Acid-Ionizable Iron Nanoadjuvant Augments STING Activation for Personalized Vaccination Immunotherapy of Cancer

Nano-immunomodulator amplifies STING activation in tumor-associated macrophages for cancer immunotherapy

The initiation of tumor-specific T cell responses is critically dependent on antigen-presenting cells (APCs). Nevertheless, as the most dominant APCs in tumors, M2-like macrophages largely restrained T cell activation due to inefficient antigen cross-presentation. Herein, we rationally designed a nano-immunomodulator (FANP) to restore the antigen presentation capability of M2-like macrophages by amplifying stimulator of interferon genes (STING) activation. FANPs were fabricated by self-assembly of Fe3+ and Raddeanin A (RA), which rapidly degraded when reaching tumor microenvironment. The released Fe3+ induced the polarization of M2-like TAMs into M1 phenotype, followed by RA stimulation for amplified STING activation, allowing robust antigen cross-presentation and T cell-driven anti-tumor response, leading to effective tumor regression in both immunogenic and poor-immunogenic tumor models. Notably, FANPs exhibited intensive STING activation in human tumor samples, showing potential for clinical impact. Our work offers a simple and robust strategy to re-educate M2-like macrophages by augmenting STING activation for cancer immunotherapy.

Nanovehicles for delivery of antigens and adjuvants as cancer nanovaccines

Cancer vaccines offer a promising strategy for immunotherapy by stimulating the immune system to target and destroy cancer cells. Antigens and adjuvants have been recognized as important components for the preparation of cancer vaccines, with antigens as the keys for immune cells to recognize cancer cells and adjuvants stimulating potent immune effects. Nanovehicles offer great potential advantages for construction of cancer vaccines, including enhanced antigen loading, co-assembly of antigens and adjuvants, targeted delivery, and antigen and adjuvant effects. By leveraging diverse nanovehicles, along with tumor antigens and/or adjuvants, various cancer nanovaccines have been developed, resulting in enhanced immune responses and facilitating the creation of personalized vaccines. This review presents the progress of cancer nanovaccines in clinical trials, systematically summarizing the physicochemical properties and roles of nanovehicles in the delivery of antigens and adjuvants as cancer nanovaccines, including inorganic nanoparticles, polymeric nanovehicles, nanoengineered coordination polymers, lipid nanovehicles, biomimetic nanovehicles, virus-like particles, and self-assembled peptide vehicles. We further discuss challenges in clinical translation and provide insights into future advancements in cancer nanovaccines.

Direct cGAMP Delivery via Iron Oxide Nanoparticles for Enhanced STING Activation and Durable Antitumor Immunity

Activation of the stimulator of interferon genes (STING) pathway holds immense potential for cancer immunotherapy. However, clinical translation of STING agonists such as cyclic GMP-AMP (cGAMP) is hindered by their inherent instability and poor cellular uptake efficacy. Herein, we report an iron oxide nanoparticle (IONP)-based carrier for delivering cGAMP via coordination chemistry. The ribose, phosphate, and adenine on cGAMP were leveraged to directly bind IONP, resulting in cGAMP-functionalized IONPs (Fe-cGAMP). Such a design greatly improved the cellular uptake and STING activation efficacy of cGAMP. Beyond delivery, IONPs promoted reactive oxygen species (ROS) production and activated Toll-like receptors, leading to synergistic immune activation alongside cGAMP. Fe-cGAMP exhibited robust antitumor effects in multiple mouse tumor models. In combination with immune checkpoint inhibitors, Fe-cGAMP could induce complete tumor remission in over 50% of treated mice, and these mice also remain tumor-free upon a subsequent challenge, demonstrating strong and long-lasting antitumor immune responses.

Lymph node macrophage-targeted interferon alpha boosts anticancer immune responses by regulating CD169-positive phenotype of macrophages

BACKGROUND

CD169+ macrophages in lymph nodes (LNs) activate cytotoxic T lymphocytes (CTLs), which play a crucial role in anticancer immunity, through antigen presentation and co-stimulation by CD169. Interferon alpha (IFNα) is capable of inducing the CD169+ phenotype of macrophages; however, its clinical applications have been hindered by pharmacokinetic limitations-low LN distribution and an inability to target macrophages. To overcome these issues, this study genetically fused mouse IFNα (mIFNα) with mannosylated mouse serum albumin (Man-MSA), and investigated the antitumor effects of the hybrid protein (Man-MSA-mIFNα) or its add-on effects with programmed death-ligand 1 (PD-L1) blockade.

METHODS

To confirm the possibility of CD169+ macrophage-mediated T cell priming, positional information about individual immune cells in LNs of cancer patients was obtained. Traits of Man-MSA-mIFNα, which was prepared using Pichia pastoris to form the high-mannose structure, were characterized by several physicochemical methods. To evaluate the lymphatic drainage of Man-MSA-mIFNα, radioiodine or Cy5-labeled Man-MSA-mIFNα was subcutaneously administered in mice, and then the radioactivity or fluorescence in LNs was analyzed. CD169-diphtheria toxin (DT) receptor (CD169-DTR) mice in which LN CD169+ macrophages can be depleted by DT injection were used to verify whether the antitumor effect of Man-MSA-mIFNα is dependent on LN CD169+ macrophages.

RESULTS

Multiplex tissue imaging predicted close proximity of CD169+ macrophages and T cells and positive correlation between the number of CD169+ macrophages and T cells in neighborhoods in LNs of cancer patients. Physicochemical analyses showed that Man-MSA-mIFNα was formed from the fusion of the intact Man-MSA and mIFNα. Man-MSA-mIFNα efficiently induced the CD169+ phenotype of macrophages by its high LN distribution and macrophage-targeting capability, and significantly exerted antitumor activity through CD8+ T cell activation in the LNs, whereas its antitumor effects were canceled in CD169-DTR mice. Finally, combination therapy with PD-L1 blockade markedly suppressed tumor growth in MB49-bearing mice, which exhibit resistance to PD-L1 blockade monotherapy.

CONCLUSIONS

The present study successfully designed and developed Man-MSA-mIFNα, which efficiently induces the CD169+ phenotype in LN macrophages, contributing to the antitumor immunity. The findings suggest that our novel strategy targeting CD169⁺ macrophages could be a promising immunotherapy for cancer patients who are unresponsive to immune checkpoint inhibitors.

Nano-delivery of STING agonists: Unraveling the potential of immunotherapy

The cyclic GMP-AMP synthetase-interferon gene stimulator (cGAS-STING) pathway possesses tremendous potential in immune responses, viral defense, and anti-tumor treatment. Currently, an increasing number of nanocarriers are being engineered to convey STING agonists, with the goal of booSTING the conveying capacity of cGAS-STING agonists and augment the therapeutic potency of STING agonists. In this review, we explore the mechanisms of cGAS-STING activators, the application of different nanocarriers in the STING pathway, and the application of nanocarriers in anti-tumor therapy, antiviral therapy and autoimmune diseases. Additionally, we also discuss the adverse effects of STING pathway activation and the challenges encountered in nano delivery, we hope that future research will delve into the development of new nanocarriers and the clinical translation of nanocarriers in STING-mediated immunotherapy. STATEMENT OF SIGNIFICANCE: The cyclic GMP-AMP synthetase-interferon gene stimulator (cGAS-STING) pathway possesses tremendous potential in immune responses, viral defense, and anti-tumor treatment. In this review, we first explore the activation mechanism of cGAS-STING signal pathway and the diverse array of nanocarriers that have been employed in the context of the STING pathway, such as natural carrier, lipid nanoparticles, polymeric nanoparticles, and inorganic nanoparticles, highlighting their unique properties and the challenges they present in clinical applications. Furthermore, we discuss the research progress regarding nanocarriers in STING-mediated immunotherapy, such as the application of nanocarriers in anti-tumor therapy, antiviral therapy and autoimmune diseases therapy. Finally, the side effects of STING pathway activation and the issues encountered in nano delivery will be discussed, hoping that future research will delve into the development of new nanocarriers and the clinical translation of nanocarriers in STING-mediated immunotherapy.

