Breast cancer vaccine active against HER-2 positive tumors

A breast cancer vaccine has moved one step closer to reality after an experimental breast cancer vaccine succeeded in eradicating HER-2 positive breast cancer in mice – even destroying tumors resistant to current drugs, such as Herceptin.

The experimental vaccine, developed by Wei-Zen Wei and colleagues at Wayne State University, targets breast cancers whose growth is aided by a growth factor binding to the receptor molecule HER-2. Anti-HER drugs like Herceptin target these cancers by blocking the HER-2 receptor and thus preventing the growth factor from binding to it, however cancer cells often become resistant to the drugs.

The vaccine is made using DNA that carries the genetic code for key parts of the HER-2 receptor. Study results showed that mice given the vaccine made anti-HER-2 antibodies, and that the vaccine primed T-cells to attack breast cancer tumors. Further studies showed that the T-cell response alone was enough to eliminate HER-2 positive cancer cells. No signs of toxicity were observed throughout the study.

“As we continue our extensive research on this promising vaccine, based on the results to date, we believe this could eventually help control the spread of HER2-positive breast cancer in patients who have been resistant to other treatments, and possibly prevent HER2-positive breast cancer from occurring. The greatest power of vaccination is protection against initial cancer development, and that is our ultimate goal with this treatment,” said Professor Wei in a press release issued by Wayne State University School of Medicine.

HER-2 positive cancers account for up to 30% of all cases of breast cancer. Such cancers are more aggressive than other types of breast cancer and are more likely to reoccur after treatment.

Whittington PJ, Piechocki MP, Heng HH, Jacob JB, Jones RF, Back JB, Wei WZ. DNA Vaccination Controls Her-2+ Tumors that Are Refractory to Targeted Therapies. Cancer Res. 2008;68:7502-7511.