Phase I/II Study of Vaccination With Antigen Loaded Dendritic Cells (DCs) in Hormone-Refractory Prostate Cancer

Dendritic cell (DC)-based immunotherapy is a promising approach to augment tumor antigen-specific T cell responses in cancer patients. However, tumor escape with down-regulation or complete loss of target antigens may limit the susceptibility of tumor cells to the immune attack. Concomitant generation of T cell responses against several immunodominant antigens may circumvent this potential drawback. In this phase I/II clinical trial, the investigators determined the immunostimulatory capacity of autologous DC pulsed with multiple T cell epitopes derived from four different prostate-specific antigens in patients with advanced hormone-refractory prostate cancer. Autologous DC of HLA-A\*0201-positive patients are loaded with antigenic peptides derived from prostate stem cell antigen, prostatic acid phosphatase, prostate-specific membrane antigen, and prostate-specific antigen. A strict quality control concerning the expression of surface markers and the migratory capacity of the DC secured optimal stimulatory capacity. DC were applied intradermally six times at biweekly intervals followed by monthly booster injections. Tolerability and PSA response will be investigated. Antigen-specific immune responses will be quantified.