Antigen self-presenting dendrosomes swallowing nanovaccines boost antigens and STING agonists codelivery for cancer immunotherapy

Cancer vaccines show promise by eliciting tumor-specific cytotoxic T lymphocytes (CTL) responses. Efficient cytosolic co-delivery of antigens and adjuvants to dendritic cells (DCs) is crucial for vaccines to induce anti-tumor immunity. However, peptide- or nucleic acid-based biomolecules like tumor antigens and STING agonist cyclic-di-GMP (cdGMP) are prone to endosomal degradation, resulting in low cytosolic delivery and CTL response rates. Cationic nanocarriers can improve cytosolic delivery, but their positive charges induce off-target effects. Here, we develop cationic poly(ester amide) based nanoparticles co-loaded with antigens and adjuvant cdGMP (NP(cG, OVA)) for efficient cytosolic delivery and swallow them within antigen self-presenting DCs-derived dendrosomes (ODs) for lymph nodes (LNs) homing. The constructed dendrosomes swallowing nanovaccines ODs/NP(cG, OVA) demonstrated significantly reduced liver accumulation and enhanced LNs and DCs targeting compared to NP(cG, OVA). ODs/NP(cG, OVA) effectively cross-dressed the antigen epitopes on the shell to DCs and facilitated internalization of NP(cG, OVA), realizing DCs cytosolic co-delivery of antigens and adjuvants, thereby promoting antigen presentation, maturation and inflammatory cytokines secretion of DCs. Consequently, DCs stimulated by ODs/NP(cG, OVA) effectively induced activation, proliferation, and differentiation of antigen-specific CTLs that provided robust immune protection against tumor invasion. This work presents a powerful vaccine strategy for cancer immunotherapy.

Advances in cancer nanovaccines: a focus on colorectal cancer

Nanotechnology has revolutionized cancer treatment by providing innovative solutions through nanocancer therapies, nanovaccines, and nanoparticles. This review focuses on the application of these technologies in colorectal cancer (CRC), highlighting their progression from preclinical studies to clinical trials. Nanoparticles, including liposomes, silica, gold, and lipid nanoparticles, possess unique properties that enhance drug delivery, improve therapeutic efficacy, and minimize systemic toxicity. Additionally, nanovaccines are being developed to elicit robust immune responses against CRC cells. This paper offers a comprehensive overview of the current state of nanotechnology-based treatments for CRC, emphasizing key preclinical studies and clinical trials that demonstrate their potential. Furthermore, the review discusses the challenges faced in this field. It outlines future directions for research, underscoring the need for ongoing efforts to translate these promising technologies into practical clinical applications.

Amplifying the Antitumor Effect of STING Agonist MSA-2 by Phospholipid Nanoparticles Delivering STING mRNA and Copper-Modified MSA-2 Combination

STING activation is a promising application therapeutic strategy for cancer immunotherapy. In particular, MSA-2 as an oral STING agonist is discovered to have antitumor activity. However, how to improve the antitumor effect of MSA-2 is a very valuable contribution to cancer immunotherapy. Here, we use two strategies to amplify the antitumor effect of MSA-2 by phospholipid nanoparticles delivering STING mRNA and copper-modified MSA-2. We synthesized a new series of ionizable phospholipid nanoparticles and optimized a phospholipid nanoparticle (1AP24) for delivering STING mRNA, increasing the expression of STING protein to bind more MSA-2. Second, we synthesized copper-modified MSA-2 (MSA-2-Cu), which induced cell death by Cu2+ toxicity. Combining 1AP24@STING mRNA and MSA-2-Cu can crucially decrease tumor growth and increase a mouse's survival. It is a new treatment strategy through amplifying the STING pathway.

Metal-modulated T cell antitumor immunity and emerging metalloimmunotherapy

In recent years, increasing evidence has shown that metals play important roles in both innate and adaptive immunity. An emerging concept of metalloimmunotherapy has been proposed, which may accelerate the development of immunotherapy for cancers. Here, we discuss how metals affect T cell function through different signaling pathways. Metals impact the fate of T cells, including their activation, proliferation, cytotoxicity, and differentiation. Most importantly, metals also participate in mitochondrial operation by regulating energy production and reactive oxygen species homeostasis in T cells. We also identified the metal-based mutual effects between tumor cells and T cells in the tumor microenvironment. Overall, the antitumor effect of T cells can be improved by targeting metal metabolism and metalloimmunotherapy, which will be a step forward in the treatment of cancers.

Glioblastoma Cell Lysate and Adjuvant Nanovaccines via Strategic Vaccination Completely Regress Established Murine Tumors

Tumor vaccines have shown great promise for treating various malignancies; however, glioblastoma (GBM), characterized by its immunosuppressive tumor microenvironment, high heterogeneity, and limited accessibility, has achieved only modest clinical benefits. Here, it is reported that GBM cell lysate nanovaccines boosted with TLR9 agonist CpG ODN (GlioVac) via a strategic vaccination regimen achieve complete regression of malignant murine GBM tumors. Subcutaneous administration of GlioVac promotes uptake by cervical lymph nodes and antigen presentation cells, bolstering antigen cross-presentation and infiltration of GBM-specific CD8+ T cells into the tumor. Notably, a regimen involving two subcutaneous and three intravenous vaccinations not only activates systemic anti-GBM immunity but also further enhances the tumor infiltration of cytotoxic T lymphocytes, effectively reshaping the "cold" GBM tumor into a "hot" tumor. This approach led to a state of tumor-free survival in 5 out of 7 mice bearing the established GL261 GBM model with complete protection from tumor rechallenge. In an orthotopic hRas-GBM model induced by a lentiviral plasmid, GlioVac resulted in ≈100% complete tumor regression. These findings suggest that GlioVac provides a personalized therapeutic vaccine strategy for glioblastoma.

Biologically logic-gated Trojan-horse strategy for personalized triple-negative breast cancer precise therapy by selective ferroptosis and STING pathway provoking

Amidst the therapeutic quandaries associated with triple-negative breast cancer (TNBC), an aggressive malignancy distinguished by its immune resistance and limited treatment avenues, the urgent need for innovative solutions is underscored. To conquer the dilemma, we present a groundbreaking approach that ingeniously employs DNA-fragments-containing exosomes (DNA-Exo) and the concept of "biological logic-gates" to achieve precise homing and controlled selective activation of ferroptosis and stimulator interferon genes (STING) pathways. Leveraging insights from our previous research, a nano-Trojan-horse, Fe0@HMON@DNA-Exo, is engineered via in situ Fe0 synthesis within the glutathione (GSH)-responsiveness degradable hollow mesoporous organosilica nanoparticles (HMON) and subsequently enveloped in DNA-Exo derived from 7-ethyl-10-hydroxycamptothecin (SN38)-treated 4T1 cells. Emphasizing the precision of our approach, the DNA-Exo ensures specific 'homing' to TNBC cells, rendering a targeted delivery mechanism. Concurrently, the concept of "biological logic-gates" is employed to dictate a meticulous and selective activation of STING in antigen-presenting cells (APCs) under OR logic-gating with robust immune response and Fe0-based ferroptosis in TNBC cells under AND logic-gating with reactive oxygen species (ROS) storm generation. In essence, our strategy exhibits great potential in transforming the "immunologically cold" nature of TNBC, enabling precise control over cellular responses, illuminating a promising therapeutic paradigm that is comprehensive and productive in pursuing precision oncology and paving the way for personalized TNBC therapies.

Exploring CD169+ Macrophages as Key Targets for Vaccination and Therapeutic Interventions

CD169 is a sialic acid-binding immunoglobulin-like lectin (Siglec-1, sialoadhesin) that is expressed by subsets of tissue-resident macrophages and circulating monocytes. This receptor interacts with α2,3-linked Neu5Ac on glycoproteins as well as glycolipids present on the surface of immune cells and pathogens. CD169-expressing macrophages exert tissue-specific homeostatic functions, but they also have opposing effects on the immune response. CD169+ macrophages act as a pathogen filter, protect against infectious diseases, and enhance adaptive immunity, but at the same time pathogens also exploit them to enable further dissemination. In cancer, CD169+ macrophages in tumor-draining lymph nodes are correlated with better clinical outcomes. In inflammatory diseases, CD169 expression is upregulated on monocytes and on monocyte-derived macrophages and this correlates with the disease state. Given their role in promoting adaptive immunity, CD169+ macrophages are currently investigated as targets for vaccination strategies against cancer. In this review, we describe the studies investigating the importance of CD169 and CD169+ macrophages in several disease settings and the vaccination strategies currently under investigation.

