pH-sensitive polymer-modified liposome-based immunity-inducing system: Effects of inclusion of cationic lipid and CpG-DNA

Nanomaterial-assisted delivery of CpG oligodeoxynucleotides for boosting cancer immunotherapy

Cancer immunotherapy aims to improve immunity to not only eliminate the primary tumor but also inhibit metastasis and recurrence. It is considered an extremely promising therapeutic approach that breaks free from the traditional paradigm of oncological treatment. As the medical community learns more about the immune system's mechanisms that "turn off the brake" and "step on the throttle", there is increasingly successful research on immunomodulators. However, there are still more restrictions than countermeasures with immunotherapy related to immunomodulators, such as low responsiveness and immune-related adverse events that cause multiple adverse reactions. Therefore, medical experts and materials scientists attempted to the efficacy of immunomodulatory treatments through various methods, especially nanomaterial-assisted strategies. CpG oligodeoxynucleotides (CpG) not only act as an adjuvant to promote immune responses, but also induce autophagy. In this review, the enhancement of immunotherapy using nanomaterial-based CpG formulations is systematically elaborated, with a focus on the delivery, protection, synergistic promotion of CpG efficacy by nanomaterials, and selection of the timing of treatment. In addition, we also discuss and prospect the existing problems and future directions of research on nanomaterials in auxiliary CpG therapy.

Adjuvant Delivery Method and Nanoparticle Charge Influence Peptide Amphiphile Micelle Vaccine Bioactivity

Vaccines are an indispensable public health measure that have enabled the eradication, near elimination, and prevention of a variety of pathogens. As research continues and our understanding of immunization strategies develops, subunit vaccines have emerged as exciting alternatives to existing whole vaccine approaches. Unfortunately, subunit vaccines often possess weak antigenicity, requiring delivery devices and adjuvant supplementation to improve their utility. Peptide amphiphile micelles have recently been shown to function as both delivery devices and self-adjuvanting systems that can be readily associated with molecular adjuvants to further improve vaccine-mediated host immunity. While promising, many design rules associated with the plethora of underlying adjustable parameters in the generation of a peptide amphiphile micelle vaccine have yet to be uncovered. This work explores the impact micellar adjuvant complexation method and incorporated antigen type have on their ability to activate dendritic cells and induce antigen specific responses. Interestingly, electrostatic complexation of CpG to micelles resulted in improved in vitro dendritic cell activation over hydrophobic association and antigen|adjuvant co-localization influenced cell-mediated, but not antibody-mediated immune responses. These exciting results complement those previously published to build the framework of a micelle vaccine toolbox that can be leveraged for future disease specific formulations.

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.

Emerging nanoparticle platforms for CpG oligonucleotide delivery

Unmethylated cytosine-phosphate-guanine (CpG) oligodeoxynucleotides (ODNs), which were therapeutic DNA with high immunostimulatory activity, have been applied in widespread applications from basic research to clinics as therapeutic agents for cancer immunotherapy, viral infection, allergic diseases and asthma since their discovery in 1995. The major factors to consider for clinical translation using CpG motifs are the protection of CpG ODNs from DNase degradation and the delivery of CpG ODNs to the Toll-like receptor-9 expressed human B-cells and plasmacytoid dendritic cells. Therefore, great efforts have been devoted to the advances of efficient delivery systems for CpG ODNs. In this review, we outline new horizons and recent developments in this field, providing a comprehensive summary of the nanoparticle-based CpG delivery systems developed to improve the efficacy of CpG-mediated immune responses, including DNA nanostructures, inorganic nanoparticles, polymer nanoparticles, metal-organic-frameworks, lipid-based nanosystems, proteins and peptides, as well as exosomes and cell membrane nanoparticles. Moreover, future challenges in the establishment of CpG delivery systems for immunotherapeutic applications are discussed. We expect that the continuously growing interest in the development of CpG-based immunotherapy will certainly fuel the excitement and stimulation in medicine research.

Nanoparticles in tumor microenvironment remodeling and cancer immunotherapy

Cancer immunotherapy and vaccine development have significantly improved the fight against cancers. Despite these advancements, challenges remain, particularly in the clinical delivery of immunomodulatory compounds. The tumor microenvironment (TME), comprising macrophages, fibroblasts, and immune cells, plays a crucial role in immune response modulation. Nanoparticles, engineered to reshape the TME, have shown promising results in enhancing immunotherapy by facilitating targeted delivery and immune modulation. These nanoparticles can suppress fibroblast activation, promote M1 macrophage polarization, aid dendritic cell maturation, and encourage T cell infiltration. Biomimetic nanoparticles further enhance immunotherapy by increasing the internalization of immunomodulatory agents in immune cells such as dendritic cells. Moreover, exosomes, whether naturally secreted by cells in the body or bioengineered, have been explored to regulate the TME and immune-related cells to affect cancer immunotherapy. Stimuli-responsive nanocarriers, activated by pH, redox, and light conditions, exhibit the potential to accelerate immunotherapy. The co-application of nanoparticles with immune checkpoint inhibitors is an emerging strategy to boost anti-tumor immunity. With their ability to induce long-term immunity, nanoarchitectures are promising structures in vaccine development. This review underscores the critical role of nanoparticles in overcoming current challenges and driving the advancement of cancer immunotherapy and TME modification.

