CpG oligodeoxynucleotides as TLR9 agonists: therapeutic applications in cancer

ACE mRNA (Additional Chimeric Element incorporated IVT mRNA) for Enhancing Protein Expression by Modulating Immunogenicity

The development of in vitro transcribed mRNA (IVT mRNA)-based therapeutics/vaccines depends on the management of IVT mRNA immunogenicity. IVT mRNA, which is used for intracellular protein translation, often triggers unwanted immune responses, interfering with protein expression and leading to reduced therapeutic efficacy. Currently, the predominant approach for mitigating immune responses involves the incorporation of costly chemically modified nucleotides like pseudouridine (Ψ) or N1-methylpseudouridine (m1Ψ) into IVT mRNA, raising concerns about expense and the potential misincorporation of amino acids into chemically modified codon sequences. Here, an Additional Chimeric Element incorporated mRNA (ACE mRNA), a novel approach incorporating two segments within a single IVT mRNA structure, is introduced. The first segment retains conventional IVT mRNA components prepared with unmodified nucleotides, while the second, comprised of RNA/DNA chimeric elements, aims to modulate immunogenicity. Notably, ACE mRNA demonstrates a noteworthy reduction in immunogenicity of unmodified IVT mRNA, concurrently demonstrating enhanced protein expression efficiency. The reduced immune responses are based on the ability of RNA/DNA chimeric elements to restrict retinoic acid-inducible gene I (RIG-I) and stimulator of interferon genes (STING)-mediated immune activation. The developed ACE mRNA shows great potential in modulating the immunogenicity of IVT mRNA without the need for chemically modified nucleotides, thereby advancing the safety and efficacy of mRNA-based therapeutics/vaccines.

Exploiting bacterial-origin immunostimulants for improved vaccination and immunotherapy: current insights and future directions

Vaccination is a valid strategy to prevent and control newly emerging and reemerging infectious diseases in humans and animals. However, synthetic and recombinant antigens are poor immunogenic to stimulate efficient and protective host immune response. Immunostimulants are indispensable factors of vaccines, which can promote to trigger fast, robust, and long-lasting immune responses. Importantly, immunotherapy with immunostimulants is increasing proved to be an effective and promising treatment of cancer, which could enhance the function of the immune system against tumor cells. Pattern recognition receptors (PRRs) play vital roles in inflammation and are central to innate and adaptive immune responses. Toll-like receptors (TLRs)-targeting immunostimulants have become one of the hotspots in adjuvant research and cancer therapy. Bacterial-origin immunoreactive molecules are usually the ligands of PRRs, which could be fast recognized by PRRs and activate immune response to eliminate pathogens. Varieties of bacterial immunoreactive molecules and bacterial component-mimicking molecules have been successfully used in vaccines and clinical therapy so far. This work provides a comprehensive review of the development, current state, mechanisms, and applications of bacterial-origin immunostimulants. The exploration of bacterial immunoreactive molecules, along with their corresponding mechanisms, holds immense significance in deepening our understanding of bacterial pathogenicity and in the development of promising immunostimulants.

Nanotechnology Applications in Breast Cancer Immunotherapy

Next-generation cancer treatments are expected not only to target cancer cells but also to simultaneously train immune cells to combat cancer while modulating the immune-suppressive environment of tumors and hosts to ensure a robust and lasting response. Achieving this requires carriers that can codeliver multiple therapeutics to the right cancer and/or immune cells while ensuring patient safety. Nanotechnology holds great potential for addressing these challenges. This article highlights the recent advances in nanoimmunotherapeutic development, with a focus on breast cancer. While immune checkpoint inhibitors (ICIs) have achieved remarkable success and lead to cures in some cancers, their response rate in breast cancer is low. The poor response rate in solid tumors is often associated with the low infiltration of anti-cancer T cells and an immunosuppressive tumor microenvironment (TME). To enhance anti-cancer T-cell responses, nanoparticles are employed to deliver ICIs, bispecific antibodies, cytokines, and agents that induce immunogenic cancer cell death (ICD). Additionally, nanoparticles are used to manipulate various components of the TME, such as immunosuppressive myeloid cells, macrophages, dendritic cells, and fibroblasts to improve T-cell activities. Finally, this article discusses the outlook, challenges, and future directions of nanoimmunotherapeutics.

Lipid Nanoparticle Delivery Alters the Adjuvanticity of the TLR9 Agonist CpG by Innate Immune Activation in Lymphoid Tissue

Pharmacological strategies to activate innate immune cells are of great relevance in the context of vaccine design and anticancer immune therapy, to mount broad immune responses able to clear infection and malignant cells. Synthetic CpG oligodeoxynucleotides (CpG-ODNs) are short single-stranded DNA molecules containing unmethylated CpG dinucleotides and a phosphorothioate backbone. Class B CpG ODNs activate robust innate immune responses through a TLR9-dependent NF-κB signaling pathway. This feature is attractive to exploit in the context of vaccine design and cancer immunotherapy. Soluble CpG-ODNs cause hepatic toxicity, which reduces its therapeutic applicability. The formulation of class B CpG ODN1826 in lipid nanoparticles (LNPs) containing an ionizable cationic lipid that complexes CpG through electrostatic interaction is reported. Upon local administration, LNP-formulated CpG drains to lymph nodes and triggers robust innate immune activation. Unformulated, soluble, CpG, by contrast, is unable to induce robust innate activation in draining lymph nodes and is distributed systemically. In a vaccination setting, LNP-formulated CpG, admixed with a protein antigen, induces higher antigen-specific antibody titers and T cell responses than antigen admixed with unformulated soluble CpG.

Effectiveness of radiotherapy and targeted radionuclide therapy for melanoma in preclinical mouse models: A combination treatments overview

Cutaneous melanoma is an aggressive and highly metastatic skin cancer. In recent years, immunotherapy and targeted small-molecule inhibitors have improved the overall survival of patients. Unfortunately, most patients in advanced stages of disease exhibit either intrinsically resistant or rapidly acquire resistance to these approved treatments. However, combination treatments have emerged to overcome resistance, and novel treatments based on radiotherapy (RT) and targeted radionuclide therapy (TRT) have been developed to treat melanoma in the preclinical mouse model, raising the question of whether synergy in combination therapies may motivate and increase their use as primary treatments for melanoma. To help clarify this question, we reviewed the studies in preclinical mouse models where they evaluated RT and TRT in combination with other approved and unapproved therapies from 2016 onwards, focusing on the type of melanoma model used (primary tumor and or metastatic model). PubMed® was the database in which the search was performed using mesh search algorithms resulting in 41 studies that comply with the inclusion rules of screening. Studies reviewed showed that synergy with RT or TRT had strong antitumor effects, such as tumor growth inhibition and fewer metastases, also exhibiting systemic protection. In addition, most studies were carried out on antitumor response for the implanted primary tumor, demonstrating that more studies are needed to evaluate these combined treatments in metastatic models on long-term protocols.

Breaking the niche: multidimensional nanotherapeutics for tumor microenvironment modulation

Most of the current antitumor therapeutics were developed targeting the cancer cells only. Unfortunately, in the majority of tumors, this single-dimensional therapy is found to be ineffective. Advanced research has shown that cancer is a multicellular disorder. The tumor microenvironment (TME), which is made by a complex network of the bulk tumor cells and other supporting cells, plays a crucial role in tumor progression. Understanding the importance of the TME in tumor growth, different treatment modalities have been developed targeting these supporting cells. Recent clinical results suggest that simultaneously targeting multiple components of the tumor ecosystem with drug combinations can be highly effective. This type of "multidimensional" therapy has a high potential for cancer treatment. However, tumor-specific delivery of such multi-drug combinations remains a challenge. Nanomedicine could be utilized for the tumor-targeted delivery of such multidimensional therapeutics. In this review, we first give a brief overview of the major components of TME. We then highlight the latest developments in nanoparticle-based combination therapies, where one drug targets cancer cells and other drug targets tumor-supporting components in the TME for a synergistic effect. We include the latest preclinical and clinical studies and discuss innovative nanoparticle-mediated targeting strategies.

