V-domain Ig Suppressor Of T Cell Activation Expression Research Articles

Surface Immune Checkpoints as Potential Biomarkers in Physiological Pregnancy and Recurrent Pregnancy Loss.

Due to the genetic diversity between the mother and the fetus, heightened control over the immune system during pregnancy is crucial. Immunological parameters determined by clinicians in women with idiopathic recurrent spontaneous abortion (RSA) include the quantity and activity of Natural Killer (NK) and Natural Killer T (NKT) cells, the quantity of regulatory T lymphocytes, and the ratio of pro-inflammatory cytokines, which indicate imbalances in Th1 and Th2 cell response. The processes are controlled by immune checkpoint proteins (ICPs) expressed on the surface of immune cells. We aim to investigate differences in the expression of ICPs on T cells, T regulatory lymphocytes, NK cells, and NKT cells in peripheral blood samples collected from RSA women, pregnant women, and healthy multiparous women. We aim to discover new insights into the role of ICPs involved in recurrent pregnancy loss. Peripheral blood mononuclear cells (PBMCs) were isolated by gradient centrifugation from blood samples obtained from 10 multiparous women, 20 pregnant women (11-14th week of pregnancy), and 20 RSA women, at maximum of 72 h after miscarriage. The PBMCs were stained for flow cytometry analysis. Standard flow cytometry immunophenotyping of PBMCs was performed using antibodies against classical lymphocyte markers, including CD3, CD4, CD8, CD56, CD25, and CD127. Additionally, ICPs were investigated using antibodies against Programmed Death Protein-1 (PD-1, CD279), T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3, CD366), V-domain Ig suppressor of T cell activation (VISTA), T cell immunoglobulin and ITIM domain (TIGIT), and Lymphocyte activation gene 3 (LAG-3). We observed differences in the surface expression of ICPs in the analyzed subpopulations of lymphocytes between early pregnancy and RSA, after miscarriage, and in women. We noted diminished expression of PD-1 on T lymphocytes (p = 0.0046), T helper cells (CD3CD4 positive cells, p = 0.0165), T cytotoxic cells (CD3CD8 positive cells, p = 0.0046), T regulatory lymphocytes (CD3CD4CD25CD127 low positive cells, p = 0.0106), and NKT cells (CD3CD56/CD16 positive cells, p = 0.0438), as well as LAG-3 on lymphocytes T (p = 0.0225) T helper, p = 0.0426), T cytotoxic cells (p = 0.0458) and Treg (p = 0.0293), and cells from RSA women. Impaired expression of TIM-3 (p = 0.0226) and VISTA (p = 0.0039) on CD8 cytotoxic T and NK (TIM3 p = 0.0482; VISTA p = 0.0118) cells was shown, with an accompanying increased expression of TIGIT (p = 0.0211) on NKT cells. The changes in the expression of surface immune checkpoints indicate their involvement in the regulation of pregnancy. The data might be utilized to develop specific therapies for RSA women based on the modulation of ICP expression.

Comparison of PD-L1, VISTA, LAG-3, and GAL-3 Expressions and Their Relationships to Mismatch Repair Protein and p53 Expression in 529 Cases of Endometrial Carcinoma.

The aim of this study is to evaluate the expressions of programmed death-ligand 1 (PD-L1), V-domain Ig suppressor of T-cell activation (VISTA), lymphocyte activation gene-3 (LAG-3), and galectin-3 (GAL-3), in mismatch repair-deficient (MMRd)/MMR-proficient and abnormal p53 expressing endometrial carcinomas and their relationship with clinical-histopathological features. Patients who underwent surgery for endometrial carcinoma between January 2008 and December 2018 were included in the study. Immunohistochemical analysis of MLH1, PMS2, MSH2, MSH6, p53, PD-L1, VISTA, LAG-3, and GAL-3 was performed on the tissue samples of microarray. A total of 529 patients were included. MMRd and p53-mutant tumors accounted for 31.5% and 11.5% of cases, respectively. PD-L1 and LAG-3 expressions in the MMRd and p53-mutant groups were higher than in the MMR-proficient group (P < 0.001). GAL-3 expression in the MMR-proficient group was statistically higher than in the MMRd and p53-mutant groups (P < 0.001). Mean age, grade, International Federation of Gynecology and Obstetrics stage, lymphovascular invasion, and lymph node metastasis were significantly higher in the p53-mutant group (P < 0.001). In the group with PD-L1 expression, nonendometrioid histologic type, tumor grade, and lymphovascular invasion were significantly higher (P < 0.001). Tumor grade, lymphovascular invasion, lymph node metastasis, and microcystic, elongated and fragmented pattern of invasion were significantly higher in the group with high VISTA expression (P < 0.05). Tumor grade was significantly higher in the group with LAG-3 expression (P < 0.001). Immunohistochemically determined subgroups and PD-L1, VISTA, LAG-3, and GAL-3 expression levels may be useful indicators of molecular features, and clinical outcomes also may have important implications for the development of targeted therapies in endometrial carcinoma.

