The Function And Mechnism Research Of Treatment Of Pancreatic Cancer With Enhanced CD8+T Cell Fuction In Combination With Chemoradiotherapy

The First Part: The study of function of the new co-stimulatory pathway B7H5/CD28 H in pancreatic cancer and its treatment effect with gemcitabineBackground Pancreatic ductal adenocarcinoma is one of the most deadly desease due to its delayed diagnosis,low surgical excision rate and limited response to current treatments.Resently,durable responses to immunotherapy have been reported in a lot of cancers.These responses were often associated with significant infiltration of cytotoxic T lymphocytes(CTL)into the tumor tissue.In pancreatic cancer,the unique tumor microenvironment help the tumor cells escape from immune attack and make activated T cells exhausted.B7H5 and its receptor CD28 H have been identified as the second signaling transduction molecules of T lymphocytes.There is lack of detailed studies of B7H5 expression in pancreatic adenocarcinoma,especially its prognostic value.Aim The aim of this study is to assess the biological function of B7-H5/CD28 H pathway both in vitro and in vivo,and the expression patterns and clinical significance of this pathway in patients with pancreatic cancer.Also,To evaluate the effects of Tazarotene and synergies with gemcitabine in the treatment of pancreatic cancer.Methods and Materials In vitro experiments,CFSE was used to detecte T-cell proliferation and Elisa was used to detect cytokine secretion,like IFN-? and TNF-a after coculture of T cells and tumor cells with different expression levels of B7H5.In vivo,we constructed a NOG xenograft model of pancreatic cancer with different B7H5 expression levels,and T cells were injected by tail vein to study its therapeutic effect.Surgical tumor specimens were collected for immunohistochemical staining and flow cytometry to evaluate expression of B7H5/CD28 H.The relationship between the expression of B7H5/CD28 H and the prognosis was explored.Results B7H5 can stimulate the proliferation of CD8 cells and elevate release of TNF-a,IFN-? and other cytokines.Of the 136 PDAC tumor tissues,93(68.38%)were strong,and patients with strong B7H5 expression had significantly longer overall survival than those with weak expression.B7H5 is an independent prognostic factor affecting the overall survival of pancreatic cancer.The expression of CD28 H on T lymphocytes in tumor microenvironment of pancreatic cancer was lower than that in peripheral circulation.Tazarotene can up-regulate B7H5 and in combination with Gemcitabine has a good therapeutic effect on pancreatic cancer.Conclusion B7H5/CD28 H is a co-stimulatory signal pathway of T cells,and expression of B7-H5 is associated with improved disease prognosis in patients with pancreatic cancer.Tazarotene in combination with Gemcitabine has a good therapeutic effect on pancreatic cancer due to its effect of enhancing T cell function by up-regulation of B7H5.The Second Part: The study of effect and mechanism of Combo-i targeting MDSCs/Tregs in combination with GVAX and a PD-1 in the treatment of pancreatic cancerBackground The current therapies,including surgical resection,radiotherapy and chemotherapy,have failed to improve the survival of pancreatic cancer patients.The traditional treatment in combination with immunotherapy is the new hope.However,immunotherapy is not effective in pancreatic cancer,which may be due to the lack of T cell infiltration in the microenvironment of pancreatic cancer,but the abundance of suppressive immune cells.GVAX can increase T cell infiltration into tumor but also induce PDL1 expression.Combo-i is a new-designed drug that target immunosuppressive cells.Aim The effects of Combo-i targeting immunosuppressive cells in combination with radiotherapy,GVAX and a PD1 in the treatment of pancreatic cancer were evaluated by in vivo tumor bearing mice models.Flow cytometry was used to analyze the effect of combined therapy on immune microenvironment of pancreatic cancer.Methods and Materials In vivo experiment,mice liver metastasis model and orthotopic model were established.Different treatment combinations of Combo-i,radiotherapy,GVAX and PD1 antibody were given to evaluate whether Combo-i targeting immunosuppressive cells combined with other treatment methods had synergistic treatment effects on pancreatic cancer.In vitro,the effects of Combo-i combined with other therapies on macrophages,MDSCs,Treg cells,effective T cells and memory T cells in pancreatic cancer were detected by flow cytometry.CD11 b + cells in each treatment group were isolated and subsequently sequenced.Results ELISA result showed that Combo-i combined with GVAX and a PD-1 could promote IFN? secretion of T cells.In the mouse model,GVAX has no additional antitumor effect when added to Combo-i+a PD-1+RT.Combo-i+a PD-1+RT is better than other treatment combinations.Flow cytometry showed that Combo-i+a PD-1+RT could reduce the infiltration of macrophages,MDSCs and Treg cells and increase the infiltration of T cells,effective T cells and memory T cells.Conclusion Targeted inhibitor Combo-i can enhance the therapeutic effect of RT + a PD-1 on pancreatic cancer.Its therapeutic effect on pancreatic cancer is attributed to its ability to reduce the infiltration of macrophages,MDSCs,Treg cells and other immunosuppressive cells in the immune microenvironment,while increasing the infiltration of T cells,effective T cells and memory T cells.