Benign Islet Cells Within Peripancreatic Lymph Nodes: A Potential Diagnostic Pitfall.

The presence of epithelial cells within lymph node parenchyma is typically indicative of a metastatic malignancy. However, there are rare instances in which non-neoplastic epithelial or epithelioid cells may be found within lymph nodes, either due to aberrant embryologic migration, mechanical displacement, or physiological trafficking. These can potentially lead to serious potential diagnostic pitfalls, as when such situations are encountered by surgical pathologists, there is substantial risk of overdiagnosing these as metastatic malignancy. Herein, we describe 2 cases of benign pancreatic islet cells within peripancreatic lymph nodes, and underscore the potential for misdiagnosis of this phenomenon as foci of metastatic well-differentiated neuroendocrine tumor. The benign nature of these intranodal islet cells was supported by: (1) the absence of a well-differentiated neuroendocrine tumor in the entirely submitted concomitant pancreatic resection specimen and (2) the presence of an admixture of insulin and glucagon expressing cells by immunohistochemistry in a distribution characteristic of non-neoplastic pancreatic islets. Both cases were incidental microscopic findings in pancreatic resections for intraductal papillary mucinous neoplasms that were previously biopsied and showed associated microscopic areas of fibrosis and chronic pancreatitis and thus this phenomenon may be related to mechanical displacement from prior injury and/or biopsy.

Retrospective Analyses of PD-L1, LAG-3, TIM-3, OX40L Expressions and MSI Status in Gastroenteropancreatic Neuroendocrine Neoplasms.

We investigated expressions of PD-L1, LAG-3, TIM-3, and OX40L as immune checkpoint proteins, and MSI (repetitive short-DNA-sequences due to defective DNA-repair system) status were analyzed with immunohistochemistry from tissue blocks. Of 83 patients, PD-L1 expression was observed in 18.1% (n = 15) of the patients. None of the patients exhibited LAG-3 expression. TIM-3 expression was 4.9% (n = 4), OX40L was 22.9% (n = 19), and 8.4% (n = 7) of the patients had MSI tumor. A low-to-intermediate positive correlation was observed between PD-L1 and TIM-3 expressions (rho: 0.333, p < 0.01). Although PD-L1 expression was higher in grade 3 NET/NEC, MSI status was prominent in grade 1/2 NET.

Electrochemiluminescence imaging of a membrane carcinoembryonic antigen at single tissue sections.

Histopathological molecular testing of tissue sections is an essential step in tumor diagnosis; however, the commonly used immunohistochemical methods have problems such as low specificity and the subjective bias of the observer. Here, we report an electrochemiluminescence (ECL) imaging method to detect a membrane carcinoembryonic antigen (CEA) at the single tissue sections of cancer patients. By permeabilizing the tissue attached to a glassy carbon electrode, Ru(bpy)32+ tagged at the membrane CEA of the tissue could electrochemically react with TPrA in solution to emit ECL that has near-zero background and an extremely high signal-to-background ratio. Using the established ECL method, the expression differences and distribution characteristics of the CEA protein in the carcinoma and paracancerous tissues of pancreatic ductal carcinoma (PDAC) and lung adenocarcinoma (LUAD) patients are investigated. The images reveal that CEA proteins are mostly distributed in the acini and surrounding areas both in PDAC and LUAD tissues. Therefore, the presented approach could be able to provide a new molecular recognition method for the diagnosis of adenocarcinoma and other tumors.

Immunohistochemical analysis of a panel of cancer stem cell markers and potential therapeutic markers in pancreatic ductal adenocarcinoma.

