Well-Defined Mannosylated Polymer for Peptide Vaccine Delivery with Enhanced Antitumor Immunity

Topology-Oriented Lymph Node Drainage of Dendritic Polymer-TLR Agonist Conjugates to Enhance Vaccine Immunogenicity

Strategically targeting lymph nodes (LNs) to orchestrate the initiation and regulation of adaptive immune responses is one of the most pressing challenges in the context of vaccination. Herein, a series of polymer-TLR agonist conjugates (PTACs) is developed to investigate the impact of dendritic-topological characteristics on their LN targeting activity in vivo, and their molecular weight (MW) on their pharmacokinetics in support of their LN homing. Notably, the dendritic 6-arm PTAC with a MW of 60 kDa (6A-PTAC-60k) rapidly delivered cargo to draining LNs after administration to peripheral tissues. Specifically, this topologic structure ameliorated the targeting behavior within lymphatic vessels and LNs, including an elevated amount of TLR7/8 agonist delivered to the LNs, an improved distribution pattern among barrier cells and immune cells, increased permeability, and prolonged retention. Furthermore, the 6A-PTAC-60k formulation induced broad antibody and T cell responses, enhancing vaccine immunogenicity and suppressing tumor growth. The results revealed that both the topology and MW of polymers are crucial factors for immunoadjuvant distribution and their functional activity in the draining LNs, which, in turn, enhanced the immunogenicity of the vaccine formulation. This study may provide a chemical and structural basis for optimizing the design of immunoadjuvant delivery systems.

Advanced Polymeric Nanoparticles for Cancer Immunotherapy: Materials Engineering, Immunotherapeutic Mechanism and Clinical Translation

Cancer immunotherapy, which leverages immune system components to treat malignancies, has emerged as a cornerstone of contemporary therapeutic strategies. Yet, critical concerns about the efficacy and safety of cancer immunotherapies remain formidable. Nanotechnology, especially polymeric nanoparticles (PNPs), offers unparalleled flexibility in manipulation-from the chemical composition and physical properties to the precision control of nanoassemblies. PNPs provide an optimal platform to amplify the potency and minimize systematic toxicity in a broad spectrum of immunotherapeutic modalities. In this comprehensive review, the basics of polymer chemistry, and state-of-the-art designs of PNPs from a physicochemical standpoint for cancer immunotherapy, encompassing therapeutic cancer vaccines, in situ vaccination, adoptive T-cell therapies, tumor-infiltrating immune cell-targeted therapies, therapeutic antibodies, and cytokine therapies are delineated. Each immunotherapy necessitates distinctively tailored design strategies in polymeric nanoplatforms. The extensive applications of PNPs, and investigation of their mechanisms of action for enhanced efficacy are particularly focused on. The safety profiles of PNPs and clinical research progress are discussed. Additionally, forthcoming developments and emergent trends of polymeric nano-immunotherapeutics poised to transform cancer treatment paradigms into clinics are explored.

Prophylactic and therapeutic cancer vaccine with continuous localized immunomodulation

Selective in vivo immune cell manipulation offers a promising strategy for cancer vaccines. In this context, spatiotemporal control over recruitment of specific cells, and their direct exposure to appropriate immunoadjuvants and antigens are key to effective cancer vaccines. We present an implantable 3D-printed cancer vaccine platform called the 'NanoLymph' that enables spatiotemporally-controlled recruitment and manipulation of immune cells in a subcutaneous site. Leveraging two reservoirs each for continuous immunoadjuvant release or antigen presentation, the NanoLymph attracts dendritic cells (DCs) on site and exposes them to tumor-associated antigens. Upon local antigen-specific activation, DCs are mobilized to initiate a systemic immune response. NanoLymph releasing granulocyte-macrophage colony-stimulating factor and CpG-oligodeoxynucleotides with irradiated whole cell tumor lysate inhibited tumor growth of B16F10 murine melanoma in a prophylactic and therapeutic vaccine setting. Overall, this study presents the NanoLymph as a versatile cancer vaccine development platform with replenishable and controlled local release of antigens and immunoadjuvants.