Augmenting Antitumor Immune Effects through the Coactivation of cGAS-STING and NF-κB Crosstalk in Dendritic Cells and Macrophages by Engineered Manganese Ferrite Nanohybrids

The specific activation of dendritic cells (DCs) and tumor-associated macrophages (TAMs) can activate innate and adaptive immune responses to reverse the tumor immunosuppressive microenvironment. In this study, manganese ferrite nanohybrid MnFe5O8@(M1M-DOX) is synthesized to activate cGAS-STING and NF-κB crosstalk in DCs and TAMs. MnFe5O8, as the source of Fe2+/Fe3+ and Mn2+, is encapsulated with a microdose of doxorubicin (DOX) using an M1 macrophage cytomembrane. Fe2+/Fe3+ and DOX can cooperatively induce tumorous ferroptosis, triggering immunogenic cell death (ICD) that exposes tumor antigens. The release of Fe2+/Fe3+ and Mn2+ has intrinsic dual-immunomodulatory effects on the activation of DCs and the reprogramming of TAMs from the M2 to M1 phenotype. Briefly, Fe2+/Fe3+ activates the NF-κB signaling pathway to trigger the activation of STING signaling. Meanwhile, Mn2+ further enhances the activation of STING and stimulates NF-κB in a cascade-activating manner. Thus, the mutually reinforcing dual activation of cGAS-STING and NF-κB crosstalk prompts the strong maturation of DCs and TAMs, synergistically promoting the infiltration of T cells to inhibit primary tumor growth and localized recurrence. This work proposes a strategy for delivering immunomodulatory metal ions in nanoalloy and harnessing the activation of multisignaling pathways in antigen-presenting cells (APCs) to provide perspectives for tumor immunotherapy.

Nano-Oncologic Vaccine for Boosting Cancer Immunotherapy: The Horizons in Cancer Treatment

Nano-oncologic vaccines represent a groundbreaking approach in the field of cancer immunotherapy, leveraging the unique advantages of nanotechnology to enhance the effectiveness and specificity of cancer treatments. These vaccines utilize nanoscale carriers to deliver tumor-associated antigens and immunostimulatory adjuvants, facilitating targeted immune activation and promoting robust antitumor responses. By improving antigen presentation and localizing immune activation within the tumor microenvironment, nano-oncologic vaccines can significantly increase the efficacy of cancer immunotherapy, particularly when combined with other treatment modalities. This review highlights the mechanisms through which nano-oncologic vaccines operate, their potential to overcome existing limitations in cancer treatment, and ongoing advancements in design. Additionally, it discusses the targeted delivery approach, such as EPR effects, pH response, ultrasonic response, and magnetic response. The combination therapy effects with photothermal therapy, radiotherapy, or immune checkpoint inhibitors are also discussed. Overall, nano-oncologic vaccines hold great promise for changing the landscape of cancer treatment and advancing personalized medicine, paving the way for more effective therapeutic strategies tailored to individual patient needs.

mRNA vaccines in the context of cancer treatment: from concept to application

Immuno-oncology has witnessed remarkable advancements in the past decade, revolutionizing the landscape of cancer therapeutics in an encouraging manner. Among the diverse immunotherapy strategies, mRNA vaccines have ushered in a new era for the therapeutic management of malignant diseases, primarily due to their impressive impact on the COVID-19 pandemic. In this comprehensive review, we offer a systematic overview of mRNA vaccines, focusing on the optimization of structural design, the crucial role of delivery materials, and the administration route. Additionally, we summarize preclinical studies and clinical trials to provide valuable insights into the current status of mRNA vaccines in cancer treatment. Furthermore, we delve into a systematic discussion on the significant challenges facing the current development of mRNA tumor vaccines. These challenges encompass both intrinsic and external factors that are closely intertwined with the successful application of this innovative approach. To pave the way for a more promising future in cancer treatments, a deeper understanding of immunological mechanisms, an increasing number of high-quality clinical trials, and a well-established manufacturing platform are crucial. Collaborative efforts between scientists, clinicians, and industry engineers are essential to achieving these goals.

A polymer nanogel-based therapeutic nanovaccine for prophylaxis and direct treatment of tumors via a full-cycle immunomodulation

Construction of a cancer nanovaccine that can simultaneously activate immune cells and exert efficient tumor treatment still remains a challenge. Herein, we showcase a proof-of-concept demonstration of an advanced therapeutic nanovaccine formulation based on poly(N-vinylcaprolactam) nanogels (NGs) which were loaded with manganese dioxide (MnO2), the sonosensitizer chlorin e6 (Ce6), and the immune adjuvant cyclic GMP-AMP (cGAMP). The gels were furthermore coated with apoptotic cancer cell membranes (AM). On the one hand, the AM promoted the recognition of NGs by antigen presenting cells (APCs) in lymph nodes due to their enhanced immunogenicity, then the loaded Mn and cGAMP could mature APCs via stimulator of interferon genes (STING) activation for triggering immunity to prevent tumor growth. On the other hand, the NGs could selectively release Mn2+ for hydroxyl radical production and Ce6 to generate single oxygen under ultrasound irradiation of tumors, respectively, thereby exerting local chemodynamic/sonodynamic therapy to induce immunogenic cell death (ICD). Moreover, the Mn2+ could also activate STING in tumors to synergize with ICD for potentiated immune responses. Overall, the biomimetic NG-based therapeutic nanovaccine could directly evoke immune system, and also conduct local tumor treatment to further activate ICD, thus realizing a full-cycle immunomodulation (tumor killing for ICD/antigen production, and tumor cells/APCs immune activation) to tackle bilateral tumor growth.

Hydrogel systems for spatiotemporal controlled delivery of immunomodulators: engineering the tumor immune microenvironment for enhanced cancer immunotherapy

Tumor immunotherapy, modulating innate and adaptive immunity, has become an important therapeutic strategy. However, the tumor immune microenvironment's (TIME) complexity and heterogeneity challenge tumor immunotherapy. Hydrogel is a hydrophilic three-dimensional (3D) mesh structure with good biocompatibility and drug release control, which is widely used in drug delivery, agriculture, industry, etc. Hydrogels loaded with immune cells, cytokines, immune checkpoint inhibitors, and anti-tumor drugs can achieve targeted delivery and ultimately activate the immune response in the TIME. In this review, we will summarize the components of the TIME and their immune effects, the emerging immunomodulatory agents, the characteristics and functions of hydrogels, and how hydrogels regulate innate and adaptive immune cells in the TIME.

STING-activating dendritic cell-targeted nanovaccines that evoke potent antigen cross-presentation for cancer immunotherapy

Recently, nanovaccine-based immunotherapy has been robustly investigated due to its potential in governing the immune response and generating long-term protective immunity. However, the presentation of a tumor peptide-major histocompatibility complex to T lymphocytes is still a challenge that needs to be addressed for eliciting potent antitumor immunity. Type 1 conventional dendritic cell (cDC1) subset is of particular interest due to its pivotal contribution in the cross-presentation of exogenous antigens to CD8+ T cells. Here, the DC-derived nanovaccine (denoted as Si9GM) selectively targets cDC1s with marginal loss of premature antigen release for effective stimulator of interferon genes (STING)-mediated antigen cross-presentation. Bone marrow dendritic cell (BMDC)-derived membranes, conjugated to cDC1-specific antibody (αCLEC9A) and binding to tumor peptide (OVA257-264), are coated onto dendrimer-like polyethylenimine (PEI)-grafted silica nanoparticles. Distinct molecular weight-cargos (αCLEC9A-OVA257-264 conjugates and 2'3'-cGAMP STING agonists) are loaded in hierarchical center-radial pores that enables lysosome escape for potent antigen-cross presentation and activates interferon type I, respectively. Impressively, Si9GM vaccination leads to the upregulation of cytotoxic T cells, a reduction in tumor regulatory T cells (Tregs), M1/M2 macrophage polarization, and immune response that synergizes with αPD-1 immune checkpoint blockade. This nanovaccine fulfills a dual role for both direct T cell activation as an artificial antigen-presenting cell and DC subset maturation, indicating its utility in clinical therapy and precision medicine.

