Background: The safety, toxicity, and immunological response of individualized peptide vaccination or human leukocyte antigen (HLA)-A24+ hormone refractory prostate cancer (HRPC) patients in combination with a low dose of estramustine were evaluated.
Methods: Sixteen patients with HLA-A24+ HRPC were enrolled in the phase I/II study. Conducted immune monitorings for those patients were peptide-specific cytotoxic T lymphocyte (CTL) precursor analysis by interferon-gamma production and peptide-reactive immunoglobulin G (IgG) by an enzyme-linked immunosorbent assay. Clinical responses and quality of life (QOL) outcomes using a self-reported patient questionnaire were also evaluated.
Results: Vaccinations were well tolerated, but all patients developed grade 1 or 2 local redness and swelling at the injection site. There was no significant immunosuppression in most cases when the peptide and a half dose (280 mg/day) of estramustine were administrated. Augmentation of peptide-specific CTL precursors or peptide-specific IgG was observed in 10 of 14 or 7 of 14 patients at 12 weeks (peptide vaccination alone), and in 6 of 8 or 10 of 12 patients at 24 weeks (during the combination therapy), respectively. All 13 patients treated, with the combination therapy, showed a decrease of serum prostate-specific antigen (PSA) level from the baseline, including six patients with a serum PSA level decrease of >or=50%. QOL outcomes were not deteriorated during the treatment.
Conclusion: These results might encourage the further evaluation of the combination of peptide vaccination and a low dose of estramustine phosphate for HLA-A24+ HRPC patients.
Copyright (c) 2004 Wiley-Liss, Inc.