The future of CpG immunotherapy in cancer

Nanomedicine for T-Cell Mediated Immunotherapy

T-cell immunotherapy offers outstanding advantages in the treatment of various diseases, and with the selection of appropriate targets, efficient disease treatment can be achieved. T-cell immunotherapy has made great progress, but clinical results show that only a small proportion of patients can benefit from T-cell immunotherapy. The extensive mechanistic work outlines a blueprint for using T cells as a new option for immunotherapy, but also presents new challenges, including the balance between different fractions of T cells, the inherent T-cell suppression patterns in the disease microenvironment, the acquired loss of targets, and the decline of T-cell viability. The diversity, flexibility, and intelligence of nanomedicines give them great potential for enhancing T-cell immunotherapy. Here, how T-cell immunotherapy strategies can be adapted with different nanomaterials to enhance therapeutic efficacy is discussed. For two different pathological states, immunosuppression and immune activation, recent advances in nanomedicines for T-cell immunotherapy in diseases such as cancers, rheumatoid arthritis, systemic lupus erythematosus, ulcerative colitis, and diabetes are summarized. With a focus on T-cell immunotherapy, this review highlights the outstanding advantages of nanomedicines in disease treatment, and helps advance one's understanding of the use of nanotechnology to enhance T-cell immunotherapy.

Emerging nanoparticle platforms for CpG oligonucleotide delivery

Unmethylated cytosine-phosphate-guanine (CpG) oligodeoxynucleotides (ODNs), which were therapeutic DNA with high immunostimulatory activity, have been applied in widespread applications from basic research to clinics as therapeutic agents for cancer immunotherapy, viral infection, allergic diseases and asthma since their discovery in 1995. The major factors to consider for clinical translation using CpG motifs are the protection of CpG ODNs from DNase degradation and the delivery of CpG ODNs to the Toll-like receptor-9 expressed human B-cells and plasmacytoid dendritic cells. Therefore, great efforts have been devoted to the advances of efficient delivery systems for CpG ODNs. In this review, we outline new horizons and recent developments in this field, providing a comprehensive summary of the nanoparticle-based CpG delivery systems developed to improve the efficacy of CpG-mediated immune responses, including DNA nanostructures, inorganic nanoparticles, polymer nanoparticles, metal-organic-frameworks, lipid-based nanosystems, proteins and peptides, as well as exosomes and cell membrane nanoparticles. Moreover, future challenges in the establishment of CpG delivery systems for immunotherapeutic applications are discussed. We expect that the continuously growing interest in the development of CpG-based immunotherapy will certainly fuel the excitement and stimulation in medicine research.

Bispecific T cell-engager targeting oncofetal chondroitin sulfate induces complete tumor regression and protective immune memory in mice

BACKGROUND

The malaria protein VAR2CSA binds oncofetal chondroitin sulfate (ofCS), a unique chondroitin sulfate, expressed on almost all mammalian cancer cells. Previously, we produced a bispecific construct targeting ofCS and human T cells based on VAR2CSA and anti-CD3 (V-aCD3^Hu). V-aCD3^Hu showed efficacy against xenografted tumors in immunocompromised mice injected with human immune cells at the tumor site. However, the complex effects potentially exerted by the immune system as a result of the treatment cannot occur in mice without an immune system. Here we investigate the efficacy of V-aCD3^Mu as a monotherapy and combined with immune checkpoint inhibitors in mice with a fully functional immune system.

METHODS

We produced a bispecific construct consisting of a recombinant version of VAR2CSA coupled to an anti-murine CD3 single-chain variable fragment. Flow cytometry and ELISA were used to check cell binding capabilities and the therapeutic effect was evaluated in vitro in a killing assay. The in vivo efficacy of V-aCD3^Mu was then investigated in mice with a functional immune system and established or primary syngeneic tumors in the immunologically "cold" 4T1 mammary carcinoma, B16-F10 malignant melanoma, the pancreatic KPC mouse model, and in the immunologically "hot" CT26 colon carcinoma model.

RESULTS

V-aCD3^Mu had efficacy as a monotherapy, and the combined treatment of V-aCD3^Mu and an immune checkpoint inhibitor showed enhanced effects resulting in the complete elimination of solid tumors in the 4T1, B16-F10, and CT26 models. This anti-tumor effect was abscopal and accompanied by a systemic increase in memory and activated cytotoxic and helper T cells. The combined treatment also led to a higher percentage of memory T cells in the tumor without an increase in regulatory T cells. In addition, we observed partial protection against re-challenge in a melanoma model and full protection in a breast cancer model.

