Preparation And Antitumor Study Of Bortezomib-Based Nanomedicine With Immunomodulatory Properties

Although nanomedicine has been widely used in tumor therapy,the clinical efficacy of nanomedicine developed based on chemotherapeutic drugs has not been significantly improved,and the overall survival rate of patients also fails to be elevated greatly.This could be presumably attributed to the abnormal microenvironment of the tumor,and the immunosuppressive tumor microenvironment also greatly limits the activation and infiltration of immune cells,thereby reducing the treatment efficacy of nanomedicine.Therefore,the design of nanomedicine with tumor immune microenvironment modulation which combines chemotherapy and immunotherapy can not only overcome the limited efficacy of the single treatment but also effectively reduce the side effects,which is promising in clinical applications.Bortezomib(BTZ)is the first proteasome inhibitor approved by the FDA for the clinical treatment of multiple myeloma,but its application in the treatment of solid tumors is limited due to its poor stability and high toxicity in vivo.This thesis designed two bortezomib-based nanomedicine with tumor immunomodulatory properties in order to increase the tumor accumulation of BTZ and enhance the tumor infiltration of immune cells,thereby reducing the side effects of chemotherapeutic drugs as well as enhancing the tumor treatment efficacy of bortezomib-based nanomedicine.The tortuous and heterogeneous tumor vascular system constitutes the main obstacles to nanomedicine delivery.Hence,a pH-responsive bortezomib nanomedicine(PHDZ/BTZ)based on hydralazine(HDZ)was designed in the first part of this thesis.Tumor blood vessels were dilated due to the pH-responsive release of HDZ,thereby enhancing the tumor accumulation of BTZ,modulating the tumor immune microenvironment,and improving the therapeutic efficacy of bortezomib nanomedicine.The amphiphilic polymer PHDZ realized the efficient loading of BTZ through the Lewis acid-base coordination between the amino group and the boronic acid group(the drug loading rate was 18.7%),and the obtained nanomedicine(PHDZ/BTZ)had a particle size of about 138.4 nm with a surface potential of-2.2 mV,showing good stability in serum and suitable for applications in vivo.Since PHDZ contained pHresponsive hydrazone bonds,the hydrazone bonds would break and cause the massive release of HDZ in the acidic microenvironment of tumors,thereby promoting tumor vasodilation,opening up more drug delivery windows,and significantly improving the delivery efficiency of BTZ.Moreover,the improved BTZ-based tumor therapy under the tumor vasodilation effect promoted DC cell maturation and CD8+T cell infiltration into tumor tissue,which effectively remodeled the tumor immunosuppressive microenvironment and further improved the therapeutic efficacy of BTZ-based nanomedicine.With its high drug-loading capacity and the immunomodulatory properties of the tumor microenvironment,PHDZ/BTZ effectively enhanced the tumor treatment efficacy of BTZ and significantly reduced the toxic effects,and had great clinical transformation potential.The difficult-to-activate tumor immunosuppressive microenvironment is also an important factor affecting the efficacy of nanomedicine.In the second part of this thesis,a pH-responsive bortezomib nanomedicine(PAG/BTZ)based on aminoguanidine(AG)was designed.By the pH-responsive release of BTZ and AG,PAG/BTZ not only killed tumor cells,but also improved the presentation and processing of antigens by antigenpresenting cells,thereby activating the tumor immune microenvironment,and improving the therapeutic efficacy of bortezomib-based nanomedicines.The guanidinemodified amphiphilic polymer PAG exhibited efficient loading of BTZ through the hydrogen bond and electrostatic adsorption between the guanidine group and the boronic acid group(the drug loading rate was 22.1%),and the obtained nanomedicine(PAG/BTZ)was with a particle size of about 71.4 nm and a surface potential of 19.4 mV.The results of in vitro and in vivo experiments in mice showed that PAG/BTZ significantly reduced the toxicity of BTZ,improved the in vivo pharmacokinetics of BTZ,and prolonged the in vivo circulation time of BTZ.In addition,PAG/BTZ promoted the uptake of model antigens by antigen-presenting cells and the maturation of DC cells,induced the secretion of pro-inflammatory cytokines,and promoted the infiltration of cytotoxic T cells in tumor tissues,thereby activating the immune response.In the subcutaneous breast cancer tumor model,PAG/BTZ showed significantly enhanced chemotherapeutic effects compared with BTZ,produced stronger anti-tumor immune responses,reduced side effects,and had good biosafety.