Breast cancer vaccines: What to know about the research

Answer Section

By Mayo Clinic Staff

Researchers are making progress toward developing breast cancer vaccines. But no breast cancer vaccine is approved for routine use yet.

Breast cancer vaccines are being studied for different purposes. Researchers are looking at whether vaccines could:

• Prevent breast cancer in people at high risk.
• Treat breast cancer or help make other treatments more effective.
• Lower the risk of breast cancer coming back after treatment.

Many vaccines work by exposing the immune system to antigens. Antigens are substances the immune system can recognize and learn to target. Antigens can take many forms, including proteins or other substances found in or on cells. Some antigens are whole cells or material from cells that have been broken apart.

In a vaccine for a germ, the antigen might be a weakened or inactivated form of the germ. With cancer vaccines, the antigens are often molecules that are found in or on cancer cells. The antigen in the vaccine shows the immune system what to look for. The vaccine often also contains something that helps activate the immune system.

Some breast cancer vaccines take a different approach. A messenger RNA (mRNA) cancer vaccine doesn't contain the cancer antigen itself. Instead, the vaccine gives certain immune system cells a blueprint for making the antigen. This causes an immune response that helps the body recognize and attack cancer cells.

Vaccines are one type of Immunotherapy being studied for breast cancer. Immunotherapy helps the immune system find and kill cancer cells. Immunotherapy medicines already are used to treat triple-negative breast cancer. The use of these medicines has helped spur interest in other immunotherapy approaches for triple-negative breast cancer, including vaccines. Immunotherapy medicines haven't worked as well for many other types of breast cancer. But researchers are studying whether a vaccine might help make the medicines more effective for these cancers.

Studies testing breast cancer vaccines have been small so far. They have mostly focused on seeing whether the vaccines are safe and whether they cause a response by the immune system. These studies haven't yet proved that vaccines can lower the risk of getting breast cancer or help prevent it from coming back.

Researchers are testing breast cancer vaccines in clinical trials. If you're interested in taking part in a clinical trial, talk with your healthcare team.