STING pathway agonism as a cancer therapeutic

Discovery of 3-(Fluoro-imidazolyl)pyridazine Derivatives as Potent STING Agonists with Antitumor Activity

Stimulator of interferon genes (STING) represents a promising therapeutic target for cancer and infectious diseases due to its ability to activate innate immune responses. Herein, we describe the discovery of 3-(fluoro-imidazolyl) pyridazine derivatives as potent STING agonists. Our comprehensive investigation, including structural and functional analysis as well as molecular dynamics simulation, suggests that appropriate spatial dimensions may play a crucial role in determining agonist efficacy. Notably, our representative STING agonist A4 demonstrates remarkable binding affinities to various hSTING variants and mSTING, effectively activating STING in both human THP1 and mouse RAW 264.7 cells with EC50 values of 0.06 and 14.15 μM, respectively. Furthermore, Compound A4 exhibits an excellent pharmacokinetic profile in C57BL/6 mice, and its systemic administration led to significant tumor regression in the B16.F10 tumor-bearing mice, surpassing the efficacy of SR-717. These findings position A4 as a highly promising STING agonist warranting further advanced preclinical development for tumor immunotherapy.

Advances in polymer nanomaterials targeting cGAS-STING pathway for enhanced cancer immunotherapy

Cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway has been recognized as a promising target for cancer immunotherapy. Although various STING agonists have been developed, their clinical applications are still severely impeded by various issues, such as non-specific accumulation, adverse effects, rapid clearance, etc. In recent years, the emergence of nanomaterials has profoundly revolutionized STING agonists delivery, which promote tumor-targeted delivery, boost the immunotherapeutic effects and reduce systemic toxicity of STING agonists. In particular, polymer nanomaterials possess inherent advantages including controllable structure, tunable function and degradability. These properties afford them the capacity to serve as delivery vehicles for small-molecule STING agonists. Furthermore, the superior characteristics of polymer nanomaterials can enable their utilization as a novel STING agonist to stimulate anti-tumor immunity. In this review, the molecular mechanisms of cGAS-STING pathway activation are discussed. The recent development of small-molecules STING agonists is described. Then polymer nanomaterials are discussed as carriers for STING agonists in cancer immunotherapy, including polymersomes, polymer micelles, polymer capsules, and polymer nanogels. Additionally, polymer nanomaterials are identified as a novel class of STING agonists for efficient cancer immunotherapy, encompassing both polymer materials and polymer-STING agonists conjugates. The review also presents the combination of polymer-based cGAS-STING immunotherapy with chemotherapy, radiotherapy, phototherapy (both photodynamic and photothermal), chemodynamic therapy, and other therapeutic strategies. Furthermore, the discussion highlights recent advancements targeting the cGAS-STING pathway in clinically approved polymer nanomaterials and corresponding potent innovations. Finally, the potential challenges and perspectives of polymer nanomaterials for activating cGAS-STING pathway are outlined, emphasizing the critical scientific issue and hoping to offer guidance for their clinical translation.

Design, Synthesis, and Biological Evaluation of Selective STING Synergists That Enhance cGAMP-STING Pathway Activation without Inherent Agonist Activity

The cGAS-STING pathway is pivotal for innate immunity and antitumor responses. However, the challenge of selectively targeting the diseased tissue without harming the healthy tissue has impeded the development of STING agonists. In this article, we tackle this issue by developing novel STING synergists that target the STING C-terminal domain pocket. Our findings indicate that agonist 12B can boost the cGAMP-STING pathway synergistically. Through reverse optimization of 12B, we synthesized three series of compounds, with compounds 55, 66, and 67 emerging as selective STING synergists that amplify cGAMP-induced pathway activation without inherent agonist properties. Compound 67 emerged as the most potent (EC50 = 20.53 μM), displaying a broad binding affinity across STING-CTD alleles and potent antitumor efficacy in vivo. Notably, it exhibited excellent safety profiles in both in vitro and in vivo models, along with favorable pharmacokinetics. These findings highlight the therapeutic potential of novel STING synergists for cancer immunotherapy.

Gut microbiota in cancer initiation, development and therapy

Cancer has long been associated with genetic and environmental factors, but recent studies reveal the important role of gut microbiota in its initiation and progression. Around 13% of cancers are linked to infectious agents, highlighting the need to identify the specific microorganisms involved. Gut microbiota can either promote or inhibit cancer growth by influencing oncogenic signaling pathways and altering immune responses. Dysbiosis can lead to cancer, while certain probiotics and their metabolites may help reestablish micro-ecological balance and improve anti-tumor immune responses. Research into targeted approaches that enhance therapy with probiotics is promising. However, the effects of probiotics in humans are complex and not yet fully understood. Additionally, methods to counteract harmful bacteria are still in development. Early clinical trials also indicate that modifying gut microbiota may help manage side effects of cancer treatments. Ongoing research is crucial to understand better how gut microbiota can be used to improve cancer prevention and treatment outcomes.

XMT-2056, a HER2-Directed STING Agonist Antibody-Drug Conjugate, Induces Innate Antitumor Immune Responses by Acting on Cancer Cells and Tumor-Resident Immune Cells

PURPOSE

Targeted tumor delivery may be required to potentiate the clinical benefit of innate immune modulators. The objective of the study was to apply an antibody-drug conjugate (ADC) approach to STING agonism and develop a clinical candidate.

EXPERIMENTAL DESIGN

XMT-2056, a HER2-directed STING agonist ADC, was designed, synthesized, and tested in pharmacology and toxicology studies. The ADC was compared with a clinical benchmark intravenously administered a STING agonist.

RESULTS

XMT-2056 achieved tumor-targeted delivery of the STING agonist upon systemic administration in mice and induced innate antitumor immune responses; single dose administration of XMT-2056 induced tumor regression in a variety of tumor models with high and low HER2 expressions. Notably, XMT-2056 demonstrated superior efficacy and reduced systemic inflammation compared with a free STING agonist. XMT-2056 exhibited concomitant immune-mediated killing of HER2-negative cells specifically in the presence of HER2-positive cancer cells, supporting the potential for activity against tumors with heterogeneous HER2 expression. The antibody does not compete for binding with trastuzumab or pertuzumab, and a benefit was observed when combining XMT-2056 with each of these therapies as well as with trastuzumab deruxtecan ADC. The combination of XMT-2056 with anti-PD-1 conferred benefit on antitumor activity and induced immunologic memory. XMT-2056 was well tolerated in nonclinical toxicology studies.

CONCLUSIONS

These data provide a robust preclinical characterization of XMT-2056 and provide rationale and strategy for its clinical evaluation.

Carvedilol sensitizes chemotherapy by targeting STING to boost anti-tumor immunity

The stimulator of interferon genes (STING)-mediated type I interferon (IFN) response is critical for mounting anti-tumor immunity and sensitizing chemotherapy by remodeling the tumor immune microenvironment. However, no clinically available drugs have been applied for STING activation. Based on high-throughput screening of small-molecule microarrays, we found that carvedilol, an adrenergic receptor blocker used to treat essential hypertension and symptomatic heart failure, is a STING activator. Mechanistically, carvedilol interacts with STING at threonine 263 and enhances its dimerization. Importantly, carvedilol enhances the therapeutic effect of etoposide in both the allografted tumor model and patient-derived tumor-like cell clusters (PTCs) by promoting etoposide-induced STING activation. Our findings identify carvedilol as a STING activator and provide a theoretical basis for combining carvedilol and etoposide in cancer therapy.

Inhibiting B-cell-mediated Immunosuppression to Enhance the Immunotherapy Efficacy in Hepatocellular Carcinoma

Background

Immunotherapy is efficacious in hepatocellular carcinoma (HCC), but the benefits are limited to a minority of patients. Most HCC patients show resistance to immune checkpoint blockade (ICB). Agonists of the stimulator of interferon genes (STING), potent immune stimulators, showed limited effectiveness. Using preclinical models, we studied the mechanisms of resistance to ICB and STING agonism.

Methods

Murine HCA-1 and RIL-175 HCCs were orthotopically grown in mice with underlying liver fibrosis, to mimic the presentation of human HCC. Established tumors were treated with a STING agonist (BMS-986301) or anti-PD1 ICB, and mice were followed to evaluate safety and efficacy, as well as the mechanisms of treatment resistance by RNA sequencing, flow cytometry, and immunofluorescence, B-cell depletion and T-cell immunoglobulin and mucin domain 1 (TIM-1) ICB.