CONCLUSIONS

Our findings suggest that V-aCD3^Mu combined with an immune checkpoint inhibitor renders immunologically "cold" tumors "hot" and results in tumor elimination. Taken together, these data provide proof of concept for the further clinical development of V-aCD3 as a broad cancer therapy in combination with an immune checkpoint inhibitor.

DNA Nanoclusters Combined with One-Shot Radiotherapy Augment Cancer Immunotherapy Efficiency

Immunotherapy shows immense promise for improving cancer treatment. Combining immunotherapy with radiotherapy provides a conspicuous advantage due to its enhanced abscopal effect. However, established immune tolerance mechanisms in the tumor microenvironment can hamper the generation of a sufficient abscopal effect. Herein, a type of DNA nanocluster (DNAnc) that is self-assembled by a CpG-ODNs-loaded Y-shaped double-stranded DNA vector based on the unique complementary base-pairing rules is designed. The unique structure of DNAnc makes it load more than ≈8125.5 ± 822.5 copies of CpG ODNs within one single nanostructure, which effectively increases resistance to nuclease degradation and elevates the efficiency of repolarizing macrophages to an M1-like phenotype. Mechanistic studies reveal that more DNAncs are endocytosed by macrophages in the cancer tissue and repolarized macrophages to elicit a robust abscopal effect with the accumulation of macrophages induced by radiotherapy, generating potent, long-term, and durable antitumor immunity for the inhibition of tumor metastasis and the prevention of tumor recurrence, which provides a novel strategy to boost cancer immunotherapy.

Role of Nanomedicine-Based Therapeutics in the Treatment of CNS Disorders

Central nervous system disorders, especially neurodegenerative diseases, are a public health priority and demand a strong scientific response. Various therapy procedures have been used in the past, but their therapeutic value has been insufficient. The blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier is two of the barriers that protect the central nervous system (CNS), but are the main barriers to medicine delivery into the CNS for treating CNS disorders, such as brain tumors, Parkinson's disease, Alzheimer's disease, and Huntington's disease. Nanotechnology-based medicinal approaches deliver valuable cargos targeting molecular and cellular processes with greater safety, efficacy, and specificity than traditional approaches. CNS diseases include a wide range of brain ailments connected to short- and long-term disability. They affect millions of people worldwide and are anticipated to become more common in the coming years. Nanotechnology-based brain therapy could solve the BBB problem. This review analyzes nanomedicine's role in medication delivery; immunotherapy, chemotherapy, and gene therapy are combined with nanomedicines to treat CNS disorders. We also evaluated nanotechnology-based approaches for CNS disease amelioration, with the intention of stimulating the immune system by delivering medications across the BBB.

The exploration of new biomarkers for oral cancer through the ceRNA network and immune microenvironment analysis

The competitive endogenous RNA (ceRNA) and tumor-penetrating immune cells may be related to the prognosis of oral cancer. However, few studies have focused on the correlation between ceRNAs and immune cells. Thus, we developed a method based on a ceRNA network and tumor-infiltrating immune cells to elucidate the molecular pathways that may predict prognosis in patients with oral cancer. Download RNAseq expression data of oral cancer and control samples from the Cancer Genome Atlas (TCGA), obtain differentially expressed genes and establish a ceRNA network. The cox analysis and lasso regression analysis were used to screen key RNAs to establish a prognostic risk assessment model, and draw a 1.3.5-year forecast nomogram. Then the CIBERSORT algorithm was used to screen important tumor immune infiltrating cells associated with oral cancer. Another prognostic predictive model related to immune cells was established. Finally, co-expression analysis was applied to explore the relationship between key genes in the ceRNA network and important immune cells. Multiple external data sets are used to test the expression of key biomarkers. We constructed prognostic risk models of ceRNA and immune cells, which included 9 differentially expressed mRNAs and 2 types of immune cells. It was discovered from the co-expression analysis that a pair of important biomarkers were associated with the prognosis of oral cancer. T cells regulatory and CGNL1 (R = 0.39, P < .001) showed a significant positive correlation. External data set validation also supports this result. In this study, we found that some crucial ceRNAs (GGCT, TRPS1, CGNL1, HENMT1, LCE3A, S100A8, ZNF347, TMEM144, TMEM192) and immune cells (T cells regulatory and Eosinophils) may be related to the prognosis of oral cancer.

