Current State of Dendritic Cell-Based Immunotherapy: Opportunities for in vitro Antigen Loading of Different DC Subsets?

Type I conventional dendritic cells facilitate immunotherapy in pancreatic cancer

Inflammation and tissue damage associated with pancreatitis can precede or occur concurrently with pancreatic ductal adenocarcinoma (PDAC). We demonstrate that in PDAC coupled with pancreatitis (ptPDAC), antigen-presenting type I conventional dendritic cells (cDC1s) are specifically activated. Immune checkpoint blockade therapy (iCBT) leads to cytotoxic CD8+ T cell activation and elimination of ptPDAC with restoration of life span even upon PDAC rechallenge. Using PDAC antigen-loaded cDC1s as a vaccine, immunotherapy-resistant PDAC was rendered sensitive to iCBT with elimination of tumors. cDC1 vaccination coupled with iCBT identified specific CDR3 sequences in the tumor-infiltrating CD8+ T cells with potential therapeutic importance. This study identifies a fundamental difference in the immune microenvironment in PDAC concurrent with, or without, pancreatitis and provides a rationale for combining cDC1 vaccination with iCBT as a potential treatment option.

Lung cancer vaccination from concept to reality: A critical review of clinical trials and latest advances

Lung cancer is a highly lethal malignancy that poses a significant burden on public health worldwide. There have been numerous therapeutic approaches, among which cancer vaccines have emerged as a promising approach to harnessing the patient's immune system to induce long-lasting anti-tumor immunity. The current study aims to provide an overview of cancer vaccination in the context of lung cancer to establish a clearer landscape for lung cancer treatment. To provide a comprehensive review, we not only gathered the published studies of lung cancer vaccination and discussed their effectiveness and safety profile but also analyzed all the relevant clinical trials registered on www.clinicaltrials.gov until March 2024. We demonstrated all utilized vaccine platforms along with having a glance at novel technologies such as mRNA vaccines. The present review discussed the challenges and shortcomings of lung cancer vaccination, as well as the way they could be managed to pave the way for reaching the most optimized vaccine formulation.

Advances and prospects of mRNA vaccines in cancer immunotherapy

Cancer vaccines, designed to activate the body's own immune system to fight against tumors, are a current trend in cancer treatment and receiving increasing attention. Cancer vaccines mainly include oncolytic virus vaccine, cell vaccine, peptide vaccine and nucleic acid vaccine. Over the course of decades of research, oncolytic virus vaccine T-VEC, cellular vaccine sipuleucel-T, various peptide vaccines, and DNA vaccine against HPV positive cervical cancer have brought encouraging results for cancer therapy, but are losing momentum in development due to their respective shortcomings. In contrast, the advantages of mRNA vaccines such as high safety, ease of production, and unmatched efficacy are on full display. In addition, advances in technology such as pseudouridine modification have cracked down the bottleneck for developing mRNA vaccines including instability, innate immunogenicity, and low efficiency of in vivo delivery. Several cancer mRNA vaccines have achieved promising results in clinical trials, and their usage in conjunction with other immune checkpoint inhibitors (ICIs) has further boosted the efficiency of anti-tumor immune response. We expect a rapid development of mRNA vaccines for cancer immunotherapy in the near future. This review provides a brief overview of the current status of mRNA vaccines, highlights the action mechanism of cancer mRNA vaccines, their recent advances in clinical trials, and prospects for their clinical applications.

Current Technologies and Future Perspectives in Immunotherapy towards a Clinical Oncology Approach

Immunotherapy is now established as a potent therapeutic paradigm engendering antitumor immune response against a wide range of malignancies and other diseases by modulating the immune system either through the stimulation or suppression of immune components such as CD4+ T cells, CD8+ T cells, B cells, monocytes, macrophages, dendritic cells, and natural killer cells. By targeting several immune checkpoint inhibitors or blockers (e.g., PD-1, PD-L1, PD-L2, CTLA-4, LAG3, and TIM-3) expressed on the surface of immune cells, several monoclonal antibodies and polyclonal antibodies have been developed and already translated clinically. In addition, natural killer cell-based, dendritic cell-based, and CAR T cell therapies have been also shown to be promising and effective immunotherapeutic approaches. In particular, CAR T cell therapy has benefited from advancements in CRISPR-Cas9 genome editing technology, allowing the generation of several modified CAR T cells with enhanced antitumor immunity. However, the emerging SARS-CoV-2 infection could hijack a patient's immune system by releasing pro-inflammatory interleukins and cytokines such as IL-1β, IL-2, IL-6, and IL-10, and IFN-γ and TNF-α, respectively, which can further promote neutrophil extravasation and the vasodilation of blood vessels. Despite the significant development of advanced immunotherapeutic technologies, after a certain period of treatment, cancer relapses due to the development of resistance to immunotherapy. Resistance may be primary (where tumor cells do not respond to the treatment), or secondary or acquired immune resistance (where tumor cells develop resistance gradually to ICIs therapy). In this context, this review aims to address the existing immunotherapeutic technologies against cancer and the resistance mechanisms against immunotherapeutic drugs, and explain the impact of COVID-19 on cancer treatment. In addition, we will discuss what will be the future implementation of these strategies against cancer drug resistance. Finally, we will emphasize the practical steps to lay the groundwork for enlightened policy for intervention and resource allocation to care for cancer patients.

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

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

Fluid shear stress enhances dendritic cell activation

Ex vivo activation of dendritic cells (DCs) has been widely explored for targeted therapies, although these treatments remain expensive. Reducing treatment costs while enhancing cell activation could help to make immunotherapies more accessible. Cells can be activated by both internal and external forces including fluid shear stress (FSS). FSS activates cells via opening of mechanosensitive ion channels. In this study, dendritic cells were activated by sustained exposure to circulatory levels of fluid shear stress using a cone-and-plate flow device and analyzed for activation markers. After 1 h of shear stress exposure, an increase in cytokine release was present in immortalized cells as well as phosphorylation of the proteins NF-κB and cFos in primary DCs. Changes in DC morphology, metabolism and proliferation were also observed. These compelling new findings point to the potential for using FSS to activate DCs for ex vivo therapeutics.

Dendritic Cell Vaccines Impact the Type 2 Innate Lymphoid Cell Population and Their Cytokine Generation in Mice

Dendritic cell (DC) vaccines can stimulate the immune system to target cancer antigens, making them a promising therapy in immunotherapy. Clinical trials have shown limited effectiveness of DC vaccines, highlighting the need to enhance the immune responses they generate. Innate lymphoid cells (ILCs) are a diverse group of innate leukocytes that produce various cytokines and regulate the immune system. These cells have the potential to improve immunotherapies. There is not much research on how group 2 ILCs (ILC2s) communicate with DC vaccines. Therefore, examining the roles of DC vaccination in immune responses is crucial. Our research analyzed the effects of DC vaccination on the ILC2 populations and their cytokine production. By exploring the relationship between ILC2s and DCs, we aimed to understand how this could affect DC-based immunotherapies. The results showed an increase in the number of ILC2s in the local draining lymph node and spleen of tumor-free mice, as well as in the lungs of mice challenged with tumors in a pulmonary metastasis model. This suggests a complex interplay between DC-based vaccines and ILC2s, which is further influenced by the presence of tumors.

Adjuvant dendritic cell-based immunotherapy after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in patients with malignant peritoneal mesothelioma: a phase II clinical trial

BACKGROUND

Malignant peritoneal mesothelioma (MPM) is an aggressive malignancy with a poor prognosis. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) improves survival outcomes, but recurrence rates remain high. Dendritic cell-based immunotherapy (DCBI) showed promising results in patients with pleural mesothelioma. The primary aim of this trial was to determine feasibility of adjuvant DCBI after CRS-HIPEC.

METHODS

This open-label, single-center, phase II clinical trial, performed in the Erasmus MC Cancer Institute Rotterdam, the Netherlands, included patients with epithelioid MPM. 4-6 weeks before CRS-HIPEC leukapheresis was performed. 8-10 weeks after surgery, DCBI was administered three times biweekly. Feasibility was defined as administration of at least three adjuvant vaccinations in 75% of patients. Comprehensive immune cell profiling was performed on peripheral blood samples prior to and during treatment.

