The role of immunotherapy in prostate cancer: an overview of current approaches in development

Abstract

Ongoing clinical trials provide promise for the introduction of immunotherapy into the armamentarium against prostate cancer, but the precise role for immunotherapy remains to be determined. Combinations of immunotherapies may be needed to improve the response rates and the duration of response. Investigators have begun to examine the effect of immunotherapy in combination with other standard treatment, including as an adjuvant to chemotherapy or radiotherapy and as a neoadjuvant agent before prostatectomy. Although many studies examine efficacy in men with metastatic hormone-refractory prostate cancer, there is some evidence for improved responses at earlier stages of disease: the ability of the tumor to evade the immune system may be lessened with lower tumor burden, or the immune system may already be weakened in men with later stages of disease.

Keywords: Immunotherapy; Prostate cancer; Vaccine.

Figure 1

Schematic representation of the antitumor response and its modification by immunotherapy. CD4 and CD8 T cells are the cornerstone of this response, which is affected by tumor cell and dendritic cell antigen presentation. T cells in turn modulate some of the other host responses. Please refer to the text for further details. Reproduced with permission from Kiessling A et al, “Advances in specific immunotherapy for prostate cancer,” Eur Urol. 2008;53:694–708.

Figure 2

(A)Progression-free survival and (B) overall survival in hormone-refractory prostate cancer patients receiving high-dose versus low-dose GVAX prostate cancer vaccine. Reproduced with permission from Small EJ et al.

Figure 3

Overall survival improvement in phase III trial of sipuleucel-T. 95% CI, 95% confidence interval; HR, hazard ratio. Reproduced with permission from Small EJ et al.