Nanoparticle-based strategies for cancer immunotherapy and immunodiagnostics

Varying the hydrophobic core composition of polymeric nanoparticles affects NLRP3 inflammasome activation

Understanding the interactions of nanoparticle carriers with innate immune cells is crucial for informing the design and efficacy of future nano-immunotherapies. An intriguing aspect of their interaction with the immune system has recently emerged, i.e., their ability to activate the NLRP3 inflammasome, a key component of the innate immune response. While the effect of the surface properties of nanoparticles has been extensively investigated in the context of nanoparticle-immune cell interactions, the influence of core composition remains largely unexplored, particularly regarding its impact on inflammasome activation. To shed light on these interactions, we developed a library of supramolecular polymer nanoparticles (SNPs) with different core compositions, varying their hydrophobic quotient by virtue of the side chain length and the repeating units in the polymer construct. The impact of modulating SNP core hydrophobic properties was investigated in macrophages by evaluating their cellular internalization, cytokine release, lysosomal rupture-calcium signaling, calcium flux-mitochondrial ROS production and their ability to activate the NLRP3 inflammasome, providing mechanistic insights into inflammasome activation. We established a direct correlation between increasing the side chain length of the polymer construct, thereby increasing the core hydrophobicity of SNPs and enhanced NLRP3 complex formation, as indicated by ASC speck imaging analysis and the elevated 1L-1β expression. Furthermore, the results demonstrated that the inflammasome signaling cascades and kinetics varied based on the SNP's hydrophobic side chain length and repeating units. Specifically, the nanoparticle with the longest alkyl side chain effectuated NLRP3 activation preferentially through the mitochondrial damage pathway. In vivo evaluation of SNPs in C57BL/6 mice confirmed elevated proinflammatory cytokines, notably with the SNP having the longest C12-alkyl side chain. This confirms that the higher core hydrophobicity composition of the SNP results in inflammasome activation in vivo. In summary, this study established SNP core composition as a novel nanoparticle-associated molecular pattern (NAMP) responsible for NLRP3 inflammasome activation, shedding light on intricate cellular pathways for informed nanoparticle design in immunotherapy and vaccine applications.

Cancer Vaccines Designed Based the Nanoparticle and Tumor Cells for the Treatment of Tumors: A Perspective

Cancer vaccines based on tumor cell components have shown promising results in animal and clinical studies. The vaccine system contains abundant tumor antigen components, which can activate the immune system by antigens. However, their efficacy has been limited by the inability of antigens delivery, which are the core components of vaccines, further fail to be presented and activation of effective cells. Nanotechnology offers a novel platform to enhance the immunogenicity of tumor-associated antigens and deliver them to antigen-presenting cells (APCs) more efficiently. In addition, nanotreatment of tumor cells derivate active ingredients could also help improve the effectiveness of cancer vaccines. In this review, we summarize recent advances in the development of cancer vaccines by the combination of nanotechnology and tumor-based ingredients, including liposomes, polymeric nanoparticles, metallic nanoparticles, virus-like particles and tumor cells membrane, tumor lysate, and specific tumor antigens. These nanovaccines have been designed to increase antigen uptake, prolong antigen presentation, and modulate immune responses through codelivery of immunostimulatory agents. We also further discuss challenges and opportunities in the clinical translation of these nanovaccines.

Nanoparticle-Based Immunotherapy for Reversing T-Cell Exhaustion

T-cell exhaustion refers to a state of T-cell dysfunction commonly observed in chronic infections and cancer. Immune checkpoint molecules blockading using PD-1 and TIM-3 antibodies have shown promising results in reversing exhaustion, but this approach has several limitations. The treatment of T-cell exhaustion is still facing great challenges, making it imperative to explore new therapeutic strategies. With the development of nanotechnology, nanoparticles have successfully been applied as drug carriers and delivery systems in the treatment of cancer and infectious diseases. Furthermore, nanoparticle-based immunotherapy has emerged as a crucial approach to reverse exhaustion. Here, we have compiled the latest advances in T-cell exhaustion, with a particular focus on the characteristics of exhaustion that can be targeted. Additionally, the emerging nanoparticle-based delivery systems were also reviewed. Moreover, we have discussed, in detail, nanoparticle-based immunotherapies that aim to reverse exhaustion, including targeting immune checkpoint blockades, remodeling the tumor microenvironment, and targeting the metabolism of exhausted T cells, etc. These data could aid in comprehending the immunopathogenesis of exhaustion and accomplishing the objective of preventing and treating chronic diseases or cancer.