Expression of VISTA regulated via IFN-γ governs endogenous T-cell function and exhibits correlation with the efficacy of CD19 CAR-T cell treated B-malignant mice

BackgroundDespite continuous improvements in the new target and construction of chimeric antigen receptor (CAR)-T, relapse remains a significant challenge following CAR-T therapy. Tumor microenvironment (TME) strongly correlates with the efficacy...

Abstract PO3-24-02: Molecular characterization and therapeutic approach for VISTA+ triple-negative breast cancers

Abstract Introduction: Current FDA-approved immunotherapeutics for triple-negative breast cancer are only available for a subset of patients, highlighting the need to develop improved immune-targeting strategies. VISTA (V-domain Ig suppressor of T cell activation) is a single-pass transmembrane immune checkpoint receptor that is an emerging clinical target for cancer immunotherapy. It is expressed widely on lymphoid and myeloid cells in healthy individuals, is commonly expressed on cells of the tumor microenvironment and can be abnormally upregulated on tumor cells in a wide variety of tumors. Although VISTA confers quiescence to naïve T cells, molecular mechanisms responsible for this effect remain unclear. Also, the effects of VISTA expression on tumor cells remains poorly defined. Methods: Multi-omic profiling was performed in human breast cancer cells lines to determine immune regulatory genes controlled by growth factor stimulation. Human triple-negative breast cancer tumor specimens (N=248) were examined by immunohistochemistry for expression of VISTA, PDL1, PD1 and FoxP3. VISTA expression was engineered into human and mouse triple-negative breast cancer cell lines and growth metrics were characterized in vitro and in immunocompetent (syngeneic) and immunodeficient (xenograft) mouse tumor models. Membrane receptor trafficking and localization of EGFR was performed in human TNBC cells lines expressing VISTA and VISTA mutants. Proximity biotinylation identified protein partners that interacted with VISTA’s intracellular domain. Deletion mutagenesis was performed to identify motifs required for biochemical interactions between VISTA and clathrin adaptor proteins. Clathrin adapter localization was examined in WT and VISTA knock-out cell lines. Cytokine response, clathrin adaptor localization and tumor growth kinetics were measured in TNBC cell lines expressing VISTA or VISTA mutants. Results: A class of human triple-negative breast cancers were identified with high VISTA expression, low tumor infiltrating lymphocytes and low proliferative index (8-20% of all TNBCs). Tumor models demonstrated that enforced expression of VISTA in tumor cells caused growth suppression, even in the absence of an immune system. This effect was mapped to the cytoplasmic domain of VISTA, which lacks defined signaling domains. Through biochemical approaches, the clathrin-adaptor molecules NUMB and GULP1 were found in complex with a VISTA intracellular NPGF motif. This motif sequestered NUMB at early endosomes, resulting in diminished NUMB recycling for EGFR endocytosis, thereby causing growth suppression. VISTA impaired NUMB recycling by blocking Rab11 effector complex formation. VISTA NPGF mutations did not disrupt cytokine secretion in mixed lymphocyte assays. VISTA-targeted antibodies did not disrupt NUMB sequestration. VISTA+ tumors were selectively sensitive to VISTA-blocking antibodies. Conclusions: VISTA+ TNBC have distinct features including slower proliferative index and increased sensitivity to VISTA-blocking antibodies. This work identifies mechanisms by which VISTA enforces a quiescent cellular state by sequestering clathrin adapter proteins away from sites of endocytosis in cancer cells. This is the first description of intracellular molecular mechanisms controlled by VISTA’s intracellular tail. It may inform features of the VISTA-dependent immune checkpoint that could be exploited to improve anti-tumor immunity. Citation Format: Yan Zhao, Fatima Charles, Andrew Lipchik, Yan Peng, James Ford, Melinda Telli, Song Zhang, Allison Kurian, Michael Snyder, Joshua Gruber. Molecular characterization and therapeutic approach for VISTA+ triple-negative breast cancers [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-24-02.