Bioresponsive Immunotherapeutic Materials

The human immune system is an interaction network of biological processes, and its dysfunction is closely associated with a wide array of diseases, such as cancer, infectious diseases, tissue damage, and autoimmune diseases. Manipulation of the immune response network in a desired and controlled fashion has been regarded as a promising strategy for maximizing immunotherapeutic efficacy and minimizing side effects. Integration of "smart" bioresponsive materials with immunoactive agents including small molecules, biomacromolecules, and cells can achieve on-demand release of agents at targeted sites to reduce overdose-related toxicity and alleviate off-target effects. This review highlights the design principles of bioresponsive immunotherapeutic materials and discusses the critical roles of controlled release of immunoactive agents from bioresponsive materials in recruiting, housing, and manipulating immune cells for evoking desired immune responses. Challenges and future directions from the perspective of clinical translation are also discussed.

Advancements and Challenges in Peptide-Based Cancer Vaccination: A Multidisciplinary Perspective

With the continuous advancements in tumor immunotherapy, researchers are actively exploring new treatment methods. Peptide therapeutic cancer vaccines have garnered significant attention for their potential in improving patient outcomes. Despite its potential, only a single peptide-based cancer vaccine has been approved by the U.S. Food and Drug Administration (FDA). A comprehensive understanding of the underlying mechanisms and current development status is crucial for advancing these vaccines. This review provides an in-depth analysis of the production principles and therapeutic mechanisms of peptide-based cancer vaccines, highlights the commonly used peptide-based cancer vaccines, and examines the synergistic effects of combining these vaccines with immunotherapy, targeted therapy, radiotherapy, and chemotherapy. While some studies have yielded suboptimal results, the potential of combination therapies remains substantial. Additionally, we addressed the management and adverse events associated with peptide-based cancer vaccines, noting their relatively higher safety profile compared to traditional radiotherapy and chemotherapy. Lastly, we also discussed the roles of adjuvants and targeted delivery systems in enhancing vaccine efficacy. In conclusion, this review comprehensively outlines the current landscape of peptide-based cancer vaccination and underscores its potential as a pivotal immunotherapy approach.

Lipid- and Polymer-Based Nanocarrier Platforms for Cancer Vaccine Delivery

Cancer immunotherapy has gained popularity in recent years in the search for effective treatment modalities for various malignancies, particularly those that are resistant to conventional chemo- and radiation therapy. Cancer vaccines target the cancer-immunity cycle by boosting the patient's own immune system to recognize and kill cancer cells, thus serving as both preventative and curative therapeutic tools. Among the different types of cancer vaccines, those based on nanotechnology have shown great promise in advancing the field of cancer immunotherapy. Lipid-based nanoparticles (NPs) have become the most advanced platforms for cancer vaccine delivery, but polymer-based NPs have also received considerable interest. This Review aims to provide an overview of the nanotechnology-enabled cancer vaccine landscape, focusing on recent advances in lipid- and polymer-based nanovaccines and their hybrid structures and discussing the challenges against the clinical translation of these important nanomedicines.

Engineering customized nanovaccines for enhanced cancer immunotherapy

Nanovaccines have gathered significant attention for their potential to elicit tumor-specific immunological responses. Despite notable progress in tumor immunotherapy, nanovaccines still encounter considerable challenges such as low delivery efficiency, limited targeting ability, and suboptimal efficacy. With an aim of addressing these issues, engineering customized nanovaccines through modification or functionalization has emerged as a promising approach. These tailored nanovaccines not only enhance antigen presentation, but also effectively modulate immunosuppression within the tumor microenvironment. Specifically, they are distinguished by their diverse sizes, shapes, charges, structures, and unique physicochemical properties, along with targeting ligands. These features of nanovaccines facilitate lymph node accumulation and activation/regulation of immune cells. This overview of bespoke nanovaccines underscores their potential in both prophylactic and therapeutic applications, offering insights into their future development and role in cancer immunotherapy.