PURPOSE: Pancreatic Ductal Adenocarcinoma (PDAC) is the most common type of pancreatic malignancies. It is known for its aggressive nature and high mortality rate. This calls for an urgent need of new prognostic and therapeutic markers that can be targeted for personalized treatment of the patient. METHODS: Among 142 patients diagnosed with pancreatic cancers at Aga Khan University Hospital, a total of 62 patients were selected based on their confirmed diagnosis of PDAC. Immunohistochemistry was performed on Formalin-Fixed Paraffin-Embedded (FFPE) sections using selected antibodies (CD44, CD133, L1CAM, HER2, PD-L1, EGFR, COX2 and cyclin D1). All the slides were scored independently by two pathologists as per the set criteria. RESULTS: Expression of all cancer stem cell markers was found to be significantly associated with one or more potential therapeutic markers. CD44 expression was significantly associated with HER2 (p = 0.032), COX2 (p = 0.005) and EGFR expression (p = 0.008). CD133 expression also showed significant association with HER2 (p = 0.036), COX2 (p = 0.004) and EGFR expression (p = 0.018). L1CAM expression was found to be associated with expression of COX2 (p = 0.017). None of the proteins markers showed association with overall survival of the patient. On the other hand, among the clinicopathological characteristics, histological differentiation (p = 0.047), lymphovascular invasion (p = 0.021) and perineural invasion (p = 0.014) were found to be significantly associated with patient's overall survival. CONCLUSION: Internationally, this is the first report that assesses the selected panel of cancer stem cell markers and potential therapeutic targets in a single study and evaluates its combined expression. The study clearly demonstrates association between expression of cancer stem cell markers and therapeutic targets hence paves a way for precision medicine for pancreatic cancer patients.

Deciphering the immunopeptidome in vivo reveals new tumour antigens.

Immunosurveillance of cancer requires the presentation of peptide antigens on major histocompatibility complex class I (MHC-I) molecules1-5. Current approaches to profiling of MHC-I-associated peptides, collectively known as the immunopeptidome, are limited to in vitro investigation or bulk tumour lysates, which limits our understanding of cancer-specific patterns of antigen presentation in vivo6. To overcome these limitations, we engineered an inducible affinity tag into the mouse MHC-I gene (H2-K1) and targeted this allele to the KrasLSL-G12D/+Trp53fl/fl mouse model (KP/KbStrep)7. This approach enabled us to precisely isolate MHC-I peptides from autochthonous pancreatic ductal adenocarcinoma and from lung adenocarcinoma (LUAD) in vivo. In addition, we profiled the LUAD immunopeptidome from the alveolar type 2 cell of origin up to late-stage disease. Differential peptide presentation in LUAD was not predictable by mRNA expression or translation efficiency and is probably driven by post-translational mechanisms. Vaccination with peptides presented by LUAD in vivo induced CD8+ T cell responses in naive mice and tumour-bearing mice. Many peptides specific to LUAD, including immunogenic peptides, exhibited minimal expression of the cognate mRNA, which prompts the reconsideration of antigen prediction pipelines that triage peptides according to transcript abundance8. Beyond cancer, the KbStrep allele is compatible with other Cre-driver lines to explore antigen presentation in vivo in the pursuit of understanding basic immunology, infectious disease and autoimmunity.

Metastatic Patterns of Duodenopancreatic Neuroendocrine Tumors in Patients With Multiple Endocrine Neoplasia Type 1.

Patients with multiple endocrine neoplasia 1 syndrome (MEN1) often develop multifocal duodenopancreatic neuroendocrine tumors (dpNETs). Nonfunctional pancreatic neuroendocrine tumors (PanNETs) and duodenal gastrinomas are the most frequent origins of metastasis. Current guidelines recommend surgery based on tumor functionality, size ≥2 cm, grade or presence of lymph node metastases. However, in case of multiple primary tumors it is often unknown which specific tumor metastasized. This study aims to unravel the relationship between primary dpNETs and metastases in patients with MEN1 by studying endocrine differentiation. First, it was shown that expression of the endocrine differentiation markers ARX and PDX1 was concordant in 18 unifocal sporadic neuroendocrine tumors (NETs) and matched metastases. Thereafter, ARX, PDX1, Ki67 and gastrin expression, and the presence of alternative lengthening of telomeres were determined in 137 microscopic and macroscopic dpNETs and 36 matched metastases in 10 patients with MEN1. ARX and PDX1 H-score clustering was performed to infer relatedness. For patients with multiple metastases, similar intrametastases transcription factor expression suggests that most metastases (29/32) originated from a single NET of origin, while few patients may have multiple metastatic primary NETs. In 6 patients with MEN1 and hypergastrinemia, periduodenopancreatic lymph node metastases expressed gastrin, and clustered with minute duodenal gastrinomas, not with larger PanNETs. PanNET metastases often clustered with high grade or alternative lengthening of telomeres-positive primary tumors. In conclusion, for patients with MEN1-related hypergastrinemia and PanNETs, a duodenal origin of periduodenopancreatic lymph node metastases should be considered, even when current conventional and functional imaging studies do not reveal duodenal tumors preoperatively.