Poly-γ-glutamic acid nanoparticles as adjuvant and antigen carrier system for cancer vaccination

Vaccination is an innovative strategy for cancer treatment by leveraging various components of the patients' immunity to boost an anti-tumor immune response. Rationally designed nanoparticles are well suited to maximize cancer vaccination by the inclusion of immune stimulatory adjuvants. Also, nanoparticles might control the pharmacokinetics and destination of the immune potentiating compounds. Poly-γ-glutamic acid (γ-PGA) based nanoparticles (NPs), which have a natural origin, can be easily taken up by dendritic cells (DCs), which leads to the secretion of cytokines which ameliorates the stimulation capacity of T cells. The intrinsic adjuvant properties and antigen carrier properties of γ-PGA NPs have been the focus of recent investigations as they can modulate the tumor microenvironment, can contribute to systemic anti-tumor immunity and subsequently inhibit tumor growth. This review provides a comprehensive overview on the potential of γ-PGA NPs as antigen carriers and/or adjuvants for anti-cancer vaccination.

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.

Biogenetic Vesicle-Based Cancer Vaccines with Tunable Surface Potential and Immune Potency

Cancer vaccines are designed to motivate antigen-specific immune responses and facilitate tumor regression with minimal side effects. To fully exert the potential of vaccines, rationally designed formulations that effectively deliver antigens and trigger potent immune reactions are urgently needed. This study demonstrates a simple and controllable vaccine-developing strategy that assembles tumor antigens into bacterial outer membrane vesicles (OMVs), natural delivery vehicles with intrinsic immune adjuvant properties, via electrostatic interaction. This OMV-delivered vaccine (OMVax) stimulated both innate and adaptive immune responses, leading to enhanced metastasis inhibition and prolonged survival of tumor-bearing mice. Moreover, the influence of different surface charged OMVax on antitumor immunity activation is investigated and declined immune response activation occurred with increased positive surface charge. Together, these findings suggest a simple vaccine formulation that can be enhanced by optimizing the surface charges of vaccine formulations.

Emerging advances in nanomedicine for breast cancer immunotherapy: opportunities and challenges

Breast cancer is one of the most common causes of cancer-related morbidity and mortality in women worldwide. Early diagnosis and an appropriate therapeutic approach for all cancers are climacterics for a favorable prognosis. Targeting the immune system in breast cancer is already a clinical reality with notable successes, specifically with checkpoint blockade antibodies and chimeric antigen receptor T-cell therapy. However, there have been inevitable setbacks in the clinical application of cancer immunotherapy, including inadequate immune responses due to insufficient delivery of immunostimulants to immune cells and uncontrolled immune system modulation. Rapid advancements and new evidence have suggested that nanomedicine-based immunotherapy may be a viable option for treating breast cancer.

Targeting the PD-1/PD-L1 axis for cancer treatment: a review on nanotechnology

Although nanomedicines have been in the oncology field for almost three decades with the introduction of doxil, only a few nanomedicine products have reached approval. Can nanotechnology be a realistic tool to reduce the number of hospital beds? At present, several clinically approved anti-PD-1/PD-L1 antibodies or CAR T cell-based therapies are available; however, the immunotherapy field is far from mature. Will immunotherapy be the fourth pillar of cancer treatment? In this review, we summarized the current status of immunotherapy using PD-1/PD-L1-targeting nanocarriers. The knowledge on material science, therapeutic agents and formulation designs could pave the way for high-efficacy treatment outcomes.

The Landscape of Nanovectors for Modulation in Cancer Immunotherapy

Immunotherapy represents a promising strategy for the treatment of cancer, which functions via the reprogramming and activation of antitumor immunity. However, adverse events resulting from immunotherapy that are related to the low specificity of tumor cell-targeting represent a limitation of immunotherapy's efficacy. The potential of nanotechnologies is represented by the possibilities of immunotherapeutical agents being carried by nanoparticles with various material types, shapes, sizes, coated ligands, associated loading methods, hydrophilicities, elasticities, and biocompatibilities. In this review, the principal types of nanovectors (nanopharmaceutics and bioinspired nanoparticles) are summarized along with the shortcomings in nanoparticle delivery and the main factors that modulate efficacy (the EPR effect, protein coronas, and microbiota). The mechanisms by which nanovectors can target cancer cells, the tumor immune microenvironment (TIME), and the peripheral immune system are also presented. A possible mathematical model for the cellular communication mechanisms related to exosomes as nanocarriers is proposed.

