Date of presentation: September 14, 2012
An investigational vaccine known as AE37 may reduce the risk of cancer recurrence among women who have been treated for early-stage, triple-negative breast cancer. The results of this Phase II clinical trial were presented at the 2012 Breast Cancer Symposium.
For women with breast cancer, tests for a protein known as HER2 play an important role in treatment decisions. Breast cancers that have high levels of HER2 are considered to be “HER2-positive.” These cancers often respond to treatment with the HER2-targeted drug Herceptin® (trastuzumab). HER2-negative cancers, in contrast, have lower levels of HER2 and usually do not respond to treatment with Herceptin.
AE37 is an investigational, anti-cancer vaccine. It is intended to prompt a response by the immune system against cells that express the HER2 protein. If it proves to be effective, it could benefit women whose HER2 levels are too low to warrant treatment with Herceptin.
To explore the safety and efficacy of the AE37 vaccine, researchers conducted a Phase II clinical trial among women with early-stage breast cancer that showed at least some evidence of HER2 (IHC 1+ to 3+). This includes women with HER2 levels that are low enough to be considered HER2-negative.
Women were enrolled in the study after they had undergone standard breast cancer treatment and been found to be cancer-free. Some women received the AE37 vaccine and the other women formed the comparison group. The vaccine was given once a month for six months. This was followed by booster doses given every six months.
At the time of this preliminary analysis, study participants had been followed for roughly three years.
- The vaccine appeared to improve outcomes, particularly among women with low HER2. Among women with triple-negative breast cancer, for example, disease-free survival (survival without a recurrence or new cancer) was 83% among women in the vaccine group and 52% among women in the comparison group. The difference between groups did not meet the criteria for statistical significance, however, suggesting that it could have occurred by chance alone.
Although these results are not definitive, they suggest that the AE37 vaccine may improve outcomes among women with low levels of HER2, including women with triple-negative breast cancer. Women in this study will continue to be followed, and planning is underway for a larger, Phase III clinical trial.