Expression patterns of novel immunotherapy targets in intermediate- and high-grade lung neuroendocrine neoplasms

BackgroundAdvancements in immunotherapeutic approaches only had a modest impact on the therapy of lung neuroendocrine neoplasms (LNENs). Our multicenter study aimed to investigate the expression patterns of novel immunotherapy targets in intermediate- and high-grade LNENs.MethodsThe expressions of V-domain Ig suppressor of T cell activation (VISTA), OX40L, Glucocorticoid-induced TNF receptor (GITR), and T cell immunoglobulin and mucin domain 3 (TIM3) proteins were measured by immunohistochemistry in surgically resected tumor samples of 26 atypical carcinoid (AC), 49 large cell neuroendocrine lung cancer (LCNEC), and 66 small cell lung cancer (SCLC) patients. Tumor and immune cells were separately scored.ResultsTumor cell TIM3 expression was the highest in ACs (p < 0.001), whereas elevated tumor cell GITR levels were characteristic for both ACs and SCLCs (p < 0.001 and p = 0.011, respectively). OX40L expression of tumor cells was considerably lower in ACs (vs. SCLCs; p < 0.001). Tumor cell VISTA expression was consistently low in LNENs, with no significant differences across histological subtypes. ACs were the least immunogenic tumors concerning immune cell abundance (p < 0.001). Immune cell VISTA and GITR expressions were also significantly lower in these intermediate-grade malignancies than in SCLCs or in LCNECs. Immune cell TIM3 and GITR expressions were associated with borderline prognostic significance in our multivariate model (p = 0.057 and p = 0.071, respectively).ConclusionsLNEN subtypes have characteristic and widely divergent VISTA, OX40L, GITR, and TIM3 protein expressions. By shedding light on the different expression patterns of these immunotherapy targets, the current multicenter study provides support for the future implementation of novel immunotherapeutic approaches.

H-VISTA Immunohistochemistry Score Is Associated with Advanced Stages in Cutaneous and Ocular Melanoma.

Melanoma represents a public health issue. One of the biggest goals of current research is to develop new therapeutic options for patients affected by this aggressive tumor. We conducted a retrospective study including 105 patients diagnosed with cutaneous and ocular melanoma, with stages varying from pT1a to pT4b and pT4e, respectively, and we performed immunohistochemistry reactions with the new potential prognostic marker, VISTA (V-domain Ig suppressor of T cell activation). We quantified the expression by applying the H-score adapted for VISTA and divided the patients, based on the median value, into groups that presented high, low, and negative expression. Therefore, we obtained 65 cases with positive expression for cutaneous melanoma and 8 cases with positive expression for ocular melanoma. Forty-one cases presented high expression in cutaneous melanoma and three cases presented high expression in ocular melanoma. In cutaneous melanoma, analytic statistics showed that VISTA expression was associated with a high Breslow index, high mitotic count, high Ki67 expression, and advanced clinicopathological stage. The majority of ocular melanoma cases demonstrating a positive reaction were classified as stage pT3, whereas earlier stages showed a negative reaction. Our findings underscore a significant correlation between VISTA expression and key prognostic factors in melanoma. Looking ahead, the prospect of future randomized studies holds promise in corroborating the clinical relevance of our findings. By further elucidating the intricate relationship between VISTA expression and melanoma progression, new treatment strategies could be found, improving patient outcomes in this challenging neoplasm.

Abstract 1518: Understanding the role of VISTA in regulating T cells function and the therapeutic potential of blocking VISTA in triple negative breast cancer