Targeting circulating monocytes with CCL2-loaded liposomes armed with an oncolytic adenovirus

Oncolytic viruses (OVs) selectively replicate in and destroy cancer cells resulting in anti-tumor immunity. However, clinical use remains a challenge because of virus clearance upon intravenous delivery. OV packaging using a nanomedicine approach could overcome this. Here we encapsulate an oncolytic adenovirus (Ad[I/PPT-E1A]) into CCL2-coated liposomes in order to exploit recruitment of CCR2-expressing circulating monocytes into tumors. We demonstrate successful encapsulation of Ad[I/PPT-E1A] into CCL2-coated liposomes that were preferentially taken up by CCR2-expressing monocytes. No complex-related toxicities were observed following incubation with prostate tumor cells and the encapsulation did not affect virus oncolytic activity in vitro. Furthermore, intravenous administration of our nanomedicine resulted in a significant reduction in tumor size and pulmonary metastasis in prostate cancer-bearing mice whereby a 1000-fold less virus was needed compared to Ad[I/PPT-E1A] alone. Taken together our data provide an opportunity to target OVs via circulation to inaccessible tumors using liposome-assisted drug delivery.

Cancer immunotherapy: Challenges and limitations

Although cancer immunotherapy has taken center stage in mainstream oncology inducing complete and long-lasting tumor regression, only a subset of patients receiving treatment respond and others relapse after an initial response. Different tumor types respond differently, and even in cancer types that respond (hot tumors), we still observe tumors that are unresponsive (cold tumors), suggesting the presence of resistance. Hence, the development of intrinsic or acquired resistance is a big challenge for the cancer immunotherapy field. Resistance to immunotherapy, including checkpoint inhibitors, CAR-T cell therapy, oncolytic viruses, and recombinant cytokines arises due to cancer cells employing several mechanisms to evade immunosurveillance.

Core Hydrophobicity of Supramolecular Nanoparticles Induces NLRP3 Inflammasome Activation

Designer nanomaterials capable of delivering immunomodulators to specific immune cells have been extensively studied. However, emerging evidence suggests that several of these nanomaterials can nonspecifically activate NLRP3 inflammasomes, an intracellular multiprotein complex controlling various immune cell functions, leading to undesirable effects. To understand what nanoparticle attributes activate inflammasomes, we designed a multiparametric polymer supramolecular nanoparticle system to modulate various surface and core nanoparticle-associated molecular patterns (NAMPs), one at a time. We also investigated several underlying signaling pathways, including lysosomal rupture-cathepsin B maturation and calcium flux-mitochondrial ROS production, to gain mechanistic insights into NAMPs-mediated inflammasome activation. Here, we report that out of the four NAMPs tested, core hydrophobicity strongly activates and positively correlates with the NLRP3 assembly compared to surface charge, core rigidity, and surface hydrophobicity. Moreover, we demonstrate different signaling inclinations and kinetics followed by differential core hydrophobicity patterns with the most hydrophobic ones exhibiting both lysosomal rupture and calcium influx early on. Altogether, this study will help design the next generation of polymeric nanomaterials for specific regulation of inflammasome activation, aiding efficient immunotherapy and vaccine delivery.

Design and Encapsulation of Immunomodulators onto Gold Nanoparticles in Cancer Immunotherapy

The aim of cancer immunotherapy is to reactivate autoimmune responses to combat cancer cells. To stimulate the immune system, immunomodulators, such as adjuvants, cytokines, vaccines, and checkpoint inhibitors, are extensively designed and studied. Immunomodulators have several drawbacks, such as drug instability, limited half-life, rapid drug clearance, and uncontrolled immune responses when used directly in cancer immunotherapy. Several strategies have been used to overcome these limitations. A simple and effective approach is the loading of immunomodulators onto gold-based nanoparticles (GNPs). As gold is highly biocompatible, GNPs can be administered intravenously, which aids in increasing cancer cell permeability and retention time. Various gold nanoplatforms, including nanospheres, nanoshells, nanorods, nanocages, and nanostars have been effectively used in cancer immunotherapy. Gold nanostars (GNS) are one of the most promising GNP platforms because of their unusual star-shaped geometry, which significantly increases light absorption and provides high photon-to-heat conversion efficiency due to the plasmonic effect. As a result, GNPs are a useful vehicle for delivering antigens and adjuvants that support the immune system in killing tumor cells by facilitating or activating cytotoxic T lymphocytes. This review represents recent progress in encapsulating immunomodulators into GNPs for utility in a cancer immunotherapeutic regimen.

