(SACRAMENTO, Calif.) A vaccine that targets cancer cells in combination with the drug letrozole, a standard hormonal therapy against breast cancer, significantly increased survival when tested in mice, a team of UC Davis investigators has found.
The findings will be published today in the journal Clinical Cancer Research.
"We found that the vaccine and the hormonal drug letrozole were more effective when given together," said Michael DeGregorio, UC Davis professor of hematology and oncology and principal investigator of the study. "This adds critical evidence that immunotherapy with vaccines, which has traditionally been used to prevent infectious diseases, is also a promising new approach to combating cancer."
The vaccine, known as L-BLP25 (Stimuvax), specifically targets Mucin1 glycoprotein (MUC1), an antigen that is expressed in an altered form on cancer cells. When introduced into the body, the vaccine generates an immune response by T-lymphocytes, which then recognize and destroy the tumor cells. Mice in the study were injected weekly with the vaccine -- or a placebo -- for eight weeks.
In addition to the vaccine or placebo, some mice were treated with either letrozole or tamoxifen, commonly used hormonal therapies against breast cancer. Both drugs work by blocking the effects of estrogen, which can slow or stop the growth of some types of breast cancer cells that need the hormone to grow. Although the drugs have similar actions, the benefits of the vaccine were greatest in the mice treated with letrozole; in contrast, vaccinated mice given tamoxifen actually fared worse than those given either the vaccine or tamoxifen alone.
"Hormonal drugs affect the immune system in different ways, and apparently the actions of tamoxifen prevent the vaccine from working effectively," said DeGregorio. "This highlights the importance of rigorous testing of different combinations of therapies before using them in pa
|Contact: Dorsey Griffith|
University of California - Davis Health System