Active immunotherapy is dependent on the ability of the immune system to recognize and respond to
tumors. Despite overwhelming evidence to support a cell-mediated immune response to
prostate cancer, it is insufficient to eradicate the disease. This is likely due to a high level of suppression at the
tumor site from a variety of sources, including immunosuppressive cells. Immune cells entering the tumor microenvironment may be inhibited directly by the
tumor, stromal cells or other immune cells that have been induced to adopt a suppressive phenotype. The resurgence of interest in
immunotherapy following the approval of
sipuleucel-T and
ipilimumab by the Food and Drug Administration has brought about new strategies for overcoming
tumor-mediated suppression and bolstering anti-
tumor responses. Improved understanding of the immune response to
prostate cancer can lead to new combination
therapies, such as the use of
vaccine with small molecule and checkpoint inhibitors or other
immunotherapies.