A first-in-human phase 1 study of cavrotolimod, a TLR9 agonist spherical nucleic acid, in healthy participants: Evidence of immune activation

Introduction

Tumor immunotherapy is designed to control malignancies through the host immune response but requires circumventing tumor-dysregulated immunomodulation through immunostimulation, relieving immunorepression, or a combination of both approaches. Here we designed and characterized cavrotolimod (formerly AST-008), an immunostimulatory spherical nucleic acid (SNA) compound targeting Toll-like receptor 9 (TLR9). We assessed the safety and pharmacodynamic (PD) properties of cavrotolimod in healthy participants in a first-in-human Phase 1 study under protocol AST-008-101 (NCT03086278; https://clinicaltrials.gov/ct2/show/NCT03086278).

Methods

Healthy participants aged 18 to 40 years were enrolled to evaluate four dose levels of cavrotolimod across four cohorts. Each cohort included four participants, and all received a single subcutaneous dose of cavrotolimod. The dose levels were 5, 10, 12.5 and 18.8 µg/kg.

Results and discussion

Cavrotolimod was well tolerated and elicited no serious adverse events or dose limiting toxicities at the doses tested. The results demonstrated that cavrotolimod is a potent innate immune activator, specifically stimulating Th1-type immune responses, and exhibits PD properties that may result in anti-tumor effects in patients with cancer. This study suggests that cavrotolimod is a promising clinical immunotherapy agent.

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.

Development of a Dendritic Cell/Tumor Cell Fusion Cell Membrane Nano-Vaccine for the Treatment of Ovarian Cancer

Ovarian cancer (OC) is a malignant tumor that seriously affects women’s health. In recent years, immunotherapy has shown great potential in tumor treatment. As a major contributor of immunotherapy, dendritic cells (DCs) - based tumor vaccine has been demonstrated to have a positive effect in inducing immune responses in animal experiments. However, the effect of tumor vaccines in clinical trials is not ideal. Therefore, it is urgent to improve the existing tumor vaccines for tumor treatment. Here, we developed a fusion cell membrane (FCM) nano-vaccine FCM-NPs, which is prepared by fusing DCs and OC cells and coating the FCM on the poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) loaded with the immune adjuvant CpG-oligodeoxynucleotide (CpG-ODN). The fusion process promoted the maturation of DCs, thus up-regulating the expression of costimulatory molecule CD80/CD86 and accelerating lymph node homing of DCs. Furthermore, FCM-NPs has both the immunogenicity of tumor cells and the antigen presenting ability of DCs, it can stimulate naive T lymphocytes to produce a large number of tumor-specific cytotoxic CD8⁺ T lymphocytes. FCM-NPs exhibited strong immuno-activating effect both in vitro and in vivo. By establishing subcutaneous transplanted tumor model, patient-derived xenograft tumor model and abdominal metastatic tumor model, FCM-NPs was proved to have the effect of delaying the growth and inhibiting the metastasis of OC. FCM-NPs is expected to become a new tumor vaccine for the treatment of ovarian cancer.

Safety and immunogenicity of SpikoGen®, an advax-cpg55.2-adjuvanted sars-cov-2 spike protein vaccine: a phase 2 randomized placebo-controlled trial in both seropositive and seronegative populations

Objective

We aimed to investigate the immunogenicity and safety of SpikoGen®, a subunit COVID-19 vaccine composed of a recombinant prefusion-stabilized SARS-CoV-2 spike protein combined with the Advax-CpG55.2™ adjuvant, in seronegative and seropositive populations as primary vaccination.

Methods

This randomized, placebo-controlled, double-blind phase 2 trial was conducted on 400 participants randomized 3:1 to receive two doses of 25 μg of SpikoGen® 3 weeks apart or the placebo. The primary safety outcomes were the incidence of solicited adverse events up to 7 days after each dose and unsolicited adverse events up to 28 days after the second dose. The primary immunogenicity outcomes were seroconversion against the S₁ protein and the geometric mean concentration of S₁ antibodies by days 21 and 35.

Results

The SpikoGen® vaccine was well tolerated and no serious adverse events were recorded. The most common solicited adverse events were injection site pain and fatigue, largely graded as mild and transient. By day 35 (2 weeks post second dose), the seroconversion rate against S₁ was 63.55 (95% CI: 57.81–69.01) in the SpikoGen® group versus 7.23 (95% CI: 2.7–15.07) in the placebo group. The geometric mean concentration of S₁ antibodies was 29.12 (95% CI: 24.32–34.87) in the SpikoGen® group versus 5.53 (95% CI: 4.39–6.97) in the placebo group. Previously infected seropositive volunteers showed a large SARS-CoV-2 humoral response after a single SpikoGen® dose.

Discussion

SpikoGen® had an acceptable safety profile and induced promising humoral and cellular immune responses against SARS-CoV-2.

Targeted Delivery of Immunostimulatory CpG Oligodeoxynucleotides to Antigen-Presenting Cells in Draining Lymph Nodes by Stearic Acid Modification and Nanostructurization

Polypod-like structured nucleic acids (polypodnas), which are nanostructured DNAs, are useful for delivering cytosine-phosphate guanine oligodeoxynucleotides (CpG ODNs) to antigen-presenting cells (APCs) expressing Toll-like receptor 9 (TLR9) for immune stimulation. Lipid modification is another approach to deliver ODNs to lymph nodes, where TLR9-positive APCs are abundant, by binding to serum albumin. The combination of these two methods can be useful for delivering CpG ODNs to lymph nodes in vivo. In the present study, CpG1668, a phosphodiester-type CpG ODN, was modified with stearic acid (SA) to obtain SA-CpG1668. Tripodna, a polypodna with three pods, was selected as the nanostructured DNA. Tripodnas loaded with CpG1668 or SA-CpG1668 were obtained in high yields. SA-CpG1668/tripodna bound more efficiently to plasma proteins than CpG1668/tripodna and was more efficiently taken up by macrophage-like RAW264.7 cells than CpG1668/tripodna, whereas the levels of tumor necrosis factor-α released from the cells were comparable between the two. After subcutaneous injection into mice, SA-CpG1668/tripodna induced significantly higher interleukin (IL)-12 p40 production in the draining lymph nodes than SA-CpG1668 or CpG1668/tripodna, with reduced IL-6 levels in plasma. These results indicate that the combination of SA modification and nanostructurization is a useful approach for the targeted delivery of CpG ODNs to lymph nodes.

Intranasal vaccine: Factors to consider in research and development

Most existing vaccines for human use are administered by needle-based injection. Administering vaccines needle-free intranasally has numerous advantages over by needle-based injection, but there are only a few intranasal vaccines that are currently approved for human use, and all of them are live attenuated influenza virus vaccines. Clearly, there are immunological as well as non-immunological challenges that prevent vaccine developers from choosing the intranasal route of administration. We reviewed current approved intranasal vaccines and pipelines and described the target of intranasal vaccines, i.e. nose and lymphoid tissues in the nasal cavity. We then analyzed factors unique to intranasal vaccines that need to be considered when researching and developing new intranasal vaccines. We concluded that while the choice of vaccine formulations, mucoadhesives, mucosal and epithelial permeation enhancers, and ligands that target M-cells are important, safe and effective intranasal mucosal vaccine adjuvants are needed to successfully develop an intranasal vaccine that is not based on live-attenuated viruses or bacteria. Moreover, more effective intranasal vaccine application devices that can efficiently target a vaccine to lymphoid tissues in the nasal cavity as well as preclinical animal models that can better predict intranasal vaccine performance in clinical trials are needed to increase the success rate of intranasal vaccines in clinical trials.

