BACKGROUND: The purpose of this study was to determine the safety and immune responses of pre-operative personalized peptide vaccine for patients with localized prostate cancer. METHOD: Ten human leukocyte antigen (HLA)-A24(+) patients with localized prostate cancer received weekly personalized peptide vaccine for six times with positive peptides (up to four kinds of peptides) from 16 kinds of vaccine candidates, followed by a retropubic radical prostatectomy (RRP). Eight patients with localized prostate cancer receiving RRP served as the control group. The serum prostate-specific antigen (PSA) level, and peptide-specific cytotoxic T lymphocyte (CTL) precursor analysis by interferon-gamma production, and peptide-reactive immunoglobulin G (IgG) using an enzyme-linked immunosorbent assay were monitored during the treatment. Distributions of CD45RO(+) cells, CD8(+) T cells, and CD20(+) B cells in tissue microarray samples were studied using an immunohistochemical technique. RESULT: The peptide vaccination was safe and well tolerated with no major adverse effects. Increased CTL response and the anti-peptide IgG titer were observed in the post-vaccination samples in 8 of 10 or 8 of 10 patients, respectively. The intensity of CD45RO(+) infiltrating cells in the vaccination group was significantly larger than that in the control group. CD8(+) T cell infiltration was seen only in the vaccinated group. CONCLUSION: Increased immune responses, at both the circulation and tumor sites in the vaccinated group, support the further development of personalized peptide vaccines for patients with localized prostate cancer.
BACKGROUND: The purpose of this study was to determine the safety and immune responses of pre-operative personalized peptide vaccine for patients with localized prostate cancer. METHOD: Ten human leukocyte antigen (HLA)-A24(+) patients with localized prostate cancer received weekly personalized peptide vaccine for six times with positive peptides (up to four kinds of peptides) from 16 kinds of vaccine candidates, followed by a retropubic radical prostatectomy (RRP). Eight patients with localized prostate cancer receiving RRP served as the control group. The serum prostate-specific antigen (PSA) level, and peptide-specific cytotoxic T lymphocyte (CTL) precursor analysis by interferon-gamma production, and peptide-reactive immunoglobulin G (IgG) using an enzyme-linked immunosorbent assay were monitored during the treatment. Distributions of CD45RO(+) cells, CD8(+) T cells, and CD20(+) B cells in tissue microarray samples were studied using an immunohistochemical technique. RESULT: The peptide vaccination was safe and well tolerated with no major adverse effects. Increased CTL response and the anti-peptide IgG titer were observed in the post-vaccination samples in 8 of 10 or 8 of 10 patients, respectively. The intensity of CD45RO(+) infiltrating cells in the vaccination group was significantly larger than that in the control group. CD8(+) T cell infiltration was seen only in the vaccinated group. CONCLUSION: Increased immune responses, at both the circulation and tumor sites in the vaccinated group, support the further development of personalized peptide vaccines for patients with localized prostate cancer.