Results

Unbiased analyses of transcriptomic data from murine HCC tissues from ICB-treated mice showed an increased abundance of intratumoral CD8+ T cells and B cells. STING agonism alone showed efficacy in the ICB-responsive RIL-175 HCC model but more limited efficacy in the ICB-resistant HCA-1 model. STING agonism increased circulating IL-10 and intratumoral infiltration by B-cells, including TIM-1+ B cells, and promoted the formation of tertiary lymphoid structure (TLS)-like structures, especially in the peritumoral areas. Strikingly, adding B cell depletion to ICB or STING agonism treatment significantly increased survival. Interestingly, unlike ICB, STING agonism also had a pronounced anti-metastatic activity. In addition, the combination of STING agonism and TIM-1 blockade augmented B cell differentiation and antigen presentation in vitro and improved the anti-tumor effects in murine HCC in vivo. This approach decreased the number of TIM-1+ B cells in the tumor and shifted B cells to higher expression of CD86 and MHC class II, enhancing the antigen presentation capability and further boosting the antitumor efficacy of CD8+ cytotoxic T cells.

Conclusion

Our findings demonstrate that B cells are associated with ICB- and STING-mediated therapy resistance, and that depleting B-cells or targeting TIM-1 enhances both innate and acquired therapeutic efficacy in HCC.

Synergistic chemo-immunotherapy for osteosarcoma via a pH-responsive multi-component nanoparticle system

Introduction

Osteosarcoma (OS) is the most common primary malignant bone tumor in pediatric populations. Its treatment is complicated by chemotherapy-induced toxicity and limited induction of immunogenic cell death (ICD).

Methods

To address these challenges, we developed a pH-responsive, multi-component nanoparticle system designed to co-deliver doxorubicin (DOX), monophosphoryl lipid A (MPLA), and a PD-1/PD-L1-targeting peptide, integrated with the immune-modulating polymer PEG-PC7A. The system was optimized using both one-factor-at-a-time (OFAT) and Box-Behnken design (BBD).

Results

The optimized nanoparticles had a hydrodynamic size of 110 nm, high encapsulation efficiency (97.15%), and pH-sensitive drug release (91% at pH 6.5). In vitro studies showed enhanced ICD markers, including calreticulin exposure and ATP/HMGB1 release, aswell as synergistic dendritic cell maturation via dual STING/TLR4 pathway activation. In an orthotopic LM8 osteosarcoma model, the nanoparticles significantly suppressed tumor growth, promoted cytotoxic T lymphocyte infiltration, reduced regulatory T cells, and established long-term immune memory.

Discussion

The combination of ICD induction, innate immune activation, and checkpoint blockade reprogrammed the tumor microenvironment, amplifying anti-tumor immune responses. These results demonstrate the potential of this multifunctional nanoparticle platform as an effective immunochemotherapeutic strategy for osteosarcoma, offering enhanced therapeutic efficacy and reduced systemic toxicity.

STING Agonist VB-85247 Induces Durable Antitumor Immune Responses by Intravesical Administration in a Non-Muscle-Invasive Bladder Cancer

Bacillus Calmette-Guérin (BCG) is the current standard of care for non-muscle-invasive bladder cancer (NMIBC), but recurrence is common. Additional therapeutic options are a major unmet medical need for treating unresponsive patients. Stimulator of IFN genes (STING) plays a central role in mounting innate and adaptive immune responses to tumor cells, and activation of STING is a promising immunotherapeutic approach. In this study, we developed STING agonist VB-85247 for treating NMIBC by intravesical delivery as a strategy to provide a sustained period of exposure to bladder cancer cells while avoiding potential issues associated with intratumoral injection of STING agonists, which to date have shown only limited clinical efficacy. VB-85247 induced complete response in an orthotopic NMIBC model in contrast to treatment with BCG, which was not efficacious in the model. The efficacious dose was well tolerated and induced an immune response with immunologic memory that protected from rechallenge without further treatment. Activation of the STING pathway via VB-85247 induced upregulation of inflammatory cytokines IFNα/β, TNFα, IL6, and CXCL10, along with maturation and activation of dendritic cells. In addition, VB-85247 provided a therapeutic benefit in combination with immune checkpoint blockade using anti-PD-1 antibody treatment. Together, these preclinical data support the potential utility of VB-85247 for treating BCG-unresponsive patients with NMIBC and for enhancing the clinical benefit of potential of anti-PD-1 in bladder cancer. Based on these data, VB-85247 is being advanced into clinical development. Significance: STING agonist VB-85247 administered by the intravesical route achieves prolonged tumor regression, induces immunologic memory, and provides additive benefits to anti-PD-1 treatment in non-muscle invasive bladder cancer.

Intratumoral or Subcutaneous MK-2118, a Noncyclic Dinucleotide STING Agonist, with or without Pembrolizumab, for Advanced or Metastatic Solid Tumors or Lymphomas

PURPOSE

We evaluated the noncyclic dinucleotide stimulator of IFN genes agonist MK-2118 ± pembrolizumab in participants with advanced solid tumors or lymphomas.

PATIENTS AND METHODS

This first-in-human study (NCT03249792) enrolled participants with refractory, advanced solid tumors or lymphomas. Participants received intratumoral (IT) MK-2118 100 to 20,000 μg (arm 1), IT MK-2118 900 to 15,000 μg plus intravenous (IV) pembrolizumab 200 mg every 3 weeks (arm 2), or subcutaneous (SC) MK-2118 5,000 to 150,000 μg plus IV pembrolizumab 200 mg every 3 weeks (arm 4); arm 3 (visceral injection of MK-2118) was not pursued. IT dosing used an accelerated titration design and modified toxicity probability interval method; SC dosing (arm 4) was started subsequent to arms 1 and 2. The primary objectives were safety/tolerability. MK-2118 pharmacokinetics was a secondary endpoint; objective responses and biomarkers were exploratory endpoints.

RESULTS

A total of 140 participants were enrolled (arm 1, n = 27; arm 2, n = 57; arm 4, n = 56). Grade 3/4 treatment-related adverse events occurred in 22%, 23%, and 11% of participants, respectively, but no maximum tolerated dose was identified up to MK-2118 20,000, 15,000, and 150,000 μg across the three arms. Dose-dependent increases in MK-2118 systemic exposure were observed following IT and subcutaneous administration. Objective responses were seen in 0%, 6%, and 4% of participants, respectively. IT MK-2118 led to dose-dependent changes in stimulator of interferon genes-based blood RNA expression levels, IFNγ, IFNγ-induced protein 10, and IL6; SC MK-2118 did not generate dose-related immune responses.

CONCLUSIONS

IT MK-2118 ± pembrolizumab and SC MK-2118 plus pembrolizumab had manageable toxicity and limited antitumor activity. IT but not SC administration demonstrated systemic immune effects.

Enhancing immunotherapy with tumour-responsive nanomaterials

The targeted delivery of immunotherapies to tumours using tumour-responsive nanomaterials is a promising area of cancer research with the potential to address the limitations of systemic administration such as on-target off-tumour toxicities and a lack of activity owing to the immunosuppressive tumour microenvironment (TME). Attempts to address these challenges include the design and functionalization of nanomaterials capable of releasing their cargoes in response to specific TME characteristics, thus facilitating the targeted delivery of immune-checkpoint inhibitors, cytokines, mRNAs, vaccines and, potentially, chimaeric antigen receptors as well as of agents that modulate the extracellular matrix and induce immunogenic cell death. In this Review, we describe these various research efforts in the context of the dynamic properties of the TME, such as pH, reductive conditions, reactive oxygen species, hypoxia, specific enzymes, high levels of ATP and locoregional aspects, which can be leveraged to enhance the specificity and efficacy of nanomaterial-based immunotherapies. Highlighting preclinical successes and ongoing clinical trials, we evaluate the current landscape and potential of these innovative approaches. We also consider future research directions as well as the most important barriers to successful clinical translation, emphasizing the transformative potential of tumour-responsive nanomaterials in overcoming the barriers that limit the activity of traditional immunotherapies, thus improving patient outcomes.