Toll-Like Receptors as a Therapeutic Target in the Era of Immunotherapies

Toll-like receptors (TLRs) are the pattern recognition receptors, which are activated by foreign and host molecules in order to initiate the immune response. They play a crucial role in the regulation of innate immunity, and several studies have shown their importance in bacterial, viral, and fungal infections, autoimmune diseases, and cancers. The consensus view from an immunological perspective is that TLR agonists can serve either as a possible therapeutic agent or as a vaccine adjuvant toward cancers or infectious diseases and that TLR inhibitors may be a promising approach to the treatment of autoimmune diseases, some cancers, bacterial, and viral infections. These notions are based on the fact that TLR agonists stimulate the secretion of proinflammatory cytokines and in general, the development of proinflammatory responses. Some of the TLR-based inhibitory agents have shown to be efficacious in preclinical models and have now entered clinical trials. Therefore, TLRs seem to hold the potential to serve as a perfect target in the era of immunotherapies. We offer a perspective on TLR-based therapeutics that sheds light on their usefulness and on combination therapies. We also highlight various therapeutics that are in the discovery phase or in clinical trials.

Intratumoral injection of TLR9 agonist promotes an immunopermissive microenvironment transition and causes cooperative antitumor activity in combination with anti-PD1 in pancreatic cancer

Background

Complex tumor and immune microenvironment render pancreatic ductal adenocarcinoma (PDAC) resistant to immune checkpoint inhibitors (ICIs). Therefore, a strategy to convert the immune hostile into an immunopermissive tumor is required. Recent studies showed that intratumoral injection of Toll-like receptor 9 agonist IMO-2125 primes the adaptive immune response. Phase I and II trials with intratumoral IMO-2125 demonstrated its safety and antitumoral activity.

Methods

We generated an array of preclinical models by orthotopically engrafting PDAC-derived cell lines in syngeneic mice and categorized them as high, low and no immunogenic potential, based on the ability of tumor to evoke T lymphocyte or NK cell response. To test the antitumor efficacy of IMO-2125 on locally treated and distant sites, we engrafted cancer cells on both flanks of syngeneic mice and treated them with intratumoral IMO-2125 or vehicle, alone or in combination with anti-PD1 ICI. Tumor tissues and systemic immunity were analyzed by transcriptomic, cytofluorimetric and immunohistochemistry analysis.

Results

We demonstrated that intratumoral IMO-2125 as single agent triggers immune system response to kill local and distant tumors in a selected high immunogenic subtype affecting tumor growth and mice survival. Remarkably, intratumoral IMO-2125 in combination with systemic anti-PD1 causes a potent antitumor effect on primary injected and distant sites also in pancreatic cancer models with low immunogenic potential, preceded by a transition toward an immunopermissive microenvironment, with increase in tumor-infiltrating dendritic and T cells in tumor and lymph nodes.

Conclusion

We demonstrated a potent antitumor activity of IMO-2125 and anti-PD1 combination in immunotherapy-resistant PDAC models through the modulation of immune microenvironment, providing the rationale to translate this strategy into a clinical setting.

A simple self-adjuvanting biomimetic nanovaccine self-assembled with the conjugate of phospholipids and nucleotides can induce a strong cancer immunotherapeutic effect

Biomimetic nanoparticles have potential applications in many fields due to their favorable properties. Here, we developed a self-adjuvanting biomimetic anti-tumor nanovaccine, which was self-assembled with an amphiphilic conjugate synthesized with the phospholipids of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and hydrophilic Toll-like receptor (TLR9) agonist CpG ODN. The nanovaccine could not only provide effective initial antigen stimulation and sustained long-term antigen supply with a controlled release, but also induce antigen cross-presentation via the MHC-I pathway initiating CD8+ T-cell responses. Moreover, the dense nucleotide shell around the nanovaccine could promote antigen endocytosis via various receptor-mediated pathways into dendritic cells. CpG ODN interacted with TLR9 triggering the cytokine secretion of TNF-α and IL-10, which further boosted the anti-tumor humoral and cellular immune responses, which led to a significant tumor suppressive effect and remarkable survival prolongation. So, this nanovaccine self-assembled with phospholipid-nucleotide amphiphiles can serve as a safe, simple and efficient approach for anti-tumor immunotherapy.

The synergistic strategies for the immuno-oncotherapy with photothermal nanoagents

Immuno-oncotherapy has shown great promise for the cure of late-stage and metastatic cancer. Great efforts have tried to improve the overall response rate (ORR) and to reduce the immune-related adverse events (irAEs). Antigen presentation, T cell activation and killing are interlocking and distinct steps to initiate effective anti-tumor immune responses. Aiming to overcome the tumor immune evasion whose mechanisms include limited release of neoantigen, suppressed infiltration of antigen-presenting cells (APCs) and T cells, and the expression of immune checkpoints (ICPs), combinational therapeutic strategies have shown great potential by activating the anti-tumor immune responses together with deactivating immunosuppressive conditions simultaneously. In this direction, photothermal therapy (PTT) has attracted attention due to the efficient ablation of tumor cells, of which the released immunogenic tumor debris can activate host immune responses. The combination of immunoadjuvants and/or ICP inhibitors can boost the anti-tumor immune responses, realizing PTT-synergized immuno-oncotherapy. In this regard, numerous multifunctional nanomaterials have been designed with integration of photothermal and immuno-oncotherapeutic agents into one package via well-designed surface modification and functionalization. This review summarizes the recent studies on the synergistic strategies for the immuno-oncotherapy based on photothermal nanoagents and the mechanisms that trigger the systemic anti-tumor immune responses and PTT-synergized immuno-oncotherapy. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

SARS-CoV-2 will constantly sweep its tracks: a vaccine containing CpG motifs in 'lasso' for the multi-faced virus

During the current COVID-19 pandemic, the global ratio between the dead and the survivors is approximately 1 to 10, which has put humanity on high alert and provided strong motivation for the intensive search for vaccines and drugs. It is already clear that if we follow the most likely scenario, which is similar to that used to create seasonal influenza vaccines, then we will need to develop improved vaccine formulas every year to control the spread of the new, highly mutable coronavirus SARS-CoV-2. In this article, using well-known RNA viruses (HIV, influenza viruses, HCV) as examples, we consider the main successes and failures in creating primarily highly effective vaccines. The experience accumulated dealing with the biology of zoonotic RNA viruses suggests that the fight against COVID-19 will be difficult and lengthy. The most effective vaccines against SARS-CoV-2 will be those able to form highly effective memory cells for both humoral (memory B cells) and cellular (cross-reactive antiviral memory T cells) immunity. Unfortunately, RNA viruses constantly sweep their tracks and perhaps one of the most promising solutions in the fight against the COVID-19 pandemic is the creation of 'universal' vaccines based on conservative SARS-CoV-2 genome sequences (antigen-presenting) and unmethylated CpG dinucleotides (adjuvant) in the composition of the phosphorothioate backbone of single-stranded DNA oligonucleotides (ODN), which can be effective for long periods of use. Here, we propose a SARS-CoV-2 vaccine based on a lasso-like phosphorothioate oligonucleotide construction containing CpG motifs and the antigen-presenting unique ACG-containing genome sequence of SARS-CoV-2. We found that CpG dinucleotides are the most rare dinucleotides in the genomes of SARS-CoV-2 and other known human coronaviruses, and hypothesized that their higher frequency could be responsible for the unwanted increased lethality to the host, causing a ‘cytokine storm’ in people who overexpress cytokines through the activation of specific Toll-like receptors in a manner similar to TLR9-CpG ODN interactions. Interestingly, the virus strains sequenced in China (Wuhan) in February 2020 contained on average one CpG dinucleotide more in their genome than the later strains from the USA (New York) sequenced in May 2020. Obviously, during the first steps of the microevolution of SARS-CoV-2 in the human population, natural selection tends to select viral genomes containing fewer CpG motifs that do not trigger a strong innate immune response, so the infected person has moderate symptoms and spreads SARS-CoV-2 more readily. However, in our opinion, unmethylated CpG dinucleotides are also capable of preparing the host immune system for the coronavirus infection and should be present in SARS-CoV-2 vaccines as strong adjuvants.

