Dual roles of TLR7 in the lung cancer microenvironment

Tumor microenvironment immunomodulation by nanoformulated TLR 7/8 agonist and PI3k delta inhibitor enhances therapeutic benefits of radiotherapy

Infiltration of immunosuppressive cells into the breast tumor microenvironment (TME) is associated with suppressed effector T cell (Teff) responses, accelerated tumor growth, and poor clinical outcomes. Previous studies from our group and others identified infiltration of immunosuppressive myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs) as critical contributors to immune dysfunction in the orthotopic claudin-low tumor model, limiting the efficacy of adoptive cellular therapy. However, approaches to target these cells in the TME are currently lacking. To overcome this barrier, polymeric micellular nanoparticles (PMNPs) were used for the co-delivery of small molecule drugs activating Toll-like receptors 7 and 8 (TLR7/8) and inhibiting PI3K delta (PI3Kδ). The immunomodulation of the TME by TLR7/8 agonist and PI3K inhibitor led to type 1 macrophage polarization, decreased MDSC accumulation and selectively decreased tissue-resident Tregs in the TME, while enhancing the T and B cell adaptive immune responses. PMNPs significantly enhanced the anti-tumor activity of local radiation therapy (RT) in mice bearing orthotopic claudin-low tumors compared to RT alone. Taken together, these data demonstrate that RT combined with a nanoformulated immunostimulant diminished the immunosuppressive TME resulting in tumor regression. These findings set the stage for clinical studies of this approach.

Toll-like Receptors: Key Players in Squamous Cell Carcinoma Progression

Background/Objectives Lung squamous cell carcinoma (SCC) is one of the major subtypes of lung cancer, characterized by diverse molecular pathways and variable clinical outcomes. This study focused on assessing the levels of TLR-2, TLR-3, TLR-4, TLR-7, TLR-8, and TLR-9 on peripheral blood lymphocytes in patients with newly diagnosed SCC compared to a group of healthy controls, in the context of disease development and patient survival, conducted over three years. The study aimed to investigate the differences in TLR expression between SCC patients and healthy people and to understand their role in the development of the disease and patient survival over three years. Methods: The study included the assessment of TLR-2, TLR-3, TLR-4, TLR-7, TLR-8, and TLR-9 levels on peripheral blood lymphocytes in patients with newly diagnosed SCC and in the control group. The expression of TLRs was measured using flow cytometry, and the soluble forms of the tested TLRs were measured using enzyme-linked immunosorbent assays. All the analyses were conducted over a three-year period from the time patients were recruited to the study. The obtained test results were statistically analyzed. Results: Results showed statistically significant differences in TLR expression between the groups, with higher TLR levels correlating with an advanced stage of disease and poorer survival rates. This suggests that the deregulation of TLR levels may be involved in promoting tumor development and influencing its microenvironment. Conclusions: The research, conducted over three years, indicates the need for further research on the role of TLRs in SCC, including their potential use as therapeutic targets and biomarkers. This may help to increase the effectiveness of standard treatments and improve clinical outcomes in patients with SCC.

Tumor microenvironment immunomodulation by nanoformulated TLR 7/8 agonist and PI3k delta inhibitor enhances therapeutic benefits of radiotherapy

Infiltration of immunosuppressive cells into the breast tumor microenvironment (TME) is associated with suppressed effector T cell (Teff) responses, accelerated tumor growth, and poor clinical outcomes. Previous studies from our group and others identified infiltration of immunosuppressive myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs) as critical contributors to immune dysfunction in the orthotopic triple-negative breast cancer (TNBC) tumor model limiting the efficacy of adoptive cellular therapy. However, approaches to target these cells specifically in the TME are currently lacking. To overcome this barrier, polymeric micelles nanoparticles (PMNPs) were used for co-delivery of small molecule drugs activating Toll-like receptors 7 and 8 (TLR7/8) and inhibiting PI3K delta. The immunomodulation of the TME by TLR7/8 agonist and PI3K inhibitor altered macrophage polarization, reduced MDSC accumulation and selectively decreased tissue-resident Tregs in the TME, while enhancing the T and B cell adaptive immune response. PMNPs significantly enhanced the anti-tumor activity of local radiation therapy (RT) in mice bearing orthotopic TNBC tumors compared to RT alone. Taken together, these data demonstrate that RT combined with a nanoformulated immunostimulant restructured the TME and has promising potential for future translation combined with RT for patients with TNBC.

