Inhibition of Interleukin-10 in the tumor microenvironment can restore mesothelin chimeric antigen receptor T cell activity in pancreatic cancer in vitro

Background. Pancreatic cancer cells are known to shield themselves from immunosurveillance by secreting immune inhibitory cytokines such as Interleukin-10. Using mesothelin, a differentiating antigen that is overexpressed in pancreatic cancer, we assessed the negative effect of the tumor microenvironment on chimeric antigen receptor T cell-based immunotherapy and its reversal via depletion of Interleukin-10. Methods. T cells cultured in pancreatic cancer-cell-conditioned medium were transduced with lentiviruses encoding mesothelin-chimeric antigen receptor in the presence or absence of anti-Interleukin-10-blocking antibody. Results. Coculture supernatants of conditioned medium displayed significant inhibition of interferon gamma and granzyme B secretion, both of which are crucial for induction of target cell cytotoxicity. In contrast, this inhibition was restored toward baseline when conditioned medium was Interleukin-10-depleted (p <.05 for both interferon gamma and granzyme B). In addition, we observed a significant decrease in mesothelinchimeric antigen receptor T cell-induced cytotoxicity of BxPC-3 target cells in the presence of conditioned medium. Furthermore, we observed a partial blunting of this inhibition when Interleukin-10 was depleted from the conditioned medium. Conclusion. Substantial reversal of tumor-derived immunosuppression may be achieved by blocking Interleukin-10 in the local microenvironment, allowing for more effective cytotoxicity of mesothelin-engrafted chimeric antigen receptor T cells and enhancing the potential for clinical application. (C) 2017 Elsevier Inc. All rights reserved.