Tumor-dilated polymersome nanofactories for enhanced enzyme prodrug chemo-immunotherapy

A stimuli-responsive immunostimulant to activate chemo-immunotherapeutic effects by inducing DNA damage and STING activation

The integration of chemotherapy with systemic immune activation represents a promising approach to eradicate metastatic tumors. In this study, a stimuli-responsive immunostimulant nanoplatform (denoted as MV@Lip) was developed to synergistically activate antitumor immunity via chemotherapy-induced DNA damage and subsequent activation of the stimulator of interferon genes (STING) signaling pathway. The MV@Lip system encapsulates the chemotherapeutic agent mitoxantrone (Mit) and the STING agonist vadimezan (Vad) within a redox-responsive liposomal carrier. MV@Lip was indicated to enhance drug stability, while simultaneously promoting efficient co-delivery of both agents into tumor cells and suppressing tumor proliferation. Mechanistically, MV@Lip exerts its therapeutic efficacy through inducing DNA damage and triggering immunogenic cell death (ICD) to enhance tumor immunogenicity by releasing damage-associated molecular patterns (DAMPs). Concurrently, the released Vadimezan could activate the STING pathway, amplifying innate immune responses through the production of proinflammatory factors and the recruitment of immune effector cells. This concerted action facilitates the infiltration and activation of natural killer (NK) cells and T lymphocytes in the tumor microenvironment, ultimately leading to the suppression of both primary and metastatic tumors. These findings provide a compelling basis for advancing chemotherapeutic combinations as immune-stimulating strategies in the treatment of metastatic malignancies.

Smart nanocarriers for enzyme-activated prodrug therapy

Exogenous enzyme-activated prodrug therapy (EPT) is a potential cancer treatment strategy that delivers non-human enzymes into or on the surface of the cell and subsequently converts a non-toxic prodrug into an active cytotoxic substance at a specific location and time. The development of several pharmacological pairs based on EPT has been the focus of anticancer research for more than three decades. Numerous of these pharmacological pairs have progressed to clinical trials, and a few have achieved application in specific cancer therapies. The current review highlights the potential of enzyme-activated prodrug therapy as a promising anticancer treatment. Different microbial, plant, or viral enzymes and their corresponding prodrugs that advanced to clinical trials have been listed. Additionally, we discuss new trends in the field of enzyme-activated prodrug nanocarriers, including nanobubbles combined with ultrasound (NB/US), mesoscopic-sized polyion complex vesicles (PICsomes), nanoparticles, and extracellular vesicles (EVs), with special emphasis on smart stimuli-triggered drug release, hybrid nanocarriers, and the main application of nanotechnology in improving prodrugs.

Design and evaluation of nanoscale materials with programmed responsivity towards epigenetic enzymes

Self-assembled materials capable of modulating their assembly properties in response to specific enzymes play a pivotal role in advancing 'intelligent' encapsulation platforms for biotechnological applications. Here, we introduce a previously unreported class of synthetic nanomaterials that programmatically interact with histone deacetylase (HDAC) as the triggering stimulus for disassembly. These nanomaterials consist of co-polypeptides comprising poly(acetyl L-lysine) and poly(ethylene glycol) blocks. Under neutral pH conditions, they self-assemble into particles. The hydrodynamic diameters of particles were typically withing the range of 108-190 nm, depending on degree of acetylation of the hydrophobic block. However, their stability is compromised upon exposure to HDACs, depending on enzyme concentration and exposure time. Our investigation, utilizing HDAC8 as the model enzyme, revealed that the primary mechanism behind disassembly involves a decrease in amphiphilicity within the block copolymer due to the deacetylation of lysine residues within the particles' hydrophobic domains. To elucidate the response mechanism, we encapsulated a fluorescent dye within these nanoparticles. Upon incubation with HDAC, the nanoparticle structure collapsed, leading to controlled release of the dye over time. Notably, this release was not triggered by denatured HDAC8, other proteolytic enzymes like trypsin, or the co-presence of HDAC8 and its inhibitor. We also demonstrated the biocompatibility and cellular effects of these materials in the context of drug delivery in different types of anticancer cell lines, such as MIA PaCa-2, PANC-1, cancer like stem cells (CSCs), and non-cancerous HPNE cells. We observed that the release of a model drug (such as a STAT3 pathway inhibitor, Napabucasin) can be loaded into these nanoparticles, with >90% of the dosage can be released over 3 h under the influence of HDAC8 enzyme in a controlled fashion. Further, we conducted a comprehensive computational study to unveil the possible interaction mechanism between enzymes and particles. By drawing parallels to the mechanism of naturally occurring histone proteins, this research represents a pioneering step toward developing functional materials capable of harnessing the activity of epigenetic enzymes such as HDACs.

