Abstract 5111: VentX-modulated tumor associated macrophages revert immune suppression in tumor microenvironment and promote efficacy of gemcitabine against pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is a lethal malignancy with median survival of less than one year and overall 5-year survival less than 5%. Gemcitabine has been the cornerstone in PDA treatment, yet its efficacy remains limited. Over the past decades, extensive investigations suggested a role of tumor microenvironment (TME) in rendering PDA resistance to gemcitabine, however, its underlying mechanism remained largely unknown. Cellular profiling has revealed the macrophages as a major immune cell component of PDA-TME. Our recent study showed that the expression of the homeobox protein VentX, a master regulator of macrophage plasticity, is significantly down-regulated in tumor associated macrophages (TAMs) of PDA. We demonstrated that restoration of VentX expression in PDA-TAMs polarizes the TAMs from a pro-tumor M2-like phenotype to an anti-tumor M1-like phenotype. We showed further that VentX-regulated-TAMs (VentX-TAMs) revert immune suppression of PDA-TME by inhibiting CD4 Treg differentiation and by promoting CD8 proliferation and activation. Using a newly developed tumor immune microenvironment-enabling model system (TIME-EMS), we showed that VentX-TAMs drastically promote efficacy of gemcitabine against PDA for about 4-fold but not cytotoxicity on normal pancreatic tissue. As such, our data suggested a function of VentX-TAMs to promote chemosensitivity of gemcitabine and to improve PDA prognosis. Citation Format: Joanna Le, Hong Gao, Yi Le, William Richards, Scott Radig, Ronald Bleday, Thomas Clancy, Zhenglun Zhu. VentX-modulated tumor associated macrophages revert immune suppression in tumor microenvironment and promote efficacy of gemcitabine against pancreatic cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5111.