Toxicity of gold nanoparticles (AuNPs): A review

Gold nanoparticles are a kind of nanomaterials that have received great interest in field of biomedicine due to their electrical, mechanical, thermal, chemical and optical properties. With these great potentials came the consequence of their interaction with biological tissues and molecules which presents the possibility of toxicity. This paper aims to consolidate and bring forward the studies performed that evaluate the toxicological aspect of AuNPs which were categorized into in vivo and in vitro studies. Both indicate to some extent oxidative damage to tissues and cell lines used in vivo and in vitro respectively with the liver, spleen and kidney most affected. The outcome of these review showed small controversy but however, the primary toxicity and its extent is collectively determined by the characteristics, preparations and physicochemical properties of the NPs. Some studies have shown that AuNPs are not toxic, though many other studies contradict this statement. In order to have a holistic inference, more studies are required that will focus on characterization of NPs and changes of physical properties before and after treatment with biological media. So also, they should incorporate controlled experiment which includes supernatant control Since most studies dwell on citrate or CTAB-capped AuNPs, there is the need to evaluate the toxicity and pharmacokinetics of functionalized AuNPs with their surface composition which in turn affects their toxicity. Functionalizing the NPs surface with more peculiar ligands would however help regulate and detoxify the uptake of these NPs.

Recent Advances in Immunosafety and Nanoinformatics of Two-Dimensional Materials Applied to Nano-imaging

Two-dimensional (2D) materials have emerged as an important class of nanomaterials for technological innovation due to their remarkable physicochemical properties, including sheet-like morphology and minimal thickness, high surface area, tuneable chemical composition, and surface functionalization. These materials are being proposed for new applications in energy, health, and the environment; these are all strategic society sectors toward sustainable development. Specifically, 2D materials for nano-imaging have shown exciting opportunities in in vitro and in vivo models, providing novel molecular imaging techniques such as computed tomography, magnetic resonance imaging, fluorescence and luminescence optical imaging and others. Therefore, given the growing interest in 2D materials, it is mandatory to evaluate their impact on the immune system in a broader sense, because it is responsible for detecting and eliminating foreign agents in living organisms. This mini-review presents an overview on the frontier of research involving 2D materials applications, nano-imaging and their immunosafety aspects. Finally, we highlight the importance of nanoinformatics approaches and computational modeling for a deeper understanding of the links between nanomaterial physicochemical properties and biological responses (immunotoxicity/biocompatibility) towards enabling immunosafety-by-design 2D materials.

Emerging advances in cationic liposomal cancer nanovaccines: opportunities and challenges

Advancements in the field of cancer therapeutics have witnessed a recent surge in the use of liposomes. The physicochemical characteristics of the liposomes and their components, including the lipid phase transition temperature, vesicular size and size distribution, surface properties, and route of administration, play a significant role in the modulation of the immune response as an adjuvant and for loaded antigen (Ag). Cationic liposomes, concerning their potential ability to amplify the immunogenicity of the loaded Ag/adjuvant, have received enormous interest as a promising vaccine delivery platform for cancer immunotherapy. In the present review, the physicochemical considerations for the development of Ag/adjuvant-loaded liposomes and the cationic liposomes' effectiveness for promoting cancer immunotherapy have been summarized.

Combination Cancer Immunotherapy of Nanoparticle-Based Immunogenic Cell Death Inducers and Immune Checkpoint Inhibitors

Cancer immunotherapy is a promising treatment strategy that aims to strengthen immune responses against cancer. However, the low immunogenicity of tumor cells and inhibition of effector T cells in the tumor immunosuppressive microenvironment remain two major challenges. Immunogenic cell death (ICD) inducers not only directly kill cancer cells but also increase the tumor immunogenicity and induce antitumor immune responses. Immune checkpoint inhibitors can alleviate the inhibition of immune cells. Significantly, the combination of ICD inducers and immune checkpoint inhibitors elicits a remarkable antitumor effect. Nanoparticles confer the ability to modulate systemic biodistribution and achieve targeted accumulation of administered therapeutic agents, thereby facilitating the clinical translation of immunotherapies based on ICD inducers in a safe and effective manner. In this review, we summarize the nanoparticle-based chemical and physical cues that induce effective tumor ICD and elicit an antitumor immune response. In particular, combination of ICD inducers with immune checkpoint inhibitors can further reverse immunosuppression and prevent tumor metastasis and recurrence. An overview of the future challenges and prospects is also provided.

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.

Nanoparticles in cancer immunotherapies: An innovative strategy

Cancer has been one of the most significant causes of mortality, worldwide. Cancer immunotherapy has recently emerged as a competent, cancer-fighting clinical strategy. Nevertheless, due to the difficulty of such treatments, costs, and off-target adverse effects, the implementation of cancer immunotherapy described by the antigen-presenting cell (APC) vaccine and chimeric antigen receptor T cell therapy ex vivo in large clinical trials have been limited. Nowadays, the nanoparticles theranostic system as a promising target-based modality provides new opportunities to improve cancer immunotherapy difficulties and reduce their adverse effects. Meanwhile, the appropriate engineering of nanoparticles taking into consideration nanoparticle characteristics, such as, size, shape, and surface features, as well as the use of these physicochemical properties for suitable biological interactions, provides new possibilities for the application of nanoparticles in cancer immunotherapy. In this review article, we focus on the latest state-of-the-art nanoparticle-based antigen/adjuvant delivery vehicle strategies to professional APCs and engineering specific T lymphocyte required for improving the efficiency of tumor-specific immunotherapy.

