CEACAM1 regulates TIM-3-mediated tolerance and exhaustion

Immune checkpoint inhibitor-based therapy for advanced clear cell renal cell carcinoma: A narrative review

The prognosis for advanced clear cell renal cell carcinoma (ccRCC) is not satisfactory, even though its treatment has evolved rapidly over the past 20 years. Systemic ccRCC treatment options mainly involve antiangiogenic therapy, immune checkpoint blockade, or a combination of these therapies, and as more clinical evidence becomes available, immune checkpoint inhibitors (ICIs) are increasingly dominant. Conventional ICIs lead to the restoration of T-cell activation and a reduction in T-cell depletion by specifically blocking programmed cell death 1 (PD-1), programmed cell death 1 ligand 1 (PD-L1) or cytotoxic T lymphocyte antigen 4 (CTLA-4), ultimately enhancing the antitumor immune response. There is no doubt that these therapies have achieved some clinical efficacy in the overall ccRCC population, but response rates and durability remain a great challenge. Therefore, novel immune checkpoints or new combination therapeutic strategies based on ICIs continue to be sought and developed. This review will provide a comprehensive overview of ICI-based therapeutic strategies in advanced ccRCC, including their mechanisms of action and the latest clinical evidence.

N6-Methyladenosine-Related Long Non-Coding RNAs Are Identified as a Potential Prognostic Biomarker for Lung Squamous Cell Carcinoma and Validated by Real-Time PCR

Currently, the precise mechanism by which N6-methyladenosine (m6A) modification of long non-coding RNAs (lncRNAs) promotes the occurrence and development of lung squamous cell carcinoma (LUSC) and influences tumor microenvironment (TME) remains unclear. Therefore, we studied the prognostic value of m6A-related lncRNAs and their relationship with TME in 495 LUSC samples from The Cancer Genome Atlas (TCGA) database. Pearson’s correlation and univariate Cox regression analysis identified 6 m6A-related lncRNAs with prognostic values for LUSC patients. LUSC patients were divided into two subgroups (clusters 1 and 2) using principal component analysis. The expression of PD-L1 was lower in tumor tissues and cluster 2 of LUSC patients. Cluster 2 of LUSC patients had a high immune score, stromal score, and unique immune cell infiltration. The focal adhesion kinase (FAK) pathway and cytokine receptor pathways are enriched in cluster 1. The m6A-related lncRNA prognostic markers (m6A-LPMs) were established using the least absolute shrinkage and selection operator (LASSO) Cox regression analysis. The risk score was calculated by 4 m6A-LPMs and associated with OS, TME, clinicopathological characteristics of LUSC patients. After adjusting for age, gender, and stage, the risk score was also an independent prognostic factor for LUSC patients. Real-time PCR results showed that the expression of 4 m6A-LPMs was consistent with our prediction results. Our study found that 4 m6A-LPMs (AC138035.1, AC243919.2, HORMAD2-AS1, and AL122125.1) are closely associated with LUSC prognosis, in future, they may as novel diagnostic biomarkers for LUSC and provide new immunotherapy targets for LUSC patients.

Tumor Immunology and Immunotherapy of Non-Small-Cell Lung Cancer

Historically, non-small-cell lung cancer (NSCLC) has been regarded as a nonimmunogenic tumor; however, recent studies have shown that NSCLCs are among the most responsive cancers to monoclonal antibody immune checkpoint inhibitors (ICIs). ICIs have dramatically improved clinical outcomes for a subset of patients (∼20%) with locally advanced and metastatic NSCLC, and they have also demonstrated promise as neoadjuvant therapy for early-stage resectable disease. Nevertheless, the majority of patients with NSCLC are refractory to ICIs for reasons that are poorly understood. Thus, major questions are: how do we initially identify the patients most likely to derive significant clinical benefit from these therapies; how can we increase the number of patients benefiting; what are the mechanisms of primary and acquired resistance to immune-based therapies; are there additional immune checkpoints besides PD-1/PD-L1 and CTLA-4 that can be targeted to provide greater clinical benefit to patients; and how do we best combine ICI therapy with surgery, radiotherapy, chemotherapy, and targeted therapy? To answer these questions, we need to deploy the latest technologies to study tumors and their microenvironment and how they interact with components of the innate and adaptive immune systems. There is also a need for new preclinical model systems to investigate the molecular mechanisms of resistance to treatment and identify novel therapeutic targets. Recent advances in technology are beginning to shed new light on the immune landscape of NSCLC that may uncover biomarkers of response and maximize the clinical benefit of immune-based therapies. Identification of the mechanisms of resistance should lead to the identification of novel targets and the generation of new therapeutic strategies that improve outcomes for a greater number of patients. In the sections below, we discuss the results of studies examining the immune microenvironment in NSCLC, summarize the clinical experience with immunotherapy for NSCLC, and review candidate biomarkers of response to these agents in NSCLC.

Novel Immune Checkpoints in Esophageal Cancer: From Biomarkers to Therapeutic Targets

Esophageal cancer ranks as the sixth most common cause of cancer death worldwide. Due to the limited efficacy of conventional therapeutic strategies, including surgery, chemotherapy, and radiotherapy, treatments are still far from satisfactory in terms of survival, prompting the search for novel treatment methods. Immune checkpoints play crucial roles in immune evasion mediated by tumor cells, and successful clinical outcomes have been achieved via blocking these pathways. However, only a small fraction of patients can benefit from current immune checkpoint inhibitors targeting programmed cell death ligand-1 (PD-L1) and cytotoxic T-lymphocyte-associated protein-4. Unfortunately, some patients show primary and/or acquired resistance to immune checkpoint inhibitors. Until now, novel immune checkpoint pathways have rarely been studied in esophageal cancer, and there is a great need for biomarkers to predict who will benefit from existing strategies. Herein, we primarily discuss the roles of new immune checkpoints as predictive biomarkers and therapeutic targets for esophageal cancer. In addition, we summarize the ongoing clinical trials and provide future research directions targeting these pathways.

Soluble T Cell Immunoglobulin and Mucin Domain-3 (sTIM-3) Predict Graft-Versus-Host Disease (GVHD) in Iranian Allogeneic Hematopoietic Stem Cell Transplantation

Background: T cell immunoglobulin and mucin domain-3 (TIM-3) is an immune-checkpoint molecule that is upregulated following allogeneic immune responses and could play an important role in the development and pathogenesis of graft-versus-host disease (GVHD). The soluble form of TIM-3 (sTIM-3) is increased following the upregulation of membranous TIM-3. Objectives: The aim of this study was to evaluate the association between plasma level of sTIM-3 and acute GVHD (aGVHD) incidence in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: Blood samples were collected from 42 allo-HSCT patients and 20 healthy individuals 2 weeks after allo-HSCT. The plasma level of sTIM-3 was measured using enzyme-linked immunosorbent assay (ELISA). The clinical and demographic data of patients were collected from the clinical documents. Data analysis was evaluated using student t-test and one-way ANOVA tests. P-values less than 0.05 were assumed statistically significant. Results: Among 18 (42.8%) patients with aGVHD symptoms, 10 (23.8%) had severe GVHD and 8 (19%) experienced mild GVHD. Plasma sTIM-3 levels at day +14 were significantly higher in patients who developed aGVHD compared to allo-HSCT patients without GVHD and also the healthy control individuals (P-value = 0.015 and < 0.001). Among the aGVHD patients, the sTIM-3 levels in those with severe GVHD were approximately 2.5 times higher than those with mild GVHD (P-value < 0.001). Conclusions: We have identified a high plasma level of sTIM-3 as a valuable biomarker in predicting the development of acute GVHD, especially severe aGVHD in allo-HSCT patients.

Solute carrier family 2 members 1 and 2 as prognostic biomarkers in hepatocellular carcinoma associated with immune infiltration

BACKGROUND

Metabolic reprogramming has been identified as a core hallmark of cancer. Solute carrier family 2 is a major glucose carrier family. It consists of 14 members, and we mainly study solute carrier family 2 member 1 (SLC2A1) and solute carrier family 2 member 2 (SLC2A2) here. SLC2A1, mainly existing in human erythrocytes, brain endothelial cells, and normal placenta, was found to be increased in hepatocellular carcinoma (HCC), while SLC2A2, the major transporter of the normal liver, was decreased in HCC.

