Prostate cancer is a leading cause of cancer-related deaths of men in the U.S., and in the past year, over 30,000 men died from this disease. While localized prostate cancer is highly treatable by surgical resection and radiation, cancer that has metastasized remains incurable. Alternatively activated macrophages, also known as M2-macrophages, primarily scavenge debris and in the process, promote angiogenesis and wound repair. M2-macrophages are phenotypically similar to M2 tumor-associated macrophages (M2-TAMs) have been reported to associate with solid tumors such as prostate cancer to facilitate epithelial to mesenchymal transition (EMT), tumor invasiveness, metastasis, and resistance to therapy. As an invasive species within the tumor microenvironment, this makes M2-TAMs an ideal therapeutic target in prostate cancer. The purpose of this project is to develop novel therapeutics that will directly target M2-TAMs for destruction and subsequently attenuate prostate tumor growth, progression and metastasis. The central hypothesis of this study is to determine if targeting of M2-TAMs using specific surface antigens will be an effective therapy for lethal prostate cancer and potentially, other cancers. Our study elucidated M2-Macrophage biology including creating homogenous populations of both M1 and M2 macrophages using a new strategy as to allow for identification of novel surface antigen markers. We then assessed novel markers of macrophage populations and assessed whether these surface antigens that are expressed on M2-macrophages are also expressed in human prostate cancers indicative of myeloid infiltration. Validation studies using metastatic prostate cancer tissues from rapid autopsies and surgical specimens supplied by the Department of Urology at Johns Hopkins University School of Medicine were also be performed. Complementary studies will be executed to target these markers for anti-tumor cell efficacy using these relevant model systems. By identifying and targeting specific markers on M2-TAMs, we predict that this targeting will provide a better prognosis for patients who have been diagnosed with lethal prostate cancer.

Citation Format: Jelani C. Zarif, James R. Hernandez, Kenneth J. Pienta. Targeting M2-tumor associated macrophages (M2-TAMs) in prostate cancer. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr B34.