Immunotherapy for pancreatic cancer
Abstract: Patients with pancreatic cancer have a short life expectancy, and only 20% of the patients diagnosed with pancreatic cancer can undergo surgery. Chemotherapy does not work well: Gemcitabine is the standard regimen with a 5-year survival rate of 1%–4% and a median survival time of 4-6 months; FOLFIRINOX chemotherapy regimen using four drugs was found to be more effective (median survival 11 months), but with substantial side effects. In this thesis, we aim to find new ways to treat pancreatic cancer by immunotherapy. In Paper I, we established a new protocol to expand tumor-infiltrating lymphocytes (TIL) from pancreatic cancer tumor tissues. Those T cells were able to recognize and kill autologous tumor cells, and produced Th1 signature cytokines, particularly IFN-γ. In Paper II, we identified the individual mutations in pancreatic cancers by whole-genome sequencing. We found that T cells from the tumor or peripheral blood could recognize the mutations, such as mutated K-ras. One CD4+ TIL clone recognized a novel (neo) epitope (GLLRYWRTERLF) derived from an aquaporin 1-like molecule (K7N7A8 protein product). Those T cells could be a source for T cell receptor (TCR) transfer to treat patients. In Paper III, we established tumor-infiltrating B lymphocyte (TIB) cell lines from patients with pancreatic cancer and patients with glioblastoma. We found that TIB produced antibodies that could recognize EBV and/or CMV peptides. Those peptides were also recognized by TILs. One CMV peptide (CEDVPSGKLFMH) showed to be recognized by TIB, TILs, peripheral T cells and serum antibodies from one same patient, PanTT32. Antigen-specific B cell receptors (BCR) from TIBs could be a source for the construction of chimeric antigen receptor (CAR) T cells. In Paper IV, we cultured peripheral blood cells from patients with pancreatic cancer with mesothelin peptides. A survival benefit was linked to IFN-γ production to peptides corresponding to the mature mesothelin and to targeted recognition of the mesothelin601-615 epitope (MQEALSGTPCLLGPG; p=0.006) in the presence of IL-21. The peptide mesothelin601-615 could therefore be a candidate for pancreatic cancer vaccines.
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