Opportunities, Barriers, and a Strategy for Overcoming Translational Challenges to Therapeutic Nucleic Acid Nanotechnology

Recent clinical successes using therapeutic nucleic acids (TNAs) have accelerated the transition of nucleic acid nanotechnology toward therapeutic applications. Significant progress in the development, production, and characterization of nucleic acid nanomaterials and nucleic acid nanoparticles (NANPs), as well as abundant proof-of-concept data, are paving the way toward biomedical applications of these materials. This recent progress has catalyzed the development of new strategies for biosensing, imaging, drug delivery, and immunotherapies with previously unrecognized opportunities and identified some barriers that may impede the broader clinical translation of NANP technologies. A recent workshop sponsored by the Kavli Foundation and the Materials Research Society discussed the future directions and current challenges for the development of therapeutic nucleic acid nanotechnology. Herein, we communicate discussions on the opportunities, barriers, and strategies for realizing the clinical grand challenge of TNA nanotechnology, with a focus on ways to overcome barriers to advance NANPs to the clinic.

Liposome-Based Bioassays

This review highlights the potential of using liposomes in bioassays. Liposomes consist of nano- or micro-sized, synthetically constructed phospholipid vesicles. Liposomes can be loaded with a number of reporting molecules that allow a dramatic amplification of the detection threshold in bioassays. Liposome-based sensors bind or react with the biological components of targets through the introduction of properly tailored vectors anchored on their external surface. The use of liposome-based formulations allows the set-up of bioassays that are rapid, sensitive, and often suitable for in-field applications. Selected applications in the field of immunoassays, as well as recognition/assessment of corona proteins, nucleic acids, exosomes, bacteria, and viruses are surveyed. The role of magnetoliposomes is also highlighted as an additional tool in the armory of liposome-based systems for bioassays.

Vaccination with dendritic cells pulsed ex vivo with gp100 peptide-decorated liposomes enhances the efficacy of anti PD-1 therapy in a mouse model of melanoma

BACKGROUND

Targeting antigens to dendritic cells (DCs) via nanoparticles is a powerful strategy which improves the efficacy of ex vivo antigen-pulsed DC vaccines.

METHODS

In this study, liposomes were first decorated with gp100_25-33 self-antigen and then characterized. Then, DCs were pulsed ex vivo with liposomal gp100 and injected subcutaneously in mice bearing B16F10 established melanoma tumors in combination with anti-PD-1 therapy.

RESULTS

Treatment with liposomal pulsed DC vaccine elicited the strongest anticancer immunity and enhanced intratumoral immune responses based on infiltration of gp100-specific CD4+ and CD8+ T cells to the tumor leading to significant tumor growth regression and prolonged survival rate. Treatment with liposomal pulsed DC vaccine also markedly enhanced specific cytotoxic T lymphocytes (CTL) responses with a significant higher titer of IFN-γ in the spleen. Moreover, a significant increase of PD-1 expressing CD8+ tumor infiltrating lymphocytes (TILs) was detected in tumors.

CONCLUSION

Our results demonstrate an optimum dose of liposomal gp100 significantly increases the efficacy of anti-PD-1 therapy in mice and might be an effective strategy to overcome resistance to anti-PD-1 therapy.

Nanoparticle-based immunotherapy: state of the art and future perspectives

INTRODUCTION

For several years now, medicine has been benefiting from the contribution of nanoparticles (NPs) technology for both diagnosis and therapy. They can be used as adjuvants, being capable per se of immune-modulating activity, or as carriers for molecules to be transported to a specific target, eventually loaded with specific ligands favoring specific uptake.

AREAS COVERED

The review focuses on experimental use of NPs as adjuvants/carriers for allergen immunotherapy (AIT). Human clinical trials conducted so far are discussed.

EXPERT OPINION

Results of experimental studies and recent clinical trials support the use of NPs as carrier/adjuvant in AIT. Comparisons between NP-based and classical AIT are needed, to show the usefulness of the NP-based approach. However, there are still unsolved problems: the persistence of non-degradable NPs with possible toxicological consequences, and the formation of the protein corona around the NPs, which could alter their activity and fate. Virus-like particles seem the most promising NPs for allergy treatment, as for other vaccines. Over the next decade, NP-based AIT will be largely used to treat allergic disorders.

