TIM-3 blockade enhances IL-12-dependent antitumor immunity by promoting CD8+ T cell and XCR1+ dendritic cell spatial co-localization

Evolving CAR T-Cell Therapy to Overcome the Barriers in Treating Pediatric Central Nervous System Tumors

SIGNIFICANCE

CNS tumors are the leading cause of cancer-related death in children, highlighting the dire need for new treatment strategies. CAR T cells represent a unique approach, distinct from the cytotoxic chemotherapies and small-molecule inhibitors that have dominated the clinical trial space for decades. Phase I CAR T-cell trials have shown feasibility and possible efficacy against pediatric CNS tumors; however, many challenges must be overcome if these therapeutics are going to be beneficial to most affected children. Although rapid translational development and early-phase trials have quickly evolved our understanding, the pediatric CNS CAR T-cell community now yearns for critical assessments and open dialogue about overcoming the remaining obstacles ahead.

Multifactorial stroma-mediated resistance is a major contributor to residual disease under targeted therapies in lung cancers

Despite inducing strong and durable clinical responses, targeted therapies do not eliminate advanced cancers, as a subset of tumor cells survives within residual tumors, eventually developing resistance. The ability of tumor cells to avoid therapeutic elimination can be mediated both by cell-intrinsic and microenvironmental mechanisms. Whilst the specific molecular mediators of cell-intrinsic and microenvironmental resistance are well understood, their relative contribution to in vivo therapeutic responses remains poorly defined. Using spatial histological inferences from experimental models of ALK+ NSCLC, we found that peristromal niches protected tumor cells from therapeutic elimination in vivo, enabling in vivo persistence. Whereas the development of bona fide resistance is associated with the development of the development of cell-intrinsic resistance, relapse of tumor growth reflects a combined effect of both cell-intrinsic and microenvironmental mechanisms. Mechanistically, the protective effect of the peristromal niche is not reducible to a single mechanism, instead reflecting a combined effect of multiple juxtacrine and paracrine mediators. The lack of reducibility to a single molecular mediator presents an obvious challenge to the therapeutic paradigms of targeting individual resistance mechanisms. We found that this challenge could be mitigated by shifting the therapeutic focus to orthogonal collateral sensitivities of residual tumors. Exploiting adaptive upregulation of HER2, associated with both cell-intrinsic and microenvironmental persistence, using the antibody-drug conjugate T-DXd strongly enhanced the effect of targeted therapies and suppressed the development of resistance.

Dendritic cell maturation in cancer

Dendritic cells (DCs) are specialized antigen-presenting cells that are present at low abundance in the circulation and tissues; they serve as crucial immune sentinels by continually sampling their environment, migrating to secondary lymphoid organs and shaping adaptive immune responses through antigen presentation. Owing to their ability to orchestrate tolerogenic or immunogenic responses to a specific antigen, DCs have a pivotal role in antitumour immunity and the response to immune checkpoint blockade and other immunotherapeutic approaches. The multifaceted functions of DCs are acquired through a complex, multistage process called maturation. Although the role of inflammatory triggers in driving DC maturation was established decades ago, less is known about DC maturation in non-inflammatory contexts, such as during homeostasis and in cancer. The advent of single-cell technologies has enabled an unbiased, high-dimensional characterization of various DC states, including mature DCs. This approach has clarified the molecular programmes associated with DC maturation and also revealed how cancers exploit these pathways to subvert immune surveillance. In this Review, we discuss the mechanisms by which cancer disrupts DC maturation and highlight emerging therapeutic opportunities to modulate DC states. These insights could inform the development of DC-centric immunotherapies, expanding the arsenal of strategies to enhance antitumour immunity.

Tissue-specific properties of type 1 dendritic cells in lung cancer: implications for immunotherapy

Checkpoint inhibitors have led to remarkable benefits in non-small cell lung cancer (NSCLC), yet response rates remain below expectations. High-dimensional analysis and mechanistic experiments in clinical samples and relevant NSCLC models uncovered the immune composition of lung cancer tissues, providing invaluable insights into the functional properties of tumor-infiltrating T cells and myeloid cells. Among myeloid cells, type 1 conventional dendritic cells (cDC1s) stand out for their unique ability to induce effector CD8 T cells against neoantigens and coordinate antitumoral immunity. Notably, lung resident cDC1 are particularly abundant and long-lived and express a unique tissue-specific gene program, underscoring their central role in lung immunity. Here, we discuss recent insights on the induction and regulation of antitumoral T cell responses in lung cancer, separating it from the tissue-agnostic knowledge generated from heterogeneous tumor models. We focus on the most recent studies dissecting functional states and spatial distribution of lung cDC1 across tumor stages and their impact on T cell responses to neoantigens. Finally, we highlight relevant gaps and emerging strategies to harness lung cDC1 immunostimulatory potential.