Peptide-conjugated Nanoparticle Platforms for Targeted Delivery, Imaging, and Biosensing Applications

Peptides have become an indispensable tool in engineering of multifunctional nanostructure platforms for biomedical applications such as targeted drug and gene delivery, imaging and biosensing. They can be covalently incorporated into a variety of nanoparticles (NPs) including polymers, metallic nanoparticles, and others. Using different bioconjugation techniques, multifunctional peptide-modified NPs can be formulated to produce therapeutical and diagnostic platforms offering high specificity, lower toxicity, biocompatibility, and stimuli responsive behavior. Targeting peptides can direct the nanoparticles into specific tissues for targeted drug and gene delivery and imaging applications due to their specificity towards certain receptors. Furthermore, due to their stimuli-responsive features, they can offer controlled release of therapeutics into desired sites of disease. In addition, peptide-based biosensors and imaging agents can provide non-invasive detection and monitoring of diseases including cancer, infectious diseases, and neurological disorders. In this review, we covered the design and formulation of recent peptide-based NP platforms, as well as their utilization in in vitro and in vivo applications such as targeted drug and gene delivery, targeting, sensing, and imaging applications. In the end, we provided the future outlook to design new peptide conjugated nanomaterials for biomedical applications.

Polymeric Nanoparticles for Drug Delivery

The recent emergence of nanomedicine has revolutionized the therapeutic landscape and necessitated the creation of more sophisticated drug delivery systems. Polymeric nanoparticles sit at the forefront of numerous promising drug delivery designs, due to their unmatched control over physiochemical properties such as size, shape, architecture, charge, and surface functionality. Furthermore, polymeric nanoparticles have the ability to navigate various biological barriers to precisely target specific sites within the body, encapsulate a diverse range of therapeutic cargo and efficiently release this cargo in response to internal and external stimuli. However, despite these remarkable advantages, the presence of polymeric nanoparticles in wider clinical application is minimal. This review will provide a comprehensive understanding of polymeric nanoparticles as drug delivery vehicles. The biological barriers affecting drug delivery will be outlined first, followed by a comprehensive description of the various nanoparticle designs and preparation methods, beginning with the polymers on which they are based. The review will meticulously explore the current performance of polymeric nanoparticles against a myriad of diseases including cancer, viral and bacterial infections, before finally evaluating the advantages and crucial challenges that will determine their wider clinical potential in the decades to come.

Mannosylated STING Agonist Drugamers for Dendritic Cell-Mediated Cancer Immunotherapy

The Stimulator of Interferon Genes (STING) pathway is a promising target for cancer immunotherapy. Despite recent advances, therapies targeting the STING pathway are often limited by routes of administration, suboptimal STING activation, or off-target toxicity. Here, we report a dendritic cell (DC)-targeted polymeric prodrug platform (polySTING) that is designed to optimize intracellular delivery of a diamidobenzimidazole (diABZI) small-molecule STING agonist while minimizing off-target toxicity after parenteral administration. PolySTING incorporates mannose targeting ligands as a comonomer, which facilitates its uptake in CD206+/mannose receptor+ professional antigen-presenting cells (APCs) in the tumor microenvironment (TME). The STING agonist is conjugated through a cathepsin B-cleavable valine-alanine (VA) linker for selective intracellular drug release after receptor-mediated endocytosis. When administered intravenously in tumor-bearing mice, polySTING selectively targeted CD206+/mannose receptor+ APCs in the TME, resulting in increased cross-presenting CD8+ DCs, infiltrating CD8+ T cells in the TME as well as maturation across multiple DC subtypes in the tumor-draining lymph node (TDLN). Systemic administration of polySTING slowed tumor growth in a B16-F10 murine melanoma model as well as a 4T1 murine breast cancer model with an acceptable safety profile. Thus, we demonstrate that polySTING delivers STING agonists to professional APCs after systemic administration, generating efficacious DC-driven antitumor immunity with minimal side effects. This new polymeric prodrug platform may offer new opportunities for combining efficient targeted STING agonist delivery with other selective tumor therapeutic strategies.