DNA-encoded dynamic hydrogels for 3D bioprinted cartilage organoids

Articular cartilage, composed of chondrocytes within a dynamic viscoelastic matrix, has limited self-repair capacity, posing a significant challenge for regeneration. Constructing high-fidelity cartilage organoids through three-dimensional (3D) bioprinting to replicate the structure and physiological functions of cartilage is crucial for regenerative medicine, drug screening, and disease modeling. However, commonly used matrix bioinks lack reversible cross-linking and precise controllability, hindering dynamic cellular regulation. Thus, encoding bioinks adaptive for cultivating cartilage organoids is an attractive idea. DNA, with its ability to be intricately encoded and reversibly cross-linked into hydrogels, offers precise manipulation at both molecular and spatial structural levels. This endows the hydrogels with viscoelasticity, printability, cell recognition, and stimuli responsiveness. This paper elaborates on strategies to encode bioink via DNA, emphasizing the regulation of predictable dynamic properties and the resulting interactions with cell behavior. The significance of these interactions for the construction of cartilage organoids is highlighted. Finally, we discuss the challenges and future prospects of using DNA-encoded hydrogels for 3D bioprinted cartilage organoids, underscoring their potential impact on advancing biomedical applications.

Acid-Responsive Biocompatible Hydrogel Modulating Tumor DNA Self-Repair Collaborated with Chemotherapy for Boosting STING Pathway-Associated Immunotherapy

In this study, an acid-responsive hydrogel (ODCM@AZD) encapsulating doxorubicin (DOX), Mn2+, and AZD2281 is rationally engineered for synergistic chemo-immunotherapy. Notably, ODCM@AZD can be specifically degraded within the tumor microenvironment to release the loaded therapeutic agents. Specifically, the released DOX kills tumor cells to produce abundant cytoplasmic DNA, while the freed AZD2281 inhibits the DNA repair pathway of tumor cells to enhance the chemotherapeutic effect and promote the accumulation of damaged DNA, which is further aggravated by reactive oxygen species (ROS) generated from the Mn2+-mediated Fenton-like reaction. Not only that, Mn2+ simultaneously increases the sensitivity of cGAS to cytoplasmic DNA to stimulate the cGAS-STING pathway and synergizes with DOX-mediated immunogenic cell death (ICD) to initiate powerful antitumor immune responses. More importantly, the combination of ODCM@AZD with immune checkpoint blockade (ICB) significantly improves systemic tumoricidal immunity and potentiates therapeutic effects on distant and recurrent tumor models, providing a new idea for antitumor chemo-immunotherapy.

MnO2@CeOx-GAMP radiosensitizer with oxygen vacancies depended mimicking enzyme-like activities for radiosensitization-mediated STING pathway activation

Activation of the stimulator of interferon genes (STING) pathway by radiotherapy (RT) has a significant effect on eliciting antitumor immune responses. The generation of hydroxyl radical (·OH) storm and the sensitization of STING-relative catalytic reactions could improve radiosensitization-mediated STING activation. Herein, multi-functional radiosensitizer with oxygen vacancies depended mimicking enzyme-like activities was fabricated to produce more dsDNA which benefits intracellular 2', 3'-cyclic GMP-AMP (cGAMP) generation, together with introducing exogenous cGAMP to activate immune response. MnO2@CeOx nanozymes present enhanced superoxide dismutase (SOD)-like and peroxidase (POD)-like activities due to induced oxygen vacancies accelerate the redox cycles from Ce4+ to Ce3+ via intermetallic charge transfer. CeOx shells not only serve as radiosensitizer, but also provide the conjugation site for AMP/GMP to form MnO2@CeOx-GAMP (MCG). Upon X-ray irradiation, MCG with SOD-like activity facilitates the conversion of superoxide anions generated by Ce-sensitization into H2O2 within tumor microenvironment (TME). The downstream POD-like activity catalyzes the elevated H2O2 into a profusion of ·OH for producing more damage DNA fragments. TME-responsive decomposed MCG could supply exogenous cGAMP, meanwhile the releasing Mn2+ improve the sensitivity of cyclic GMP-AMP synthase to dsDNA for producing more cGAMP, resulting in the promotion of STING pathway activation.

MAVS: The next STING in cancers and other diseases

The mitochondrial antiviral signaling protein (MAVS) is a pivotal adaptor in the antiviral innate immune signaling pathway and plays a crucial role in the activation of antiviral defences. This comprehensive review delves into the multifaceted functions of MAVS, spanning from its integral role in the RIG-I-like receptor (RLR) pathway to its emerging roles in tumor biology and autoimmune diseases. We discuss the structural and functional aspects of MAVS, its activation mechanisms, and the intricate regulatory networks that govern its activity. The potential of MAVS as a therapeutic target has been explored, highlighting its promise in personalized cancer therapy and developing combination treatment strategies. Additionally, we compare it with the STING signaling pathway and discuss the synergistic potential of targeting both pathways in immunotherapy. Our review underscores the importance of MAVS in maintaining immune homeostasis and its implications for a broad spectrum of diseases, offering new avenues for therapeutic intervention.

Utilizing Nanoparticles to Overcome Anti-PD-1/PD-L1 Immunotherapy Resistance in Non-Small Cell Lung cancer: A Potential Strategy

Lung cancer is the leading cause of cancer-related mortality globally, with non-small cell lung cancer (NSCLC) constituting 85% of cases. Immune checkpoint inhibitors (ICIs) represented by anti-programmed cell death protein 1 (PD-1)/ programmed cell death ligand 1 (PD-L1) have emerged as a promising frontier in cancer treatment, effectively extending the survival of patients with NSCLC. However, the efficacy of ICIs exhibits significant variability across diverse patient populations, with a substantial proportion showing poor responsiveness and acquired resistance in those initially responsive to ICIs treatments. With the advancement of nanotechnology, nanoparticles offer unique advantages in tumor immunotherapy, including high permeability and prolonged retention(EPR) effects, enhanced drug delivery and stability, and modulation of the inflammatory tumor microenvironment(TME). This review summarizes the mechanisms of resistance to ICIs in NSCLC, focusing on tumor antigens loss and defective antigen processing and presentation, failure T cell priming, impaired T cell migration and infiltration, immunosuppressive TME, and genetic mutations. Furthermore, we discuss how nanoparticles, through their intrinsic properties such as the EPR effect, active targeting effect, shielding effect, self-regulatory effect, and synergistic effect, can potentiate the efficacy of ICIs and reverse resistance. In conclusion, nanoparticles serve as a robust platform for ICIs-based NSCLC therapy, aiding in overcoming resistance challenges.

Cytosolic DNA composition is determined by genomic instability mechanism and regulates dendritic cell-mediated anti-tumor immunity

Patients with colorectal cancers (CRCs) that have microsatellite instability (MSI) (MSI CRCs) face a better prognosis than those with the more common chromosomal instability (CIN) subtype (CIN CRCs) due to improved T cell-mediated anti-tumor immune responses. Previous investigations identified the cytosolic DNA (cyDNA) sensor STING as necessary for chemokine-mediated T cell recruitment in MSI CRCs. Here, we find that cyDNA from MSI CRC cells is inherently more capable of inducing STING activation and improves cytotoxic T cell activation by dendritic cells (DCs). Sequencing indicates that MSI cyDNA is enriched in microsatellites, which, upon DC uptake, induce anti-tumor immunity in a manner consistent with clinical MSI CRCs. DNA-damaging therapies also modulate cyDNA stimulation capacity, with radiation inducing larger cyDNA sizes and increased mitochondrial DNA content. Identifying highly stimulatory endogenous cyDNAs such as those in MSI CRCs will allow for optimized development of DNA-based STING agonist therapies to improve the responses of CIN CRCs with CIN to immunotherapies.

Intrinsic STING of CD8 + T cells regulates self-metabolic reprogramming and memory to exert anti-tumor effects

BACKGROUND

Our team has previously found that the stimulator of interferon genes (STING) plays a more significant anti-tumor role in host immune cells than in tumor cells. Although STING is necessary for CD8 + T cells to exert immunological activity, its effect on CD8 + T cells remains debatable. In this study, we used both in vitro and in vivo models to explore the metabolic effects of STING on CD8 + T cells.

METHODS

Peripheral blood lymphocytes were procured from non-small cell lung cancer (NSCLC) patients receiving anti-PD-1 therapy to investigate the correlation between STING expression levels, CD8 + T-cell subsets, and immunotherapy efficacy. STING knockout (STING-KO) mice were used for in vivo studies. RNA-seq, seahorse, flow cytometry, electron microscopy, qPCR, immunofluorescence, western blotting, and immunoprecipitation were performed to explore the underlying mechanisms of STING in regulating CD8 + T cell function.