Nucleic Acid Nanoparticles at a Crossroads of Vaccines and Immunotherapies

Vaccines and immunotherapies involve a variety of technologies and act through different mechanisms to achieve a common goal, which is to optimize the immune response against an antigen. The antigen could be a molecule expressed on a pathogen (e.g., a disease-causing bacterium, a virus or another microorganism), abnormal or damaged host cells (e.g., cancer cells), environmental agent (e.g., nicotine from a tobacco smoke), or an allergen (e.g., pollen or food protein). Immunogenic vaccines and therapies optimize the immune response to improve the eradication of the pathogen or damaged cells. In contrast, tolerogenic vaccines and therapies retrain or blunt the immune response to antigens, which are recognized by the immune system as harmful to the host. To optimize the immune response to either improve the immunogenicity or induce tolerance, researchers employ different routes of administration, antigen-delivery systems, and adjuvants. Nanocarriers and adjuvants are of particular interest to the fields of vaccines and immunotherapy as they allow for targeted delivery of the antigens and direct the immune response against these antigens in desirable direction (i.e., to either enhance immunogenicity or induce tolerance). Recently, nanoparticles gained particular attention as antigen carriers and adjuvants. This review focuses on a particular subclass of nanoparticles, which are made of nucleic acids, so-called nucleic acid nanoparticles or NANPs. Immunological properties of these novel materials and considerations for their clinical translation are discussed.

Immunomodulatory Nanosystems

Immunotherapy has emerged as an effective strategy for the prevention and treatment of a variety of diseases, including cancer, infectious diseases, inflammatory diseases, and autoimmune diseases. Immunomodulatory nanosystems can readily improve the therapeutic effects and simultaneously overcome many obstacles facing the treatment method, such as inadequate immune stimulation, off-target side effects, and bioactivity loss of immune agents during circulation. In recent years, researchers have continuously developed nanomaterials with new structures, properties, and functions. This Review provides the most recent advances of nanotechnology for immunostimulation and immunosuppression. In cancer immunotherapy, nanosystems play an essential role in immune cell activation and tumor microenvironment modulation, as well as combination with other antitumor approaches. In infectious diseases, many encouraging outcomes from using nanomaterial vaccines against viral and bacterial infections have been reported. In addition, nanoparticles also potentiate the effects of immunosuppressive immune cells for the treatment of inflammatory and autoimmune diseases. Finally, the challenges and prospects of applying nanotechnology to modulate immunotherapy are discussed.

Influenza mimetic protein-polymer nanoparticles as antigen delivery vehicles to dendritic cells for cancer immunotherapy

Stimulation of dendritic cells (DCs) by antigens (Ags) promotes an Ag-specific immune response that kills Ag-expressing pathogens. These biologically inspired nanocarriers have received much attention as tools to deliver cancer Ags to DCs. A polymer-templated protein nanoball having hemagglutinin (H1-NB) that mimics the influenza virus can be used as a cancer Ag delivery vehicle, as DCs show effective phagocytic activities against H1-NB without any adjuvant. In the present study, H1-NB containing ovalbumin (OVA), a model Ag (H1-OVA-NB), was prepared as an anti-cancer agent and evaluated for its effect on anticancer immunity. H1-OVA-NB treatments in C57BL/6 mice enhanced OVA-specific immune activation and efficiently inhibited B16-OVA tumor growth compared to control groups. Our results indicate that H1-NB is an effective carrier for Ag delivery to DCs and promotes immunotherapy to fight cancer.

Gold nanoparticles in chemo-, immuno-, and combined therapy: review [Invited]

Functionalized gold nanoparticles (GNPs) with controlled geometrical and optical properties have been the subject of intense research and biomedical applications. This review summarizes recent data and topical problems in nanomedicine that are related to the use of variously sized, shaped, and structured GNPs. We focus on three topical fields in current nanomedicine: (1) use of GNP-based nanoplatforms for the targeted delivery of anticancer and antimicrobial drugs and of genes; (2) GNP-based cancer immunotherapy; and (3) combined chemo-, immuno-, and phototherapy. We present a summary of the available literature data and a short discussion of future work.

Releasing the Immune System Brakes Using siRNAs Enhances Cancer Immunotherapy

Therapeutic dendritic cell (DC) cancer vaccines rely on the immune system to eradicate tumour cells. Although tumour antigen-specific T cell responses have been observed in most studies, clinical responses are fairly low, arguing for the need to improve the design of DC-based vaccines. The incorporation of small interfering RNAs (siRNAs) against immunosuppressive factors in the manufacturing process of DCs can turn the vaccine into potent immune stimulators. Additionally, siRNA modification of ex vivo-expanded T cells for adoptive immunotherapy enhanced their killing potency. Most of the siRNA-targeted immune inhibitory factors have been successful in that their blockade produced the strongest cytotoxic T cell responses in preclinical and clinical studies. Cancer patients treated with the siRNA-modified DC vaccines showed promising clinical benefits providing a strong rationale for further development of these immunogenic vaccine formulations. This review covers the progress in combining siRNAs with DC vaccines or T cell therapy to boost anti-tumour immunity.