AIM

To identify if SLC2A1 and SLC2A2 were associated with immune infiltration in addition to participating in the metabolic reprogramming in HCC.

METHODS

The expression levels of SLC2A1 and SLC2A2 were tested in HepG2 cells, HepG215 cells, and multiple databases. The clinical characteristics and survival data of SLC2A1 and SLC2A2 were examined by multiple databases. The correlation between SLC2A1 and SLC2A2 was analyzed by multiple databases. The functions and pathways in which SLC2A1, SLC2A2, and frequently altered neighbor genes were involved were discussed in String. Immune infiltration levels and immune marker genes associated with SLC2A1 and SLC2A2 were discussed from multiple databases.

RESULTS

The expression level of SLC2A1 was up-regulated, but the expression level of SLC2A2 was down-regulated in HepG2 cells, HepG215 cells, and liver cancer patients. The expression levels of SLC2A1 and SLC2A2 were related to tumor volume, grade, and stage in HCC. Interestingly, the expression levels of SLC2A1 and SLC2A2 were negatively correlated. Further, high SLC2A1 expression and low SLC2A2 expression were linked to poor overall survival and relapse-free survival. SLC2A1, SLC2A2, and frequently altered neighbor genes played a major role in the occurrence and development of tumors. Notably, SLC2A1 was positively correlated with tumor immune infiltration, while SLC2A2 was negatively correlated with tumor immune infiltration. Particularly, SLC2A2 methylation was positively correlated with lymphocytes.

CONCLUSION

SLC2A1 and SLC2A2 are independent therapeutic targets for HCC, and they are quintessential marker molecules for predicting and regulating the number and status of immune cells in HCC.

Human CEACAM1 N-domain dimerization is independent from glycan modifications

Carcinoembryonic cellular adhesion molecules (CEACAMs) serve diverse roles in cell signaling, proliferation, and survival and are made up of one or several immunoglobulin (Ig)-like ectodomains glycosylated in vivo. The physiological oligomeric state and how it contributes to protein function are central to understanding CEACAMs. Two putative dimer conformations involving different CEACAM1 N-terminal Ig-like domain (CCM1) protein faces (ABED and GFCC'C″) were identified from crystal structures. GFCC'C″ was identified as the dominant CCM1 solution dimer, but ambiguity regarding the effect of glycosylation on dimer formation calls its physiological relevance into question. We present the first crystal structure of minimally glycosylated CCM1 in the GFCC'C″ dimer conformation and characterization in solution by continuous-wave and double electron-electron resonance electron paramagnetic resonance spectroscopy. Our results suggest the GFCC'C″ dimer is dominant in solution with different levels of glycosylation, and structural conservation and co-evolved residues support that the GFCC'C″ dimer is conserved across CEACAMs.

Tim-3 mediates T cell trogocytosis to limit antitumor immunity

T cell immunoglobulin mucin domain-containing protein 3 (Tim-3) negatively regulates innate and adaptive immunity in cancer. To identify the mechanisms of Tim-3 in cancer immunity, we evaluated the effects of Tim-3 blockade in human and mouse melanoma. Here, we show that human programmed cell death 1-positive (PD-1+) Tim-3+CD8+ tumor-infiltrating lymphocytes (TILs) upregulate phosphatidylserine (PS), a receptor for Tim-3, and acquire cell surface myeloid markers from antigen-presenting cells (APCs) through transfer of membrane fragments called trogocytosis. Tim-3 blockade acted on Tim-3+ APCs in a PS-dependent fashion to disrupt the trogocytosis of activated tumor antigen-specific CD8+ T cells and PD-1+Tim-3+ CD8+ TILs isolated from patients with melanoma. Tim-3 and PD-1 blockades cooperated to disrupt trogocytosis of CD8+ TILs in 2 melanoma mouse models, decreasing tumor burden and prolonging survival. Deleting Tim-3 in dendritic cells but not in CD8+ T cells impeded the trogocytosis of CD8+ TILs in vivo. Trogocytosed CD8+ T cells presented tumor peptide-major histocompatibility complexes and became the target of fratricide T cell killing, which was reversed by Tim-3 blockade. Our findings have uncovered a mechanism Tim-3 uses to limit antitumor immunity.

Design and Evaluation of TIM-3-CD28 Checkpoint Fusion Proteins to Improve Anti-CD19 CAR T-Cell Function

Therapeutic targeting of inhibitory checkpoint molecules in combination with chimeric antigen receptor (CAR) T cells is currently investigated in a variety of clinical studies for treatment of hematologic and solid malignancies. However, the impact of co-inhibitory axes and their therapeutic implication remains understudied for the majority of acute leukemias due to their low immunogenicity/mutational load. The inhibitory exhaustion molecule TIM-3 is an important marker for the interaction of T cells with leukemic cells. Moreover, inhibitory signals from malignant cells could be transformed into stimulatory signals by synthetic fusion molecules with extracellular inhibitory receptors fused to an intracellular stimulatory domain. Here, we designed a variety of different TIM-3-CD28 fusion proteins to turn inhibitory signals derived by TIM-3 engagement into T-cell activation through CD28. In the absence of anti-CD19 CAR, two TIM-3-CD28 fusion receptors with large parts of CD28 showed strongest responses in terms of cytokine secretion and proliferation upon stimulation with anti-CD3 antibodies compared to controls. We then combined these two novel TIM-3-CD28 fusion proteins with first- and second-generation anti-CD19 CAR T cells and found that the fusion receptor can increase proliferation, activation, and cytotoxic capacity of conventional anti-CD19 CAR T cells. These additionally armed CAR T cells showed excellent effector function. In terms of safety considerations, the fusion receptors showed exclusively increased cytokine release, when the CAR target CD19 was present. We conclude that combining checkpoint fusion proteins with anti-CD19 CARs has the potential to increase T-cell proliferation capacity with the intention to overcome inhibitory signals during the response against malignant cells.

Tim-3 Expression Causes NK Cell Dysfunction in Type 2 Diabetes Patients

Type 2 diabetes mellitus (T2DM) is characterized by high blood glucose levels and chronic low-grade inflammation. It shows a strong association with obesity and immune dysfunction, which makes T2DM patients more susceptible to infectious diseases. NK cells play an important role in pathogen control and tumor surveillance. However, whether NK cell distribution and functional status are altered in T2DM is unclear. To address this issue, we compared surface receptor expression and cytokine production between peripheral blood NK cells from 90 T2DM patients and 62 age- and sex-matched healthy controls. We found a significantly lower frequency and absolute number of NK cells in patients than in controls. Interestingly, the expression of inhibitory receptor Tim-3 was significantly increased, while the expression of the activating receptor NKG2D was significantly decreased, in T2DM NK cells. Both TNF-α secretion and degranulation capacity (evidenced by CD107a expression) were dampened in NK cells from patients. The expression of Tim-3 on NK cells correlated positively with both HbA1c and fasting blood glucose levels and negatively with the percentage and absolute number of total NK cells and was associated with increased NK cell apoptosis. In addition, Tim-3 expression on NK cells negatively correlated with TNF-α production, which could be restored by blocking Galectin-9/Tim-3 pathway. Our results suggest that NK cell dysfunction secondary to augmented Tim-3 expression occurs in T2DM patients, which may partly explain their increased susceptibility to cancer and infectious disease.

Post-transplant Malignancies Show Reduced T-cell Abundance and Tertiary Lymphoid Structures as Correlates of Impaired Cancer Immunosurveillance

PURPOSE

An increased risk to develop cancer is one of the most challenging negative side effects of long-term immunosuppression in organ transplant recipients and impaired cancer immunosurveillance is assumed as underlying mechanism. This study aims to elucidate transplant-related changes in the tumor immune microenvironment (TME) of cancer.

EXPERIMENTAL DESIGN

Data from 123 organ transplant recipients (kidney, heart, lung, and liver) were compared with historic data from non-immunosuppressed patients. Digital image analysis of whole-section slides was used to assess abundance and spatial distribution of T cells and tertiary lymphoid structures (TLS) in the TME of 117 tumor samples. Expression of programmed cell death 1 ligand 1 (PD-L1) and human-leucocyte-antigen class I (HLA-I) was assessed on tissue microarrays.

