Responsive Polymersome Nanofactories For Enhanced Enzyme Prodrug Chemo-Immunotherapy

Cancer remains a major health challenge worldwide,and while progress has been made in research and treatment,much more needs to be done to combat this disease.Prevention strategies and early detection techniques offer hope for better outcomes,and new therapies hold promise for patients with advanced disease.The thesis discussed in this text focuses on the development of nanofactories for cancer treatment and the enhancement of enzyme prodrug chemo-immunotherapy.This thesis is divided into three chapters,each based on individual yet interconnected works that primarily aim to engineer therapeutic nanofactories for cancer treatment and develop a treatment strategy to enhance enzyme prodrug chemo-immunotherapy.As research continues,it is hoped that these innovative approaches will lead to further progress in the fight against cancer.The abstracts for each chapter are provided below:1st Chapter:Stimuli-responsive polymersomes are a class of nanostructures that have shown great potential as smart drug delivery systems and artificial nanoreactors.Herein,we developed a series of membrane-cross-linked(MCL)polymersomes that exhibit selective membrane permeability controlled by cross-linking density and tumor pH for stimuli-responsive drug delivery and controllable enzymatic reactions.We synthesized diblock copolym ers comprising poly(ethylene glycol)(PEG)and methacrylate monomers with piperidine or coumarin moieties,which self-assembled into polymersomes capable of encapsulating both small-molecule doxorubicin hydrochloride(DOX)and large-molecule glucose oxidase(GOD).Upon photo-crosslinking,the optimized cross-linking density and pH-responsive segments of the polymersomes conferred superior stability and ultra-pH-sensitive selective membrane permeability upon a pH decrease from 7.4 to 6.5.This pH-triggered enhanced membrane permeability allowed for the controlled release of the encapsulated drugs and the triggering of enzymatic reactions.Small molecules,such as DOX,glucose,and oxygen,could diffuse in and out of polymersomes,generating a massive amount of hydrogen peroxide(H2O2)under GOD catalysis,and synergistically inducing cancer cell death with the released DOX.This platform shows promise for cancer therapy and offers design insights for advanced stimuli-responsive polymersomes.2nd Chapter:Enzyme-activated prourug therapy is a promising approach for targeted drug delivery in cancer treatment.However,there is still a need for innovative treatments to overcome cancer’s challenges and improve patient outcomes.Our study introduces a novel proimmunostimulant that targets the immune system’s response to cancer cells,offering potential for cancer treatment.This proimmunostimulant,synthesized as(NLG-gal),can be activated by exogenous or endogenous βgalactosidase,enhancing immunotherapy in a targeted and effective way.In vitro experiments have demonstrated its enzymatic activation.Targeting the immune response to cancer cells could overcome limitations of traditional treatments.In vivo investigations will provide insights into its efficacy and safety,which will be discussed in the next chapter.This study could provide hope for the future of cancer treatment.3rd Chapter:Combination chemo-immunotherapy has been proven to be highly effective against tumors.However,the treatment is limited by severe immune-related adverse events and systemic toxicity.To address these limitations,we have developed a unique nanofactory-directed enzyme prodrug chemo-immunotherapy,which uses enzyme-loaded tumor-dilatable polymersomes with optimized membrane crosslinking density.Upon intravenous injection,the nanofactories passively accumulate at the tumor site,swelling from～100 nm to～200 nm under the trigger of tumor acidity,leading to prolonged retention of up to one week inside tumor tissues.The improved membrane permeability of the nanofactories allows hydrophilic small molecules to pass across the membranes while keeping the enzymes in the inner cavities.To administer the non-toxic prodrugs of chemo-immunotherapy,the nanofactories are used to selectively activate them at the tumor sites,with three administrations within 6 days.Activated chemotherapeutic drugs kill cancer cells and generate tumorassociated antigens to promote dendritic cell maturation,while activated indoleamine 2,3-dioxygenase 1 inhibitors reverse the immunosuppressive tumor microenvironment.The tumor-dilatable polymersome nanofactories with long-term intratumoral retention effectively suppress primary tumors while causing minimal systemic toxicity.Furthermore,the activation of antitumor immunity in mice completely inhibits distant tumors established after treatment.Overall,our approach offers a promising paradigm for improved enzyme prodrug chemo-immunotherapy with minimized systemic toxicity.