Design and Evaluation of Synthetic Delivery Formulations for Peptide-Based Cancer Vaccines

With the recent advances in neoantigen identification, peptide-based cancer vaccines offer substantial potential in the field of immunotherapy. However, rapid clearance, low immunogenicity, and insufficient antigen-presenting cell (APC) uptake limit the efficacy of peptide-based cancer vaccines. This review explores the barriers hindering vaccine efficiency, highlights recent advancements in synthetic delivery systems, and features strategies for the key delivery steps of lymph node (LN) drainage, APC delivery, cross-presentation strategies, and adjuvant incorporation. This paper also discusses the design of preclinical studies evaluating vaccine efficiency, including vaccine administration routes and murine tumor models.

GalNAc- or Mannose-PEG-Functionalized Polyplexes Enable Effective Lectin-Mediated DNA Delivery

A cationic, dendrimer-like oligo(aminoamide) carrier with four-arm topology based on succinoyl tetraethylene pentamine and histidines, cysteines, and N-terminal azido-lysines was screened for plasmid DNA delivery on various cell lines. The incorporated azides allow modification with various shielding agents of different polyethylene glycol (PEG) lengths and/or different ligands by copper-free click reaction, either before or after polyplex formation. Prefunctionalization was found to be advantageous over postfunctionalization in terms of nanoparticle formation, stability, and efficacy. A length of 24 ethylene oxide repetition units and prefunctionalization of ≥50% of azides per carrier promoted optimal polyplex shielding. PEG shielding resulted in drastically reduced DNA transfer, which could be successfully restored by active lectin targeting via novel GalNAc or mannose ligands, enabling enhanced receptor-mediated endocytosis of the carrier system. The involvement of the asialoglycoprotein receptor (ASGPR) in the uptake of GalNAc-functionalized polyplexes was confirmed in the ASGPR-positive hepatocarcinoma cell lines HepG2 and Huh7. Mannose-modified polyplexes showed superior cellular uptake and transfection efficacy compared to unmodified and shielded polyplexes in mannose-receptor-expressing dendritic cell-like DC2.4 cells.

Transcriptional Targeting of Dendritic Cells Using an Optimized Human Fascin1 Gene Promoter

Deeper knowledge about the role of the tumor microenvironment (TME) in cancer development and progression has resulted in new strategies such as gene-based cancer immunotherapy. Whereas some approaches focus on the expression of tumoricidal genes within the TME, DNA-based vaccines are intended to be expressed in antigen-presenting cells (e.g., dendritic cells, DCs) in secondary lymphoid organs, which in turn induce anti-tumor T cell responses. Besides effective delivery systems and the requirement of appropriate adjuvants, DNA vaccines themselves need to be optimized regarding efficacy and selectivity. In this work, the concept of DC-focused transcriptional targeting was tested by applying a plasmid encoding for the luciferase reporter gene under the control of a derivative of the human fascin1 gene promoter (pFscnLuc), comprising the proximal core promoter fused to the normally more distantly located DC enhancer region. DC-focused activity of this reporter construct was confirmed in cell culture in comparison to a standard reporter vector encoding for luciferase under the control of the strong ubiquitously active cytomegalovirus promoter and enhancer (pCMVLuc). Both plasmids were also compared upon intravenous administration in mice. The organ- and cell type-specific expression profile of pFscnLuc versus pCMVLuc demonstrated favorable activity especially in the spleen as a central immune organ and within the spleen in DCs.

