High-Density Infiltration of V-domain Immunoglobulin Suppressor of T-cell Activation Up-regulated Immune Cells in Human Pancreatic Cancer

Tumor immune microenvironment alterations associated with progression in human intraductal papillary mucinous neoplasms

Pancreatic ductal adenocarcinoma (PDAC) poses a significant challenge due to late-stage diagnoses. To improve patient outcomes, early intervention in precursor lesions such as intraductal papillary mucinous neoplasm (IPMN) is crucial. However, early intervention must be balanced against overtreatment of low-risk lesions that are unlikely to progress, underscoring the need to better understand molecular alterations in neoplastic cells and changes in the tumor microenvironment (TME) that drive the progression of IPMNs. In this study, we characterized alterations in the TME of IPMNs as they progressed to high-grade dysplasia, using immunohistochemistry to quantify immune cell density and activation status in more than 100 well-characterized human IPMN samples. Analyses revealed progression to a more immunosuppressive TME in high-grade IPMN compared with low-grade IPMN, characterized by elevated expression of immune checkpoint molecules (PD-L1, TIM3, VISTA), increased density of macrophages, and decreased density of cytotoxic T cells. Intriguingly, the alterations in macrophages were limited to focal regions of high-grade dysplasia, while T-cell alterations affected the entire IPMN. Additionally, elevated VISTA expression was associated with poorer clinical outcome after IPMN resection in an independent cohort. These findings provide important insights into the interplay between the immune microenvironment and IPMN progression, highlighting potential targets to modify the TME for cancer interception. © 2025 The Pathological Society of Great Britain and Ireland.

Intracellular and exosomal localization of the negative checkpoint regulator VISTA in immune cells

Strategies in immunotherapy often target the immunosuppressive environment of tumor cells. One route of therapeutic interference could involve negative checkpoint regulators of which V-domain immunoglobulin (Ig)-containing suppressor of T-cell activation (VISTA) has raised more interest recently. The protein is expressed on the surface of tumor cells, T-lymphocytes, and antigen-presenting cells (APCs), but its intracellular expression pattern has not been investigated yet. We examined the intracellular distribution of VISTA and its possible role in translocation processes by immunofluorescence and Western blots. We analyzed the expression and localization of VISTA in murine bone marrow-derived macrophages (BMDMs), human monocyte-derived macrophages, and human T lymphocytes (Jurkat). We obtained different cell fractions and organelles of various cell types and analyzed for the presence of VISTA. Monitoring a VISTA-GFP fusion construct in transfected cell lines HL-60 and THP-1 confirmed VISTA localization in these cell lines. All used cell lines showed the colocalization of VISTA and several vesicle markers together with VISTA staining along microtubule fibers. Additionally, we found VISTA in secreted exosomes and have the first hints for nucleic expression in all tested cell lines. Therefore, the storage of VISTA in vesicles and its potential presence in nuclei resembles two other well-described checkpoint regulators, CTLA-4 and PD-L1, respectively. We conclude that VISTA storage in vesicles enables a fast response to immunogenic stimuli, which needs to be considered for inhibitory experiments. The localization of VISTA in exosomes suggests a signaling function to facilitate cell-cell communication. Furthermore, the VISTA expression in the nucleus proposes a transcriptional role.

Pan-cancer analysis of co-inhibitory molecules revealing their potential prognostic and clinical values in immunotherapy

Background

The widespread use of immune checkpoint inhibitors (anti-CTLA4 or PD-1) has opened a new chapter in tumor immunotherapy by providing long-term remission for patients. Unfortunately, however, these agents are not universally available and only a minority of patients respond to them. Therefore, there is an urgent need to develop novel therapeutic strategies targeting other co-inhibitory molecules. However, comprehensive information on the expression and prognostic value of co-inhibitory molecules, including co-inhibitory receptors and their ligands, in different cancers is not yet available.

Methods

We investigated the expression, correlation, and prognostic value of co-inhibitory molecules in different cancer types based on TCGA, UCSC Xena, TIMER, CellMiner datasets. We also examined the associations between the expression of these molecules and the extent of immune cell infiltration. Besides, we conducted a more in-depth study of VISTA.

Result

The results of differential expression analysis, correlation analysis, and drug sensitivity analysis suggest that CTLA4, PD-1, TIGIT, LAG3, TIM3, NRP1, VISTA, CD80, CD86, PD-L1, PD-L2, PVR, PVRL2, FGL1, LGALS9, HMGB1, SEMA4A, and VEGFA are associated with tumor prognosis and immune cell infiltration. Therefore, we believe that they are hopefully to serve as prognostic biomarkers for certain cancers. In addition, our analysis indicates that VISTA plays a complex role and its expression is related to TMB, MSI, cancer cell stemness, DNA/RNA methylation, and drug sensitivity.