RESULTS

We discovered that the expression level of STING in immune cells exhibited a significant correlation with immunotherapy efficacy, as well as with the proportion of central memory CD8 + T cells. Moreover, we found that the loss of the STING gene results in a reduction in the number of mitochondria and a change in the metabolic pathway selection, thereby inducing excessive glycolysis in CD8 + T cells. This excessive glycolysis generates high levels of lactate, which further inhibits IFN-γ secretion and impacts memory T cell differentiation. Correcting the glycolysis disorder partially restored function and IFN-γ secretion, rescued the central memory CD8 + T subset, and improved immunotherapy in STING-KO mice. This provides a new treatment strategy for patients with low STING expression and a poor response to immunotherapy.

CONCLUSION

Intrinsic STING of CD8 + T cells affects their function through the HK2/Lactate/IFN-γ axis and affects memory differentiation by regulating glycolysis.

Activating the cGAS-STING Pathway by Manganese-Based Nanoparticles Combined with Platinum-Based Nanoparticles for Enhanced Ovarian Cancer Immunotherapy

Recent research has demonstrated that activating the cGAS-STING pathway can enhance interferon production and the activation of T cells. A manganese complex, called TPA-Mn, was developed in this context. The reactive oxygen species (ROS)-sensitive nanoparticles (NPMn) loaded with TPA-Mn are developed. NPMn activates the cGAS-STING pathway via cGAS activation (i.e., 1.6-fold enhancement of P-STING), which in turn increases the secretion of pro-inflammatory cytokines (e.g., TNF-α, IL-6, and IL-2). This promotes dendritic cell maturation, enhances the infiltration of cytotoxic T lymphocytes, and reduces the percentage of immunosuppressive regulatory T cells. In addition, it is crucial to emphasize that cisplatin-induced DNA damage can potentially trigger activation of the cGAS-STING pathway. NPMn, in combination with low-dose NPPt, a carrier of a Cis(IV) prodrug capable of causing DNA damage, augments the cGAS-STING pathway activation and significantly activates the tumor immune microenvironment (TIME). Furthermore, combined with anti-PD-1 antibody, NPPt+NPMn shows synergistic efficacy in both ovarian cancer peritoneal metastases and recurrence models. It not only effectively eliminates tumors but also induces a strong immune memory response, providing a promising strategy for the clinical management of ovarian cancer. This work offers a design of manganese-based nanoparticles for immunotherapy.

Platinum(IV)-Backboned Polymer Prodrug-Functionalized Manganese Oxide Nanoparticles for Enhanced Lung Cancer Chemoimmunotherapy via Amplifying Stimulator of Interferon Genes Activation

The stimulator of interferon genes (STING) pathway exhibits great potential in remodeling the immunosuppressive tumor microenvironment and initiating antitumor immunity. However, how to effectively activate STING and avoid undesired toxicity after systemic administration remains challenging. Herein, platinum(IV)-backboned polymer prodrug-coated manganese oxide nanoparticles (DHP/MnO2NP) with pH/redox dual responsive properties are developed to precisely release cisplatin and Mn2+ in the tumor microenvironment and synergistically amplify STING activation. In vitro, we demonstrate that DHP/MnO2NP can effectively induce tumor cell DNA damage and leak into the cytoplasm, cooperating with Mn2+ to promote STING activation and significantly upregulate the expression of proinflammatory cytokines. Additionally, DHP/MnO2NP can selectively release cisplatin and Mn2+ to mediate tumor killing while reducing toxicity to normal cells. In vivo, DHP/MnO2NP exerted increased therapeutic efficacy by inducing STING activation and initiating robust antitumor immunity. Specifically, DHP/MnO2NP effectively skewed tumor-associated macrophages toward a proinflammatory phenotype and upregulated the expression of proinflammatory cytokines in tumors by up to 99-fold relative to the control. And the infiltration of CD8+ T cells was also significantly increased. When STING signaling was blocked, the antitumor effects and immunostimulatory efficacy of DHP/MnO2NP were significantly inhibited. Moreover, DHP/MnO2NP possess the advantage of enhanced tumor homing and retention, resulting in stronger and longer-lasting anticancer effects. Overall, DHP/MnO2NP provide a potential platform for potentiating cancer chemoimmunotherapy and hold promise for precision treatment.

Endothelial STING-JAK1 interaction promotes tumor vasculature normalization and antitumor immunity

Stimulator of interferon genes (STING) agonists have been developed and tested in clinical trials for their antitumor activity. However, the specific cell population(s) responsible for such STING activation-induced antitumor immunity have not been completely understood. In this study, we demonstrated that endothelial STING expression was critical for STING agonist-induced antitumor activity. STING activation in endothelium promoted vessel normalization and CD8+ T cell infiltration - which required type I IFN (IFN-I) signaling- but not IFN-γ or CD4+ T cells. Rather than an upstream adaptor for inducing IFN-I signaling, STING acted downstream of interferon-α/β receptor (IFNAR) in endothelium for the JAK1-STAT signaling activation. Mechanistically, IFN-I stimulation induced JAK1-STING interaction and promoted JAK1 phosphorylation, which involved STING palmitoylation at the Cysteine 91 site but not its C-terminal tail (CTT) domain. Endothelial STING and JAK1 expression was significantly associated with immune cell infiltration in patients with cancer, and STING palmitoylation level correlated positively with CD8+ T cell infiltration around STING-positive blood vessels in tumor tissues from patients with melanoma. In summary, our findings uncover a previously unrecognized function of STING in regulating JAK1/STAT activation downstream of IFN-I stimulation and provide a new insight for future design and clinical application of STING agonists for cancer therapy.

Engineering Autologous Cell-Derived Exosomes to Boost Melanoma-Targeted Radio-Immunotherapy by Cascade cGAS-STING Pathway Activation

Radio-immunotherapy has offered emerging opportunities to treat invasive melanoma due to its immunostimulatory performances to activate antitumor immune responses. However, the immunosuppressive microenvironment and insufficient response rate significantly limit the practical efficacy. This study presents an autologous cell-derived exosomes (Exo)-engineered nanoagonist (MnExo@cGAMP) containing with metalloimmunotherapeutic agent (Mn2+ ions) and nucleotidyltransferase (2',3'-cGAMP, a STING agonist) for boosting melanoma-targeted radio-immunotherapy by cascade cGAS-STING pathway activation. The MnExo@cGAMP can efficiently accumulate in tumor cells due to the autologous targeting performance. Once internalized by tumor cells, the released Mn2+ ions will enhance stimulator of interferon gene (STING) binding and sensitize cyclic GMP-AMP (cGAS) to radiotherapy-induced double-straned DNA (dsNDA), resulting in amplification of cGAS-STING pathway activation together with X-ray irradiation. Meanwhile, loaded 2',3'-cGAMP can directly augment pathway activity acting as a secondary messenger. These cascade activations of cGAS-STING pathway trigger the overexpression of type I interferon, promote dendritic cells (DCs) maturation, antigen presentation, and increase CD8+ T cell activation, resulting effective radio-immunotherapeutic outcome by overcoming immune-suppression in melanoma. This study demonstrates a targeted therapeutic modality involving metalloimmunotherapy and agonist for efficient melanoma radio-immunotherapy by cascade cGAS-STING pathway activation.

Enhanced Tumor Immunotherapy by Triple Amplification Effects of Nanomedicine on the STING Signaling Pathway in Dendritic Cells

Insufficient activation of stimulator of interferon genes (STING) signaling pathway in tumor-associated dendritic cells limits the efficiency of tumor immunotherapy. Herein, the "three-in-one" IAHA-LaP/siPTPN6 NPs containing lanthanum ions (La3+), cGAMP, and PTPN6 siRNA are developed for triple amplification of the STING pathway. In vitro results demonstrate that La3+ significantly promotes cGAMP-mediated activation of the STING pathway by enhancing the phosphorylation of STING, TBK1, IRF3, and NF-κB p65. Moreover, the IAHA-LaP/siPTPN6 NPs further significantly enhance the phosphorylation of STING and NF-κB p65 and augment K63-linked ubiquitination of STING protein via siPTPN6-mediated downregulation of SHP-1 protein. Furthermore, NPs improve the secretion of IFNβ (2.4-fold), IL-6 (1.5-fold), and TNF-α (1.4-fold), thereby promoting DCs maturation compared to the mixture of La3+ and cGAMP. In vivo results show that the IAHA-LaP/siPTPN6 NPs remarkably inhibit primary tumor growth by increasing the percentage of mature DCs in tumor-draining lymph nodes, polarizing M2/M1 phenotype in TME, and promoting the infiltration of CD8+T cells into tumors. Moreover, these NPs dramatically prevent the growth of distal tumor by inducing systemic anti-tumor immunity and generating a long-term anti-tumor memory for protection against tumor recurrence in mice bearing bilateral B16F10. These IAHA-LaP/siPTPN6 NPs may offer a promising platform for robust anti-tumor immune responses.

