Immunological monitoring during combination of patient-oriented peptide vaccination and estramustine phosphate in patients with metastatic hormone refractory prostate cancer.

Background: Additive antitumor effects could be achieved by combination of immunotherapy and cytotoxic agents with no or minimum suppression.

Methods: Thirteen patients positive for human leukocyte antigen (HLA)-A24 or -A2 with metastatic hormone refractory prostate cancer (HRPC) who had failed to respond to the prior-peptide vaccination were entered in the combined peptide vaccination and estramustine phosphate. Conducted immune monitoring on those 13 patients were mainly peptide-specific cytotoxic T lymphocyte (CTL) precursor analysis by IFN-gamma productions and peptide-reactive IgG by an enzyme-linked immunosorbent assay (ELISA).

Phase I trial of patient-oriented vaccination in HLA-A2-positive patients with metastatic hormone-refractory prostate cancer.

To evaluate the safety and toxicity of peptide vaccination for patients with metastatic hormone-refractory prostate cancer (HRPC) based on pre-existing peptide-specific cytotoxic T-lymphocyte (CTL) precursors in the circulation, 10 patients positive for human leukocyte antigen (HLA)-A2 with metastatic HRPC were enrolled in a phase I study. Peptide-specific CTL-precursors reactive to 16 kinds of vaccine candidates in the pre-vaccination peripheral blood mononuclear cells (PBMCs) were measured, and patients were followed by vaccination with only positive peptides (up to 4 kinds of peptides). Serum prostate-specific antigen (PSA) levels were monitored regularly.

Induction of cellular and humoral immune responses to tumor cells and peptides in HLA-A24 positive hormone-refractory prostate cancer patients by peptide vaccination.

Background: To assess the safety and immune response of a peptide-based immunotherapy for patients with hormone-refractory prostate cancer, a phase I clinical trial was conducted.

Methods: This study first investigated whether cytotoxic T-lymphocyte (CTL) precursors reacting to peptide with vaccine candidates (14 peptides for HLA-A24 positive patients) were detectable in the pre-vaccination peripheral blood mononuclear cells (PBMCs) of ten patients with hormone-refractory prostate cancer. Patients were then vaccinated subcutaneously with only those peptides to which pre-vaccination PBMCs reacted (CTL precursor-oriented peptide vaccine) for up to four kinds of peptides.