MicroRNA-204-3p inhibits metastasis of pancreatic cancer via downregulating MGAT1.

PURPOSE: We aimed to clarify the relationship between microRNA-204-3p level and clinical indicators in pancreatic cancer patients, and to provide theoretical references for target therapy. METHODS: Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to detect relative levels of microRNA-204-3p and MGAT1 in 60 paired pancreatic cancer tissues and adjacent normal ones. The relationship between microRNA-204-3p level and clinical indicators in pancreatic cancer patients was analyzed. MicroRNA-204-3p overexpression model was established in AsPC-1 and CFPAC-1 cells. Transwell and wound healing assay were carried out to illustrate the influence of microRNA-204-3p on the migratory potential in pancreatic cancer. Lastly luciferase assay and rescue experiments were performed to demonstrate the potential mechanism between microRNA-204-3p and MGAT1. RESULTS: MicroRNA-204-3p was lowly expressed in pancreatic cancer tissues. Low level of microRNA-204-3p predicted high rates of lymphatic metastasis and distant metastasis, as well as poor prognosis in pancreatic cancer patients. Overexpression of microRNA-204-3p inhibited pancreatic cancer cells to migrate in vitro. MicroRNA-204-3p could be targeted by MGAT1 through specific binding sites in the 3'UTR. A negative correlation between MGAT1 and microRNA-204-3p was identified in pancreatic cancer tissues. The interaction between MGAT1 and microRNA-204-3p was responsible for inhibiting metastasis of pancreatic cancer. CONCLUSIONS: MicroRNA-204-3p is closely linked to lymphatic metastasis, distant metastasis and prognosis in pancreatic cancer patients. It inhibits the migratory ability in pancreatic cancer cells via negatively regulating MGAT1 level.

Role of Maspin, CK17 and Ki-67 Immunophenotyping in Diagnosing of Pancreatic Ductal Adenocarcinoma in Endoscopic Ultrasound-Guided Fine Needle Aspiration Cytology.

BACKGROUND AND STUDY AIM: One of the problems in diagnosing pancreatic ductal adenocarcinoma (PDAC) is differentiation between PDAC cells and benign pancreatic tissue cells in cytologic samples. This study aimed to evaluate the usefulness of Maspin, CK17 and Ki-67 immunocytochemistry (ICC) in differentiation between these two groups of cells. MATERIALS AND METHODS: This retrospective study was carried on 80 cases of PDAC and 25 cell blocks of benign pancreatic tissue cells as a control group for evaluation of Maspin, CK17 and Ki-67 ICC. PDAC cases were sampled by endoscopic ultrasound guided fine needle aspiration cytology (EUS-FNAC), while cell blocks of control group were aspirated from benign pancreatic tissues that were obtained from the pancreatic surgically resected specimens. Immunostaining patterns, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of each antibody as well as possible antibody combined panels of these markers in differentiation between the two groups were evaluated. RESULTS: Positive immunoreactivity for Maspin, CK17 and Ki-67 were 92.5%, 80% and 72.5% in PDAC cases, respectively. In contrast to PDAC cases, all the cell blocks of benign pancreatic tissue cells were negative for these markers. Regarding different panels, combined use of Maspin, CK17 and Ki-67 together as a triple test (at least one of them is positive) achieved the highest sensitivity of 98.8%, specificity of 100%, PPV of 100%, NPV of 96.2% and accuracy of 99% in the differentiation between PDAC and benign pancreatic tissue. CONCLUSION: Employing this short panel [Maspin, CK17 and Ki-67] is helpful for better differentiation between PDAC and benign pancreatic tissue.

A limited panel of INSM1 and LEF1 immunostains accurately distinguishes between pancreatic neuroendocrine tumor and solid pseudopapillary neoplasm.