RESULTS

We found a remarkably reduced immune infiltrate in the center tumor (CT) regions as well as the invasive margins (IM) of post-transplant cancers. These differences were more pronounced in the IM than in the CT and larger for CD8+ T cells than for CD3+ T cells. The Immune-score integrating results from CT and IM was also lower in transplant recipients. Density of TLS was lower in cancer samples of transplant recipients. The fraction of samples with PD-L1 expression was higher in controls whereas decreased expression of HLA-I was more common in transplant recipients.

CONCLUSIONS

Our study demonstrates the impact of immunosuppression on the TME and supports impaired cancer immunosurveillance as important cause of post-transplant cancer. Modern immunosuppressive protocols and cancer therapies should consider the distinct immune microenvironment of post-transplant malignancies.

The gut microbiota mediates protective immunity against tuberculosis via modulation of lncRNA

The gut-lung axis has been implicated as a potential therapeutic target in lung disorders. While increasing evidence suggests that gut microbiota plays a critical role in regulating host immunity and contributing to tuberculosis (TB) development and progression, the underlying mechanisms whereby gut microbiota may impact TB outcomes are not fully understood. Here, we found that broad-spectrum antibiotics treatment increased susceptibility to Mycobacterium tuberculosis (M. tuberculosis) infection and modulated pulmonary inflammatory responses in mouse M. tuberculosis infection model. We then identified a commensal gut bacteria-regulated lncRNA, termed lncRNA-CGB, which was down-regulated by dysbiosis of gut microbiota during TB infection. Furthermore, we found that Bacteroides fragilis (B. fragilis) was a direct regulator of lncRNA-CGB, and oral administration of B. fragilis enhanced expression of lncRNA-CGB and promoted anti-TB immunity. Genomic knock-out of lncRNA-CGB led to reduced IFN-γ expression and impaired anti-TB immunity, therefore leading to detrimental effects on M. tuberculosis infection. Mechanistically, lncRNA-CGB interacted with EZH2 and negatively regulated H3K27 tri-methylation (H3K27Me3) epigenetic programming, leading to enhanced IFN-γ expression. Thus, this work not only uncovered previously unrecognized importance of gut bacteria-lncRNA-EZH2-H3K27Me3 axis in conferring immune protection against TB but also identified a potential new paradigm to develop a microbiota-based treatment against TB and potentially other diseases.

The role of A Disintegrin and Metalloproteinase (ADAM)-10 in T helper cell biology

A Disintegrin and Metalloproteinases (ADAM)-10 is a member of a family of membrane-anchored proteinases that regulate a broad range of cellular functions with central roles within the immune system. This has spurred the interest to modulate ADAM activity therapeutically in immunological diseases. CD4 T helper (Th) cells are the key regulators of adaptive immune responses. Their development and function is strongly dependent on Notch, a key ADAM-10 substrate. However, Th cells rely on a variety of additional ADAM-10 substrates regulating their functional activity at multiple levels. The complexity of both, the ADAM substrate expression as well as the functional consequences of ADAM-mediated cleavage of the various substrates complicates the analysis of cell type specific effects. Here we provide an overview on the major ADAM-10 substrates relevant for CD4 T cell biology and discuss the potential effects of ADAM-mediated cleavage exemplified for a selection of important substrates.

Regulation of activated T cell survival in rheumatic autoimmune diseases

Adaptive immune responses rely on the proliferation of T lymphocytes able to recognize and eliminate pathogens. The magnitude and duration of the expansion of activated T cell clones are finely regulated to minimize immunopathology and avoid autoimmunity. In patients with rheumatic autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis, activated lymphocytes survive and exert effector functions for prolonged periods, defying the mechanisms that normally curb their capacities during acute and chronic infections. Here, we review the molecular mechanisms that limit the duration of immune responses in health and discuss the factors that alter such regulation in the setting of systemic lupus erythematosus and rheumatoid arthritis. We highlight defects that could contribute to the development and progression of autoimmune disease and describe how chronic inflammation can alter the regulation of activated lymphocyte survival, promoting its perpetuation. These concepts might contribute to the understanding of the mechanisms that underlie the chronicity of inflammation in the context of autoimmunity.

A novel and effective approach to generate germline-like monoclonal antibodies by integration of phage and mammalian cell display platforms

Phage display technology allows for rapid selection of antibodies from the large repertoire of human antibody fragments displayed on phages. However, antibody fragments should be converted to IgG for biological characterizations and affinity of antibodies obtained from phage display library is frequently not sufficient for efficient use in clinical settings. Here, we describe a new approach that combines phage and mammalian cell display, enabling simultaneous affinity screening of full-length IgG antibodies. Using this strategy, we successfully obtained a novel germline-like anti-TIM-3 monoclonal antibody named m101, which was revealed to be a potent anti-TIM-3 therapeutic monoclonal antibody via in vitro and in vivo experiments, indicating its effectiveness and power. Thus, this platform can help develop new monoclonal antibody therapeutics with high affinity and low immunogenicity.

Exploring the Mechanisms Underlying the Cardiotoxic Effects of Immune Checkpoint Inhibitor Therapies

Adaptive immune response modulation has taken a central position in cancer therapy in recent decades. Treatment with immune checkpoint inhibitors (ICIs) is now indicated in many cancer types with exceptional results. The two major inhibitory pathways involved are cytotoxic T-lymphocyte-associated protein 4 (CTLA4) and programmed cell death protein 1 (PD-1). Unfortunately, immune activation is not tumor-specific, and as a result, most patients will experience some form of adverse reaction. Most immune-related adverse events (IRAEs) involve the skin and gastrointestinal (GI) tract; however, any organ can be involved. Cardiotoxicity ranges from arrhythmias to life-threatening myocarditis with very high mortality rates. To date, most treatments of ICI cardiotoxicity include immune suppression, which is also not cardiac-specific and may result in hampering of tumor clearance. Understanding the mechanisms behind immune activation in the heart is crucial for the development of specific treatments. Histological data and other models have shown mainly CD4 and CD8 infiltration during ICI-induced cardiotoxicity. Inhibition of CTLA4 seems to result in the proliferation of more diverse T0cell populations, some of which with autoantigen recognition. Inhibition of PD-1 interaction with PD ligand 1/2 (PD-L1/PD-L2) results in release from inhibition of exhausted self-recognizing T cells. However, CTLA4, PD-1, and their ligands are expressed on a wide range of cells, indicating a much more intricate mechanism. This is further complicated by the identification of multiple co-stimulatory and co-inhibitory signals, as well as the association of myocarditis with antibody-driven myasthenia gravis and myositis IRAEs. In this review, we focus on the recent advances in unraveling the complexity of the mechanisms driving ICI cardiotoxicity and discuss novel therapeutic strategies for directly targeting specific underlying mechanisms to reduce IRAEs and improve outcomes.

Integrative multi-omics and drug response profiling of childhood acute lymphoblastic leukemia cell lines

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Although standard-of-care chemotherapeutics are sufficient for most ALL cases, there are subsets of patients with poor response who relapse in disease. The biology underlying differences between subtypes and their response to therapy has only partially been explained by genetic and transcriptomic profiling. Here, we perform comprehensive multi-omic analyses of 49 readily available childhood ALL cell lines, using proteomics, transcriptomics, and pharmacoproteomic characterization. We connect the molecular phenotypes with drug responses to 528 oncology drugs, identifying drug correlations as well as lineage-dependent correlations. We also identify the diacylglycerol-analog bryostatin-1 as a therapeutic candidate in the MEF2D-HNRNPUL1 fusion high-risk subtype, for which this drug activates pro-apoptotic ERK signaling associated with molecular mediators of pre-B cell negative selection. Our data is the foundation for the interactive online Functional Omics Resource of ALL (FORALL) with navigable proteomics, transcriptomics, and drug sensitivity profiles at https://proteomics.se/forall.

Childhood acute lymphoblastic leukemia is characterised by a range of genetic aberrations. Here, the authors use multi-omics profiling of ALL cell lines to connect molecular phenotypes and drug responses to provide an interactive resource of drug sensitivity.