Abstract Immune checkpoint inhibitors (ICIs) targeting immune modulatory molecules have been widely used and have shown therapeutic efficacy in treating multiple malignancies in the last decade. However, in triple-negative breast cancer (TNBC), only around 5 % of patients showed a durable response to ICIs. While the response rates were increased up to 10% by combining ICIs with conventional chemotherapy, the majority of the patients did not respond to the treatment. Thus, there is a need to improve our understanding of the mechanism underlying unequal response to ICIs in TNBC and develop/discover new treatments to improve patient outcomes. The lack of response to ICIs has been attributed to the increased infiltration of immunosuppressive cells (including MDSCs, neutrophils and TAMs), as well as the presence of additional immune checkpoint receptors/ligands that may further suppress cytotoxic T cells (CD8+ T cells) in the tumor microenvironment (TME). V-domain Ig suppressor of T-cell activation (VISTA) is one of the immune checkpoint molecules attracting increasing attention in the context of anti-tumor immunity due to its broad expression across various cancer types and increased expression upon development of immune checkpoint resistance. However, the role of VISTA in the anti-tumor immune response and its therapeutic potential in TNBC remains unclear. In our study, we observed that VISTA is expressed in TNBC patients, with higher expression in neutrophils and macrophages. In the Py230 murine breast cancer model, VISTA expression increased upon paclitaxel (PTX), anti-PD-L1 and paclitaxel combined with anti-PD-L1 treatment compared to the control group, suggesting its potential role as a resistance mechanism in further inhibiting T cells. In the Py230 model, VISTA blockade increased the infiltration and activation of CD8+ T cells, as evidenced by the higher number of CD8+ T cells, increased CD69+CD8+ T cells, and Granzyme B production, indicating that VISTA blockade improved CD8+ T cells mediated anti-tumor immunity. To functionally test the role of VISTA, we stimulated CD8+ T cells and co-cultured them with naïve macrophages or tumor educated macrophages in the presence or absence of VISTA blocking antibody. Tumor-educated macrophages showed increased immunosuppressive activity which is abrogated with VISTA blockade. Moreover, we found that the immunosuppressive effect of macrophages on T cell activation needs direct cell interaction between VISTA on macrophages and T cells. In conclusion, this study shows the mechanism of action of VISTA in the regulation of T cells mediated anti-tumor immune response, and provides the rationale for blocking VISTA in TNBC. Citation Format: Maidinaimu Abudula, Yuliana Astuti, Meirion Raymant, Teifion Luckett, Patrick Freeman, Michael Schmid, Ainhoa Mielgo Iza. Understanding the role of VISTA in regulating T cells function and the therapeutic potential of blocking VISTA in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1518.

Abstract B027: Molecular characterization and therapeutic approaches for VISTA+ triple-negative breast cancers

Abstract Introduction: VISTA (V-domain Ig suppressor of T cell activation) is a single-pass transmembrane immune checkpoint receptor that is an emerging clinical target for cancer immunotherapy. Although VISTA confers quiescence to naïve T cells, molecular mechanisms responsible for this effect remain unclear. Also, the effects of VISTA expression on tumor cells remains poorly defined. Methods: Multi-omic profiling was performed in human breast cancer cells lines to determine immune regulatory genes. Human triple-negative breast cancers (N=248) were examined by immunohistochemistry for expression of VISTA, PDL1, PD1 and FoxP3. VISTA expression was engineered into human and mouse triple-negative breast cancer cell lines and growth was characterized in vitro and in mouse models. Membrane receptor trafficking and localization of EGFR and clathrin adapters was performed in cells expressing VISTA, VISTA mutants and VISTA knockouts. Proximity biotinylation identified protein partners that interacted with VISTA’s intracellular domain. Deletion mutagenesis was performed to identify functional VISTA cytoplasmic motifs. Cytokine response and tumor growth kinetics were measured in TNBC mouse models expressing VISTA or VISTA mutants. Results: A class of human triple-negative breast cancers were identified with high VISTA expression, low tumor infiltrating lymphocytes and low proliferative index (8-20% of all TNBCs). Tumor models demonstrated that enforced expression of VISTA in tumor cells caused growth suppression, even in the absence of an immune system. This effect was mapped to the cytoplasmic domain of VISTA, which lacks defined signaling domains. Through biochemical approaches, the clathrin-adaptor molecules NUMB and GULP1 were found in complex with a VISTA intracellular NPGF motif. This motif sequestered NUMB at early endosomes, resulting in diminished NUMB recycling for EGFR endocytosis, thereby causing growth suppression. VISTA impaired NUMB recycling by blocking Rab11 effector complex formation. VISTA NPGF mutations did not disrupt cytokine secretion in mixed lymphocyte assays. VISTA-targeted antibodies did not disrupt NUMB sequestration. VISTA+ tumors were selectively sensitive to VISTA-blocking antibodies. Conclusions: VISTA+ TNBC have distinct features including slower proliferative index and increased sensitivity to VISTA-blocking antibodies. This work identifies mechanisms by which VISTA enforces a quiescent cellular state by sequestering clathrin adapter proteins away from sites of endocytosis in cancer cells. This is the first description of intracellular molecular mechanisms controlled by VISTA’s intracellular tail. It may inform features of the VISTA-dependent immune checkpoint that could be exploited to improve anti-tumor immunity. Integration of these findings with ongoing VISTA clinical trials will be discussed. Citation Format: Joshua Gruber, Yan Zhao, Fatima Charles, Priyanka Reddy, Kristina Paul, Virginia Ezenwa, Marisa Juntilla, Idit Sagiv-Barfi, Yan Peng, Song Zhang, Allison Kurian, Michael Snyder. Molecular characterization and therapeutic approaches for VISTA+ triple-negative breast cancers [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr B027.

