Mannan-BAM, TLR ligands, and anti-CD40 immunotherapy in established murine pancreatic adenocarcinoma: understanding therapeutic potentials and limitations

Abstract

The aim of this RNDr. Thesis is focused on understanding therapeutic potentials and limitations of the antitumor MBTA immunotherapy which is based on synergy of TLR agonists, anti-CD40, and phagocytosis stimulating ligands anchored into the tumor cell membranes. In this study, immunotherapy was tested in murine pancreatic adenocarcinoma Panc02 model. Firstly, the short-term and long-term efficacy of MBTA therapy was tested using established subcutaneous Panc02 tumors two times larger than in previous study. Secondly, the work is devoted to better understanding of the adaptive immunity involvement focusing on CD4+ and CD8+ T lymphocytes during the therapy and their effect on tumor volume reduction, long-term survival and resistance against tumor rechallenge. Subsequently, the ability of immunological memory to cross over the blood-brain barrier confirming its potential applicability in metastatic brain tumors was examined. Moreover, the antigen specificity of the immunological memory was evaluated. Finally, the potential of MBTA therapy to cure metastatic disease, represented by bilateral Panc02 mouse model, was studied. In this case, the MBTA therapy manifested a lower therapeutic response. Therefore, it was combined with diverse therapeutic approaches, such as intratumoral application of anti-CTLA-4 antibody, heat-killed Listeria monocytogenes, chemoablation using EtOH, targeting the tumor microenvironment by hyaluronidase, simultaneous injections of MBTA therapy in primary and secondary distant tumors, and its combination with RT. Despite all these combinations, our results showed that only simultaneous application of MBTA therapy into both tumors has potential for the treatment of the bilateral Panc02.