Immunotherapies inducing immunogenic cell death in cancer: insight of the innate immune system

Cancer immunotherapies include monoclonal antibodies, cytokines, oncolytic viruses, cellular therapies, and other biological and synthetic immunomodulators. These are traditionally studied for their effect on the immune system's role in eliminating cancer cells. However, some of these therapies have the unique ability to directly induce cytotoxicity in cancer cells by inducing immunogenic cell death (ICD). Unlike general immune stimulation, ICD triggers specific therapy-induced cell death pathways, based on the release of damage-associated molecular patterns (DAMPs) from dying tumour cells. These activate innate pattern recognition receptors (PRRs) and subsequent adaptive immune responses, offering the promise of sustained anticancer drug efficacy and durable antitumour immune memory. Exploring how onco-immunotherapies can trigger ICD, enhances our understanding of their mechanisms and potential for combination strategies. This review explores the complexities of these immunotherapeutic approaches that induce ICD, highlighting their implications for the innate immune system, addressing challenges in cancer treatment, and emphasising the pivotal role of ICD in contemporary cancer research.

Cuproptosis and Immune-Related Gene Signature Predicts Immunotherapy Response and Prognosis in Lung Adenocarcinoma

Cuproptosis and associated immune-related genes (IRG) have been implicated in tumorigenesis and tumor progression. However, their effects on lung adenocarcinoma (LUAD) have not been elucidated. Therefore, we investigated the impact of cuproptosis-associated IRGs on the immunotherapy response and prognosis of LUAD using a bioinformatical approach and in vitro experiments analyzing clinical samples. Using the cuproptosis-associated IRG signature, we classified LUAD into two subtypes, cluster 1 and cluster 2, and identified three key cuproptosis-associated IRGs, NRAS, TRAV38-2DV8, and SORT1. These three genes were employed to establish a risk model and nomogram, and to classify the LUAD cohort into low- and high-risk subgroups. Biofunctional annotation revealed that cluster 2, remarkably downregulating epigenetic, stemness, and proliferation pathways activity, had a higher overall survival (OS) and immunoinfiltration abundance compared to cluster 1. Real-time quantitative PCR (RT-qPCR) validated the differential expression of these three genes in both subgroups. scRNA-seq demonstrated elevated expression of NRAS and SORT1 in macrophages. Immunity and oncogenic and stromal activation pathways were dramatically enriched in the low-risk subgroup, and patients in this subgroup responded better to immunotherapy. Our data suggest that the cuproptosis-associated IRG signature can be used to effectively predict the immunotherapy response and prognosis in LUAD. Our work provides enlightenment for immunotherapy response assessment, prognosis prediction, and the development of potential prognostic biomarkers for LUAD patients.

The future of cancer immunotherapy: DNA vaccines leading the way

Immuno-oncology has revolutionized cancer treatment and has opened up new opportunities for developing vaccination methods. DNA-based cancer vaccines have emerged as a promising approach to activating the bodily immune system against cancer. Plasmid DNA immunizations have shown a favorable safety profile and there occurs induction of generalized as well as tailored immune responses in preclinical and early-phase clinical experiments. However, these vaccines have notable limitations in immunogenicity and heterogeneity and these require refinements. DNA vaccine technology has been focusing on improving vaccine efficacy and delivery, with parallel developments in nanoparticle-based delivery systems and gene-editing technologies such as CRISPR/Cas9. This approach has showcased great promise in enhancing and tailoring the immune response to vaccination. Strategies to enhance the efficacy of DNA vaccines include the selection of appropriate antigens, optimizing insertion in a plasmid, and studying combinations of vaccines with conventional strategies and targeted therapies. Combination therapies have attenuated immunosuppressive activities in the tumor microenvironment and enhanced the capability of immune cells. This review provides an overview of the current framework of DNA vaccines in oncology and focuses on novel strategies, including established combination therapies and those still under development.The challenges that oncologists, scientists, and researchers need to overcome to establish DNA vaccines as an avant-garde approach to defeating cancer, are also emphasized. The clinical implications of the immunotherapeutic approaches and the need for predictive biomarkers have also been reviewed upon. We have also tried to extend the role of Neutrophil extracellular traps (NETs) to the DNA vaccines. The clinical implications of the immunotherapeutic approaches have also been reviewed upon. Ultimately, refining and optimizing DNA vaccines will enable harnessing the immune system's natural ability to recognize and eliminate cancer cells, leading the world towards a revolution in cancer cure.

A new immune signature for survival prediction and immune checkpoint molecules in non-small cell lung cancer

Background

Immune checkpoint blockade (ICB) therapy has brought remarkable clinical benefits to patients with advanced non-small cell lung carcinoma (NSCLC). However, the prognosis remains largely variable.

Methods

The profiles of immune-related genes for patients with NSCLC were extracted from TCGA database, ImmPort dataset, and IMGT/GENE-DB database. Coexpression modules were constructed using WGCNA and 4 modules were identified. The hub genes of the module with the highest correlations with tumor samples were identified. Then integrative bioinformatics analyses were performed to unveil the hub genes participating in tumor progression and cancer-associated immunology of NSCLC. Cox regression and Lasso regression analyses were conducted to screen prognostic signature and to develop a risk model.

