The Immune Microenvironment in Pancreatic Cancer

Prosaposin, tumor-secreted protein, promotes pancreatic cancer progression by decreasing tumor-infiltrating lymphocytes

Glycoproteins produced by tumor cells are involved in cancer progression, metastasis, and the immune response, and serve as possible therapeutic targets. Considering the dismal outcomes of pancreatic ductal adenocarcinoma (PDAC) due to its unique tumor microenvironment, which is characterized by low antitumor T-cell infiltration, we hypothesized that tumor-derived glycoproteins may serve as regulating the tumor microenvironment. We used glycoproteomics with tandem mass tag labeling to investigate the culture media of three human PDAC cell lines, and attempted to identify the key secreted proteins from PDAC cells. Among the identified glycoproteins, prosaposin (PSAP) was investigated for its functional contribution to PDAC progression. PSAP is highly expressed in various PDAC cell lines; however, knockdown of intrinsic PSAP expression did not affect the proliferation and migration capacities. Based on the immunohistochemistry of resected human PDAC tissues, high PSAP expression was associated with poor prognosis in patients with PDAC. Notably, tumors with high PSAP expression showed significantly lower CD8+ T-cell infiltration than those with low PSAP expression. Furthermore, PSAP stimulation decreased the proportion of CD8+ T cells in peripheral blood monocytes. Finally, in an orthotopic transplantation model, the number of CD8+ T cells in the PSAP shRNA groups was significantly increased, resulting in a decreased tumor volume compared with that in the control shRNA group. PSAP suppresses CD8+ T-cell infiltration, leading to the promotion of PDAC progression. However, further studies are warranted to determine whether this study contributes to the development of a novel immunomodulating therapy for PDAC.

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.

Turning towards nonimmunoreactive tumors: Evaluation of cancer-associated fibroblasts enables prediction of the immune microenvironment and treatment sensitivity in pancreatic cancer

Increasing evidence has confirmed that cancer-associated fibroblasts (CAFs) recruit and induce regulatory T cells (Tregs) and macrophages but inhibit cytotoxic T lymphocyte infiltration to a certain extent, indicating that CAFs have a significant influence on the immunosuppressive microenvironment. However, the effect of CAFs on the immune microenvironment and immunotherapy response in pancreatic cancer remains unclear. Our research identified remarkable variation in CAF-associated molecules in multiple cancer types at the genetic and transcriptome levels. Two phenotypes were identified for 476 pancreatic cancer samples, and the different phenotypes exhibited significant variation in immune and inflammatory characteristics. Phenotype 1 exhibited higher levels of immune infiltration and lower expression of tumor-associated gene signatures than phenotype 2. We used a multipart approach to assess the prognostic value of CAF-associated molecules and constructed a CAF score model that could accurately predict patient prognosis. The CAF score accurately predicted infiltrating immune cell abundance, chemosensitivity, and the response to immunotherapy. Additionally, we found that the CAF-associated molecule FGFR4 may promote the proliferation and migration and inhibit the apoptosis of pancreatic cancer cells and is correlated with immune infiltration, suggesting its potential role as an oncogene. CAFs may promote the malignant biological behavior of pancreatic cancer through FGFR4. In summary, our research highlights potential relationships of the dysregulation of CAF-associated molecules with genome alterations and carcinogenesis in multiple malignancies. Our CAF-associated phenotypes and scoring system may enhance the understanding of pancreatic cancer chemotherapy sensitivity and immunotherapy response, providing new insights for personalized chemotherapy and immunotherapy.

Conditioned media of pancreatic cancer cells and pancreatic stellate cells induce myeloid-derived suppressor cells differentiation and lymphocytes suppression