RESULTS

All patients who received CRS-HIPEC (n=16) were successfully treated with adjuvant DCBI. No severe toxicity related to DCBI was observed. Median progression-free survival (PFS) was 12 months (IQR 5-23) and median overall survival was not reached. DCBI was associated with increased proliferation of circulating natural killer cells and CD4+ T-helper (Th) cells. Co-stimulatory molecules, including ICOS, HLA-DR, and CD28 were upregulated predominantly on memory or proliferating Th-cells and minimally on CD8+ cytotoxic T-lymphocytes (CTLs) after treatment. However, an increase in CD8+ terminally differentiated effector memory (Temra) cells positively correlated with PFS, whereas co-expression of ICOS and Ki67 on CTLs trended towards a positive correlation.

CONCLUSIONS

Adjuvant DCBI after CRS-HIPEC in patients with MPM was feasible and safe, and showed promising survival outcomes. DCBI had an immune modulatory effect on lymphoid cells and induced memory T-cell activation. Moreover, an increase of CD8+ Temra cells was more pronounced in patients with longer PFS. These data provide rationale for future combination treatment strategies.

TRIAL REGISTRATION NUMBER

NTR7060; Dutch Trial Register (NTR).

Current insights into the hepatic microenvironment and advances in immunotherapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and shows high global incidence and mortality rates. The liver is an immune-tolerated organ with a specific immune microenvironment that causes traditional therapeutic approaches to HCC, such as chemotherapy, radiotherapy, and molecular targeted therapy, to have limited efficacy. The dramatic advances in immuno-oncology in the past few decades have modified the paradigm of cancer therapy, ushering in the era of immunotherapy. Currently, despite the rapid integration of cancer immunotherapy into clinical practice, some patients still show no response to treatment. Therefore, a rational approach is to target the tumor microenvironment when developing the next generation of immunotherapy. This review aims to provide insights into the hepatic immune microenvironment in HCC and summarize the mechanisms of action and clinical usage of immunotherapeutic options for HCC, including immune checkpoint blockade, adoptive therapy, cytokine therapy, vaccine therapy, and oncolytic virus-based therapy.

Enhanced in vivo anti-tumor efficacy of whole tumor lysate in combination with whole tumor cell-specific polyclonal antibody

Background and purpose

Despite the widespread utilization of cancer vaccines with specified antigens, the use of whole tumor cell lysates in tumor immunotherapy would be a very promising approach that can overcome several significant obstacles in vaccine production. Whole tumor cells provide a broad source of tumor-associated antigens and can activate cytotoxic T lymphocytes and CD4+ T helper cells concurrently. On the other hand, as an effective immunotherapy strategy, recent investigations have shown that the multi-targeting of tumor cells with polyclonal antibodies, which are also more effective than monoclonal antibodies at mediating effector functions for target elimination, might minimize the escape variants.

Experimental approach

We prepared polyclonal antibodies by immunizing rabbits with the highly invasive 4T1 breast cancer cell line.

Findings/Results

In vitro investigation indicated that the immunized rabbit serum inhibited cell proliferation and induced apoptosis in target tumor cells. Moreover, in vivo analysis showed enhanced anti-tumor efficacy of whole tumor cell lysate in combination with tumor cell-immunized serum. This combination therapy proved beneficial in significant inhibition of the tumor growth and the established tumor was entirely eradicated in treated mice.

Conclusion and implications

Serial intravenous injections of tumor cell immunized rabbit serum significantly inhibited tumor cell proliferation and induced apoptosis in vitro and in vivo in combination with whole tumor lysate. This platform could be a promising method for developing clinical-grade vaccines and open up the possibility of addressing the effectiveness and safety of cancer vaccines.

Antigen-presenting type-I conventional dendritic cells facilitate curative checkpoint blockade immunotherapy in pancreatic cancer

Inflammation and tissue damage associated with pancreatitis can precede or occur concurrently with pancreatic ductal adenocarcinoma (PDAC). We demonstrate that in PDAC coupled with pancreatitis (ptPDAC), antigen-presenting type-I conventional dendritic cells (cDC1s) are specifically activated. Immune checkpoint blockade therapy (iCBT) leads to cytotoxic CD8 + T cell activation and eradication of ptPDAC with restoration of lifespan even upon PDAC re-challenge. Such eradication of ptPDAC was reversed following specific depletion of dendritic cells. Employing PDAC antigen-loaded cDC1s as a vaccine, immunotherapy-resistant PDAC was rendered sensitive to iCBT with a curative outcome. Analysis of the T-cell receptor (TCR) sequences in the tumor infiltrating CD8 + T cells following cDC1 vaccination coupled with iCBT identified unique CDR3 sequences with potential therapeutic significance. Our findings identify a fundamental difference in the immune microenvironment and adaptive immune response in PDAC concurrent with, or without pancreatitis, and provides a rationale for combining cDC1 vaccination with iCBT as a potential treatment option.

A Comprehensive View of the Cancer-Immunity Cycle (CIC) in HPV-Mediated Cervical Cancer and Prospects for Emerging Therapeutic Opportunities

Cervical cancer (CC) is the fourth most common cancer in women worldwide, with more than 500,000 new cases each year and a mortality rate of around 55%. Over 80% of these deaths occur in developing countries. The most important risk factor for CC is persistent infection by a sexually transmitted virus, the human papillomavirus (HPV). Conventional treatments to eradicate this type of cancer are accompanied by high rates of resistance and a large number of side effects. Hence, it is crucial to devise novel effective therapeutic strategies. In recent years, an increasing number of studies have aimed to develop immunotherapeutic methods for treating cancer. However, these strategies have not proven to be effective enough to combat CC. This means there is a need to investigate immune molecular targets. An adaptive immune response against cancer has been described in seven key stages or steps defined as the cancer-immunity cycle (CIC). The CIC begins with the release of antigens by tumor cells and ends with their destruction by cytotoxic T-cells. In this paper, we discuss several molecular alterations found in each stage of the CIC of CC. In addition, we analyze the evidence discovered, the molecular mechanisms and their relationship with variables such as histological subtype and HPV infection, as well as their potential impact for adopting novel immunotherapeutic approaches.

Neutrophils in Dendritic Cell-Based Cancer Vaccination: The Potential Roles of Neutrophil Extracellular Trap Formation

Neutrophils have conflicting roles in the context of cancers, where they have been associated with contributing to both anti-tumor and pro-tumor responses. Their functional heterogenicity is plastic and can be manipulated by environmental stimuli, which has fueled an area of research investigating therapeutic strategies targeting neutrophils. Dendritic cell (DC)-based cancer vaccination is an immunotherapy that has exhibited clinical promise but has shown limited clinical efficacy. Enhancing our understanding of the communications occurring during DC cancer vaccination can uncover opportunities for enhancing the DC vaccine platform. There have been observed communications between neutrophils and DCs during natural immune responses. However, their crosstalk has been poorly studied in the context of DC vaccination. Here, we review the dual functionality of neutrophils in the context of cancers, describe the crosstalk between neutrophils and DCs during immune responses, and discuss their implications in DC cancer vaccination. This discussion will focus on how neutrophil extracellular traps can influence immune responses in the tumor microenvironment and what roles they may play in promoting or hindering DC vaccine-induced anti-tumor efficacy.