Epigenetic regulators combined with tumour immunotherapy: current status and perspectives

Immunotherapy, particularly immune checkpoint inhibitor therapy, has demonstrated clinical benefits in solid tumours. Despite its satisfactory clinical efficacy, it still faces several issues, such as limited eligibility, low response rates and cytotoxicity. Cancer epigenetics implies that tumour cells exhibit unique phenotypes because of their unique characteristics, thus reprogramming of the epigenome holds promise for cancer therapy. Epigenetic regulation plays an important role in regulating gene expression during tumour development and maintenance. Epigenetic regulators induce cancer cell cycle arrest, apoptosis and differentiation of cancer cells, thereby exerting anti-tumour effects. Recent studies have revealed a significant correlation between epigenetic regulatory factors and immune checkpoint therapy. Epigenetics can modulate various aspects of the tumour immune microenvironment and immune response to enhance the sensitivity of immunotherapy, such as lowering the concentration required and mitigating cytotoxicity. This review primarily discusses DNA methyltransferase inhibitors, histone deacetylase inhibitors, enhancer of zeste homolog 2 inhibitors and lysine-specific demethylase 1 inhibitors, which are associated with transcriptional repression. This repression alters the expression of genes involved in the immune checkpoint, thereby enhancing the effectiveness of immunotherapy. We also discuss the potential and challenges of tumour immunotherapy and highlight its advantages, application challenges and clinical research on integrating epigenetic regulatory factors with tumour immunotherapy.

Involvement of Tim-3 in Maternal-fetal Tolerance: A Review of Current Understanding

As the first T cell immunoglobulin mucin (Tim) family member to be identified, Tim-3 is a powerful immune checkpoint that functions in immunoregulation and induction of tolerance. Conventionally, Tim-3 is considered to play a role in adaptive immunity, especially in helper T cell-mediated immune responses. As researches progress, Tim-3 has been detected in a wider range of cell types, modulating cell function through ligand-receptor interactions and other pathways. Strikingly, Tim-3 plays a pivotal role in maternal-fetal tolerance by regulating immune cell functions and orchestrating the maternal-fetal cross-talk. In this review, we elaborate on the involvement of Tim-3 in immunology, with a focus on its participation in maternal-fetal tolerance to provide new insights into immunoregulation during pregnancy. Our work will be helpful in further understanding the pathogenesis of pregnancy-related diseases and will inspire new strategies for their diagnosis and treatment.

Guidelines for preparation and flow cytometry analysis of human nonlymphoid tissue DC

This article is part of the Dendritic Cell Guidelines article series, which provides a collection of state-of-the-art protocols for the preparation, phenotype analysis by flow cytometry, generation, fluorescence microscopy, and functional characterization of mouse and human dendritic cells (DC) from lymphoid organs, and various nonlymphoid tissues. Within this article, detailed protocols are presented that allow for the generation of single-cell suspensions from human nonlymphoid tissues including lung, skin, gingiva, intestine as well as from tumors and tumor-draining lymph nodes with a subsequent analysis of dendritic cells by flow cytometry. Further, prepared single-cell suspensions can be subjected to other applications including cellular enrichment procedures, RNA sequencing, functional assays, etc. While all protocols were written by experienced scientists who routinely use them in their work, this article was also peer-reviewed by leading experts and approved by all co-authors, making it an essential resource for basic and clinical DC immunologists.

