A new report has described a remarkable vaccine developed by Cleveland Clinic researchers to prevent and treat breast cancer in a mouse model. Although vaccination is most effective when applied before any disease has developed, in the case of cancer, vaccine development has focused on providing treatment against established tumors. Up until now, the problem that researchers have had difficulty in overcoming is that tumor antigens are variants of cancer patients' own proteins. This means that vaccines developed using conventional methods would in all likelihood cause devastating autoimmune complications.

The authors investigated various mouse breast cancer models in order to develop a new strategy for preventative vaccination. They selected α-lactalbumin as their target vaccine autoantigen because it is a breast-specific cell differentiation protein. Furthermore, this protein is expressed in high amounts in the majority of human breast cancers, but in normal breast tissue only during breast feeding. Vaccination based on α-lactalbumin was found to trigger an immune system reaction that provided substantial protection against the development of tumors in mouse models of breast cancer. The vaccine also inhibited the growth of existing tumors. Because α-lactalbumin is expressed only during breast feeding, vaccination-induced prevention was induced without any detectable inflammation in normal breast tissue. The authors conclude that vaccination based on α-lactalbumin may provide safe and effective protection against the development of breast cancer for women past their child-bearing years when lactation is readily avoidable and the risk of developing breast cancer is starting to increase.

In separate interviews, lead researcher Vincent Tuohy indicated that enrollment in human trials could begin next year. However, it will take approximately ten years for the vaccine to be fully developed and approved for use in women. Because the protein is linked to breast feeding, the strategy behind the new vaccine would be to vaccinate women who are over 40 years old, when the risk of breast cancer begins to rise and pregnancy is less likely. However, younger women at heightened risk for breast cancer could be offerred the vaccine as an alternative to prophylactic mastectomy.