VISTA as a prospective immune checkpoint in gynecological malignant tumors: A review of the literature.

V-domain Ig suppressor of T cell activation (VISTA), encoded by the human VSIR gene, is a B7 family checkpoint homologous to the programmed death-Ligand 1 sequence. In gynecologic malignancies, VISTA is abnormally expressed and regulates the tumor immune microenvironment, causing a high upregulation of VISTA expression in T-cells and myeloid cells in the tumor microenvironment and promoting tumor proliferation, progression, and immune tolerance. Here, we review the research progress of VISTA in ovarian, cervical, and endometrial cancers through its structure and immunomodulatory mechanism. The comprehensive study of VISTA is expected to improve the current problem of poor immunotherapeutic effects and provide new ideas for immune therapy in patients with gynecologic tumors.

VISTA blockade alleviates immunosuppression of MDSCs in oral squamous cell carcinoma

V-domain Ig suppressor of T-cell activation (VISTA) is a novel immune checkpoint regulator that can inhibit T cell-mediated antitumor immunity. Although the use of anti-VISTA monoclonal antibody has demonstrated encouraging outcomes in the therapy of various malignancies, its specific impact and underlying mechanisms in oral squamous cell carcinoma (OSCC) remain to be explored. In this work, we analyzed human OSCC tissue microarrays, human peripheral blood mononuclear cells, and immunocompetent transgenic mouse models to investigate the relationship between high VISTA expression and markers of myeloid-derived immunosuppressive cells (MDSCs; CD11b, CD33, Arginase-1), tumor-associated macrophages (CD68, CD163, CD206), and T cell function (CD8, PD-L1, Granzyme B). In OSCC, we discovered that VISTA was highly expressed and stably expressed in MDSCs. Furthermore, we established a mouse OSCC orthotopic xenograft tumor model to investigate the impact of VISTA blockade on the tumor microenvironment. We found that VISTA blockade reduces the immunosuppressive microenvironment and delays tumor growth. This is achieved by suppressing the quantity and function of MDSCs while boosting the function of tumor-infiltrating T cells. Our research indicated that VISTA expressed by MDSCs has a crucial function in the progression of OSCC and that VISTA blockade therapy is a promising immune checkpoint blockade therapy.

Positive TIGIT and VISTA Expression Predict Worse Prognosis in Cervical Cancer Patients Treated with (Chemo)Radiotherapy

Immune checkpoint inhibitors combined with (chemo)radiotherapy could be an attractive treatment strategy for patients with cervical cancer (CC), but the expression of some immune checkpoint proteins in cervical cancer and their impact on patient survival remains largely unknown. Here, we investigated the predictive value of T cell immunoreceptor with Ig and ITIM domain (TIGIT), V-domain Ig suppressor of T cell activation (VISTA), and lymphocyte-activation gene-3 (LAG-3) expression in pathological tissues of CC patients treated with (chemo)radiotherapy. We enrolled 175 CC patients who received (chemo)radiotherapy and collected their pre-treatment tumor tissue sections for the immunohistochemical stain of TIGIT, VISTA, and LAG-3. The Kaplan-Meier method was used to calculate progression-free survival (PFS) and overall survival (OS) after (chemo)radiotherapy. Univariate and multivariate COX proportional hazards regression models were employed to analyze potential risk factors for patient survival. Kaplan-Meier survival analyses showed that the PFS and OS of patients with positive expression of TIGIT and VISTA were significantly shorter than those patients with negative expression of the proteins (all p<0.05). However, we did not reach the same conclusion in the analysis of LAG-3 (both p>0.05). Univariate COX regression analysis showed that the positive expression of TIGIT and VISTA are related to poor PFS and OS (both HR>1.0 and p<0.05). Multivariate COX regression analysis showed that TIGIT positive and VISTA positive patients have shorter PFS and OS (both HR>1.0 and p<0.05). There is no significant correlation between LAG-3 expression and PFS or OS in these CC patients treated with (chemo)radiotherapy. We revealed that positive TIGIT and VISTA expression could predict worse prognosis in cervical cancer patients treated with (chemo)radiotherapy, which may help to refine the treatment strategies of combining immune checkpoint inhibitors and radiotherapy.