Cytosolic bacterial pathogens activate TLR pathways in tumors that synergistically enhance STING agonist cancer therapies

Intracellular bacterial pathogens are distinctive tools for fighting cancer, as they can proliferate in tumors and deliver therapeutic payloads to the eukaryotic cytosol. Cytosol-dwelling bacteria have undergone extensive preclinical and clinical testing, yet the mechanisms of activating innate immunity in tumors are unclear. We report that phylogenetically distinct cytosolic pathogens, including Listeria, Rickettsia, and Burkholderia species, elicited anti-tumor responses in poorly immunogenic melanoma and lymphoma in mice. Although the bacteria required cytosolic access, anti-tumor responses were largely independent of the cytosolic sensors cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING), but instead required Toll-like receptor (TLR) signaling. Combining pathogens with STING agonists elicited profound, synergistic anti-tumor effects with complete responses in >80% of mice. Small molecule TLR agonists also synergistically enhanced STING agonists. The responses required RAG2 but not interferons, and cured mice developed immunity to cancer rechallenge requiring CD8+ T cells. These studies provide a framework for enhancing microbial and small molecule innate agonists for cancer, via co-activating STING and TLRs.

Integration of STING activation and COX-2 inhibition via steric-hindrance effect tuned nanoreactors for cancer chemoimmunotherapy

Integrating immunotherapy with nanomaterials-based chemotherapy presents a promising avenue for amplifying antitumor outcomes. Nevertheless, the suppressive tumor immune microenvironment (TIME) and the upregulation of cyclooxygenase-2 (COX-2) induced by chemotherapy can hinder the efficacy of the chemoimmunotherapy. This study presents a TIME-reshaping strategy by developing a steric-hindrance effect tuned zinc-based metal-organic framework (MOF), designated as CZFNPs. This nanoreactor is engineered by in situ loading of the COX-2 inhibitor, C-phycocyanin (CPC), into the framework building blocks, while simultaneously weakening the stability of the MOF. Consequently, CZFNPs achieve rapid pH-responsive release of zinc ions (Zn2+) and CPC upon specific transport to tumor cells overexpressing folate receptors. Accordingly, Zn2+ can induce reactive oxygen species (ROS)-mediated cytotoxicity therapy while synchronize with mitochondrial DNA (mtDNA) release, which stimulates mtDNA/cGAS-STING pathway-mediated innate immunity. The CPC suppresses the chemotherapy-induced overexpression of COX-2, thus cooperatively reprogramming the suppressive TIME and boosting the antitumor immune response. In xenograft tumor models, the CZFNPs system effectively modulates STING and COX-2 expression, converting "cold" tumors into "hot" tumors, thereby resulting in ≈ 4-fold tumor regression relative to ZIF-8 treatment alone. This approach offers a potent strategy for enhancing the efficacy of combined nanomaterial-based chemotherapy and immunotherapy.

Cooperative tumor inhibition by CpG-oligodeoxynucleotide and cyclic dinucleotide in head and neck cancer involves T helper cytokine and macrophage phenotype reprogramming

Head and neck cancer ranks as the sixth most common cancer worldwide, highlighting the critical need for the development of new therapies to enhance treatment efficacy. The activation of innate immune receptors given their potent immune stimulatory properties aid in the eradication of cancer cells. In this study, we investigated the immune mechanism and anti-tumor function of a Toll-like receptor 9 (TLR9) agonist, CpG-oligodeoxynucleotide-2722 (CpG-2722), in combination with cyclic dinucleotides, which are agonists of stimulator of interferon genes (STING). Our results revealed that CpG-2722 stimulation increased the expression of Th1 pro-inflammatory cytokines. Stimulation by STING agonists exhibited lower expression of Th1 cytokines but higher expression of Th2 cytokines compared to CpG-2722. However, the combination of these two agonists significantly enhanced Th1 cytokines while reducing Th2 cytokines. Moreover, in vivo experiment showed that both CpG-2722 and 2'3'-c-di-AMP suppressed head and neck tumor growth, with their combination proving more effective than the use of these agonists alone. The combined treatment cooperatively promoted the production of Th1 cytokines and type I interferons, while suppressing Th2 cytokines in the tumors as observed in vitro. Additionally, it led to the accumulation of M1 macrophages, dendritic cells, and T cells, shaping a favorable tumor microenvironment for T cell-mediated tumor killing. The anti-tumor activity of the CpG-2722 and 2'3'-c-di-AMP combination depends on the macrophage presence but does not directly activate M1 macrophage polarization, instead working through a reprogrammed cytokine profile. Furthermore, this combination shows a cooperative anti-tumor activity with anti-PD-1 in treating head and neck tumors. Overall, these findings highlight a Th response and macrophage phenotype reprograming involved functional mechanism underlying the cooperative activity of the combination of TLR9 and STING agonists in the immunotherapy of head and neck cancer.

Unraveling the cGAS/STING signaling mechanism: impact on glycerolipid metabolism and diseases

The cyclic GMP-AMP synthase (cGAS) and its downstream effector, the stimulator of interferon genes (STING), are crucial components of the innate immune response, traditionally recognized for their role in detecting cytosolic DNA from pathogens and damaged host cells. However, recent research indicates that the cGAS-STING pathway also significantly impacts metabolic processes, particularly glycerolipid metabolism. Glycerolipids are essential for energy storage and cellular membrane integrity, and their dysregulation is linked to metabolic disorders such as obesity, insulin resistance, and non-alcoholic fatty liver disease (NAFLD). Both cGAS and STING are expressed in various metabolic tissues, suggesting a potential role in lipid homeostasis. Chronic activation of the cGAS-STING pathway may promote inflammatory states that exacerbate insulin resistance and lipid accumulation, forming a feedback loop of metabolic dysfunction. This review explores the emerging relationship between cGAS/STING signaling and glycerolipid metabolism, discussing the mechanisms through which this pathway influences lipid regulation and the potential for therapeutic interventions. By integrating insights from immunology and metabolism, we aim to provide a comprehensive understanding of how the cGAS-STING axis may serve as a novel target for addressing metabolic disorders and enhancing metabolic health outcomes.

Macrophage crosstalk and therapies: Between tumor cells and immune cells

In the tumor microenvironment, macrophages exhibit different phenotypes and functions in response to various signals, playing a crucial role in the initiation and progression of tumors. Several studies have indicated that intervention in the functions of different phenotypes of tumor-associated macrophages causes significant changes in the crosstalk between tumor cells and immune-related cells, such as T, NK, and B cells, markedly altering the course of tumor development. However, only a few specific therapeutic strategies targeting macrophages are yet available. This article comprehensively reviews the molecular biology mechanisms through which tumor-associated macrophages mediate the crosstalk between tumor cells and immune-related cells. Also, various treatment methods currently used in clinical practice and those in the clinical trial phase have been summarized, and the novel strategies for targeting tumor-associated macrophages have been categorized accordingly.

STING agonists and PI3Kγ inhibitor co-loaded ferric ion-punicalagin networks for comprehensive cancer therapy

Nanoparticles-based drug delivery system has been a promising approach for the treatment of colorectal cancer (CRC), which can be combined with chemotherapy, targeted therapy and immunotherapy to improve the treatment of CRC. 2'3' cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) is an agonist of the STING signaling pathway activating antitumor immunity. IPI-549 is a small-molecule inhibitor for phosphatidylinositol 3-kinase γ (PI3Kγ), which can induce M1 macrophages polarization to provide pro-inflammatory microenvironment to suppress tumors. Here, we developed a ferric ion-punicalagin network (Fe-PU), which can be not only used as an inducer of ferroptosis, but also serve as a carrier to load cGAMP and IPI-549 to obtain nanohybrid (Fe-PU/CD-IPI). In order to improve the delivery effect and targeted ability to CRC, a cyclic arginine-glycine-aspartic acid peptide linked-bovine serum albumin were utilized to modify Fe-PU/CD-IPI to prepare nanohybrid Fe-PU/CD-IPI@cBSA. The therapeutic effect of various nanohybrids were validated in the mice with spontaneous tumor in the colorectal area and tumor-bearing mice, which lead to the increase of ferroptosis, the activation of STING signaling pathway, and the repolarization of macrophages. Collectively, the cGAMP and IPI-549 co-loaded nanohybrids effectively reshaped the tumor immune microenvironment, and exhibited prominent treatment effect of anti-colorectal cancer in vitro, patient-derived organoids, and in vivo.