Redefining drug therapy: innovative approaches using catalytic compartments

INTRODUCTION

Rapid excretion of drug derivatives often results in short drug half-lives, necessitating frequent administrations. Catalytic compartments, also known as nano- and microreactors, offer a solution by providing confined environments for in situ production of therapeutic agents. Inspired by natural compartments, polymer-based catalytic compartments have been developed to improve reaction efficiency and enable site-specific therapeutic applications.

AREAS COVERED

Polymer-based compartments provide stability, permeability control, and responsiveness to stimuli, making them ideal for generating localized compounds/signals. These sophisticated systems, engineered to carry active compounds and enable selective molecular release, represent a significant advancement in pharmaceutical research. They mimic cellular functions, creating controlled catalytic environments for bio-relevant processes. This review explores the latest advancements in synthetic catalytic compartments, focusing on design approaches, building blocks, active molecules, and key bio-applications.

EXPERT OPINION

Catalytic compartments hold transformative potential in precision medicine by improving therapeutic outcomes through precise, on-site production of therapeutic agents. While promising, challenges like scalable manufacturing, biodegradability, and regulatory hurdles must be addressed to realize their full potential. Addressing these will be crucial for their successful application in healthcare.

Stimuli-Responsive Polymersomes: Reshaping the Immunosuppressive Tumor Microenvironment

The progression of cancer involves mutations in normal cells, leading to uncontrolled division and tissue destruction, highlighting the complexity of tumor microenvironments (TMEs). Immunotherapy has emerged as a transformative approach, yet the balance between efficacy and safety remains a challenge. Nanoparticles such as polymersomes offer the possibility to precisely target tumors, deliver drugs in a controlled way, effectively modulate the antitumor immunity, and notably reduce side effects. Herein, stimuli-responsive polymersomes, with capabilities for carrying multiple therapeutics, are highlighted for their potential in enhancing antitumor immunity through mechanisms like inducing immunogenic cell death and activating STING (stimulator of interferon genes), etc. The recent progress of utilizing stimuli-responsive polymersomes to reshape the TME is reviewed here. The advantages and limitations to applied stimuli-responsive polymersomes are outlined. Additionally, challenges and future prospects in leveraging polymersomes for cancer therapy are discussed, emphasizing the need for future research and clinical translation.

Glycooligomer-Functionalized Catalytic Nanocompartments Co-Loaded with Enzymes Support Parallel Reactions and Promote Cell Internalization

A major shortcoming associated with the application of enzymes in drug synergism originates from the lack of site-specific, multifunctional nanomedicine. This study introduces catalytic nanocompartments (CNCs) made of a mixture of PDMS-b-PMOXA diblock copolymers, decorated with glycooligomer tethers comprising eight mannose-containing repeating units and coencapsulating two enzymes, providing multifunctionality by their in situ parallel reactions. Beta-glucuronidase (GUS) serves for local reactivation of the drug hymecromone, while glucose oxidase (GOx) induces cell starvation through glucose depletion and generation of the cytotoxic H2O2. The insertion of the pore-forming peptide, melittin, facilitates diffusion of substrates and products through the membranes. Increased cell-specific internalization of the CNCs results in a substantial decrease in HepG2 cell viability after 24 h, attributed to simultaneous production of hymecromone and H2O2. Such parallel enzymatic reactions taking place in nanocompartments pave the way to achieve efficient combinatorial cancer therapy by enabling localized drug production along with reactive oxygen species (ROS) elevation.

Design and Evaluation of Nanoscale Materials with Programmed Responsivity towards Epigenetic Enzymes

