Evaluation of Prostatic Acid Phosphatase (PAP) as a Candidate Antigen for the Development of Cancer Vaccines for Prostate Cancer

Abstract : The goal of this proposal is to evaluate prostatic acid phosphatase (PAP), a prostate tissue-specific protein, as a candidate tumor antigen for a prostate cancer vaccine. PAP is a well-defined protein, whose expression is limited to normal and malignant prostate tissue. In addition, data presented suggests that some patients with prostate cancer have a pre-existent immune response to PAP, suggesting that immune tolerance to this "self' protein can be circumvented. Studies described here will evaluate the immune response to PAP in patients with various stages of prostate cancer, characterize the T helper subset active in endogenous PAP-specific immunity, and test whether PAP-specific CTL derived from individual patients can lyse prostate tumor cells. The results of investigations described in this proposal will lead to a human phase I clinical vaccine trial targeting PAP in patients with prostate cancer. The specific aims of the current proposal are: (1) to determine whether patients with prostate cancer have a pre-existing CD4+ T cell immunity to PAP, and (2) to determine whether patients with prostate cancer have a pre-existing CD8+ T cell response to PAP and whether PAP-specific CTL derived from individual patients can lyse prostate tumor cells.