Personalized nanovaccines for treating solid cancer metastases

Cancer vaccines have garnered attention as a potential treatment for cancer metastases. Nevertheless, the clinical response rate to vaccines remains < 30%. Nanoparticles stabilize vaccines and improve antigen recognition and presentation, resulting in high tumor penetration or accumulation, effective co-distribution of drugs to the secondary lymphatic system, and adaptable antigen or adjuvant administration. Such vaccine-like nanomedicines have the ability to eradicate the primary tumors as well as to prevent or eliminate metastases. This review examines state-of-the-art nanocarriers developed to deliver tumor vaccines to metastases, including synthetic, semi-biogenic, and biogenic nanosystems. Moreover, it highlights the physical and pharmacological properties that enhance their anti-metastasis efficiency. This review also addresses the combination of nanovaccines with cancer immunotherapy to target various steps in the metastatic cascade, drawing insights from preclinical and clinical studies. The review concludes with a critical analysis of the challenges and frameworks linked to the clinical translation of cancer nanovaccines.

cGAS/STING in skin melanoma: from molecular mechanisms to therapeutics

Melanoma, recognized as the most aggressive type of skin cancer, has experienced a notable increase in cases, especially within populations with fair skin. This highly aggressive cancer is largely driven by UV radiation exposure, resulting in the uncontrolled growth and malignant transformation of melanocytes. The cGAS-STING pathway, an immune signaling mechanism responsible for detecting double-stranded DNA in the cytoplasm, is essential for mediating the immune response against melanoma. This pathway serves a dual purpose: it enhances antitumor immunity by activating immune cells, but it can also promote tumor growth when chronically activated by creating an immunosuppressive environment. This review comprehensively examines the multifaceted implication of the cGAS-STING pathway in melanoma pathogenesis and treatment. We explore its molecular mechanisms, including epigenetic regulation, interaction with signaling pathways such as AR signaling, and modulation by various cellular effectors like TG2 and activin-A. The therapeutic potential of modulating the cGAS-STING pathway is highlighted, with promising results from STING agonists, combination therapies with immune checkpoint inhibitors, and novel drug delivery systems, including nanoparticles and synthetic drugs. Our findings underscore the importance of the cGAS-STING pathway in melanoma, presenting it as a critical target for enhancing anti-tumor immunity. By leveraging this pathway, future therapeutic strategies can potentially convert 'cold' tumors into 'hot' tumors, making them more susceptible to immune responses.

Tumor-specific delivery of clickable inhibitor for PD-L1 degradation and mitigating resistance of radioimmunotherapy

Achieving selective and durable inhibition of programmed death ligand 1 (PD-L1) in tumors for T cell activation remains a major challenge in immune checkpoint blockade therapy. We herein presented a set of clickable inhibitors for spatially confined PD-L1 degradation and radioimmunotherapy of cancer. Using metabolic glycan engineering click bioorthogonal chemistry, PD-L1 expressed on tumor cell membranes was labeled with highly active azide groups. This enables covalently binding of the clickable inhibitor with PD-L1 and subsequent PD-L1 degradation. A pH-activatable nanoparticle responding to extracellular acidic pH of tumor was subsequently used to deliver the clickable PD-L1 inhibitor into extracellular tumor microenvironment for depleting PD-L1 on the surface of tumor cell and macrophage membranes in vivo. We further demonstrated that a combination of the clickable PD-L1 inhibitor with radiotherapy (RT) eradicated the established tumor by inhibiting RT-up-regulated PD-L1 in the tumor tissue. Therefore, selective PD-L1 blockade in tumors via the clickable PD-L1 inhibitor offers a versatile approach to promote cancer immunotherapy.

Roadmap on magnetic nanoparticles in nanomedicine

Magnetic nanoparticles (MNPs) represent a class of small particles typically with diameters ranging from 1 to 100 nanometers. These nanoparticles are composed of magnetic materials such as iron, cobalt, nickel, or their alloys. The nanoscale size of MNPs gives them unique physicochemical (physical and chemical) properties not found in their bulk counterparts. Their versatile nature and unique magnetic behavior make them valuable in a wide range of scientific, medical, and technological fields. Over the past decade, there has been a significant surge in MNP-based applications spanning biomedical uses, environmental remediation, data storage, energy storage, and catalysis. Given their magnetic nature and small size, MNPs can be manipulated and guided using external magnetic fields. This characteristic is harnessed in biomedical applications, where these nanoparticles can be directed to specific targets in the body for imaging, drug delivery, or hyperthermia treatment. Herein, this roadmap offers an overview of the current status, challenges, and advancements in various facets of MNPs. It covers magnetic properties, synthesis, functionalization, characterization, and biomedical applications such as sample enrichment, bioassays, imaging, hyperthermia, neuromodulation, tissue engineering, and drug/gene delivery. However, as MNPs are increasingly explored forin vivoapplications, concerns have emerged regarding their cytotoxicity, cellular uptake, and degradation, prompting attention from both researchers and clinicians. This roadmap aims to provide a comprehensive perspective on the evolving landscape of MNP research.

The advance of ultrasound-enabled diagnostics and therapeutics

Point-of-care ultrasound demonstrates significant potential in biomedical research due to its noninvasive, real-time visualization, cost-effectiveness, and other biological benefits. Ultrasound irradiation can precisely control the mechanical and physicochemical effects on pathogenic lesions, enabling real-time visualization, tunable tissue penetration depth, and therapeutic applications. This review summarizes recent advancements in ultrasound-enabled diagnostics and therapeutics, focusing on mechanochemical effects that can be directly integrated into biomedical applications. Additionally, the structure-functionality relationships of sonotheranostic nanoplatforms are systematically discussed, providing insights into the underlying biological effects. Finally, the limitations of current ultrasonic medicine are discussed, along with potential expansions to facilitate patient-centered translations.

A Multi-Functional Nanoadjuvant Coupling Manganese with Toll-Like 9 Agonist Stimulates Potent Innate and Adaptive Anti-Tumor Immunity

The effectiveness of Toll-like 9 agonists (CpG) as an adjuvant for tumor immunotherapy is restricted due to their insufficient ability to activate anti-tumor immunity. To address that, the common nutrient metal ions are explored (Mn2+, Cu2+, Ca2+, Mg2+, Zn2+, Fe3+, and Al3+), identifying Mn2+ as a key enhancer of CpG to mediate immune activation by augmenting the STING-NF-κB pathway. Mn2+ and CpG are then self-assembled with epigallocatechin gallate (EGCG) into a nanoadjuvant MPN/CpG. Local delivery of MPN/CpG effectively inhibits tumor growth in a B16 melanoma-bearing mouse model, reshaping the tumor microenvironment (TME) by repolarizing M2-type tumor-associated macrophages (TAMs) to an M1-type and boosting intra-tumoral infiltration of CD8+/CD4+ T lymphocytes and DCs. Furthermore, compared to free CpG, MPN/CpG exhibits heightened accumulation in lymph nodes, enhancing CpG uptake and DC activation, consequently inducing significant antigen-specific cytotoxic CD8+ T cell immune response and humoral immunity. In a prophylactic tumor-bearing mouse model, MPN/CpG vaccination with OVA antigen significantly delays B16-OVA melanoma growth and extends mouse survival. These findings underscore the potential of MPN/CpG as a multifunctional adjuvant platform to drive powerful innate and adaptive immunity and regulate TME against tumors.

Robust and Sustained STING Pathway Activation via Hydrogel-Based In Situ Vaccination for Cancer Immunotherapy

The stimulator of interferon genes (STING) pathway is crucial for tumor immunity, leading to the exploration of STING agonists as potential immunotherapy adjuvants. However, their clinical application faces obstacles including poor pharmacokinetics, transient activation, and an immunosuppressive tumor microenvironment (TME). Addressing these limitations, our study aims to develop an injectable silk fibroin hydrogel-based in situ vaccine. It incorporates a nanoscale STING agonist, an immunogenic cell death (ICD) inducer, and an immunomodulator to ensure their controlled and sustained release. cGAMP nanoparticles (cGAMPnps) with a core-shell structure ensure optimal delivery of cGAMP to dendritic cells (DCs), thereby activating the STING pathway and fostering DC maturation. ICD-associated damage-associated molecular patterns amplify and prolong STING activation via enhanced type I IFN and other inflammatory pathways, along with delayed degradation of cGAMP and STING. Furthermore, the STING-driven vascular normalization by cGAMPnps and ICD, in conjunction with immunomodulators like antiprogrammed cell death protein 1 antibody (anti-PD-1 Ab) or OX40 ligand (OX40L), effectively remodels the immunosuppressive TME. This in situ gel vaccine, when used independently or with surgery as neoadjuvant/adjuvant immunotherapy, enhances DC and CD8+ T-cell activation, suppressing tumor progression and recurrence across various immunologically cold tumor models. It revolutionizes the application of STING agonists in cancer immunotherapy, offering substantial promise for improving outcomes across a broad spectrum of malignancies.