Class C CpG Oligodeoxynucleotide Immunomodulatory Response in Aged Squirrel Monkey (Saimiri Boliviensis Boliviensis)

One means of stimulating the mammalian innate immune system is via Toll-like receptor 9 (TLR9) being exposed to unmethylated cytosine-phosphate-guanine (CpG) DNA, also known as pathogen-associated molecular patterns (PAMPs) of microbial origin. Synthetic CpG oligodeoxynucleotides (ODNs) with defined CpG motifs possess broad immunostimulatory properties that make CpG ODNs suitable as therapeutic interventions in a variety of human disease conditions, including Alzheimer's disease (AD). Rodent models are often used to preclinically test the effectiveness of CpG ODN therapeutic agents for AD and other disorders. However, the translatability of findings in such models is limited due to the significant difference of the expression of TLR9 between primates and rodents. The squirrel monkey (SQM), a New World non-human primate (NHP), is known to be phylogenetically proximate to humans, and develops extensive age-dependent cerebral amyloid angiopathy (CAA), a key pathological feature of AD. Hence, this model is currently being used to test AD therapeutics. In the present study, we conducted the first examination of Class C CpG ODN's immunomodulatory role in elderly SQMs. We documented the effectiveness of CpG ODN to trigger an immune response in an aged cohort whose immune system is senescent. The specific immune response patterns detected here closely resembled CpG ODN-induced immunostimulatory patterns observed in prior human studies. Overall, our findings provide critical data regarding the immunomodulatory potential of CpG ODN in this NHP model, allowing for future translational studies of innate immunity stimulation via TLR9 agonists for diverse indications, including AD therapeutics.

Dendritic cell activation by an E. coli-derived monophosphoryl lipid A enhances the efficacy of PD-1 blockade

Cancer immunotherapy is a powerful approach for cancer treatment, but its clinical effects rely on the tumor's immune conditions. In particular, low response rates to PD-1 blockades are highly correlated with impaired T cell priming. Here, we demonstrate that E. coli-derived monophosphoryl lipid A (EcML) activates dendritic cells in a toll-like receptor-4 (TLR-4)-dependent manner and increases the sensitivity of cancer cells to anti-PD-1 immunotherapy. EcML is a mixture of 4'-monophosphoryl lipids A (MPLAs) produced directly by an engineered Escherichia coli strain; it has a unique congener composition that differentiates it from the well-established MPLA adjuvants, 3-O-desacyl-4'-monophosphoryl lipid A and glucopyranosyl lipid A. Given that active dendritic cells initiate adaptive immune responses, we investigated the anti-tumor activity of an aqueous formulation of EcML. Upon sensing EcML via TLR-4, dendritic cells matured into powerful antigen-presenting cells that could stimulate naïve T cells. EcML reduced tumor growth in the B16F10 mouse model via dendritic cell activation and potentiated PD-1 blockade therapy in the B16F10-OVA melanoma model. These data identify EcML as a promising TLR-4 agonist that can induce anti-tumor immune responses and potentiate PD-1 blockade therapy against tumors.

IL-15 and a Two-Step Maturation Process Improve Bone Marrow-Derived Dendritic Cell Cancer Vaccine

In the last 20 years, dendritic cells (DCs) have been largely used as a platform for therapeutic vaccination in cancer patients. However, despite its proven safety and ability to induce cancer specific immune responses, the clinical benefits of DC-based immunotherapy are currently very limited. Thus, novel approaches are still needed to boost its efficacy. Our group recently showed that squaric acid treatment of antigens is an important adjuvant that can increase vaccine-induced downstream immune responses and therapeutic outcomes. Here we further improved this dendritic cell vaccine formulation by developing a new method for differentiating and maturing DCs from their bone marrow precursors. Our data demonstrate that bone marrow-derived DCs differentiated with GM-CSF and IL-15 and matured with a maturation cocktail in two steps present a more mature and immunogenic phenotype, compared to standard DC preparations. Further suppression of the prostaglandin E₂ pathway achieved even more immunogenic DC phenotypes. This vaccine was more potent at delaying tumor growth, improved animal survival and induced a more immunogenic and Th1-skewed T cell response in an ovarian cancer mouse model. These promising results support future efforts for the clinical translation of this approach.

BN nanospheres functionalized with mesoporous silica for enhancing CpG oligodeoxynucleotide-mediated cancer immunotherapy

CpG oligodeoxynucleotides (CpG ODNs) possess strong immunostimulatory activity, which hold great promise in cancer immunotherapy. However, their therapeutic efficacy is largely limited due to nuclease degradation and poor cellular internalization. Efficiently delivering CpG ODNs into target cells is crucial to improve their therapeutic efficacy. Boron nitride nanospheres (BNNS) possess advantage as carriers for CpG ODNs. However, their poor aqueous dispersity and low CpG ODN loading capacity became a big obstacle for further applications. Herein, we develop amino group grafted, mesoporous silica (MS)-functionalized BNNS as novel nanovectors for CpG ODN delivery. Modification of BNNS with MS significantly improved the dispersity of BNNS and CpG ODN loading. BNNS@MS-NH2 exhibited no cytotoxicity and enhanced the delivery of CpG ODNs into macrophages. BNNS@MS-NH2/CpG ODN complexes triggered enhanced immunostimulation and induced higher amounts of cytokines. Most importantly, BNNS@MS-NH2/CpG ODN complexes induced bifurcated cytokines, which simultaneously simulated the secretion of IL-6, TNF-α and IFN-α. In contrast, CpG ODN and BNNS/CpG ODN complexes could not. The result of the Transwell plate assay suggested that BNNS@MS-NH2/CpG ODN complexes were more effective in inhibiting cancer cell growth. Taken together, our findings provide a promising strategy for enhancing CpG ODN-mediated cancer immunotherapy.

CpG-PEG Conjugates and their Immune Modulating Effects after Systemic Administration

PURPOSE

Synthetic oligodeoxynucleotides (ODN) containing unmethylated CpG motifs were found to be able to target cells that express Toll-like receptor 9 to modulate innate and adaptive immune reactions. But their in vivo application in immunotherapy against cancer has not been successful. We attempted in this study to examine polyethylene-glycol (PEG) conjugated CpG ODNs and investigated their mechanism of immune modulation in anti-cancer therapy.

METHODS

CpG-PEG conjugates with different PEG lengths were synthesized. In vitro activity as well as in vivo pharmacokinetics and pharmacodynamics properties were evaluated.

RESULTS

CpG-PEG20Ks were found to be able to persist longer in circulation and activate various downstream effector cells. After intravenous injection, they resulted in higher levels of IL-12p70 in the circulation and lower M-MDSC infiltrates in the tumor microenvironment. Such activities were different from those of CpG ODNs without PEGylation, suggesting different PK-PD profiles systemically and locally.

CONCLUSIONS

Our data support the development of CpG-PEGs as a new therapeutic agent that can be systemically administered to modulate immune responses and the microenvironment in tumor tissues.

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.

