Dendritic cell-based immunotherapy of prostate cancer: Immune monitoring of a phase II clinical trial

We assessed both non- and peptide-specific immune responses in prostate can cer patients before and after immunotherapy with dendritic cells exogenousl y pulsed with the prostate-specific membrane antigen-derived peptides, PSM- P1 and PSM-P2 For all subjects, we observed that clinical responses were st rongly associated with two indicators of immunocompetence: skin test respon ses to recall antigens and cytokine secretion by T cells after nonspecific stimulation. In a subset of responders, we observed cytokine secretion or c ytotoxicity against the immunizing peptides or an immunodominant epitope fr om an influenza recall antigen. The clinical results support the use of mon itoring for overall immunocompetence to help determine why a patient has or has not responded to therapy. Moreover, it could be useful as an inclusion criterion to select those more likely to benefit from treatment.