Conclusions

These co-inhibitory molecules have the potential to serve as prognostic biomarkers and therapeutic targets for a broad spectrum of cancers, given their strong associations with key clinical metrics. Furthermore, the analysis results indicate that VISTA may represent a promising target for cancer therapy.

A pair of promising immune checkpoints PSGL-1 and VISTA from immunotolerance to immunotherapy

Immune checkpoints are crucial for regulating immune responses and maintaining self-tolerance, as they play a pivotal role in preventing autoimmunity and facilitating tumor immune evasion. This review concentrates on the immune checkpoint molecules PSGL-1 and VISTA. Both molecules are highly expressed in hematopoietic cells, including T cells and myeloid cells. VISTA functions both as a ligand on myeloid cells, where it regulates cytokine production, chemotaxis, and phagocytosis while promoting their differentiation into a tolerogenic phenotype and as a receptor on T cells, where it contributes to T cell quiescence. PSGL-1, which acts as a binding partner for VISTA, further inhibits T-cell activation and fosters tolerance within the acidic tumor microenvironment. Our review provides a comprehensive analysis of the structure, expression, and biological functions of PSGL-1 and VISTA and emphasizes their therapeutic potential in cancer treatment, autoimmune diseases, and transplantation. The dual role of these checkpoints in immune regulation presents novel opportunities for advancing cancer immunotherapy and developing new strategies for managing autoimmune conditions.

VISTA-mediated immune evasion in cancer

Over the past decade, V-domain immunoglobulin suppressor of T-cell activation (VISTA) has been established as a negative immune checkpoint molecule. Since the role of VISTA in inhibiting T-cell activation was described, studies have demonstrated other diverse regulatory functions in multiple immune cell populations. Furthermore, its relevance has been identified in human cancers. The role of VISTA in cancer immune evasion has been determined, but its mechanisms in the tumor microenvironment remain to be further elucidated. Understanding its contributions to cancer initiation, progression, and resistance to current treatments will be critical to its utility as a target for novel immunotherapies. Here, we summarize the current understanding of VISTA biology in cancer.

VISTA: A Novel Checkpoint for Cancer Immunotherapy

V-domain Ig suppressor of T cell activation (VISTA) is a recently identified member of the B7 family of immunoregulatory proteins. It is pivotal for maintaining T cell quiescence and exerts a significant regulatory influence on the immune response to tumors. Accumulating clinical evidence suggests that the influence of VISTA on tumor immunity is more nuanced than initially postulated. Although these revelations add layers of complexity to our understanding of the function of VISTA, they also offer novel avenues for scientific inquiry and potential therapeutic targets. In this review, we scrutinize the current literature pertaining to the expression of VISTA in various of malignancies, aiming to elucidate its intricate roles within the tumor microenvironment and in cancer immunotherapy.

Expression and function of VISTA on myeloid cells

V-domain containing Ig Suppressor of T cell Activation (VISTA) is predominantly expressed on myeloid cells and functions as a ligand/receptor/soluble molecule. In inflammatory responses and immune responses, VISTA regulates multiple functions of myeloid cells, such as chemotaxis, phagocytosis, T cell activation. Since inflammation and immune responses are critical in many diseases, VISTA is a promising therapeutic target. In this review, we will describe the expression and function of VISTA on different myeloid cells, including neutrophils, monocytes, macrophages, dendritic cells (DCs), myeloid-derived suppressor cells (MDSCs). In addition, we will discuss whether the functions of VISTA on these cells impact the disease processing.

Novel targets for immune-checkpoint inhibition in cancer

Immune-checkpoint inhibitors have revolutionized cancer therapy, yet many patients either do not derive any benefit from treatment or develop a resistance to checkpoint inhibitors. Intrinsic resistance can result from neoantigen depletion, defective antigen presentation, PD-L1 downregulation, immune-checkpoint ligand upregulation, immunosuppression, and tumor cell phenotypic changes. On the other hand, extrinsic resistance involves acquired upregulation of inhibitory immune-checkpoints, leading to T-cell exhaustion. Current data suggest that PD-1, CTLA-4, and LAG-3 upregulation limits the efficacy of single-agent immune-checkpoint inhibitors. Ongoing clinical trials are investigating novel immune-checkpoint targets to avoid or overcome resistance. This review provides an in-depth analysis of the evolving landscape of potentially targetable immune-checkpoints in cancer. We highlight their biology, emphasizing the current understanding of resistance mechanisms and focusing on promising strategies that are under investigation. We also summarize current results and ongoing clinical trials in this crucial field that could once again revolutionize outcomes for cancer patients.