LL-37 as a Powerful Molecular Tool for Boosting the Performance of Ex Vivo-Produced Human Dendritic Cells for Cancer Immunotherapy

Ex vivo-produced dendritic cells (DCs) constitute the core of active cellular immunotherapy (ACI) for cancer treatment. After many disappointments in clinical trials, the current protocols for their preparation are attempting to boost their therapeutic efficacy by enhancing their functionality towards Th1 response and capability to induce the expansion of cytotoxic tumor-specific CD8⁺ T cells. LL-37 is an antimicrobial peptide with strong immunomodulatory potential. This potential was previously found to either enhance or suppress the desired anti-tumor DC functionality when used at different phases of their ex vivo production. In this work, we show that LL-37 can be implemented during the whole process of DC production in a way that allows LL-37 to enhance the anti-tumor functionality of produced DCs. We found that the supplementation of LL-37 during the differentiation of monocyte-derived DCs showed only a tendency to enhance their in vitro-induced lymphocyte enrichment with CD8⁺ T cells. The supplementation of LL-37 also during the process of DC antigen loading (pulsation) and maturation significantly enhanced the cell culture enrichment with CD8⁺ T cells. Moreover, this enrichment was also associated with the downregulated expression of PD-1 in CD8⁺ T cells, significantly higher frequency of tumor cell-reactive CD8⁺ T cells, and superior in vitro cytotoxicity against tumor cells. These data showed that LL-37 implementation into the whole process of the ex vivo production of DCs could significantly boost their anti-tumor performance in ACI.

Dendritic Cell-Based Vaccines Against Cancer: Challenges, Advances and Future Opportunities

As the most potent professional antigen presenting cells, dendritic cells (DCs) have the ability to activate both naive CD4 and CD8 T cells. Recognized for their exceptional ability to cross-present exogenous antigens to prime naive antigen-specific CD8 T cells, DCs play a critical role in generating CD8 T cell immunity, as well as mediating CD8 T cell tolerance to tumor antigens. Despite the ability to potentiate host CD8 T cell-mediated anti-tumor immunity, current DC-based cancer vaccines have not yet achieved the promised success clinically with the exception of FDA-approved Provenge. Interestingly, recent studies have shown that type 1 conventional DCs (cDC1s) play a critical role in cross-priming tumor-specific CD8 T cells and determining the anti-tumor efficacy of cancer immunotherapies including immune checkpoint blockade (ICB). Together with promising clinical results in neoantigen-based cancer vaccines, there is a great need for DC-based vaccines to be further developed and refined either as monotherapies or in combination with other immunotherapies. In this review, we will present a brief review of DC development and function, discuss recent progress, and provide a perspective on future directions to realize the promising potential of DC-based cancer vaccines.

Immunotherapy approaches for hematological cancers

Hematological cancers such as leukemia, lymphoma, and multiple myeloma have traditionally been treated with chemo and radiotherapy approaches. Introduction of immunotherapies for treatment of these diseases has led to patient remissions that would not have been possible with traditional approaches. In this critical review we identify main disease characteristics, symptoms, and current treatment options. Five common immunotherapies, namely checkpoint inhibitors, vaccines, cell-based therapies, antibodies, and oncolytic viruses, are described, and their applications in hematological cancers are critically discussed.

GP, Gopalakrishnan AV. Role of Immune Cells and Receptors in Cancer Treatment: An Immunotherapeutic Approach

Cancer immunotherapy moderates the immune system’s ability to fight cancer. Due to its extreme complexity, scientists are working to put together all the puzzle pieces to get a clearer picture of the immune system. Shreds of available evidence show the connection between cancer and the immune system. Immune responses to tumors and lymphoid malignancies are influenced by B cells, γδT cells, NK cells, and dendritic cells (DCs). Cancer immunotherapy, which encompasses adoptive cancer therapy, monoclonal antibodies (mAbs), immune checkpoint therapy, and CART cells, has revolutionized contemporary cancer treatment. This article reviews recent developments in immune cell regulation and cancer immunotherapy. Various options are available to treat many diseases, particularly cancer, due to the progress in various immunotherapies, such as monoclonal antibodies, recombinant proteins, vaccinations (both preventative and curative), cellular immunotherapies, and cytokines.

Nanoscale organization of the MHC I peptide-loading complex in human dendritic cells

Dendritic cells (DCs) translate local innate immune responses into long-lasting adaptive immunity by priming antigen-specific T cells. Accordingly, there is an ample interest in exploiting DCs for therapeutic purposes, e.g., in personalized immunotherapies. Despite recent advances in elucidating molecular pathways of antigen processing, in DCs the exact spatial organization of the underlying processes is largely unknown. Here, we unraveled the nanoscale organization of the transporter associated with antigen processing (TAP)-dependent peptide-loading machinery in human monocyte-derived DCs (moDC). We detected an unexpected accumulation of MHC I peptide-loading complexes (PLCs) and TAP-dependent peptide compartmentalization in protrusions of activated DCs. Using single-molecule localization microscopy we revealed that PLCs display homogeneously sized assemblies, independent of the DC activation status or cellular localization. Our data indicate that moDCs show augmentation of subcellular PLC density during DC maturation. We observed a twofold density increase in the cell body, while an even fourfold accumulation was detected in the tips of the protrusions at the mature DC stage in comparison to immature DCs. In these tip regions, PLC assemblies are found along highly compressed tubular ER networks. These findings provide novel insights into nanoscale organization of the antigen presentation machinery, and open new perspectives on the T cell stimulatory capacity of DCs.

Human Variation in DNA Repair, Immune Function, and Cancer Risk

DNA damage constantly threatens genome integrity, and DNA repair deficiency is associated with increased cancer risk. An intuitive and widely accepted explanation for this relationship is that unrepaired DNA damage leads to carcinogenesis due to the accumulation of mutations in somatic cells. But DNA repair also plays key roles in the function of immune cells, and immunodeficiency is an important risk factor for many cancers. Thus, it is possible that emerging links between inter-individual variation in DNA repair capacity and cancer risk are driven, at least in part, by variation in immune function, but this idea is underexplored. In this review we present an overview of the current understanding of the links between cancer risk and both inter-individual variation in DNA repair capacity and inter-individual variation in immune function. We discuss factors that play a role in both types of variability, including age, lifestyle, and environmental exposures. In conclusion, we propose a research paradigm that incorporates functional studies of both genome integrity and the immune system to predict cancer risk and lay the groundwork for personalized prevention.

Trial watch: Dendritic cell (DC)-based immunotherapy for cancer

Dendritic cell (DC)-based vaccination for cancer treatment has seen considerable development over recent decades. However, this field is currently in a state of flux toward niche-applications, owing to recent paradigm-shifts in immuno-oncology mobilized by T cell-targeting immunotherapies. DC vaccines are typically generated using autologous (patient-derived) DCs exposed to tumor-associated or -specific antigens (TAAs or TSAs), in the presence of immunostimulatory molecules to induce DC maturation, followed by reinfusion into patients. Accordingly, DC vaccines can induce TAA/TSA-specific CD8⁺/CD4⁺ T cell responses. Yet, DC vaccination still shows suboptimal anti-tumor efficacy in the clinic. Extensive efforts are ongoing to improve the immunogenicity and efficacy of DC vaccines, often by employing combinatorial chemo-immunotherapy regimens. In this Trial Watch, we summarize the recent preclinical and clinical developments in this field and discuss the ongoing trends and future perspectives of DC-based immunotherapy for oncological indications.

Dendritic cell transfer for cancer immunotherapy

Dendritic cells (DCs) play a major role in cancer immunosurveillance as they bridge innate and adaptive immunity by detecting tumor-associated antigens and presenting them to T lymphocytes. The adoptive transfer of antigen loaded DCs has been proposed as an immunotherapeutic approach for the treatment of various types of cancer. Nevertheless, despite promising preclinical data, the therapeutic efficacy of DC transfer is still deceptive in cancer patients. Here we summarize recent findings in DC biology with a special focus on the development of actionable therapeutic strategies and discuss experimental and clinical approaches that aim at improving the efficacy of DC-based immunotherapies, including, but not limited to, optimized DC production and antigen loading, stimulated maturation, the co-treatment with additional immunotherapies, as well as the inhibition of DC checkpoints.

Dendritic cells metabolism: a strategic path to improve antitumoral DC vaccination

The critical role developed by dendritic cell (DC) in the orchestration of immune response explains its exploitation in different therapeutic approaches as potential vaccine tools. Various clinical trials dissect its role in different types of solid cancers. However, there is a lack of comprehension regarding the potential impact of DC metabolic pathways on the effectiveness of DC vaccine. In this review, we intend to dissect how metabolism could be a critical component of DC vaccine formulation, exploring opportunities to improve: (i) processing and cross-presentation of tumour antigens; (ii) DC migration, and (iii) DC immunogenic profile. Overall, we aim to open the discussion to explore new avenues/paths where DC metabolism might be considered a core component of antitumour DC vaccine with this review.