VISTA expression on cancer-associated endothelium selectively prevents T-cell extravasation.

Cancers evade T-cell immunity by several mechanisms such as secretion of anti-inflammatory cytokines, downregulation of antigen presentation machinery, upregulation of immune checkpoint molecules, and exclusion of T cells from tumor tissues. The distribution and function of immune checkpoint molecules on tumor cells and tumor-infiltrating leukocytes is well established, but less is known about their impact on intratumoral endothelial cells. Here, we demonstrated that V-domain Ig suppressor of T-cell activation (VISTA), a PD-L1 homologue, was highly expressed on endothelial cells in synovial sarcoma, subsets of different carcinomas, and immune-privileged tissues. We created an ex vivo model of the human vasculature and demonstrated that expression of VISTA on endothelial cells selectively prevented T-cell transmigration over endothelial layers, under physiological flow conditions, whereas it does not affect migration of other immune cell types. Furthermore, endothelial VISTA correlated with reduced infiltration of T cells and poor prognosis in metastatic synovial sarcoma. In endothelial cells, we detected VISTA on the plasma membrane and in recycling endosomes, and its expression was upregulated by cancer cell-secreted factors in a VEGF-A-dependent manner. Our study reveals that endothelial VISTA is upregulated by cancer-secreted factors and that it regulates T-cell accessibility to cancer and healthy tissues. This newly identified mechanism should be considered when using immunotherapeutic approaches aimed at unleashing T cell-mediated cancer immunity.

Vista of the Future: Novel Immunotherapy Based on the Human V-Set Immunoregulatory Receptor for Digestive System Tumors.

While gastrointestinal tumors remain a multifactorial and prevalent group of malignancies commonly treated surgically in combination with chemotherapy and radiotherapy, advancements regarding immunotherapeutic approaches continue to occur. Entering a new era of immunotherapy focused on overcoming resistance to preceding therapies caused the emergence of new therapeutic strategies. A promising solution surfaces with a V-domain Ig suppressor of T-cell activation (VISTA), a negative regulator of a T-cell function expressed in hematopoietic cells. Due to VISTA's ability to act as both a ligand and a receptor, several therapeutic approaches can be potentially developed. A broad expression of VISTA was discovered on various tumor-growth-controlling cells, which proved to increase in specific tumor microenvironment (TME) conditions, thus serving as a rationale behind the development of new VISTA-targeting. Nevertheless, VISTA's ligands and signaling pathways are still not fully understood. The uncertain results of clinical trials suggest the need for future examining inhibitor agents for VISTA and implicating a double immunotherapeutic blockade. However, more research is needed before the breakthrough can be achieved. This review discusses perspectives and novel approaches presented in the current literature. Based on the results of the ongoing studies, VISTA might be considered a potential target in combined therapy, especially for treating gastrointestinal malignancies.

VISTA+/CD8+ status correlates with favorable prognosis in Epithelial ovarian cancer.

Immunotherapy by blocking immune checkpoint regulators has emerged as a new targeted therapy for some cancers. Among them V-domain Ig suppressor of Tcell activation (VISTA) which is identified as a novel checkpoint regulator in ovarian cancer. This study aimed to investigate the VISTA role in Epithelial ovarian cancer (EOC), and its relationship with tumor-infiltrating lymphocytes (TILs) markers and its prognostic value. The expression of VISTA, CD3, CD8, CD4, FOXP3, and CD56 was assessed in 168 EOC tissue microarrays (TMA) by immunohistochemistry (IHC). In addition, associations between VISTA, TILs, clinicopathological variables, and overall survival (OS) were analyzed. VISTA expression in IGRov1 cells, as well as in PBMC of EOC patient, was evaluated by western blot. VISTA expression was detected in 64,28% of tissues, among which 42.3% were positive for tumor cells (TCs), and 47,9% were positive for immune cells (ICs). In univariate analysis, VISTA expression was significantly associated with a high density of TILs:CD3+ (p = 0,001), CD4+ (p = 0,002) and CD8+ (p≤0,001), in ICs but not in TCs. In terms of OS, multivariate analysis showed a significant association between the high density of CD8+ TILs and VISTA positive staining in ICs (p = 0,044), but not in TCs (p = 0,108). Kaplan-Meier curves demonstrated no correlation between VISTA expression and prolonged OS in both ICs (p = 0,841) and TCs (p = 0,090). Classification of EOC tumor microenvironment based on VISTA and CD8+TILs expression, demonstrated four immune subtypes: VISTA+/CD8+, VISTA+/CD8-, VISTA-/CD8+ and VISTA-/CD8-. The dual positive VISTA+/CD8+ subtype was significantly associated with prolonged OS in both TCs and ICs (p = 0,012 and p≤0,01, respectively), whereas patients with VISTA+/CD8- had the worst OS. Our results showed that VISTA is highly expressed in the IGRov1 cell line and LT-CD8 from a patient with EOC. Our results highlighted the association of VISTA expression and CD8+ TILs in EOC, with prolonged OS in patients with VISTA+/CD8+ and proposed VISTA as a potential immunotherapeutic target in EOC.