Clinical and research updates on the VISTA immune checkpoint: immuno-oncology themes and highlights

Immune checkpoints limit the activation of the immune system and serve an important homeostatic function but can also restrict immune responses against tumors. Inhibition of specific immune checkpoint proteins such as the B7:CD28 family members programmed cell death protein-1 (PD-1) and cytotoxic T-lymphocyte antigen-4 (CTLA-4) has transformed the treatment of various cancers by promoting the anti-tumor activation of immune cells. In contrast to these effects, the V-domain immunoglobulin suppressor of T-cell activation (VISTA) regulates the steady state of the resting immune system and promotes homeostasis by mechanisms distinct from PD-1 and CTLA-4. The effects of VISTA blockade have been shown to include a decrease in myeloid suppression coupled with proinflammatory changes by mechanisms that are separate and distinct from other immune checkpoint proteins; in some preclinical studies these immune effects appear synergistic. Given the potential benefits of VISTA blockade in the context of cancer therapy, the second Annual VISTA Symposium was convened virtually on September 23, 2022, to review new research from investigators and immuno-oncology experts. Discussions in the meeting extended the knowledge of VISTA biology and the effects of VISTA inhibition, particularly on cells of the myeloid lineage and resting T cells, as three candidate anti-VISTA antibodies are in, or nearing, clinical development.

Expression of PD-L1 and VISTA in Intraductal Papillary Mucinous Neoplasm With Associated Invasive Carcinoma of the Pancreas

Early detection and treatment of invasive carcinoma arising in association with intraductal papillary mucinous neoplasm (IPMN), which is biologically and (epi)genetically distinct from conventional pancreatic ductal adenocarcinoma, provide an opportunity to improve the prognosis of this lethal disease. Despite the successful application of programmed death (ligand) 1 (PD-[L]1)-blocking strategies in numerous cancers, the immune microenvironment of IPMN with associated invasive carcinoma remains elusive. Here, we investigated CD8+ T cells, CD68+ macrophages, PD-L1, and V-domain immunoglobulin suppressor of T-cell activation (VISTA) in 60 patients with IPMN with associated invasive carcinoma using immunohistochemistry, explored their correlations with clinicopathologic variables and prognosis, and compared them with those in 76 patients with IPMN without invasive carcinoma (60 low-grade and 16 high-grade lesions). Using antibodies against CD8, CD68, and VISTA, we evaluated tumor-infiltrating immune cells in 5 high-power fields (×400) and calculated the corresponding mean counts. PD-L1 with a combined positive score of ≥1 was regarded as positive, and VISTA expression on tumor cells (TCs) was deemed positive when ≥1% of TCs showed membranous/cytoplasmic staining. A reduction of CD8+ T cells and an increase of macrophages were observed during carcinogenesis. Positive PD-L1 combined positive score and VISTA expression on TCs were 13% and 11% in the intraductal component of IPMN with associated invasive carcinoma, 15% and 12% in the associated invasive carcinoma, and 6% and 4% in IPMN without an invasive carcinoma, respectively. Interestingly, the PD-L1 positivity rate was the highest in a subset of associated invasive carcinomas (predominantly gastric-type-derived) and was associated with higher counts of CD8+ T cells, macrophages, and VISTA+ immune cells. Accumulation of VISTA+ immune cells was observed in the intraductal component of IPMN with associated invasive carcinoma compared with that of low-grade IPMN, whereas in intestinal-type IPMN with associated invasive carcinoma, the number of these cells decreased during the transition from the intraductal component to the associated invasive carcinoma. Survival analysis revealed that a higher number of macrophages predicted poorer prognosis. In conclusion, our results might help in individualized immunotherapeutic strategies for these patients.

