Vaccine for Breast Cancer Seems Promising

SAN ANTONIO, Dec. 15 -- An investigational breast cancer vaccine consistently reduced the rate of disease recurrence by about 50%, according to combined results of two small non-randomized studies, researchers reported here.

The vaccine, based on the HER2/neu protein, shows sufficient promise that researchers are seeking approval for a phase III randomized trial, said Col. George Peoples, M.D., of Brooke Army Medical Center in Fort Sam Houston, Tex.

The finding was "very exciting to us," Dr. Peoples told a plenary session of the San Antonio Breast Cancer Symposium, but he added that because of the small numbers the difference lost statistical significance in the most recent analysis.

The researchers enrolled 186 women with completely treated breast cancer, who were disease-free when they entered the trial and had an intact immune system, Dr. Peoples said. Both node-positive and node-negative women were enrolled.

The vaccine was a peptide dubbed E75, derived from the HER2/neu protein and combined with granulocyte macrophage colony simulating factor (GM-CSF) and was injected intradermally, Dr. Peoples said.

The peptide binds to the HLA A2 molecule, found in about half the population, and stimulates CD8 killer cells, he said. Women in the studies served as controls -- and were not vaccinated -- if they did not have the HLA A2 molecule.

After a median 20 months of follow-up, Dr. Peoples said:

• Overall survival was 99% among vaccinated women and 95% among controls.
• Disease-free survival was 92.5% for those who were vaccinated and 77% among controls.
• The recurrence rate was 5.7% among the vaccinated women and 14.1% among the controls, which was statistically significant at P