Human Tumor Targeted Cytotoxic Mast Cells for Cancer Immunotherapy

The diversity of autologous cells being used and investigated for cancer therapy continues to increase. Mast cells (MCs) are tissue cells that contain a unique set of anti-cancer mediators and are found in and around tumors. We sought to exploit the anti-tumor mediators in MC granules to selectively target them to tumor cells using tumor specific immunoglobin E (IgE) and controllably trigger release of anti-tumor mediators upon tumor cell engagement. We used a human HER2/neu-specific IgE to arm human MCs through the high affinity IgE receptor (FcεRI). The ability of MCs to bind to and induce apoptosis of HER2/neu-positive cancer cells in vitro and in vivo was assessed. The interactions between MCs and cancer cells were investigated in real time using confocal microscopy. The mechanism of action using cytotoxic MCs was examined using gene array profiling. Genetically manipulating autologous MC to assess the effects of MC-specific mediators have on apoptosis of tumor cells was developed using siRNA. We found that HER2/neu tumor-specific IgE-sensitized MCs bound, penetrated, and killed HER2/neu-positive tumor masses in vitro. Tunneling nanotubes formed between MCs and tumor cells are described that parallel tumor cell apoptosis. In solid tumor, human breast cancer (BC) xenograft mouse models, infusion of HER2/neu IgE-sensitized human MCs co-localized to BC cells, decreased tumor burden, and prolonged overall survival without indications of toxicity. Gene microarray of tumor cells suggests a dependence on TNF and TGFβ signaling pathways leading to apoptosis. Knocking down MC-released tryptase did not affect apoptosis of cancer cells. These studies suggest MCs can be polarized from Type I hypersensitivity-mediating cells to cytotoxic cells that selectively target tumor cells and specifically triggered to release anti-tumor mediators. A strategy to investigate which MC mediators are responsible for the observed tumor killing is described so that rational decisions can be made in the future when selecting which mediators to target for deletion or those that could further polarize them to cytotoxic MC by adding other known anti-tumor agents. Using autologous human MC may provide further options for cancer therapeutics that offers a unique anti-cancer mechanism of action using tumor targeted IgE’s.

The Role of Type-2 Conventional Dendritic Cells in the Regulation of Tumor Immunity

Simple Summary

Recent studies revealed that type-2 conventional dendritic cells (cDC2s) play an important role in antitumor immunity by promoting cytotoxic T-cell responses and helper T-cell differentiation. This review outlines the role of cDC2s in tumor immunity and summarizes the latest progress regarding their potential in cancer vaccination and cDC2-targeted cancer immunotherapy.

Abstract

Conventional dendritic cells (cDCs) orchestrate immune responses to cancer and comprise two major subsets: type-1 cDCs (cDC1s) and type-2 cDCs (cDC2s). Compared with cDC1s, which are dedicated to the activation of CD8⁺ T cells, cDC2s are ontogenically and functionally heterogeneous, with their main function being the presentation of exogenous antigens to CD4⁺ T cells for the initiation of T helper cell differentiation. cDC1s play an important role in tumor-specific immune responses through cross-presentation of tumor-derived antigens for the priming of CD8⁺ T cells, whereas little is known of the role of cDC2s in tumor immunity. Recent studies have indicated that human cDC2s can be divided into at least two subsets and have implicated these cells in both anti- and pro-tumoral immune responses. Furthermore, the efficacy of cDC2-based vaccines as well as cDC2-targeted therapeutics has been demonstrated in both mouse models and human patients. Here we summarize current knowledge about the role of cDC2s in tumor immunity and address whether these cells are beneficial in the context of antitumor immune responses.

Harnessing the Anti-Tumor Mediators in Mast Cells as a New Strategy for Adoptive Cell Transfer for Cancer

The emergence of cancer immunotherapies utilizing adoptive cell transfer (ACT) continues to be one of the most promising strategies for cancer treatment. Mast cells (MCs) which occur throughout vascularized tissues, are most commonly associated with Type I hypersensitivity, bind immunoglobin E (IgE) with high affinity, produce anti-cancer mediators such as tumor necrosis factor alpha (TNF-α) and granulocyte macrophage colony-stimulating factor (GM-CSF), and generally populate the tumor microenvironments. Yet, the role of MCs in cancer pathologies remains controversial with evidence for both anti-tumor and pro-tumor effects. Here, we review the studies examining the role of MCs in multiple forms of cancer, provide an alternative, MC-based hypothesis underlying the mechanism of therapeutic tumor IgE efficacy in clinical trials, and propose a novel strategy for using tumor-targeted, IgE-sensitized MCs as a platform for developing new cellular cancer immunotherapies. This autologous MC cancer immunotherapy could have several advantages over current cell-based cancer immunotherapies and provide new mechanistic strategies for cancer therapeutics alone or in combination with current approaches.

CD24+ MDSC-DCs Induced by CCL5-Deficiency Showed Improved Antitumor Activity as Tumor Vaccines

Background  Dendritic cell (DC) tumor vaccine has been extensively utilized in preclinical and clinical studies; however, this technique has encountered many difficulties, particularly in late-stage tumor patients. For those, ex vivo-induced DCs are actuallymyeloid-derived suppressive cells-derived DCs (MDSC-DCs). MDSCs with immunosuppressive activity, but not monocytes, became the major DC precursor. Thus, how to enhance antitumor activity of MDSC-DCs is urgent need to address.

Methods  We utilized 4T1 and MC38 tumor-bearing both wildtype and CC chemokine ligand 5 ^−/− (CCL5 ^−/− ) mice as animal models. MDSC-DCs were induced from splenocytes of these mice by granulocyte macrophage–colony stimulating factor/interleukin-4 with or without all-trans-retinoic acid (ATRA) in vitro for 7 days, then incubated with tumor-cell-lysis to treat mouse models for total three doses. For human MDSC-DCs, peripheral bloods from colorectal cancer patients were induced in vitro as murine cells with or without T- lymphocytes depletion to get rid of CCL5.

Results  Flow cytometry analysis showed that MDSCs from CCL5^−/− mice could be induced into a new type of CD24 ⁺ MDSC-DCs in the presence of ATRA, which had more antitumor activity than control. Antibody blocking and adoptive transfer experiments demonstrated that downregulation of regulatory T cells (Tregs) mediated the inhibition of CD24 ⁺ MDSC-DCs on tumor growth. Mechanically, CD24 ⁺ MDSC-DCs inhibited Tregs' polarization by secreting cytokine or coactivators' expression. What's important, decreasing CCL5 protein levels by T- lymphocytes depletion during both murine and human MDSC-DCs in vitro induction could also acquire CD24 ⁺ MDSC-DCs.

Conclusion  Knockdown of CCL5 protein during MDSC-DCs culture might provide a promising method to acquire DC-based tumor vaccines with high antitumor activity.

Plasmacytoid Dendritic Cells and Cancer Immunotherapy

Despite largely disappointing clinical trials of dendritic cell (DC)-based vaccines, recent studies have shown that DC-mediated cross-priming plays a critical role in generating anti-tumor CD8 T cell immunity and regulating anti-tumor efficacy of immunotherapies. These new findings thus support further development and refinement of DC-based vaccines as mono-immunotherapy or combinational immunotherapies. One exciting development is recent clinical studies with naturally circulating DCs including plasmacytoid DCs (pDCs). pDC vaccines were particularly intriguing, as pDCs are generally presumed to play a negative role in regulating T cell responses in tumors. Similarly, DC-derived exosomes (DCexos) have been heralded as cell-free therapeutic cancer vaccines that are potentially superior to DC vaccines in overcoming tumor-mediated immunosuppression, although DCexo clinical trials have not led to expected clinical outcomes. Using a pDC-targeted vaccine model, we have recently reported that pDCs required type 1 conventional DCs (cDC1s) for optimal cross-priming by transferring antigens through pDC-derived exosomes (pDCexos), which also cross-prime CD8 T cells in a bystander cDC-dependent manner. Thus, pDCexos could combine the advantages of both cDC1s and pDCs as cancer vaccines to achieve better anti-tumor efficacy. In this review, we will focus on the pDC-based cancer vaccines and discuss potential clinical application of pDCexos in cancer immunotherapy.