A Wurster-Type Covalent Organic Framework with Internal Electron Transfer-Enhanced Catalytic Capacity for Tumor Therapy

The low immunogenicity of tumors, along with the abnormal structural and biochemical barriers of tumor-associated vasculature, impedes the infiltration and function of effector T cells at the tumor site, severely inhibiting the efficacy of antitumor immunotherapy. In this study, a cobaloxime catalyst and STING agonist (MSA-2)-coloaded Wurster-type covalent organic framework (Co-TB COF-M) with internal electron transfer-enhanced catalytic capacity was developed as a COF-based immune activator. The covalently anchored cobaloxime adjusts the energy band structure of TB COF and provides it with good substrate adsorption sites, enabling it to act as an electron transmission bridge between the COF and substrate in proton reduction catalytic reactions. This property significantly enhances the sonodynamic catalytic performance. Under sono-irradiation, Co-TB COF-M can produce a substantial amount of reactive oxygen species (ROS) to induce Gasdermin D-mediated pro-inflammatory pyroptosis, thereby effectively enhancing the immunogenicity of tumors. Furthermore, MSA-2 is specifically released in response to ROS at the tumor site, minimizing the off-target side effects. More importantly, Co-TB COF-induced STING activation normalizes tumor vasculature and increases the expression of endothelial T cell adhesion molecules, which greatly enhance the infiltration and function of effector T cells. Thus, Co-TB COF-M as an immune activator could remold the tumor microenvironment, leading to increased infiltration and an improved function of T cells for immunotherapy.

Mannosylated Fluoropolypeptide Nanovaccines Remodeling Tumor Immunosuppressive Microenvironment to Achieve Highly Potent Cancer Immunotherapy

It is challenging for nanovaccines (NVs) to effectively deliver antigens/neoantigens to prime specifically potent immunities and remodel immunosuppressive tumor microenvironment (TME) for combating immune "cold" cancers. Herein, a novel kind of mannosylated fluoropolypeptide NVs of MFPCOFG (i.e., mannosylated fluoropoly(D,L-cysteine) ovalbumin-loaded Fe2+-gallic acid) is designed that synergistically integrates triple antigen-metal-thermoimmunity to remodel immunosuppressive TME and achieve highly potent immunities. MFPCOFG plus near-infrared irradiation (NIR) effectively facilitated antigen uptake and escape, induced the maturation and antigen cross-presentations of dendritic cells and macrophages, polarized anti-inflammatory macrophage phenotype M2 into tumoricial M1, primed potent CD4+/CD8+T cells responses, proinflammatory cytokines secretion and immune memory effects, showcasing triple antigen-metal-thermoimmunity outperforming combo/mono-immunity. Importantly, both MFPCOFG + NIR and personalized NVs can remarkably enhance the tumor infiltration of CD4+/CD8+T and NK cells to boost potent immunities and long-lasting memory effects, reduce regulatory T (Tregs) and M2 to remodel immunosuppressive TME in B16-OVA and 4T1 models, achieving superior tumor prevention, ablation, and tumor relapse and metastasis inhibition, as further orchestrated with anti-PD-1. Consequently, this work opens up a new avenue to design biocompatible polypeptide nanovaccines with potent immune-priming and TME-remodeling capabilities, holding great potentials to combat immune "cold" cancers with clinic-used anti-PD-1 for cancer immunotherapy and personalized immunotherapy.

Iron Boosts Antitumor Type 1 T-cell Responses and Anti-PD1 Immunotherapy

Cancers only develop if they escape immunosurveillance, and the success of cancer immunotherapies relies in most cases on their ability to restore effector T-cell functions, particularly IFNγ production. Revolutionizing the treatment of many cancers, immunotherapies targeting immune checkpoints such as PD1 can increase survival and cure patients. Unfortunately, although immunotherapy has greatly improved the prognosis of patients, not all respond to anti-PD1 immunotherapy, making it crucial to identify alternative treatments that could be combined with current immunotherapies to improve their effectiveness. Here, we show that iron supplementation significantly boosts T-cell responses in vivo and in vitro. The boost was associated with a metabolic reprogramming of T cells in favor of lipid oxidation. We also found that the "adjuvant" effect of iron led to a marked slowdown of tumor cell growth after tumor cell line transplantation in mice. Specifically, our results suggest that iron supplementation promotes antitumor responses by increasing IFNγ production by T cells. In addition, iron supplementation improved the efficacy of anti-PD1 cancer immunotherapy in mice. Finally, our study suggests that, in patients with cancer, the quality and efficacy of the antitumor response following anti-PD1 immunotherapy may be modulated by plasma ferritin levels. In summary, our results suggest the benefits of iron supplementation on the reactivation of antitumor responses and support the relevance of a fruitful association between immunotherapy and iron supplementation.

Advances in Nanomaterials for Immunotherapeutic Improvement of Cancer Chemotherapy

Immuno-stimulative effect of chemotherapy (ISECT) is recognized as a potential alternative to conventional immunotherapies, however, the clinical application is constrained by its inefficiency. Metronomic chemotherapy, though designed to overcome these limitations, offers inconsistent results, with effectiveness varying based on cancer types, stages, and patient-specific factors. In parallel, a wealth of preclinical nanomaterials holds considerable promise for ISECT improvement by modulating the cancer-immunity cycle. In the area of biomedical nanomaterials, current literature reviews mainly concentrate on a specific category of nanomaterials and nanotechnological perspectives, while two essential issues are still lacking, i.e., a comprehensive analysis addressing the causes for ISECT inefficiency and a thorough summary elaborating the nanomaterials for ISECT improvement. This review thus aims to fill these gaps and catalyze further development in this field. For the first time, this review comprehensively discusses the causes of ISECT inefficiency. It then meticulously categorizes six types of nanomaterials for improving ISECT. Subsequently, practical strategies are further proposed for addressing inefficient ISECT, along with a detailed discussion on exemplary nanomedicines. Finally, this review provides insights into the challenges and perspectives for improving chemo-immunotherapy by innovations in nanomaterials.

A bibliometric insight into nanomaterials in vaccine: trends, collaborations, and future avenues

Background

The emergence of nanotechnology has injected new vigor into vaccine research. Nanovaccine research has witnessed exponential growth in recent years; yet, a comprehensive analysis of related publications has been notably absent.

Objective

This study utilizes bibliometric methodologies to reveal the evolution of themes and the distribution of nanovaccine research.

Methods

Using tools such as VOSviewer, CiteSpace, Scimago Graphica, Pajek, R-bibliometrix, and R packages for the bibliometric analysis and visualization of literature retrieved from the Web of Science database.

Results

Nanovaccine research commenced in 1981. The publication volume exponentially increased, notably in 2021. Leading contributors include the United States, the Chinese Academy of Sciences, the "Vaccine", and researcher Zhao Kai. Other significant contributors comprise China, the University of California, San Diego, Veronique Preat, the Journal of Controlled Release, and the National Natural Science Foundation of China. The USA functions as a central hub for international cooperation. Financial support plays a pivotal role in driving research advancements. Key themes in highly cited articles include vaccine carrier design, cancer vaccines, nanomaterial properties, and COVID-19 vaccines. Among 7402 keywords, the principal nanocarriers include Chitosan, virus-like particles, gold nanoparticles, PLGA, and lipid nanoparticles. Nanovaccine is primarily intended to address diseases including SARS-CoV-2, cancer, influenza, and HIV. Clustering analysis of co-citation networks identifies 9 primary clusters, vividly illustrating the evolution of research themes over different periods. Co-citation bursts indicate that cancer vaccines, COVID-19 vaccines, and mRNA vaccines are pivotal areas of focus for current and future research in nanovaccines. "candidate vaccines," "protein nanoparticle," "cationic lipids," "ionizable lipids," "machine learning," "long-term storage," "personalized cancer vaccines," "neoantigens," "outer membrane vesicles," "in situ nanovaccine," and "biomimetic nanotechnologies" stand out as research interest.

Conclusions

This analysis emphasizes the increasing scholarly interest in nanovaccine research and highlights pivotal recent research themes such as cancer and COVID-19 vaccines, with lipid nanoparticle-mRNA vaccines leading novel research directions.

Current status and future directions of nanovaccine for cancer: a bibliometric analysis during 2004-2023

Background

Nanovaccine treatment is an exciting area of research in immunology and personalized medicine, holding great promise for enhancing immune responses and targeting specific diseases. Their small size allows efficient uptake by immune cells, leading to robust immune activation. They can incorporate immune-stimulating molecules to boost vaccine efficacy. Therefore, nanovaccine can be personalized to target tumor-specific antigens, activating the immune system against cancer cells. Currently, there have been ample evidence showing the effectiveness and potential of nanovaccine as a treatment for cancer. However, there was rare bibliometric analysis of nanovaccine for cancer. Here we performed a bibliometric and visual analysis of published studies related to nanovaccine treatment for cancer, providing the trend of future development of nanovaccine.

Methods

We collected the literatures based on the Web of Science Core Collection SCI-Expanded database. The bibliometric analysis was performed via utilizing visualization analysis tools VOSviewer, Co-Occurrence (COOC), Citespace, Bibliometrix (R-Tool of R-Studio), and HitCite.

