The TLR7 agonist induces tumor regression both by promoting CD4⁺T cells proliferation and by reversing T regulatory cell-mediated suppression via dendritic cells

Design, synthesis and biological evaluation of quinazoline and pyrrolo[3,2-d]pyrimidine derivatives as TLR7 agonists for antiviral agents

Pattern recognition receptors (PRRs) play a critical role in the innate immune response, and toll-like receptor 7 (TLR7) is an important member of PRRs. Although several TLR7 agonists are available, most of them are being tested clinically, with only one available on the market. Thus, it is imperative to develop new TLR7 agonists. In this study, we designed and synthesized three kinds of quinazoline derivatives and five kinds of pyrrolo[3,2-d]pyrimidine derivatives targeting TLR7. The antiviral efficacy of these compounds was evaluated in vitro and in vivo. Our findings indicated that four kinds of compounds showed exceptional antiviral activity. Furthermore, molecular docking studies confirmed that compound 11 successfully positioned itself in the pocket of the TLR7 guanosine loading site with a binding energy of -4.45 kcal mol-1. These results suggested that these compounds might be potential antiviral agents.

Synthetic Stimulator of Interferon Genes (STING) Agonists Induce a Cytokine-Mediated Anti-Hepatitis B Virus Response in Nonparenchymal Liver Cells

Chronic hepatitis B (CHB) remains a major public health problem worldwide, with limited treatment options, but inducing an antiviral response by innate immunity activation may provide a therapeutic alternative. We assessed the cytokine-mediated anti-hepatitis B virus (HBV) potential for stimulating the cyclic GMP-AMP synthase-stimulator of interferon genes (STING) pathway using STING agonists in primary human hepatocytes (PHH) and nonparenchymal liver cells (NPCs). The natural STING agonist, 2',3'-cyclic GMP-AMP, the synthetic analogue 3',3'-c-di(2'F,2'dAMP), and its bis(pivaloyloxymethyl) prodrug had strong indirect cytokine-mediated anti-HBV effects in PHH regardless of HBV genotype. Furthermore, STING agonists induced anti-HBV cytokine secretion in vitro, in both human and mouse NPCs, and triggered hepatic T cell activation. Cytokine secretion and lymphocyte activation were equally stimulated in NPCs isolated from control and HBV-persistent mice. Therefore, STING agonists modulate immune activation regardless of HBV persistence, paving the way toward a CHB therapy.

Combination Treatment of Topical Imiquimod Plus Anti-PD-1 Antibody Exerts Significantly Potent Antitumor Effect

The exact mechanisms of the imiquimod (IMQ)-induced antitumor effect have not been fully understood. Although both topical IMQ treatment and anti-PD-1 antibody may be used for primary skin lesions or skin metastases of various cancers, the efficacy of each monotherapy for these lesions is insufficient. Using a murine tumor model and human samples, we aimed to elucidate the detailed mechanisms of the IMQ-induced antitumor effect and analyzed the antitumor effect of combination therapy of topical IMQ plus anti-PD-1 antibody. Topical IMQ significantly suppressed the tumor growth of MC38 in wildtype mice. IMQ upregulated interferon γ (IFN-γ) expression in CD8⁺ T cells in both the lymph nodes and the tumor, and the antitumor effect was abolished in both Rag1-deficient mice and IFN-γ-deficient mice, indicating that IFN-γ produced by CD8⁺ T cells play a crucial role in the IMQ-induced antitumor effect. IMQ also upregulated PD-1 expression in T cells as well as PD-L1/PD-L2 expression in myeloid cells, suggesting that IMQ induces not only T-cell activation but also T-cell exhaustion by enhanced PD-1 inhibitory signaling. Combination therapy of topical IMQ plus anti-PD-1 antibody exerted a significantly potent antitumor effect when compared with each single therapy, indicating that the combination therapy is a promising therapy for the skin lesions of various cancers.