Results

Functional analysis showed that immune-related hub genes were involved in the migration, activation, response, and cytokine-cytokine receptor interaction of immune cells. Most of the hub genes had a high frequency of gene amplifications. MASP1 and SEMA5A presented the highest mutation rate. The ratio of M2 macrophages and naïve B cells revealed a strong negative association while the ratio of CD8 T cells and activated CD4 memory T cells showed a strong positive association. Resting mast cells predicted superior overall survival. Interactions including protein-protein, lncRNA and transcription factor interactions were analyzed and 9 genes were selected by LASSO regression analysis to construct and verify a prognostic signature. Unsupervised hub genes clustering resulted in 2 distinct NSCLC subgroups. The TIDE score and the drug sensitivity of gemcitabine, cisplatin, docetaxel, erlotinib and paclitaxel were significantly different between the 2 immune-related hub gene subgroups.

Conclusions

These findings suggested that our immune-related genes can provide clinical guidance for the diagnosis and prognosis of different immunophenotypes and facilitate the management of immunotherapy in NSCLC.

Configuring Therapeutic Aspects of Immune Checkpoints in Lung Cancer

Immune checkpoints are unique components of the body's defense mechanism that safeguard the body from immune responses that are potent enough to harm healthy body cells. When proteins present on the surface of T cells recognize and bind to the proteins present on other tumor cells, immune checkpoints are triggered. These proteins are called immunological checkpoints. The T cells receive an on/off signal when the checkpoints interact with companion proteins. This might avert the host's immune system from eliminating cancer cells. The standard care plan for the treatment of non-small cell lung cancer (NSCLC) has been revolutionized with the use of drugs targeting immune checkpoints, in particular programmed cell death protein 1. These drugs are now extended for their potential to manage SCLC. However, it is acknowledged that these drugs have specific immune related adverse effects. Herein, we discuss the use of immune checkpoint inhibitors in patients with NSCLC and SCLC, their outcomes, and future perspectives.

Targeting toll-like receptor 7/8 for immunotherapy: recent advances and prospectives

Toll-like receptors (TLRs) are a large family of proteins that are expressed in immune cells and various tumor cells. TLR7/8 are located in the intracellular endosomes, participate in tumor immune surveillance and play different roles in tumor growth. Activation of TLRs 7 and 8 triggers induction of a Th1 type innate immune response in the highly sophisticated process of innate immunity signaling with the recent research advances involving the small molecule activation of TLR 7 and 8. The wide range of expression and clinical significance of TLR7/TLR8 in different kinds of cancers have been extensively explored. TLR7/TLR8 can be used as novel diagnostic biomarkers, progression and prognostic indicators, and immunotherapeutic targets for various tumors. Although the mechanism of action of TLR7/8 in cancer immunotherapy is still incomplete, TLRs on T cells are involved in the regulation of T cell function and serve as co-stimulatory molecules and activate T cell immunity. TLR agonists can activate T cell-mediated antitumor responses with both innate and adaptive immune responses to improve tumor therapy. Recently, novel drugs of TLR7 or TLR8 agonists with different scaffolds have been developed. These agonists lead to the induction of certain cytokines and chemokines that can be applied to the treatment of some diseases and can be used as good adjutants for vaccines. Furthermore, TLR7/8 agonists as potential therapeutics for tumor-targeted immunotherapy have been developed. In this review, we summarize the recent advances in the development of immunotherapy strategies targeting TLR7/8 in patients with various cancers and chronic hepatitis B.

Understanding the role of Toll-like receptors in lung cancer immunity and immunotherapy

Lung cancer is currently the leading cause of cancer-related deaths worldwide. Significant improvements in lung cancer therapeutics have relied on a better understanding of lung cancer immunity and the development of novel immunotherapies, as best exemplified by the introduction of PD-1/PD-L1-based therapies. However, this improvement is limited to lung cancer patients who respond to anti-PD-1 immunotherapy. Further improvements in immunotherapy may benefit from a better understanding of innate immune response mechanisms in the lung. Toll-like receptors (TLRs) are a key component of the innate immune response and mediate the early recognition of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). TLR signaling modulates the tumor microenvironment from "cold" to "hot" leading to immune sensitization of tumor cells to treatments and improved patient prognosis. In addition, TLR signaling activates the adaptive immune response to improve the response to cancer immunotherapy through the regulation of anti-tumor T cell activity. This review will highlight recent progress in our understanding of the role of TLRs in lung cancer immunity and immunotherapy.

