positive cancer cells.
Each of these medications is used in different situations, so check out Breastcancer.org’s pages on these medications for more details.
Another monoclonal antibody that has been used to treat metastatic breast cancer is Avastin (chemical name: bevacizumab). This antibody targets a protein called vascular endothelial growth factor, or VEGF, which allows cancerous tumors to create the new blood vessels they need to keep growing. In 2011, the U.S. Food and Drug Administration announced that it had removed the breast cancer indication from Avastin because the drug has not been shown to be safe and effective for that use. The medicine itself is not being removed from the market and doctors can choose to use Avastin to treat women with metastatic breast cancer if the benefits outweigh potential side effects. For more information, visit our section on Avastin. Other monoclonal antibodies that target VEGF are under investigation in clinical trials.
Other types of immunotherapies, such as vaccine therapy, are also under investigation in clinical trials for breast cancer.
Vaccine therapies for breast cancer treatment are designed to help the immune system recognize the cancer cells as a threat and launch a response. Like traditional vaccines, these vaccines are generally made from weakened or dead breast cancer cells — either your own or those cultivated in a laboratory. The hope is that once the immune system becomes aware of the antigens in the vaccine, it responds by making antibodies. These antibodies could then attack and destroy any remaining cancer cells. Later, if any new cancer cells appear, the circulating antibodies of the vaccine-educated immune system would destroy them also. Again, vaccine therapy is still being studied in clinical trials.
Visit Breastcancer.org’s Clinical Trials section for more information about searching for trials.