Clinical trials of immunotherapy for advanced prostate cancer

There is a lack of effective therapeutic regimens for advanced hormone-refractory prostate cancer (HRPC). Recent combination regimens of chemotherapy have improved management of HRPC. Neither systemic chemotherapy nor radiation regimens have significantly improved survival. Conventional systemic cytokine therapy has had limited efficacy in the treatment of advanced prostate cancer patients and its toxicity is severe. Combinations of multiple biological response modifiers for treatment of this disease also have limited efficacy. Results from phase II trials have shown that the combination of interferon-alpha and interleukin-2 therapy and the infusion of dendritic cells primed with peptides of prostate specific membrane antigen are promising. The former showed 31% response using the National Prostatic Cancer Project criteria, and the latter showed 27% of objective partial response with a reduction of >50% prostate specific antigen level. The toxicity of these two regimens was tolerated by patients. New approaches with tumor vaccines in conjunction with cytokine gene therapy have also been investigated. The clinical responses of these trials have been limited but promising. Immunotherapy may become an effective modality of prostate cancer treatment in the future.