Evaluation of a Radio-IMmunoStimulant (RIMS) in a Syngeneic Model of Murine Prostate Cancer and ImmunoPET Analysis of T-cell Distribution

An immunosuppressive tumor microenvironment and tumor heterogeneity have led to the resilience of metastatic castrate resistant prostate cancer (mCRPC) to current treatments. To address these challenges, we developed and evaluated a new drug paradigm, Radio-IMmunostimulant (RIMS), in a syngeneic model of murine prostate cancer. RIMS-1 was generated using a convergent synthesis employing solid phase peptide and solution chemistries. The prostate-specific membrane antigen (PSMA) inhibitory constant for ^natLu-RIMS-1 was determined, and radiolabeling with ¹⁷⁷Lu generated ¹⁷⁷Lu-RIMS-1. The TLR 7/8 agonist payload release from ^natLu-RIMS-1 was determined using a cathepsin B assay. The biodistribution of ¹⁷⁷Lu-RIMS-1 was evaluated in a bilateral xenograft model in NCru nude mice bearing PSMA(+) (PC3-PiP) and PSMA(-) (PC3-Flu) tumors at 2, 24, and 72 h. The therapeutic effect of ¹⁷⁷Lu-RIMS-1 was evaluated in C57BL/6J mice bearing RM1-PGLS (PSMA-positive, green fluorescent protein-positive, and luciferase-positive) tumors and compared to that of ¹⁷⁷Lu-PSMA-617 at the same total administered radioactivity of 57 MBq and molar activity of 5.18 MBq/nmol. ^natLu-RIMS-1 and vehicle were evaluated as the controls. Immuno-positron emission tomography (PET) using ⁸⁹Zr-DFO-anti-CD3 was used to visualize T-cell distribution during treatment. ¹⁷⁷Lu-RIMS-1 was quantitatively radiolabeled at >99% radiochemical purity and maintained a high affinity toward PSMA (K_i = 3.77 ± 0.5 nM). Cathepsin B efficiently released the entire immunostimulant payload in 17.6 h. ¹⁷⁷Lu-RIMS-1 displayed a sustained uptake in PSMA(+) tumor tissue up to 72 h (2.65 ± 1.03% ID/g) and was not statistically different (P = 0.1936) compared to ¹⁷⁷Lu-PSMA-617 (3.65 ± 0.59% ID/g). All animals treated with ¹⁷⁷Lu-RIMS-1 displayed tumor growth suppression and provided a median survival of 30 days (P = 0.0007) while ¹⁷⁷Lu-PSMA-617 provided a median survival of 15 days, which was not statistically significant (P = 0.3548) compared to the vehicle group (14 days). ImmunoPET analysis revealed 2-fold more tumor infiltrating T-cells in ¹⁷⁷Lu-RIMS-1-treated animals compared to ¹⁷⁷Lu-PSMA-617-treated animals; ¹⁷⁷Lu-RIMS-1 improves therapeutic outcomes in a syngeneic model of mouse prostate cancer and elicits greater T-cell infiltration to the tumor compared to ¹⁷⁷Lu-PSMA-617. These results support further investigation of the RIMS paradigm as the first example of a single molecular entity combining radiotherapy and immunostimulation.

The TLR7/8 agonist R848 optimizes host and tumor immunity to improve therapeutic efficacy in murine lung cancer

Treatment with the Toll‑like receptor 7 (TLR7) agonist, resiquimod (R848), is effective in various types of cancer, such as breast, pancreatic and colorectal cancer. The reported antitumor effect of R848 in lung cancer is considered to be achieved by targeting macrophages. In the present study, it was demonstrated that TLR7 expression on various immune cell types initially rises, then declines in the late stage of lung cancer. Intraperitoneal injection of R848 resulted in a reduction in tumor burden and prolonged survival in both subcutaneous and metastatic lung cancer models in C57BL/6 mice. Initial treatment with R848 at an early stage was found to be the optimal choice. Systemic injection of R848 promoted the activation of innate and adaptive immune responses. Systemic administration of R848 upregulated TLR7 expression in dendritic cells (DCs) and enhanced the activation of DCs and natural killer (NK) cells. Moreover, this treatment also resulted in increased production of T helper cell‑associated cytokines in serum, including IFN‑γ, TNF‑α and IL‑2. In addition, continuous treatment with R848 increased the proportion of DCs, NK and CD8+ T cells, and reduced that of Foxp3+ regulatory T cells in the tumor microenvironment. These findings supported the use of R848 treatment for lung cancer via TLR7 targeting and provided insight into the underlying therapeutic mechanism.

Emerging role of RNA sensors in tumor microenvironment and immunotherapy

RNA sensors detect foreign and endogenous RNAs to protect the host by initiating innate and adaptive immune response. In tumor microenvironment (TME), activation of RNA sensors induces tumor-inhibitory cytotoxic T lymphocyte responses and inhibits the activity of immunosuppressive cells though stimulating type I IFN signaling pathway. These characteristics allow RNA sensors to be prospective targets in tumor immunotherapy. Therefore, a comprehensive understanding of the roles of RNA sensors in TME could provide new insight into the antitumor immunotherapy. Moreover, RNA sensors could be prominent triggering targets to synergize with immunotherapies. In this review, we highlight the diverse mechanisms of RNA sensors in cancer immunity and their emerging contributions in cancer immunotherapy, including monotherapy with RNA sensor agonists, as well as combination with chemotherapy, radiotherapy, immune checkpoint blockade or cancer vaccine.

