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Vaccine benefited patients with low expression of HER-2 tumors
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Vaccination with the hybrid peptide AE37 demonstrated clinical benefit in patients with breast cancer, particularly those who have low HER-2–expressing tumors, according to early results of a randomized phase 2 study.
Peptide vaccines composed of HLA class II epitopes, which elicit CD4+ T-cell responses, play a key role in powering immune responses.
Results of a phase 1 study showed that when AE37 (Generex) was combined with the protein granulocyte-macrophage colony–stimulating factor, it safely and effectively caused HER-2–specific immunity, according to background information provided by researchers.
In the phase 2 study, Elizabeth Ann Mittendorf, MD, assistant professor in the department of surgical oncology at The University of Texas MD Anderson Cancer Center, and colleagues examined outcomes in patients with low HER-2–expressing tumors and triple-negative breast cancer.
To date, Mittendorf and colleagues have enrolled 281 patients with node-positive or high-risk node-negative breast cancer with any degree of HER-2 expression who have been rendered disease-free after standard therapy.
The researchers randomly assigned patients to AE37 and GM-CSF (n=115) or GM-CSF alone (n=166). Patients received six monthly intradermal inoculations, followed by booster inoculations administered every 6 months.
After a median follow-up of 28.4 months, researchers observed a higher rate of DFS among patients assigned to AE37 vaccination (90.1% vs. 83%; P=.33), equating to a risk reduction of 42%.
Among patients with low HER-2 expression, the DFS rate for patients assigned to AE37 vaccination was significantly higher than that for patients assigned to GM-CSF alone (88.7% vs. 70.3%; P=.12), equating to an overall risk reduction of 62%.
The study included 40 patients with triple-negative breast cancer, 14 of whom were assigned to the vaccine group and 26 of whom were assigned to GM-CSF alone. Among patients with triple-negative breast cancer, the DFS rate for those assigned to the vaccine was 83.3% compared with 51.5% for those assigned to GM-CSF alone (P=.26), equating to an overall risk reduction of 66%.
Mittendorf and colleagues will continue to follow patients for 5 years.
“These data suggest that a subsequent phase 3 trial should evaluate the [AE37] vaccine in patients with low HER-2–expressing disease, to include [patients with] triple-negative breast cancer,” Mittendorf and colleagues concluded.
For more information:
Mittendorf EA. Abstract #109. Presented at: 2012 Breast Cancer Symposium; Sept. 13-15, 2012; San Francisco.
Disclosure: The researchers report receiving research funding from and serving as consultants for Antigen Express.
Perspective
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Sylvia Adams, MD
Researchers want to see if the patients who receive the vaccine have a longer DFS than patients who receive adjuvant therapy alone. Both treatment arms are getting some therapy. Therefore, the control arm is a bit weak because there is an adjuvant given. The current data do not yet support that this is significantly improving the outcomes for the patients. The data are promising, and hopefully in the future there will be a statistically clinical benefit. The study does not report a clear state of the tumors — only detailing the tumor size and lymph node positivity or negativity. The study does not have the data to say whether the arms are well-balanced. Having said that, it is important to follow the patients long term to see if these results prove to be significant.
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