Codon-Optimized P1A-Encoding DNA Vaccine: Toward a Therapeutic Vaccination against P815 Mastocytoma

DNA vaccine can be modified to increase protein production and modulate immune response. To enhance the efficiency of a P815 mastocytoma DNA vaccine, the P1A gene sequence was optimized by substituting specific codons with synonymous ones while modulating the number of CpG motifs. The P815A murine antigen production was increased with codon-optimized plasmids. The number of CpG motifs within the P1A gene sequence modulated the immunogenicity by inducing a local increase in the cytokines involved in innate immunity. After prophylactic immunization with the optimized vaccines, tumor growth was significantly delayed and mice survival was improved. Consistently, a more pronounced intratumoral recruitment of CD8⁺ T cells and a memory response were observed. Therapeutic vaccination was able to delay tumor growth when the codon-optimized DNA vaccine containing the highest number of CpG motifs was used. Our data demonstrate the therapeutic potential of optimized P1A vaccine against P815 mastocytoma, and they show the dual role played by codon optimization on both protein production and innate immune activation.

In Vitro and In Vivo Stimulation of Toll-Like Receptor 9 by CpG Oligodeoxynucleotides Incorporated Into Polypod-Like DNA Nanostructures

Cytosine-phosphate-guanine (CpG) DNA is known to increase the potency of vaccines. Here, in vitro and in vivo stimulation of toll-like receptor 9 by CpG DNA incorporated into polypod-like DNA nanostructures was evaluated by measuring the levels of tumor necrosis factor alpha released from macrophage-like RAW 264.7 cells and plasma interleukin (IL)-12p40 in vivo following intravenous injection into mice. Phosphodiester CpG1668 was selected as the CpG DNA, and tripodna and hexapodna, which were CpG1668-containing tripod and hexapod-like DNA nanostructures, respectively, were designed. CpG-tripodna and CpG-hexapodna induced tumor necrosis factor alpha release from RAW 264.7 cells about 10- and ∼30-fold higher than single-stranded CpG1668 (CpG-SS). Moreover, in all cases examined, plasma IL-12p40 concentrations increased after intravenous injection into mice, with peak levels depending on the samples and the doses. The area under the plasma concentration-time curves indicated that the CpG-hexapodna was approximately 20-fold more efficient in inducing IL-12p40 production than CpG-SS. The efficiency of CpG-tripodna and CpG-hexapodna to increase the potency of CpG-SS in vivo was comparable to that observed in cultured RAW 264.7 cells. These results provide experimental evidence that in vitro studies can be used to estimate the in vivo immunostimulatory activity of CpG DNA incorporated into DNA nanostructures.

Therapeutic Injection of a C-Type CpG ODN Induced an Antitumor Immune Response in C57/BL6 Mice of Orthotopically Transplanted Hepatocellular Carcinoma

Synthetic CpG oligodeoxynucleotides (ODNs), as TLR9 agonists, have been found to play a possible role in antitumor effect. In order to determine the effect of YW002, known as a C-type CpG ODN, on the treatment of hepatocellular carcinoma (HCC), which is one of the most aggressive carcinomas, we chose to inject YW002 at the doses of 12.5 µg and 25 µg per mouse 7 days post-tumor challenge. The survival rate of mice was recorded every day. On day 14 postinjection, five mice in each group were bled and randomly sacrificed. The level of IFN-γ or TNF-α in the serum was detected and lymphocyte infiltration in the tumor tissue; the ratios of CD8⁺ T cells and CD4⁺ T cells in the spleen of mice were also analyzed. The results indicated that treatment with YW002 could raise the survival rate and delay tumor growth in the mice with orthotopically transplanted HCC. Furthermore, the treatment improved the antitumor immune response through increasing the T-cell infiltration in tumor and the ratio of CD4⁺, CD8⁺, and NK cells in the spleen. In addition, the concentration of IFN-γ was raised, and the level of TGF-β was depressed. Our data suggested that CpG ODN might be a proper medicament in a monotherapeutic regimen for treatment of HCC.

Pulmonary innate inflammatory responses to agricultural occupational contaminants

Agricultural workers are exposed to many contaminants and suffer from respiratory and other symptoms. Dusts, gases, microbial products and pesticide residues from farms have been linked to effects on the health of agricultural workers. Growing sets of data from in vitro and in vivo models demonstrate the role of the innate immune system, especially Toll-like receptor 4 (TLR4) and TLR9, in lung inflammation induced following exposure to contaminants in agricultural environments. Interestingly, inflammation and lung function changes appear to be discordant indicating the complexity of inflammatory responses to exposures. Whereas the recent development of rodent models and exposure systems have yielded valuable data, we need new systems to examine the combined effects of multiple contaminants in order to increase our understanding of farm-exposure-induced negative health effects.

Graphene oxide-chitosan nanocomposites for intracellular delivery of immunostimulatory CpG oligodeoxynucleotides

CpG oligodeoxynucleotides (ODNs) activate innate and adaptive immune responses, and show strong potential as immunotherapeutic agents against various diseases. Benefiting from their unique physicochemical properties, graphene oxide (GO) has recently attracted great attention in nanomedicine. In this study, we developed a novel CpG ODNs delivery system based on GO-chitosan (GO-CS) nanocomposites. GO-CS nanocomposites were prepared by self-assembly of both components via electrostatic interactions. Compared with GO, GO-CS nanocomposites possessed smaller size, positive surface charge and lower cytotoxicity. CpG ODNs were loaded onto GO-CS nanocomposites via electrostatic interactions. GO-CS nanocomposites greatly improved the loading capacity and cellular uptake of CpG ODNs. GO-CS/CpG ODNs complexes further resulted in an enhanced interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) production compared with that of free CpG ODNs and GO/CpG ODNs complexes. Therefore, GO-CS nanocomposites can serve as efficient nanocarriers for enhancing the delivery efficiency of CpG ODNs.

The effect of the TLR9 ligand CpG-oligodeoxynucleotide on the protective immune response to radiation-induced lung fibrosis in mice

CpG-oligodeoxynucleotide (CpG-ODN) is not only reported to protect against airway hyper responsiveness but is also known as a potent vaccine adjuvant for anti-tumor therapy. Little is known about the effect of CpG-ODN in mice with radiation-induced lung fibrosis (RILF), a common late stage form of tissue damage that occurs after thorax radiotherapy (RT). Here, we evaluated the immunomodulatory effects of CpG-ODN on the development of RILF. Mice were divided into four groups: (1) RT, single dose of 12Gy to the whole thorax; (2) CpG, only intraperitoneal injection of CpG-ODN for total 5 weeks; (3) RT+CpG, irradiation plus CpG-ODN treatment before and after irradiation for total 5 weeks; and (4) control (CTL): No RT or CpG-ODN treatment. In this study, we found that CpG-ODN treatment attenuated lung fibrosis and collagen deposition by increasing the number of M1 macrophagocytes, levels of Type-2 cytokines and TGF-β. CpG-ODN administration up-regulated the expression of TLR9 and STAT1 phosphorylation and reversed the expression of Type-2 immune response key transcription factor GATA-3. Activation of the JAK-STAT1 signaling pathway further enhanced M1 macrophage differentiation and Type-1 cytokine production. This study reveals the mitigating effect of early exposure to CpG-ODN on lung injury caused by irradiation in mice. The potential mechanism of action may be related to enhancement of Type-1 immunity. In conclusion, CpG-ODN may be a potential therapeutic target to treat RILF.