Gene-engineered exosomes-thermosensitive liposomes hybrid nanovesicles by the blockade of CD47 signal for combined photothermal therapy and cancer immunotherapy

CD47, overexpressed on kinds of tumor cells, activates a "don't eat me" signal through binding to signal regulatory protein α (SIRPα), leading to immune escape from the mononuclear phagocyte system (MPS). It is also a huge challenge to deliver therapeutic drugs to the tumor sites due to the short retention time in blood, poor targeting of tumor cells and accelerated clearance by MPS. Herein, we designed a hybrid therapeutic nanovesicles, named as hGLV, by fusing gene-engineered exosomes with drug-loaded thermosensitive liposomes. We demonstrated that the CD47-overexpressed hGLV exhibited the long blood circulation and improved the macrophages-mediated the phagocytosis of tumor cells by blocking CD47 signal. Moreover, the resulted hGLV could remarkably target the homologous tumor in mice, achieving the preferential accumulation at the tumor sites. Importantly, hGLV loading the photothermal agent could achieve the excellent photothermal therapy (PTT) under laser irradiation after the intravenous injection, completely eliminating the tumors, leading to immunogenic cell death and generating substantial tumor-associated antigens, which could promote the maturation of immature dendritic cells with the help of the co-encapsulated immune adjuvant to trigger strong immune responses. Generally, the hybrid nanovesicles based on CD47 immune check point blockade can be a promising platform for the drug delivery in cancer treatment.

A TLR7 agonist activates bovine Th1 response and exerts antiviral activity against bovine leukemia virus

Bovine leukemia virus (BLV) infection is a bovine chronic infection caused by BLV, a member of the genus Deltaretrovirus. In this study, we examined the immunomodulatory effects of GS-9620, a toll-like receptor (TLR) 7 agonist, in cattle (Bos taurus) and its therapeutic potential for treating BLV infection. GS-9620 induced cytokine production in peripheral blood mononuclear cells (PBMCs) as well as CD80 expression in CD11c⁺ cells and increased CD69 and interferon (IFN)-γ expressions in T cells. Removing CD11c⁺ cells from PBMCs decreased CD69 expression in T cells in the presence of GS-9620. These results suggest that TLR7 agonism promotes T-cell activation via CD11c⁺ cells. Analyses using PBMCs from BLV-infected cattle revealed that TLR7 expression in CD11c⁺ cells was upregulated during late-stage BLV infection. Furthermore, GS-9620 increased IFN-γ and TNF-α production and inhibited syncytium formation in vitro, suggesting that GS-9620 may be used to treat BLV infection.

Dendritic cell biology and its role in tumor immunotherapy

As crucial antigen presenting cells, dendritic cells (DCs) play a vital role in tumor immunotherapy. Taking into account the many recent advances in DC biology, we discuss how DCs (1) recognize pathogenic antigens with pattern recognition receptors through specific phagocytosis and through non-specific micropinocytosis, (2) process antigens into small peptides with proper sizes and sequences, and (3) present MHC-peptides to CD4⁺ and CD8⁺ T cells to initiate immune responses against invading microbes and aberrant host cells. During anti-tumor immune responses, DC-derived exosomes were discovered to participate in antigen presentation. T cell microvillar dynamics and TCR conformational changes were demonstrated upon DC antigen presentation. Caspase-11-driven hyperactive DCs were recently reported to convert effectors into memory T cells. DCs were also reported to crosstalk with NK cells. Additionally, DCs are the most important sentinel cells for immune surveillance in the tumor microenvironment. Alongside DC biology, we review the latest developments for DC-based tumor immunotherapy in preclinical studies and clinical trials. Personalized DC vaccine-induced T cell immunity, which targets tumor-specific antigens, has been demonstrated to be a promising form of tumor immunotherapy in patients with melanoma. Importantly, allogeneic-IgG-loaded and HLA-restricted neoantigen DC vaccines were discovered to have robust anti-tumor effects in mice. Our comprehensive review of DC biology and its role in tumor immunotherapy aids in the understanding of DCs as the mentors of T cells and as novel tumor immunotherapy cells with immense potential.