Development of immune cell delivery system using biodegradable injectable polymers for cancer immunotherapy

Immune cell delivery using injectable hydrogel attracts much attention for improving its therapeutic effect. Specifically, dendritic cells (DCs) are the trigger cells for immune responses, and DC vaccines are studied for improving cancer immunotherapy. Hydrogel-assisted cell delivery is expected to enhance the viability of the implanted cells. We recently reported temperature-responsive biodegradable injectable polymer (IP) formulation utilizing poly(ε-caprolactone-co-glycolide)-b-poly(ethylene glycol)(PEG)-b-poly(ε-caprolactone-co-glycolide) (tri-PCG). Tri-PCG-based IP was reported to exhibit immediate sol-to-gel transition in response to temperature increase, in vivo biodegradability, and excellent biocompatibility. In this study, tri-PCG-based IP was applied to DC delivery. IP encapsulated live DCs, and the DCs incorporated ovalbumin (OVA) as a model antigen and CpG-DNA (oligo DNA with adjuvant effect) in IP hydrogel. Results suggested that DCs encapsulated in IP hydrogel internalized OVA and CpG-DNA and DCs were maturated to present antigens to T cells. Moreover, subcutaneously injected tri-PCG-based IP prolonged the retention period of cell accumulation at injected sites. Tri-PCG IP hydrogel could release matured DCs as the degradation of the hydrogel progressed. Tri-PCG IP formulation improved treatment efficacy of OVA transfected mouse lymphoma (E.G7-OVA) tumor. Hence, tri-PCG IP is a promising platform for immune cell delivery.

Small EV-based delivery of CpG ODNs for melanoma postsurgical immunotherapy

Blocking programmed cell death protein 1 (PD-1) is an effective therapeutic strategy for melanoma. However, patients often develop tumor recurrence postoperatively due to the low response rate to the anti-PD-1 antibody (aPD-1). In this study, we developed an in situ sprayable fibrin gel that contains cytosine-guanine oligodeoxynucleotides (CpG ODNs)-modified ovalbumin (OVA) antigen-expressing bone marrow dendritic cell (DC)-derived small extracellular vesicles (DC-sEVs) and aPD-1. CpG ODNs can activate DCs, which have potent immunostimulatory effects, by stimulating both the maturation and activation of tumor-infiltrating dendritic cells (TIDCs) and DCs in tumor-draining lymph nodes (TDLNs). In addition, DC-sEVs can deliver OVA to the same DCs, leading to the specific expression of tumor antigens by antigen-presenting cells (APCs). In brief, the unique synergistic combination of aPD-1 and colocalized delivery of immune adjuvants and tumor antigens enhances antitumor T-cell immunity, not only in the tumor microenvironment (TME) but also in TDLNs. This effectively attenuates local tumor recurrence and metastasis. Our results suggest that dual activation by CpG ODNs prolongs the survival of mice and decreases the recurrence rate in an incomplete tumor resection model, providing a promising approach to prevent B16-F10-OVA melanoma tumor recurrence and metastasis.

Cationic lipid potentiated the adjuvanticity of polysaccharide derivative-modified liposome vaccines

Antigen carriers that can selectively deliver antigens to antigen presenting cells and which can simultaneously activate these cells (adjuvant property) are necessary for efficient cancer immunotherapy or vaccination. Delivery of a model antigen into dendritic cell cytosol has been achieved by pH-responsive polymer-modified liposomes via destabilization of endosomal membranes responding to acidic pH, which impelled antigen-specific cellular immunity. Furthermore, β-glucan-based pH-responsive polysaccharides have shown not only cytosolic antigen delivery performance but also adjuvant property, which further heightened cellular immune responses. Because pH-responsive polysaccharides have anionic carboxy groups, cationic lipid was introduced to liposomes in this study to improve the modification efficiency of pH-responsive polysaccharides and to improve their adjuvanticity and immunity-inducing functions. Introduction of cationic lipids increased the amounts of polysaccharide derivatives on the liposome and increased the cellular association of the liposomes to dendritic cells. Liposomes containing β-glucan-based pH-responsive polysaccharides and cationic lipids increased cytokine production from dendritic cells much more than other polysaccharide derivatives did. Furthermore, through improvement of intra-tumoral immunosuppression and induction of antigen-specific cellular immunity, administering these liposomes impelled tumor suppression even with a small antigen dose. These results suggest that introducing cationic lipids and using pH-responsive polysaccharides having intrinsically adjuvant function are effective for producing liposomal nanovaccines showing strong immunity-inducing function.

Nanomaterials and Their Impact on the Immune System

Nanomaterials have been the focus of intensive development and research in the medical and industrial sectors over the past several decades. Some studies have found that these compounds can have a detrimental impact on living organisms, including their cellular components. Despite the obvious advantages of using nanomaterials in a wide range of applications, there is sometimes skepticism caused by the lack of substantial proof that evaluates potential toxicities. The interactions of nanoparticles (NPs) with cells of the immune system and their biomolecule pathways are an area of interest for researchers. It is possible to modify NPs so that they are not recognized by the immune system or so that they suppress or stimulate the immune system in a targeted manner. In this review, we look at the literature on nanomaterials for immunostimulation and immunosuppression and their impact on how changing the physicochemical features of the particles could alter their interactions with immune cells for the better or for the worse (immunotoxicity). We also look into whether the NPs have a unique or unexpected (but desired) effect on the immune system, and whether the surface grafting of polymers or surface coatings makes stealth nanomaterials that the immune system cannot find and get rid of.