Nanomaterials and Advances in Tumor Immune-Related Therapy: A Bibliometric Analysis

With the rapid growth of the research content of nanomaterials and tumor immunity, the hot spots and urgent problems in the field become blurred. In this review, noticing the great development potential of this research field, we collected and sorted out the research articles from The Clarivate Analytics Web of Science (WOS) Core Collection database in the field over the past 20 years. Next, we use Excel 2019 from Microsoft (Microsoft Corp, Redmond,WA, USA), VOSviewer (version 1.6.18, Leiden University, Leiden, Netherlands), CiteSpace (Chaomei Chen, Drexel University, USA) and other softwares to conduct bibliometric analysis on the screened literatures. This paper not only analyzes the countries, institutions and authors with outstanding contributions in the current research field, but also comes up with the hot spots of current research. We hope that by analyzing and sorting out the past data, we can provide help for the current clinical work and future scientific research.

The Biocomplex Assembled from Antigen Peptide and Toll-like Receptor Agonist Improved the Immunity against Pancreatic Adenocarcinoma In Vivo

Purpose

One of the biggest challenges in cancer immunotherapy is generating robust cancer-specific immunity. This work describes using a biocomplex assembled from a toll-like receptor agonist CpG oligodeoxynucleotide 1826 (CpG) and a pancreatic cancer antigen peptide mesothelin for tuning pancreatic tumor immunity.

Methods

This biocomplex was assembled via electrostatic interactions and characterized in size, morphology, zeta potential, and cargo loading. The effect of biocomplex on cell viability and activation of DCs and macrophages were measured by flow cytometry. The production of cytokines (GM-CSF, TNF, and IL-6) was evaluated by using ELISA kits. The effect of biocomplex on tumor cell proliferation was also evaluated by in vivo tumor model.

Result

We can modulate the surface charge of the biocomplex by simply varying the ratios of the two components. In cell models, this biocomplex did not impact cell viability in the antigen-presenting cell (i.e., dendritic cell and macrophage)-directed immunity. Moreover, this biocomplex regulated the secretion of tumor-related cytokines (i.e., GM-CSF, TNF, and IL-6) and promoted the activation of immune cell surface markers (i.e., CD80+, CD86+, and CD40+). In the mouse model, the biocomplex inhibited the tumor burden effectively and promoted the production of effector cytokines.

Conclusion

The present studies showed that the biocomplex with antigen peptide and toll-like receptor agonist was able to potentiate the antitumor immunity in vivo. This study will help understanding of immunity in pancreatic cancer and developing new immune therapeutic strategies for pancreatic adenocarcinoma.

The role of key gut microbial metabolites in the development and treatment of cancer

In recent years, the role of gut microbial metabolites on the inhibition and progression of cancer has gained significant interest in anticancer research. It has been established that the gut microbiome plays a pivotal role in the development, treatment and prognosis of different cancer types which is often mediated through the gut microbial metabolites. For instance, gut microbial metabolites including bacteriocins, short-chain fatty acids and phenylpropanoid-derived metabolites have displayed direct and indirect anticancer activities through different molecular mechanisms. Despite the reported anticancer activity, some gut microbial metabolites including secondary bile acids have exhibited pro-carcinogenic properties. This review draws a critical summary and assessment of the current studies demonstrating the carcinogenic and anticancer activity of gut microbial metabolites and emphasises the need to further investigate the interactions of these metabolites with the immune system as well as the tumour microenvironment in molecular mechanistic and clinical studies.

Reversing tumor immunosuppressive microenvironment via targeting codelivery of CpG ODNs/PD-L1 peptide antagonists to enhance the immune checkpoint blockade-based anti-tumor effect

In order to reverse tumor immunosuppressive microenvironment and improve antitumor immune effect based on immune checkpoint blocking, a mannose-modified liposome-based CpG ODNs and PD-L1 antagonistic peptides (P) co-delivery system (HA/M-Lipo CpG-P) was constructed, in which hyaluronic acid (HA) coating was supposed to improve the systemic circulation stability and thereby promote its accumulation in tumor tissues. When the HA/M-Lipo CpG-P complexes enter the tumor tissues, HA will be hydrolyzed under the action of hyaluronidase, exposing P peptides. Then, P peptides linked by octapeptides that can be cleaved by matrix metalloproteinases (MMPs) are released into tumor tissues under the action of MMPs, exerting a blocking effect in the PD-1/PD-L1 pathway. The M-Lipo CpG complexes can recognize macrophage surface mannose receptors through its surface modified mannose molecules, and promote the intracellular delivery of CpG ODNs, thereby activating macrophages. The results showed that HA/M-Lipo CpG-P complexes successfully reversed M2-type macrophages in tumor microenvironment (TME) to M1, thereby activating anti-tumor related immune cells and inhibiting tumor growth. Moreover, the HA/M-Lipo CpG-P complexes showed a better tumor inhibitory effect than the HA/M-Lipo CpG or the HA/M-Lipo-P (monotherapy) treatment groups. Overall, HA/M-Lipo CpG-P complexes provide a promising co-delivery strategy for targeting tumors to improve the antitumor effect based on immune checkpoint blockade.

