The Combination Of Tumor Lysate Loaded Nanovaccine And ~DPPA-1 To Induce Antitumor Immunity And Block Immune Checkpoint For Cancer Immunotherapy

Objectives:Tumor can conduct a series of immunosuppressive mechanisms during the invasion,which is the main limitation for cancer immunotherapy.In order to induce potent anti-tumor immunity,we employed a lipid-enveloped zinc phosphate(LZnP)nanoparticle to deliver tumor lysates(TLS)and adjuvant(MPLA)to activate immune system.We also involved an immune checkpoint antagonist(~DPPA-1)to inhibit tumor immunosuppression by specifically blocking PD-1/PD-L1 pathway.The combination therapy can induce potent anti-tumor immune response,reduce the occurrence of tumor evasion and inhibit tumor growth.Methods:TLS was prepared by freeze-thaw cycles and analyzed by SDS-PAGE.The LZnP nanoparticles was prepared via the reverse micro-emulsion and film-hydration method.Then the physical/chemical characteristics and loading capability were analyzed by transmission electron microscope(TEM),fourier transform infrared spectroscopy(FTIR),dynamic light scattering(DLS)and BCA,respectively.The population of matured dendritic cells(DCs)and CD8~+and CD4~+T cells were analyzed by fluorescence activated cell sorting(FACS).And the production of related cytokines was evaluated by enzyme-linked immuno sorbent assay(ELISA)kit.In B16F10 tumor model,the anti-tumor efficiency of TLS loaded LZnP nanoparticles as well as the combination therapy with immune checkpoint antagonist were evaluated.Results:After freeze-thaw cycles,TLS remained majority of proteins from tumor,which provide more epitopes for immunotherapy.TLS loaded LZnP nanoparticles based vaccine possessed the uniform morphology and homogeneity,with the size around 30 nm.The loading capability was about 77%.LZnP nanoparticles based vaccine successfully induced maturation of bone marrow dendritic cells(BMDC)and enhanced the production of related cytokines.From the animal experiments,the LZnP nanoparticles based vaccine exhibited potent anti-tumor effect.The similar results were observed in the combination therapy of immune checkpoint therapy.Conclusions:TLS can serve as potent antigenic agent since it can provide more epitopes for T cell recognition and reduce the probability for tumor escaping from immune surveillance.By constructing LZnP nanoparticles based vaccine,TLS and adjuvant can be efficiently delivered to lymph node.This vaccine can promote the maturation of DCs and enhance antigen uptake and antigen presentation.By introducing immune checkpoint therapy to regular treatment,it can be regarded as a favorable option to exhibit synergistic effect with vaccine.The combination therapy successfully induced potent cytotoxicity T cells response and enhanced the antitumor effect.