Controlled Synthesis of Dendrite-like Polyglycerols Using Aluminum Complex for Biomedical Applications

This work describes a one-pot synthesis of dendrite-like hyperbranched polyglycerols (HPGs) via a ring-opening multibranching polymerization (ROMBP) process using a bis(5,7-dichloro-2-methyl-8-quinolinolato)methyl aluminum complex (1) as a catalyst and 1,1,1-tris(hydroxymethyl)propane/trimethylol propane (TMP) as an initiator. Single-crystal X-ray diffraction (XRD) analysis was used to elucidate the molecular structure of complex 1. Inverse-gated (IG)¹³C NMR analysis of HPGs showed degree of branching between 0.50 and 0.57. Gel permeation chromatography (GPC) analysis of the HPG polymers provided low, medium, and high-molecular weight (M _n) polymers ranging from 14 to 73 kDa and molecular weight distributions (M _w/M _n) between 1.16 and 1.35. The obtained HPGs exhibited high wettability with water contact angle between 18 and 21° and T _g ranging between -39 and -55 °C. Notably, ancillary ligand-supported aluminum complexes as catalysts for HPG polymerization reactions have not been reported to date. The obtained HPG polymers in the presence of the aluminum complex (1) can be used for various biomedical applications. Here, nanocomposite electrospun fibers were fabricated with synthesized HPG polymer. The nanofibers were subjected to cell culture experiments to evaluate cytocompatibility behavior with L929 and MG63 cells. The cytocompatibility studies of HPG polymer and nanocomposite scaffold showed high cell viability and spreading. The study results concluded, synthesized HPG polymers and composite nanofibers can be used for various biomedical applications.

Toll-like receptor-targeted anti-tumor therapies: Advances and challenges

Toll-like receptors (TLRs) are pattern recognition receptors, originally discovered to stimulate innate immune reactions against microbial infection. TLRs also play essential roles in bridging the innate and adaptive immune system, playing multiple roles in inflammation, autoimmune diseases, and cancer. Thanks to the immune stimulatory potential of TLRs, TLR-targeted strategies in cancer treatment have proved to be able to regulate the tumor microenvironment towards tumoricidal phenotypes. Quantities of pre-clinical studies and clinical trials using TLR-targeted strategies in treating cancer have been initiated, with some drugs already becoming part of standard care. Here we review the structure, ligand, signaling pathways, and expression of TLRs; we then provide an overview of the pre-clinical studies and an updated clinical trial watch targeting each TLR in cancer treatment; and finally, we discuss the challenges and prospects of TLR-targeted therapy.

Current advances in the use of exosomes, liposomes, and bioengineered hybrid nanovesicles in cancer detection and therapy

Three major approaches of cancer therapy can be enunciated as delivery of biotherapeutics, tumor image analysis, and immunotherapy. Liposomes, artificial fat bubbles, are long known for their capacity to encapsulate a diverse range of bioactive molecules and release the payload in a sustained, stimuli-responsive manner. They have already been widely explored as a delivery vehicle for therapeutic drugs as well as imaging agents. They are also extensively being used in cancer immunotherapy. On the other hand, exosomes are naturally occurring nanosized extracellular vesicles that serve an important role in cell-cell communication. Importantly, the exosomes also have proven their capability to carry an array of active pharmaceuticals and diagnostic molecules to the tumor cells. Exosomes, being enriched with tumor antigens, have numerous immunomodulatory effects. Much to our intrigue, in recent times, efforts have been directed toward developing smart, bioengineered, exosome-liposome hybrid nanovesicles, which are augmented by the benefits of both vesicular systems. This review attempts to summarize the contemporary developments in the use of exosome and liposome toward cancer diagnosis, therapy, as a vehicle for drug delivery, diagnostic carrier for tumor imaging, and cancer immunotherapy. We shall also briefly reflect upon the recent advancements of the exosome-liposome hybrids in cancer therapy. Finally, we put forward future directions for the use of exosome/liposome and/or hybrid nanocarriers for accurate diagnosis and personalized therapies for cancers.

Chemopreventive Potential of Dietary Nanonutraceuticals for Prostate Cancer: An Extensive Review

There are more than two hundred fifty different types of cancers, that are diagnosed around the world. Prostate cancer is one of the suspicious type of cancer spreading very fast around the world, it is reported that in 2018, 29430 patients died of prostate cancer in the United State of America (USA), and hence it is expected that one out of nine men diagnosed with this severe disease during their lives. Medical science has identified cancer at several stages and indicated genes mutations involved in the cancer cell progressions. Genetic implications have been studied extensively in cancer cell growth. So most efficacious drug for prostate cancer is highly required just like other severe diseases for men. So nutraceutical companies are playing major role to manage cancer disease by the recommendation of best natural products around the world, most of these natural products are isolated from plant and mushrooms because they contain several chemoprotective agents, which could reduce the chances of development of cancer and protect the cells for further progression. Some nutraceutical supplements might activate the cytotoxic chemotherapeutic effects by the mechanism of cell cycle arrest, cell differentiation procedures and changes in the redox states, but in other, it also elevate the levels of effectiveness of chemotherapeutic mechanism and in results, cancer cell becomes less reactive to chemotherapy. In this review, we have highlighted the prostate cancer and importance of nutraceuticals for the control and management of prostate cancer, and the significance of nutraceuticals to cancer patients during chemotherapy.

Therapeutic Cancer Vaccines—Antigen Discovery and Adjuvant Delivery Platforms

For decades, vaccines have played a significant role in protecting public and personal health against infectious diseases and proved their great potential in battling cancers as well. This review focused on the current progress of therapeutic subunit vaccines for cancer immunotherapy. Antigens and adjuvants are key components of vaccine formulations. We summarized several classes of tumor antigens and bioinformatic approaches of identification of tumor neoantigens. Pattern recognition receptor (PRR)-targeting adjuvants and their targeted delivery platforms have been extensively discussed. In addition, we emphasized the interplay between multiple adjuvants and their combined delivery for cancer immunotherapy.

