Researchers Develop a Prototype Vaccine to Prevent Breast Cancer

A first-of-its-kind vaccine to prevent breast cancer has shown favorable results in animal models, according to a study by researchers at Cleveland Clinic's Lerner Research Institute (Cleveland, OH).

The researchers found that a single vaccination with the antigen α-lactalbumin prevents breast cancer tumors from forming in mice, while also inhibiting the growth of already existing tumors. Human trials could begin within the next year. If successful, it would be the first vaccine to prevent breast cancer.

In the study, genetically cancer-prone mice were vaccinated—half with a vaccine containing α-lactalbumin and half with a vaccine that did not contain the antigen. None of the mice vaccinated with α-lactalbumin developed breast cancer, while all of the other mice did.

The US Food and Drug Administration has approved two cancer-prevention vaccines, one against cervical cancer and one against liver cancer. However, these vaccines target viruses—the human papillomavirus (HPV) and the Hepatitis B virus (HBV)—not cancer formation.

Cancer presents a problem not posed by viruses, in terms of developing a preventive vaccine. Viruses are recognized as foreign invaders by the immune system, but cancer is not. Cancer is an over-development of the body's own cells. Trying to vaccinate against this cell over-growth would effectively be vaccinating against the recipient's own body, destroying healthy tissue.

According to Vincent Tuohy, PhD, the study's principal investigator and an immunologist in Cleveland Clinic's Lerner Research Institute, the key is to find a target within the tumor that typically is not found in a healthy person. In the case of breast cancer, Tuohy and his research team targeted α-lactalbumin, a protein that is found in the majority of breast cancers, but is not found in healthy women, except during lactation. Therefore, the vaccine can rev up a woman's immune system to target α-lactalbumin, stopping tumor formation without damaging healthy breast tissue.

The strategy would be to vaccinate women over 40, when breast cancer risk begins to increase and pregnancy becomes less likely. For younger women with a heightened risk of breast cancer, the vaccine may be an option to consider instead of prophylactic radical mastectomy.

The research was published online at http://www.nature.com/naturemedicine/ and in the June 10 issue of Nature Medicine.