Acute myeloid leukemia cell membrane-coated nanoparticles for cancer vaccination immunotherapy

Cancer vaccines are promising treatments to prevent relapse after chemotherapy in acute myeloid leukemia (AML) patients, particularly for those who cannot tolerate intensive consolidation therapies. Here, we report the development of an AML cell membrane-coated nanoparticle (AMCNP) vaccine platform, in which immune-stimulatory adjuvant-loaded nanoparticles are coated with leukemic cell membrane material. This AMCNP vaccination strategy stimulates leukemia-specific immune responses by co-delivering membrane-associated antigens along with adjuvants to antigen-presenting cells. To demonstrate that this AMCNP vaccine enhances leukemia-specific antigen presentation and T cell responses, we modified a murine AML cell line to express membrane-bound chicken ovalbumin as a model antigen. AMCNPs were efficiently acquired by antigen-presenting cells in vitro and in vivo and stimulated antigen cross-presentation. Vaccination with AMCNPs significantly enhanced antigen-specific T cell expansion and effector function compared with control vaccines. Prophylactic vaccination with AMCNPs enhanced cellular immunity and protected against AML challenge. Moreover, in an AML post-remission vaccination model, AMCNP vaccination significantly enhanced survival in comparison to vaccination with whole leukemia cell lysates. Collectively, AMCNPs retained AML-specific antigens, elicited enhanced antigen-specific immune responses, and provided therapeutic benefit against AML challenge.

Safety and efficacy of dendritic cell-based immunotherapy (DCVAC/LuCa) combined with carboplatin/pemetrexed for patients with advanced non-squamous non-small-cell lung cancer without oncogenic drivers

Background

Our prospective, open-label, single-arm phase II study investigated the safety and efficacy of DCVAC/LuCa (dendritic cell vaccines for lung cancer) combined with standard carboplatin/pemetrexed in advanced non-squamous (nsq) non-small-cell lung cancer (NSCLC).

Patients and methods

Eligible patients had stage IV nsq NSCLC without oncogenic drivers and had not received prior systemic cancer therapy. Treatment consisted of carboplatin/pemetrexed for up to 6 cycles followed by 21 cycles of pemetrexed maintenance or until progression or intolerance. Non-progression patients after two cycles of chemotherapy started to receive DCVAC/LuCa subcutaneously (s.c.) on day 15 of cycle 3, and thereafter q3w (day 15 of chemotherapy cycles) for up to 15 doses. Dosing of DCVAC/LuCa s.c. varied among patients depending on the baseline number of leucocytes but remained constant for each single patient. Safety was assessed by adverse events (AEs), treatment-related adverse events (TRAEs), serious adverse events (SAEs), and adverse events of special interest (AESIs). Efficacy was measured by overall survival (OS), progression-free survival (PFS), time to progression (TTP), and objective response rate (ORR).

Results

Sixty-one patients were enrolled. In the safety population (n = 60), eight patients (13.33%) had grade 3 or greater TRAEs, and six patients (10.0%) showed SAEs which were not related to leukapheresis or DC vaccination. Six grade 1 AEs were considered to be related to leukapheresis. No AESIs or DCVAC/LuCa-induced AEs were observed. The 2-year survival rate in the modified intention-to-treat population (n = 44) was 52.57%. Median OS was not reached. Median PFS was 8.0 months, median TTP was 10.2 months, and the ORR was 31.82%.

Conclusion

In treatment-naïve stage IV nsq NSCLC patients without oncogenic drivers, the combination of carboplatin/pemetrexed and DCVAC/LuCa was well tolerated and showed promising efficacy. Therefore, a study to prove our immunotherapeutic concept in a randomized phase III trial is planned.

•

We investigated the safety and efficacy of DCVAC/LuCa combined with standard carboplatin/pemetrexed in nsq NSCLC.

•

The combination therapy showed a favorable tolerability profile in a selected Chinese population.

•

The 2-year survival rate in the modified intention-to-treat population (n = 44) was 52.57%.

Imaging dendritic cell functions

Dendritic cells (DCs) are crucial for the appropriate initiation of adaptive immune responses. During inflammation, DCs capture antigens, mature, and migrate to lymphoid tissues to present foreign material to naïve T cells. These cells get activated and differentiate either into pathogen-specific cytotoxic CD8⁺ T cells that destroy infected cells or into CD4⁺ T helper cells that, among other effector functions, orchestrate antibody production by B cells. DC-mediated antigen presentation is equally important in non-inflammatory conditions. Here, DCs mediate induction of tolerance by presenting self-antigens or harmless environmental antigens and induce differentiation of regulatory T cells or inactivation of self-reactive immune cells. Detailed insights into the biology of DCs are, therefore, crucial for the development of novel vaccines as well as the prevention of autoimmune diseases. As in many other life science areas, our understanding of DC biology would be extremely restricted without bioimaging, a compilation of methods that visualize biological processes. Spatiotemporal tracking of DCs relies on various imaging tools, which not only enable insights into their positioning and migration within tissues or entire organs but also allow visualization of subcellular and molecular processes. This review aims to provide an overview of the imaging toolbox and to provide examples of diverse imaging techniques used to obtain fundamental insights into DC biology.

Blood DCs activated with R848 and poly(I:C) induce antigen-specific immune responses against viral and tumor-associated antigens

Monocyte-derived Dendritic cells (DCs) have successfully been employed to induce immune responses against tumor-associated antigens in patients with various cancer entities. However, objective clinical responses have only been achieved in a minority of patients. Additionally, generation of GMP-compliant DCs requires time- and labor-intensive cell differentiation. In contrast, Blood DCs (BDCs) require only minimal ex vivo handling, as differentiation occurs in vivo resulting in potentially better functional capacities and survival. We aimed to identify a protocol for optimal in vitro activation of BDCs including the three subsets pDCs, cDC1s, and cDC2s. We evaluated several TLR ligand combinations and demonstrated that polyinosinic:polycytidylic acid [poly(I:C)] and R848, ligands for TLR3 and TLR7/8, respectively, constituted the optimal combination for inducing a positive co-stimulatory profile in all BDC subsets. In addition, TLR3 and TLR7/8 activation led to high secretion of IFN-α and IL-12p70. Simultaneous as opposed to separate tailored activation of pDCs and cDCs increased immunostimulatory capacities, suggesting that BDC subsets engage in synergistic cross-talk during activation. Stimulation of BDCs with this protocol resulted in enhanced migration, high NK-cell activation, and potent antigen-specific T-cell induction.

We conclude that simultaneous activation of all BDC subsets with a combination of R848 + poly(I:C) generates highly immunostimulatory DCs. These results support further investigation and clinical testing, as standalone or in conjunction with other immunotherapeutic strategies including adoptive T-cell transfer and checkpoint inhibition.

Modulation of the immune response by heterogeneous monocytes and dendritic cells in lung cancer

Different subpopulations of monocytes and dendritic cells (DCs) may have a key impact on the modulation of the immune response in malignancy. In this review, we summarize the monocyte and DCs heterogeneity and their function in the context of modulating the immune response in cancer. Subgroups of monocytes may play opposing roles in cancer, depending on the tumour growth and progression as well as the type of cancer. Monocytes can have pro-tumour and anti-tumour functions and can also differentiate into monocyte-derived DCs (moDCs). MoDCs have a similar antigen presentation ability as classical DCs, including cross-priming, a process by which DCs activate CD8 T-cells by cross-presenting exogenous antigens. DCs play a critical role in generating anti-tumour CD8 T-cell immunity. DCs have plastic characteristics and show distinct phenotypes depending on their mature state and depending on the influence of the tumour microenvironment. MoDCs and other DC subsets have been attracting increased interest owing to their possible beneficial effects in cancer immunotherapy. This review also highlights key strategies deploying specific DC subpopulations in combination with other therapies to enhance the anti-tumour response and summarizes the latest ongoing and completed clinical trials using DCs in lung cancer.

