An experimental vaccine against the HER2/neu protein reduced the likelihood of cancer recurrence among women with node-positive breast cancer, according to a study published in the Journal of Clinical Oncology.
Several types of cancer cells, including breast cancer cells, have been found to produce high levels of the protein HER2/neu. In cancers that express HER2/neu, the protein is present on the surface of cancer cells and can be recognized by the body’s immune system. Researchers are therefore exploring whether vaccines against specific parts of this protein will effectively target and control cancer growth.
An experimental vaccine under evaluation targets the E75 component of HER2/neu. In order to assess the safety of this vaccine among women with breast cancer, and to describe the immune response that follows vaccination, researchers conducted a clinical study among 53 women who had been treated for node-positive breast cancer. The vaccine was given to the 24 women who were most likely to respond to the vaccine based on their human lymphocyte antigen (HLA) type. The remaining 29 women served as an unvaccinated comparison group.
All the vaccinated women demonstrated an immune response to the vaccine. One patient reported severe bone pain after vaccination, but there were no other serious adverse effects.
After roughly 22 months of follow-up, the study reflected the following results:
- 86% of vaccinated patients were alive and free of breast cancer, compared to 60% of unvaccinated subjects.
- 8% of vaccinated subjects experienced a cancer recurrence compared to 21% of unvaccinated subjects.
- The only two deaths in the study occurred among unvaccinated women.
- The survival advantage among vaccinated women occurred in spite of an initially worse prognosis in this group; the women who were vaccinated had been treated for breast cancers that were larger and less likely to be hormone-sensitive than the women who were not vaccinated.
The researchers conclude that the HER2/neu (E75) vaccine is safe and produces an immune response. The vaccine appears to reduce risk of recurrence among women with node-positive breast cancer, but additional studies are necessary to confirm a benefit.
Patients with breast cancer may wish to talk with their doctor about the risks and benefits of participating in a clinical trial further evaluating this or other therapeutic approaches. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (www.cancer.gov) and www.cancerconsultants.com.
Reference: Peoples GE, Burney JM, Hueman MT et al. Clinical trial results of a HER2/neu (E75) vaccine to prevent recurrence in high-risk breast cancer patients. Journal of Clinical Oncology. Early online publication September 12, 2005.
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