Self-assembled materials capable of modulating their assembly properties in response to specific enzymes play a pivotal role in advancing 'intelligent' encapsulation platforms for biotechnological applications. Here, we introduce a previously unreported class of synthetic nanomaterials that programmatically interact with histone deacetylase (HDAC) as the triggering stimulus for disassembly. These nanomaterials consist of co-polypeptides comprising poly (acetyl L-lysine) and poly(ethylene glycol) blocks. Under neutral pH conditions, they self-assemble into particles. However, their stability is compromised upon exposure to HDACs, depending on enzyme concentration and exposure time. Our investigation, utilizing HDAC8 as the model enzyme, revealed that the primary mechanism behind disassembly involves a decrease in amphiphilicity within the block copolymer due to the deacetylation of lysine residues within the particles' hydrophobic domains. To elucidate the response mechanism, we encapsulated a fluorescent dye within these nanoparticles. Upon incubation with HDAC, the nanoparticle structure collapsed, leading to controlled release of the dye over time. Notably, this release was not triggered by denatured HDAC8, other proteolytic enzymes like trypsin, or the co-presence of HDAC8 and its inhibitor. We further demonstrated the biocompatibility and cellular effects of these materials and conducted a comprehensive computational study to unveil the possible interaction mechanism between enzymes and particles. By drawing parallels to the mechanism of naturally occurring histone proteins, this research represents a pioneering step toward developing functional materials capable of harnessing the activity of epigenetic enzymes such as HDACs.

Nanomedicines: Emerging Platforms in Smart Chemotherapy Treatment-A Recent Review

Cancer continues to pose one of the most critical challenges in global healthcare. Despite the wide array of existing cancer drugs, the primary obstacle remains in selectively targeting and eliminating cancer cells while minimizing damage to healthy ones, thereby reducing treatment side effects. The revolutionary approach of utilizing nanomaterials for delivering cancer therapeutic agents has significantly enhanced the efficacy and safety of chemotherapeutic drugs. This crucial shift is attributed to the unique properties of nanomaterials, enabling nanocarriers to transport therapeutic agents to tumor sites in both passive and active modes, while minimizing drug elimination from delivery systems. Furthermore, these nanocarriers can be designed to respond to internal or external stimuli, thus facilitating controlled drug release. However, the production of nanomedications for cancer therapy encounters various challenges that can impede progress in this field. This review aims to provide a comprehensive overview of the current state of nanomedication in cancer treatment. It explores a variety of nanomaterials, focusing on their unique properties that are crucial for overcoming the limitations of conventional chemotherapy. Additionally, the review delves into the properties and functionalities of nanocarriers, highlighting their significant impact on the evolution of nanomedicine. It also critically assesses recent advancements in drug delivery systems, covering a range of innovative delivery methodologies. Finally, the review succinctly addresses the challenges encountered in developing nanomedications, offering insightful perspectives to guide future research in this field.

Polymersome Membrane Engineering with Active Targeting or Controlled Permeability for Responsive Drug Delivery

Polymersomes have been extensively investigated for drug delivery as nanocarriers for two decades due to a series of advantages including high stability under physiological conditions, simultaneous encapsulation of hydrophilic and hydrophobic drugs inside inner cavities and membranes, respectively, and facile adjustment of membrane and surface properties, as well as controlled drug release through incorporation of stimuli-responsive components. Despite these features, polymersome nanocarriers frequently suffer from nontargeting delivery and poor membrane permeability. In recent years, polymersomes have been functionalized for more efficient drug delivery. The surface shells were explored to be modified with diverse active targeting groups to improve disease-targeting delivery. The membrane permeability of the polymersomes was adjusted by incorporation of the stimuli-responsive components for smart controlled transportation of the encapsulated drugs. Therefore, being the polymersome-biointerface, tailorable properties can be introduced by its carefully modulated engineering. This review elaborates on the role of polymersome membranes as a platform to incorporate versatile features. First, we discuss how surface functionalization facilitates the directional journey to the targeting sites toward specific diseases, cells, or intracellular organelles via active targeting. Moreover, recent advances in the past decade related to membrane permeability to control drug release are also summarized. We finally discuss future development to promote polymersomes as in vivo drug delivery nanocarriers.

The D-amino acid oxidase-carbon nanotubes: evaluation of cytotoxicity and biocompatibility of a potential anticancer nanosystem