Evolution of Toll-like receptor 7/8 agonist therapeutics and their delivery approaches: From antiviral formulations to vaccine adjuvants

Imidazoquinoline derivatives (IMDs) and related compounds function as synthetic agonists of Toll-like receptors 7 and 8 (TLR7/8) and one is FDA approved for topical antiviral and skin cancer treatments. Nevertheless, these innate immune system-activating drugs have potentially much broader therapeutic utility; they have been pursued as antitumor immunomodulatory agents and more recently as candidate vaccine adjuvants for cancer and infectious disease. The broad expression profiles of TLR7/8, poor pharmacokinetic properties of IMDs, and toxicities associated with systemic administration, however, are formidable barriers to successful clinical translation. Herein, we review IMD formulations that have advanced to the clinic and discuss issues related to biodistribution and toxicity that have hampered the further development of these compounds. Recent strategies aimed at enhancing safety and efficacy, particularly through the use of bioconjugates and nanoparticle formulations that alter pharmacokinetics, biodistribution, and cellular targeting, are described. Finally, key aspects of the biology of TLR7 signaling, such as TLR7 tolerance, that may need to be considered in the development of new IMD therapeutics are discussed.

A New Lectin from Auricularia auricula Inhibited the Proliferation of Lung Cancer Cells and Improved Pulmonary Flora

Lectins are widely distributed in the natural world and are usually involved in antitumor activities. Auricularia auricula (A. auricula) is a medicinal and edible homologous fungus. A. auricula contains many active ingredients, such as polysaccharides, melanin, flavonoids, adenosine, sterols, alkaloids, and terpenes. In this study, we expected to isolate and purify lectin from A. auricula, determine the glycoside bond type and sugar-specific protein of A. auricula lectin (AAL), and finally, determine its antitumor activities. We used ammonium sulfate fractionation, ion exchange chromatography, and affinity chromatography to separate and purify lectin from A. auricula. The result was a 25 kDa AAL with a relative molecular mass of 18913.22. Protein identification results suggested that this lectin contained four peptide chains by comparing with the UniProt database. The FT-IR and β-elimination reaction demonstrated that the connection between the oligosaccharide and polypeptide of AAL was an N-glucoside bond. Analyses of its physical and chemical properties showed that AAL was a temperature-sensitive and acidic/alkaline-dependent glycoprotein. Additionally, the anticancer experiment manifested that AAL inhibited the proliferation of A549, and the IC50 value was 28.19 ± 1.92 μg/mL. RNA sequencing dataset analyses detected that AAL may regulate the expression of JUN, TLR4, and MYD88 to suppress tumor proliferation. Through the pulmonary flora analysis, the bacterial structure of each phylum in the lectin treatment group was more reasonable, and the colonization ability of the normal microflora was improved, indicating that lectin treatment could significantly improve the bacterial diversity characteristics.

WGCNA identification of TLR7 as a novel diagnostic biomarker, progression and prognostic indicator, and immunotherapeutic target for stomach adenocarcinoma

Stomach adenocarcinoma (STAD) is a malignant tumor with high histological heterogeneity. However, the potential mechanism of STAD tumorigenesis remains to be elucidated. The purpose of our research was to identify candidate genes associated with the diagnosis, progression, prognosis, and immunotherapeutic targets of STAD. Based on tumor samples from the GSE28541 dataset, weighted gene co-expression network analysis revealed 16 modules related to STAD stage and grade. The salmon module emerged as the most relevant module (cor = 0.34), and functional enrichment analysis showed that the genes in the salmon were primarily related to major histocompatibility complex, immune response, and cell differentiation. Toll-like receptor 7 (TLR7) was recognized as the real hub gene in the salmon module. Compared to normal stomach tissues, the transcriptional and translational levels of TLR7 were significantly elevated in STAD. Receiver operating characteristic curves verified that TLR7 displayed remarkable sensitivity and specificity for the diagnosis of STAD. The functions of TLR7 were primarily enriched in the regulation of Toll-like receptor signaling pathway, pattern recognition receptor signaling pathway, and innate immune response. Overexpression of TLR7 tended to indicate more advanced STAD, higher degree of STAD, and poorer prognosis of STAD. In addition, TLR7 expression was positively correlated with immune cell infiltration and immune checkpoint expression. Somatic copy number alteration of TLR7 was also significantly related to immune cell infiltration. In conclusion, this study revealed the crucial role of TLR7 in STAD and provided new perspectives for the selection of biomarkers, progression and prognosis indicators, and immunotherapeutic targets for STAD.