Nanodelivery systems for enhancing the immunostimulatory effect of CpG oligodeoxynucleotides

Synthetic oligodeoxynucleotides containing immunostimulatory CpG motif mimic bacterial DNA and are potent activator of innate and adaptive immune responses. Therefore, CpG ODNs have significant potentials as immunotherapeutic agent for treatment of infectious diseases, allergy and cancer. Many clinical trials involving CpG ODNs either used alone or as adjuvant have been initiated. However, delivery of CpG ODNs to target sites still remains a great challenge due to their extreme susceptibility to nuclease degradation in serum and poor cellular uptake. Chemical modification of CpG ODNs backbone can protect them against degradation by nucleases, but have raised concern regarding several severe side effects. Development of efficient CpG ODNs delivery systems to address these issues and enhance their immunostimulatory effect are highly desirable. In recent years, the emergence of nanotechnology has provided unprecedented opportunities to encapsulate CpG ODN into various nanocarriers or synthesize CpG ODNs nanostructures. This review provides an overview of the delivery systems based on nanomaterials and nanostructures newly developed for enhancing the immunostimulatory effect of CpG ODNs, together with a brief discussion on perspectives for future studies in this field.

Systemic delivery of chTNT-3/CpG immunoconjugates for immunotherapy in murine solid tumor models

CpG oligodeoxynucleotides (CpG) potently activate the immune system by mimicking microbial DNA. Conjugation of CpG to chTNT-3, an antibody targeting the necrotic centers of tumors, enabled CpG to accumulate in tumors after systemic delivery, where it can activate the immune system in the presence of tumor antigens. CpG chemically conjugated to chTNT-3 (chTNT-3/CpG) were compared to free CpG in their ability to stimulate the immune system in vitro and reduce tumor burden in vivo. In subcutaneous Colon 26 adenocarcinoma and B16-F10 melanoma models in BALB/c and C57BL/6 mice, respectively, chTNT-3/CpG, free CpG, or several different control constructs were administered systemically. Intraperitoneal injections of chTNT-3/CpG delayed tumor growth and improved survival and were comparable to intratumorally administered CpG. Compared to saline-treated mice, chTNT-3/CpG-treated mice had smaller average tumor volumes by as much as 72% in Colon 26-bearing mice and 79% in B16-bearing mice. Systemically delivered free CpG and CpG conjugated to an isotype control antibody did not reduce tumor burden or improve survival. In this study, chTNT-3/CpG retained immunostimulatory activity of the CpG moiety and enabled delivery to tumors. Because systemically administered CpG rapidly clear the body and do not accumulate into tumors, chTNT-3/CpG provide a solution to the limitations observed in preclinical and clinical trials.

Polyethyleneimine-functionalized boron nitride nanospheres as efficient carriers for enhancing the immunostimulatory effect of CpG oligodeoxynucleotides

CpG oligodeoxynucleotides (ODNs) stimulate innate and adaptive immune responses. Thus, these molecules are promising therapeutic agents and vaccine adjuvants against various diseases. In this study, we developed a novel CpG ODNs delivery system based on polyethyleneimine (PEI)-functionalized boron nitride nanospheres (BNNS). PEI was coated on the surface of BNNS via electrostatic interactions. The prepared BNNS–PEI complexes had positive zeta potential and exhibited enhanced dispersity and stability in aqueous solution. In vitro cytotoxicity assays revealed that the BNNS–PEI complexes with concentrations up to 100 μg/mL exhibited no obvious cytotoxicity. Furthermore, the positively charged surface of the BNNS–PEI complexes greatly improved the loading capacity and cellular uptake efficiency of CpG ODNs. Class B CpG ODNs loaded on the BNNS–PEI complexes enhanced the production of interleukin-6 and tumor necrosis factor-α from peripheral blood mononuclear cells compared with CpG ODNs directly loaded on BNNS. Contrary to the free CpG ODNs or CpG ODNs directly loaded on BNNS, class B CpG ODNs loaded on the BNNS–PEI complexes induced interferon-α simultaneously. PEI coating may have changed the physical form of class B CpG ODNs on BNNS, which further affected their interaction with Toll-like receptor 9 and induced interferon-α. Therefore, BNNS–PEI complexes can be used to enhance the immunostimulatory effect and therapeutic activity of CpG ODNs and the treatment of diseases requiring interleukin-6, tumor necrosis factor-α, and interferon-α.

Effect of amino groups of mesoporous silica nanoparticles on CpG oligodexynucleotide delivery

In this study, we proposed to modify mesoporous silica nanoparticles (MSNs) with 3-aminopropyltriethoxysilane (NH2-TES), aminoethylaminopropyltriethoxysilane (2NH2-TES) and 3-[2-(2-aminoethylamino)ethylamino] propyl-trimethoxysilane (3NH2-TES) for binding of cytosine-phosphate-guanosine oligodexynucleotides (CpG ODN), and investigated the effect of different amino groups of MSNs on the CpG ODN delivery. Serum stability, in vitro cytotoxicity, and cytokine interleukin-6 (IL-6) induction by MSN-NH2/CpG, MSN-2NH2/CpG and MSN-3NH2/CpG complexes were investigated in detail. The results showed that three kinds of aminated-MSN-based CpG ODN delivery systems had no cytotoxicity to RAW264.7 cells, and binding of CpG ODN to MSN-NH2, MSN-2NH2 and MSN-3NH2 nanoparticles enhanced the serum stability of CpG ODN due to protection by the nanoparticles. However, three aminated MSN-based CpG ODN delivery systems exhibited different CpG ODN delivery efficiency, and MSN-NH2/CpG complexes had the highest ability to induce IL-6 secretion.

Pharmacokinetic Profile and Acute Toxicological Properties of a Novel Radiosensitizer Cytosine-Phosphate-Guanosine Oligodeoxynucleotide 107 in Mice Following Intravenous and Orthotopic Administration

The synthetic cytosine-phosphate-guanosine oligodeoxynucleotide 107 (CpG ODN107) is a novel radiosensitizer for glioma treatment. However, the information related to its pharmacokinetics and toxicity remains unclear. Therefore, the plasma pharmacokinetics, distribution, elimination, and acute toxicity of CpG ODN107 in mice were investigated in the present experiments. The results from the liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay showed that the plasma elimination half-life (t1/2β) of CpG ODN107 in BALB/c mice varied slightly with the dose, and it was 0.65, 0.49, and 0.50 h at the intravenous doses of 2.5, 5, and 10 mg/kg, respectively. CpG ODN107 rapidly and widely distributed in organs/tissues, except the brain and testes. The highest concentrations were found in the liver (28.6% of the administered dose after 0.5 h) and the kidneys (5.7% of the administered dose after 1 h). CpG ODN107 (0.3, 3, and 30 μg/mL) could highly bind to human and mouse plasma proteins in vitro. CpG ODN107 in the forms of prototype was excreted in urine (1.79%) and feces (0.91%), and its shortened metabolites were excreted in urine (2.1%) and feces (2.2%) within the first 24 h. The mice in vivo optical image showed CpG ODN107 labeled with Alexa Fluor 680 fluorochrome (AF680) accumulated in the brain after orthotopic injection, eliminated very slowly, and excreted in urine compared with poly T labeled with AF680. The median lethal dose (LD50) of CpG ODN107 was 75.7 mg/kg for mice; this dose only could produce apparent spleen and liver damage, in line with the distribution features of CpG ODN. In conclusion, our present pharmacokinetic and toxicity investigation will provide helpful information to further pharmacodynamic and pharmacokinetic research of CpG ODN107 and other oligodeoxynucleotide drugs in the future.