VISTA expression and patient selection for immune-based anticancer therapy

V-domain Ig suppressor of T-cell activation (VISTA) is a B7 family member that plays key roles in maintaining T cell quiescence and regulation of myeloid cell populations, which together establish it as a novel immunotherapy target for solid tumors. Here we review the growing literature on VISTA expression in relation to various malignancies to better understand the role of VISTA and its interactions with both tumor cells and immune cells expressing other checkpoint molecules within the tumor microenvironment (TME). The biology of VISTA creates several mechanisms to maintain the TME, including supporting the function of myeloid-derived suppressor cells, regulating natural killer cell activation, supporting the survival of regulatory T cells, limiting antigen presentation on antigen-presenting cells and maintaining T cells in a quiescent state. Understanding these mechanisms is an important foundation of rational patient selection for anti-VISTA therapy. We provide a general framework to describe distinct patterns of VISTA expression in correlation with other known predictive immunotherapy biomarkers (programmed cell death ligand 1 and tumor-infiltrating lymphocytes) across solid tumors to facilitate investigation of the most efficacious TMEs for VISTA-targeted treatment as a single agent and/or in combination with anti-programmed death 1/anti-cytotoxic T lymphocyte antigen-4 therapies.

High VISTA expression is linked to a potent epithelial-mesenchymal transition and is positively correlated with PD1 in breast cancer

Breast cancer is the most common type of tumor in women worldwide. Immune checkpoint inhibitors, particularly anti-PDL1, have shown promise as a therapeutic approach for managing this disease. However, this type of immunotherapy still fails to work for some patients, leading researchers to explore alternative immune checkpoint targets. The Ig suppressor of T cell activation domain V (VISTA) has emerged as a novel immune checkpoint that delivers inhibitory signals to T cells and has demonstrated encouraging results in various cancers. Our study investigated the association of VISTA expression with clinicopathological parameters in breast cancer patients, its involvement in the Epithelial-Mesenchymal-Transition (EMT) process, and its correlation with PD1 expression. Transcriptomic analysis revealed that VISTA was associated with lobular and metaplastic histological type, tumor size, lymph node status, ER and PR negative status, and the TNBC molecular subtype. Furthermore, VISTA expression was strongly associated with an immunosuppressive tumor microenvironment. Immunohistochemistry analysis corroborated the transcriptomic results, indicating that VISTA was expressed in most immune cells (94%) and was significantly expressed in breast cancer tumor cells compared to matched adjacent tissues. Our study also showed for the first time that VISTA overexpression in breast cancer cells could be associated with the EMT process. Additionally, we identified a positive correlation between VISTA and PD-1 expression. Together, these results highlight the immunosuppressive effect of VISTA in breast cancer patients and suggest that bi-specific targeting of VISTA and PD-1 in combination therapy could be beneficial for these patients.

B7 Family Members in Pancreatic Ductal Adenocarcinoma: Attractive Targets for Cancer Immunotherapy

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers, with a five-year survival rate of approximately 5-10%. The immune checkpoint blockade represented by PD-1/PD-L1 inhibitors has been effective in a variety of solid tumors but has had little clinical response in pancreatic cancer patients. The unique suppressive immune microenvironment is the primary reason for this outcome, and it is essential to identify key targets to remodel the immune microenvironment. Some B7 family immune checkpoints, particularly PD-L1, PD-L2, B7-H3, B7-H4, VISTA and HHLA2, have been identified as playing a significant role in the control of tumor immune responses. This paper provides a comprehensive overview of the recent research progress of some members of the B7 family in pancreatic cancer, which revealed that they can be involved in tumor progression through immune-dependent and non-immune-dependent pathways, highlighting the mechanisms of their involvement in tumor immune escape and assessing the prospects of their clinical application. Targeting B7 family immune checkpoints is expected to result in novel immunotherapeutic treatments for patients with pancreatic cancer.

Tumor Budding Is an Independent Prognostic Factor in Pancreatic Adenocarcinoma and It Positively Correlates with PD-L1 Expression on Tumor Cells

Pancreatic adenocarcinoma is one of the leading causes of cancer-related death in developed countries. Only 15% of patients are candidates for radical surgery, and adequate prognostication may guide proper postsurgical management. We aimed to retrospectively assess the prognostic significance of the immunohistochemical expression of immune checkpoint receptors (PD-L1 and VISTA), markers of systemic inflammation, thrombosis in the tumor area, and the tumor budding in the group of 107 patients diagnosed with pancreatic adenocarcinoma in a single center. The high expression of PD-L1 on tumor cells (TCs) was associated with worse overall survival (OS, p = 0.041, log-rank). On the contrary, high PD-L1 or VISTA on tumor-associated immune cells (TAICs) was correlated with better OS (p = 0.006 and p = 0.008, respectively, log-rank). The joint status of PD-L1 on TCs and TAICs stratified patients into three prognostic groups. The cases with high-grade budding were characterized by higher PD-L1 expression on TCs (p = 0.008) and elevated systemic inflammatory markers. Moreover, budding was identified as the independent prognostic factor in multivariate Cox regression analysis (HR = 2.87; 95% CI = 1.75−4.68; p < 0.001). To conclude, the pattern of PD-L1 and VISTA expression was associated with survival in univariate analysis. Tumor budding accurately predicts outcomes in pancreatic cancer and should be incorporated into routine histopathological practice.

