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-gamma) 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-gamma 2 hr before DC administration (50 microg/m(2) 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-gamma and PSA-peptide loaded DCs was feasible and well tolerated. The observed responses imply a potential antitumor activity.