Dendritic cell biology and its role in tumor immunotherapy

As crucial antigen presenting cells, dendritic cells (DCs) play a vital role in tumor immunotherapy. Taking into account the many recent advances in DC biology, we discuss how DCs (1) recognize pathogenic antigens with pattern recognition receptors through specific phagocytosis and through non-specific micropinocytosis, (2) process antigens into small peptides with proper sizes and sequences, and (3) present MHC-peptides to CD4⁺ and CD8⁺ T cells to initiate immune responses against invading microbes and aberrant host cells. During anti-tumor immune responses, DC-derived exosomes were discovered to participate in antigen presentation. T cell microvillar dynamics and TCR conformational changes were demonstrated upon DC antigen presentation. Caspase-11-driven hyperactive DCs were recently reported to convert effectors into memory T cells. DCs were also reported to crosstalk with NK cells. Additionally, DCs are the most important sentinel cells for immune surveillance in the tumor microenvironment. Alongside DC biology, we review the latest developments for DC-based tumor immunotherapy in preclinical studies and clinical trials. Personalized DC vaccine-induced T cell immunity, which targets tumor-specific antigens, has been demonstrated to be a promising form of tumor immunotherapy in patients with melanoma. Importantly, allogeneic-IgG-loaded and HLA-restricted neoantigen DC vaccines were discovered to have robust anti-tumor effects in mice. Our comprehensive review of DC biology and its role in tumor immunotherapy aids in the understanding of DCs as the mentors of T cells and as novel tumor immunotherapy cells with immense potential.

In Ovo Delivered Toll-Like Receptor 7 Ligand, Resiquimod Enhances Host Responses against Infectious Bronchitis Corona Virus (IBV) Infection

Toll-like receptor (TLR) 7 ligand, resiquimod, has been studied as an adjuvant and antiviral agent against several pathogens in chicken. Yet, the effectiveness of resiquimod against infectious bronchitis virus (IBV) infection has not been evaluated. In this study, we investigated the effectiveness of resiquimod delivered pre-hatch (in ovo) against IBV infection post-hatch identifying key mechanisms involved in resiquimod driven immune activation. First, we found an upregulation of interleukin (IL)-1β and interferon (IFN)-γ mRNA levels and considerable expansions of macrophage and cluster of differentiation (CD) 8α+ T cell populations in lungs of chicken as early as day one post-hatch, following pre-hatch delivery of resiquimod. Second, we observed that resiquimod was able to act as an adjuvant when resiquimod was delivered pre-hatch along with an inactivated IBV vaccine. Finally, when the resiquimod pretreated one-day-old chickens were infected with IBV, reduction in viral shedding via oral and fecal routes was observed at 3 days post- infection. Overall, this study shows that the pre-hatch delivered resiquimod increases cell-mediated immune responses in lungs with an advantage of reduction in IBV shedding.

Differential effects of peptidoglycan on colorectal tumors and intestinal tissue post-pelvic radiotherapy

Immediate medical intervention is required after pelvic tumor radiotherapy to protect the radiosensitive intestine and also to mitigate tumor growth. Toll-like receptors (TLRs) have been shown to promote tissue repair processes. Here, we analyzed the effect observed upon combining the TLR2 agonist, peptidoglycan (PGN), with radiation therapy on tumors as well as intestinal tissue, both in vitro and in vivo. In contrast to radiotherapy alone, PGN when combined with ionizing radiation (IR) elicited enhanced antitumor effects and also reduced the IR-induced intestinal damage. Mechanistic studies showed that PGN first induced an IL13 response in the irradiated intestine, but was decreased in tumor cell models screened by Th1/Th2 FlowCytomix assay and validated by the application of IL13 and anti-IL13 neutralizing antibodies. Next, PGN stimulated Akt3, but not Akt1/2, as was verified by AKT1/2/3 plasmid transfection assay and in AKT1/2/3 knockout mice in vivo. Akt3 expression was inhibited in 20 μg/mL PGN-treated tumor cells and in 1.5 mg/kg PGN-treated mouse tumor models. However, Akt3 was raised via IL13 in the irradiated intestine and human intestinal cell line after the same treatment. Finally, PGN activated mTOR via IL13/AKT3 in the intestine and restored intestinal structure and function. As an adjuvant to radiotherapy, PGN inhibited tumorigenesis by suppression of mTOR activity. To summarize, the IL13/AKT3/mTOR pathway was lessened in PGN-treated irradiated tumors but was raised in the normal intestine tissue. This distinct effect of PGN on normal and tumor tissues during pelvic radiotherapy suggests that PGN may be a promising adjuvant therapy to radiation.