Discovery of Novel Inhibitors From Medicinal Plants for V-Domain Ig Suppressor of T-Cell Activation

V-domain Ig suppressor of T cell activation (VISTA) is an immune checkpoint and is a type I transmembrane protein. VISTA is linked to immunotherapy resistance, and it is a potential immune therapeutic target, especially for triple-negative breast cancer. It expresses at a high concentration in regulatory T cells and myeloid-derived suppressor cells, and its functional blockade is found to delay tumor growth. A useful medicinal plant database for drug designing (MPD3), which is a collection of phytochemicals from diverse plant families, was employed in virtual screening against VISTA to prioritize natural inhibitors against VISTA. Three compounds, Paratocarpin K (PubChem ID: 14187087), 3-(1H-Indol-3-yl)-2-(trimethylazaniumyl)propanoate (PubChem ID: 3861164), and 2-[(5-Benzyl-4-ethyl-1,2,4-triazol-3-yl)sulfanylmethyl]-5-methyl-1,3,4-oxadiazole (PubChem ID: 6494266), having binding energies stronger than -6 kcal/mol were found to have two common hydrogen bond interactions with VISTA active site residues: Arg54 and Arg127. The dynamics of the compound-VISTA complexes were further explored to infer binding stability of the systems. Results revealed that the compound 14187087 and 6494266 systems are highly stable with an average RMSD of 1.31 Å. Further affirmation on the results was achieved by running MM-GBSA on the MD simulation trajectories, which re-ranked 14187087 as the top-binder with a net binding energy value of -33.33 kcal/mol. In conclusion, the present study successfully predicted natural compounds that have the potential to block the function of VISTA and therefore can be utilized further in experimental studies to validate their real anti-VISTA activity.

Emodin Alleviates Intestinal Barrier Dysfunction by Inhibiting Apoptosis and Regulating the Immune Response in Severe Acute Pancreatitis

OBJECTIVE

The intestinal barrier injury caused by severe acute pancreatitis (SAP) can induce enterogenous infection, further aggravating the inflammatory reactions and immune responses. This study aimed to test the hypothesis that emodin protects the intestinal function and is involved in the immune response in SAP.

METHODS

The network pharmacology was established using the Swiss target prediction and pathway enrichment analysis. The SAP mice model was induced by cerulein (50 μg/kg) and lipopolysaccharide (10 mg/kg) hyperstimulation. The pharmacological effect of emodin in treating SAP was evaluated at mRNA and protein levels by various methods.

RESULTS

The network analysis provided the connectivity between the targets of emodin and the intestinal barrier-associated proteins and predicted the BAX/Bcl-2/caspase 3 signaling pathway. Emodin alleviated the pathological damages to the pancreas and intestine and reduced the high concentrations of serum amylase and cytokines in vivo. Emodin increased the expression of intestinal barrier-related proteins and reversed the changes in the apoptosis-related proteins in the intestine. Simultaneously, emodin regulated the ratio of T helper type 1 (TH1), TH2, TH17, γδ T cells, and interferon γ/interleukin 17 producing γδ T cells.

CONCLUSIONS

These findings partly verified the mechanism underlying the regulation of the intestinal barrier and immune response by emodin.

Immune functions as a ligand or a receptor, cancer prognosis potential, clinical implication of VISTA in cancer immunotherapy

Since cancer immunotherapy with immune checkpoint inhibitors of PD/PDL-1 and CTLA-4 limited efficacy to the patients due to resistance during the current decade, novel target is required for customized treatment due to tumor heterogeneity. V-domain Ig-containing suppressor of T cell activation (VISTA), a programmed death protein-1(PD-1) homolog expressed on T cells and on antigen presenting cells(APC), has emerged as a new target in several cancers. Though VISTA inhibitors including CA-170 are considered attractive in cancer immunotherapy to date, the information on VISTA as a potent biomarker of cancer prognosis and its combination therapy is still lacking to date. Thus, in this review, we discussed extracellular domain, ligands, expression, immune functions and clinical implications of VISTA and finally suggested conclusion and perspectives.