Nanoparticles: Properties and Applications in Cancer Immunotherapy

BACKGROUND

Tumours are no longer regarded as isolated masses of aberrantly proliferating epithelial cells. Rather, their properties depend on complex interactions between epithelial cancer cells and the surrounding stromal compartment within the tumour microenvironment. In particular, leukocyte infiltration plays a role in controlling tumour development and is now considered one of the hallmarks of cancer. Thus, in the last few years, immunotherapy has become a promising strategy to fight cancer, as its goal is to reprogram or activate antitumour immunity to kill tumour cells, without damaging the normal cells and provide long-lasting results where other therapies fail. However, the immune-related adverse events due to the low specificity in tumour cell targeting, strongly limit immunotherapy efficacy. In this regard, nanomedicine offers a platform for the delivery of different immunotherapeutic agents specifically to the tumour site, thus increasing efficacy and reducing toxicity. Indeed, playing with different material types, several nanoparticles can be formulated with different shape, charge, size and surface chemical modifications making them the most promising platform for biomedical applications.

AIM

In this review, we will summarize the different types of cancer immunotherapy currently in clinical trials or already approved for cancer treatment. Then, we will focus on the most recent promising strategies to deliver immunotherapies directly to the tumour site using nanoparticles.

CONCLUSION

Nanomedicine seems to be a promising approach to improve the efficacy of cancer immunotherapy. However, additional investigations are needed to minimize the variables in the production processes in order to make nanoparticles suitable for clinical use.

Nanodelivery systems and stabilized solid-drug nanoparticles for orally administered medicine: current landscape

The use of nanoparticles as a means of targeted delivery of therapeutics and imaging agents could greatly enhance the transport of biologically active contents to specific target tissues, while avoiding or reducing potentially undesired side effects. Generally speaking, the oral route of administration is associated with good patient compliance, as it is convenient, economical, noninvasive, and does not require special training. Here, we review the progress of the utilization of nanodelivery-system carriers or stabilized solid-drug nanoparticles following oral administration, with particular attention on toxicological data. Mechanisms of cytotoxicity are discussed and the problem of extrapolating knowledge to human scenarios highlighted. Additionally, issues associated with administration of drugs via the oral route are underlined, while strategies utilized to overcome these are highlighted. This review aims to offer a balanced overview of strategies currently being used in the application of nanosize constructs for oral medical applications.

Checkpoint Inhibition: Will Combination with Radiotherapy and Nanoparticle-Mediated Delivery Improve Efficacy?

Checkpoint inhibition (CPI) has been a rare success story in the field of cancer immunotherapy. Knowledge gleaned from preclinical studies and patients that do not respond to these therapies suggest that the presence of tumor-infiltrating lymphocytes and establishment of immunostimulatory conditions, prior to CPI treatment, are required for efficacy of CPI. To this end, radiation therapy (RT) has been shown to promote immunogenic cell-death-mediated tumor-antigen release, increase infiltration and cross-priming of T cells, and decreasing immunosuppressive milieu in the tumor microenvironment, hence allowing CPI to take effect. Preclinical and clinical studies evaluating the combination of RT with CPI have been shown to overcome the resistance to either therapy alone. Additionally, nanoparticle and liposome-mediated delivery of checkpoint inhibitors has been shown to overcome toxicities and improve therapeutic efficacy, providing a rationale for clinical investigations of nanoparticle, microparticle, and liposomal delivery of checkpoint inhibitors. In this review, we summarize the preclinical and clinical studies of combined RT and CPI therapies in various cancers, and review findings from studies that evaluated nanoparticle and liposomal delivery of checkpoint inhibitors for cancer treatments.

Bioinspired Hybrid Protein Oxygen Nanocarrier Amplified Photodynamic Therapy for Eliciting Anti-tumor Immunity and Abscopal Effect

An ideal cancer therapeutic strategy is expected to possess potent ability to not only ablate primary tumors but also prevent distance metastasis and relapse. In this study, human serum albumin was hybridized with hemoglobin by intermolecular disulfide bonds to develop a hybrid protein oxygen nanocarrier with chlorine e6 encapsulated (C@HPOC) for oxygen self-sufficient photodynamic therapy (PDT). C@HPOC realized the tumor-targeted co-delivery of photosensitizer and oxygen, which remarkably relieved tumor hypoxia. C@HPOC was favorable for more efficient PDT and enhanced infiltration of CD8⁺ T cells in tumors. Moreover, oxygen-boosted PDT of C@HPOC induced immunogenic cell death, with the release of danger-associated molecular patterns to activate dendritic cells, T lymphocytes, and natural killer cells in vivo. Notably, C@HPOC-mediated immunogenic PDT could destroy primary tumors and effectively suppress distant tumors and lung metastasis in a metastatic triple-negative breast cancer model by evoking systemic anti-tumor immunity. This study provides a paradigm of oxygen-augmented immunogenic PDT for metastatic cancer treatment.

