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bioRxiv · 10.1101/600106

A new immunotherapeutic concept for pancreatic cancer using childhood vaccine recall antigens and Listeria

Abstract

Pancreatic ductal adenocarcinoma is highly metastatic, poorly immunogenic, and immune suppression prevents T cell activation in the tumor microenvironment. We developed a microbial-based immunotherapeutic concept for selective delivery of a highly immunogenic tetanus toxoid protein (TT856-1313), into tumor cells by attenuated Listeria monocytogenes, and reactivation of pre-existing TT-specific memory T cells (generated during childhood) to kill infected tumor cells. Thus, TT here functions as an alternative for neoantigens. Treatment of KPC mice with Listeria-TT resulted in TT accumulation in tumors and inside tumor cells, and attraction of predominantly TT-specific memory CD4 T cells. Moreover, gemcitabine (GEM) combined with Listeria-TT significantly improved the migration of CD4 T cells into tumors and the production of perforin and granzyme B, turning cold tumors into immunological hot tumors. In vivo depletion of T cells in Listeria-TT+GEM-treated mice demonstrated CD4 T cell-mediated eradication of tumors and metastases (Mann-Whitney p<0.05). In addition, peritumoral lymph node like structures (LNS) were observed in close contact with the pancreatic tumors displaying CD4 T cells and CD8 T cells of KPC mice treated with Listeria-TT or Listeria-TT+GEM. The production of perforin and granzyme B was observed in LNS of KPC mice that received Listeria-TT+GEM. This combination not only reduced tumor burden (80%) and metastases (87%) significantly (p<0.05, Mann-Whitney), but also improved the survival time of KPC mice with advanced pancreatic cancer substantially (Mantel-Cox p<0.0001). Our results unveil new mechanisms of Listeria and GEM improving immunotherapy for PDAC.

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BibTeXRIS

Selvanesan, B. C., Chandra, D., Quispe-Tintaya, W., Jahangir, A., Patel, A., Meena, K., Alberto Alves Da Silva, R., Libutti, S. K., Yuan, Z., Beck, A., Tesfa, L., Koba, W., Chuy, J., McAuliffe, J. C., Jafari, R., Entenberg, D., Wang, Y., Condeelis, J., Gravekamp, C.. 2019-04-05. A new immunotherapeutic concept for pancreatic cancer using childhood vaccine recall antigens and Listeria. https://doi.org/10.1101/600106

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