Identification of active small-molecule modulators targeting the novel immune checkpoint VISTA

Background

Cancer immunotherapy has gained increasing popularity as a novel approach to treat cancer. A member of the B7 family, V-domain immunoglobulin suppressor of T-cell activation (VISTA) is a novel immune checkpoint that regulates a broad spectrum of immune responses. VISTA is an acidic pH-selective ligand for P-selectin glycoprotein ligand-1(PSGL-1). CA-170, a first-in-class small-molecule dual antagonist of VISTA/PD-L1, was collaboratively developed by Aurigene Discovery Technologies Limited and Curis, Inc. It is currently in Phase I clinical trial.

Results

In this study, we develop homology modeling for the VISTA 3D structure and subsequent virtual screening for VISTA small-molecule hit ligands. Visualization of the binding postures of docked ligands with the VISTA protein indicates that some small molecular compounds target VISTA. The ability of antagonist to disrupt immune checkpoint VISTA pathways was investigated though functional studies in vitro.

Conclusions

Affinity active molecule for VISTA was obtained through virtual screening, and the antagonist compound activity to VISTA was assayed in cellular level. We reported a small molecule with high VISTA affinity as antagonist, providing ideas for development VISTA-targeted small molecule compound in cancer immunotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-021-00446-4.

Detection of Immune Checkpoint Receptors - A Current Challenge in Clinical Flow Cytometry

Immunological therapy principles are increasingly determining modern medicine. They are used to treat diseases of the immune system, for tumors, but also for infections, neurological diseases, and many others. Most of these therapies base on antibodies, but small molecules, soluble receptors or cells and modified cells are also used. The development of immune checkpoint inhibitors is amazingly fast. T-cell directed antibody therapies against PD-1 or CTLA-4 are already firmly established in the clinic. Further targets are constantly being added and it is becoming increasingly clear that their expression is not only relevant on T cells. Furthermore, we do not yet have any experience with the long-term systemic effects of the treatment. Flow cytometry can be used for diagnosis, monitoring, and detection of side effects. In this review, we focus on checkpoint molecules as target molecules and functional markers of cells of the innate and acquired immune system. However, for most of the interesting and potentially relevant parameters, there are still no test kits suitable for routine use. Here we give an overview of the detection of checkpoint molecules on immune cells in the peripheral blood and show examples of a possible design of antibody panels.

VISTA: A Promising Target for Cancer Immunotherapy?

Agents targeting the B7 family co-inhibitory receptors cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed cell death protein-1 (PD-1), or its ligand (PD-L1), have a pivotal role in clinical practice. V-domain Ig suppressor of T-cell activation (VISTA) is a protein highly conserved between species, with a similar amino acid sequence to the B7 family members, characterized by a particularly structural homology to PD-1. It has been counted as an emerging target within the list of novel targetable immune checkpoints in oncology. Physiologically, VISTA exerts a regulatory function on the immune system at several levels, particularly by modulating T cells activation. Its altered activity plays a role in many autoimmune diseases, and its expression has been found to be prognostically implicated in different cancer types in preclinical models. We hereby present the main evidence on the value of VISTA as an immune checkpoint in solid and hematological malignancies. We also review its value as a potential target for cancer immunotherapy, by reporting the results of Phase I and II clinical trials assessing the use of drugs targeting VISTA. The complexity of its pathway, along with some unclear biological aspects concerning its molecular interactions, currently represent a limit to the applicability of VISTA as an effective biomarker for immunotherapy in oncology. A deeper characterization of this immune checkpoint may help defining its value within immune signatures of solid and hematological malignancies, and to design future therapeutic strategies.

The Role of V-Domain Ig Suppressor of T Cell Activation (VISTA) in Cancer Therapy: Lessons Learned and the Road Ahead

Immune checkpoints (ICs) have pivotal roles in regulating immune responses. The inhibitory ICs in the tumor microenvironment (TME) have been implicated in the immune evasion of tumoral cells. Therefore, identifying and targeting these inhibitory ICs might be critical for eliminating tumoral cells. V-domain immunoglobulin suppressor of T cell activation (VISTA) is a novel inhibitory IC that is expressed on myeloid cells, lymphoid cells, and tumoral cells; therefore, VISTA can substantially regulate innate and adaptive anti-tumoral immune responses. Besides, growing evidence indicates that VISTA blockade can enhance the sensitivity of tumoral cells to conventional IC-based immunotherapy, e.g., cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors. In this regard, the current study aimed to review the current evidence about the structure and expression pattern of VISTA, its role in TME, the clinicopathological significance of VISTA, and its prognostic values in various cancers. Besides, this review intended to collect the lessons from the recent pre-clinical and clinical studies and propose a strategy to overcome tumor immune-resistance states.

