Immunotherapy Improved By Utilizing Cellular Components Of Chemotherapy-Induced Tumor Cells

The development of immunotherapies has shifted the traditional cancer treatment paradigm.Among them,immune checkpoint blockade therapy has shown promising clinical efficacy in many advanced tumors.However,the great majority of cancer patients do not benefit from it.Fortunately,many studies have shown that cancer immunotherapy can be boosted by chemotherapy synergistically.The reason is that tumor cells treated with certain chemotherapeutic drugs can be induced to undergo immunogenic cell death,thereby exposing or releasing damage-related molecular patterns and tumor antigens.Therefore,combining with chemotherapy has become a popular strategy in many recent active clinical trials to improve immunotherapy.However,undesired side effects of chemotherapeutic drugs can to some extent weaken the synergistic effects of chemotherapy and immunotherapy.Therefore,we proposed to simulate systemic chemotherapy in vitro.This strategy can not only preserve chemotherapy-driven antitumor immune responses,but also avoid chemotherapy-mediated cytotoxicity.The main contents of this dissertation are as follows:(1)We decorated red blood cells(RBCs)with tumor proteins via the EDC/NHSmediated coupling reaction to prepare red blood cell based-vaccines(RBC-vaccines).Here,proteins derived from CT-26 cells treated with irinotecan were known as chemotherapy-induced tumor proteins(cTPs),but proteins acquired by repeatedly freezing and thawing parental CT-26 cells were referred to as nonchemotherapy induced tumor proteins(nTPs).The basis for this design is that RBCs can be selectively removed by phagocytes,which aids in the uptake of soluble tumor antigens.We discovered that RBC-vaccines administered subcutaneously could be mostly phagocytosed by dendritic cells.Compared with RBC-nTPs(RBCs modified with nTPs),RBC-cTPs(RBCs modified with cTPs)could promote more dendritic cell maturation.Subsequently,in the CT-26 colon cancer model,we found that the combination of RBC-cTPs and PD-1 inhibitor significantly inhibited tumor growth and prolonged the life span of the tumorbearing mice,and even cured them.Further mechanism analysis showed that RBCcTPs enhanced cancer immunotherapy by encouraging more T lymphocytes to infiltrate into tumor microenvironment than RBC-nTPs.In addition,the combination of RBCcTPs and PD-1 inhibitors could induce a long-term antitumor response.However,the antitumor immune memory could be lost following the depletion of CD8+T cells.(2)We prepared tumor RNA nanoparticles(RNA-NPs),in which tumor RNA was mixed with protamine to form complexes through electrostatic interactions.Here,RNA directly acquired from CT-26 cells was referred to as nonchemotherapy induced tumor RNA(N-RNA),and RNA extracted from chemotherapy-induced tumor cells was known as chemotherapy-induced tumor RNA(C-RNA).The maturation of dendritic cells was shown to be more effectively induced by subcutaneous injection of C-RNA nanoparticles(C-RNA-NPs)than N-RNA nanoparticles(N-RNA-NPs).And then,the RNA-NPs had no observable toxicity in major organs in in vivo studies.Subsequently,we discovered that the combination of C-RNA-NPs and PD-1 inhibitors significantly slowed tumor growth and increased survival time in the CT-26 colon cancer model.Further mechanistic analysis revealed that C-RNA-NPs could observably improve the immune checkpoint blockade therapy by boosting the distribution of T cells in the tumor microenvironment.In summary,the two approaches we proposed showed promising potential for enhancing immunotherapy.Finally,we hope to provide some ideas for improving cancer immunotherapy in the future.