Iron Oxide Colloidal Nanoclusters as Theranostic Vehicles and Their Interactions at the Cellular Level

Advances in surfactant-assisted chemical approaches have led the way for the exploitation of nanoscale inorganic particles in medical diagnosis and treatment. In this field, magnetically-driven multimodal nanotools that perform both detection and therapy, well-designed in size, shape and composition, are highly advantageous. Such a theranostic material—which entails the controlled assembly of smaller (maghemite) nanocrystals in a secondary motif that is highly dispersible in aqueous media—is discussed here. These surface functionalized, pomegranate-like ferrimagnetic nanoclusters (40⁻85 nm) are made of nanocrystal subunits that show a remarkable magnetic resonance imaging contrast efficiency, which is better than that of the superparamagnetic contrast agent Endorem©. Going beyond this attribute and with their demonstrated low cytotoxicity in hand, we examine the critical interaction of such nanoprobes with cells at different physiological environments. The time-dependent in vivo scintigraphic imaging of mice experimental models, combined with a biodistribution study, revealed the accumulation of nanoclusters in the spleen and liver. Moreover, the in vitro proliferation of spleen cells and cytokine production witnessed a size-selective regulation of immune system cells, inferring that smaller clusters induce mainly inflammatory activities, while larger ones induce anti-inflammatory actions. The preliminary findings corroborate that the modular chemistry of magnetic iron oxide nanoclusters stimulates unexplored pathways that could be driven to alter their function in favor of healthcare.

Nanoparticles for dendritic cell-based immunotherapy

Crosstalk among immune cells has attracted considerable attention with the advent of immunotherapy as a novel therapeutic approach for challenging diseases, especially cancer, which is the leading cause of mortality worldwide. Dendritic cells-the key antigen-presenting cells-play a pivotal role in immunological response by presenting exogenous epitopes to T cells, which induces the self-defense mechanisms of the body. Furthermore, nanotechnology has provided promising ways for diagnosing and treating cancer in the last decade. The progress in nanoparticle drug carrier development, combined with enhanced understanding of the immune system, has enabled harnessing of anti-tumor immunity. This review focuses on the recent advances in nanotechnology that have improved the therapeutic efficacy of immunotherapies, with emphasis on dendritic cell physiology and its role in presenting antigens and eliciting therapeutic T cell response.

Targeted delivery of miRNA-204-5p by PEGylated polymer nanoparticles for colon cancer therapy

AIM

miRNAs have been recognized for their potential in cancer therapeutics, and multiple miRNAs were suggested to affect target genes expression. To overcome limitations of free synthetic miRNAs, such as easily degraded in biofluids and limited in cellular uptake, novel miRNAs delivery systems need to be developed.

MATERIALS & METHODS

Using surface-functionalizing technique, poly(D,L-lactide-co-glycolide)/poly(L-lactide)-block-poly(ethylene glycol)-folate polymer nanoparticle (PLGA/PLA-PEG-FA) loaded with miR-204-5p (FA-NPs-miR-204) was developed. The therapeutic efficacy of FA-NPs-miR-204 was evaluated in the Luc-HT-29 xenograft tumor model in vivo.

RESULTS

FA-NPs-miR-204 could be taken up by HT-29  and HCT-116 cells efficiently, resulting in significant inhibitory effect on cell proliferation and promotive effect on cell apoptosis. In vivo study showed that FA-NPs-miR-204 could exert tumor suppressive function in Luc-HT-29 xenograft model.

CONCLUSION

Our study demonstrates a convenient miRNA delivery system that targets tumor tissue and exerts tumor suppressive function, thus demonstrating a potential new therapeutic option for colon cancer.

Nanotechnology Approaches to Improving Cancer Immunotherapy

Cancer immunotherapy is a powerful, growing treatment approach to cancer that can be combined with chemotherapy, radiotherapy, and oncosurgery. Modulating the immune system to enhance anticancer response by several strategies has yielded improved cancer survival. Despite this progress, the success rate for immunotherapy has been below expectations due to unpredictable efficacy and off-target side effects from systemic dosing. Nanotechnology offers numerous different materials and targeting properties to overcome many of these challenges in immunotherapy. In this chapter, we review current immunotherapy and its challenges as well as the latest nanotechnology applications in cancer immunotherapy.