Fecal microbiota composition associates with the capacity of human peripheral blood monocytes to differentiate into immunogenic dendritic cells in vitro

Although promising for active immunization in cancer patients, dendritic cells (DCs) vaccines generated in vitro display high inter-individual variability in their immunogenicity, which mostly limits their therapeutic efficacy. Gut microbiota composition is a key emerging factor affecting individuals' immune responses, but it is unknown how it affects the variability of donors' precursor cells to differentiate into immunogenic DCs in vitro. By analyzing gut microbiota composition in 14 healthy donors, along with the phenotype and cytokines production by monocyte-derived DCs, we found significant correlations between immunogenic properties of DC and microbiota composition. Namely, donors who had higher α-diversity of gut microbiota and higher abundance of short-chain fatty acid (SCFAs) and SCFA-producing bacteria in feces, displayed lower expression of CD1a on immature (im)DC and higher expression of ILT-3, costimulatory molecules (CD86, CD40) proinflammatory cytokines (TNF-α, IL-6, IL-8) and IL-12p70/IL-10 ratio, all of which correlated with their lower maturation potential and immunogenicity upon stimulation with LPS/IFNγ, a well-known Th1 polarizing cocktail. In contrast, imDCs generated from donors with lower α-diversity and higher abundance of Bifidobacterium and Collinsella in feces displayed higher CD1a expression and higher potential to up-regulate CD86 and CD40, increase TNF-α, IL-6, IL-8 production, and IL-12p70/IL-10 ratio upon stimulation. These results emphasize the important role of gut microbiota on the capacity of donor precursor cells to differentiate into immunogenic DCs suitable for cancer therapy, which could be harnessed for improving the actual and future DC-based cancer therapies.

Dendritic cell therapy with CD137L-DC-EBV-VAX in locally recurrent or metastatic nasopharyngeal carcinoma is safe and confers clinical benefit

INTRODUCTION

Epstein-Barr virus (EBV) is associated with nasopharyngeal carcinoma (NPC), and provides a target for a dendritic cell (DC) vaccine. CD137 ligand (CD137L) expressed on antigen presenting cells, costimulates CD137-expressing T cells, and reverse CD137L signaling differentiates monocytes to CD137L-DC, a type of DC, which is more potent than classical DC in stimulating T cells.

METHODS

In this phase I study, patients with locally recurrent or metastatic NPC were administered CD137L-DC pulsed with EBV antigens (CD137L-DC-EBV-VAX).

RESULTS

Of the 12 patients treated, 9 received full 7 vaccine doses with a mean administered cell count of 23.9 × 10⁶ per dose. Treatment was well tolerated with only 4 cases of grade 1 related adverse events. A partial response was obtained in 1 patient, and 4 patients are still benefitting from a progression free survival (PFS) of currently 2-3 years. The mean pre-treatment neutrophil: lymphocyte ratio was 3.4 and a value of less than 3 was associated with prolonged median PFS. Progressors were characterized by a high frequency of naïve T cells but a low frequency of CD8⁺ effector T cells while patients with a clinical benefit (CB) had a high frequency of memory T cells. Patients with CB had lower plasma EBV DNA levels, and a reduction after vaccination.

CONCLUSION

CD137L-DC-EBV-VAX was well tolerated. The use of CD137L-DC-EBV-VAX is demonstrated to be safe. Consistent results were obtained from all 12 patients, indicating that CD137L-DC-EBV-VAX induces an anti-EBV and anti-NPC immune response, and warranting further studies in patients post effective chemotherapy.

PRECIS

The first clinical testing of CD137L-DC, a new type of monocyte-derived DC, finds that CD137L-DC are safe, and that they can induce an immune response against Epstein-Barr virus-associated nasopharyngeal carcinoma that leads to tumor regression or prevents tumor progression.

Identification of immune infiltration-related LncRNA FAM83C-AS1 for predicting prognosis and immunotherapy response in colon cancer

BACKGROUND

Increasing evidence has demonstrated the functional relevance of long non-coding RNAs (lncRNAs) to the occurrence and progression of tumors. However, the role of lncRNA FAM83C-AS1 in tumors remains unclear. We aim to prove the relationship between FAM83C-AS1 and colon cancer (CCa).

METHODS

The expression level of FAM83C-AS1 in CCa were explored through bioinformatics analysis. Receiver operating characteristic (ROC) curves, Kaplan-Meier method and Cox regression analysis were used to evaluated to its roles in the prognosis of CCa. The biological function was explored through gene set enrichment analysis (GSEA). The correlation between FAM83C-AS1 expression and immune infiltration and immunotherapy response was analyzed through single-sample GSEA (ssGSEA) and Spearman correlation.

RESULTS

FAM83C-AS1 was up-regulated in multiple cancers including CCa. Increased FAM83C-AS1 expression in CCa was correlated with advanced clinical pathologic characteristics (histological type, M stage; p < 0.05). ROC curve suggested the significant diagnostic and prognostic ability of FAM83C-AS1 (AUC = 0.759). High FAM83C-AS1 expression predicted a poorer overall survival (OS, p = 0.033) and disease-free survival (DFS, p = 0.043), and FAM83C-AS1 expression was independently correlated with OS in CCa patients (HR:1.69; 95% CI:1.07-2.67; p = 0.024). In addition, GSEA suggested the involvement of FAM83C-AS1 in immune-related pathways. We also found the correlation of FAM83C-AS1 with DC cells and T helper cells and a potential of the measurement in response to immunotherapy.

CONCLUSION

High expression of FAM83C-AS1 indicated poor prognosis and correlation with immune infiltrations and immune response in CCa, and it may be a promising biomarker of prognosis and response to immunotherapy for CCa.

Modeling codelivery of CD73 inhibitor and dendritic cell-based vaccines in cancer immunotherapy

Dendritic cells (DCs) are the dominant class of antigen-presenting cells in humans; therefore, a range of DC-based approaches have been established to promote an immune response against cancer cells. The efficacy of DC-based immunotherapeutic approaches is markedly affected by the immunosuppressive factors related to the tumor microenvironment, such as adenosine. In this paper, based on immunological theories and experimental data, a hybrid model is designed that offers some insights into the effects of DC-based immunotherapy combined with adenosine inhibition. The model combines an individual-based model for describing tumor-immune system interactions with a set of ordinary differential equations for adenosine modeling. Computational simulations of the proposed model clarify the conditions for the onset of a successful immune response against cancer cells. Global and local sensitivity analysis of the model highlights the importance of adenosine blockage for strengthening effector cells. The model is used to determine the most effective suppressive mechanism caused by adenosine, proper vaccination time, and the appropriate time interval between injections.

β2-Integrin Adhesion Regulates Dendritic Cell Epigenetic and Transcriptional Landscapes to Restrict Dendritic Cell Maturation and Tumor Rejection

Dendritic cells (DC), the classic antigen-presenting cells of the immune system, switch from an adhesive, phagocytic phenotype in tissues, to a mature, nonadhesive phenotype that enables migration to lymph nodes to activate T cells and initiate antitumor responses. Monocyte-derived DCs are used in cancer immunotherapy, but their clinical efficacy is limited. Here, we show that cultured bone marrow-derived DCs (BM-DC) expressing dysfunctional β2-integrin adhesion receptors displayed enhanced tumor rejection capabilities in B16.OVA and B16-F10 melanoma models. This was associated with an increased CD8⁺ T-cell response. BM-DCs expressing dysfunctional β2-integrins or manipulated to disrupt integrin adhesion or integrin/actin/nuclear linkages displayed spontaneous maturation in ex vivo cultures (increased costimulatory marker expression, IL12 production, and 3D migration capabilities). This spontaneous maturation was associated with an altered DC epigenetic/transcriptional profile, including a global increase in chromatin accessibility and H3K4me3/H3K27me3 histone methylation. Genome-wide analyses showed that H3K4me3 methylation was increased on DC maturation genes, such as CD86, Il12, Ccr7, and Fscn1, and revealed a role for a transcription factor network involving Ikaros and RelA in the integrin-regulated phenotype of DCs. Manipulation of the integrin-regulated epigenetic landscape in wild-type ex vivo-cultured BM-DCs enhanced their functionality in tumor rejection in vivo. Thus, β2-integrin-mediated adhesion to the extracellular environment plays an important role in restricting DC maturation and antitumor responses through regulation of the cellular epigenetic and transcriptional landscape. Targeting β2-integrins could therefore be a new strategy to improve the performance of current DC-based cancer immunotherapies.

