(HealthDay News) — Patients with breast cancer who are vaccinated with AE37, the Ii-Key hybrid of the human epidermal growth factor receptor 2 (HER2)-derived peptide, together with the immunoadjuvant granulocyte macrophage colony-stimulating factor (GMCSF), have significant immune responses compared with those vaccinated with GMCSF alone, according to a Phase 2 study presented at the annual meeting of the American Association for Cancer Research, held from March 31 to April 4 in Chicago.
Diane F. Hale, MD, of Brooke Army Medical Center in Fort Sam Houston, TX, and colleagues randomized disease-free, node-positive or high-risk node negative breast cancer patients with any level of HER2 expression to AE37+GMCSF (vaccine group [VG]; 109 patients) or GMCSF (control group [CG]; 108 patients) intradermal inoculations. Specific immunologic responses were assessed.
The researchers found that the in vitro proliferation responses, measured using the [3H]-thymidine incorporation assay, classified 33% of VG and 7.4% of CG as high responders (P<0.001); 17.4 and 14.8%, respectively, as low responders (P=0.600); and 49.5 and 77.8%, respectively, as non-responders (P<0.001). Based on in vivo delayed-type hypersensitivity reactions, 86% of VG and 27% of CG were classified as responders (P=0.0001), and 14 and 73%, respectively, were classified as non-responders (P<0.001). The percentage of patients who had a decrease in their T regulatory cells (Tregs) was significantly higher in the VG group (73.2 vs. 54.9%; P=0.048).
“VG patients had significant immunologic responses compared to CG,” the authors write. “Monitoring immunologic tests and Tregs throughout the vaccination process may stratify patients into responders and non-responders and thus assist in identifying patients that will have recurrence.”