Liposome-encapsulated CpG enhances antitumor activity accompanying the changing of lymphocyte populations in tumor via intratumoral administration

Although oligodeoxynucleotides containing CpG motifs (CpG-ODN) are potent immune stimulators, the use of natural CpG-ODN--phosphodiester-backbone CpG--has been limited due to its instability by nuclease in vivo. The aim of this study is to investigate the anticancer efficiency of CpG-ODN capsulated using liposome, which enhances the stability of CpG-ODN. We formulated lipoplex, encapsulated natural CpG-ODN from Mycobacterium bovis with liposome, and tested its immune stimulatory activity in vitro and in vivo. The lipoplex induced a systemic innate immune response in vivo and stimulated dendritic cells, but not macrophages, to stimulate proinflammatory cytokines such as tumor necrosis factor alpha and interleukin-6 in vitro. As expected, the lipoplex effectively mediated the prolonged cancer-therapeutic activity against B16 melanoma, which was dependent on natural killer and CD8(+) T cells. The therapeutic activity was observed after only intratumoral administration of lipoplex among several treatment routes. Intratumoral treatment of lipoplex significantly increased the populations of natural killer and CD8(+) T cells and reduced regulatory CD4(+) T cell recruitment, which was correlated with expression profiles of chemokines (CCL1, CCL3, CXCL1, CXCL10, and CCL22). The antitumor therapeutic effect of lipoplex was dependent on the altered lymphocyte population that might be developed by the profile of intratumoral chemokine expression.

Intraperitoneal and subcutaneous injections of the TLR9 agonist ODN 1668 in rats: brain inflammatory responses are related to peripheral IL-6 rather than interferons

Subcutaneous or intraperitoneal administration of Toll-like receptor (TLR)-9 agonist, ODN 1668 caused moderate fever and anorexia. In comparison to stimulation of other intracellular TLRs, activation of TLR9 did not result in pronounced peripheral induction of interferons, but rather induced interleukin-6. Expression of cytokines (TNFα, IL-1β) and inducible forms of enzymes for prostaglandin E2 synthesis occurred in the brain, in conjunction with a moderate activation of the transcription factors STAT3 and NF-IL6 in brain endothelial cells. The lack of a septic-like state in ODN 1668-treated rats reinforces the therapeutic value of this drug.

Combinatorial photothermal and immuno cancer therapy using chitosan-coated hollow copper sulfide nanoparticles

Near-infrared light-responsive inorganic nanoparticles have been shown to enhance the efficacy of cancer photothermal ablation therapy. However, current nanoparticle-mediated photothermal ablation is more effective in treating local cancer at the primary site than metastatic cancer. Here, we report the design of a near-infrared light-induced transformative nanoparticle platform that combines photothermal ablation with immunotherapy. The design is based on chitosan-coated hollow CuS nanoparticles that assemble the immunoadjuvants oligodeoxynucleotides containing the cytosine-guanine (CpG) motifs. Interestingly, these structures break down after laser excitation, reassemble, and transform into polymer complexes that improve tumor retention of the immunotherapy. In this "photothermal immunotherapy" approach, photothermal ablation-induced tumor cell death reduces tumor growth and releases tumor antigens into the surrounding milieu, while the immunoadjuvants potentiate host antitumor immunity. Our results indicated that combined photothermal immunotherapy is more effective than either immunotherapy or photothermal therapy alone against primary treated and distant untreated tumors in a mouse breast cancer model. These hollow CuS nanoparticles are biodegradable and can be eliminated from the body after laser excitation.

Adjuvant-carrying synthetic vaccine particles augment the immune response to encapsulated antigen and exhibit strong local immune activation without inducing systemic cytokine release

Augmentation of immunogenicity can be achieved by particulate delivery of an antigen and by its co-administration with an adjuvant. However, many adjuvants initiate strong systemic inflammatory reactions in vivo, leading to potential adverse events and safety concerns. We have developed a synthetic vaccine particle (SVP) technology that enables co-encapsulation of antigen with potent adjuvants. We demonstrate that co-delivery of an antigen with a TLR7/8 or TLR9 agonist in synthetic polymer nanoparticles results in a strong augmentation of humoral and cellular immune responses with minimal systemic production of inflammatory cytokines. In contrast, antigen encapsulated into nanoparticles and admixed with free TLR7/8 agonist leads to lower immunogenicity and rapid induction of high levels of inflammatory cytokines in the serum (e.g., TNF-α and IL-6 levels are 50- to 200-fold higher upon injection of free resiquimod (R848) than of nanoparticle-encapsulated R848). Conversely, local immune stimulation as evidenced by cellular infiltration of draining lymph nodes and by intranodal cytokine production was more pronounced and persisted longer when SVP-encapsulated TLR agonists were used. The strong local immune activation achieved using a modular self-assembling nanoparticle platform markedly enhanced immunogenicity and was equally effective whether antigen and adjuvant were co-encapsulated in a single nanoparticle formulation or co-delivered in two separate nanoparticles. Moreover, particle encapsulation enabled the utilization of CpG oligonucleotides with the natural phosphodiester backbone, which are otherwise rapidly hydrolyzed by nucleases in vivo. The use of SVP may enable clinical use of potent TLR agonists as vaccine adjuvants for indications where cellular immunity or robust humoral responses are required.

Pre-conditioning with synthetic CpG-oligonucleotides attenuates myocardial ischemia/reperfusion injury via IL-10 up-regulation

The aim of the study was to investigate whether pre-conditioning with CpG-oligodeoxynucleotides (CpG-ODN) may change cardiac ischemia/reperfusion (I/R)-dependent inflammation and modulates infarct size and cardiac performance. WT and TLR9-deficient mice were pre-treated with 1668-, 1612- and H154-thioate or D-Gal as control. Priming with 1668-thioate significantly induced inflammatory mediators in the serum and a concomitant increase of immune cells in the blood and spleen of WT mice. Furthermore, it induced myocardial pattern recognition receptors and pro-inflammatory cytokines peaking 2 h after priming and a continuous increase of IL-10. 16 h after pre-conditioning, myocardial ischemia was induced for 1 h. Infarct size determined after 24 h of I/R was reduced by 75 % due to pre-conditioning with 1668-thioate but not in the other groups. During reperfusion, cytokine expression in 1668-thioate primed mice increased further with IL-10 exceeding the other mediators by far. These changes were observed neither in animals pre-treated with 1612- or H154-thioate nor in TLR9-deficient mice. The 1668-thioate-dependent increase of IL-10 was further supported by results of a micro-array analysis 3 h after begin of reperfusion. Block of IL-10 signaling increased I/R size and prevented influence of priming. In the group pre-treated with 1668-thioate, cardiac function was preserved 24 h, 14 days and 28 days after I/R, whereas animals without pre-conditioning exhibited impaired heart function 24 h and 14 days after I/R. The excessive 1668-thioate-dependent IL-10 up-regulation during pre-conditioning and after I/R seems to be the key factor for reducing infarct size and improving cardiac function. This is in agreement with the finding that IL-10 block prevents cardioprotection by pre-conditioning.

A randomized pilot phase I study of modified carcinoembryonic antigen (CEA) peptide (CAP1-6D)/montanide/GM-CSF-vaccine in patients with pancreatic adenocarcinoma

Background

CEA is expressed in >90% of pancreatic cancers (PC) and may be an appropriate immunotherapy target. CEA is poorly immunogenic due to immune tolerance; CAP1-6D, an altered peptide ligand can help bypass tolerance. We conducted a pilot randomized phase I trial in PC patients to determine the peptide dose required to induce an optimal CD8⁺ T cell response.

Methods

Patients with a PS 0-1, HLA-A2+ and CEA-expressing, previously-treated PC were randomized to receive 10 μg (arm A), 100 μg (arm B) or 1000 μg (arm C) of CEA peptide emulsified in Montanide and GM-CSF, given every 2 weeks until disease progression.

Results

Sixty-six patients were screened and 19 enrolled of whom 14 received at least 3 doses of the vaccine and thus evaluated for the primary immunologic endpoint. A median of 4 cycles (range 1-81) was delivered. Median and mean peak IFN-γ T cell response by ELISPOT (spots per 10⁴ CD8⁺ cells, Arm A/B/C) was 11/52/271 (A vs. C, p = 0.028) for medians and 37/148/248 (A vs. C, p = 0.032) for means. T cell responses developed or increased in 20%/60%/100% of pts in Arms A/B/C. Seven of the 19 patients remain alive at a minimum 32 months from trial initiation, including three with unresectable disease.