Results

A total of 517 literatures were included in this study. China is the country with the most publications and the highest total local citation score (TLCS). The Chinese Academy of Sciences holds the largest research count in this field and the most prolific author is Deling Kong from Nankai University. The most prominent journal for publishing in this area is Biomaterials. The researches mainly focus on the therapeutic process of tumor nanovaccines, the particle composition and the application of nanovaccines, suggesting the potential hotspots and trends of nanovaccine.

Conclusion

In this study, we summarized the characteristics and variation trends of publications involved in nanovaccine, and categorized the most influential countries, institutions, authors, journals, hotspots and trends regarding the nanovaccine for cancer. With the continuous development of nanomaterials and tumor immunotherapy, nanovaccine for cancer provides a research field of significant clinical value and potential application.

Rational design of ROS generation nanosystems to regulate innate immunity of macrophages, dendrtical and natural killing cells for immunotherapy

Innate immunity serves as the first line of host defense in the body against pathogenic infections or malignant diseases. Reactive oxygen species (ROS), as vital signaling mediators, can efficiently elicit innate immune responses to oxidative-related stress or damage. In the era of nanomedicine, various immunostimulatory nanosystems have been extensively designed and synthesized to elicit immune responses for the immunotherapy of cancer or infectious diseases. In this review, we emphasize that ROS derived from nanosystems regulates innate immune cells to potentiate immunotherapeutic efficacy, such as primarily dendritic cells, macrophages, or natural killer cells. Meanwhile, we also summarize the pathway of ROS generation triggered by exogenous nanosystems in innate immune cells of DCs, macrophages, and NK cells.

A next-generation STING agonist MSA-2: From mechanism to application

The stimulator of interferon genes (STING) connects the innate and adaptive immune system and plays a significant role in antitumor immunity. Over the past decades, endogenous and CDN-derived STING agonists have been a hot topic in the research of cancer immunotherapies. However, these STING agonists are either in infancy with limited biological effects or have failed in clinical trials. In 2020, a non-nucleotide STING agonist MSA-2 was identified, which exhibited satisfactory antitumor effects in animal studies and is amenable to oral administration. Due to its distinctive binding mode and enhanced bioavailability, there have been accumulating interests and an array of studies on MSA-2 and its derivatives, spanning its structure-activity relationship, delivery systems, applications in combination therapies, etc. Here, we provide a comprehensive review of MSA-2 and interventional strategies based on this family of STING agonists to help more researchers extend the investigation on MSA-2 in the future.

cGAS-STING pathway agonists are promising vaccine adjuvants

Adjuvants are of critical value in vaccine development as they act on enhancing immunogenicity of antigen and inducing long-lasting immunity. However, there are only a few adjuvants that have been approved for clinical use, which highlights the need for exploring and developing new adjuvants to meet the growing demand for vaccination. Recently, emerging evidence demonstrates that the cGAS-STING pathway orchestrates innate and adaptive immunity by generating type I interferon responses. Many cGAS-STING pathway agonists have been developed and tested in preclinical research for the treatment of cancer or infectious diseases with promising results. As adjuvants, cGAS-STING agonists have demonstrated their potential to activate robust defense immunity in various diseases, including COVID-19 infection. This review summarized the current developments in the field of cGAS-STING agonists with a special focus on the latest applications of cGAS-STING agonists as adjuvants in vaccination. Potential challenges were also discussed in the hope of sparking future research interests to further the development of cGAS-STING as vaccine adjuvants.

An Overview of Nanoparticle-Based Delivery Platforms for mRNA Vaccines for Treating Cancer

With its unique properties and potential applications, nanoparticle-based delivery platforms for messenger RNA (mRNA) vaccines have gained significant attention in recent years. Nanoparticles have the advantages of enhancing immunogenicity, targeting delivery, and improving stability, providing a new solution for drug and vaccine delivery. In some clinical studies, a variety of nanoparticle delivery platforms have been gradually applied to a wide range of vaccine applications. Current research priorities are exploring various types of nanoparticles as vaccine delivery systems to enhance vaccine stability and immunogenicity. Lipid nanoparticles (LNPs) have shown promising potential in preclinical and clinical studies on the efficient delivery of antigens to immune cells. Moreover, lipid nanoparticles and other nanoparticles for nucleic acids, especially for mRNA delivery systems, have shown vast potential for vaccine development. In this review, we present various vaccine platforms with an emphasis on nanoparticles as mRNA vaccine delivery vehicles. We describe several novel nanoparticle delivery platforms for mRNA vaccines, such as lipid-, polymer-, and protein-based nanoparticles. In addition, we provide an overview of the anti-tumor immunity of nanovaccines against different tumors in cancer immunotherapy. Finally, we outline future perspectives and remaining challenges for this promising technology of nanoparticle-based delivery platforms for vaccines.

Development of pharmacological immunoregulatory anti-cancer therapeutics: current mechanistic studies and clinical opportunities

Immunotherapy represented by anti-PD-(L)1 and anti-CTLA-4 inhibitors has revolutionized cancer treatment, but challenges related to resistance and toxicity still remain. Due to the advancement of immuno-oncology, an increasing number of novel immunoregulatory targets and mechanisms are being revealed, with relevant therapies promising to improve clinical immunotherapy in the foreseeable future. Therefore, comprehending the larger picture is important. In this review, we analyze and summarize the current landscape of preclinical and translational mechanistic research, drug development, and clinical trials that brought about next-generation pharmacological immunoregulatory anti-cancer agents and drug candidates beyond classical immune checkpoint inhibitors. Along with further clarification of cancer immunobiology and advances in antibody engineering, agents targeting additional inhibitory immune checkpoints, including LAG-3, TIM-3, TIGIT, CD47, and B7 family members are becoming an important part of cancer immunotherapy research and discovery, as are structurally and functionally optimized novel anti-PD-(L)1 and anti-CTLA-4 agents and agonists of co-stimulatory molecules of T cells. Exemplified by bispecific T cell engagers, newly emerging bi-specific and multi-specific antibodies targeting immunoregulatory molecules can provide considerable clinical benefits. Next-generation agents also include immune epigenetic drugs and cytokine-based therapeutics. Cell therapies, cancer vaccines, and oncolytic viruses are not covered in this review. This comprehensive review might aid in further development and the fastest possible clinical adoption of effective immuno-oncology modalities for the benefit of patients.

Decomposable Nanoagonists Enable NIR-Elicited cGAS-STING Activation for Tandem-Amplified Photodynamic-Metalloimmunotherapy

Activation of the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway has emerged as an efficient strategy to improve the therapeutic outcomes of immunotherapy. However, the "constantly active" mode of current STING agonist delivery strategies typically leads to off-target toxicity and hyperimmunity. To address this critical issue, herein a metal-organic frameworks-based nanoagonist (DZ@A7) featuring tumor-specific and near-infrared (NIR) light-enhanced decomposition is constructed for precisely localized STING activation and photodynamic-metalloimmunotherapy. The engineered nanoagonist enabled the generation of mitochondria-targeted reactive oxygen species under NIR irradiation to specifically release mitochondrial DNA (mtDNA) and inhibit the repair of nuclear DNA via hypoxia-responsive drugs. Oxidized tumor mtDNA serves as an endogenous danger-associated molecular pattern that activates the cGAS-STING pathway. Concurrently, NIR-accelerated zinc ions overloading in cancer cells further enhance the cGAS enzymatic activity through metalloimmune effects. By combining the synergistically enhanced activation of the cGAS-STING pathway triggered by NIR irradiation, the engineered nanoagonist facilitated the maturation of dendritic cells and infiltration of cytotoxic T lymphocytes for primary tumor eradication, which also established a long-term anti-tumor immunity to suppress tumor metastasis. Therefore, the developed nanoagonist enabled NIR-triggered, agonist-free, and tandem-amplified activation of the cGAS-STING pathway, thereby offering a distinct paradigm for photodynamic-metalloimmunotherapy.

The future of cancer vaccines against colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) is the second most lethal malignancy worldwide. Immune checkpoint inhibitors (ICIs) benefit only 15% of patients with mismatch repair-deficient/microsatellite instability (dMMR/MSI) CRC. The majority of patients are not suitable due to insufficient immune infiltration. Cancer vaccines are a potential approach for inducing tumor-specific immunity within the solid tumor microenvironment.

AREA COVERED

In this review, we have provided an overview of the current progress in CRC vaccines over the past three years and briefly depict promising directions for further exploration.