Co-delivery of Interleukin-12 and Doxorubicin Loaded Nano-delivery System for Enhanced Immunotherapy with Polarization toward M1-type Macrophages

Chemo-immunotherapy has gained increasing attention as one of the most promising combination therapy strategies to battle cancer. In this study, the therapeutic nanoparticles (TNPs) co-delivering doxorubicin (DOX) and IL-12 (IL-12) were developed for chemo-immunotherapy combination therapy on liver cancer. TNPs were synthesized based on the ionic interactions between cationic chitosan (Ch) and anionic poly-(glutamic acid) (PGA). DOX and IL-12 loaded in TNPs presented prolonged circulation in blood, efficient accumulation in tumors, and internalization in tumor cells. After that, DOX and IL-12 were co-released in the tumor microenvironment. The locally responsive property of TNPs could subsequently re-educate macrophages. More significantly, TNPs with no obvious side effects can remarkably inhibit the H22 tumor growth in vivo. A low dosage of loaded IL-12 in TNPs can effectively polarize macrophages toward the M1 phenotype to reduce tumor burden, further enhancing the antitumor efficacy. Our results suggest that the self-stabilized TNPs could be a secure and effective drug carrier for intravenous administration when deprived of protective agents.

Construction of nanocarriers based on nucleic acids and their application in nanobiology delivery systems

In recent years, nanocarriers based on nucleic acids (NCNAs) have emerged as powerful and novel nanocarriers that are able to meet the demand for cancer cell-specific targeting. Functional dynamics analysis revealed good biocompatibility, low toxicity, and programmable structures, and their advantages include controllable size and modifiability. The development of novel hybrids has focused on the distinct roles of biosensing, drug and gene delivery, vaccine transport, photosensitization, counteracting drug resistance and functioning as carriers and logic gates. This review is divided into three parts: (1) DNA nanocarriers, (2) RNA nanocarriers, and (3) DNA/RNA hybrid nanocarriers and their biological applications. We also provide perspectives on possible future directions for growth in this field.

Development of nanotechnology-mediated precision radiotherapy for anti-metastasis and radioprotection

Radiotherapy (RT), including external beam RT and internal radiation therapy, uses high-energy ionizing radiation to kill tumor cells.

Preparation of hyaluronic acid-coated polymeric micelles for nasal vaccine delivery

Hyaluronic acid (HA)-coated biodegradable polymeric micelles were developed as nanoparticulate vaccine delivery systems to establish an effective nasal vaccine. We previously reported HA-coated micelles prepared by forming a polyion complex...

Stimuli-Responsive Polymeric Nanomaterials for the Delivery of Immunotherapy Moieties: Antigens, Adjuvants and Agonists

Immunotherapy has been investigated for decades, and it has provided promising results in preclinical studies. The most important issue that hinders researchers from advancing to clinical studies is the delivery system for immunotherapy agents, such as antigens, adjuvants and agonists, and the activation of these agents at the tumour site. Polymers are among the most versatile materials for a variety of treatments and diagnostics, and some polymers are reactive to either endogenous or exogenous stimuli. Utilizing this advantage, researchers have been developing novel and effective polymeric nanomaterials that can deliver immunotherapeutic moieties. In this review, we summarized recent works on stimuli-responsive polymeric nanomaterials that deliver antigens, adjuvants and agonists to tumours for immunotherapy purposes.

Biomembrane-based nanostructures for cancer targeting and therapy: From synthetic liposomes to natural biomembranes and membrane-vesicles

The translational success of liposomes in chemotherapeutics has already demonstrated the great potential of biomembrane-based nanostructure in effective drug delivery. Meanwhile, increasing efforts are being dedicated to the application of naturally derived lipid membranes, including cellular membranes and extracellular vesicles in anti-cancer therapies. While synthetic liposomes support superior multifunctional flexibility, natural biomembrane materials possess interesting biomimetic properties and can also be further engineered for intelligent design. Despite being remarkably different from each other in production and composition, the phospholipid bilayer structure in common allows liposomes, cell membrane-derived nanomaterials, and extracellular vesicles to be modified, functionalized, and exploited in many similar manners against challenges posed by tumor-targeted drug delivery. This review will summarize the recent advancements in engineering the membrane-derived nanostructures with "intelligent" modules to respond, regulate, and target tumor cells and the microenvironment to fight against malignancy. We will also discuss perspectives of combining engineered functionalities with naturally occurring activity for enhanced cancer therapy.

Bifunctional lipids in tumor vaccines: An outstanding delivery carrier and promising immune stimulator

Cancer is still a major threat for human life, and the cancer immunotherapy can be more optimized to prolong life. However, the effect of immunotherapy is not encouraging. In order to achieve outstanding immune effect, it is necessary to strengthen antigens uptake of antigen presenting cells. Adjuvants were added to vaccines to achieve this purpose, which could be divided into two types: as an immunostimulatory molecule, the innate immunities of the body were triggered; or as a delivery carrier, and antigens were cross-delivery through the "cytoplasmic pathway" and released at a specific location. This paper reviewed the relevant research status of tumor vaccine immune adjuvants in recent years. Among the review, the function, combination strategies and derivatives of lipid A were discussed in detail. In addition, some suggestions on the existing problems and research direction of lipids as tumor vaccine adjuvants were put forward.

pH-Sensitive branched β-glucan-modified liposomes for activation of antigen presenting cells and induction of antitumor immunity

