A new experimental breast cancer vaccine has been proven to make mice reject tumors, including cancers that are no longer sensitive to Herceptin. This new vaccine targets breast cancers that grow wildly in reponse to the growth factor named HER-2. Approximately 25% of women that have breast cancer have HER-2 positive tumors. The medication Herceptin, which is a man-made antibody for treatment for patients with breast cancer, targets these specific cancers. However, after some time these tumor cells often become resistant to Herceptin.

Wei-Zen Wei (PhD), who is a professor of immunology at Detroit’s Karmanos Cancer Insitute, said that the experimental vaccine elicits immune responses that terminate HER-2 postitive breast tumors in mice, whether or not the cells have become resistant to Herceptin. “Regardless of whether tumor cells are resistant, if immune cells are properly primed by immunization we can destroy these cells.”

Wei and his team developed this new vaccine which uses DNA that carries the genetic code for a very important piece of the HER-2 molecule. After an injection of this DNA into the skin, a small electric pulse is administered to help the cells absorb the DNA and produce the protein which elicits immune responses. The mice that were given the vaccine made anti-HER-2 antibodies. The new vaccine also primed cellular immune responses that attacked the breast cancer tumors. The responses to cells alone were enough to terminate the HER-2 positive cells in the mice that were unable to make antibodies.

A version of this new vaccine is now undergoing safety tests in humans.

In April of 2007, a different HER-2 vaccine made the headlines when it cut the number of deaths in women with HER-2 positive breast cancer in half. That particular vaccine also slowed down the recurrence of breast cancer. However, the researchers from San Antonio’s Brooke Army Medical Center found that after 26 months of receiving the vaccination, there was no significant difference in the recurrence of the cancer between the women who were vaccinated and the women who did not receive the vaccination.

Gary Yang, MD, who is an associate professor of radiation medicine at the Rosewell Park Cancer Institute in Buffalo, N.Y., said that these studies on humans are a major step forward. “These studies accomplished a lot—but we need to find out why the immune system cannot sustain this efficacy.”

Yang stated that this is why Wei’s team’s research is so important. What we learn in the lab must eventually be tested in patients, and then more lab work will be needed to answer question that will be raised by the human studies. He also said,” The clinical research into breast cancer vaccines is not going to be a home run.”

Wei is certain that in the long run, there will be vaccines created that will prove to be power cancer treatments. She stated that,” Ultimately, we will be using the best defense we have to fight cancer — the human immune system.” This is a very challenging thing to accomplish, but we hope that we have reached a point where we can make this useful to patients with breast cancer.

The findings for the research of this study conducted by Wei and her team can be found in the September 15th issue of Cancer Research.

Women’s Health – Hopes Raised for Breast Cancer Vaccine | Health News