Implications of the cGAS-STING pathway in diabetes: Risk factors and therapeutic strategies

Diabetes mellitus is an increasingly prevalent metabolic disorder characterized by chronic hyperglycemia and impaired insulin action. Although the pathogenesis of diabetes is multifactorial, emerging evidence suggests that chronic low-grade inflammation plays a significant role in the development and progression of the disease. The cyclic GMP-AMP synthase (cGAS) and its downstream signaling pathway, the stimulator of interferon genes (STING), have recently gained attention in the field of diabetes research. This article aims to provide an overview of the role of cGAS-STING in diabetes, focusing on its involvement in the regulation of immune responses, inflammation, insulin resistance, and β-cell dysfunction. Understanding the contribution of cGAS-STING signaling in diabetes may lead to the development of targeted therapeutic strategies for this prevalent metabolic disorder. The results section presents key findings from multiple studies on the impact of STING in diabetes. It discusses the influence of STING on inflammation levels within a diabetic environment, its effect on insulin resistance, and its implications for the development and progression of diabetes. The cGAS-STING signaling pathway plays a crucial role in the development and progression of diabetes.

Toxicity and efficacy of type I interferons on the ocular surface: in vitro, animal, and clinical studies

PURPOSE

To investigate the toxicity of type I interferons (IFNs) on the ocular surface and assess their efficacy in ocular surface tumors.

METHODS

We examined the effects of IFN-α2a, IFN-α2b and IFN-β on corneal epithelial cells and stromal fibroblasts in vitro as well as the impact of IFN-α2a on the ocular surface in mice. Additionally, we analyzed the therapeutic and adverse effects of topically administered IFN-α2a and IFN-α2b in patients with ocular surface tumors. Risk factors contributing to side effects were explored.

RESULTS

IFN-α2a, IFN-α2b or IFN-β reduced cell viability and induced pro-inflammatory cytokines in corneal epithelial cells and stromal fibroblasts. Furthermore, IFNs enhanced the expression of major histocompatibility complex class II and CD40 in corneal epithelial cells. In mice, subconjunctival IFN-α2a injection did not induce corneal epithelial defects or opacity, nor did it reduce aqueous tears or conjunctival goblet cells. In patients, topical IFN-α2a or IFN-α2b administration decreased tumor size and prevented recurrence; however, it was associated with mild side effects, including corneal epitheliopathy and conjunctival hyperemia. These complications were associated with longer IFN use, the presence of underlying ocular surface disease and concurrent use of mitomycin C or anti-glaucoma eye drops.

CONCLUSION

Although type I IFNs cause direct toxicity on corneal cells, they do not induce significant side effects on the healthy ocular surface. Considering its therapeutic and preventive effects, topical type I IFN is safe and effective for treating ocular surface tumors. The potential for ocular side effects should be considered in eyes with identified risk factors.

Self-assembly of a ruthenium-based cGAS-STING photoactivator for carrier-free cancer immunotherapy

The cGAS (cyclic GMP-AMP synthase)-STING (stimulator of interferon genes) pathway promotes antitumor immune responses by sensing cytosolic DNA fragments leaked from nucleus and mitochondria. Herein, we designed a highly charged ruthenium photosensitizer (Ru1) with a β-carboline alkaloid derivative as the ligand for photo-activating of the cGAS-STING pathway. Due to the formation of multiple non-covalent intermolecular interactions, Ru1 can self-assemble into carrier-free nanoparticles (NPs). By incorporating the triphenylphosphine substituents, Ru1 can target and photo-damage mitochondrial DNA (mtDNA) to cause the cytoplasmic DNA leakage to activate the cGAS-STING pathway. Finally, Ru1 NPs show potent antitumor effects and elicit intense immune responses in vivo. In conclusion, we report the first self-assembling mtDNA-targeted photosensitizer, which can effectively activate the cGAS-STING pathway, thus providing innovations for the design of new photo-immunotherapeutic agents.

Inactivated cGAS-STING Signaling Facilitates Endocrine Resistance by Forming a Positive Feedback Loop with AKT Kinase in ER+HER2- Breast Cancer

Endocrine-resistant ER+HER2- breast cancer (BC) is particularly aggressive and leads to poor clinical outcomes. Effective therapeutic strategies against endocrine-resistant BC remain elusive. Here, analysis of the RNA-sequencing data from ER+HER2- BC patients receiving neoadjuvant endocrine therapy and spatial transcriptomics analysis both show the downregulation of innate immune signaling sensing cytosolic DNA, which primarily occurs in endocrine-resistant BC cells, not immune cells. Indeed, compared with endocrine-sensitive BC cells, the activity of sensing cytosolic DNA through the cGAS-STING pathway is attenuated in endocrine-resistant BC cells. Screening of kinase inhibitor library show that this effect is mainly mediated by hyperactivation of AKT1 kinase, which binds to kinase domain of TBK1, preventing the formation of a trimeric complex TBK1/STING/IRF3. Notably, inactivation of cGAS-STING signaling forms a positive feedback loop with hyperactivated AKT1 to promote endocrine resistance, which is physiologically important and clinically relevant in patients with ER+HER2- BC. Blocking the positive feedback loop using the combination of an AKT1 inhibitor with a STING agonist results in the engagement of innate and adaptive immune signaling and impairs the growth of endocrine-resistant tumors in humanized mice models, providing a potential strategy for treating patients with endocrine-resistant BC.

Tumor phagocytosis-driven STING activation invigorates antitumor immunity and reprograms the tumor micro-environment

Immunogenic cell death (ICD) holds the potential for in situ tumor vaccination while concurrently eradicating tumors and stimulating adaptive immunity. Most ICD inducers, however, elicit insufficient immune responses due to negative feedback against ICD biomarkers, limited infiltration of antitumoral immune cells, and the immunosuppressive tumor micro-environment (TME). Recent findings highlight the pivotal roles of stimulators of interferon gene (STING) activation, particularly in stimulating antigen-presenting cells (APCs) and TME reprogramming, addressing ICD limitations. Herein, we introduced 'tumor phagocytosis-driven STING activation', which involves the activation of STING in APCs during the recognition of ICD-induced cancer cells. We developed a polypeptide-based nanocarrier encapsulating both doxorubicin (DOX) and diABZI STING agonist 3 (dSA3) to facilitate this hypothesis in vitro and in vivo. After systemic administration, nanoparticles predominantly accumulated in tumor tissue and significantly enhanced anticancer efficacy by activating tumor phagocytosis-driven STING activation in MC38 and TC1 tumor models. Immunological activation of APCs occurred within 12 h, subsequently leading to the activation of T cells within 7 days, observed in both the TME and spleen. Furthermore, surface modification of nanoparticles with cyclic RGD (cRGD) moieties, which actively target integrin αvβ3, enhances tumor accumulation and eradication, thereby verifying the establishment of systemic immune memory. Collectively, this study proposes the concept of tumor phagocytosis-driven STING activation and its effectiveness in generating short-term and long-term immune responses.

Lipo/TK-CDN/TPP/Y6 nanoparticles inhibit cutaneous melanoma formation

Stimulation of the innate immune stimulator of interferon genes (STING) pathway has been shown to boost anti-tumour immunity. Nevertheless, the systemic delivery of STING agonists to the tumour presents challenges. Therefore, we designed a cyclic dinucleotide (CDN)-based drug delivery system (DDS) combined photothermal therapy (PTT)/photodynamic therapy (PDT)/immunotherapy for cutaneous melanoma. We coencapsulated a reactive oxygen species (ROS)-responsive prodrug thioketone-linked CDN (TK-CDN), and photoresponsive agents chlorin E6 (Y6) within mitochondria-targeting reagent triphenylphosphonium (TPP)-modified liposomes (Lipo/TK-CDN/TPP/Y6). Lipo/TK-CDN/TPP/Y6 exhibited a photothermal effect similar to Y6, along with a superior cellular uptake rate. Upon endocytosis by B16F10 cells, Lipo/TK-CDN/TPP/Y6 generated large amounts of ROS under laser irradiation for PDT. Mice bearing B16F10 tumours were intravenously injected with Lipo/TK-CDN/TPP/Y6 and exposed to irradiation, resulting in a substantial inhibition of tumour growth. Exploration of the mechanism of anti-tumour action showed that Lipo/TK-CDN/TPP/Y6 had a stronger stimulation of STING activation and anti-tumour immune cell infiltration compared to other groups. Hence, the Lipo/TK-CDN/TPP/Y6 nanoparticles offer great potential as a DDS for targeted and on-demand drug release at tumour sites. These nanoparticles exhibit promise as a candidate for precise and controllable combination therapy in the treatment of tumours.