Immune profiling before treatment is predictive of TLR9-induced antitumor efficacy

TLR9 targeting has been a dynamic research field with promising potential in tumor immunotherapy. However, why most patients do not respond to TLR9 agonists remains unknown. In our attempt to resolve this issue, we observed that anti-tumor response to our TLR9-targeting cancer nanomedicines varied according to the initial immune profile of the animals. Speculating that immune profiling before treatment, including the measurement of IFN-α, IL-12, IL-6, TNF, tumor-infiltrating lymphocytes and spleen-residing lymphocytes, could be used to predictively distinguish responders from non-responders, we performed experiments in two different tumor models 4T1-BALB/c and B16-C57BL/6, to validate the hypothesis. Results confirmed that antitumor efficacy with respect to tumor growth, immune cell infiltration, and cytokines release, correlated with the different condition of individuals, as well as the categorization of the animals. This work suggests that immune profiling before treatment might be able to predict the antitumor efficacy of TLR9 agonists in vivo.

Nanomedicine-based immunotherapy for central nervous system disorders

Central nervous system (CNS) disorders represent a broad spectrum of brain ailments with short- and long-term disabilities, and nanomedicine-based approaches provide a new therapeutic approach to treating CNS disorders. A variety of potential drugs have been discovered to treat several neuronal disorders; however, their therapeutic success can be limited by the presence of the blood-brain barrier (BBB). Furthermore, unique immune functions within the CNS provide novel target mechanisms for the amelioration of CNS diseases. Recently, various therapeutic approaches have been applied to fight brain-related disorders, with moderate outcomes. Among the various therapeutic strategies, nanomedicine-based immunotherapeutic systems represent a new era that can deliver useful cargo with promising pharmacokinetics. These approaches exploit the molecular and cellular targeting of CNS disorders for enhanced safety, efficacy, and specificity. In this review, we focus on the efficacy of nanomedicines that utilize immunotherapy to combat CNS disorders. Furthermore, we detailed summarize nanomedicine-based pathways for CNS ailments that aim to deliver drugs across the BBB by mimicking innate immune actions.

A trustworthy CpG nanoplatform for highly safe and efficient cancer photothermal combined immunotherapy

Palladium nanosheets (Pd NSs) have recently attracted increasing research interest in the biomedical field due to their excellent near-infrared absorption, photothermal conversion capability and biocompatibility. However, the application of Pd NSs in immunotherapy has not been reported. Here, Pd NSs were used as the carriers of immunoadjuvant CpG ODNs for not only efficient delivery of CpG but also for enhancing the immunotherapeutic effects of CpG by the Pd NS-based photothermal therapy (PTT). Pd NSs had no influence on the immune system, and the prepared Pd-CpG nanocomposites, especially Pd(5)-CpG(PS), could significantly increase the uptake of CpG by immune cells and enhance the immunostimulatory activity of CpG in vitro and in vivo. With the combination of Pd(5)-CpG(PS) mediated PTT and immunotherapy, highly efficient tumor inhibition was achieved and the survival rate of the tumor-bearing mice was greatly increased depending on Pd(5)-CpG(PS) with safe near-infrared (NIR) irradiation (808 nm laser, 0.15 W cm^-2). Importantly, the combination therapy induced tumor cell death and released tumor-associated antigens, which could be effectively taken up and presented by antigen presenting cells with the assistance of CpG, leading to increased TNF-α and IL-6 production and enhanced cytotoxic T lymphocyte (CTL) activity. This work provides a new paradigm of utilizing photothermal nanomaterials for safe and highly efficient cancer photothermal combined immunotherapy.