The role of Tim-3 blockade in the tumor immune microenvironment beyond T cells

Numerous preclinical studies have demonstrated the inhibitory function of T cell immunoglobulin mucin domain-containing protein 3 (Tim-3) on T cells as an inhibitory receptor, leading to the clinical development of anti-Tim-3 blocking antibodies. However, recent studies have shown that Tim-3 is expressed not only on T cells but also on multiple cell types in the tumor microenvironment (TME), including dendritic cells (DCs), natural killer (NK) cells, macrophages, and tumor cells. Therefore, Tim-3 blockade in the immune microenvironment not only affect the function of T cells but also influence the functions of other cells. For example, Tim-3 blockade can enhance the ability of DCs to regulate innate and adaptive immunity. The role of Tim-3 blockade in NK cells function is controversial, as it can enhance the antitumor function of NK cells under certain conditions while having the opposite effect in other situations. Additionally, Tim-3 blockade can promote the reversal of macrophage polarization from the M2 phenotype to the M1 phenotype. Furthermore, Tim-3 blockade can inhibit tumor development by suppressing the proliferation and metastasis of tumor cells. In summary, increasing evidence has shown that Tim-3 in other cell types also plays a critical role in the efficacy of anti-Tim-3 therapy. Understanding the function of anti-Tim-3 therapy in non-T cells can help elucidate the diverse responses observed in clinical patients, leading to better development of relevant therapeutic strategies. This review aims to discuss the role of Tim-3 in the TME and emphasize the impact of Tim-3 blockade in the tumor immune microenvironment beyond T cells.

Targeting conserved TIM3+VISTA+ tumor-associated macrophages overcomes resistance to cancer immunotherapy

Despite the success of immunotherapy, overcoming immunoresistance in cancer remains challenging. We identified a unique niche of tumor-associated macrophages (TAMs), coexpressing T cell immunoglobulin and mucin domain-containing 3 (TIM3) and V-domain immunoglobulin suppressor of T cell activation (VISTA), that dominated human and mouse tumors resistant to most of the currently used immunotherapies. TIM3+VISTA+ TAMs were sustained by IL-4-enriching tumors with low (neo)antigenic and T cell-depleted features. TIM3+VISTA+ TAMs showed an anti-inflammatory and protumorigenic phenotype coupled with inability to sense type I interferon (IFN). This was established with cancer cells succumbing to immunogenic cell death (ICD). Dying cancer cells not only triggered autocrine type I IFNs but also exposed HMGB1/VISTA that engaged TIM3/VISTA on TAMs to suppress paracrine IFN-responses. Accordingly, TIM3/VISTA blockade synergized with paclitaxel, an ICD-inducing chemotherapy, to repolarize TIM3+VISTA+ TAMs to proinflammatory TAMs that killed cancer cells via tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) signaling. We propose targeting TIM3+VISTA+ TAMs to overcome immunoresistant tumors.

Impaired Proliferation of CD8+ T Cells Stimulated with Monocyte-Derived Dendritic Cells Previously Matured with Thapsigargin-Stimulated LAD2 Human Mast Cells

CD8+ T cells are essential for adaptive immunity against infection and tumors. Their ability to proliferate after stimulation is crucial to their functionality. Dendritic cells (DCs) are professional antigen-presenting cells that induce their proliferation. Here, we show that thapsigargin-induced LAD2 mast cell (MC) line-released products can impair the ability of monocyte-derived DCs to induce CD8+ T-cell proliferation and the generation of Th1 cytokine-producing T cells. We found that culture medium conditioned with LAD2 MCs previously stimulated with thapsigargin (thapsLAD2) induces maturation of DCs as determined by the maturation markers CD80, CD83, CD86, and HLA-DR. However, thapsLAD2-matured DCs produced no detectable TNFα or IL-12 during the maturation. In addition, although their surface expression of PD-L1 was comparable with the immature or TLR7/8-agonist (R848)-matured DCs, their TIM-3 expression was significantly higher than in immature DCs and even much higher than in R848-matured DCs. In addition, contrary to R848-matured DCs, the thapsLAD2-matured DCs only tended to induce enhanced proliferation of CD4+ T cells than immature DCs. For CD8+ T cells, this tendency was not even detected because thapsLAD2-matured and immature DCs comparably induced their proliferation, which contrasted with the significantly enhanced proliferation induced by R848-matured DCs. Furthermore, these differences were comparably recapitulated in the ability of the tested DCs to induce IFNγ- and IFNγ/TNFα-producing T cells. These findings show a novel mechanism of MC-mediated regulation of adaptive immune responses.

Inhibitory Checkpoint Receptor TIM-3 as a Regulator of the Functional Activity of Dendritic Cells

T-cell immunoglobulin and mucin domain 3 (TIM-3) belongs to the group of inhibitory checkpoint receptors and has traditionally been of interest in terms of its expression on activated CD4+ and CD8+ T cells. The treatment with TIM-3 inhibitors is considered as a promising strategy in cancer immunotherapy. The review focuses on new data on the expression of TIM-3 on dendritic cells (DCs) that play a key role in initiating the antigen-specific immune response and inducing effector CD8+ T cells. The main hypothesis is that TIM-3 is suggested to act as a negative regulator of DCs. Further studies on TIM-3-mediated DC regulation will improve the effectiveness of current strategies in the treatment of cancer using DCs and checkpoint molecule inhibitors, where the main targets can be not only T cells, but also TIM-3-expressing DCs.