Pancreatic Cancer Signaling Pathways, Genetic Alterations, and Tumor Microenvironment: The Barriers Affecting the Method of Treatment

Genetic alterations, especially the K-Ras mutation, carry the heaviest burden in the progression of pancreatic precursor lesions into pancreatic ductal adenocarcinoma (PDAC). The tumor microenvironment is one of the challenges that hinder the therapeutic approaches from functioning sufficiently and leads to the immune evasion of pancreatic malignant cells. Mastering the mechanisms of these two hallmarks of PDAC can help us in dealing with the obstacles in the way of treatment. In this review, we have analyzed the signaling pathways involved in PDAC development and the immune system's role in pancreatic cancer and immune checkpoint inhibition as next-generation therapeutic strategy. The direct targeting of the involved signaling molecules and the immune checkpoint molecules, along with a combination with conventional therapies, have reached the most promising results in pancreatic cancer treatment.

V-domain Ig suppressor of T cell activation (VISTA) inhibition is a new approach to cancer therapy: a Bibliometric study

V-domain Ig suppressor of T cell activation (VISTA) is a transmembrane protein that plays a crucial role in the regulation of antitumor immunity. Therapeutic intervention that inhibits the VISTA pathway constitutes a new approach in the treatment of cancer. The aim of the present study was to provide a bibliometric literature review of VISTA research in the field of cancer. Published articles on the topic were retrieved from the Web of Science Core Collection Database of Hassan II University from the beginning of the database to November 14, 2019. The articles were analyzed and a lot of information was available on the Web of Science, such as the number of citations, the names of the authors, country, publication year, Web of Science categories, and journal. A total of 76 papers (research and review articles) were retrieved from the Web of Science Core Collection Database to introduce VISTA research in cancer topic. All of the articles were published in English during the period between 2011 and 2019; the annual publications number has increased from 1 in 2011 to 22 in 2019. Cancer immunology immunotherapy journal, Cancer immunology research journal, and Cancer research journal, each one has published 3 articles (3.9% of the total publications), the impact factors of the journals ranged from 2.34 to 10.19. The author who has published high number of articles was Noelle RJ with 11 articles; according to the keyword co-occurrence, VISTA was the most frequent keyword with a frequency of 42.1%, followed by immune (36.8%). This is the first work that treats the application of bibliometric methods in VISTA research in the oncology field and represents an important bibliographic source for future studies on the role of VISTA in cancer and immunotherapy of cancer.

Prognostic significance and therapeutic potential of the immune checkpoint VISTA in pancreatic cancer

OBJECTIVE

V-domain Ig suppressor of T cell activation (VISTA) is a novel immune checkpoint protein that belongs to the B7 family. The aim of this study was to investigate the prognostic significance and therapeutic potential of VISTA in patients with pancreatic cancer.

METHODS

Using immunohistochemistry (IHC), we examined the expression of VISTA and demonstrated the associations between the VISTA and overall survival in 223 PDAC patients from 2 different unrelated retrospective cohorts. The multiplex immunofluorescence was performed to illuminate the relationship between VISTA expression and tumor-infiltrating immune cell subclusters of PDAC. We also verified the findings in The Cancer Genome Atlas (TCGA) dataset. The anti-tumor effect of anti-VISTA therapy was studied by the mouse model with liver metastases of PDAC.

RESULTS

The VISTA protein was highly expressed in 25.6% of tumor cells (TCs), 38.1% of immune cells, and 26.0% of endothelial cells in 223 PDAC tumor tissues. VISTA expression in TCs was significantly associated with prolonged overall survival. Multiplex immunofluorescence analysis revealed that VISTA level was positively correlated with CD68+ macrophages, CD3+ T cells, and CD19+ B cells in PDAC. However, a higher expression level of VISTA was detected in tumor-infiltrating CD68+ macrophages than in CD3+ T and CD19+ B cells. Furthermore, anti-VISTA antibody treatment significantly reduced the number of metastatic nodules in livers of mouse models of PDAC with liver metastases.

CONCLUSION

VISTA expressed in TCs is associated with a favorable prognosis in PDAC. Moreover, immunotherapy with anti-VISTA antibodies may potentially be an effective treatment strategy against PDAC.