The 'enzyme prodrug therapy' represents a promising strategy to overcome limitations of current cancer treatments by the systemic administration of prodrugs, converted by a foreign enzyme into an active anticancer compound directly in tumor sites. One example is D-amino acid oxidase (DAAO), a dimeric flavoenzyme able to catalyze the oxidative deamination of D-amino acids with production of hydrogen peroxide, a reactive oxygen species (ROS), able to favor cancer cells death. A DAAO variant containing five aminoacidic substitutions (mDAAO) was demonstrated to possess a better therapeutic efficacy under low O2 concentration than wild-type DAAO (wtDAAO). Recently, aiming to design promising nanocarriers for DAAO, multi-walled carbon nanotubes (MWCNTs) were functionalized with polyethylene glycol (PEG) to reduce their tendency to aggregation and to improve their biocompatibility. Here, wtDAAO and mDAAO were adsorbed on PEGylated MWCNTs and their activity and cytotoxicity were tested. While PEG-MWCNTs-DAAOs have shown a higher activity than pristine MWCNTs-DAAO (independently on the DAAO variant used), PEG-MWCNTs-mDAAO showed a higher cytotoxicity than PEG-MWCNTs-wtDAAO at low O2 concentration. In order to evaluate the nanocarriers' biocompatibility, PEG-MWCNTs-DAAOs were incubated in human serum and the composition of protein corona was investigated via nLC-MS/MS, aiming to characterize both soft and hard coronas. The mDAAO variant has influenced the bio-corona composition in both number of proteins and presence of opsonins and dysopsonins: notably, the soft corona of PEG-MWCNTs-mDAAO contained less proteins and was more enriched in proteins able to inhibit the immune response than PEG-MWCNTs-wtDAAO. Considering the obtained results, the PEGylated MWCNTs conjugated with the mDAAO variant seems a promising candidate for a selective antitumor oxidative therapy: under anoxic-like conditions, this novel drug delivery system showed a remarkable cytotoxic effect controlled by the substrate addition, against different tumor cell lines, and a bio-corona composition devoted to prolong its blood circulation time, thus improving the drug's biodistribution.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03568-1.

Nanotechnology for next-generation cancer immunotherapy: State of the art and future perspectives

Over the past decade, immunotherapy aiming to activate an effective antitumor immune response has ushered in a new era of cancer treatment. However, the efficacy of cancer immunotherapy is limited by low response rates and high systemic toxicity. Nanotechnology is an encouraging platform for the development of next-generation cancer immunotherapy to effectively treat advanced cancer. Nanotechnology-enabled immunotherapy has remarkable advantages, ranging from the increased bioavailability and stability of immunotherapeutic agents to the enhanced activation of immune cells and favorable safety profiles. Nanotechnology-enabled immunotherapy can target solid tumors through reprogramming or stimulating immune cells (i.e., nanovaccines); modulating the immunosuppressive tumor microenvironment; or targeting tumor cells and altering their responses to immune cells to generate effective antitumor immunity. In this Oration, I introduce the advanced strategies currently being pursued by our laboratory and other groups to improve the therapeutic efficacy of cancer immunotherapy and discuss the potential challenges and future directions.

Fabrication of Polymersomes: A Macromolecular Architecture in Nanotherapeutics

In consideration of the issues of drug delivery systems, the artificial vesicle structures composed of block copolymers called polymersomes recently gained considerable attention. The possibility of tuning the mechanical parameter and increasing the scale-up production of polymersomes led to its wide application in healthcare. Bearing in mind the disease condition, the structure and properties of the polymersomes could be tuned to serve the purpose. Furthermore, specific ligands can be incorporated on the vesicular surface to induce smart polymersomes, thus improving targeted delivery. The synthesis method and surface functionalization are the two key aspects that determine the versatility of biological applications as they account for stability, specific targeting, degradability, biocompatibility, and bioavailability. A perfectly aligned polymer vesicle can mimic the cells/organelles and function by avoiding cytotoxicity. This supramolecular structure can carry and deliver payloads of a wide range, including drugs, proteins, and genes, contributing to the construction of next-generation therapeutics. These aspects promote the potential use of such components as a framework to approach damaged tissue while maintaining healthy environments during circulation. Herein, this article concentrates specifically on the drug delivery applications of polymersomes.

Aptamer-conjugated nano-liposome for immunogenic chemotherapy with reversal of immunosuppression