High-Density Lipoprotein-Mimicking Nanodiscs for Chemo-immunotherapy against Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is an aggressive primary brain tumor, for which there is no cure. Treatment effectiveness for GBM has been limited due to tumor heterogeneity, an immunosuppressive tumor microenvironment (TME), and the presence of the blood-brain barrier, which hampers the transport of chemotherapeutic compounds to the central nervous system (CNS). High-density lipoprotein (HDL)-mimicking nanodiscs hold considerable promise to achieve delivery of bioactive compounds into tumors. Herein, we tested the ability of synthetic HDL nanodiscs to deliver chemotherapeutic agents to the GBM microenvironment and elicit tumor regression. To this end, we developed chemo-immunotherapy delivery vehicles based on sHDL nanodiscs loaded with CpG, a Toll-like receptor 9 (TLR9) agonist, together with docetaxel (DTX), a chemotherapeutic agent, for targeting GBM. Our data show that delivery of DTX-sHDL-CpG nanodiscs into the tumor mass elicited tumor regression and antitumor CD8+ T cell responses in the brain TME. We did not observe any overt off-target side effects. Furthermore, the combination of DTX-sHDL-CpG treatment with radiation (IR), which is the standard of care for GBM, resulted in tumor regression and long-term survival in 80% of GBM-bearing animals. Mice remained tumor-free upon tumor cell rechallenge in the contralateral hemisphere, indicating the development of anti-GBM immunological memory. Collectively, these data indicate that sHDL nanodiscs constitute an effective drug delivery platform for the treatment of GBM, resulting in tumor regression, long-term survival, and immunological memory when used in combination with IR. The proposed delivery platform has significant potential for clinical translation.

Improving Cancer Vaccine Efficiency by Nanomedicine

Cancer vaccines, which have been widely investigated in the past few decades, are one of the most attractive strategies for cancer immunotherapy. Through the precise delivery of antigens and adjuvants to lymphoid organs or lymphocytes via nanotechnology, innate and adaptive immunity can be boosted to prevent the growth and relapse of malignant tumors. Indeed, nanomedicine offers great opportunities to improve the efficiency of vaccines. Various functional platforms are used to deliver small molecules, peptides, nucleic acids, and even whole cell antigens to the target area of interest, achieving enhanced antitumor immunity and durable therapeutic benefits. Herein, the recent progress in cancer vaccines based on nanotechnology is summarized. Novel platforms used for delivering tumor antigens, promoting adjuvant functions, and combining other therapeutic strategies are discussed. Moreover, possible striving directions and major challenges of nanomedicine for vaccination are also reviewed.

Emerging blood–brain-barrier-crossing nanotechnology for brain cancer theranostics

The advancements, perspectives, and challenges in blood–brain-barrier (BBB)-crossing nanotechnology for effective brain tumor delivery and highly efficient brain cancer theranostics.

Gold nanoparticles-mediated photothermal therapy and immunotherapy

Cancer has been a significant threat to human health with more than eight million deaths each year in the world. Therefore, there is a significant need for novel technologies to effectively treat cancer and ultimately reduce cancer recurrences, treatment costs, number of radical cystectomies and mortality. A promising therapeutic platform for cancer is offered by nanoparticle-mediated therapy. This review highlights the development and applications of various nanoparticle platforms for photo-induced hyperthermia and immunotherapy. Taking advantage of gold's high biocompatibility, gold nanoparticles (GNPs) can be injected intravenously and accumulate preferentially in cancer cells due to the enhanced permeability and retention effect. Various gold nanoplatforms including nanospheres, nanoshells, nanorods, nanocages and nanostars have been used for effective photothermal treatment of various cancers. GNPs have also been used in immunotherapies, involving cancer antigen and immune adjuvant delivery as well as combination therapies with photothermal therapy. Among GNPs platforms, gold nanostars (GNS) have great therapeutic potential due to their unique star-shaped geometry that dramatically enhances light absorption and provides high photon-to-heat conversion efficiency due to the plasmonic effect. This photothermal process can be exploited to specifically ablate tumors and, more importantly, to amplify the antitumor immune response following the highly immunogenic thermal death of cancer cells. GNS-mediated photothermal therapy combined with checkpoint immunotherapy has been found to reverse tumor-mediated immunosuppression, thereby leading to the treatment of not only primary tumors but also cancer metastasis, as well as to induce effective long-lasting immunity, in other words, an anticancer ‘vaccine’ effect.

Metal-organic-framework-supported immunostimulatory oligonucleotides for enhanced immune response and imaging

We have demonstrated the ability of iron carboxylate metal-organic frameworks to efficiently deliver unmethylated cytosine-phosphate-guanine oligonucleotides. The nanoconjugates induced a stronger immune response than did free cytosine-phosphateguanine oligonucleotides and showed T₂-magnetic resonance imaging ability both in vitro and in vivo.