Dual roles of myeloid-derived suppressor cells induced by Toll-like receptor signaling in cancer

Myeloid-derived suppressor cells (MDSCs) are one of the major components of the tumor microenvironment (TME), and are the main mediators of tumor-induced immunosuppression. Recent studies have reported that the survival, differentiation and immunosuppressive activity of MDSCs are affected by the Toll-like receptor (TLR) signaling pathway. However, the regulatory effect of TLR signaling on MDSCs remains controversial. TLR-induced MDSC can acquire different immunosuppressive activities to influence the immune response that can be either beneficial or detrimental to cancer immunotherapy. The present review summarizes the effects of TLR signals on the number, phenotype and inhibitory activity of MDSCs, and their role in cancer immunotherapy, which cannot be ignored if effective cancer immunotherapies are to be developed for the immunosuppression of the TME.

Combinational immunotherapy based on immune checkpoints inhibitors in small cell lung cancer: is this the beginning to reverse the refractory situation?

Small cell lung cancer (SCLC), a particular neuroendocrine tumor, occupies 13% of lung cancers, with the highest mortality among cancers. Immune checkpoints inhibitors (ICIs) based on programmed cell death protein-1 (PD-1)/programmed cell death one ligand (PD-L1) inhibitors and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors have been one of the most favorable therapies in SCLC. Simultaneously, not all the patients respond to ICIs due to the lack of biomarkers to predict the immunotherapeutic effect. Multiple combinational approaches are under exploration, including the integrated or successive assessment of additional immunotherapeutic agents, chemotherapy, radiotherapy, and targeted therapy with ICIs. The current review offers a general view of the rationale for clinical studies exploring the experimental result of combinational immunotherapy based on ICIs, with both available results and ongoing trials. Moreover, the development of more predictive biomarkers, specific clinical trial designs, enhancement of the efficacy, and decreasing the financial toxicity will become the trend of future research and clinical applications of ICIs. Understanding the evolving immuno-oncology is increasingly relevant and crucial to solve those problems and define therapeutic strategies and potential target populations of combinational immunotherapy. Ultimately, emerging combinational immunotherapy will transform SCLC into a chronic disease to help patients survive from tumors.

Novel and Selective TLR7 Antagonists among the Imidazo[1,2-a]pyrazines, Imidazo[1,5-a]quinoxalines, and Pyrazolo[1,5-a]quinoxalines Series

The Toll-like receptors (TLRs) 7 and 8 play an important role in the immune system activation, and their agonists may therefore serve as promising candidate vaccine adjuvants. However, the chronic immune activation by excessive TLR stimulation is a hallmark of several clinically important infectious and autoimmune diseases, which warrants the search for TLR antagonists. In this study, we have synthesized and characterized a variety of compounds belonging to three heterocyclic chemical series: imidazo[1,2-a]pyrazine, imidazo[1,5-a]quinoxaline, and pyrazolo[1,5-a]quinoxaline. These compounds have been tested for their TLR7 or TLR8 agonistic and antagonistic activities. Several of them are shown to be selective TLR7 antagonists without any TLR7 or TLR8 agonistic activity. The selectivity was confirmed by a comparative ligand-docking study in TLR7 antagonist pocket. Two compounds of the pyrazolo[1,5-a]quinoxaline series (10a and 10b) are potent selective TLR7 antagonists and may be considered as promising starting points for the development of new therapeutic agents.

Genetic variant of IRAK2 in the toll-like receptor signaling pathway and survival of non-small cell lung cancer

The toll-like receptor (TLR) signaling pathway plays an important role in the innate immune responses and antigen-specific acquired immunity. Aberrant activation of the TLR pathway has a significant impact on carcinogenesis or tumor progression. Therefore, we hypothesize that genetic variants in the TLR signaling pathway genes are associated with overall survival (OS) of patients with non-small cell lung cancer (NSCLC). To test this hypothesis, we first performed Cox proportional hazards regression analysis to evaluate associations between genetic variants of 165 TLR signaling pathway genes and NSCLC OS using the genome-wide association study (GWAS) dataset from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO). The results were further validated by the Harvard Lung Cancer Susceptibility GWAS dataset. Specifically, we identified IRAK2 rs779901 C > T as a predictor of NSCLC OS, with a variant-allele (T) attributed hazards ratio (HR) of 0.78 [95% confidence interval (CI) = 0.67-0.91, P = 0.001] in the PLCO dataset, 0.84 (0.72-0.98, 0.031) in the Harvard dataset, and 0.81 (0.73-0.90, 1.08x10-4 ) in the meta-analysis of these two GWAS datasets. In addition, the T allele was significantly associated with an increased mRNA expression level of IRAK2. Our findings suggest that IRAK2 rs779901 C > T may be a promising prognostic biomarker for NSCLC OS.