Critical View of Novel Treatment Strategies for Glioblastoma: Failure and Success of Resistance Mechanisms by Glioblastoma Cells

According to the invasive nature of glioblastoma, which is the most common form of malignant brain tumor, the standard care by surgery, chemo- and radiotherapy is particularly challenging. The presence of glioblastoma stem cells (GSCs) and the surrounding tumor microenvironment protects glioblastoma from recognition by the immune system. Conventional therapy concepts have failed to completely remove glioblastoma cells, which is one major drawback in clinical management of the disease. The use of small molecule inhibitors, immunomodulators, immunotherapy, including peptide and mRNA vaccines, and virotherapy came into focus for the treatment of glioblastoma. Although novel strategies underline the benefit for anti-tumor effectiveness, serious challenges need to be overcome to successfully manage tumorigenesis, indicating the significance of developing new strategies. Therefore, we provide insights into the application of different medications in combination to boost the host immune system to interfere with immune evasion of glioblastoma cells which are promising prerequisites for therapeutic approaches to treat glioblastoma patients.

Differential infection of murine and human dendritic cell subsets by oncolytic vesicular stomatitis virus variants

Oncolytic viruses (OVs) can eradicate tumor cells and elicit antitumor immunity. VSV-GP, a chimeric vesicular stomatitis virus (VSV) with the glycoprotein (GP) of the lymphocytic choriomeningitis virus, is a promising new OV candidate. However, the interaction of VSV-GP with host immune cells is not fully understood. Dendritic cells (DCs) are essential for inducing efficient antitumor immunity. Thus, we aimed to investigate the interaction of VSV-GP with different murine and human DCs subsets in direct comparison to the less cytopathic variant VSV-dM51-GP and wild type VSV. Immature murine bone marrow-derived DCs (BMDCs) were equally infected and killed by VSV and VSV-GP. Human monocyte-derived DCs (moDCs) were more permissive to VSV. Interestingly, VSV-dM51-GP induced maturation instead of killing in both BMDCs and moDCs as well as a pronounced release of pro-inflammatory cytokines. Importantly, matured BMDCs and moDCs were no longer susceptible to VSV-GP infection. Mouse splenic conventional DC type 1 (cDC1) could be infected ex vivo by VSV and VSV-GP to a higher extent than cDC2. Systemic infection of mice with VSV-GP and VSV-dM51-GP resulted in strong activation of cDCs despite low infection rates in spleen and tumor tissue. Human blood cDC1 were equally infected by VSV and VSV-GP, whereas cDC2 showed preferential infection with VSV. Our study demonstrated differential DC infection, activation, and cytokine production after the treatment with VSV and VSV-GP variants among species and subsets, which should be taken into account when investigating immunological mechanisms of oncolytic virotherapy in mouse models and human clinical trials.

DC-Derived Exosomes for Cancer Immunotherapy

As the initiators of adaptive immune responses, DCs play a central role in regulating the balance between CD8 T cell immunity versus tolerance to tumor antigens. Exploiting their function to potentiate host anti-tumor immunity, DC-based vaccines have been one of most promising and widely used cancer immunotherapies. However, DC-based cancer vaccines have not achieved the promised success in clinical trials, with one of the major obstacles being tumor-mediated immunosuppression. A recent discovery on the critical role of type 1 conventional DCs (cDC1s) play in cross-priming tumor-specific CD8 T cells and determining the anti-tumor efficacy of cancer immunotherapies, however, has highlighted the need to further develop and refine DC-based vaccines either as monotherapies or in combination with other therapies. DC-derived exosomes (DCexos) have been heralded as a promising alternative to DC-based vaccines, as DCexos are more resistance to tumor-mediated suppression and DCexo vaccines have exhibited better anti-tumor efficacy in pre-clinical animal models. However, DCexo vaccines have only achieved limited clinical efficacy and failed to induce tumor-specific T cell responses in clinical trials. The lack of clinical efficacy might be partly due to the fact that all current clinical trials used peptide-loaded DCexos from monocyte-derived DCs. In this review, we will focus on the perspective of expanding current DCexo research to move DCexo cancer vaccines forward clinically to realize their potential in cancer immunotherapy.

Facile Transformation of Murine and Human Primary Dendritic Cells into Robust and Modular Artificial Antigen-Presenting Systems by Intracellular Hydrogelation

The growing enthusiasm for cancer immunotherapies and adoptive cell therapies has prompted increasing interest in biomaterials development mimicking natural antigen-presenting cells (APCs) for T-cell expansion. In contrast to conventional bottom-up approaches aimed at layering synthetic substrates with T-cell activation cues, transformation of live dendritic cells (DCs) into artificial APCs (aAPCs) is demonstrated herein using a facile and minimally disruptive hydrogelation technique. Through direct intracellular permeation of poly(ethylene glycol) diacrylate (PEG-DA) hydrogel monomer and UV-activated radical polymerization, intracellular hydrogelation is rapidly accomplished on DCs with minimal influence on cellular morphology and surface antigen display, yielding highly robust and modular cell-gel hybrid constructs amenable to peptide antigen exchange, storable by freezing and lyophilization, and functionalizable with cytokine-releasing carriers for T-cell modulation. The DC-derived aAPCs are shown to induce prolonged T-cell expansion and improve anticancer efficacy of adoptive T-cell therapy in mice compared to nonexpanded control T cells, and the gelation technique is further demonstrated to stabilize primary DCs derived from human donors. The work presents a versatile approach for generating a new class of cell-mimicking biomaterials and opens new venues for immunological interrogation and immunoengineering.

IL-35 Regulates the Function of Immune Cells in Tumor Microenvironment

Interleukin-35 (IL-35) is a heterodimeric cytokine composed of Epstein-Barr virus-induced gene 3 (EBI3) and IL-12p35 that has recently been shown to play diverse and important roles in the tumor microenvironment (TME). Owing to its immunosuppressive activity and ability to promote tumor growth and progression, IL-35 is widely recognized as a key mediator of TME status. Immune cells are key mediators of diverse tumor-related phenotypes, and immunosuppressive cytokines such as IL-35 can promote tumor growth and metastasis in TME. These influences should be considered together. Since tumor immunotherapy based on immune checkpoint blockade remains ineffective in many patients due to tumoral resistance, a new target or efficacy enhancing factor is urgently needed. Suppressing IL-35 production and activity has been demonstrated as an effective factor that inhibits tumor cells viability, and further investigation of this cytokine is warranted. However, the mechanistic basis for IL-35-mediated regulation of immune cells in the TME remains to be fully clarified. In the present review, we explore the roles of IL-35 in regulating immune cells within the TME. In addition, we highlight IL-35 as a specific immunological target and discuss its possible relevance in the context of immunotherapy. Lastly, we sought to summarize potential future research directions that may guide the advancement of current understanding regarding the role of this important cytokine as a regulator of oncogenesis.

