Frequencies of an Immunogenic HER-2/ neu Epitope of CD8+ T Lymphocytes Predict Favorable Clinical Outcomes in Prostate Cancer.

HER-2/ neu is the human epidermal growth factor receptor 2, which is associated with the progression of prostate cancer (PCa). HER-2/ neu -specific T cell immunity has been shown to predict immunologic and clinical responses in PCa patients treated with HER-2/ neu peptide vaccines. However, its prognostic role in PCa patients receiving conventional treatment is unknown, and this was addressed in this study. The densities of CD8+ T cells specific for the HER-2/ neu (780-788) peptide in the peripheral blood of PCa patients under standard treatments were correlated with TGF-β/IL-8 levels and clinical outcomes. We demonstrated that PCa patients with high frequencies of HER-2/ neu (780-788) -specific CD8+ T lymphocytes had better progression-free survival (PFS) as compared with PCa patients with low frequencies. Increased frequencies of HER-2/ neu (780-788) -specific CD8+ T lymphocytes were also associated with lower levels of TGF-β and IL-8. Our data provide the first evidence of the predictive role of HER-2/ neu -specific T cell immunity in PCa.