A preliminary study on the role of V-domain Ig suppressor of T cell activation in juvenile idiopathic arthritis

To study the expression of V-domain Ig suppressor of T cell activation (VISTA) in peripheral blood of children with juvenile idiopathic arthritis (JIA) and its role in the pathogenesis of JIA. In this prospective study, peripheral blood was collected from 47 children with different subtypes of JIA and 10 healthy children. Flow cytometry was used to measure the expression levels of VISTA, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α) on CD14+ mononuclear cells, CD4+ T lymphocytes, and CD8+ T lymphocytes. The children with JIA had a significantly lower expression level of VISTA than the healthy children (P<0.05). There was a significant difference in the expression of VISTA between the children with different subtypes of JIA, with the lowest expression level in those with systemic JIA (P<0.05). There was also a significant difference in the expression of VISTA between different immune cells, with a significantly higher expression level on the surface of monocytes (P<0.05). Correlation analysis showed that VISTA was negatively correlated with the expression of IFN-γ and TNF-α on CD4+ T cells (r=-0.436 and -0.382 respectively, P<0.05), CD8+ T cells (r=-0.348 and -0.487 respectively, P<0.05), and CD14+ mononuclear cells (r=-0.582 and -0.603 respectively, P<0.05). The insufficient expression of VISTA may be associated with the pathogenesis of JIA, and enhancing the immunomodulatory effect of VISTA might be one option for the treatment of JIA in the future.

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.

VISTA H-Score Is Significantly Associated with a 5-Year DFS Rate in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer in the world. Despite its prevalence, it is often recognized in advanced stages (III or IV) when it has already spread to local lymph nodes. In this study, we investigate the V-domain Ig suppressor of T cell activation (VISTA) as a potential prognostic factor in OSCC. Tissue samples were collected from 71 oral squamous cell carcinoma patients to determine protein expression levels (using immunochemistry and the semi-quantitative H-score method). Moreover, RT-qPCR was additionally performed in 35 patients. Clinical factors in our cohort study had no impact on VISTA expression. However, VISTA expression is largely correlated with Il-33 levels in tumor cells and lymphocytes and with PD-L1 in tumor cells. The impact of VISTA expression on overall survival (OS) is rather limited, but in the case of a 5-year survival rate, a significant association has been proven. VISTA seems to be a rather weak clinicopathological marker but needs further evaluation in the context of survival. In addition, the potential of VISTA combination with Il-33 or PD-L1 should be further investigated in OSCC.

Clinical significance of immune checkpoint proteins in HPV-infected cervical cancer

ObjectiveTo investigate T cell immunoreceptor with Ig and ITIM domain (TIGIT), V-domain Ig suppressor of T cell activation (VISTA), and lymphocyte-activation gene-3 (LAG-3) expression in pathological tissue of human papillomavirus (HPV)-infected cervical cancer (CC) patients and their relationship with patient prognosis. MethodsClinical data of 175 patients with HPV-infected CC were collected retrospectively. Tumor tissue sections were stained immunohistochemically for TIGIT, VISTA, and LAG-3. The Kaplan-Meier method calculated patient survival. Univariate and multivariate Cox proportional hazards models analyzed all potential risk factors for survival. ResultsWhen combined positive score (CPS)= 1 was used as the cut-off value, the Kaplan-Meier survival curve showed that the progression-free survival (PFS) and overall survival (OS) of patients with positive expression of TIGIT and VISTA are shorter (both p < 0.05). Univariate COX regression analysis showed that the positive expression of TIGIT and VISTA are related to patient PFS and OS (both HR>1.0 and p < 0.05). Multivariate COX regression analysis showed that TIGIT-positive patients had shorter OS and VISTA-positive patients had shorter PFS (both HR>1.0 and p < 0.05). There is no significant correlation between LAG-3 expression and PFS or OS. When CPS= 10 was used as the cut-off value, Kaplan-Meier survival curve showed that TIGIT-positive patients had shorter OS (p = 0.019). Univariate COX regression analysis showed that TIGIT-positive expression was associated with the OS of patients (HR=2.209, CI: 1.118–4.365, p = 0.023). However, multivariate COX regression analysis showed that TIGIT expression was not associated significantly with OS. There was no significant correlation between VISTA and LAG-3 expression and PFS or OS. ConclusionTIGIT and VISTA are associated closely with HPV-infected CC prognosis and are effective biomarkers.