Induction of cellular immunity is important for effective cancer immunotherapy. Although various antigen carriers for cancer immunotherapy have been developed to date, balancing efficient antigen delivery to antigen presenting cells (APCs) and their activation via innate immune receptors, both of which are crucially important for the induction of strong cellular immunity, remains challenging. For this study, branched β-glucan was selected as an intrinsically immunity-stimulating and biocompatible material. It was engineered to develop multifunctional liposomal cancer vaccines capable of efficient interactions with APCs and subsequent activation of the cells. Hydroxy groups of branched β-glucan (Aquaβ) were modified with 3-methylglutaric acid ester and decyl groups, respectively, to provide pH-sensitivity and anchoring capability to the liposomal membrane. The modification efficiency of Aquaβ derivatives to the liposomes was significantly high compared with linear β-glucan (curdlan) derivatives. Aquaβ derivative-modified liposomes released their contents in response to weakly acidic pH. As a model antigenic protein, ovalbumin (OVA)-loaded liposomes modified with Aquaβ derivatives interacted efficiently with dendritic cells, and induced inflammatory cytokine secretion from the cells. Subcutaneous administration of Aquaβ derivative-modified liposomes suppressed the growth of the E.G7-OVA tumor significantly compared with curdlan derivative-modified liposomes. Aquaβ derivative-modified liposomes induced the increase of CD8⁺ T cells, and polarized macrophages to the antitumor M1-phenotype within the tumor microenvironment. Therefore, pH-sensitive Aquaβ derivatives can be promising materials for liposomal antigen delivery systems to induce antitumor immune responses efficiently.

Dynamic nanoassembly-based drug delivery system (DNDDS): Learning from nature

Dynamic nanoassembly-based drug delivery system (DNDDS) has evolved from being a mere curiosity to emerging as a promising strategy for high-performance diagnosis and/or therapy of various diseases. However, dynamic nano-bio interaction between DNDDS and biological systems remains poorly understood, which can be critical for precise spatiotemporal and functional control of DNDDS in vivo. To deepen the understanding for fine control over DNDDS, we aim to explore natural systems as the root of inspiration for researchers from various fields. This review highlights ingenious designs, nano-bio interactions, and controllable functionalities of state-of-the-art DNDDS under endogenous or exogenous stimuli, by learning from nature at the molecular, subcellular, and cellular levels. Furthermore, the assembly strategies and response mechanisms of tailor-made DNDDS based on the characteristics of various diseased microenvironments are intensively discussed. Finally, the current challenges and future perspectives of DNDDS are briefly commented.

Recent advances in liposome formulations for breast cancer therapeutics

Among many nanoparticle-based delivery platforms, liposomes have been particularly successful with many formulations passed into clinical applications. They are well-established and effective gene and/or drug delivery systems, widely used in cancer therapy including breast cancer. In this review we discuss liposome design with the targeting feature and triggering functions. We also summarise the recent progress (since 2014) in liposome-based therapeutics for breast cancer including chemotherapy and gene therapy. We finally identify some challenges on the liposome technology development for the future clinical translation.

Harnessing the physicochemical properties of DNA as a multifunctional biomaterial for biomedical and other applications

The biological purpose of DNA is to store, replicate, and convey genetic information in cells. Progress in molecular genetics have led to its widespread applications in gene editing, gene therapy, and forensic science. However, in addition to its role as a genetic material, DNA has also emerged as a nongenetic, generic material for diverse biomedical applications. DNA is essentially a natural biopolymer that can be precisely programed by simple chemical modifications to construct materials with desired mechanical, biological, and structural properties. This review critically deciphers the chemical tools and strategies that are currently being employed to harness the nongenetic functions of DNA. Here, the primary product of interest has been crosslinked, hydrated polymers, or hydrogels. State-of-the-art applications of macroscopic, DNA-based hydrogels in the fields of environment, electrochemistry, biologics delivery, and regenerative therapy have been extensively reviewed. Additionally, the review encompasses the status of DNA as a clinically and commercially viable material and provides insight into future possibilities.

Development of CpG oligodeoxynucleotide TLR9 agonists in anti-cancer therapy

INTRODUCTION

Toll-like receptor-9(TLR9) can recognize the foreign unmethylated CpG DNA, and thus intrigue a strong Th1 response which plays a crucial role in the innate and adaptive immune responses. To date, CpG oligodeoxynucleotide (ODN)-based TLR9 agonists have undergone four generations. Each generations' breakthroughs in immune activation, safety profiles and pharmacokinetic properties were confirmed by both preclinical and clinical studies.

AREAS COVERED

We reviewed the development and major clinical trials of TLR9 agonists and summarized the optimization strategies of each generation. The applications, limitations and prospects of TLR9 agonists in cancer immunotherapy are also discussed.

EXPERT OPINION

Clinical trials of CpG ODN TLR9 agonists as a single agent demonstrated insufficient efficacy to reverse the immunosuppressive status of majority of patients with high tumor burden. Therefore, more efforts are now been carried out in combination with chemotherapy, radiotherapy and immunotherapy maintenance therapy as well as vaccine adjuvant. Importantly, the synergistic and complementary effect of TLR9 agonists and tumor immune checkpoint inhibitor therapy is expected to exert greater potential. On the other hand, the double-edged sword effect of TLR9 activation in tumor and toxic effect reported in combination therapies should be noted and further studies required.

Recent Advancements in Nanomedicine for 'Cold' Tumor Immunotherapy

Although current anticancer immunotherapies using immune checkpoint inhibitors (ICIs) have been reported with a high clinical success rate, numerous patients still bear 'cold' tumors with insufficient T cell infiltration and low immunogenicity, responding poorly to ICI therapy. Considering the advancements in precision medicine, in-depth mechanism studies on the tumor immune microenvironment (TIME) among cold tumors are required to improve the treatment for these patients. Nanomedicine has emerged as a promising drug delivery system in anticancer immunotherapy, activates immune function, modulates the TIME, and has been applied in combination with other anticancer therapeutic strategies. This review initially summarizes the mechanisms underlying immunosuppressive TIME in cold tumors and addresses the recent advancements in nanotechnology for cold TIME reversal-based therapies, as well as a brief talk about the feasibility of clinical translation.