Advances in Polymeric Micelles: Responsive and Targeting Approaches for Cancer Immunotherapy in the Tumor Microenvironment

In recent years, to treat a diverse array of cancer forms, considerable advancements have been achieved in the field of cancer immunotherapies. However, these therapies encounter multiple challenges in clinical practice, such as high immune-mediated toxicity, insufficient accumulation in cancer tissues, and undesired off-target reactions. To tackle these limitations and enhance bioavailability, polymer micelles present potential solutions by enabling precise drug delivery to the target site, thus amplifying the effectiveness of immunotherapy. This review article offers an extensive survey of recent progress in cancer immunotherapy strategies utilizing micelles. These strategies include responsive and remodeling approaches to the tumor microenvironment (TME), modulation of immunosuppressive cells within the TME, enhancement of immune checkpoint inhibitors, utilization of cancer vaccine platforms, modulation of antigen presentation, manipulation of engineered T cells, and targeting other components of the TME. Subsequently, we delve into the present state and constraints linked to the clinical utilization of polymeric micelles. Collectively, polymer micelles demonstrate excellent prospects in tumor immunotherapy by effectively addressing the challenges associated with conventional cancer immunotherapies.

Biological function, regulatory mechanism, and clinical application of mannose in cancer

Studies examining the regulatory roles and clinical applications of monosaccharides other than glucose in cancer have been neglected. Mannose, a common type of monosaccharide found in human body fluids and tissues, primarily functions in protein glycosylation rather than carbohydrate metabolism. Recent research has demonstrated direct anticancer effects of mannose in vitro and in vivo. Simply supplementing cell culture medium or drinking water with mannose achieved these effects. Moreover, mannose enhances the effectiveness of current cancer treatments including chemotherapy, radiotherapy, targeted therapy, and immune therapy. Besides the advancements in basic research on the anticancer effects of mannose, recent studies have reported its application as a biomarker for cancer or in the delivery of anticancer drugs using mannose-modified drug delivery systems. This review discusses the progress made in understanding the regulatory roles of mannose in cancer progression, the mechanisms underlying its anticancer effects, and its current application in cancer diagnosis and treatment.

Copolymer Micelles: A Focus on Recent Advances for Stimulus-Responsive Delivery of Proteins and Peptides

Historically used for the delivery of hydrophobic drugs through core encapsulation, amphiphilic copolymer micelles have also more recently appeared as potent nano-systems to deliver protein and peptide therapeutics. In addition to ease and reproducibility of preparation, micelles are chemically versatile as hydrophobic/hydrophilic segments can be tuned to afford protein immobilization through different approaches, including non-covalent interactions (e.g., electrostatic, hydrophobic) and covalent conjugation, while generally maintaining protein biological activity. Similar to many other drugs, protein/peptide delivery is increasingly focused on stimuli-responsive nano-systems able to afford triggered and controlled release in time and space, thereby improving therapeutic efficacy and limiting side effects. This short review discusses advances in the design of such micelles over the past decade, with an emphasis on stimuli-responsive properties for optimized protein/peptide delivery.

A Universal Cyclodextrin-Based Nanovaccine Platform Delivers Epitope Peptides for Enhanced Antitumor Immunity

Currently, there is still an intense demand for a simple and scalable delivery platform for peptide-based cancer vaccines. Herein, a cyclodextrin-based polymer nanovaccine platform (CDNP) is designed for the codelivery of peptides with two immune adjuvants [the Toll-like receptor (TLR)7/8 agonist R848 and the TLR9 agonist CpG] that is broadly applicable to epitope peptides with diverse sequences. Specifically, the cyclodextrin-based polymers are covalently linked to epitope peptides via a bioreactive bond-containing cross-linker (PNC-DTDE-PNC) and then physically load with R848 and CpG to obtain CDNP. The CDNP efficiently accumulats in the lymph nodes (LNs), greatly facilitating antigen capture and cross-presentation by antigen-presenting cells. The immunogenicity of the epitope peptides is significantly enhanced by the codelivery and synergy of the adjuvants, and the CDNP shows the ability to inhibit tumor progression in diverse tumor-bearing mouse models. It is concluded that CDNP holds promise as an optimized peptide-based cancer vaccine platform.