Systemic administration of a TLR7 agonist attenuates regulatory T cells by dendritic cell modification and overcomes resistance to PD-L1 blockade therapy

Research on immune checkpoint blockade therapy has made great progress in cancer immunotherapy, but the number of patients who benefit from this therapy remains limited. In this study, we examined the effects of monotherapy with systemic low-dose resiquimod, a synthesized TLR7 agonist, and examined its combined effects with PD-L1 blockade in two PD-L1 blockade-resistant tumor models (SCCVII and Colon 26). Resiquimod monotherapy in SCCVII tumors, representing impaired CD8⁺ T cell function and accelerated regulatory T cells (Tregs) within the tumors, efficiently reduced tumor growth with more recruitment of CD8⁺ T cells and a reduction of Treg. The results of resiquimod monotherapy in Colon 26, representing impaired Treg recruitment, were inferior to that in SCCVII. Combined resiquimod treatment with PD-L1 blockade exerted clear additional effects, as it was associated with reduced tumor size, attenuation of Tregs, and an increased ratio of CD8⁺ T cells/Tregs in both tumors. Systemic administration of low-dose resiquimod induced a transient and rapid activation of plasmacytoid and conventional dendritic cells, resulting in enhanced priming of T cells in regional lymph nodes. Experiments with more limited doses of resiquimod that did not yield beneficial effects after single treatment, showed additional effects to PD-L1 blockade and comparable antitumor effects when the frequency of anti-PD-L1 therapy was decreased. Our results suggest that systemic administration of low-dose resiquimod is useful as a companion drug to PD-1/PD-L1 blockade therapy.

Nanoparticles: augmenting tumor antigen presentation for vaccine and immunotherapy treatments of cancer

The major goal of immunity is maintaining host survival. Toward this, immune cells recognize and eliminate targets that pose a danger. Primarily, these are external invaders (pathogens) and internal invaders (cancers). Their recognition relies on distinguishing foreign components (antigens) from self-antigens. Since cancer cells are the host's own cells that are harmfully altered, they are difficult to distinguish from normal self. Furthermore, the antigens least resembling the host are often sequestered in parts of the tumor least accessible to immune responses. Therefore, to sufficiently boost immunity, these tumor antigens must be exposed to the immune system. Toward this, nanoparticles provide an innovating means of tumor antigen presentation and are destined to become an integral part of cancer immunotherapy.

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.

A TLR7 agonist enhances the antitumor efficacy of obinutuzumab in murine lymphoma models via NK cells and CD4 T cells

Anti-CD20 monoclonal antibodies (mAb) such as rituximab have been proven to be highly effective at improving outcome in B-cell malignancies. However, many patients ultimately relapse and become refractory to treatment. The glycoengineered anti-CD20 mAb obinutuzumab was developed to induce enhanced antibody-dependent cellular cytotoxicity, antibody-dependent phagocytosis and direct cell death and was shown to lead to improved outcomes in a randomized study in B-CLL. We hypothesized that immune stimulation through Toll-like receptor 7 (TLR7) agonism in combination with obinutuzumab would further enhance lymphoma clearance and the generation of long-term antitumor immune responses. Here we demonstrate, in syngeneic human CD20 (hCD20)-expressing models of lymphoma, that systemic administration of a TLR7 agonist (R848) increases responses when administered in combination with obinutuzumab and protects against disease recurrence. Depletion studies demonstrate that primary antitumor activity is dependent on both NK cells and CD4+ T cells but not on CD8+ T cells. However, both CD4+ and CD8+ T cells appear necessary for the generation of protective immunological memory. Importantly, increased tumor-free survival post obinutuzumab and R848 combination therapy was seen in hCD20 transgenic mice, which express hCD20 on normal B cells. These findings provide a rationale for clinical testing of obinutuzumab in combination with systemically administered TLR7 agonists to further improve outcome.

Anti-tumor Activity of Toll-Like Receptor 7 Agonists

Toll-like receptors (TLRs) are a class of pattern recognition receptors that play a bridging role in innate immunity and adaptive immunity. The activated TLRs not only induce inflammatory responses, but also elicit the development of antigen specific immunity. TLR7, a member of TLR family, is an intracellular receptor expressed on the membrane of endosomes. TLR7 can be triggered not only by ssRNA during viral infections, but also by immune modifiers that share a similar structure to nucleosides. Its powerful immune stimulatory action can be potentially used in the anti-tumor therapy. This article reviewed the anti-tumor activity and mechanism of TLR7 agonists that are frequently applied in preclinical and clinical investigations, and mainly focused on small synthetic molecules, including imiquimod, resiquimod, gardiquimod, and 852A, etc.