XCR1: A promising prognostic marker that pinpoints targeted and immune-based therapy in hepatocellular carcinoma

Objectives

The lymphotactin receptor X-C motif chemokine receptor 1 (XCR1) is an essential member of the chemokine receptor family and is related to tumor development and progression. Nevertheless, further investigation is required to explore its expression patterns, prognostic values, and functions related to target or immune therapies in patients with hepatocellular carcinoma (HCC).

Materials and methods

The differential expression patterns of XCR1 and its prognostic influences were performed through The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) databases. Subsequently, immunohistochemistry (IHC) staining and univariate and multivariate Cox regressions were performed to validate the prognostic values in different subgroups. Furthermore, the potential roles of XCR1 in predicting target and immune therapeutic responses were also investigated.

Results

Increased expression level of XCR1 was associated with favorable overall survival (OS) and recurrence-free survival (RFS). Subgroup analysis revealed that a high expression level of XCR1 or positive immune cell proportion score (iCPS) were associated with favorable OS in the HCC patients with favorable tumor characteristics. In addition, the enhanced XCR1 expression was associated with the tumor environment scores, immune cell infiltration levels, and the expression levels of immune checkpoint genes. Further analysis revealed that improved expression of XCR1 was linked to better OS and RFS in HCC patients who received sorafenib.

Conclusion

This study identified that XCR1 is a valuable prognostic biomarker in the HCC population, especially in those with favorable tumor characteristics. The combination of iCPS status and BCLC status has a synergistic effect on stratifying patients' OS and RFS. Further analyses showed that XCR1 has the potential ability to predict treatment responses to sorafenib and immune-based therapies.

Dendritic Cells in Shaping Anti-Tumor T Cell Response

Among professional antigen-presenting cells, dendritic cells (DCs) orchestrate innate and adaptive immunity and play a pivotal role in anti-tumor immunity. DCs are a heterogeneous population with varying functions in the tumor microenvironment (TME). Tumor-associated DCs differentiate developmentally and functionally into three main subsets: conventional DCs (cDCs), plasmacytoid DCs (pDCs), and monocyte-derived DCs (MoDCs). There are two major subsets of cDCs in TME, cDC1 and cDC2. cDC1 is critical for cross-presenting tumor antigens to activate cytotoxic CD8+ T cells and is also required for priming earlier CD4+ T cells in certain solid tumors. cDC2 is vital for priming anti-tumor CD4+ T cells in multiple tumor models. pDC is a unique subset of DCs and produces type I IFN through TLR7 and TLR9. Studies have shown that pDCs are related to immunosuppression in the TME through the secretion of immunosuppressive cytokines and by promoting regulatory T cells. MoDCs differentiate separately from monocytes in response to inflammatory cues and infection. Also, MoDCs can cross-prime CD8+ T cells. In this review, we summarize the subsets and functions of DCs. We also discuss the role of different DC subsets in shaping T cell immunity in TME and targeting DCs for potential immunotherapeutic benefits against cancer.

DNA sensing of dendritic cells in cancer immunotherapy

Dendritic cells (DCs) are involved in the initiation and maintenance of immune responses against malignant cells by recognizing conserved pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) through pattern recognition receptors (PRRs). According to recent studies, tumor cell-derived DNA molecules act as DAMPs and are recognized by DNA sensors in DCs. Once identified by sensors in DCs, these DNA molecules trigger multiple signaling cascades to promote various cytokines secretion, including type I IFN, and then to induce DCs mediated antitumor immunity. As one of the potential attractive strategies for cancer therapy, various agonists targeting DNA sensors are extensively explored including the combination with other cancer immunotherapies or the direct usage as major components of cancer vaccines. Moreover, this review highlights different mechanisms through which tumor-derived DNA initiates DCs activation and the mechanisms through which the tumor microenvironment regulates DNA sensing of DCs to promote tumor immune escape. The contributions of chemotherapy, radiotherapy, and checkpoint inhibitors in tumor therapy to the DNA sensing of DCs are also discussed. Finally, recent clinical progress in tumor therapy utilizing agonist-targeted DNA sensors is summarized. Indeed, understanding more about DNA sensing in DCs will help to understand more about tumor immunotherapy and improve the efficacy of DC-targeted treatment in cancer.