A bifunctional nanomodulator for boosting CpG-mediated cancer immunotherapy

Unmethylated cytosine-phosphate-guanine (CpG) oligonucleotides (ODNs) possess high immunostimulatory activity and represent attractive tools for cancer treatment. However, their success in eliminating large solid tumors was hampered by the immunosuppressive tumor microenvironment. Herein, we report that the design of a novel MnO₂-CpG-silver nanoclusters (AgNCs)-doxorubicin (DOX) conjugate for enhanced cancer immunotherapy, in which MnO₂ nanosheets function as unique supports to integrate the chemotherapy drug DOX and the immunotherapeutic agent CpG-AgNCs. Importantly, DOX could be conjugated with MnO₂ nanosheets through π-π interactions to serve as a bifunctional modulator of the tumor microenvironment to activate a tumor-specific immune response by inducing immunogenic cell death, and reverse the immunosuppressive tumor microenvironment via abrogating the immune-suppressive activity of regulatory T cells, both of which would greatly improve the immune response of CpG-AgNCs. In this way, the T-cell immune responses of CpG-AgNCs which are linked to MnO₂ nanosheets were significantly enhanced and could exhibit remarkable antitumor activity against large solid tumors. Our study may guide the rational design of immunotherapeutic boosters for improving cancer treatment.

CpG and transfer factor assembled on nanoparticles reduce tumor burden in mice glioma model

This work describes the use of a transfer factor, a low molecular protein that can transfer cell mediated immunity from donor to recipient, and CpG, a clinically relevant toll-like receptor agonist, for treating glioma.

Changes in apoptosis-related gene expression and cytokine release in breast cancer cells treated with CpG-loaded magnetic PAMAM nanoparticles

CpG-oligodeoxynucleotide (CpG-ODN) can function as an immune adjuvant. Previously, we showed that stimulation of breast cancer cells with CpG-ODN conjugated with PAMAM dendrimer-coated magnetic nanoparticles (DcMNPs) has induced apoptosis. The aim of the current study was to evaluate the expression levels of some apoptosis-regulating genes in several human breast cancer cells treated with CpG/DcMNPs. Treated MDA-MB231 cells showed an increase in Noxa and Bax gene expression levels, whereas the expression level of Survivin decreased. Similarly, Noxa gene was overexpressed in treated MCF7 cells. In treated SKBR3 cells, a decline in the c-Flip mRNA level was determined. Furthermore, release of cytokines, IL-6, IL-10, and TNF-α, was determined in cell culture supernatants. CpG/DcMNP treatment leads to an increase in the release of IL-6 in MDA-MB231 and SKBR3 cells, whereas release of IL-10 and TNF-α did not change significantly. It is indicated that CpG-ODN may show its cytotoxic effect by regulating the expression of apoptosis-related genes and the release of cytokine in breast cancer cells.

One-Shot Immunomodulatory Nanodiamond Agents for Cancer Immunotherapy

The use of functional nanodiamonds (fNDs) to deliver CpG oligonucleotides (ODNs) for sustained immunostimulation is reported. It is demonstrated that monotherapy using this immunostimulatory agent significantly suppresses the tumor growth in two murine tumor models. This fND-based nanoagent opens new opportunities for immunotherapy, as well as clinical applications of various types of therapeutic nucleic acids.

Metronomic Doses of Temozolomide Enhance the Efficacy of Carbon Nanotube CpG Immunotherapy in an Invasive Glioma Model

Even when treated with aggressive current therapies, most patients with glioblastoma survive less than two years. Rapid tumor growth, an invasive nature, and the blood-brain barrier, which limits the penetration of large molecules into the brain, all contribute to the poor tumor response associated with conventional therapies. Immunotherapy has emerged as a therapeutic approach that may overcome these challenges. We recently reported that single-walled carbon nanotubes (SWCNTs) can be used to dramatically increase the immunotherapeutic efficacy of CpG oligonucleotides in a mouse model of glioma. Following implantation in the mouse brain, the tumor cell line used in these previous studies (GL261) tends to form a spherical tumor with limited invasion into healthy brain. In order to evaluate SWCNT/CpG therapy under more clinically-relevant conditions, here we report the treatment of a more invasive mouse glioma model (K-Luc) that better recapitulates human disease. In addition, a CpG sequence previously tested in humans was used to formulate the SWCNT/CpG which was combined with temozolomide, the standard of care chemotherapy for glioblastoma patients. We found that, following two intracranial administrations, SWCNT/CpG is well-tolerated and improves the survival of mice bearing invasive gliomas. Interestingly, the efficacy of SWCNT/CpG was enhanced when combined with temozolomide. This enhanced anti-tumor efficacy was correlated to an increase of tumor-specific cytotoxic activity in splenocytes. These results reinforce the emerging understanding that immunotherapy can be enhanced by combining it with chemotherapy and support the continued development of SWCNT/CpG.