Effects on immunization of the physicochemical parameters of particles as vaccine carriers

Vaccination has milestone significance for the prophylactic and complete elimination of infectious diseases. However, combating malignant infectious diseases, such as Ebola or HIV, remains a challenge. It is necessary to explore novel technologies to facilitate the immune profile of vaccines. Particles exhibit a remarkable ability to modulate sophisticated immunity because of their intrinsic adjuvanticity or codelivery with immunostimulatory molecules. Recently, particles have been broadly investigated as carriers for vaccine delivery. Their physicochemical parameters (e.g., size, shape, and surface chemistry) significantly influence their in vivo fate and subsequent immunization effect. Herein, we highlight several types of particulate carrier used in the delivery of vaccines. We also examine how to engineer the physical and chemical characteristics of particulate adjuvants to make them robust candidates for a versatile vaccine delivery platform.

Nanocarrier-delivered small interfering RNA for chemoresistant ovarian cancer therapy

Ovarian cancer is the fifth leading cause of cancer-related death in women in the United States. Because success in early screening is limited, and most patients with advanced disease develop resistance to multiple treatment modalities, the overall prognosis of ovarian cancer is poor. Despite the revolutionary role of surgery and chemotherapy in curing ovarian cancer, recurrence remains a major challenge in treatment. Thus, improving our understanding of the pathogenesis of ovarian cancer is essential for developing more effective treatments. In this review, we analyze the underlying molecular mechanisms leading to chemotherapy resistance. We discuss the clinical benefits and potential challenges of using nanocarrier-delivered small interfering RNA to treat chemotherapy-resistant ovarian cancer. We aim to elicit collaborative studies on nanocarrier-delivered small interfering RNA to improve the long-term survival rate and quality of life of patients with ovarian cancer. This article is categorized under: RNA Methods > RNA Nanotechnology Regulatory RNAs/RNAi/Riboswitches > RNAi: Mechanisms of Action.

Polymeric Nanoparticle-Based Vaccine Adjuvants and Delivery Vehicles

As vaccine formulations have progressed from including live or attenuated strains of pathogenic components for enhanced safety, developing new adjuvants to more effectively generate adaptive immune responses has become necessary. In this context, polymeric nanoparticles have emerged as a promising platform with multiple advantages, including the dual capability of adjuvant and delivery vehicle, administration via multiple routes, induction of rapid and long-lived immunity, greater shelf-life at elevated temperatures, and enhanced patient compliance. This comprehensive review describes advances in nanoparticle-based vaccines (i.e., nanovaccines) with a particular focus on polymeric particles as adjuvants and delivery vehicles. Examples of the nanovaccine approach in respiratory infections, biodefense, and cancer are discussed.

Nanoparticles as Smart Carriers for Enhanced Cancer Immunotherapy

Cancer immunotherapy has emerged as a promising strategy for the treatment of many forms of cancer by stimulating body's own immune system. This therapy not only eradicates tumor cells by inducing strong anti-tumor immune response but also prevent their recurrence. The clinical cancer immunotherapy faces some insurmountable challenges including high immune-mediated toxicity, lack of effective and targeted delivery of cancer antigens to immune cells and off-target side effects. However, nanotechnology offers some solutions to overcome those limitations, and thus can potentiate the efficacy of immunotherapy. This review focuses on the advancement of nanoparticle-mediated delivery of immunostimulating agents for efficient cancer immunotherapy. Here we have outlined the use of the immunostimulatory nanoparticles as a smart carrier for effective delivery of cancer antigens and adjuvants, type of interactions between nanoparticles and the antigen/adjuvant as well as the factors controlling the interaction between nanoparticles and the receptors on antigen presenting cells. Besides, the role of nanoparticles in targeting/activating immune cells and modulating the immunosuppressive tumor microenvironment has also been discussed extensively. Finally, we have summarized some theranostic applications of the immunomodulatory nanomaterials in treating cancers based on the earlier published reports.

Size-Dependent Antibacterial Immunity of Staphylococcus aureus Protoplast-Derived Particulate Vaccines

Background

Vaccination provides a viable alternative to antibiotics for the treatment of drug-resistant bacterial infection. Bacterial protoplasts have gained much attention for a new generation vaccine due to depleting toxic outer wall components.

Purpose

The objective of this study was to reveal the effects of bacterial protoplast-derived nanovesicles (PDNVs) size on antibacterial immunity.

Methods

Herein, we prepared bacterial PDNVs with different sizes by removing the cell wall of Staphylococcus aureus (S. aureus) to generate multi-antigen nanovaccines. Furthermore, we investigated the ability of PDNVs in different sizes to activate dendritic cells (DCs) and trigger humoral and cellular immune responses in vivo.

Results

We obtained particles of ∼200 nm, 400 nm, and 700 nm diameters and found that all the PDNVs readily induce efficient maturation of DCs in the draining lymph nodes of the vaccinated mice. Dramatically, the activation of DCs was increased with decreasing particle sizes. In addition, vaccination with PDNVs generated elevated expression levels of specific antibody and the production of INF-γ, especially the smaller ones, indicating the capability of inducing strong humoral immunity and Th1 biased cell responses against the source bacteria.

Conclusion

These observed results provide evidence for size-dependent orchestration of immune responses of PDNVs and help to rationally design and develop effective antibacterial vaccines.