Delivery of a STING Agonist Using Lipid Nanoparticles Inhibits Pancreatic Cancer Growth

Introduction

The tumor microenvironment (TME) of pancreatic cancer is highly immunosuppressive and characterized by a large number of cancer-associated fibroblasts, myeloid-derived suppressor cells, and regulatory T cells. Stimulator of interferon genes (STING) is an endoplasmic reticulum receptor that plays a critical role in immunity. STING agonists have demonstrated the ability to inflame the TME, reduce tumor burden, and confer anti-tumor activity in mouse models. 2'3' cyclic guanosine monophosphate adenosine monophosphate (2'3'-cGAMP) is a high-affinity endogenous ligand of STING. However, delivering cGAMP to antigen-presenting cells and tumor cells within the cytosol remains challenging due to membrane impermeability and poor stability.

Methods

In this study, we encapsulated 2'3'-cGAMP in a lipid nanoparticle (cGAMP-LNP) designed for efficient cellular delivery. We assessed the properties of the nanoparticles using a series of in-vitro studies designed to evaluate their cellular uptake, cytosolic release, and minimal cytotoxicity. Furthermore, we examined the nanoparticle's anti-tumor effect in a syngeneic mouse model of pancreatic cancer.

Results

The lipid platform significantly increased the cellular uptake of 2'3'-cGAMP. cGAMP-LNP exhibited promising antitumor activity in the syngeneic mouse model of pancreatic cancer.

Discussion

The LNP platform shows promise for delivering exogenous 2'3'-cGAMP or its derivatives in cancer therapy.

diABZI and poly(I:C) inhibit osteoclastic bone resorption by inducing IRF7 and IFIT3

Type I interferons (IFN-I) are pleiotropic factors endowed with multiple activities that play important roles in innate and adaptive immunity. Although many studies indicate that IFN-I inducers exert favorable effects on broad-spectrum antivirus, immunomodulation, and anti-tumor activities by inducing endogenous IFN-I and IFN-stimulated genes, their function in bone homeostasis still needs further exploration. Here, our study demonstrates 2 distinct IFN-I inducers, diABZI and poly(I:C), as potential therapeutics to alleviate osteolysis and osteoporosis. First, IFN-I inducers suppress the genes that control osteoclast (OC) differentiation and activity in vitro. Moreover, diABZI alleviates bone loss in Ti particle-induced osteolysis and ovariectomized -induced osteoporosis in vivo by inhibiting OC differentiation and function. In addition, the inhibitory effects of IFN-I inducers on OC differentiation are not observed in macrophages derived from Ifnar1-/-mice, which indicate that the suppressive effect of IFN-I inducers on OC is IFNAR-dependent. Mechanistically, RNAi-mediated silencing of IRF7 and IFIT3 in OC precursors impairs the suppressive effect of the IFN-I inducers on OC differentiation. Taken together, these results demonstrate that IFN-I inducers play a protective role in bone turnover by limiting osteoclastogenesis and bone resorption through the induction of OC-specific mediators via the IFN-I signaling pathway.

Proteasome inhibitors FHND6091 enhance the ability of NK cells to kill tumor cells through multiple mechanisms

The immune system has a strong connection to tumors. When a tumor cell is recognized as an abnormal cell by the immune system, the immune system may initiate an immune response to kill the tumor cell. In this study, RNA sequencing was performed on multiple myeloma (MM) cells treated with the proteasome inhibitor FHND6091. The transcriptional changes induced by FHND6091 in RPMI8226 cells aligned notably with immune response activation and results indicated upregulation of cGAS-STING pathway-related genes in the FHND6091-treated group. In vivo and in vitro experiments had demonstrated that FHND6091 stimulated the immunoreaction of MM cells via activation of the cyclic guanosine monophosphate-adenosine synthase/stimulator of interferon genes (cGAS-STING) pathway. This activation resulted in the generation of type-I interferons and the mobilization of natural killer (NK) cells. Notably, FHND6091 upregulated the levels of calreticulin and the protein ligands UL16-binding protein 2/5/6, MHC class I chain-related A (MICA), and MICB on the surface of MM cells. Subsequently, upon engaging with the surface activation receptors of NK cells, these ligands triggered NK cell activation, leading to the subsequent elimination of tumor cells. Thus, our findings elucidated the mechanism whereby FHND6091 exerted its immunotherapeutic activity as a STING agonist, enhancing the killing ability of NK cells against tumor cells.

Microbe-material hybrids for therapeutic applications

As natural living substances, microorganisms have emerged as useful resources in medicine for creating microbe-material hybrids ranging from nano to macro dimensions. The engineering of microbe-involved nanomedicine capitalizes on the distinctive physiological attributes of microbes, particularly their intrinsic "living" properties such as hypoxia tendency and oxygen production capabilities. Exploiting these remarkable characteristics in combination with other functional materials or molecules enables synergistic enhancements that hold tremendous promise for improved drug delivery, site-specific therapy, and enhanced monitoring of treatment outcomes, presenting substantial opportunities for amplifying the efficacy of disease treatments. This comprehensive review outlines the microorganisms and microbial derivatives used in biomedicine and their specific advantages for therapeutic application. In addition, we delineate the fundamental strategies and mechanisms employed for constructing microbe-material hybrids. The diverse biomedical applications of the constructed microbe-material hybrids, encompassing bioimaging, anti-tumor, anti-bacteria, anti-inflammation and other diseases therapy are exhaustively illustrated. We also discuss the current challenges and prospects associated with the clinical translation of microbe-material hybrid platforms. Therefore, the unique versatility and potential exhibited by microbe-material hybrids position them as promising candidates for the development of next-generation nanomedicine and biomaterials with unique theranostic properties and functionalities.

Activated STING-containing R-EVs from iPSC-derived MSCs promote antitumor immunity

We recently revealed that activated STING is secreted into RAB22A-induced extracellular vesicles (R-EVs) and promotes antitumor immunity in cancer cells. Whether mesenchymal stem cell (MSC)-derived R-EVs containing activated STING can be used as a novel antitumor immunotherapy remains unclear, as MSC-derived EVs are promising cell-free therapeutics due to their superior biocompatibility and safety, as well as low immunogenicity. Here, we report that induced pluripotent stem cell (iPSC)-derived MSCs can generate R-EVs with a size and mechanism of formation that are similar to those of R-EVs produced from cancer cells. Furthermore, these MSC-derived R-EVs containing activated STING induced IFNβ expression in recipient THP-1 monocytes and antitumor immunity in mice. Our findings reveal that the use of MSC-derived R-EVs containing activated STING is a promising cell-free strategy for antitumor immunity.

Schisandrin C enhances type I IFN response activation to reduce tumor growth and sensitize chemotherapy through antitumor immunity

With the advancing comprehension of immunology, an increasing number of immunotherapies are being explored and implemented in the field of cancer treatment. The cGAS-STING pathway, a crucial element of the innate immune response, has been identified as pivotal in cancer immunotherapy. We evaluated the antitumor effects of Schisandra chinensis lignan component Schisandrin C (SC) in 4T1 and MC38 tumor-bearing mice, and studied the enhancing effects of SC on the cGAS-STING pathway and antitumor immunity through RNA sequencing, qRT-PCR, and flow cytometry. Our findings revealed that SC significantly inhibited tumor growth in models of both breast and colon cancer. This suppression of tumor growth was attributed to the activation of type I IFN response and the augmented presence of T cells and NK cells within the tumor. Additionally, SC markedly promoted the cGAS-STING pathway activation induced by cisplatin. In comparison to cisplatin monotherapy, the combined treatment of SC and cisplatin exhibited a greater inhibitory effect on tumor growth. The amplified chemotherapeutic efficacy was associated with an enhanced type I IFN response and strengthened antitumor immunity. SC was shown to reduce tumor growth and increase chemotherapy sensitivity by enhancing the type I IFN response activation and boosting antitumor immunity, which enriched the research into the antitumor immunity of S. chinensis and laid a theoretical basis for its application in combating breast and colon cancer.