Key Players of the Immunosuppressive Tumor Microenvironment and Emerging Therapeutic Strategies

The tumor microenvironment (TME) is a complex, dynamic battlefield for both immune cells and tumor cells. The advent of the immune checkpoint inhibitors (ICI) since 2011, such as the anti-cytotoxic T-lymphocyte associated protein (CTLA)-4 and anti-programmed cell death receptor (PD)-(L)1 antibodies, provided powerful weapons in the arsenal of cancer treatments, demonstrating unprecedented durable responses for patients with many types of advanced cancers. However, the response rate is generally low across tumor types and a substantial number of patients develop acquired resistance. These primary or acquired resistance are attributed to various immunosuppressive elements (soluble and cellular factors) and alternative immune checkpoints in the TME. Therefore, a better understanding of the TME is absolutely essential to develop therapeutic strategies to overcome resistance. Numerous clinical studies are underway using ICIs and additional agents that are tailored to the characteristics of the tumor or the TME. Some of the combination treatments are already approved by the Food and Drug Administration (FDA), such as platinum-doublet chemotherapy, tyrosine kinase inhibitor (TKI) -targeting vascular endothelial growth factor (VEGF) combined with anti-PD-(L)1 antibodies or immuno-immuno combinations (anti-CTLA-4 and anti-PD-1). In this review, we will discuss the key immunosuppressive cells, metabolites, cytokines or chemokines, and hypoxic conditions in the TME that contribute to tumor immune escape and the prospect of relevant clinical trials by targeting these elements in combination with ICIs.

Immunomodulatory Properties of Immune Checkpoint Inhibitors-More than Boosting T-Cell Responses?

The approval of immune checkpoint inhibitors (ICI) that serve to enhance effector T-cell anti-tumor responses has strongly improved success rates in the treatment of metastatic melanoma and other tumor types. The currently approved ICI constitute monoclonal antibodies blocking cytotoxic T-lymphocyte-associated protein (CTLA)-4 and anti-programmed cell death (PD)-1. By this, the T-cell-inhibitory CTLA-4/CD80/86 and PD-1/PD-1L/2L signaling axes are inhibited. This leads to sustained effector T-cell activity and circumvents the immune evasion of tumor cells, which frequently upregulate PD-L1 expression and modulate immune checkpoint molecule expression on leukocytes. As a result, profound clinical responses are observed in 40-60% of metastatic melanoma patients. Despite the pivotal role of T effector cells for triggering anti-tumor immunity, mounting evidence indicates that ICI efficacy may also be attributable to other cell types than T effector cells. In particular, emerging research has shown that ICI also impacts innate immune cells, such as myeloid cells, natural killer cells and innate lymphoid cells, which may amplify tumoricidal functions beyond triggering T effector cells, and thus improves clinical efficacy. Effects of ICI on non-T cells may additionally explain, in part, the character and extent of adverse effects associated with treatment. Deeper knowledge of these effects is required to further develop ICI treatment in terms of responsiveness of patients to treatment, to overcome resistance to ICI and to alleviate adverse effects. In this review we give an overview into the currently known immunomodulatory effects of ICI treatment in immune cell types other than the T cell compartment.

Future Prospects of Immunotherapy in Non-Small-Cell Lung Cancer Patients: Is There Hope in Other Immune Checkpoints Targeting Molecules?

Currently, one of the leading treatments for non-small-cell lung cancer is immunotherapy involving immune checkpoint inhibitors. These monoclonal antibodies restore the anti-tumour immune response altered by negative immune checkpoint interactions. The most commonly used immunotherapeutics in monotherapy are anti-PD-1 and anti-PD-L1 antibodies. The effectiveness of both groups of antibodies has been proven in many clinical trials, which have translated into positive immunotherapeutic registrations for cancer patients worldwide. These antibodies are generally well tolerated, and certain patients achieve durable responses. However, given the resistance of some patients to this form of therapy, along with its other drawbacks, such as adverse events, alternatives are constantly being sought. Specifically, new drugs targeting already known molecules are being tested, and new potential targets are being explored. The aim of this paper is to provide an overview of the latest developments in this area.

Phosphoantigen-stimulated γδ T cells suppress natural killer cell-responses to missing-self

γδ T cells stimulated by phosphoantigens (pAg) are potent effectors that secrete Th1 cytokines and kill tumor cells. Consequently, they are considered candidates for use in cancer immunotherapy. However, they have proven only moderately effective in several clinical trials. We studied the consequences of pAg-stimulated γδ T-cell interactions with Natural Killer (NK) cells and CD8+ T cells, major innate and adaptive effectors, respectively. We found that pAg-stimulated γδ T cells suppressed NK-cell responses to "missing-self" but had no effect on antigen-specific CD8+ T-cell responses. Extensive analysis of the secreted cytokines showed that pAg-stimulated γδ T cells had a pro-inflammatory profile. CMV-pp65-specific CD8+ T cells primed with pAg-stimulated γδ T cells showed little effect on responses to pp65-loaded target cells. By contrast, NK cells primed similarly with γδ T cells had impaired capacity to degranulate and produce IFNγ in response to HLA class I-deficient targets. This effect depended on BTN3A1 and required direct contact between NK cells and γδ T cells. γδ T cell-priming of NK cells also led to a downregulation of NKG2D and NKp44 on NK cells. Every NK-cell subset was affected by γδ T cell-mediated immunosuppression, but the strongest effect was on KIR+NKG2A- NK cells. We therefore report a previously unknown function for γδ T cells, as brakes of NK-cell responses to "missing-self". This provides a new perspective for optimizing the use of γδ T cells in cancer immunotherapy and for assessing their role in immune responses to pAg-producing pathogens.

Neutrophil Extracellular Traps in Cancer Therapy Resistance

Neutrophils and their products are increasingly recognized to have a key influence on cancer progression and response to therapy. Their involvement has been shown in nearly every aspect of cancer pathophysiology with growing evidence now supporting their role in resistance to a variety of cancer therapies. Recently, the role of neutrophils in cancer progression and therapy resistance has been further complicated with the discovery of neutrophil extracellular traps (NETs). NETs are web-like structures of chromatin decorated with a variety of microbicidal proteins. They are released by neutrophils in a process called NETosis. NET-dependent mechanisms of cancer pathology are beginning to be appreciated, particularly with respect to tumor response to chemo-, immuno-, and radiation therapy. Several studies support the functional role of NETs in cancer therapy resistance, involving T-cell exhaustion, drug detoxification, angiogenesis, the epithelial-to-mesenchymal transition, and extracellular matrix remodeling mechanisms, among others. Given this, new and promising data suggests NETs provide a microenvironment conducive to limited therapeutic response across a variety of neoplasms. As such, this paper aims to give a comprehensive overview of evidence on NETs in cancer therapy resistance with a focus on clinical applicability.

Next generation of immune checkpoint molecules in maternal-fetal immunity

Successful pregnancy is a unique situation requires the maternal immune system to recognize and tolerate a semi-identical fetus and allow normal invasion of trophoblast cells. Although efforts have been made, the deep mechanisms of the maternal-fetal crosstalk have not yet been fully deciphered. Immune checkpoint molecules (ICMs) are a group of negative modulators of the immune response that avoid immune damage. They have been extensively studied in the fields of oncology and transplantation, while the latest evidence suggests that they are closely associated with pregnancy outcomes via multiple inhibitory mechanisms. Although studies have mostly demonstrated the regulatory role of the well-known PD-1, CTLA-4 at the maternal-fetal interface, what is unique about the newly discovered multiple ICMs remains a mystery. Here, we review the latest knowledge on ICMs, focusing on the first generation of checkpoints (PD-1, CTLA-4) and the next generation (Tim-3, Tigit, Lag-3, VISTA) highlighting their immunoregulatory roles in maternal-fetal tolerance and decidual vascular remodeling, and their involvement in pathological pregnancies. The content covers three aspects: the characteristics they possess, the dynamic expression profile of their expression at the maternal-fetal interface, and their involvement in pathological pregnancy. In immunotherapy strategies for pregnancy complications, upregulation of immune checkpoints may play a role. Meanwhile, the impact on pregnancy outcomes when using ICMs in clinical cancer treatment during pregnancy is a topic worth exploring. These may serve as a guide for future basic research and clinical applications of maternal-fetal immunity.

