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.