Fused Cytomembrane-Camouflaged Nanoparticles for Tumor-Specific Immunotherapy

Tumor immunotherapy is commonly hindered by inefficient delivery and presentation of tumor antigens as well as immunosuppressive tumor microenvironment. To overcome these barriers, a tumor-specific nanovaccine capable of delivering tumor antigens and adjuvants to antigen-presenting cells and modulating the immune microenvironment to elicit strong antitumor immunity is reported. This nanovaccine, named FCM@4RM, is designed by coating the nanocore (FCM) with a bioreconstituted cytomembrane (4RM). The 4RM, which is derived from fused cells of tumorous 4T1 cells and RAW264.7 macrophages, enables effective antigen presentation and stimulation of effector T cells. FCM is self-assembled from Fe(II), unmethylated cytosine-phosphate-guanine oligodeoxynucleotide (CpG), and metformin (MET). CpG, as the stimulator of toll-like receptor 9, induces the production of pro-inflammatory cytokine and the maturation of cytotoxic T lymphocytes (CTLs), thereby enhancing antitumor immunity. Meanwhile, MET functions as the programmed cell death ligand 1 inhibitor and can restore the immune responses of T cells against tumor cells. Therefore, FCM@4RM exhibits high targeting capabilities toward homologous tumors that develop from 4T1 cells. This work offers a paradigm for developing a nanovaccine that systematically regulates multiple immune-related processes to achieve optimal antitumor immunotherapy.

Rethinking Antigen Source: Cancer Vaccines Based on Whole Tumor Cell/tissue Lysate or Whole Tumor Cell

Cancer immunotherapies have improved human health, and one among the important technologies for cancer immunotherapy is cancer vaccine. Antigens are the most important components in cancer vaccines. Generally, antigens in cancer vaccines can be divided into two categories: pre-defined antigens and unidentified antigens. Although, cancer vaccines loaded with predefined antigens are commonly used, cancer vaccine loaded with mixed unidentified antigens, especially whole cancer cells or cancer cell lysates, is a very promising approach, and such vaccine can obviate some limitations in cancer vaccines. Their advantages include, but are not limited to, the inclusion of pan-spectra (all or most kinds of) antigens, inducing pan-clones specific T cells, and overcoming the heterogeneity of cancer cells. In this review, the recent advances in cancer vaccines based on whole-tumor antigens, either based on whole cancer cells or whole cancer cell lysates, are summarized. In terms of whole cancer cell lysates, the focus is on applying whole water-soluble cell lysates as antigens. Recently, utilizing the whole cancer cell lysates as antigens in cancer vaccines has become feasible. Considering that pre-determined antigen-based cancer vaccines (mainly peptide-based or mRNA-based) have various limitations, developing cancer vaccines based on whole-tumor antigens is a promising alternative.

A mannosylated polymer with endosomal release properties for peptide antigen delivery

Peptide cancer vaccines have had limited clinical success despite their safety, characterization and production advantages. We hypothesize that the poor immunogenicity of peptides can be surmounted by delivery vehicles that overcome the systemic, cellular and intracellular drug delivery barriers faced by peptides. Here, we introduce Man-VIPER, a self-assembling (40-50 nm micelles), pH-sensitive, mannosylated polymeric peptide delivery platform that targets dendritic cells in the lymph nodes, encapsulates peptide antigens at physiological pH, and facilitates endosomal release of antigens at acidic endosomal pH through a conjugated membranolytic peptide melittin. We used d-melittin to improve the safety profile of the formulation without compromising the lytic properties. We evaluated polymers with both releasable (Man-VIPER-R) or non-releasable (Man-VIPER-NR) d-melittin. Both Man-VIPER polymers exhibited superior endosomolysis and antigen cross-presentation compared to non-membranolytic d-melittin-free analogues (Man-AP) in vitro. In vivo, Man-VIPER polymers demonstrated an adjuvanting effect, induced the proliferation of antigen-specific cytotoxic T cells and helper T cells compared to free peptides and Man-AP. Remarkably, antigen delivery with Man-VIPER-NR generated significantly more antigen-specific cytotoxic T cells than Man-VIPER-R in vivo. As our candidate for a therapeutic vaccine, Man-VIPER-NR exerted superior efficacy in a B16F10-OVA tumor model. These results highlight Man-VIPER-NR as a safe and powerful peptide cancer vaccine platform for cancer immunotherapy.