Peristromal niches protect lung cancers from targeted therapies through a combined effect of multiple molecular mediators

Targeted therapies directed against oncogenic signaling addictions, such as inhibitors of ALK in ALK+ NSCLC often induce strong and durable clinical responses. However, they are not curative in metastatic cancers, as some tumor cells persist through therapy, eventually developing resistance. Therapy sensitivity can reflect not only cell-intrinsic mechanisms but also inputs from stromal microenvironment. Yet, the contribution of tumor stroma to therapeutic responses in vivo remains poorly defined. To address this gap of knowledge, we assessed the contribution of stroma-mediated resistance to therapeutic responses to the frontline ALK inhibitor alectinib in xenograft models of ALK+ NSCLC. We found that stroma-proximal tumor cells are partially protected against cytostatic effects of alectinib. This effect is observed not only in remission, but also during relapse, indicating the strong contribution of stroma-mediated resistance to both persistence and resistance. This therapy-protective effect of the stromal niche reflects a combined action of multiple mechanisms, including growth factors and extracellular matrix components. Consequently, despite improving alectinib responses, suppression of any individual resistance mechanism was insufficient to fully overcome the protective effect of stroma. Focusing on shared collateral sensitivity of persisters offered a superior therapeutic benefit, especially when using an antibody-drug conjugate with bystander effect to limit therapeutic escape. These findings indicate that stroma-mediated resistance might be the major contributor to both residual and progressing disease and highlight the limitation of focusing on suppressing a single resistance mechanism at a time.

Dendritic cells as orchestrators of anticancer immunity and immunotherapy

Dendritic cells (DCs) are a heterogeneous group of antigen-presenting innate immune cells that regulate adaptive immunity, including against cancer. Therefore, understanding the precise activities of DCs in tumours and patients with cancer is important. The classification of DC subsets has historically been based on ontogeny; however, single-cell analyses are now additionally revealing a diversity of functional states of DCs in cancer. DCs can promote the activation of potent antitumour T cells and immune responses via numerous mechanisms, although they can also be hijacked by tumour-mediated factors to contribute to immune tolerance and cancer progression. Consequently, DC activities are often key determinants of the efficacy of immunotherapies, including immune-checkpoint inhibitors. Potentiating the antitumour functions of DCs or using them as tools to orchestrate short-term and long-term anticancer immunity has immense but as-yet underexploited therapeutic potential. In this Review, we outline the nature and emerging complexity of DC states as well as their functions in regulating adaptive immunity across different cancer types. We also describe how DCs are required for the success of current immunotherapies and explore the inherent potential of targeting DCs for cancer therapy. We focus on novel insights on DCs derived from patients with different cancers, single-cell studies of DCs and their relevance to therapeutic strategies.

Beyond T cell exhaustion: TIM-3 regulation of myeloid cells

T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) is an important immune checkpoint molecule initially identified as a marker of IFN-γ-producing CD4+ and CD8+ T cells. Since then, our understanding of its role in immune responses has significantly expanded. Here, we review emerging evidence demonstrating unexpected roles for TIM-3 as a key regulator of myeloid cell function, in addition to recent work establishing TIM-3 as a delineator of terminal T cell exhaustion, thereby positioning TIM-3 at the interface between fatigued immune responses and reinvigoration. We share our perspective on the antagonism between TIM-3 and T cell stemness, discussing both cell-intrinsic and cell-extrinsic mechanisms underlying this relationship. Looking forward, we discuss approaches to decipher the underlying mechanisms by which TIM-3 regulates stemness, which has remarkable potential for the treatment of cancer, autoimmunity, and autoinflammation.