Additive antitumour response to the rabbit VX2 hepatoma by combined radio frequency ablation and toll like receptor 9 stimulation

INTRODUCTION

Radiofrequency ablation (RFA), a palliative therapeutic option for solid hepatic tumours, stimulates localised and systemic antitumour cytotoxic T cells. We studied how far addition of CpG B oligonucleotides, toll like receptor (TLR) 9 agonists, would increase the antitumoural T cell response of RFA in the highly aggressive VX2 hepatoma.

METHODS

Rabbits were randomised to receive RFA, CpG B, their combination or no therapy. The antitumour efficacy of RFA alone or in combination with CpG B was further tested by rechallenging a separate group with intravenously injected VX2 tumour cells after 120 days. Animals were assessed for survival, tumour size and spread, and tumour and immune related histological markers after 120 days. Peripheral blood mononuclear cells were tested for tumour-specific T cell activation and cytotoxicity. Immune modulatory cytokines tumour necrosis factor α, interleukin (IL)-2/IL-8/IL-10/IL-12 and interferon γ, and vascular endothelial growth factor were measured in serum.

RESULTS

Mean survival of untreated animals was 36 days, as compared with 97, 78 and 114 days for RFA, CpG and combination therapy, respectively. Compared with untreated controls, antitumour T cell stimulation/cytotoxicity increased 26/16-fold, 32/17-fold and 50/38-fold 2 weeks after RFA, CpG and combination treatments, respectively. The combination inhibited tumour spread to lungs and peritoneum significantly and prohibited new tumour growth in animals receiving a secondary systemic tumour cell injection. RFA alone induced a Th1 cytokine pattern, while IL-8 and IL-10 were only upregulated in CpG treated animals and controls.

CONCLUSIONS

The combination of TLR9 stimulation with RFA resulted in a potentiated antitumour T cell response and cytotoxicity in the VX2 tumour model. Only this combination prevented subsequent tumour spread and resulted in a significantly improved survival, justifying the need for further exploration of the combination of ablative therapies and TLR9 agonists in liver cancer.

Development of multifunctional lipid nanocapsules for the co-delivery of paclitaxel and CpG-ODN in the treatment of glioblastoma

In this work, multifunctional lipid nanocapsules (M-LNC) were designed to combine the activity of the cytotoxic drug paclitaxel (PTX) with the immunostimulant CpG. This nanosystem, consisting of modified lipid nanocapsules coated with a cationic polymeric shell composed of chitosan (CS), was able to allocate the hydrophobic drug PTX in the inner oily core, and to associate onto the surface the genetic material CpG. The CS-coated LNC (CS-LNC), showed a narrow size distribution with an average size of 70 nm and a positive zeta potential (+25 mV). They encapsulated PTX in a high amount (98%), and, due to the cationic surface charge, were able to adsorb CpG without losing stability. As a preliminary in vitro study, the apoptotic effect on GL261 glioma cells was investigated. The drug-loaded CS-LNC exhibited the ability to interact with glioma cells and induce an important apoptotic effect in comparison with blank systems. Finally, the M-LNC made of CS-LNC loaded with both CpG and PTX were tested in vivo, injected via convention enhanced delivery (CED) in GL261-glioma-bearing mice. The results showed that the overall survival of mice treated with the M-LNC was significantly increased in comparison with the control, Taxol(®), or the separated injection of PTX-loaded LNC and CpG. This effect was also confirmed by magnetic resonance imaging (MRI) which revealed the reduction of tumor growth in the animals treated with CpG and PTX-loaded M-LNC. All these findings suggested that the developed M-LNC could potentiate both CpG immunopotency and PTX antitumor activity by enhancing its delivery into the tumor microenvironment.