Polydatin attenuates diabetic renal inflammatory fibrosis via the inhibition of STING pathway

Diabetic nephropathy (DN) is a complication of diabetes and is mainly characterized by renal fibrosis, which could be attributed to chronic kidney inflammation. Stimulator of interferon genes (STING), a linker between immunity and metabolism, could ameliorate various metabolic and inflammatory diseases. However, the regulatory role of STING in DN remains largely unexplored. In this study, knockdown of STING decreased extracellular matrix (ECM), pro-inflammatory, and fibrotic factors in high glucose (HG)-induced glomerular mesangial cells (GMCs), whereas overexpression of STING triggered the inflammatory fibrosis process, suggesting that STING was a potential target for DN. Polydatin (PD) is a glucoside of resveratrol and has been reported to ameliorate DN by inhibiting inflammatory responses. Nevertheless, whether PD improved DN via STING remains unclear. Here, transcriptomic profiling implied that the STING/NF-κB pathway might be an important target for PD. We further found that PD decreased the protein expression of STING, and subsequently suppressed the activation of downstream targets including TBK1 phosphorylation and NF-κB nuclear translocation, and eventually inhibited the production of ECM, pro-inflammatory and fibrotic factors in HG-induced GMCs. Notably, results of molecular docking, molecular dynamic simulations, surface plasmon resonance, cellular thermal shift assay and Co-immunoprecipitation assay indicated that PD directly bound to STING and restored the declined proteasome-mediated degradation of STING induced by HG. In diabetic mice, PD also inhibited the STING pathway and improved the pathological changes of renal inflammatory fibrosis. Our study elucidated the regulatory role of STING in DN, and the novel mechanism of PD treating DN via inhibiting STING expression.

Mitophagy and cGAS-STING crosstalk in neuroinflammation

Mitophagy, essential for mitochondrial health, selectively degrades damaged mitochondria. It is intricately linked to the cGAS-STING pathway, which is crucial for innate immunity. This pathway responds to mitochondrial DNA and is associated with cellular stress response. Our review explores the molecular details and regulatory mechanisms of mitophagy and the cGAS-STING pathway. We critically evaluate the literature demonstrating how dysfunctional mitophagy leads to neuroinflammatory conditions, primarily through the accumulation of damaged mitochondria, which activates the cGAS-STING pathway. This activation prompts the production of pro-inflammatory cytokines, exacerbating neuroinflammation. This review emphasizes the interaction between mitophagy and the cGAS-STING pathways. Effective mitophagy may suppress the cGAS-STING pathway, offering protection against neuroinflammation. Conversely, impaired mitophagy may activate the cGAS-STING pathway, leading to chronic neuroinflammation. Additionally, we explored how this interaction influences neurodegenerative disorders, suggesting a common mechanism underlying these diseases. In conclusion, there is a need for additional targeted research to unravel the complexities of mitophagy-cGAS-STING interactions and their role in neurodegeneration. This review highlights potential therapies targeting these pathways, potentially leading to new treatments for neuroinflammatory and neurodegenerative conditions. This synthesis enhances our understanding of the cellular and molecular foundations of neuroinflammation and opens new therapeutic avenues for neurodegenerative disease research.

Basic immunologic study as a foundation for engineered therapeutic development

Bioengineering and drug delivery technologies play an important role in bridging the gap between basic scientific discovery and clinical application of therapeutics. To identify the optimal treatment, the most critical stage is to diagnose the problem. Often these two may occur simultaneously or in parallel, but in this review, we focus on bottom-up approaches in understanding basic immunologic phenomena to develop targeted therapeutics. This can be observed in several fields; here, we will focus on one of the original immunotherapy targets-cancer-and one of the more recent targets-regenerative medicine. By understanding how our immune system responds in processes such as malignancies, wound healing, and medical device implantation, we can isolate therapeutic targets for pharmacologic and bioengineered interventions.

Gut microbiota affects the activation of STING pathway and thus participates in the progression of colorectal cancer

BACKGROUND

More and more studies showed that gut microbiota was closely related to the development of colorectal cancer (CRC). However, the specific pathway of gut microbiota regulating CRC development is still unknown.

METHODS

We collected fecal samples from 14 CRC patients and 20 normal volunteers for 16 S sequencing analysis. At the same time, 14 CRC patients' tumors and their adjacent tissues were collected for the detection of STING pathway related protein level. Mice were injected with azoxymethane (AOM) to establish an animal model of CRC, and antibiotics were given at the same time to evaluate the influence of gut microbiota on STING pathway and whether it was involved in regulating the tumor development of CRC mice.

RESULTS

The sequencing results showed that compared with the normal group, the gut microbiota gut microbiota of CRC patients changed significantly at different species classification levels. At the level of genus, Akkermansia, Ligilactobacillus and Subdoligranulum increased the most in CRC patients, while Bacteroides and Dialister decreased sharply. The expression of STING-related protein was significantly down-regulated in CRC tumor tissues. Antibiotic treatment of CRC mice can promote the development of tumor and inhibit the activation of STING pathway.

CONCLUSION

Gut microbiota participates in CRC progress by mediating STING pathway activation.

Tumor cell-directed STING agonist antibody-drug conjugates induce type III interferons and anti-tumor innate immune responses

Activating interferon responses with STING agonists (STINGa) is a current cancer immunotherapy strategy, and therapeutic modalities that enable tumor-targeted delivery via systemic administration could be beneficial. Here we demonstrate that tumor cell-directed STING agonist antibody-drug-conjugates (STINGa ADCs) activate STING in tumor cells and myeloid cells and induce anti-tumor innate immune responses in in vitro, in vivo (in female mice), and ex vivo tumor models. We show that the tumor cell-directed STINGa ADCs are internalized into myeloid cells by Fcγ-receptor-I in a tumor antigen-dependent manner. Systemic administration of STINGa ADCs in mice leads to STING activation in tumors, with increased anti-tumor activity and reduced serum cytokine elevations compared to a free STING agonist. Furthermore, STINGa ADCs induce type III interferons, which contribute to the anti-tumor activity by upregulating type I interferon and other key chemokines/cytokines. These findings reveal an important role for type III interferons in the anti-tumor activity elicited by STING agonism and provide rationale for the clinical development of tumor cell-directed STINGa ADCs.

Amino Acid Metabolism-Regulated Nanomedicine for Enhanced Tumor Immunotherapy through Synergistic Regulation of Immune Microenvironment

The reprogramming of tumor metabolism presents a substantial challenge for effective immunotherapy, playing a crucial role in developing an immunosuppressive microenvironment. In particular, the degradation of the amino acid L-tryptophan (Trp) to kynurenine (Kyn) by indoleamine-pyrrole 2,3-dioxygenase 1 (IDO1) is one of the most clinically validated pathways for immune suppression. Thus, regulating the Trp/Kyn metabolism by IDO1 inhibition represents a promising strategy for enhancing immunotherapy. Herein, metabolism-regulated nanoparticles are prepared through metal coordination-driven assembly of an IDO1 inhibitor (NLG919) and a stimulator of interferon genes (STING) agonist (MSA-2) for enhanced immunotherapy. After intravenous administration, the assembled nanoparticles could efficiently accumulate in tumors, enhancing the bioavailability of NLG919 and down-regulating the metabolism of Trp to Kyn to remodel the immunosuppressive tumor microenvironment. Meanwhile, the released MSA-2 evoked potent STING pathway activation in tumors, triggering an effective immune response. The antitumor immunity induced by nanoparticles significantly inhibited the development of primary and metastatic tumors, as well as B16 melanoma. Overall, this study provided a novel paradigm for enhancing tumor immunotherapy through synergistic amino acid metabolism and STING pathway activation.

STING agonist, SMA-2, inhibits clear cell renal cell carcinoma through improving tumor microenvironment

Clear cell renal cell carcinoma (ccRCC) is the most prevalent and lethal subtype of kidney cancer, patients with ccRCC usually have very poor prognosis and short survival. Therefore, it is urgent to develop more effective therapeutics or medications to suppress ccRCC progression. Here, we demonstrated that STING agonist, MSA-2 significantly inhibits tumor progress and prolongs the survival of ccRCC mice by promoting cytokines secretion. Moreover, MSA-2 triggered the trafficking and infiltration of CD8+ T cells, supported by the generation of a chemokine milieu that promoted recruitment and modulation of the immunosuppressive TME in ccRCC. These findings suggest that MSA-2 potentially serves an effective and preferable adjuvant immunotherapy of ccRCC.

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.