Recombination Monophosphoryl Lipid A-Derived Vacosome for the Development of Preventive Cancer Vaccines

Recently, there has been an increasing interest for utilizing the host immune system to fight against cancer. Moreover, cancer vaccines, which can stimulate the host immune system to respond to cancer in the long term, are being investigated as a promising approach to induce tumor-specific immunity. In this work, we prepared an effective cancer vaccine (denoted as "vacosome") by reconstructing the cancer cell membrane, monophosphoryl lipid A as a toll-like receptor 4 agonist, and egg phosphatidylcholine. The vacosome triggered and enhanced bone marrow dendritic cell maturation as well as stimulated the antitumor response against breast cancer 4T1 cells in vitro. Furthermore, an immune memory was established in BALB/c mice after three-time preimmunization with the vacosome. After that, the immunized mice showed inhibited tumor growth and prolonged survival period (longer than 50 days). Overall, our results demonstrate that the vacosome can be a potential candidate for clinical translation as a cancer vaccine.

Chemical Strategies to Boost Cancer Vaccines

Personalized cancer vaccines (PCVs) are reinvigorating vaccine strategies in cancer immunotherapy. In contrast to adoptive T-cell therapy and checkpoint blockade, the PCV strategy modulates the innate and adaptive immune systems with broader activation to redeploy antitumor immunity with individualized tumor-specific antigens (neoantigens). Following a sequential scheme of tumor biopsy, mutation analysis, and epitope prediction, the administration of neoantigens with synthetic long peptide (SLP) or mRNA formulations dramatically improves the population and activity of antigen-specific CD4+ and CD8+ T cells. Despite the promising prospect of PCVs, there is still great potential for optimizing prevaccination procedures and vaccine potency. In particular, the arduous development of tumor-associated antigen (TAA)-based vaccines provides valuable experience and rational principles for augmenting vaccine potency which is expected to advance PCV through the design of adjuvants, delivery systems, and immunosuppressive tumor microenvironment (TME) reversion since current personalized vaccination simply admixes antigens with adjuvants. Considering the broader application of TAA-based vaccine design, these two strategies complement each other and can lead to both personalized and universal therapeutic methods. Chemical strategies provide vast opportunities for (1) exploring novel adjuvants, including synthetic molecules and materials with optimizable activity, (2) constructing efficient and precise delivery systems to avoid systemic diffusion, improve biosafety, target secondary lymphoid organs, and enhance antigen presentation, and (3) combining bioengineering methods to innovate improvements in conventional vaccination, "smartly" re-educate the TME, and modulate antitumor immunity. As chemical strategies have proven versatility, reliability, and universality in the design of T cell- and B cell-based antitumor vaccines, the union of such numerous chemical methods in vaccine construction is expected to provide new vigor and vitality in cancer treatment.

Nanoparticle cancer vaccines: Design considerations and recent advances

Vaccines therapeutics manipulate host's immune system and have broad potential for cancer prevention and treatment. However, due to poor immunogenicity and limited safety, fewer cancer vaccines have been successful in clinical trials. Over the past decades, nanotechnology has been exploited to deliver cancer vaccines, eliciting long-lasting and effective immune responses. Compared to traditional vaccines, cancer vaccines delivered by nanomaterials can be tuned towards desired immune profiles by (1) optimizing the physicochemical properties of the nanomaterial carriers, (2) modifying the nanomaterials with targeting molecules, or (3) co-encapsulating with immunostimulators. In order to develop vaccines with desired immunogenicity, a thorough understanding of parameters that affect immune responses is required. Herein, we discussed the effects of physicochemical properties on antigen presentation and immune response, including but not limited to size, particle rigidity, intrinsic immunogenicity. Furthermore, we provided a detailed overview of recent preclinical and clinical advances in nanotechnology for cancer vaccines, and considerations for future directions in advancing the vaccine platform to widespread anti-cancer applications.

Engineering nanoparticulate vaccines for enhancing antigen cross-presentation

Efficient cross-presentation is pivotal for vaccination against cancer and infection by intracellular virus and bacteria. Recently, various types of nanoparticle vaccines have been developed and investigated for efficiently and specifically improving cross-presentation and CD8⁺ T cell priming. In this review, we will summarize the known intracellular pathways involved in cross-presentation, and focus on several nanoparticle strategies that have been reported for enhancing cross-presentation, including designing multifunctional nano-vaccines for increasing endosomal escape, designing nano-vaccines that can target lymph nodes to improve antigen uptake by lymph node resident CD8α⁺ dendritic cells, and co-delivering immune modulators for upregulating cross-presentation related intracellular components. We will also briefly discuss the future prospects of cross-presentation based nano-vaccine strategy for curing diseases.

Programmable Delivery of Immune Adjuvant to Tumor-Infiltrating Dendritic Cells for Cancer Immunotherapy

Tumor-infiltrating dendritic cells (TIDCs) are mostly immature and immunosuppressive, usually mediating immune inhibition. The utilization of cytosine-guanine oligodeoxynucleotides (CpG ODNs) to stimulate the activation of TIDCs has been demonstrated to be effective for improving antitumor immunity. However, a series of biological barriers has limited the efficacy of previous nanocarriers for delivering CpG to TIDCs. Herein, we developed a dual-sensitive dendrimer cluster-based nanoadjuvant for delivering CpG ODNs into TIDCs. We show that the tumor acidity triggers the rapid release of CpG conjugated polyamidoamine (PAMAM) dendrimers from the nanoadjuvant, thus facilitating its perfusion deep into tumors and phagocytosis by TIDCs. Thereafter, the reductive condition of the endolysosomes led to the subsequent release of CpG, which promotes the DCs activation and enhances antitumor immunotherapies. Programmable delivery of immune adjuvant efficiently overcomes the barriers for targeted delivery to TIDCs and provides a promising strategy for improving cancer immunotherapy.

