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

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Abstract
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. Prostate 67: 500–508, 2007.