Photophosphatidylserine Guides Natural Killer Cell Photoimmunotherapy via Tim-3

Natural killer (NK) cells, in addition to their cytotoxicity function, harbor prominent cytokine production capabilities and contribute to regulating autoimmune responses. T-cell immunoglobulin and mucin domain containing protein-3 (Tim-3) is one of the inhibitory receptors on NK cells and a promising immune checkpoint target. We recently found that phosphatidylserine (PS) binding to Tim-3 can suppress NK cell activation. Therefore, based on the therapeutic potential of Tim-3 in NK-cell-mediated diseases, we developed a photoswitchable ligand of Tim-3, termed photophosphatidylserine (phoPS), that mimics the effects of PS. Upon 365 or 455 nm light irradiation, the isomer of phoPS cyclically conversed the cis/trans configuration, resulting in an active/inactive Tim-3 ligand, thus modulating the function of NK cells in vitro and in vivo. We also demonstrated that reversible phoPS enabled optical control of acute hepatitis. Together, phoPS may be an appealing tool for autoimmune diseases and cytokine storms in the future.

Immunotherapy for Colorectal Cancer: Mechanisms and Predictive Biomarkers

Simple Summary

Late-stage colorectal cancer treatment often involves chemotherapy and radiation that can cause dose-limiting toxicity, and therefore there is great interest in developing targeted therapies for this disease. Immunotherapy is a targeted therapy that uses peptides, cells, antibodies, viruses, or small molecules to engage or train the immune system to kill cancer. Here, we discuss the preclinical and clinical development of immunotherapy for treatment of colorectal cancer and provide an overview of predictive biomarkers for such treatments. We also consider open questions including optimal combination treatments and sensitization of colorectal cancer patients with proficient mismatch repair enzymes.

Abstract

Though early-stage colorectal cancer has a high 5 year survival rate of 65–92% depending on the specific stage, this probability drops to 13% after the cancer metastasizes. Frontline treatments for colorectal cancer such as chemotherapy and radiation often produce dose-limiting toxicities in patients and acquired resistance in cancer cells. Additional targeted treatments are needed to improve patient outcomes and quality of life. Immunotherapy involves treatment with peptides, cells, antibodies, viruses, or small molecules to engage or train the immune system to kill cancer cells. Preclinical and clinical investigations of immunotherapy for treatment of colorectal cancer including immune checkpoint blockade, adoptive cell therapy, monoclonal antibodies, oncolytic viruses, anti-cancer vaccines, and immune system modulators have been promising, but demonstrate limitations for patients with proficient mismatch repair enzymes. In this review, we discuss preclinical and clinical studies investigating immunotherapy for treatment of colorectal cancer and predictive biomarkers for response to these treatments. We also consider open questions including optimal combination treatments to maximize efficacy, minimize toxicity, and prevent acquired resistance and approaches to sensitize mismatch repair-proficient patients to immunotherapy.

Effects of immune checkpoint blockade on antigen-specific CD8+ T cells for use in adoptive cellular therapy

BACKGROUND

Adoptive T cell therapies have been successfully used as prophylaxis or treatment for immunocompromised patients at risk of viral infections or advanced cancers. Unfortunately, for some refractory cancers, they have failed. To overcome this, checkpoint inhibitors have shown to rescue immune anti-tumor responses. We hypothesized that in-vitro checkpoint blockade during T-cell stimulation and expansion with mRNA-pulsed dendritic cells may enhance the activity of antigen-specific T-cells and improve the efficacy of ACT platforms.

METHODS

Human PBMCs were isolated from CMV-seropositive donors to generate DCs. These were pulsed with CMVpp65-mRNA to educate T-cells in co-culture for 15-days. Three checkpoint blockade conditions were evaluated (anti-PD1, anti-Tim3 and anti-PD1+Tim3). IL-2 and antibodies blockades were added every 3 days. Immunophenotyping was performed on Day-0 and Day-15. Polyfunctional antigen-specific responses were evaluated upon rechallenge with CMVpp65 peptides.

RESULTS

CMVpp65 activated CD8+ T cells upregulate Lag3 and Tim3 (p= <0.0001). Tim3 antibody blockade alone or in combination led to a significant upregulation of Lag3 expression on CD8+pp65Tetramer+ central memory, effector memory, and TEMRA T-cells. This latter T-cell subset uniquely maintain double-positive Tim3/Lag3 expression after checkpoint blockade. In contrast, PD1 blockade had minimal effects on Tim3 or Lag3 expression. In addition, IFN-g secretion was reduced in T-cells treated with Tim3 blockade in a dose-dependent manner (p=0.004).

CONCLUSION

In this study, we have identified a potential activating component of Tim3 and linkage between Tim3 and Lag3 signaling upon blocking Tim3 axis during T cell/antigen presenting cell interactions that should be considered when targeting immune checkpoints for clinical use. This article is protected by copyright. All rights reserved.

Immune checkpoint blockade in HIV

Antiretroviral therapy (ART) has dramatically improved life expectancy for people with HIV (PWH) and helps to restore immune function but is not curative and must be taken lifelong. Achieving long term control of HIV in the absence of ART will likely require potent T cell function, but chronic HIV infection is associated with immune exhaustion that persists even on ART. This is driven by elevated expression of immune checkpoints that provide negative signalling to T cells. In individuals with cancer, immune checkpoint blockade augments tumour-directed T-cell responses resulting in significant clinical cures. There is therefore high interest if ICB can contribute to HIV cure or remission by reversing HIV-latency and/or drive recovery of HIV-specific T-cells. We here review recent evidence on the role of immune checkpoints in persistent HIV infection and discuss the potential for employing immune checkpoint blockade as a therapeutic approach to target HIV persistence on ART.

An Emerging Role of TIM3 Expression on T Cells in Chronic Kidney Inflammation

T cell immunoglobulin domain and mucin domain 3 (TIM3) was initially identified as an inhibitory molecule on IFNγ-producing T cells. Further research discovered the broad expression of TIM3 on different immune cells binding to multiple ligands. Apart from its suppressive effects on the Th1 cells, recent compelling experiments highlighted the indispensable role of TIM3 in the myeloid cell-mediated inflammatory response, supporting that TIM3 exerts pleiotropic effects on both adaptive and innate immune cells in a context-dependent manner. A large number of studies have been conducted on TIM3 biology in the disease settings of infection, cancer, and autoimmunity. However, there is a lack of clinical evidence to closely evaluate the role of T cell-expressing TIM3 in the pathogenesis of chronic kidney disease (CKD). Here, we reported an intriguing case of Mycobacterium tuberculosis (Mtb) infection that was characterized by persistent overexpression of TIM3 on circulating T cells and ongoing kidney tubulointerstitial inflammation for a period of 12 months. In this case, multiple histopathological biopsies revealed a massive accumulation of recruited T cells and macrophages in the enlarged kidney and liver. After standard anti-Mtb treatment, repeated renal biopsy identified a dramatic remission of the infiltrated immune cells in the tubulointerstitial compartment. This is the first clinical report to reveal a time-course expression of TIM3 on the T cells, which is pathologically associated with the progression of severe kidney inflammation in a non-autoimmunity setting. Based on this case, we summarize the recent findings on TIM3 biology and propose a novel model of CKD progression due to the aberrant crosstalk among immune cells.

KIM-1/TIM-1 is a Receptor for SARS-CoV-2 in Lung and Kidney

SARS-CoV-2 precipitates respiratory distress by infection of airway epithelial cells and is often accompanied by acute kidney injury. We report that Kidney Injury Molecule-1/T cell immunoglobulin mucin domain 1 (KIM-1/TIM-1) is expressed in lung and kidney epithelial cells in COVID-19 patients and is a receptor for SARS-CoV-2. Human and mouse lung and kidney epithelial cells express KIM-1 and endocytose nanoparticles displaying the SARS-CoV-2 spike protein (virosomes). Uptake was inhibited by anti-KIM-1 antibodies and TW-37, a newly discovered inhibitor of KIM-1-mediated endocytosis. Enhanced KIM-1 expression by human kidney tubuloids increased uptake of virosomes. KIM-1 binds to the SARS-CoV-2 Spike protein in vitro . KIM-1 expressing cells, not expressing angiotensin-converting enzyme 2 (ACE2), are permissive to SARS-CoV-2 infection. Thus, KIM-1 is an alternative receptor to ACE2 for SARS-CoV-2. KIM-1 targeted therapeutics may prevent and/or treat COVID-19.