Polymeric nanoparticle-based nanovaccines for cancer immunotherapy

Therapeutic cancer vaccines, which are designed to amplify tumor-specific T cell responses, have been envisioned as one of the most powerful tools for effective cancer immunotherapy. However, increasing the potency, quality and durability of the vaccine response remains a big challenge. In recent years, materials-based delivery systems focusing on the co-delivery of antigens and adjuvants to enhance cancer vaccination therapy have attracted increasing interest. Among various materials, polymeric nanoparticles (NPs) with different physicochemical properties which can incorporate multiple immunological cues are of great interest. In this review, the recent progress in the design and construction of both ex vivo subunit and in situ cancer vaccines using polymeric NPs is summarized. Especially, we will focus on how these NPs improve the adjuvanticity of vaccines. The design principles of polymeric NPs for ex vivo subunit cancer vaccines and in situ cancer vaccination are also discussed. Finally, we want to briefly discuss molecular chaperones in cancer immunity and the applications of our unique self-assembly mixed shell polymeric micelle-based nanochaperones for cancer vaccines.

Bio-Inspired Drug Delivery Systems: From Synthetic Polypeptide Vesicles to Outer Membrane Vesicles

Nanomedicine is a broad field that focuses on the development of nanocarriers to deliver specific drugs to targeted sites. A synthetic polypeptide is a kind of biomaterial composed of repeating amino acid units that are linked by peptide bonds. The multiplied amphiphilicity segment of the polypeptide could assemble to form polypeptide vesicles (PVs) under suitable conditions. Different from polypeptide vesicles, outer membrane vesicles (OMVs) are spherical buds of the outer membrane filled with periplasmic content, which commonly originate from Gram-negative bacteria. Owing to their biodegradability and excellent biocompatibility, both PVs and OMVs have been utilized as carriers in delivering drugs. In this review, we discuss the recent drug delivery research based on PVs and OMVs. These related topics are presented: (1) a brief introduction to the production methods for PVs and OMVs; (2) a thorough explanation of PV- and OMV-related applications in drug delivery including the vesicle design and biological assessment; (3) finally, we conclude with a discussion on perspectives and future challenges related to the drug delivery systems of PVs and OMVs.

Self-assembled nanoparticles: A new platform for revolutionizing therapeutic cancer vaccines

Cancer vaccines have had some success in the past decade. Based on in-depth analysis of tumor antigen genomics, many therapeutic vaccines have already entered clinical trials for multiple cancers, including melanoma, lung cancer, and head and neck squamous cell carcinoma, which have demonstrated impressive tumor immunogenicity and antitumor activity. Recently, vaccines based on self-assembled nanoparticles are being actively developed as cancer treatment, and their feasibility has been confirmed in both mice and humans. In this review, we summarize recent therapeutic cancer vaccines based on self-assembled nanoparticles. We describe the basic ingredients for self-assembled nanoparticles, and how they enhance vaccine immunogenicity. We also discuss the novel design method for self-assembled nanoparticles that pose as a promising delivery platform for cancer vaccines, and the potential in combination with multiple therapeutic approaches.

Locoregional Lymphatic Delivery Systems Using Nanoparticles and Hydrogels for Anticancer Immunotherapy

The lymphatic system has gained significant interest as a target tissue to control cancer progress, which highlights its central role in adaptive immune response. Numerous mechanistic studies have revealed the benefits of nano-sized materials in the transport of various cargos to lymph nodes, overcoming barriers associated with lymphatic physiology. The potential of sustained drug delivery systems in improving the therapeutic index of various immune modulating agents is also being actively discussed. Herein, we aim to discuss design rationales and principles of locoregional lymphatic drug delivery systems for invigorating adaptive immune response for efficient antitumor immunotherapy and provide examples of various advanced nanoparticle- and hydrogel-based formulations.