EXPERT OPINION

Cancer vaccines are certainly a promising field for the antitumor treatment against CRC. Compared to monotherapy, cancer vaccines are more appropriate as adjuvants to standard treatment, especially in combination with ICI blockade, for microsatellite stable patients. Improved vaccine construction requires neoantigens with sufficient immunogenicity, satisfactory HLA-binding affinity, and an ideal delivery platform with perfect lymph node retention and minimal off-target effects. Prophylactic vaccines that potentially prevent CRC carcinogenesis are also worth investigating. The exploration of appropriate biomarkers for cancer vaccines may benefit prognostic prediction analysis and therapeutic response prediction in patients with CRC. Although many challenges remain, CRC vaccines represent an exciting area of research that may become an effective addition to current guidelines.

A Hybrid Nanoadjuvant Simultaneously Depresses PD-L1/TGF-β1 and Activates cGAS-STING Pathway to Overcome Radio-Immunotherapy Resistance

Currently, certain cancer patients exhibit resistance to radiotherapy due to reduced DNA damage under hypoxic conditions and acquired immune tolerance triggered by transforming growth factor-β1 (TGF-β1) and membrane-localized programmed death ligand-1 (PD-L1). Meanwhile, cytoplasm-distributed PD-L1 induces radiotherapy resistance through accelerating DNA damage repair (DDR). However, the disability of clinically used PD-L1 antibodies in inhibiting cytoplasm-distributed PD-L1 limits their effectiveness. Therefore, a nanoadjuvant is developed to sensitize cancer to radiotherapy via multi-level immunity activation through depressing PD-L1 and TGF-β1 by triphenylphosphine-derived metformin, and activating the cGAS-STING pathway by generating Mn2+ from MnO2 and producing more dsDNA via reversing tumor hypoxia and impairing DDR. Thus, Tpp-Met@MnO2@Alb effectively enhances the efficiency of radiotherapy to inhibit the progression of irradiated local and abscopal tumors and tumor lung metastases, offering a long-term memory of antitumor immunity without discernible side effects. Overall, Tpp-Met@MnO2@Alb has the potential to be clinically applied for overcoming radio-immunotherapy resistance.

Nanocatalytic Anti-Tumor Immune Regulation

Immunotherapy has brought a new dawn for human being to defeat cancer. Although existing immunotherapy regimens (CAR-T, etc.) have made breakthroughs in the treatments of hematological cancer and few solid tumors such as melanoma, the therapeutic efficacy on most solid tumors is still far from being satisfactory. In recent years, the researches on tumor immunotherapy based on nanocatalytic materials are under rapid development, and significant progresses have been made. Nanocatalytic medicine has been demonstrated to be capable of overcoming the limitations of current clinicnal treatments by using toxic chemodrugs, and exhibits highly attractive advantages over traditional therapies, such as the enhanced and sustained therapeutic efficacy based on the durable catalytic activity, remarkably reduced harmful side-effects without using traditional toxic chemodrugs, and so on. Most recently, nanocatalytic medicine has been introduced in the immune-regulation for disease treatments, especially, in the immunoactivation for tumor therapies. This article presents the most recent progresses in immune-response activations by nanocatalytic medicine-initiated chemical reactions for tumor immunotherapy, and elucidates the mechanism of nanocatalytic medicines in regulating anti-tumor immunity. By reviewing the current research progress in the emerging field, this review will further highlight the great potential and broad prospects of nanocatalysis-based anti-tumor immune-therapeutics.

Hypoxia Reversion by Low-Immunogenic Ultra-Acid-Sensitive Comicelles of Protein-Polymer Conjugates Sensitizes Tumors to Photodynamic Therapy

Hypoxia is characteristic of the tumor microenvironment, which is correlated with resistance to photodynamic therapy (PDT), radiotherapy, chemotherapy, and immunotherapy. Catalase is potentially useful to catalyze the conversion of endogenous H2O2 to O2 for hypoxia reversion. However, the efficient delivery of catalase into the hypoxia regions of tumors is a huge challenge. Here, we report the self-assembly of ultra-acid-sensitive polymer conjugates of catalase and albumin into nanomicelles that are responsive to the acidic tumor microenvironment. The immunogenicity of catalase is mitigated by the presence of albumin, which reduces the cross-linking of catalase with B cell receptors, resulting in improved pharmacokinetics. The ultra acid sensitivity of the nanomicelles makes it possible to efficiently escape the lysosomal degradation after endocytosis and permeate into the interior of tumors to reverse hypoxia in vitro and in vivo. In mice bearing triple-negative breast cancer, the nanomicelles loaded with a photosensitizer effectively accumulate and penetrate into the whole tumors to generate a sufficient amount of O2 to reverse hypoxia, leading to enhanced efficacy of PDT without detectable side effects. These findings provide a general strategy of self-assembly to design low-immunogenic ultra-acid-sensitive comicelles of protein-polymer conjugates to reverse tumor hypoxia, which sensitizes tumors to PDT.

Metal-Phenolic Nanocloaks on Cancer Cells Potentiate STING Pathway Activation for Synergistic Cancer Immunotherapy

Due to the presence of natural neoantigens, autologous tumor cells hold great promise as personalized therapeutic vaccines. Yet autologous tumor cell vaccines require multi-step production that frequently leads to the loss of immunoreactive antigens, causing insufficient immune activation and significantly hampering their clinical applications. Herein, we introduce a novel whole-cell cancer vaccine by cloaking cancer cells with lipopolysaccharide-decorated manganese(II)-phenolic networks (MnTA nanocloaks) to evoke tumor-specific immune response for highly efficacious synergistic cancer immunotherapy. The natural polyphenols coordinate with Mn2+ and immediately adhere to the surface of individual cancer cells, thereby forming a nanocloak and encapsulating tumor neoantigens. Subsequent decoration with lipopolysaccharide induces internalization by dendritic cells, where Mn2+ ions are released in the cytosol, further facilitating the activation of the stimulator of the interferon genes (STING) pathway. Highly effective tumor suppression was observed by combining the nanocloaked cancer cell treatment with anti-programmed cell death ligand 1 (anti-PD-L1) antibodies-mediated immune checkpoint blockade therapy. Our work demonstrates a universal yet simple strategy to engineer a cell-based nanobiohybrid system for enhanced cancer immunotherapy.

Antigen Self-Presented Personalized Nanovaccines Boost the Immunotherapy of Highly Invasive and Metastatic Tumors

Dendritic cell (DC)-based vaccines have shown promise in adoptive cell therapy for enhancing the antigen-specific response of antitumor immunity. However, their clinical efficacy is limited by the less-presented tumor-associated antigens (TAAs) through MHC I and low lymph node homing efficiency. Herein, to address these issues, we rationally design and fabricate DC-based nanovaccines by coating Cu2-xSe nanoparticles (CS NPs) with the membrane of matured DCs (named as DCNV(CSD) nanovaccines). We reveal the important roles of CS NPs in the DCNV(CSD) nanovaccines from three aspects: (1) inducing the immunogenic cell death of tumor cells to expose abundant TAAs; (2) promoting the escape of TAAs from the lysosomes of DCs during the antigen presenting process through MHC I; (3) sustainably releasing traces of copper ions to promote the proliferation of T cells. Our DCNV(CSD) nanovaccines are characterized with high expressions of MHC I, CD80, CD86, CCR7, and ICAM-1 proteins, which not only endow them with abundantly processed specific TAAs, but also a strong capability of homing to the lymph nodes. The homing capability of our small DCNV(CSD) nanovaccines is better than that of matured DCs. More importantly, they can elicit the strong response of potent antispecific CD8+ T cells for antitumor immunotherapy, as tested in the treatment of highly invasive glioblastoma and highly metastatic melanoma. Additionally, DCNV(CSD) nanovaccines can generate memory T cells (TEM) in the spleen of mice to effectively prevent the recurrence of treated tumors. This work demonstrates a universal approach to fabricate high-performance DC-based nanovaccines for tumor immunotherapy by using versatile CS NPs.