Solid pseudopapillary neoplasm (SPN) and well differentiated pancreatic neuroendocrine tumor (PNET) can show significant cytomorphological overlap. In this study, we evaluated the role of INSM1 and LEF1 immunohistochemical stains in distinguishing between these two tumors. 22 SPN and 25 PNET surgically resected cases were stained for both INSM1 and LEF1. All the 22 cases of SPN showed strong and diffuse nuclear staining for LEF1 (in >95 % of tumor cells), while all 25 PNET were negative for LEF1. All 25 PNET cases were positive for INSM1 (moderate to strong intensity nuclear staining in >50 % of the tumor cells), while all 22 cases of SPN were negative for INSM1. The results of our study show that a limited panel comprising of INSM1 and LEF1 immunostains accurately distinguishes between SPN and PNET.

Clinical Perspective on Proteomic and Glycomic Biomarkers for Diagnosis, Prognosis, and Prediction of Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is known as a highly aggressive malignant disease. Prognosis for patients is notoriously poor, despite improvements in surgical techniques and new (neo)adjuvant chemotherapy regimens. Early detection of PDAC may increase the overall survival. It is furthermore foreseen that precision medicine will provide improved prognostic stratification and prediction of therapeutic response. In this review, omics-based discovery efforts are presented that aim for novel diagnostic and prognostic biomarkers of PDAC. For this purpose, we systematically evaluated the literature published between 1999 and 2020 with a focus on protein- and protein-glycosylation biomarkers in pancreatic cancer patients. Besides genomic and transcriptomic approaches, mass spectrometry (MS)-based proteomics and glycomics of blood- and tissue-derived samples from PDAC patients have yielded new candidates with biomarker potential. However, for reasons discussed in this review, the validation and clinical translation of these candidate markers has not been successful. Consequently, there has been a change of mindset from initial efforts to identify new unimarkers into the current hypothesis that a combination of biomarkers better suits a diagnostic or prognostic panel. With continuing development of current research methods and available techniques combined with careful study designs, new biomarkers could contribute to improved detection, prognosis, and prediction of pancreatic cancer.

MicroRNA-216a targets WT1 expression and regulates KRT7 transcription to mediate the progression of pancreatic cancer-A transcriptome analysis.

Gene expression profiling has been broadly performed in the field of cancer research. This study aims to explore the key gene regulatory network and focuses on the functions of microRNA (miR)-216a in pancreatic cancer (PC). PC datasets GSE15471, GSE16515, and GSE32676 were used to screen the differentially expressed genes (DEGs) in PC. A miRNA microarray analysis and gene oncology analysis suggested miR-216a as an important differentially expressed miRNA in PC. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis suggested that miR-216a and the DEGs are largely enriched on the phosphatidyl inositol 3-kinase/protein kinase B (PI3K/AKT) signaling pathway. miR-216a targeted Wilms Tumor 1 (WT1), while WT1 promoted transcription activity of keratin 7 (KRT7). Upregulation of miR-216a reduced proliferation and invasiveness of PC cells, while further upregulation of WT1 blocked the functions of miR-216a. Silencing of KRT7 diminished the oncogenic role of WT1. The in vitro results were reproduced in vivo. High expression of miR-216a while poor expression of WT1 indicated better prognosis of PC patients. The miR-216a/WT1/KRT7 axis influenced the activity of the PI3K/AKT pathway. To conclude, this study evidenced that miR-216a suppressed WT1 expression and blocked KRT7 transcription, which inactivated the PI3K/AKT signaling and reduced PC progression.

Simple mucinous cyst: another potential cancer precursor in the pancreas? Case report with molecular characterization and systematic review of the literature.

Cystic lesions of the pancreas may range from benign to precursors of pancreatic cancer. Simple mucinous cyst (SMC) is larger than 1 cm, has a gastric-type flat mucinous lining, and minimal atypia without ovarian-type stroma. We report a new case of pancreatic SMC, coupling a systematic review of the English literature mainly focused on their clinic-pathological features. We reviewed 103 cases of SMC in adults (73 women), averaging 57 (range, 26-70) years. The SMCs were located in the body-tail region of the pancreas in 60 (58%) cases, presenting as single cystic lesions in 94% of cases; 43% of patients were asymptomatic. A preoperative fine-needle aspiration of the cyst fluid detected amylase and carcinoembryonic antigen positivity in 71% and 76% of cases, respectively. Patients underwent surgery mostly for suspected malignancy; in 83% of cases, a standard pancreatic resection was performed. Mean SMC size was 4.9 (range, 1.5-12.0) cm. Mucins MUC5AC and MUC6 resulted positive in 77% and 81% of cases performed, respectively, whereas MUC2 was negative in all but one patient. The SMC from our institution was characterized by a KRAS somatic mutation. The diagnosis of SMC should be considered when a solitary pancreatic cyst larger than 1 cm is detected in asymptomatic patients. To establish a correct diagnosis, an extensive histologic/immunohistochemical analysis is essential. The presence of a KRAS mutation highlights that SMC may represent another potential pancreatic cancer precursor.