Enhancement of adoptive T cell transfer with single low dose pretreatment of doxorubicin or paclitaxel in mice

Ex vivo expansion of CD8+ T-cells has been a hindrance for the success of adoptive T cell transfer in clinic. Currently, preconditioning with chemotherapy is used to modulate the patient immunity before ACT, however, the tumor microenvironment beneficial for transferring T cells may also be damaged. Here preconditioning with single low dose of doxorubicin or paclitaxel combined with fewer CD8+ T-cells was investigated to verify whether the same therapeutic efficacy of ACT could be achieved. An E.G7/OT1 animal model that involved adoptive transfer of OVA-specific CD8+ T-cells transduced with a granzyme B promoter-driven firefly luciferase and tomato fluorescent fusion reporter gene was used to evaluate this strategy. The result showed that CD8+ T-cells were activated and sustained longer in mice pretreated with one low-dose Dox or Tax. Enhanced therapeutic efficacy was found in Dox or Tax combined with 2x106 CD8+ T-cells and achieved the same level of tumor growth inhibition as that of 5x106 CD8+ T-cells group. Notably, reduced numbers of Tregs and myeloid derived suppressor cells were shown in combination groups. By contrast, the number of tumor-infiltrating cytotoxic T lymphocytes and IL-12 were increased. The NF-κB activity and immunosuppressive factors such as TGF-β, IDO, CCL2, VEGF, CCL22, COX-2 and IL-10 were suppressed. This study demonstrates that preconditioning with single low dose Dox or Tax and combined with two fifth of the original CD8+ T-cells could improve the tumor microenvironment via suppression of NF-κB and its related immunosuppressors, and activate more CD8+ T-cells which also stay longer.

Rabies virus lipopeptide conjugated to a TLR7 agonist improves the magnitude and quality of the Th1-biased humoral immune response in mice

In this study, we conjugated the rabies-derived lipopeptide CE536 to a TLR7 agonist, imiquimod, and evaluated its adjuvanticity. The synthetic construct (Lipo-I) targeted to TLR7, induced dendritic cell phenotypic maturation and production of both type I interferon and pro-inflammatory cytokines more efficiently than unconjugated TLR7 ligands or lipopeptide alone. The immunostimulatory effects of the conjugate were apparently the result of IκBα degradation and sustained p38 and JNK phosphorylation. The analysis of IgG isotypes and T cell differentiation showed that IgG2a dominant Th1-biased humoral and CD8(+) IFN-γ T cell responses were induced by Lipo-I. Lipo-I could facilitate the rabies vaccine to induce the production of an earlier and more vigorous rabies virus neutralizing antibody. In the post-exposure test, the Lipo-I adjuvanted vaccine provided a 73.3% survival rate, while the traditional vaccine bestowed only a 26.7% survival. Therefore, Lipo-I is a promising adjuvant for the development of more effective rabies vaccines.

In situ photoimmunotherapy for cutaneous granuloma caused by itraconazole-resistant Candida guilliermondii

Cutaneous granulomas caused by Candida guilliermondii are difficult to cure. In situ photoimmunotherapy (ISPI) is a novel method composed of local photothermal therapy and immunoadjuvant. In this study, ISPI was used the first time clinically for cutaneous granuloma caused by itraconazole-resistant C.guilliermondii. A 10-week cycle of ISPI was composed of (1) 5% imiquimod applied topically every other day and (2) irradiation of lesions with an 808-nm diode laser at Days 14, 28, 42, and 56. Here we report our first case. A patient was treated with ISPI for four cycles. After the treatment, the lesions were eliminated without recurrence during a 12-month follow-up. Our results demonstrate that ISPI can be used as an effective treatment modality for cutaneous fungal granuloma.