Comprehensive Transcriptomic Analysis of VISTA in Acute Myeloid Leukemia: Insights into Its Prognostic Value.

The V-domain Ig suppressor of T-cell activation (VISTA) has been recognized as a critical negative regulator of antitumor immune response and is gaining growing interest as a potential pharmacological target in immunotherapy. This molecule is highly expressed in hematopoietic stem cells and myeloid compartment, and it has been found upmodulated in acute myeloid leukemia (AML). However, VISTA-associated immune features are relatively unexplored in myeloid malignancies. Herein, we aimed to explore whether this immune checkpoint regulator could play a role in the generation of an immune escape environment in AML patients. We characterized VISTA mRNA expression levels in leukemia cell lines and in large publicly available cohorts of specimens from bone marrow of healthy individuals and AML patients at diagnosis by deploying bulk and single-cell RNA sequencing. We also defined the correlations with leukemia-associated burden using results of whole-exome sequencing of AML samples at disease onset. We showed that VISTA expression linearly increased across the myeloid differentiation tree in normal hematopoiesis. Accordingly, its transcript was highly enriched in AML cell lines as well as in AML patients at diagnosis presenting with myelomonocytic and monocytic differentiation. A strong correlation was seen with NPM1 mutations regardless of the presence of FLT3 lesions. Furthermore, VISTA expression levels at baseline correlated with disease recurrence in patients with normal karyotype and NPM1 mutations, a subgroup traditionally considered as favorable according to current diagnostic schemes. Indeed, when compared to patients with long-term remission (&gt;5 years after standard chemotherapy regimens), cases relapsing within 2 years from diagnosis had increased VISTA expression in both leukemia and T cells. Our results suggest a rationale for developing VISTA-targeted therapeutic strategies to treat molecularly defined subgroups of AML patients to prevent disease recurrence and treatment resistance.

The Features of Checkpoint Receptor-Ligand Interaction in Cancer and the Therapeutic Effectiveness of Their Inhibition.

To date, certain problems have been identified in cancer immunotherapy using the inhibition of immune checkpoints (ICs). Despite the excellent effect of cancer therapy in some cases when blocking the PD-L1 (programmed death-ligand 1) ligand and the immune cell receptors PD-1 (programmed cell death protein 1) and CTLA4 (cytotoxic T-lymphocyte-associated protein 4) with antibodies, the proportion of patients responding to such therapy is still far from desirable. This situation has stimulated the exploration of additional receptors and ligands as targets for immunotherapy. In our article, based on the analysis of the available data, the TIM-3 (T-cell immunoglobulin and mucin domain-3), LAG-3 (lymphocyte-activation gene 3), TIGIT (T-cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory motif (ITIM) domains), VISTA (V-domain Ig suppressor of T-cell activation), and BTLA (B- and T-lymphocyte attenuator) receptors and their ligands are comprehensively considered. Data on the relationship between receptor expression and the clinical characteristics of tumors are presented and are analyzed together with the results of preclinical and clinical studies on the therapeutic efficacy of their blocking. Such a comprehensive analysis makes it possible to assess the prospects of receptors of this series as targets for anticancer therapy. The expression of the LAG-3 receptor shows the most unambiguous relationship with the clinical characteristics of cancer. Its inhibition is the most effective of the analyzed series in terms of the antitumor response. The expression of TIGIT and BTLA correlates well with clinical characteristics and demonstrates antitumor efficacy in preclinical and clinical studies, which indicates their high promise as targets for anticancer therapy. At the same time, the relationship of VISTA and TIM-3 expression with the clinical characteristics of the tumor is contradictory, and the results on the antitumor effectiveness of their inhibition are inconsistent.