Mannose in vaccine delivery

Adjuvants and vaccine delivery systems are used widely to improve the efficacy of vaccines. Their primary roles are to protect antigen from degradation and allow its delivery and uptake by antigen presenting cells (APCs). Carbohydrates, including various structures/forms of mannose, have been broadly utilized to target carbohydrate binding receptors on APCs. This review summarizes basic functions of the immune system, focusing on the role of mannose receptors in antigen recognition by APCs. The most popular strategies to produce mannosylated vaccines via conjugation and formulation are presented. The efficacy of mannosylated vaccines is discussed in detail, taking into consideration factors, such as valency and number of mannose in mannose ligands, mannose density, length of spacers, special arrangement of mannose ligands, and routes of administration of mannosylated vaccines. The advantages and disadvantages of mannosylation strategy and future directions in the development of mannosylated vaccines are also debated.

Comprehensive Analysis of Sterol O-Acyltransferase 1 as a Prognostic Biomarker and Its Association With Immune Infiltration in Glioma

Metabolic reprogramming is a hallmark of glioma, and sterol O-acyltransferase 1 (SOAT1) is an essential target for metabolic therapy. However, the prognostic value of SOAT1 and its association with immune infiltration has not been fully elucidated. Using RNA-seq and clinical data of glioma patients from The Cancer Genome Atlas (TCGA), SOAT1 was found to be correlated with poor prognosis in glioma and the advanced malignancy of clinicopathological characteristics. Next, the correlation between SOAT1 expression and tumor-infiltrating immune cells was performed using the single-sample GSEA algorithm, gene expression profiling interactive analysis (GEPIA), and tumor immune estimation resource version 2 (TIMER2.0); it was found that SOAT1 expression was positively correlated with multiple tumor-infiltrating immune cells. To further verify these results, immunofluorescence was conducted on paraffin-embedded glioma specimens, and a positive trend of the correlation between SOAT1 expression and Treg infiltration was observed in this cohort. Finally, differentially expressed gene analysis, and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to explore the biological processes and signaling pathways that SOAT1 may be involved in during glioma pathogenesis. A protein-protein interaction network was established, and co-expression analysis was conducted to investigate the regulatory mechanism of SOAT1 in glioma. To the best of our knowledge, this is the first comprehensive study reporting that SOAT1 may serve as a novel prognostic biomarker associated with immune infiltrates, providing a novel perspective for glioma metabolic therapy.

Tolerance Induced by Antigen-Loaded PLG Nanoparticles Affects the Phenotype and Trafficking of Transgenic CD4+ and CD8+ T Cells

We have shown that PLG nanoparticles loaded with peptide antigen can reduce disease in animal models of autoimmunity and in a phase 1/2a clinical trial in celiac patients. Clarifying the mechanisms by which antigen-loaded nanoparticles establish tolerance is key to further adapting them to clinical use. The mechanisms underlying tolerance induction include the expansion of antigen-specific CD4+ regulatory T cells and sequestration of autoreactive cells in the spleen. In this study, we employed nanoparticles loaded with two model peptides, GP33-41 (a CD8 T cell epitope derived from lymphocytic choriomeningitis virus) and OVA323-339 (a CD4 T cell epitope derived from ovalbumin), to modulate the CD8+ and CD4+ T cells from two transgenic mouse strains, P14 and DO11.10, respectively. Firstly, it was found that the injection of P14 mice with particles bearing the MHC I-restricted GP33-41 peptide resulted in the expansion of CD8+ T cells with a regulatory cell phenotype. This correlated with reduced CD4+ T cell viability in ex vivo co-cultures. Secondly, both nanoparticle types were able to sequester transgenic T cells in secondary lymphoid tissue. Flow cytometric analyses showed a reduction in the surface expression of chemokine receptors. Such an effect was more prominently observed in the CD4+ cells rather than the CD8+ cells.