The Expression Pattern and Clinical Significance of the Immune Checkpoint Regulator VISTA in Human Breast Cancer

Background

Immunotherapies targeting CTLA-4 and PD-1 have elicited promising responses in a variety of cancers. However, the relatively low response rates warrant the identification of additional immunosuppressive pathways. V domain immunoglobulin suppressor of T cell activation (VISTA) plays a critical role in antitumor immunity and is a valuable target in cancer immunotherapy.

Methods

Here, we used single-cell RNA-seq to analyze the gene expression levels of 14897 cells from a breast cancer sample and its paired 7,320 normal cells. Then, we validated the protein expression of immune checkpoint molecules (VISTA, PD-1, PD-L1, TIGIT, TIM3, and LAG3) in 324 human breast cancer samples by immunohistochemistry and quantitative immunofluorescence (QIF) approaches.

Results

Single cell RNA-seq results show a higher level of immune checkpoint VISTA expression in breast cancer tissue compared to adjacent normal tissue. We also found that VISTA expressed highest in breast cancer tissue than other immune-checkpoints. Immunohistochemical results showed that VISTA was detected with a membranous/cytoplasmic staining pattern in intratumoral immune cells and breast cancer cells. Additionally, VISTA was positively correlated with pathological grade, lymph node status and the levels of PD-1 according to the chi-square test or Fisher’s test. Furthermore, VISTA expression was higher in CD68+ tumor-associated macrophages (TAMs) than in CD4+ T cells, CD8+ cytotoxic T cells or CD20+ B cells.

Conclusions

These findings therefore support the immunoregulatory role of VISTA in breast cancer and indicate that targeting VISTA may benefit breast cancer immunotherapy.

Structure and Functional Binding Epitope of V-domain Ig Suppressor of T Cell Activation

V-domain immunoglobulin (Ig) suppressor of T cell activation (VISTA) is an immune checkpoint protein that inhibits the T cell response against cancer. Similar to PD-1 and CTLA-4, a blockade of VISTA promotes tumor clearance by the immune system. Here, we report a 1.85 Å crystal structure of the elusive human VISTA extracellular domain, whose lack of homology necessitated a combinatorial MR-Rosetta approach for structure determination. We highlight features that make the VISTA immunoglobulin variable (IgV)-like fold unique among B7 family members, including two additional disulfide bonds and an extended loop region with an attached helix that we show forms a contiguous binding epitope for a clinically relevant anti-VISTA antibody. We propose an overlap of this antibody-binding region with the binding epitope for V-set and Ig domain containing 3 (VSIG3), a purported functional binding partner of VISTA. The structure and functional epitope presented here will help guide future drug development efforts against this important checkpoint target.

VISTA: an immune regulatory protein checking tumor and immune cells in cancer immunotherapy

VISTA (V-domain immunoglobulin suppressor of T cell activation) is a well-established immune regulatory receptor. However, pre-clinical investigations indicated more complicated influences of VISTA on cancer immunity than previously recognized. Here, we review the current knowledge on the therapeutic phenotypes and molecular mechanisms that underlie the contradictory roles of VISTA in checking anti-cancer immune responses. Furthermore, we highlight the potential indeterminacy of VISTA-targeted strategies in cancer immunotherapy, with in silico analyses. In fact, VISTA functions like a homeostatic regulator that actively normalizes immune responses. Thus, the regulatory role of VISTA in anti-cancer immunity remains to be fully elucidated.

VISTA: Coming of age as a multi-lineage immune checkpoint

The immune response is governed by a highly complex set of interactions among cells and mediators. T cells may be rendered dysfunctional by the presence of high levels of antigen in the absence of co-stimulation while myeloid cells may be programmed towards an immunosuppressive state that promotes cancer growth and metastasis while deterring tumor immunity. In addition, inhibitory programs driven by immune checkpoint regulators dampen anti-tumor immunity. The ideal cancer immunotherapy treatment will improve both cross-priming in the tumor microenvironment and relieve suppression by the inhibitory checkpoints. Recently, blockade of programmed cell death 1 (PD-1) and cytotoxic T lymphocyte antigen 4 (CTLA-4) has elicited impressive results, but not in all patients, so additional targets are under investigation. V-set immunoglobulin domain suppressor of T cell activation (VISTA) is a novel immunoregulatory receptor that is broadly expressed on cells of the myeloid and lymphoid lineages, and is frequently implicated as a poor prognostic indicator in multiple cancers. Importantly, antibody targeting of VISTA uniquely engages both innate and adaptive immunity. This, combined with the expression of VISTA and its non-redundant activities compared to other immune checkpoint regulators, qualifies VISTA to be a promising target for improving cancer immunotherapy.