Nanomedicine-mediated alteration of the pharmacokinetic profile of small molecule cancer immunotherapeutics

The advent of immunotherapy is a game changer in cancer therapy with monoclonal antibody- and T cell-based therapeutics being the current flagships. Small molecule immunotherapeutics might offer advantages over the biological drugs in terms of complexity, tissue penetration, manufacturing cost, stability, and shelf life. However, small molecule drugs are prone to rapid systemic distribution, which might induce severe off-target side effects. Nanotechnology could aid in the formulation of the drug molecules to improve their delivery to specific immune cell subsets. In this review we summarize the current efforts in changing the pharmacokinetic profile of small molecule immunotherapeutics with a strong focus on Toll-like receptor agonists. In addition, we give our vision on limitations and future pathways in the route of nanomedicine to the clinical practice.

Advanced biomaterials for cancer immunotherapy

Immunotherapy, as a powerful strategy for cancer treatment, has achieved tremendous efficacy in clinical trials. Despite these advancements, there is much to do in terms of enhancing therapeutic benefits and decreasing the side effects of cancer immunotherapy. Advanced nanobiomaterials, including liposomes, polymers, and silica, play a vital role in the codelivery of drugs and immunomodulators. These nanobiomaterial-based delivery systems could effectively promote antitumor immune responses and simultaneously reduce toxic adverse effects. Furthermore, nanobiomaterials may also combine with each other or with traditional drugs via different mechanisms, thus giving rise to more accurate and efficient tumor treatment. Here, an overview of the latest advancement in these nanobiomaterials used for cancer immunotherapy is given, describing outstanding systems, including lipid-based nanoparticles, polymer-based scaffolds or micelles, inorganic nanosystems, and others.

Engineering nanoparticles to reprogram radiotherapy and immunotherapy: recent advances and future challenges

Nanoparticles (NPs) have been increasingly studied for radiosensitization. The principle of NPs radio-enhancement is to use high-atomic number NPs (e.g. gold, hafnium, bismuth and gadolinium) or deliver radiosensitizing substances, such as cisplatin and selenium. Nowadays, cancer immunotherapy is emerged as a promising treatment and immune checkpoint regulation has a potential property to improve clinical outcomes in cancer immunotherapy. Furthermore, NPs have been served as an ideal platform for immunomodulator system delivery. Owing to enhanced permeability and retention (EPR) effect, modified-NPs increase the targeting and retention of antibodies in target cells. The purpose of this review is to highlight the latest progress of nanotechnology in radiotherapy (RT) and immunotherapy, as well as combining these three strategies in cancer treatment. Overall, nanomedicine as an effective strategy for RT can significantly enhance the outcome of immunotherapy response and might be beneficial for clinical transformation.

Delivery of nucleic acid therapeutics for cancer immunotherapy

Cancer immunotherapy has shown great potential as witnessed by an increasing number of immuno-oncology drug approvals in the past few years. Meanwhile, the field of nucleic acid therapeutics has made significant advancement. Nucleic acid therapeutics, such as plasmids, antisense oligonucleotides (ASO), small interfering RNA (siRNA) and microRNA, messenger RNA (mRNA), immunomodulatory DNA/RNA, and gene-editing guide RNA (gRNA) are attractive due to their versatile abilities to alter the expression of target endogenous genes or even synthetic genes, and modulate the immune responses. These abilities can play vital roles in the development of novel immunotherapy strategies. However, limited by the intrinsic physicochemical properties such as negative charges, hydrophilicity, as well as susceptibility to enzymatic degradation, the delivery of nucleic acid therapeutics faces multiple challenges. It is therefore pivotal to develop drug delivery systems that can carry, protect, and specifically deliver and release nucleic acid therapeutics to target tissues and cells. In this review, we attempted to summarize recent advances in nucleic acid therapeutics and the delivery systems for these therapeutics in cancer immunotherapy.

Development of functional liposomes by modification of stimuli-responsive materials and their biomedical applications

Liposomes are a promising nanocarrier for drug delivery because of their biocompatibility and the encapsulation capacity of drugs. Liposomes can be functionalized easily by introduction of functional materials such as stimulus-responsive materials. Temperature-responsive liposomes and pH-responsive liposomes are representative stimulus-responsive liposomes that can deliver drugs to locally heated target tissues and intracellular organelles. Here, temperature-responsive liposomes for the selective release of cargo and pH-responsive liposomes for the induction of antigen-specific immunity are overviewed. Temperature-responsive polymer-modified liposomes immediately released drugs in response to heating, which achieved selective drug release at a tumour after topical heating of tumour-bearing mice. Introduction of MR-detectable molecules enabled the tracing of liposome accumulation into target sites to optimize the heating timing. These liposomes can also be combined with magnetic nanoparticles or carbon nanomaterials to attain magnetic field-responsive, electric field-responsive and light-responsive properties to support on-demand drug release or control of biological reactions using these external stimuli. pH-Responsive liposomes were produced by modification of poly(carboxylic acid) derivatives or by pH-responsive amphiphiles. These liposomes delivered antigenic proteins into the cytosol of antigen presenting cells, which induced cross-presentation and antigen-specific cellular immunity. Adjuvant molecules or bioactive polysaccharide-based pH-responsive polymers improved their immunity-inducing effect further, leading to tumour regression in tumour-bearing mice. Precise design and control of the structures of stimulus-responsive materials and combination with functional materials are expected to create novel methodologies to control biological functions and to produce highly potent liposomal drugs that can achieve selective release of bioactive molecules.