Toll like receptor 7 expressed by malignant cells promotes tumor progression and metastasis through the recruitment of myeloid derived suppressor cells

In non-small cell lung carcinoma (NSCLC), stimulation of toll-like receptor 7 (TLR7), a receptor for single stranded RNA, is linked to tumor progression and resistance to anticancer chemotherapy. However, the mechanism of this effect has been elusive. Here, using a murine model of lung adenocarcinoma, we demonstrate a key role for TLR7 expressed by malignant (rather than by stromal and immune) cells, in the recruitment of myeloid derived suppressor cells (MDSCs), induced after TLR7 stimulation, resulting in accelerated tumor growth and metastasis. In adenocarcinoma patients, high TLR7 expression on malignant cells was associated with poor clinical outcome, as well as with a gene expression signature linked to aggressiveness and metastastic dissemination with high abundance of mRNA encoding intercellular adhesion molecule 1 (ICAM-1), cytokeratins 7 and 19 (KRT-7 and 19), syndecan 4 (SDC4), and p53. In addition, lung tumors expressing high levels of TLR7 have a phenotype of epithelial mesenchymal transition with high expression of vimentin and low abundance of E-cadherin. These data reveal a crucial role for cancer cell-intrinsic TLR7 expression in lung adenocarcinoma progression.

Induction of oligoclonal CD8 T cell responses against pulmonary metastatic cancer by a phospholipid-conjugated TLR7 agonist

Recent advances in cancer immunotherapy have improved patient survival. However, only a minority of patients with pulmonary metastatic disease respond to treatment with checkpoint inhibitors. As an alternate approach, we have tested the ability of systemically administered 1V270, a toll-like receptor 7 (TLR7) agonist conjugated to a phospholipid, to inhibit lung metastases in two variant murine 4T1 breast cancer models, as well as in B16 melanoma, and Lewis lung carcinoma models. In the 4T1 breast cancer models, 1V270 therapy inhibited lung metastases if given up to a week after primary tumor initiation. The treatment protocol was facilitated by the minimal toxic effects exerted by the phospholipid TLR7 agonist compared with the unconjugated agonist. 1V270 exhibited a wide therapeutic window and minimal off-target receptor binding. The 1V270 therapy inhibited colonization by tumor cells in the lungs in an NK cell dependent manner. Additional experiments revealed that single administration of 1V270 led to tumor-specific CD8⁺ cell-dependent adaptive immune responses that suppressed late-stage metastatic tumor growth in the lungs. T cell receptor (TCR) repertoire analyses showed that 1V270 therapy induced oligoclonal T cells in the lungs and mediastinal lymph nodes. Different animals displayed commonly shared TCR clones following 1V270 therapy. Intranasal administration of 1V270 also suppressed lung metastasis and induced tumor-specific adaptive immune responses. These results indicate that systemic 1V270 therapy can induce tumor-specific cytotoxic T cell responses to pulmonary metastatic cancers and that TCR repertoire analyses can be used to monitor, and to predict, the response to therapy.

Pellino-1 confers chemoresistance in lung cancer cells by upregulating cIAP2 through Lys63-mediated polyubiquitination

Pellino-1 is an E3 ubiquitin ligase that mediates immune receptor signaling pathways. The role of Pellino-1 in oncogenesis of lung cancer was investigated in this study. Pellino-1 expression was increased in human lung cancer cell lines compared with non-neoplastic lung cell lines. Pellino-1 overexpression in human lung cancer cells, A549 and H1299 cells, increased the survival and colony forming ability. Pellino-1 overexpression in these cells also conferred resistance to cisplatin- or paclitaxel-induced apoptosis. In contrast, depletion of Pellino-1 decreased the survival of A549 and H1299 cells and sensitized these cells to cisplatin- and paclitaxel-induced apoptosis. Pellino-1 overexpression in A549 and H1299 cells upregulated the expression of inhibitor of apoptosis (IAP) proteins, including cIAP1 and cIAP2, while Pellino-1 depletion downregulated these molecules. Notably, Pellino-1 directly interacted with cIAP2 and stabilized cIAP2 through lysine63-mediated polyubiquitination via its E3 ligase activity. Pellino-1-mediated chemoresistance in lung cancer cells was dependent on the induction of cIAP2. Moreover, a strong positive correlation between Pellino-1 and the cIAP2 expression was observed in human lung adenocarcinoma tissues. Taken together, these results demonstrate that Pellino-1 contributes to lung oncogenesis through the overexpression of cIAP2 and promotion of cell survival and chemoresistance. Pellino-1 might be a novel oncogene and potential therapeutic target in lung cancer.