As pancreatic cancer cells (PCCs) and pancreatic stellate cells (PSCs) are the two major cell types that comprise the immunosuppressive tumor microenvironment of pancreatic cancer, we aimed to investigate the role of conditioned medium derived from PCCs and PSCs co-culture on the viability of lymphocytes. The conditioned medium (CM) collected from PCCs and/or PSCs was used to treat peripheral blood mononuclear cells (PBMCs) to determine CM ability in reducing lymphocytes population. A proteomic analysis has been done on the CM to investigate the differentially expressed protein (DEP) expressed by two PCC lines established from different stages of tumor. Subsequently, we investigated if the reduction of lymphocytes was directly caused by CM or indirectly via CM-induced MDSCs. This was achieved by isolating lymphocyte subtypes and treating them with CM and CM-induced MDSCs. Both PCCs and PSCs were important in suppressing lymphocytes, and the PCCs derived from a metastatic tumor appeared to have a stronger suppressive effect than the PCCs derived from a primary tumor. According to the proteomic profiles of CM, 416 secreted proteins were detected, and 13 DEPs were identified between PANC10.05 and SW1990. However, CM was found unable to reduce lymphocytes viability through a direct pathway. In contrast, CM that contains proteins secreted by PCC and/or PSC appear immunogenic as they increase the viability of lymphocytes subtypes. Lymphocyte subtype treated with CM-induced MDSCs showed reduced viability in T helper 1 (Th1), T helper 2 (Th2), and T regulatory (Treg) cells, but not in CD8+ T cells, and B cells. As a conclusion, the interplay between PCCs and PSCs is important as their co-culture displays a different trend in lymphocytes suppression, hence, their co-culture should be included in future studies to better mimic the tumor microenvironment.

TP53-Status-Dependent Oncogenic EZH2 Activity in Pancreatic Cancer

Simple Summary

Epigenetic alterations contribute to the aggressiveness and therapy resistance of Pancreatic Ductal Adenocarcinoma (PDAC). However, epigenetic regulators, including Enhancer of Zeste Homolog 2 (EZH2), reveal a strong context-dependent activity. Our study aimed to examine the context-defining molecular prerequisites of oncogenic EZH2 activity in PDAC to assess the therapeutic efficacy of targeting EZH2. Our preclinical study using diverse PDAC models demonstrates that the TP53 status determines oncogenic EZH2 activity. Only in TP53-wildtype (wt) PDAC subtypes was EZH2 blockade associated with a favorable PDAC prognosis mainly through cell-death response. We revealed that EZH2 depletion increases p53wt stability by the de-repression of CDKN2A. Therefore, our study provides preclinical evidence that an intact CDKN2A-p53wt axis is indispensable for a beneficial outcome of EZH2 depletion and highlights the significance of molecular stratification to improve epigenetic targeting in PDAC.

Abstract

Pancreatic Ductal Adenocarcinoma (PDAC) represents a lethal malignancy with a consistently poor outcome. Besides mutations in PDAC driver genes, the aggressive tumor biology of the disease and its remarkable therapy resistance are predominantly installed by potentially reversible epigenetic dysregulation. However, epigenetic regulators act in a context-dependent manner with opposing implication on tumor progression, thus critically determining the therapeutic efficacy of epigenetic targeting. Herein, we aimed at exploring the molecular prerequisites and underlying mechanisms of oncogenic Enhancer of Zeste Homolog 2 (EZH2) activity in PDAC progression. Preclinical studies in EZH2 proficient and deficient transgenic and orthotopic in vivo PDAC models and transcriptome analysis identified the TP53 status as a pivotal context-defining molecular cue determining oncogenic EZH2 activity in PDAC. Importantly, the induction of pro-apoptotic gene signatures and processes as well as a favorable PDAC prognosis upon EZH2 depletion were restricted to p53 wildtype (wt) PDAC subtypes. Mechanistically, we illustrate that EZH2 blockade de-represses CDKN2A transcription for the subsequent posttranslational stabilization of p53wt expression and function. Together, our findings suggest an intact CDKN2A-p53wt axis as a prerequisite for the anti-tumorigenic consequences of EZH2 depletion and emphasize the significance of molecular stratification for the successful implementation of epigenetic targeting in PDAC.

Increased Expression of Mitochondrial UQCRC1 in Pancreatic Cancer Impairs Antitumor Immunity of Natural Killer Cells via Elevating Extracellular ATP

Pancreatic cancer (PC) is one of the most lethal malignancies characterized by a highly immunosuppressive tumor microenvironment (TME). Previously, we have reported that ubiquinol-cytochrome c reductase core protein I (UQCRC1), a key component of mitochondrial complex III, is generally upregulated in PC and produces extracellular ATP (eATP) to promote PC progression. Here, we sought to investigate whether the oncogenic property of UQCRC1 is generated through its effects on natural killer (NK) cells in the TME. We found that UQCRC1 overexpression in PC cells inhibited cytotoxicity of NK cells, as well as the infiltration of NK cells toward PC, whereas knockdown of UQCRC1 enhanced the cytotoxicity and chemotaxis of NK cells. Adoptive NK cell therapy in the subcutaneous mouse model and CIBERSORTx analysis with human PC specimens confirmed UQCRC1 elicited immunosuppressive effects on NK cells. Such UQCRC1-induced impairment of NK cells was mediated by eATP and its metabolite adenosine via P2Y11R and A2AR, respectively. Mechanistically, we found the UQCRC1/eATP axis reduced the expression of chemokine CCL5 in cancer cells and altered the balance of activating receptor DNAM-1 and inhibitory receptor CD96 on NK-92MI cells, resulting in decreased chemotaxis and exhausted phenotype of NK-92MI cells. Taken together, our study provides the evidence to support a novel mechanism by which energy metabolism change in cancer cells remodels the TME and impedes NK cell surveillance. It also suggests that targeting UQCRC1 may be a potential combined strategy for PC immunotherapy.

