Design Of Functionalized Peptide/Protein Nanoparticles And Their Application In Tumor Immunotherapy

With the development of molecular biology and immunology,tumor immunotherapy has become the most potential tumor therapy after surgery,chemotherapy,and radiotherapy.Although cancer immunotherapy has shown strong anti-tumor activity in the treatment of a variety of solid tumors,immunotherapy drugs given systemically are easy to cause serious toxic and side effects,and the heterogeneity of tumor also causes low objective response rate of immunotherapy.Immunotherapeutic drugs also have the problems of low bioavailability and low targeting specificity.In recent years,many studies have shown that nanotechnology can improve the deficiency of immunotherapeutic drugs,greatly improve the distribution of immunotherapeutic drugs in vivo,and avoid the toxic and side effects caused by systemic administration.Nanotechnology provides a new drug administration scheme for the further promotion of immunotherapeutic drugs in clinic.Peptide/protein-based nanoparticles have good biocompatibility and flexible modifiability,and play an important role in immunotherapy drug delivery.Starting from solving the problem of in vivo delivery of immunotherapeutic drugs,this paper has carried out relevant innovative research on the design of drug targeted delivery and improving the curative effect.The main contents are summarized as follows:To improve the enrichment of immune checkpoint blockade peptide at the tumor site,we synthesized an amphiphilic peptide which could sequentially response with tumor weekly acid and MMP2 according to the self-assembly principle of amphiphilic peptides.The hydrophilic end is the immune checkpoint blocked peptide DPPA-1,and the hydrophobic end is tumor microacid responsive small molecule thioisocyanate(DEAP)and MMP2 responsive peptide(PLGLAG).The indoleamine 2,3 dioxygenase(IDO)inhibitor NLG919 was encapsulated in the nanoparticles by intermolecular force.A tumor targeting immunotherapy agent-NLG919@DEAP-DPPA-1 was obtained.This drug can effectively improve the bioavailability of peptide drugs,and can significantly improve the efficacy when combined with NLG919,a small molecular inhibitor at the immune checkpoint.This work provides a dual targeted tumor immunotherapy strategy,which can effectively improve drug availability and efficacy by sequentially responding to tumor microenvironment microacids and MMP2 enzymes,and open a targeted therapy strategy for tumor immunotherapy.To improve the enrichment of immune checkpoint blockade small molecular drugs in the tumor site,we designed a prodrug through solid phase synthesis.NLG919 was coupled with a segment of polypeptide with esterase response(ester bond),acid response(ionizable histidine)and tumor targeting(RGD)to obtain self-assembled prodrug NLG-RGD.The prodrug can expose the esterase cleavage site in response to the acidic environment of lysosomes,and then release NLG919,which can effectively alleviate the tumor immunosuppressive microenvironment.The addition of αPD-L1 can further protect T cells,and finally achieve the purpose of killing tumor efficiently.This work enhances the anti-tumor immunity of immune checkpoint blocking antibody by developing an IDO targeted nano-inhibitor,which provides a strategy for the clinical use of IDO small molecule inhibitors.In the design of tumor vaccine,the full drainage of antigen to lymph nodes has always been a difficult problem.We used fusion expression technique to express two kinds of tumor antigen peptides with virus-like particles respectively.Using the performance of virus-like particles depolymerization and reassembly,we obtained a hybrid virus-like particle vaccine with double antigens.The vaccine can effectively stimulate innate immunity,promote DC maturation and antigen presentation,and achieve specific immune response to two tumor antigens,effectively kill tumor cells,and has a good therapeutic effect on subcutaneous tumor and lung metastasis model.This work can achieve personalized treatment by inserting different tumor antigens,solve the problem of tumor heterogeneity,and provide a new strategy for tumor vaccine antigen transport.