The paradoxical role of cytokines and chemokines at the tumor microenvironment: a comprehensive review

Tumor progression and eradication have long piqued the scientific community's interest. Recent discoveries about the role of chemokines and cytokines in these processes have fueled renewed interest in related research. These roles are frequently viewed as contentious due to their ability to both suppress and promote cancer progression. As a result, this review critically appraised existing literature to discuss the unique roles of cytokines and chemokines in the tumor microenvironment, as well as the existing challenges and future opportunities for exploiting these roles to develop novel and targeted treatments. While these modulatory molecules play an important role in tumor suppression via enhanced cancer-cell identification by cytotoxic effector cells and directly recruiting immunological effector cells and stromal cells in the TME, we observed that they also promote tumor proliferation. Many cytokines, including GM-CSF, IL-7, IL-12, IL-15, IL-18, and IL-21, have entered clinical trials for people with advanced cancer, while the FDA has approved interferon-alpha and IL-2. Nonetheless, low efficacy and dose-limiting toxicity limit these agents' full potential. Conversely, Chemokines have tremendous potential for increasing cancer immune-cell penetration of the tumor microenvironment and promoting beneficial immunological interactions. When chemokines are combined with cytokines, they activate lymphocytes, producing IL-2, CD80, and IL-12, all of which have a strong anticancer effect. This phenomenon opens the door to the development of effective anticancer combination therapies, such as therapies that can reverse cancer escape, and chemotaxis of immunosuppressive cells like Tregs, MDSCs, and TAMs.

Cytokine-armed dendritic cell progenitors for antigen-agnostic cancer immunotherapy

Dendritic cells (DCs) are antigen-presenting myeloid cells that regulate T cell activation, trafficking and function. Monocyte-derived DCs pulsed with tumor antigens have been tested extensively for therapeutic vaccination in cancer, with mixed clinical results. Here, we present a cell-therapy platform based on mouse or human DC progenitors (DCPs) engineered to produce two immunostimulatory cytokines, IL-12 and FLT3L. Cytokine-armed DCPs differentiated into conventional type-I DCs (cDC1) and suppressed tumor growth, including melanoma and autochthonous liver models, without the need for antigen loading or myeloablative host conditioning. Tumor response involved synergy between IL-12 and FLT3L and was associated with natural killer and T cell infiltration and activation, M1-like macrophage programming and ischemic tumor necrosis. Antitumor immunity was dependent on endogenous cDC1 expansion and interferon-γ signaling but did not require CD8+ T cell cytotoxicity. Cytokine-armed DCPs synergized effectively with anti-GD2 chimeric-antigen receptor (CAR) T cells in eradicating intracranial gliomas in mice, illustrating their potential in combination therapies.

Tumor Microenvironment Heterogeneity, Potential Therapeutic Avenues, and Emerging Therapies

OBJECTIVE

This review describes the comprehensive portrait of tumor microenvironment (TME). Additionally, we provided a panoramic perspective on the transformation and functions of the diverse constituents in TME, and the underlying mechanisms of drug resistance, beginning with the immune cells and metabolic dynamics within TME. Lastly, we summarized the most auspicious potential therapeutic strategies.

RESULTS

TME is a unique realm crafted by malignant cells to withstand the onslaught of endogenous and exogenous therapies. Recent research has revealed many small-molecule immunotherapies exhibiting auspicious outcomes in preclinical investigations. Furthermore, some pro-immune mechanisms have emerged as a potential avenue. With the advent of nanosystems and precision targeting, targeted therapy has now transcended the "comfort zone" erected by cancer cells within TME.

CONCLUSION

The ceaseless metamorphosis of TME fosters the intransigent resilience and proliferation of tumors. However, existing therapies have yet to surmount the formidable obstacles posed by TME. Therefore, scientists should investigate potential avenues for therapeutic intervention and design innovative pharmacological and clinical technologies.

Decoupled neoantigen cross-presentation by dendritic cells limits anti-tumor immunity against tumors with heterogeneous neoantigen expression

Cancer immunotherapies, in particular checkpoint blockade immunotherapy (CBT), can induce control of cancer growth, with a fraction of patients experiencing durable responses. However, the majority of patients currently do not respond to CBT and the molecular determinants of resistance have not been fully elucidated. Mounting clinical evidence suggests that the clonal status of neoantigens (NeoAg) impacts the anti-tumor T cell response. High intratumor heterogeneity (ITH), where the majority of NeoAgs are expressed subclonally, is correlated with poor clinical response to CBT and poor infiltration with tumor-reactive T cells. However, the mechanism by which ITH blunts tumor-reactive T cells is unclear. We developed a transplantable murine lung cancer model to characterize the immune response against a defined set of NeoAgs expressed either clonally or subclonally to model low or high ITH, respectively. Here we show that clonal expression of a weakly immunogenic NeoAg with a relatively strong NeoAg increased the immunogenicity of tumors with low but not high ITH. Mechanistically we determined that clonal NeoAg expression allowed cross-presenting dendritic cells to acquire and present both NeoAgs. Dual NeoAg presentation by dendritic cells was associated with a more mature DC phenotype and a higher stimulatory capacity. These data suggest that clonal NeoAg expression can induce more potent anti-tumor responses due to more stimulatory dendritic cell:T cell interactions. Therapeutic vaccination targeting subclonally expressed NeoAgs could be used to boost anti-tumor T cell responses.