Expression of Calretinin, Marker of Mesothelial Differentiation, in Pancreatic Ductal Adenocarcinoma: A Potential Diagnostic Pitfall.

OBJECTIVE: Pancreatic ductal adenocarcinoma is one of the most common causes of "peritoneal carcinomatosis" and has an insidious growth pattern. Thus, it falls into the differential diagnosis of other peritoneal malignancies including malignant mesothelioma. Recently, we have encountered an undifferentiated pancreatic carcinoma presenting with peritoneal disease and exhibiting immunoreactivity to calretinin, mimicking mesothelioma. In this study, we explored the incidence of calretinin expression in pancreatic ductal adenocarcinoma. MATERIALS AND METHODS: Calretinin immunohistochemical staining was performed on the tissue microarrays (TMAs), which were created using three 0.6 mm diameter punches per tumor (n=113). Distribution and intensity of expression were evaluated. RESULTS: The TMAs contained 86 well/moderately differentiated and 27 poorly differentiated/undifferentiated carcinomas. Calretinin was positive in nine tumors (8%); six with diffuse and strong staining, three with focal and/or weak staining. The incidence of calretinin expression was 15% in poorly differentiated/undifferentiated carcinomas (vs. 6% in well/moderately differentiated carcinomas, p=0.03). CONCLUSIONS: Pancreatic ductal adenocarcinomas, especially when poorly differentiated/undifferentiated, may be diffusely and strongly positive for calretinin creating a potential diagnostic challenge with malignant mesothelioma. Therefore, caution should be exercised when using this marker to explore a diagnosis of malignant mesothelioma. Tumors expressing calretinin without other mesothelial markers should prompt a careful evaluation of the morphologic and immunohistochemical features to exclude other malignancies. If the diagnosis of pancreatic ductal adenocarcinoma is considered, ductal differentiation can be demonstrated by using additional immunohistochemical markers such as mucin-related glycoproteins (MUC1, MUC5AC) and/or oncoproteins (CEA, B72.3, CA125).

Polyanhydride nanoparticles stabilize pancreatic cancer antigen MUC4ß.

Pancreatic cancer (PC) is one of the most lethal malignancies and represents an increasing and challenging threat, especially with an aging population. The identification of immunogenic PC-specific upregulated antigens and an enhanced understanding of the immunosuppressive tumor microenvironment have provided opportunities to enable the immune system to recognize cancer cells. Due to its differential upregulation and functional role in PC, the transmembrane mucin MUC4 is an attractive target for immunotherapy. In the current study we characterized the antigen stability, antigenicity and release kinetics of a MUC4ß-nanovaccine to guide further optimization and, in vivo evaluation. Amphiphilic polyanhydride copolymers based on 20 mol % 1,8-bis(p-carboxyphenoxy)-3,6-dioxaoctane and 80 mol % 1,6-bis(p-carboxyphenoxy)hexane were used to synthesize nanoparticles. Structurally stable MUC4ß protein was released from the particles in a sustained manner and characterized by gel electrophoresis and fluorescence spectroscopy. Modest levels of protein degradation were observed upon release. The released protein was also analyzed by MUC4ß-specific monoclonal antibodies using ELISA and showed no significant loss of epitope availability. Further, mice immunized with multiple formulations of combination vaccines containing MUC4ß-loaded nanoparticles generated MUC4ß-specific antibody responses. These results indicate that polyanhydride nanoparticles are viable MUC4ß vaccine carriers, laying the foundation for evaluation of this platform for PC immunotherapy.

Epithelial-mesenchymal transition in undifferentiated carcinoma of the pancreas with and without osteoclast-like giant cells.

