Abstract 1275: Chemotactic factors underlying tumor infiltration by immunocompetent cells in colorectal cancer

Abstract Colorectal cancer (CRC) is a leading cause of cancer related death. Several studies have convincingly showed that CRC infiltration by immunocompetent cells and, in particular, cytotoxic CD8+ T cells, IFN-γ-producing cells, Foxp3+ regulatory T cells and CD16+ MPO+ neutrophils, is significantly associated with prolonged patient survival. However, the factors driving these cell populations into the tumor site remain to be elucidated. We are investigating the chemokine/chemokine receptor network promoting CRC infiltration by immune cells associated to favorable prognosis. We have analysed the expression of a panel of genes encoding for 39 chemokines and for 7 markers identifying specific immune cell types in 58 freshly excised specimens of CRC and corresponding control colonic tissues. In parallel, chemokine receptor profiles on clinically relevant immunocompetent cell populations have been characterized by flow cytometry. Our results suggest that tumor infiltration by immunocompetent cells associated to favorable prognosis is linked to the expression of three main chemokine patterns: 1) CCL3, CCL5, CXCL9, and CXCL10 capable of recruiting cytotoxic CD8+ and IFN-γ producing T cells; 2) CCL22 and CXCL12 attracting Foxp3+ regulatory T cells; 3) CXCL2, CXCL5 and CXCL8 inducing migration of CD16+ MPO+ neutrophils. We have started to investigate the chemokine sources. CRC cells purified from tumor specimens were found to express chemokines potentially recruiting T and myeloid cells, including CCL3, CCL5, CXCL9, CXCL10, CXCL12, and CXCL2, CXCL5, CXCL8. The stimuli driving chemokine expression by tumor cells remain however to be clarified and are currently under investigation. Citation Format: Eleonora Cremonesi, Francesca Amicarella, Elisabetta Padovan, Manuele G. Muraro, Valentina Mele, Paul Zajac, Christian Hirt, Raoul Droeser, Daniel Oertli, Markus Zuber, Michel Adamina, Raffaele Rosso, Jesus G. Garzon, Lubor Borsig, Giulio C. Spagnoli, Giandomenica Iezzi. Chemotactic factors underlying tumor infiltration by immunocompetent cells in colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1275. doi:10.1158/1538-7445.AM2015-1275