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Tumor-targeted delivery of childhood vaccine recall antigens by attenuated Listeria reduces pancreatic cancer

Selvanesan, B. C.; Chandra, D.; Quispe-Tintaya, W.; Jahangir, A.; Patel, A.; Meena, K.; Alberto Alves Da Silva, R.; Li, J.; Siddiqui, S.; 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.

2019-12-19 immunology
10.1101/600106 bioRxiv
Show 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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