Abstract 519: Identification of a novel target for antibody therapy of breast cancer

Identification of breast cancer-specific antigens may promote development of safe and successful immunotherapy of breast cancer. Caprin-1 has been known to be an intracellular protein related to cell proliferation as a function, but it has not been reported to be a target for the treatment of cancer. Here we report that this molecule is a novel breast cancer antigen which can be targeted for antibody therapy. Caprin-1 is highly expressed in at least 70% of breast cancers based on the results of immunohistochemical staining of human several breast cancer tissues, but hardly expressed in human normal tissues. Importantly, a part of this molecule is highly expressed in extracellular region of many breast cancer cells. A mouse monoclonal antibody raised against the extracellular domain of Caprin-1 showed anti-tumor effects in all tumor-bearing mouse models in which various cancer cells expressing Caprin-1 were implanted. The monoclonal antibody induced complete regression in one of the tumor-bearing models. Humanized antibody has been prepared and preclinical studies are currently underway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 519. doi:1538-7445.AM2012-519