Therapeutic vaccines for prostate cancer: what have we learned?

Abstract

Several characteristics of prostate cancer make it an attractive target for immunotherapy. The majority of tumors are relatively indolent, allowing for sufficient time to generate an immune response prior to disease progression. In addition, given the relatively few cytotoxic therapies of proven benefit, a large number of patients with advanced prostate cancer have had limited or no prior chemotherapy that can decrease the ability to mount an immune response. In recent years, numerous preclinical and clinical studies have investigated a variety of approaches to prostate cancer immunotherapy, including the use of vaccines consisting of whole tumor cells, antigen-presenting cells (APCs) and poxvirus-based vaccines. These trials are not only providing initial evidence of clinical efficacy, they are highlighting the importance of end points and patient selection in clinical trial design. This editorial reviews a few promising vaccines for prostate cancer and how clinical trials of these agents alone inform us about immunotherapy clinical trial design for metastatic castrate-resistant prostate cancer (CRPC).