Chemoimmunotherapeutic Nanogel for Pre- and Postsurgical Treatment of Malignant Melanoma by Reprogramming Tumor-Associated Macrophages

Surgery is the primary method to treat malignant melanoma; however, the residual microtumors that cannot be resected completely often trigger tumor recurrence, causing tumor-related mortality following melanoma resection. Herein, we developed a feasible strategy based on the combinational chemoimmunotherapy by cross-linking carboxymethyl chitosan (CMCS)-originated polymetformin (PolyMetCMCS) with cystamine to prepare stimuli-responsive nanogel (PMNG) owing to the disulfide bond in cystamine that can be cleaved by the massive glutathione (GSH) in tumor sites. Then, chemotherapeutic agent doxorubicin (DOX) was loaded in PMNG, which was followed by a hyaluronic acid coating to improve the overall biocompatibility and targeting ability of the prepared nanogel (D@HPMNG). Notably, PMNG effectively reshaped the tumor immune microenvironment by reprogramming tumor-associated macrophage phenotypes and recruiting intratumoral CD8+ T cells owing to the inherited immunomodulatory capability of metformin. Consequently, D@HPMNG treatment remarkably suppressed melanoma growth and inhibited its recurrence after surgical resection, proposing a promising solution for overcoming lethal melanoma recurrence.

Tumor Microenvironment-Responsive Nanoparticles Amplifying STING Signaling Pathway for Cancer Immunotherapy

Insufficient activation of the stimulator of interferon genes (STING) signaling pathway and profoundly immunosuppressive microenvironment largely limits the effect of cancer immunotherapy. Herein, tumor microenvironment (TME)-responsive nanoparticles (PMM NPs) are exploited that simultaneously harness STING and Toll-like receptor 4 (TLR4) to augment STING activation via TLR4-mediated nuclear factor-kappa B signaling pathway stimulation, leading to the increased secretion of type I interferons (i.e., 4.0-fold enhancement of IFN-β) and pro-inflammatory cytokines to promote a specific T cell immune response. Moreover, PMM NPs relieve the immunosuppression of the TME by decreasing the percentage of regulatory T cells, and polarizing M2 macrophages to the M1 type, thus creating an immune-supportive TME to unleash a cascade adaptive immune response. Combined with an anti-PD-1 antibody, synergistic efficacy is achieved in both inflamed colorectal cancer and noninflamed metastatic breast tumor models. Moreover, rechallenging tumor-free animals with homotypic cells induced complete tumor rejection, indicating the generation of systemic antitumor memory. These TME-responsive nanoparticles may open a new avenue to achieve the spatiotemporal orchestration of STING activation, providing a promising clinical candidate for next-generation cancer immunotherapy.

Nanomaterial-encapsulated STING agonists for immune modulation in cancer therapy

The cGAS-STING signaling pathway has emerged as a critical mediator of innate immune responses, playing a crucial role in improving antitumor immunity through immune effector responses. Targeting the cGAS-STING pathway holds promise for overcoming immunosuppressive tumor microenvironments (TME) and promoting effective tumor elimination. However, systemic administration of current STING agonists faces challenges related to low bioavailability and potential adverse effects, thus limiting their clinical applicability. Recently, nanotechnology-based strategies have been developed to modulate TMEs for robust immunotherapeutic responses. The encapsulation and delivery of STING agonists within nanoparticles (STING-NPs) present an attractive avenue for antitumor immunotherapy. This review explores a range of nanoparticles designed to encapsulate STING agonists, highlighting their benefits, including favorable biocompatibility, improved tumor penetration, and efficient intracellular delivery of STING agonists. The review also summarizes the immunomodulatory impacts of STING-NPs on the TME, including enhanced secretion of pro-inflammatory cytokines and chemokines, dendritic cell activation, cytotoxic T cell priming, macrophage re-education, and vasculature normalization. Furthermore, the review offers insights into co-delivered nanoplatforms involving STING agonists alongside antitumor agents such as chemotherapeutic compounds, immune checkpoint inhibitors, antigen peptides, and other immune adjuvants. These platforms demonstrate remarkable versatility in inducing immunogenic responses within the TME, ultimately amplifying the potential for antitumor immunotherapy.

Nanodelivery Systems as a Novel Strategy to Overcome Treatment Failure of Cancer

Despite the tremendous progress in cancer treatment in recent decades, cancers often become resistant due to multiple mechanisms, such as intrinsic or acquired multidrug resistance, which leads to unsatisfactory treatment effects or accompanying metastasis and recurrence, ultimately to treatment failure. With a deeper understanding of the molecular mechanisms of tumors, researchers have realized that treatment designs targeting tumor resistance mechanisms would be a promising strategy to break the therapeutic deadlock. Nanodelivery systems have excellent physicochemical properties, including highly efficient tissue-specific delivery, substantial specific surface area, and controllable surface chemistry, which endow nanodelivery systems with capabilities such as precise targeting, deep penetration, responsive drug release, multidrug codelivery, and multimodal synergy, which are currently widely used in biomedical researches and bring a new dawn for overcoming cancer resistance. Based on the mechanisms of tumor therapeutic resistance, this review summarizes the research progress of nanodelivery systems for overcoming tumor resistance to improve therapeutic efficacy in recent years and offers prospects and challenges of the application of nanodelivery systems for overcoming cancer resistance.

Dendritic Cell-Based In Situ Nanovaccine for Reprogramming Lipid Metabolism to Boost Tumor Immunotherapy

Cancer vaccines have been considered to be an alternative therapeutic strategy for tumor therapy in the past decade. However, the popularity and efficacy of cancer vaccines were hampered by tumor antigen heterogeneity and the impaired function of cross-presentation in the tumor-infiltrating dendritic cells (TIDCs). To overcome these challenges, we engineered an in situ nanovaccine (named as TPOP) based on lipid metabolism-regulating and innate immune-stimulated nanoparticles. TPOP could capture tumor antigens and induce specific recognition by TIDCs to be taken up. Meanwhile, TPOP could manipulate TIDC lipid metabolism and inhibit de novo synthesis of fatty acids, thus improving the ability of TIDCs to cross-present by reducing their lipid accumulation. Significantly, intratumoral injection of TPOP combined with pretreatment with doxorubicin showed a considerable therapeutic effect in the subcutaneous mouse colorectal cancer model and melanoma model. Moreover, in combination with immune checkpoint inhibitors, such TPOP could markedly inhibit the growth of distant tumors by systemic antitumor immune responses. This work provides a safe and promising strategy for improving the function of immune cells by manipulating their metabolism and activating the immune system effectively for in situ cancer vaccines.

Laser-Activatable In Situ Vaccine Enhances Cancer-Immunity Cycle

The immune response in cancer reflects a series of carefully regulated events; however, current tumor immunotherapies typically address a single key aspect to enhance anti-tumor immunity. In the present study, a nanoplatform (Fe3 O4 @IR820@CpG)-based immunotherapy strategy that targets the multiple key steps in cancer-immunity cycle is developed: 1) promotes the release of tumor-derived proteins (TDPs), including tumor-associated antigens and pro-immunostimulatory factors), in addition to the direct killing effect, by photothermal (PTT) and photodynamic therapy (PDT); 2) captures the released TDPs and delivers them, together with CpG (a Toll-like receptor 9 agonist) to antigen-presenting cells (APCs) to promote antigen presentation and T cell activation; 3) enhances the tumor-killing ability of T cells by combining with anti-programmed death ligand 1 antibody (α-PD-L1), which collectively advances the outstanding of the anti-tumor effects on colorectal, liver and breast cancers. The broad-spectrum anti-tumor activity of Fe3 O4 @IR820@CpG with α-PD-L1 demonstrates that optimally manipulating anti-cancer immunity not singly but as a group provides promising clinical strategies.

Bioactivable STING Nanoagonists to Synergize NIR-II Mild Photothermal Therapy Primed Robust and Long-Term Anticancer Immunity

Pharmacological activation of the stimulator of interferon genes (STING) pathway has become a promising strategy for cancer immunotherapy. However, the insufficient tumorous accumulation, rapid clearance, and short duration of drug efficacy in the tumor microenvironment of small structural STING agonists greatly compromise the therapeutic efficacy. Herein, a tumorous extracellular matrix (ECM) is presented anchoring STING agonist-based photoimmunothernostic nanomedicine (SAPTN) that can be activated by mild-temperature photothermal therapy (mild PTT) induced neutrophilic inflammation. The SAPTN owns second window near-infrared (NIR-II) photonics properties fitting for NIR-II fluorescence and photoacoustic imaging-guided cancer therapy. The aggregates SAPTN targeting to the ECM provide slow and continuous release of potent STING agonists diABZIs. The mild PTT and long-lasting STING agonists released in the ECM synergistically prime systematic, robust, and long-term anticancer immunity. In a tumor model, this approach leads to complete tumor eradication in about 100% of mice with orthotopic breast tumors, and the mice regained tumor-free survival of at least 2 months. In addition, the immune-mediated abscopal effect shows inhibition of the distant solid tumor growth by intratumoral administration of SAPTN with laser irradiation. Overall, this approach represents a generalized photoactivable nanomedicine to prime anticancer immunity for improved cancer theranostics.