Inhibitory pattern recognition receptors

Pathogen- and damage-associated molecular patterns are sensed by the immune system's pattern recognition receptors (PRRs) upon contact with a microbe or damaged tissue. In situations such as contact with commensals or during physiological cell death, the immune system should not respond to these patterns. Hence, immune responses need to be context dependent, but it is not clear how context for molecular pattern recognition is provided. We discuss inhibitory receptors as potential counterparts to activating pattern recognition receptors. We propose a group of inhibitory pattern recognition receptors (iPRRs) that recognize endogenous and microbial patterns associated with danger, homeostasis, or both. We propose that recognition of molecular patterns by iPRRs provides context, helps mediate tolerance to microbes, and helps balance responses to danger signals.

Enhancing immunotherapy in cancer by targeting emerging immunomodulatory pathways

The discovery and clinical implementation of immune-checkpoint inhibitors (ICIs) targeting CTLA4, PD-1 and PD-L1 has revolutionized the treatment of cancer, as recognized by the 2018 Nobel Prize for Medicine and Physiology. This groundbreaking new approach has improved the outcomes of patients with various forms of advanced-stage cancer; however, the majority of patients receiving these therapies, even in combination, do not derive clinical benefit. Further development of agents targeting additional immune checkpoints, co-stimulatory receptors and/or co-inhibitory receptors that control T cell function is therefore critical. In this Review, we discuss the translational potential and clinical development of agents targeting both co-stimulatory and co-inhibitory T cell receptors. Specifically, we describe their mechanisms of action, and provide an overview of ongoing clinical trials involving novel ICIs including those targeting LAG3, TIM3, TIGIT and BTLA as well as agonists of the co-stimulatory receptors GITR, OX40, 41BB and ICOS. We also discuss several additional approaches, such as harnessing T cell metabolism, in particular via adenosine signalling, inhibition of IDO1, and targeting changes in glucose and fatty acid metabolism. We conclude that further efforts are needed to optimize the timing of combination ICI approaches and, most importantly, to individualize immunotherapy based on both patient-specific and tumour-specific characteristics.

Single-cell RNA sequencing reveals evolution of immune landscape during glioblastoma progression

Glioblastoma (GBM) is an incurable primary malignant brain cancer hallmarked with a substantial protumorigenic immune component. Knowledge of the GBM immune microenvironment during tumor evolution and standard of care treatments is limited. Using single-cell transcriptomics and flow cytometry, we unveiled large-scale comprehensive longitudinal changes in immune cell composition throughout tumor progression in an epidermal growth factor receptor-driven genetic mouse GBM model. We identified subsets of proinflammatory microglia in developing GBMs and anti-inflammatory macrophages and protumorigenic myeloid-derived suppressors cells in end-stage tumors, an evolution that parallels breakdown of the blood-brain barrier and extensive growth of epidermal growth factor receptor⁺ GBM cells. A similar relationship was found between microglia and macrophages in patient biopsies of low-grade glioma and GBM. Temozolomide decreased the accumulation of myeloid-derived suppressor cells, whereas concomitant temozolomide irradiation increased intratumoral GranzymeB⁺ CD8⁺T cells but also increased CD4⁺ regulatory T cells. These results provide a comprehensive and unbiased immune cellular landscape and its evolutionary changes during GBM progression.

TIM3+ cells in gastric cancer: clinical correlates and association with immune context

BACKGROUND

T cell immunoglobulin and mucin domain-containing protein 3 (TIM3) is a crucial immune checkpoint and is considered as an emerging target for cancer treatment. However, the clinical significance and immune-related role of TIM3⁺ cells in gastric cancer remain unknown. This study aimed to investigate the clinical significance of tumour-infiltrating TIM3⁺ cells and their association with immune contexture in gastric cancer.

METHODS

This study enrolled three cohorts, including 436 tumour tissue microarray specimens and 58 fresh tumour tissues of gastric cancer patients from Zhongshan Hospital, and 330 transcriptional data from The Cancer Genome Atlas. TIM3⁺ cells and their association with CD8⁺ T cells were evaluated by immunohistochemistry and flow cytometry analyses. Kaplan-Meier curves, Cox model and interaction test were performed to assess clinical outcomes.

RESULTS

Tumour-infiltrating TIM3⁺ cells' high subgroups experienced poorer overall survival and disease-free survival and predicted inferior therapeutic responsiveness to fluorouracil-based adjuvant chemotherapy. TIM3 indicated CD8⁺ T cell dysfunction, which impeded chemotherapeutic responsiveness. Besides, HAVCR2 messenger RNA expression was associated with specific molecular characteristics.

CONCLUSIONS

The abundance of tumour-infiltrating TIM3⁺ cells could identify an immunoevasive subtype gastric cancer with CD8⁺ T cell dysfunction, suggesting that TIM3 might serve as a promising target for immunotherapy in gastric cancer.

Expression of Immune Checkpoints in Malignant Tumors: Therapy Targets and Biomarkers for the Gastric Cancer Prognosis

To increase the effectiveness of anticancer therapy based on immune checkpoint (IC) inhibition, some ICs are being investigated in addition to those used in clinic. We reviewed data on the relationship between PD-L1, B7-H3, B7-H4, IDO1, Galectin-3 and -9, CEACAM1, CD155, Siglec-15 and ADAM17 expression with cancer development in complex with the results of clinical trials on their inhibition. Increased expression of the most studied ICs—PD-L1, B7-H3, and B7-H4—is associated with poor survival; their inhibition is clinically significant. Expression of IDO1, CD155, and ADAM17 is also associated with poor survival, including gastric cancer (GC). The available data indicate that CD155 and ADAM17 are promising targets for immune therapy. However, the clinical trials of anti-IDO1 antibodies have been unsatisfactory. Expression of Galectin-3 and -9, CEACAM1 and Siglec-15 demonstrates a contradictory relationship with patient survival. The lack of satisfactory results of these IC inhibitor clinical trials additionally indicates the complex nature of their functioning. In conclusion, in many cases it is important to analyze the expression of other participants of the immune response besides target IC. The PD-L1, B7-H3, B7-H4, IDO1 and ADAM17 may be considered as candidates for prognosis markers for GC patient survival.

Immune Regulatory Processes of the Tumor Microenvironment under Malignant Conditions

The tumor microenvironment (TME) is a critical regulator of tumor growth, progression, and metastasis. Since immune cells represent a large fraction of the TME, they play a key role in mediating pro- and anti-tumor immune responses. Immune escape, which suppresses anti-tumor immunity, enables tumor cells to maintain their proliferation and growth. Numerous mechanisms, which have been intensively studied in recent years, are involved in this process and based on these findings, novel immunotherapies have been successfully developed. Here, we review the composition of the TME and the mechanisms by which immune evasive processes are regulated. In detail, we describe membrane-bound and soluble factors, their regulation, and their impact on immune cell activation in the TME. Furthermore, we give an overview of the tumor/antigen presentation and how it is influenced under malignant conditions. Finally, we summarize novel TME-targeting agents, which are already in clinical trials for different tumor entities.

Pushing Past the Blockade: Advancements in T Cell-Based Cancer Immunotherapies

Successful cancer immunotherapies rely on a replete and functional immune compartment. Within the immune compartment, T cells are often the effector arm of immune-based strategies due to their potent cytotoxic capabilities. However, many tumors have evolved a variety of mechanisms to evade T cell-mediated killing. Thus, while many T cell-based immunotherapies, such as immune checkpoint inhibition (ICI) and chimeric antigen receptor (CAR) T cells, have achieved considerable success in some solid cancers and hematological malignancies, these therapies often fail in solid tumors due to tumor-imposed T cell dysfunctions. These dysfunctional mechanisms broadly include reduced T cell access into and identification of tumors, as well as an overall immunosuppressive tumor microenvironment that elicits T cell exhaustion. Therefore, novel, rational approaches are necessary to overcome the barriers to T cell function elicited by solid tumors. In this review, we will provide an overview of conventional immunotherapeutic strategies and the various barriers to T cell anti-tumor function encountered in solid tumors that lead to resistance. We will also explore a sampling of emerging strategies specifically aimed to bypass these tumor-imposed boundaries to T cell-based immunotherapies.