Cancer cells have various immune evasion mechanisms that resist the immune cells by reprogramming the tumor microenvironment (TME), such as programmed death-ligand 1 (PD-L1) and indoleamine 2,3-dioxygenase-1 (IDO1) overexpression. One of the approaches to restore antitumor immune response by T-cells is through induction of immunogenic cell death (ICD). Thus, drug carrier containing IDO1 siRNA and ICD inducer would be effective anticancer regimen to modulate the immunosuppressive TME by reversing the IDO1-mediated immunosuppression in a synergistic combination with ICD induction. However, numerous nanocarrier platforms for co-delivery of multiple drugs mostly depend on the enhanced permeation and retention (EPR), which is insufficient to achieve selectivity in tumor sites harboring various types of cells. We designed a targeted drug delivery system using nano-sized liposomes functionalized with anti-CD44 and anti-PD-L1 DNA aptamers, which target breast cancer cells and inhibit PD-1/PD-L1 interaction between cancer cells and T-cells. To reverse immunosuppressive TME and reactivate immune response, cancer-targeting nano-liposomes were prepared to contain immunogenic cell death inducer (Doxorubicin, DOX) and IDO1 siRNA, namely Aptm[DOX/IDO1]. The Aptm[DOX/IDO1] specifically delivered the loaded DOX and IDO1 siRNA into target breast cancer cells through aptamer-mediated endocytosis. Cancer-targeted DOX/IDO1 siRNA delivery enhanced ICD and suppressed IDO1 expression with significantly high toxicity in cancer cells. We demonstrated that Aptm[DOX/IDO1] could achieve synergistic antitumor effects by facilitating ICD response and simultaneous reversal of the immunosuppressive TME with IDO1 knockdown in the subcutaneous breast cancer model mice, thus reducing tumor size. These antitumor effects were exerted with intratumoral infiltration of CD8⁺ cytotoxic T lymphocyte as well as attenuation of regulatory T-cell recruitment in the tumor sites. We further proved that our Aptm[DOX/IDO1] strategy significantly reduced tumor metastasis in tumor-xenograft mice through a synergistic combination of cancer cell-targeted ICD induction and reversal of the IDO1-mediated immunosuppressive TME. Our nanocarrier platform based on cationic liposomes containing DOX and IDO1 siRNA, which are conjugated with two DNA aptamers targeting the cancer cell surface, accomplished synergistic chemoimmunotherapy through tumor-specific immune modulation into immune-favorable TME in vivo.

Bioorthogonal micellar nanoreactors for prodrug cancer therapy using an inverse-electron-demand Diels-Alder reaction

Block copolymer micelles functionalized with tetrazine groups can act as nanoreactors to activate a trans-cyclooctene-functionalized prodrug for releasing anticancer drugs via a bioorthogonal inverse-electron-demand Diels-Alder (IEDDA) reaction. In addition, the IEDDA reaction can be accelerated in the micellar nanoreactor system compared to the free tetrazine system. Moreover, In vivo prodrug activation in a mouse tumor model led to the inhibition of tumor growth without significant systemic toxicity. These results demonstrated their potential for applications as bioorthogonal micellar nanoreactors for cancer chemotherapy.

Supramolecular Shear-Thinning Glycopeptide Hydrogels for Injectable Enzyme Prodrug Therapy Applications

Transplantable catalytic reactors have attracted considerable attention as therapeutic biomedical materials. However, existing transplantable reactors such as biocatalytic films are limited by their invasiveness. Here, we report the fabrication of biocatalytic supramolecular hydrogels via self-assembly of amphiphilic glycopeptides. We show that the hydrogels have shear-thinning properties, demonstrating their potential to be administered using a syringe. Enzymes can be loaded into the hydrogels by simply adding enzyme solution, and the enzyme-loaded hydrogels can transform a prodrug into an anticancer drug that inhibits tumor cell growth. This study demonstrates the potential of these biocatalytic hydrogels as injectable therapeutic reactors for enzyme prodrug therapy.

Novel polysaccharide building hybrid nanoparticles: remodelling TAMs to target ERα-positive breast cancer

With the increasing number of oncology patients and the use of chemotherapeutic agents, tumour multidrug resistance is becoming more and more prevalent. The search for new tumour treatment strategies to overcome tumour multidrug resistance is urgent. In this study, we designed GSH and ROS dual-responsive tumour-associated macrophages (TAMs)-targeted nanoparticles (NPs) for the co-delivery of the clinical first-line anti-breast cancer chemotherapy drug paclitaxel (PTX) and baicalin (Bai), which re-educates TAMs to alter their phenotype. We synthesised oligohyaluronic acid-mannose-folic acid (oHA-Man-FA, HMF) and astragalus polysaccharide-dithiodipropionic acid-paeoniflorol (APS-S-Pae, ASP), two hybrid materials that can self-assemble in water to form hybrid nanoparticles (HP-NPs) co-loaded with paclitaxel and baicalin (HP-NPs@PTX/Bai). The experimental results show that our designed hybrid nanoparticles can be specifically released in the tumour microenvironment and deliver the antitumor drug PTX as well as Bai, which reshapes the phenotype of TAMs, to the tumour site. The hybrid nanoparticles not only effectively re-educated TAMs from M2 TAM to M1 TAM, but also ameliorated the cytotoxic side effects caused by free PTX and provided better tumour suppression than free PTX and HP.