The human epidermal growth factor receptor 2 (HER2) peptide AE37 vaccine did not demonstrate a benefit in patients with clinically disease-free node-positive or high-risk node-negative breast cancer with any degree of HER2 expression, a study published in the journal Annals of Oncology has shown.1
Because phase 1 studies demonstrated that AE37 administered with granulocyte macrophage colony-stimulating factor (GM-CSF) is safe and highly immunogenic, researchers sought to evaluate the vaccine’s efficacy in a phase 2 trial.
For the study, researchers enrolled 298 patients with clinically disease-free node-positive or high-risk node-negative breast cancer. Patients were eligible regardless of their HER2 expression level. Participants were randomly assigned to receive AE37 plus GM-CSF or GM-CSF alone.
Results showed that 12.4% of patients in the vaccine arm developed breast cancer recurrence compared with 13.8% in the control arm, signifying a 12% reduction in recurrence risk with the vaccine (HR, 0.885; 95% CI: 0.472-1.659; P = .70).
Further, researchers estimated that 80.8% of patients in the vaccine arm would be disease-free at 5 years compared with 79.5% of control patients.
Subgroup analyses demonstrated that among patients with HER2-expressing tumors, 5-year disease-free survival was 77.2% in vaccinated patients vs 65.7% in control patients (P = .21).
In patients with triple-negative breast cancer, disease-free survival was 77.7% and 49.0% in vaccinated and control patients, respectively (P = .12).
Due to the small sample size of patients with triple-negative breast cancer, the findings support further evaluation of the peptide vaccine in a randomized trial of patients with that subtype.
1. Mittendorf EA, Ardavanis A, Symanowski J, et al. Primary analysis of a prospective, randomized, single-blinded phase II trial evaluating the HER2 peptide AE37 vaccine in breast cancer patients to prevent recurrence [published online ahead of print March 30, 2016]. Ann Oncol. doi:10.1093/annonc/mdw150.