Immunotherapy for lung cancer

Treatment of lung cancer remains a challenge, and lung cancer is still the leading cause of cancer-related mortality. Immunotherapy has previously failed in lung cancer but has recently emerged as a very effective new therapy, and there is now growing worldwide enthusiasm in cancer immunotherapy. We summarize why immune checkpoint blockade therapies have generated efficacious and durable responses in clinical trials and why this has reignited interest in this field. Cancer vaccines have also been explored in the past with marginal success. Identification of optimal candidate neoantigens may improve cancer vaccine efficacy and may pave the way to personalized immunotherapy, alone or in combination with other immunotherapy such as immune checkpoint blockade. Understanding the steps in immune recognition and eradication of cancer cells is vital to understanding why previous immunotherapies failed and how current therapies can be used optimally. We hold an optimistic view for the future prospect in lung cancer immunotherapy.

Antitumor activity of a novel small molecule TLR7 agonist via immune response induction and tumor microenvironment modulation

Immunotherapy is emerging as a powerful and active tumor-specific approach against cancer via triggering the immune system. Toll-like receptors (TLRs) are fundamental elements of the immune system, which facilitate our understanding of the innate and adaptive immune pathways. TLR agonists used as single agents can effectively eradicate tumors due to their potent stimulation of innate and adaptive immunity. We examined the effects of a novel adenine type of TLR7 agonists on both innate and adaptive immune activation in vitro and in vivo. We established the local and distant tumor‑bearing mice derived from murine mammary carcinoma cell line (4T1) to model metastatic disease. Our data demonstrated that SZU101 was able to stimulate innate immune cells to release cytokines at the very high level compared with LPS at the same or lower concentration. Locally intratumoral SZU101 injection can elicit a systemic antitumor effect on murine breast tumor model. SZU101 affected the frequency of intratumoral immune cell infiltration, including the percentage of CD4+ and CD8+ increase, and the ratio of Tregs decrease. Our data reveal that the antitumor effect of SZU101 is associated with multiple mechanisms, inducing tumor‑specific immune response, activation of innate immune cells and modulation of the tumor microenvironment.

Linc-POU3F3 promotes cell proliferation in gastric cancer via increasing T-reg distribution

Long noncoding RNA (lncRNA) have been proved to participate in the oncogenesis or development of gastrointestinal tumors. In this study, we aimed to identify the function of lncRNAs in the differentiation of peripheral blood T cells especially the distribution of regulatory T cells (T-reg) in gastric cancer. The distribution of T-reg was detected by flow cytometry. Peripheral blood T-reg cells were significantly up-regulated in plasma samples of gastric cancer patients. LncRNA microarray detection indicated an aberrant expression profiling of lncRNAs in T-reg cells between gastric cancer patients and controls in which linc-POU3F3 was selected as a potential biomarker with the highest fold change value as well as the most stable expression level in each group. In addition, over-expression of linc-POU3F3 elevated Treg distribution in vitro and promoted tumor cell proliferation in the co-culture system. We further found that linc-POU3F3 could recruit TGF-beta which increased the phosphorylation of SMAD2/3. In conclusion, we found that linc-POU3F3 could promote the distribution of Tregs in peripheral blood T cell which caused an enhanced cell proliferation of gastric cancer cells by recruiting TGF-beta as well as activating TGF-beta signal pathway. This finding may provide a theoretical basis for the further exploration of lncRNAs function in immune cell cells of gastric cancer.

CpG Oligonucleotides as Cancer Vaccine Adjuvants

Adjuvants improve host responsiveness to co-delivered vaccines through a variety of mechanisms. Agents that trigger cells expressing Toll-like receptors (TLR) activate an innate immune response that enhances the induction of vaccine-specific immunity. When administered in combination with vaccines designed to prevent or slow tumor growth, TLR agonists have significantly improved the generation of cytotoxic T lymphocytes. Unfortunately, vaccines containing TLR agonists have rarely been able to eliminate large established tumors when administered systemically. To improve efficacy, attention has focused on delivering TLR agonists intra-tumorally with the intent of altering the tumor microenvironment. Agonists targeting TLRs 7/8 or 9 can reduce the frequency of Tregs while causing immunosuppressive MDSC in the tumor bed to differentiate into tumoricidal macrophages thereby enhancing tumor elimination. This work reviews pre-clinical and clinical studies concerning the utility of TLR 7/8/9 agonists as adjuvants for tumor vaccines.