Functional Polymer-based Nanovaccines For Cancer Immunotherapy

Cancer immunotherapy has brought great hope to the fight against cancer in recent years.Different types of cancer immunotherapy strategies have been extensively studied or tested in clinic,alone or in combination with other conventional therapeutic strategies,such as chemotherapy or radiotherapy.Compared with passive immunotherapy such as monoclonal antibody treatment,vaccine is an active immune strategy,which can induce or amplify specific cellular and humoral immune responses against tumor,and induce long-term immune memory response,thereby reducing tumor recurrence.In order to activate and expand tumour-specific T cells,cytosolic delivery and cross-presentation of antigens by antigen-presenting cells via the major histocompatibility complex class I(MHC-I)antigen-presenting pathway are essential to trigger robust antitumour responses However,the clinical results showed that the uptake of vaccines by antigen-presenting cells were not large,leading to low efficiency of antigen cross-presentation,which limited the efficacy of vaccines in clinical treatment.Nanoparticles expecially some polymers could induce cross-presentation more directly following internalization via endosome/phagosome escape and direct delivery of antigen to the cytosol,where they can be processed by the normal MHC I loading pathways.Based on this,aiming at the problems of low uptake by APCs and low efficiency of antigen cross presentation,this doctoral dissertation designed and constructed a variety of nano vaccines to improve the immunogenicity of antigen,and carefully explored the mechanism of immune induction and the efficacy of combined treatment with immune checkpoint blockade therapy.The main research methods and conclusions of this thesis are as follows:Using guanidine benzoic acid(GBA)modified polyamide amine(PAMAM)dendrimer(DGBA)as the vaccine carrier,we successfully constructed a dendrimer based vaccine complex(DGBA-OVA-CpG),which was composed of three key components:DGBA,TLR9 agonist CpG and chicken ovalbumin(OVA)antigen.The nano composites effectively enhanced the delivery of OVA to cells and lysosome escape,and then achieved effective antigen cross presentation in APCs.The immunogenicity and antitumor immune response of the antigen were further enhanced by the introduction of CpG,a TLR9 agonist,as an adjuvant.Such a nano vaccine preparation by simply mixing all components could be less than 30 minutes.The DGBA-OVA-CpG nanovaccine could not only induce a good preventive effect on B 16-OVA melanoma(expressed OVA)in vivo,but also could be used as a therapeutic vaccine to effectively inhibit the growth of B 16-OVA melanoma and prolong the survival time of mice after combined with anti-PD-1 immune checkpoint inhibition.Fluorinated polymers have excellent self-assembly ability because of their high surface activity,and their hydrophobic and oil repellent properties make them have good biocompatibility,high cell uptake level and low cytotoxicity.The F-PEI/OVA nanovaccine with OVA as antigen was constructed by simply mixing the fluorinated polyethyleneimine(PEI)as vaccine carrier(F-PEI).Fluorinated PEI could enhance the uptake of OVA by APCs and lysosomal escape,and further could induce cross presentation of OVA.At the same time,F-PEI/OVA could induce the internalization mediated immune response by Toll like receptor 4(TLR4)to activate the maturation of DCs.In vitro and in vivo data show that the F-PEI/OVA nanovaccine could induce OVA-specific cellular immune response.At the same time,it was not only able to prevent B 16-OVA melanoma,but also effectively inhibit the growth of B 16-OVA melanoma as a therapeutic vaccine.Based on the research results above,we used F13-PEI to construct a kind of personalised F13-PEI/Membrane nanovaccine.More significantly,a mix of the fluoropolymer with cell membranes from resected autologous primary tumours synergizes with checkpoint-blockade therapy to inhibit post-surgical tumour recurrence and metastases in two subcutaneous tumour models and an orthotopic breast cancer tumour.Furthermore,in the orthotopic tumour model,we observed a strong immune-memory against tumour re-challenge.Our work offers a simple and general strategy for the preparation of personalised cancer vaccines to prevent post-operative cancer recurrence and metastasis.In summary,we constructed a variety of nano vaccines to effectively enhance the uptake of the vaccine by APCsand the antigen cross presentation.At the same time,aiming at the problem of tumor recurrence and metastasis after surgical resection,a personalised nano vaccine based on fluorinated polymer was developed by using tumor cell membrane as antigen.Due to the excellent therapeutic efficacy,it is possible for the clinical transformation of related strategies in the future.