Toll-like receptor expression in human non-small cell lung carcinoma: potential prognostic indicators of disease

Introduction

Lung cancer remains the highest cause of cancer mortality worldwide. Toll-like receptors (TLR) are innate immune receptors that have both pro- and anti-tumorigenic properties. Based on findings from epidemiological studies and in rodents, we hypothesized that elevated TLR expression would be a positive prognostic indicator of disease in non-small cell lung carcinoma patients.

Results

Higher mRNA expression of TLR1-3 and 5-8 were significantly associated with increased overall survival (OS) when analyzed individually or as a group in both non-small cell lung carcinoma (NSCLC) patients and in the adenocarcinoma (ADC) subtype. Significant co-expression of many TLR combinations in ADC patients were also observed via RNA sequencing. Immunostaining demonstrated TLR4 and 8 significantly correlated in tumor tissue, similar to RNA.

Methods

We used kmplot.com to perform a meta-analysis on mRNA expression of TLR1-10 to determine any significant associations with OS in NSCLC and the ADC subtype. cBioportal was also used simultaneously to assess co-expression in TLR1-10 in ADC patients via RNA sequencing and to identify any molecular alterations. Lastly, immunostaining for a subset of TLRs was conducted on ADC patients.

Conclusions

Expression of innate immune receptors TLR1-10 is associated with improved survival outcomes in NSCLC. Thus, further evaluation of their predictive capacity and therapeutic utility is warranted.

Immunomodulatory effects of myeloid-derived suppressor cells in diseases: Role in cancer and infections

Myeloid-derived suppressor cells (MDSCs) are heterogeneous cells capable of abrogating T and B cells responses and have been identified in numerous cancers. As with other regulatory cell populations, they aim to maintain balance between host-defence-associated inflammation and ensuing tissue pathology. MDSC accumulation and/or activation involve several growth factors and cytokines including Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) and Interleukin (IL)-6 and suppression has been linked to receptors such as IL-4Rα. Other immune pathways, such as Toll-like receptors (TLRs) have also been shown to interfere in MDSC activity adding to the complexity in clarifying their pathways. Monocytic- (Mo-MDSCs) and polymorphonuclear- (PMN-MDSCs) cells are two subsets of MDSCs that have been well characterized and have been shown to function through different mechanisms although both appear to require nitric oxide. In human and murine model settings, MDSCs have been shown to have inhibitory effects on T cell responses during bacterial, parasitic and viral pathologies and an increase of MDSC numbers has been associated with pathological conditions. Interestingly, the environment impacts on MDSC activity and regulatory T cells (Tregs), mast cells and a few cells that may help MDSC in order to regulate immune responses. Since the majority of pioneering data on MDSCs has stemmed from research on malignancies, this review will summarize MDSC biology and function in cancer and highlight current knowledge about these cells during infectious pathologies as well.

MUC1-C integrates PD-L1 induction with repression of immune effectors in non-small-cell lung cancer

Immunotherapeutic approaches, particularly PD-1/PD-L1 blockade, have improved the treatment of non-small cell lung cancer (NSCLC), supporting the premise that evasion of immune destruction is of importance for NSCLC progression. However, the signals responsible for upregulation of PD-L1 in NSCLC cells and whether they are integrated with the regulation of other immune-related genes are not known. Mucin 1 (MUC1) is aberrantly overexpressed in NSCLC, activates the NF-κB p65→ZEB1 pathway and confers a poor prognosis. The present studies demonstrate that MUC1-C activates PD-L1 expression in NSCLC cells. We show that MUC1-C increases NF-κB p65 occupancy on the CD274/PD-L1 promoter and thereby drives CD274 transcription. Moreover, we demonstrate that MUC1-C-induced activation of NF-κB→ZEB1 signaling represses the TLR9, IFNG, MCP-1 and GM-CSF genes, and that this signature is associated with decreases in overall survival. In concert with these results, targeting MUC1-C in NSCLC tumors suppresses PD-L1 and induces these effectors of innate and adaptive immunity. These findings support a previously unrecognized central role for MUC1-C in integrating PD-L1 activation with suppression of immune effectors and poor clinical outcome.

Toll-like receptor stimulation in cancer: A pro- and anti-tumor double-edged sword

Toll-like receptors (TLRs) are a family of transmembrane receptors that recognize various pathogen- and damage-associated molecular pattern molecules playing an important role in inflammation by activating NF-кB. TLRs, mainly expressed by innate immune cells, are involved in inducing and regulating adaptive immune responses. However, the expression of TLRs has also been observed in many tumors, and their stimulation results in tumor progression or regression, depending on the TLR and tumor type. Here we review the role of TLRs in conferring anti- or pro-tumoral effects. The anti-tumoral effects can result from direct induction of tumor cell death and/or activation of efficient anti-tumoral immune responses, and the pro-tumoral effects may be due to inducing tumor cell survival and proliferation or by acting on suppressive or inflammatory immune cells in the tumor microenvironment.