Conclusions

The T cell response in this randomized phase I trial was dose-dependent with the 1 mg CEA peptide dose eliciting the most robust T cell responses. A signal of clinical benefit was observed and no significant toxicity was noted. Further evaluation of 1 mg CEA peptide with stronger adjuvants, and/or combined with agents to overcome immune inhibitory pathways, may be warranted in PC pts.

Trial registration

ClinicalTrials.gov NCT00203892

Gold nanoparticle delivery of modified CpG stimulates macrophages and inhibits tumor growth for enhanced immunotherapy

Gold nanoparticle accumulation in immune cells has commonly been viewed as a side effect for cancer therapeutic delivery; however, this phenomenon can be utilized for developing gold nanoparticle mediated immunotherapy. Here, we conjugated a modified CpG oligodeoxynucleotide immune stimulant to gold nanoparticles using a simple and scalable self-assembled monolayer scheme that enhanced the functionality of CpG in vitro and in vivo. Nanoparticles can attenuate systemic side effects by enhancing CpG delivery passively to innate effector cells. The use of a triethylene glycol (TEG) spacer on top of the traditional poly-thymidine spacer increased CpG macrophage stimulatory effects without sacrificing DNA content on the nanoparticle, which directly correlates to particle uptake. In addition, the immune effects of modified CpG-AuNPs were altered by the core particle size, with smaller 15 nm AuNPs generating maximum immune response. These TEG modified CpG-AuNP complexes induced macrophage and dendritic cell tumor infiltration, significantly inhibited tumor growth, and promoted survival in mice when compared to treatments with free CpG.

Chitosan-coated boron nitride nanospheres enhance delivery of CpG oligodeoxynucleotides and induction of cytokines

BACKGROUND

Cytosine-phosphate-guanine (CpG) oligodeoxynucleotides activate Toll-like receptor 9, leading to induction of proinflammatory cytokines, which play an important role in induction and maintenance of innate and adaptive immune responses. Previously, we have used boron nitride nanospheres (BNNS) as a carrier for delivery of unmodified CpG oligodeoxynucleotides to activate Toll-like receptor 9. However, because CpG oligodeoxynucleotides and BNNS are both negatively charged, electrostatic repulsion between them is likely to reduce the loading of CpG oligodeoxynucleotides onto BNNS. Therefore, the efficiency of uptake of CpG oligodeoxynucleotides is also limited and does not result in induction of a robust cytokine response. To ameliorate these problems, we developed a CpG oligodeoxynucleotide delivery system using chitosan-coated BNNS as a carrier.

METHODS

To facilitate attachment of CpG oligodeoxynucleotides onto the BNNS and improve their loading capacity, we prepared positively charged BNNS by coating them with chitosan preparations of three different molecular weights and used them as carriers for delivery of CpG oligodeoxynucleotides.

RESULTS

The zeta potentials of the BNNS-CS complexes were positive, and chitosan coating improved their dispersity and stability in aqueous solution compared with BNNS. The positive charge of the BNNS-CS complexes greatly improved the loading capacity and cellular uptake efficiency of CpG oligodeoxynucleotides. The loading capacity of the CpG oligodeoxynucleotides depended on the molecular weight of chitosan, which affected the positive charge density on the surface of the BNNS. CpG oligodeoxynucleotides loaded onto BNNS-CS complexes significantly enhanced production of interleukin-6 and tumor necrosis factor-α by peripheral blood mononuclear cells compared with CpG oligodeoxynucleotides directly loaded onto BNNS, or when Lipofectamine™ 2000 was used as the carrier. The molecular weight of the chitosan used to coat the BNNS affected the magnitude of cytokine induction by varying the strength of condensation of the CpG oligodeoxynucleotides.

CONCLUSION

Although the loading capacity of BNNS coated with low molecular weight chitosan preparations was the lowest of all the preparations, they induced the highest levels of cytokines.

[Immunotherapy for non-small cell lung cancer--novel approaches to improve patient outcome]

简介

通常，非小细胞肺癌（non-small cell lung cancer, NSCLC）诊断已为晚期，且预后较差。目前的NSCLC标准治疗总体治愈率低，有必要开发新的治疗方法。我们在本综述中提供了最新的免疫治疗干预临床数据，该手段可能能够提高免疫系统对细胞的应答。

方法

我们针对临床应用免疫疗法治疗NSCLC，检索了PubMed上的文章以及最近肿瘤学术会议上的摘要。

结果

Ⅱ期临床研究结果表明，靶向肿瘤细胞本身或其异常表达的肿瘤标志物的疫苗治疗（mucin1，黑色素瘤相关抗原3，或表皮生长因子），有望作为NSCLC免疫疗法。非抗原免疫治疗，如抗细胞毒T淋巴细胞抗原4单克隆抗体、talactoferrin alfa和toll-样受体9拮抗剂，作用于激活的免疫系统，与肿瘤抗原无关，可用于晚期NSCLC的治疗。目前一些免疫治疗正在进行Ⅲ期研究，以确定最佳治疗方案，并与NSCLC标准治疗对照，确定其临床疗效。

结论

越来越多的证据表明肺部肿瘤存在免疫应答。免疫治疗，包括疫苗治疗和非抗原免疫调节方法，可改善NSCLC的预后。而且，提高抗肿瘤免疫应答的治疗，与化疗有协同作用。生物标志物的明确以及免疫治疗作用机制的进一步阐明对于确定哪些患者更可能从免疫治疗中获益至关重要。

Oligodeoxynucleotides expressing polyguanosine motifs promote antitumor activity through the upregulation of IL-2

The primary goal of cancer immunotherapy is to elicit an immune response capable of eliminating the tumor. One approach toward accomplishing that goal uses general (rather than tumor-specific) immunomodulatory agents to boost the number and activity of pre-existing CTLs. We find that the intratumoral injection of polyguanosine (poly-G) oligonucleotides (ODN) has such an effect, boosting antitumor immunity and promoting tumor regression. The antitumor activity of poly-G ODN was mediated through CD8 T cells in a TLR9-independent manner. Mechanistically, poly-G ODN directly induced the phosphorylation of Lck (an essential element of the T cell-signaling pathway), thereby enhancing the production of IL-2 and CD8 T cell proliferation. These findings establish poly-G ODN as a novel type of cancer immunotherapy.

Patient-tailored modulation of the immune system may revolutionize future lung cancer treatment

Cancer research has devoted most of its energy over the past decades on unraveling the control mechanisms within tumor cells that govern its behavior. From this we know that the onset of cancer is the result of cumulative genetic mutations and epigenetic alterations in tumor cells leading to an unregulated cell cycle, unlimited replicative potential and the possibility for tissue invasion and metastasis. Until recently it was often thought that tumors are more or less undetected or tolerated by the patient’s immune system causing the neoplastic cells to divide and spread without resistance. However, it is without any doubt that the tumor environment contains a wide variety of recruited host immune cells. These tumor infiltrating immune cells influence anti-tumor responses in opposing ways and emerges as a critical regulator of tumor growth. Here we provide a summary of the relevant immunological cell types and their complex and dynamic roles within an established tumor microenvironment. For this, we focus on both the systemic compartment as well as the local presence within the tumor microenvironment of late-stage non-small cell lung cancer (NSCLC), admitting that this multifaceted cellular composition will be different from earlier stages of the disease, between NSCLC patients. Understanding the paradoxical role that the immune system plays in cancer and increasing options for their modulation may alter the odds in favor of a more effective anti-tumor immune response. We predict that the future standard of care of lung cancer will involve patient-tailor-made combination therapies that associate (traditional) chemotherapeutic drugs and biologicals with immune modulating agents and in this way complement the therapeutic armamentarium for this disease.