Dendritic cell immune potency on 2D and in 3D collagen matrices

Dendritic cells (DCs) are antigen-presenting cells capable of either activating the immune response or inducing and maintaining immune tolerance. Understanding how biophysical properties affect DC behaviors will provide insight into the biology of a DC and its applications. In this work, we studied how cell culture dimensionality (two-dimensional (2D) and three-dimensional (3D)), and matrix density of 3D collagen matrices modulate differentiation and functions of DCs. Besides, we aimed to point out the different conceptual perspectives in modern immunological research, namely tissue-centric and cell-centric perspectives. The tissue-centric perspective intends to reveal how specific microenvironments dictate DC differentiation and in turn modulate DC functionalities, while the cell-centric perspective aims to demonstrate how pre-differentiated DCs behave in specific microenvironments. DC plasticity was characterized in terms of cell surface markers and cytokine secretion profiles. Subsequently, antigen internalization and T cell activation were quantified to demonstrate the cellular functions of immature DCs (iDCs) and mature DCs (mDCs), respectively. In the tissue-centric perspective, we found that expressed surface markers and secreted cytokines of both iDCs and mDCs are generally higher in 2D culture, while they are regulated by matrix density in 3D culture. In contrast, in the cell-centric perspective, we found enhanced expression of cell surface markers as well as distinct cytokine secretion profiles in both iDCs and mDCs. By analyzing cellular functions of cells in the tissue-centric perspective, we found matrix density dependence in antigen uptake by iDCs, as well as on mDC-mediated T cell proliferation in 3D cell culture. On the other hand, in the cell-centric perspective, both iDCs and mDCs appeared to lose their functional potentials to internalization antigen and T cell stimulation. Additionally, mDCs from tissue- and cell-centric perspectives modulated T cell differentiation by their distinct cytokine secretion profiles towards Th1 and Th17, respectively. In sum, our work emphasizes the importance of dimensionality, as well as collagen fibrillar density in the regulation of the immune response of DCs. Besides this, we demonstrated that the conceptual perspective of the experimental design could be an essential key point in research in immune cell-material interactions and biomaterial-based disease models of immunity.

Thapsigargin-Stimulated LAD2 Human Mast Cell Line Is a Potent Cellular Adjuvant for the Maturation of Monocyte-Derived Dendritic Cells for Adoptive Cellular Immunotherapy

The preparation of dendritic cells (DCs) for adoptive cellular immunotherapy (ACI) requires the maturation of ex vivo-produced immature(i) DCs. This maturation ensures that the antigen presentation triggers an immune response towards the antigen-expressing cells. Although there is a large number of maturation agents capable of inducing strong DC maturation, there is still only a very limited number of these agents approved for use in the production of DCs for ACI. In seeking novel DC maturation agents, we used differentially activated human mast cell (MC) line LAD2 as a cellular adjuvant to elicit or modulate the maturation of ex vivo-produced monocyte-derived iDCs. We found that co-culture of iDCs with differentially activated LAD2 MCs in serum-containing media significantly modulated polyinosinic:polycytidylic acid (poly I:C)-elicited DC maturation as determined through the surface expression of the maturation markers CD80, CD83, CD86, and human leukocyte antigen(HLA)-DR. Once iDCs were generated in serum-free conditions, they became refractory to the maturation with poly I:C, and the LAD2 MC modulatory potential was minimized. However, the maturation-refractory phenotype of the serum-free generated iDCs was largely overcome by co-culture with thapsigargin-stimulated LAD2 MCs. Our data suggest that differentially stimulated mast cells could be novel and highly potent cellular adjuvants for the maturation of DCs for ACI.

LncRNA ST7-AS1 is a Potential Novel Biomarker and Correlated With Immune Infiltrates for Breast Cancer

Background: Long noncoding RNA (lncRNA) ST7-AS1 can be observed in various cancers, but its role in breast cancer (BRC) remains unclear. Our aim is to, on the basis of The Cancer Genome Atlas (TCGA) database, prove the correlation between lncRNA ST7-AS1 and BRC.

Methods: The lncRNA ST7-AS1 expression and its roles in the prognosis of BRC were explored using data from the TCGA database. The expression level of lncRNA ST7-AS1 in BRC samples was detected using RT-PCR. The 1-, 3-, or 5-year survival rate was predicted using a nomogram established through Cox proportional hazard regression. At last, the biological function was explored through gene ontology (GO) analysis and gene set enrichment analysis (GSEA). The hallmark pathways significantly involved in hub genes were described through functional enrichment analysis. The correlation between lncRNA ST7-AS1 expression and immune infiltration was analyzed through single-sample GSEA (ssGSEA).

Results: LncRNA ST7-AS1 expression was downregulated in BRC. Decreased lncRNA ST7-AS1 expression in BRC was correlated with advanced clinical pathologic characteristics (high grade, histological type, age, menopause status, and HER2 status), survival time, and poor prognosis. The nomogram was established for using lncRNA ST7-AS1 to predict 1-, 3-, or 5-year survival in patients with BRC. In addition, GO and pathway analyses suggested the involvement of lncRNA ST7-AS1 in cell cycle, DNA repair, and immune cell infiltration in the BRC immune microenvironment. We found the correlation of lncRNA ST7-AS1 with T helper cells and DC cells.

Conclusion: Low expression of lncRNA ST7-AS1 indicates poor prognosis and has an impact on cell cycle, DNA repair, and proportion of infiltrating immune cells in the BRC microenvironment. Therefore, lncRNA ST7-AS1 can be used as a protective prognostic marker and a potential treatment target for BRC.

A novel therapeutic modality using CRISPR-engineered dendritic cells to treat allergies

Despite the important roles of dendritic cells (DCs) in airway allergies, current therapeutic strategies such as drugs, allergen immunotherapy and biologics haven't been targeted at them. In this study, we established a promising DC-based therapeutic approach for the alleviation of allergic rhinitis (AR)-associated allergic reactions, using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated targeted gene disruption. RNA sequencing analysis revealed upregulation of vacuolar protein sorting 37 B (VPS37B) in AR-derived DCs, indicating a novel molecular target. Following antigen presentation, VPS37A and VPS37B enabled endocytosis of the mannose receptor, which recognizes the house dust mite (HDM) allergen Der p 1. DCs with targeted disruption of VPS37A/B alleviated Th2 cytokine production when co-cultured in vitro with allogeneic naïve CD4⁺ T cell from patients with AR. Furthermore, nasal administration of Vps37a/b-disrupted bone marrow DCs to a mouse model of AR resulted in strongly reduced AR-related symptoms. Thus, this novel modality using genetically engineered DCs can provide an effective therapeutic and preventative strategy for allergic diseases.

Autologous cervical tumor lysate pulsed dendritic cell stimulation followed by cisplatin treatment abrogates FOXP3+ cells in vitro

Objective

Dendritic cells (DCs) are administered as immunotherapeutic adjuvants after the completion of standard treatment in most settings. However, our Phase I trial indicated that one patient out of four, who received autologous tumor lysate-pulsed dendritic cell (TLDC) also received cisplatin chemotherapy and experienced complete regression of her lung lesion, continuing to be disease free till date. Hence, the objective of our current study is to evaluate the sustenance or augmentation of immune responses when autologous human papillomavirus positive cervical tumor lysate pulsed DC- are combined with cisplatin, using co-culture assays in vitro.

Methods

Before treatment, peripheral blood and punch biopsy samples were collected from 23 cervical cancer patients after obtaining an informed consent. DC functionality was confirmed through phenotypic and functional assays using autologous peripheral blood mononuclear cells as responders. For cisplatin experiments, the drug was added at 150, 200 (clinical dose equivalent), and 400 µM concentrations to DCs alone or DC-T cell co-cultures. Phenotypic assessment and functional characterization of DCs was done using flow cytometry. Cytokine enzyme-linked immunosorbent assay and interferon (IFN)-γ enzyme-linked immune absorbent spot assays were also performed.

Results

The functionality of TLDCs was not compromised upon cisplatin treatment in vitro even at the highest (400 μM) concentration. Even though cisplatin treatment reduced the secretion of IFN-γ and interleukin (IL)-12p40 in co-cultures stimulated with TLDCs, this effect was not significant (p>0.05). A doubling of IFN-γ secretion following cisplatin treatment was observed in at least one of three independent experiments. Additional experiments showed a reduction in both FOXP3+ regulatory T cells and IL-10 levels.

Conclusion

Our results provide evidence that cisplatin treatment may be given after autologous TLDC administration to maintain or improve a productive anti-tumor response in vaccinated patients.