(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 II 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, M.D., from Brooke Army Medical Center in Fort Sam Houston, Texas, 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 33.0 percent of VG and 7.4 percent of CG as high responders (P < 0.001); 17.4 and 14.8 percent, respectively, as low responders (P = 0.600); and 49.5 and 77.8 percent, respectively, as non-responders (P < 0.001). Based on in vivo delayed-type hypersensitivity reactions, 86.0 percent of VG and 27.0 percent of CG were classified as responders (P = 0.0001), and 14.0 and 73.0 percent, 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 versus 54.9 percent; P = 0.048).
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“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.”
