Immunotherapy of Patients With Hormone-Refractory Prostate Carcinoma Pre-Treated With Interferon-Gamma and Vaccinated With Autologous PSA-Peptide Loaded Dendritic Cells--A Pilot Study

PURPOSE: We conducted a pilot trial to assess the feasibility and tolerability of a prime/boost vaccine strategy using interferon-gamma (IFN-γ) and autologous dendritic cells (DCs) pulsed with HLA-A2-specific prostate-specific antigen (PSA) peptides (PSA-1 [141-150]; PSA-2 [146-156]; PSA-3 [154-163]) for the treatment of 12 patients with hormone refractory prostate carcinoma. PATIENTS AND METHODS: All patients were vaccinated four times with intracutaneously injected PSA-peptide loaded DCs after subcutaneous administration of IFN-γ 2 hr before DC administration (50 μg/m² body surface). Objectives were safety, clinical benefit, clinical and biochemical response, quality of life, and immunological parameters. RESULTS: The vaccination was well tolerated without any vaccination-associated adverse events. One partial and one mixed responder were identified, four patients showed stable diseases. Two patients had a decrease and four a slow-down velocity slope in the PSA serum level. All responders showed a positive DTH-response, but only two a slight increase in PSA-peptide specific T-lymphocytes. CONCLUSION: The immunotherapy with IFN-γ and PSA-peptide loaded DCs was feasible and well tolerated. The observed responses imply a potential antitumor activity