Light-controllable Charge-reversal Nanoparticles With Polyinosinic-polycytidylic Acid For Enhancing Immunotherapy Of Triple Negative Breast Cancer

Triple negative breast cancer(TNBC),a type of breast cancer characterized by negative expression of estrogen receptor(ER~-),progesterone receptor(PR~-)and HER2 receptor(HER2~-),which is of aggressive invasion and high metastasis,accounts for about 15%of breast cancer cases.In clinic,chemotherapy is still most frequently used approach to treat TNBC.However,due to drug resistance and adverse effects of chemotherapeutics,exploring new approaches to treat TNBC are still highly desirable to improve therapeutic benefits in patients.Cancer immunotherapy,as another vital clinical strategy for cancer treatment,is aimed to strengthen immune system to eliminate malignant cells,and has made great progress in the treatment of advanced TNBC tumors.Nucleic acid drugs,such as Poly(I:C),Cp G Oligodeoxynucleotides,m RNA vaccines and si RNA,are commonly used to enhance tumor immunogenicity in immunotherapy.However,they are easy to be filtered by glomerulus or rapidly decomposed by nuclease in plasma,which leads to poor accumulation in target sites.Meanwhile,due to its physicochemical properties,such as electronegativity and large molecular weight,nucleic acid drugs are hardly uptake by tumor cells.Non-virus drug delivery systems are of low immunogenicity,low production cost,good reproducibility and high safety,which is widely used in delivery of nucleic acid drugs.Cationic nanoparticles,one of the non-viral drug delivery systems,could load nucleic acid polymers via electrostatic interaction to enhance nucleic acid drug stability,improve drug distribution and uptake by target cells.However,the release of nucleic acid drugs was blocked by positive charged nanoparticles in cells,leading to degradation and reduced efficacy.Taking advantage of low p H,enzymes and hypoxia of the tumor microenvironment,as well as combining external stimuli such as near infrared and heat,stimulus-responsive drug delivery systems are designed to promote drug release.Herein,a light-controllable charge-reversal nanoparticle(LCCN)was designed in co-delivery of photosensitizer chlorin e6(Ce6)and TLR3 agonist Poly(I:C)to enhance photodynamic immunotherapy of TNBC.(Fmoc)-KCRGDK-phenylboronic acid(FK-PBA)was synthesized by the sulfydryl reaction and Ce6 was conjugated with hydrophilic polyethyleneimine(PEI)through amide condensation reaction.The nanoparticles are self-assembled by co-precipitation of 9-fluorenyl methoxycarbonyl FK-PBA with polyvinyl alcohol(PVA)and cationic PEI-Ce6,which enable to load anionic Poly(I:C).Phenylboronic ester groups between the FK-PBA and diols of PVA was reactive oxygen species(ROS)produced by Ce6 under near-infrared(NIR)irradiation and sequentially was induced to cleave in fast kinetics.Amino group of PEI was shielded by boric acid and phenol structure,which made a positive to negative charge-reversal of LCCN to promote the release of Poly(I:C).Moreover,the disulfide linkage of FK-PBA could be reduced in reduction microenvironment,triggering the further disassembly of LCCN.LCCN was investigated to increase the accumulation of nucleic acid drugs in tumor sites via enhanced permeation and retention(EPR)effect,promote maturation of dendritic cells(DCs),induce immunogenic cell death(ICD),activate antitumor immune responses and significantly inhibit the tumor growth in 4T1 tumor-bearing mouse model.Our study demonstrated that LCCN-Poly(I:C)could achieve light-controlled release of Poly(I:C),and improve the therapeutic effects on inhibiting the growth of TNBC tumor,showing promising potential for clinical transformation.