Abstract 1406: Analysis of immune responses as a consequence of androgen deprivation therapy in patients with biochemical progression of prostate cancer

We evaluated the immune responses in 28 patients enrolled in a phase II trial at the National Cancer Institute (NCI). The aim was to investigate the effects of 3 months of androgen deprivation therapy (ADT) with goserelin on the immune responses in patients with biochemical progression of prostate cancer following local definitive therapy. PBMC and sera were collected before treatment and after 3 months. We performed flow cytometry to evaluate the frequencies of subsets of CD4+ and CD8+ T-cells, regulatory T-cells (CD4+ CD25hi CD127− FoxP3+), MDSCs and CD4 and CD8 recent thymic emigrants. CD4 T-cell proliferation and NK-cell lytic activity were evaluated. Serum samples were analyzed for cytokines, sCD27 and sCD40L. The baseline characteristics were: median age 64 years, testosterone 361 ng/dl, PSA 2.2 ng/ml, PSA-doubling time 7.0 months, and Gleason score 7. After 3 months of ADT we found no significant changes in NK-cell function or frequencies of NK subsets. CD4+ T-cell proliferation decreased slightly. The number of CD4+ effector memory T-cells decreased, but other CD4 subsets were unchanged. The frequencies of CD4 and CD8 recent thymic emigrants did not change. Regulatory T-cells (including the CTLA4+ subset), and the effector:Treg ratio did not change. In contrast, the frequency of granulocytic MDSC decreased (P