Dendritic cell subsets in cancer immunity and tumor antigen sensing

Dendritic cells (DCs) exhibit a specialized antigen-presenting function and play crucial roles in both innate and adaptive immune responses. Due to their ability to cross-present tumor cell-associated antigens to naïve T cells, DCs are instrumental in the generation of specific T-cell-mediated antitumor effector responses in the control of tumor growth and tumor cell dissemination. Within an immunosuppressive tumor microenvironment, DC antitumor functions can, however, be severely impaired. In this review, we focus on the mechanisms of DC capture and activation by tumor cell antigens and the role of the tumor microenvironment in shaping DC functions, taking advantage of recent studies showing the phenotype acquisition, transcriptional state and functional programs revealed by scRNA-seq analysis. The therapeutic potential of DC-mediated tumor antigen sensing in priming antitumor immunity is also discussed.

Longitudinal analysis of DC subsets in patients with ovarian cancer: Implications for immunotherapy

Background

The use of circulating cDC1 to generate anti-cancer vaccines is among the most promising approaches to overcome the limited immunogenicity and clinical efficacy of monocyte-derived DC. However, the recurrent lymphopenia and the reduction of DC numbers and functionality in patients with cancer may represent an important limitation of such approach. In patients with ovarian cancer (OvC) that had received chemotherapy, we previously showed that cDC1 frequency and function were reduced.

Methods

We recruited healthy donors (HD, n=7) and patients with OvC at diagnosis and undergoing interval debulking surgery (IDS, n=6), primary debulking surgery (PDS, n=6) or at relapse (n=8). We characterized longitudinally phenotypic and functional properties of peripheral DC subsets by multiparametric flow cytometry.

Results

We show that the frequency of cDC1 and the total CD141+ DC capacity to take up antigen are not reduced at the diagnosis, while their TLR3 responsiveness is partially impaired in comparison with HD. Chemotherapy causes cDC1 depletion and increase in cDC2 frequency, but mainly in patients belonging to the PDS group, while in the IDS group both total lymphocytes and cDC1 are preserved. The capacity of total CD141+ DC and cDC2 to take up antigen is not impacted by chemotherapy, while the activation capacity upon Poly(I:C) (TLR3L) stimulation is further decreased.

Conclusions

Our study provides new information about the impact of chemotherapy on the immune system of patients with OvC and sheds a new light on the importance of considering timing with respect to chemotherapy when designing new vaccination strategies that aim at withdrawing or targeting specific DC subsets.

Once upon a prime: DCs shape cancer immunity

Cytotoxic CD8+ T cells are potent killers of diseased cells, but their functional capacity is often compromised in cancer. The quality of antitumor T cell immunity is determined during T cell priming in the lymph node and further influenced by the local microenvironment of the tumor. Increasing evidence indicates that dendritic cells (DCs) have the capacity to precisely regulate the functional quality of antitumor T cell responses in both locations. In this review, we discuss recent advances in our understanding of how distinct DC-derived signals influence CD8+ T cell differentiation and antitumor functions. Insight into the mechanisms of DC-mediated regulation of antitumor immunity could inspire the development of improved approaches to prevent and reverse T cell dysfunction in cancer.

Mature dendritic cells enriched in immunoregulatory molecules (mregDCs): A novel population in the tumour microenvironment and immunotherapy target

BACKGROUND

Dendritic cells (DCs) mediate divergent immune effects by activating T cells or negatively regulating the immune response to promote immune tolerance. They perform specific functions determined by their tissue distribution and maturation state. Traditionally, immature and semimature DCs were described to have immunosuppressive effects, leading to immune tolerance. Nonetheless, recent research has demonstrated that mature DCs can also suppress the immune response under certain circumstances.

MAIN BODY

Mature DCs enriched in immunoregulatory molecules (mregDCs) have emerged as a regulatory module across species and tumour types. Indeed, the distinct roles of mregDCs in tumour immunotherapy have sparked the interest of researchers in the field of single-cell omics. In particular, these regulatory cells were found to be associated with a positive response to immunotherapy and a favourable prognosis.

