Understanding the tumor-immune microenvironment in prostate cancer

Purpose of reviewThis review aims to highlight recent advances in prostate cancer tumor-immune microenvironment research and summarize the state-of-the-art knowledge of immune checkpoint inhibitors in prostate cancer.Recent findingsImmune checkpoint inhibitors are the cornerstone of modern immunotherapy which have shown encouraging results across a spectrum of cancers. However, only limited survival benefit has been seen in patients with prostate cancer. Prostate cancer progression and its response to immunotherapies are strongly influenced by the tumor-immune microenvironment, whose feature can be summarized as low amounts of tumor-specific antigens, low frequency of tumor-infiltrating lymphocytes and high frequency of tumor-associated macrophages. To improve the therapeutic effect of immunotherapies, in recent years, many strategies have been applied, of which the most promising ones include the combination of multiple immunotherapeutic agents, the combination of an immunotherapeutic agent with other modalities in parallel or in sequential, and the development of biomarkers to find a subgroup of patients who may benefit the most from immunotherapeutic agents.SummaryThe impact of immune content and specific immune cell types on prostate cancer biology is highly complex. Recent clinical trials have shed light on the optimal use of immunotherapies for prostate cancer.