Undifferentiated carcinoma (UC) and undifferentiated carcinoma with osteoclast-like giant cells (UCOGC) are peculiar variants of pancreatic ductal adenocarcinoma (PDAC), characterized by hypercellularity and absence of glandular patterns. The inflammatory microenvironment is peculiar in UCOGC, since it is dominated by macrophages and osteoclast-like giant cells. However, from a molecular point of view, both UC and UCOGC are very similar to conventional PDAC, sharing alterations of the most common genetic drivers. Clinically, UC usually show a worse prognosis, whereas UCOGC may show a better prognosis if it is not associated with a PDAC component. To highlight potential biological differences between these entities, we investigated the role of the epithelial to mesenchymal transition (EMT) in UC and UCOGC. Specifically, we analyzed the immunohistochemical expression of three well-known EMT markers, namely Twist1, Snai2, and E-cadherin, in 16 cases of UCOGC and 10 cases of UC. We found that EMT is more frequently activated in UC (10/10 cases) than in UCOGC (8/16 cases; p = 0.05). Furthermore, in UCOGC, EMT was activated with a higher frequency in cases with an associated PDAC component. Snai2 was the most frequently and strongly expressed marker in both tumor types (10/10 UC, 8/16 UCOGC), and its expression was higher in UC than in UCOGC (mean immunohistochemical score: 4.8 in UC vs. 2.1 in UCOGC, p < 0.01). Our results shed new light on the biology of UC and UCOGC: EMT appeared as a more important process in UC, and Snai2 emerged as a central EMT effector in this setting.

Expression of CD117, CK17, CK20, MUC4, villin and mismatch repair deficiency in pancreatic intraductal papillary mucinous neoplasm.

Among pancreatic intraductal papillary neoplasms, gastric, intestinal, and pancreatobiliary intraductal papillary mucinous neoplasm (IPMN), intraductal oncocytic papillary neoplasm (IOPN), and intraductal tubulopapillary neoplasm (ITPN) have been defined, differing regarding association with invasive carcinoma and prognosis. Immunohistochemistry (IHC) can help in the distinction of these neoplasms, but a proportion is unclassifiable using recommended markers. Hence, additional markers useful for the typing of pancreatic intraductal papillary neoplasms are needed. The reported frequencies of the different types of IPMNs in surgical series vary to some extent, and such data based on Danish patients are currently lacking. Besides, the role of mismatch repair (MMR) deficiency in these neoplasms has not been fully elucidated. We aimed to evaluate the frequency of different types of pancreatic intraductal papillary neoplasms in a Danish cohort. Furthermore, we aimed to examine the utility of CD117, CK17, CK20, MUC4, and villin as markers for their distinction, in addition to the recommended markers MUC1, MUC2, MUC5AC, MUC6 and CDX2, and to evaluate the frequency of MMR deficiency. We typed 40 consecutively resected pancreatic intraductal papillary neoplasms according to the WHO criteria from 2019. IHC for CD117, CDX2, CK17, CK20, MLH1, MSH2, MSH6, MUC1 (H23), MUC1 (Ma695), MUC2, MUC4, MUC5AC, MUC6, PMS2, and villin was performed and evaluated using a five-tiered semiquantitative scale. A subset of the tumours was examined with PCR for microsatellite instability (MSI). Most tumours were intestinal (40 %) and gastric (40 %) IPMNs, followed by pancreatobiliary (17 %) IPMNs and IOPN (3 %). All cases were MMR proficient. We found a higher expression of MUC4, CK20 and villin in intestinal compared to gastric IPMNs (p < 0.01, p < 0.001 and p < 0.001). MUC4 was more strongly expressed in intestinal compared to pancreatobiliary IPMNs, while the opposite was found for CK17 (p < 0.05 and p < 0.05). IOPN showed strong CD117 expression (score 4), while all gastric IPMNs were negative and 50 % and 29 % of intestinal and pancreatobiliary IPMNs only showed weak expression (score 1). Our data suggest that CK20, MUC4 and villin may aid in the identification of intestinal IPMNs, while CK17 and CD117 may aid in the identification of pancreatobiliary IPMNs and IOPN, in some cases. However, additional studies evaluating these markers in pancreatic intraductal papillary neoplasms are needed.

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.