Abstract 2902: Targeting the tight junction protein claudin-1 in colorectal cancer

Colorectal cancer (CRC) is one of the major causes of cancer-related deaths in the Western world. When localized, CRC is often curable by surgery, but the prognosis of patients with metastatic disease remains very poor. The current treatment of metastatic CRC (mCRC) relies on therapy combining chemotherapy and targeted therapies. However, relapses are observed in most cases due to the occurrence of drug resistance. Therefore, more therapeutic options are required particularly by identifying new molecular targets that can be reached by antibodies. We previously showed that Claudin-1 (CLDN1), a major constituent of tight junctions, is overexpressed at the membrane of CRC cells which makes it a good target for antibodies. Besides, CLDN1 is differentially expressed in the new CRC molecular subtypes. We have then developed a monoclonal antibody (mAb) against CLDN1, called 6F6, which targets the extracellular part of CLDN1. Results showed that the 6F6 mAb significantly decreased cell growth, survival, and migration in vitro as well as in vivo. Furthermore, we demonstrated the cytostatic effect of the 6F6 mAb through proliferation assays. We are now deciphering the role of CLDN1 on 3D spheroids, a model that reflects the physiopathology. Using immunofluorescence staining on frozen sections we are exploring the impact of CLDN1 on spheroids proliferation. We are also investigating on the distribution of tight junction proteins implicated on cell proliferation in the presence or absence of CLDN1. CLDN1 is a new promising therapeutic target in CRC, it is now interesting to elucidate its role in colorectal cancer cell proliferation. Keywords: Colorectal, Cancer, Claudin-1, monoclonal antibodies, spheroids, proliferation Citation Format: Sara Cherradi, Adeline Ayrolles-Torro, Nadia Vezzo-Vié, Eve Combes, Lucile Canterel-Thouennon, Fabien Gava, Valérie Lobjois, Bernard Ducommun, Celine Gongora, Maguy Del Rio. Targeting the tight junction protein claudin-1 in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2902.