SOX10 requirement for melanoma tumor growth is due, in part, to immune-mediated effects

Developmental factors may regulate the expression of immune modulatory proteins in cancer, linking embryonic development and cancer cell immune evasion. This is particularly relevant in melanoma because immune checkpoint inhibitors are commonly used in the clinic. SRY-box transcription factor 10 (SOX10) mediates neural crest development and is required for melanoma cell growth. In this study, we investigate immune-related targets of SOX10 and observe positive regulation of herpesvirus entry mediator (HVEM) and carcinoembryonic-antigen cell-adhesion molecule 1 (CEACAM1). Sox10 knockout reduces tumor growth in vivo, and this effect is exacerbated in immune-competent models. Modulation of CEACAM1 expression but not HVEM elicits modest effects on tumor growth. Importantly, Sox10 knockout effects on tumor growth are dependent, in part, on CD8+ T cells. Extending this analysis to samples from patients with cutaneous melanoma, we observe a negative correlation with SOX10 and immune-related pathways. These data demonstrate a role for SOX10 in regulating immune checkpoint protein expression and anti-tumor immunity in melanoma.

Switch receptor T3/28 improves long-term persistence and antitumor efficacy of CAR-T cells

Background

Chimeric antigen receptor (CAR) T cells have been successfully used in tumor immunotherapy due to their strong antitumor responses, especially in hematological malignancies such as B cell acute lymphoid leukemia. However, on-target off-tumor toxicity and poor persistence severely limit the clinical application of CAR-T cell therapy.

Methods

T-cell immunoglobulin mucin domain molecule 3 (TIM-3) was used to develop a second-generation 41BB CD19 CAR linked with a T3/28 chimera, in which truncated extracellular TIM-3 was fused with the CD28 transmembrane and cytoplasmic domains. The efficacy of T3/28 CAR-T cells was evaluated in vitro and in vivo.

Results

We demonstrated that the switch receptor T3/28 preserved the T_CM phenotype, improved proliferative capacity, and reduced exhaustion of CAR-T cells, resulting in superior in vitro and in vivo antitumor activity in B lymphoma. Importantly, the switch receptor T3/28 substantially prolonged the persistence of CAR-T cells, and the interleukin-21/Stat3 axis probably contributed to the enhanced cytotoxicity of T3/28 CAR-T cells.

Conclusion

Overall, the T3/28 chimera significantly prolonged the persistence of CAR-T cells, and T3/28 CAR-T cells possessed potent antitumor activity in mice, shedding new light on potential improvements in adoptive T cell therapies.

Biointerfacing Antagonizing T-Cell Inhibitory Nanoparticles Potentiate Hepatocellular Carcinoma Checkpoint Blockade Therapy

Hepatocellular carcinoma (HCC) is one of the most fatal malignancies with few effective treatment options all around the world. The efficacy of the arisen immune checkpoint therapy is still uncertain due to local immunosuppression. In order to further overcome T cell suppression in the tumor immune microenvironment while promoting the immune response of antigen-presenting cells, a biointerfacing antagonizing T-cell inhibitory nanoparticles (BAT NPs) has been developed by cloaking platelet membrane on the PLGA microsphere surface to load T-cell immunoglobulin domain and mucin domain-3 antibodies (anti-TIM-3) as well as PD-L1. Notably, in addition to activating the proliferation and migration of T cells, the contained anti-TIM-3 can cooperate with PD-L1 checkpoint blockade to exert therapeutic effects. Furthermore, the components of BAT NPs like anti-TIM-3 and platelet can act together for collagen deposition in tumor starvation treatment. Thus, a novel targeting therapeutic strategy that can effectively reverse the immune-inhibiting microenvironment is effectively applied to PD-L1 checkpoint combination therapy. Such therapeutic effect can subsequently activate the effector T lymphocytes and antigen presentation of dendritic cells as well as the polarization of M1-type macrophages. Last, the study presented the synergistic effect of immune therapeutic adjuvants and BAT NPs components in achieving tumor inhibition and prolonging tumor-burden survival.

Current Progress and Future Perspectives of Immune Checkpoint in Cancer and Infectious Diseases

The inhibitory regulators, known as immune checkpoints, prevent overreaction of the immune system, avoid normal tissue damage, and maintain immune homeostasis during the antimicrobial or antiviral immune response. Unfortunately, cancer cells can mimic the ligands of immune checkpoints to evade immune surveillance. Application of immune checkpoint blockade can help dampen the ligands expressed on cancer cells, reverse the exhaustion status of effector T cells, and reinvigorate the antitumor function. Here, we briefly introduce the structure, expression, signaling pathway, and targeted drugs of several inhibitory immune checkpoints (PD-1/PD-L1, CTLA-4, TIM-3, LAG-3, VISTA, and IDO1). And we summarize the application of immune checkpoint inhibitors in tumors, such as single agent and combination therapy and adverse reactions. At the same time, we further discussed the correlation between immune checkpoints and microorganisms and the role of immune checkpoints in microbial-infection diseases. This review focused on the current knowledge about the role of the immune checkpoints will help in applying immune checkpoints for clinical therapy of cancer and other diseases.

Immune Checkpoints and Innate Lymphoid Cells-New Avenues for Cancer Immunotherapy

Immune checkpoints (IC) are broadly characterized as inhibitory pathways that tightly regulate the activation of the immune system. These molecular "brakes" are centrally involved in the maintenance of immune self-tolerance and represent a key mechanism in avoiding autoimmunity and tissue destruction. Antibody-based therapies target these inhibitory molecules on T cells to improve their cytotoxic function, with unprecedented clinical efficacies for a number of malignancies. Many of these ICs are also expressed on innate lymphoid cells (ILC), drawing interest from the field to understand their function, impact for anti-tumor immunity and potential for immunotherapy. In this review, we highlight ILC specificities at different tissue sites and their migration potential upon inflammatory challenge. We further summarize the current understanding of IC molecules on ILC and discuss potential strategies for ILC modulation as part of a greater anti-cancer armamentarium.

Regulation of Tim-3 function by binding to phosphatidylserine

Tim-3 is a transmembrane protein that is highly expressed on subsets of chronically stimulated CD4+ helper and CD8+ cytotoxic T cells, with more transient expression during acute activation and infection. Tim-3 is also constitutively expressed by multiple types of myeloid cells. Like other TIM family members, Tim-3 can bind to phosphatidylserine displayed by apoptotic cells, and this interaction has been shown to mediate uptake of such cells by dendritic cells and cross-presentation of antigens to CD8+ T cells. In contrast, how the recognition of PS by Tim-3 might regulate the function of Tim-3+ T cells is not known. In their recent paper, Lemmon and colleagues demonstrate for the first time that recognition of PS by Tim-3 leads to enhanced T cell activation.

Novel immune targets for the treatment of triple-negative breast cancer

INTRODUCTION

To overcome mechanisms of primary and secondary resistance to the anti-tumor immune response, novel targets such as ICOS, LAG3, and TIM3 are currently being explored at preclinical and early-phase clinical levels.

AREAS COVERED

This article examines the landscape of the immune therapeutics investigated in early-phase clinical trials for TNBC. Preclinical rationale is provided for each immune target, predominant expression, and function. Clinical implications and preliminary available trial results are discussed and finally, we reflect on aspects of future expectations and challenges in this field.

EXPERT OPINION

Several immune strategies have been investigated in TNBC, including co-inhibitory molecules beyond PD1-PD-L1 axis, co-stimulatory checkpoints, cancer vaccines, adoptive cell transfer, combination therapies, as well as different routes of administration. Most of approaches showed signs of anti-cancer activity and a good safety profile in early-phase clinical trials. Since IO provided benefit only to a small subgroup of TNBC patients so far, identifying predictive biomarkers is a priority to refine patient-selection. Data from ongoing clinical trials, with the gradually improving interpretation of the breast tumor immune environment, will hopefully refine the role of new immune targets for the treatment of TNBC.

Immune checkpoint inhibition for pancreatic ductal adenocarcinoma: limitations and prospects: a systematic review

Pancreatic cancer is an extremely malignant tumor with the lowest 5-year survival rate among all tumors. Pancreatic ductal adenocarcinoma (PDAC), as the most common pathological subtype of pancreatic cancer, usually has poor therapeutic results. Immune checkpoint inhibitors (ICIs) can relieve failure of the tumor-killing effect of immune effector cells caused by immune checkpoints. Therefore, they have been used as a novel treatment for many solid tumors. However, PDAC is not sensitive to monotherapy with ICIs, which might be related to the inhibitory immune microenvironment of pancreatic cancer. Therefore, the way to improve the microenvironment has raised a heated discussion in recent years. Here, we elaborate on the relationship between different immune cellular components in this environment, list some current preclinical or clinical attempts to enhance the efficacy of ICIs by targeting the inhibitory tumor microenvironment of PDAC or in combination with other therapies. Such information offers a better understanding of the sophisticated tumor-microenvironment interactions, also providing insights on therapeutic guidance of PDAC targeting. Video Abstract.