CONCLUSION

Here, we provide a general overview of the latest and most notable advances and recent findings regarding the basic features and complex roles of mregDCs in nonmalignant diseases and the tumour microenvironment. We also emphasise the important clinical implications of mregDCs in tumours.

MicroRNAs with Multiple Targets of Immune Checkpoints, as a Potential Sensitizer for Immune Checkpoint Inhibitors in Breast Cancer Treatment

Breast cancer is the most common cancer type and the leading cause of cancer-associated mortality in women worldwide. In recent years, immune checkpoint inhibitors (ICIs) have made significant progress in the treatment of breast cancer, yet there are still a considerable number of patients who are unable to gain lasting and ideal clinical benefits by immunotherapy alone, which leads to the development of a combination regimen as a novel research hotspot. Furthermore, one miRNA can target several checkpoint molecules, mimicking the therapeutic effect of a combined immune checkpoint blockade (ICB), which means that the miRNA therapy has been considered to increase the efficiency of ICIs. In this review, we summarized potential miRNA therapeutics candidates which can affect multiple targets of immune checkpoints in breast cancer with more therapeutic potential, and the obstacles to applying miRNA therapeutically through the analyses of the resources available from a drug target perspective. We also included the content of "too many targets for miRNA effect" (TMTME), combined with applying TargetScan database, to discuss adverse events. This review aims to ignite enthusiasm to explore the application of miRNAs with multiple targets of immune checkpoint molecules, in combination with ICIs for treating breast cancer.

Expression of Galectin-9-related immune checkpoint receptors in B-cell acute lymphoblastic leukemia

Objectives

Exhausted CD8+ T-cells over-express immune checkpoint receptors (ICRs), which interact with their ligands on malignant cells. However, some ICRs have been reported to be expressed on both T-cells and tumor cells, including V-domain immunoglobulin suppressor of T cell activation (VISTA), Galectin-9, and T-cell immunoglobulin mucin-3 (TIM-3). We aimed to evaluate the mRNA expression of VISTA, Galectin-9, and TIM-3 on CD8+ T-cells and leukemic cells in B-cell acute lymphoblastic leukemia (B-ALL).

Materials and Methods

Samples were obtained from 26 untreated B-ALL patients and 25 control subjects. CD8+ T-cells were isolated using Magnetic Activated Cell Sorting (MACS). Relative gene expression was then evaluated by qRT-PCR with specific primers for VISTA, Galectin-9, and TIM-3. Also, the mRNA expression profile and clinical data of 154 B-ALL patients were obtained from the TARGET.

Results

mRNA expression of Galectin-9 on CD8+ T-cells in B-ALL patients was significantly lower than those in the control group (P=0.043), while VISTA expression was not significantly different between the two study groups (P=0.259). Besides, TIM-3 expression was significantly higher in B-ALL patients than in the control group (P<0.001). Also, data obtained from TARGET showed that the relapse incidence was not significantly different between patients with high and low expression of Galectin-9 and TIM-3 in leukemic cells (P=0.360 and P=0.655, respectively).

Conclusion

Collectively, gene expression results suggest an important role for TIM-3, but not VISTA and Galectin-9, in B-ALL and it seems that TIM-3 could be a candidate for immune checkpoint therapy.

The role of CXCR3 and its ligands in cancer

Chemokines are a class of small cytokines or signaling proteins that are secreted by cells. Owing to their ability to induce directional chemotaxis of nearby responding cells, they are called chemotactic cytokines. Chemokines and chemokine receptors have now been shown to influence many cellular functions, including survival, adhesion, invasion, and proliferation, and regulate chemokine levels. Most malignant tumors express one or more chemokine receptors. The CXC subgroup of chemokine receptors, CXCR3, is mainly expressed on the surface of activated T cells, B cells, and natural killer cells, and plays an essential role in infection, autoimmune diseases, and tumor immunity by binding to specific receptors on target cell membranes to induce targeted migration and immune responses. It is vital to treat infections, autoimmune diseases, and tumors. CXCR3 and its ligands, CXCL9, CXCL10, and CXCL11, are closely associated with the development and progression of many tumors. With the elucidation of its mechanism of action, CXCR3 is expected to become a new indicator for evaluating the prognosis of patients with tumors and a new target for clinical tumor immunotherapy. This article reviews the significance and mechanism of action of the chemokine receptor CXCR3 and its specific ligands in tumor development.