Functionalized iron oxide nanoparticles for controlling the movement of immune cells

Immunotherapy is currently being investigated for the treatment of many diseases, including cancer. The ability to control the location of immune cells during or following activation would represent a powerful new technique for this field. Targeted magnetic delivery is emerging as a technique for controlling cell movement and localization. Here we show that this technique can be extended to microglia, the primary phagocytic immune cells in the central nervous system. The magnetized microglia were generated by loading the cells with iron oxide nanoparticles functionalized with CpG oligonucleotides, serving as a proof of principle that nanoparticles can be used to both deliver an immunostimulatory cargo to cells and to control the movement of the cells. The nanoparticle-oligonucleotide conjugates are efficiently internalized, non-toxic, and immunostimulatory. We demonstrate that the in vitro migration of the adherent, loaded microglia can be controlled by an external magnetic field and that magnetically-induced migration is non-cytotoxic. In order to capture video of this magnetically-induced migration of loaded cells, a novel 3D-printed "cell box" was designed to facilitate our imaging application. Analysis of cell movement velocities clearly demonstrate increased cell velocities toward the magnet. These studies represent the initial step towards our final goal of using nanoparticles to both activate immune cells and to control their trafficking within the diseased brain.

Impaired interferon-alpha production by plasmacytoid dendritic cells after cord blood transplantation in children: implication for post-transplantation toll-like receptor ligand-based immunotherapy

Plasmacytoid dendritic cells (pDCs) initiate both innate and adaptive immune responses, making them attractive targets for post-transplantation immunotherapy, particularly after cord blood transplantation (CBT). Toll-like receptor (TLR) agonists are currently studied for pDC stimulation in various clinical settings. Their efficacy depends on pDC number and functionality, which are unknown after CBT. We performed a longitudinal study of pDC reconstitution in children who underwent bone marrow transplantation (BMT) and single-unit CBT. Both CBT and unrelated BMT patients received antithymocyte globulin as part of their graft-versus-host disease prophylaxis regimen. pDC blood counts were higher in CBT patients than in healthy volunteers from 2 to 9 months after transplantation, whereas they remained lower in BMT patients. We showed that cord blood progenitors gave rise in vitro to a 500-fold increase in functional pDCs over bone marrow counterparts. Upon stimulation with a TLR agonist, pDCs from both CBT and BMT recipients upregulated T cell costimulatory molecules, whereas interferon-alpha (IFN-α) production was impaired for 9 months after CBT. TLR agonist treatment is thus not expected to induce IFN-α production by pDCs after CBT, limiting its immunotherapeutic potential. Fortunately, in vitro production of large amounts of functional pDCs from cord blood progenitors paves the way for the post-transplantation adoptive transfer of pDCs.

Toll-like receptor agonists: current status and future perspective on their utility as adjuvants in improving anticancer vaccination strategies

Toll-like receptor (TLR) agonists possess remarkable properties, particularly with regard to dendritic cell activation, promoting Th1-type cytokine production and optimizing cytotoxic T-cell responses. Preclinical and clinical studies conducted to date show that TLR agonists can improve currently applied anticancer vaccination protocols. Although these have resulted in the US FDA approval of three TLR agonists for use in humans, their abundant application encounters limitations, principally due to dose-limiting toxicity evoking from systemic cytokine production. Here, using selected examples of clinical studies, we provide a concise review regarding the knowledge acquired thus far on the adjuvant use of TLR agonists as cancer vaccine components. We also provide evidence on the exploitation of a novel TLR agonist, prothymosin-α, which enhances the efficacy of tumor-reactive effectors without causing severe adverse effects.

Gold nanoparticle mediated cancer immunotherapy

Significant progress has been made in the field of cancer immunotherapy, where the goal is to activate or modulate the body's immune response against cancer. However, current immunotherapy approaches exhibit limitations of safety and efficacy due to systemic delivery. In this context, the use of nanotechnology for the delivery of cancer vaccines and immune adjuvants presents a number of advantages such as targeted delivery to immune cells, enhanced therapeutic effect, and reduced adverse outcomes. Recently, gold nanoparticles (AuNP) have been explored as immunotherapy carriers, creating new AuNP applications that merit a critical overview. This review highlights recent advances in the development of AuNP mediated immunotherapies that harness AuNP biodistribution, optical properties and their ability to deliver macromolecules such as peptides and oligonucleotides. It has been demonstrated that the use of AuNP carriers can improve the delivery and safety of immunotherapy agents, and that AuNP immunotherapies are well suited for synergistic combination therapy with existing cancer therapies like photothermal ablation.

FROM THE CLINICAL EDITOR

Cancer immunotherapy approaches are rapidly evolving and are some of the most promising avenues to approach malignancies. This review summarizes the role of gold nanoparticles in immunotherapy agent delivery, and in the development of synergistic therapies such as photothermal ablation.