Prognosis and Immunotherapy Significances of a Cancer-Associated Fibroblasts-Related Gene Signature in Gliomas

As a cold tumor, malignant glioma has strong immunosuppression and immune escape characteristics. The tumor microenvironment (TME) provides the "soil" for the survival of malignant tumors, and cancer-associated fibroblasts (CAFs) are the architects of matrix remodeling in TME. Therefore, CAFs have potent regulatory effects on the recruitment and functional differentiation of immune cells, whereby they synthesize and secrete numerous collagens, cytokines, chemokines, and other soluble factors whose interaction with tumor cells creates an immunosuppressive TME. This consequently facilitates the immune escape of tumor cells. Targeting CAFs would improve the TME and enhance the efficacy of immunotherapy. Thus, regulation of CAFs and CAFs-related genes holds promise as effective immunotherapies for gliomas. Here, by analyzing the Chinese Glioma Genome Atlas and the Cancer Genome Atlas database, the proportion of CAFs in the tumor was revealed to be associated with clinical and immune characteristics of gliomas. Moreover, a risk model based on the expression of CAFs-related six-gene for the assessment of glioma patients was constructed using the least absolute shrinkage and selection operator and the results showed that a high-risk group had a higher expression of the CAFs-related six-genes and lower overall survival rates compared with those in the low-risk group. Additionally, patients in the high-risk group exhibited older age, high tumor grade, isocitrate dehydrogenase wildtype, 1p/19q non-codeletion, O-6-methylguanine-DNA methyltransferase promoter unmethylation and poor prognosis. The high-risk subtype had a high proportion CAFs in the TME of glioma, and a high expression of immune checkpoint genes. Analysis of the Submap algorithm indicated that the high-risk patients could show potent response to anti-PD-1 therapy. The established risk prediction model based on the expression of six CAFs-related genes has application prospects as an independent prognostic indicator and a predictor of the response of patients to immunotherapy.

How Tim proteins differentially exploit membrane features to attain robust target sensitivity

Immune surveillance cells such as T cells and phagocytes utilize integral plasma membrane receptors to recognize surface signatures on triggered and activated cells such as those in apoptosis. One such family of plasma membrane sensors, the transmembrane immunoglobulin and mucin domain (Tim) proteins, specifically recognize phosphatidylserine (PS) but elicit distinct immunological responses. The molecular basis for the recognition of lipid signals on target cell surfaces is not well understood. Previous results suggest that basic side chains present at the membrane interface on the Tim proteins might facilitate association with additional anionic lipids including but not necessarily limited to PS. We, therefore, performed a comparative quantitative analysis of the binding of the murine Tim1, Tim3, and Tim4, to synthetic anionic phospholipid membranes under physiologically relevant conditions. X-ray reflectivity and vesicle binding studies were used to compare the water-soluble domain of Tim3 with results previously obtained for Tim1 and Tim4. Although a calcium link was essential for all three proteins, the three homologs differed in how they balance the hydrophobic and electrostatic interactions driving membrane association. The proteins also varied in their sensing of phospholipid chain unsaturation and showed different degrees of cooperativity in their dependence on bilayer PS concentration. Surprisingly, trace amounts of anionic phosphatidic acid greatly strengthened the bilayer association of Tim3 and Tim4, but not Tim1. A novel mathematical model provided values for the binding parameters and illuminated the complex interplay among ligands. In conclusion, our results provide a quantitative description of the contrasting selectivity used by three Tim proteins in the recognition of phospholipids presented on target cell surfaces. This paradigm is generally applicable to the analysis of the binding of peripheral proteins to target membranes through the heterotropic cooperative interactions of multiple ligands.

Pre-clinical development and molecular characterization of an engineered type 1 regulatory T-cell product suitable for immunotherapy

BACKGROUND AIMS

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative therapeutic approach for many hematological disorders. However, allo-HSCT is frequently accompanied by a serious side effect: graft-versus-host disease (GVHD). The clinical use of allo-HSCT is limited by the inability of current immunosuppressive regimens to adequately control GvHD without impairing the graft-versus-leukemia effect (GvL) conferred by transplanted healthy immune cells. To address this, the authors have developed an engineered type 1 regulatory T-cell product called CD4IL-10 cells. CD4IL-10 cells are obtained through lentiviral transduction, which delivers the human IL10 gene into purified polyclonal CD4+ T cells. CD4IL-10 cells may provide an advantage over standard-of-care immunosuppressants because of the ability to suppress GvHD through continuous secretion of IL-10 and enhance the GvL effect in myeloid malignancies through targeted killing of malignant myeloid cells.

METHODS

Here the authors established a production process aimed at current Good Manufacturing Practice (cGMP) production for CD4IL-10 cells.

RESULTS

The authors demonstrated that the CD4IL-10 cell product maintains the suppressive and cytotoxic functions of previously described CD4IL-10 cells. In addition, RNA sequencing analysis of CD4IL-10 identified novel transcriptome changes, indicating that CD4IL-10 cells primarily upregulate cytotoxicity-related genes. These include four molecules with described roles in CD8+ T and natural killer cell-mediated cytotoxicity: CD244, KLRD1, KLRC1 and FASLG. Finally, it was shown that CD4IL-10 cells upregulate IL-22, which mediates wound healing and tissue repair, particularly in the gut.

CONCLUSIONS

Collectively, these results pave the way toward clinical translation of the cGMP-optimized CD4IL-10 cell product and uncover new molecules that have a role in the clinical application of CD4IL-10 cells.

TIM-3 in Leukemia; Immune Response and Beyond

T cell immunoglobulin and mucin domain 3 (TIM-3) expression on malignant cells has been reported in some leukemias. In myelodysplastic syndrome (MDS), increased TIM-3 expression on TH1 cells, regulatory T cells, CD8+ T cells, and hematopoietic stem cells (HSCs), which play a role in the proliferation of blasts and induction of immune escape, has been reported. In AML, several studies have reported overexpression of TIM-3 on leukemia stem cells (LSCs) but not on healthy HSCs. Overexpression of TIM-3 on exhausted CD4+ and CD8+ T cells and leukemic cells in CML, ALL, and CLL patients could be a prognostic risk factor for poor therapeutic response and relapse in patients. Currently, several TIM-3 inhibitors are used in clinical trials for leukemias, and some have shown encouraging response rates for MDS and AML treatment. For AML immunotherapy, blockade TIM-3 may have dual effects: directly inhibiting AML cell proliferation and restoring T cell function. However, blockade of PD-1 and TIM-3 fails to restore the function of exhausted CD8+ T cells in the early clinical stages of CLL, indicating that the effects of TIM-3 blockade may be different in AML and other leukemias. Thus, further studies are required to evaluate the efficacy of TIM-3 inhibitors in different types and stages of leukemia. In this review, we summarize the biological functions of TIM-3 and its contribution as it relates to leukemias. We also discuss the effects of TIM-3 blockade in hematological malignancies and clinical trials of TIM-3 for leukemia therapy.

Nature vs. Nurture: The Two Opposing Behaviors of Cytotoxic T Lymphocytes in the Tumor Microenvironment

Similar to Janus, the two-faced god of Roman mythology, the tumor microenvironment operates two opposing and often conflicting activities, on the one hand fighting against tumor cells, while on the other hand, favoring their proliferation, survival and migration to other sites to establish metastases. In the tumor microenvironment, cytotoxic T cells-the specialized tumor-cell killers-also show this dual nature, operating their tumor-cell directed killing activities until they become exhausted and dysfunctional, a process promoted by cancer cells themselves. Here, we discuss the opposing activities of immune cells populating the tumor microenvironment in both cancer progression and anti-cancer responses, with a focus on cytotoxic T cells and on the molecular mechanisms responsible for the efficient suppression of their killing activities as a paradigm of the power of cancer cells to shape the microenvironment for their own survival and expansion.