Identification of Prognosis-Related Molecular Subgroups and Construction of a Prognostic Prediction Model Using Immune-Related Genes in Pancreatic Cancer

Background

Pancreatic cancer patients with similar clinicopathological status exhibit substantially different therapeutic responses, which might be caused by the vast molecular heterogeneity of tumors. In this study, we attempted to identify specific molecular subgroups and construct a prognostic prediction model based on the expression level of immune-related genes in pancreatic cancer. The transcriptome profiling, single nucleotide variation, copy number variation, clinicopathological information, and follow-up data of pancreatic cancer patients were obtained from The Cancer Genome Atlas database. Thereafter, the immune-related genes with prognostic significance were identified for further consensus cluster analysis. The molecular characteristics and clinicopathological information were compared between the identified subgroups, and a weighted correlation network analysis was performed to identify the hub genes associated with the subgroups. Finally, the prognostic prediction model based on immune-related genes was established using the least absolute shrinkage and selection operator (LASSO) analysis.

Results

A total of 67 immune-relevant genes with prognostic significance were selected and used for the consensus cluster analysis. The total samples were divided into two groups, C1 and C2. The subgroup C1 had a significantly worse prognosis than C2, as well as lower levels of immune cell infiltration, which indicate an immunosuppressed state. The mutational rate of the cancer-related genes including KRAS, TP53, and RNF43 was higher in the C1 subgroup. The C1 subgroup was associated with more advanced tumor grade and T stage and with higher mortality. Using LASSO regression, we developed a prognostic prediction model based on the expression levels of 19 immune-related genes, which we validated in three external data sets. In addition, we identified four potential therapeutic and prognostic biomarkers (TNNT1, KCNN4, SH2D3A, and PHLDA2).

Conclusion

We identified two novel molecular subgroups of pancreatic cancer and developed a prognostic prediction model based on the expression levels of immune-related genes, which could be used in a clinical setting and could aid in unraveling the molecular processes leading to the development of pancreatic cancer.

Systemic Therapy of Metastatic Pancreatic Adenocarcinoma: Current Status, Challenges, and Opportunities

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy characterized by nonspecific presenting symptoms, lack of a screening test, rapidly progressive clinical course, and presentation with an advanced-stage disease in the majority of patients. PDAC is essentially a systemic disease irrespective of the initial stage, as most patients with non-metastatic PDAC undergoing curative-intent treatment eventually experience metastatic relapse. Currently, cytotoxic chemotherapy remains the cornerstone of treatment in patients with advanced disease. However, the current standard treatment with multiagent chemotherapy has modest efficacy and results in median overall survival (OS) of less than a year and a 5-year OS of about 10%. The pathobiology of PDAC poses many challenges, including a unique tumor microenvironment interfering with drug delivery, intratumoral heterogeneity, and a strongly immunosuppressive microenvironment that supports cancer growth. Recent research is exploring a wide range of novel therapeutic targets, including genomic alterations, tumor microenvironment, and tumor metabolism. The rapid evolution of tumor genome sequencing technologies paves the way for personalized, targeted therapies. The present review summarizes the current chemotherapeutic treatment paradigm of advanced PDAC and discusses the evolving novel targets that are being investigated in a myriad of clinical trials.

The Trinity: Interplay among Cancer Cells, Fibroblasts, and Immune Cells in Pancreatic Cancer and Implication of CD8+ T Cell-Orientated Therapy

The microenvironment in tumors is complicated and is constituted by different cell types and stromal proteins. Among the cell types, the abundance of cancer cells, fibroblasts, and immune cells is high and these cells work as the “Trinity” in promoting tumorigenesis. Although unidirectional or bidirectional crosstalk between two independent cell types has been well characterized, the multi-directional interplays between cancer cells, fibroblasts, and immune cells in vitro and in vivo are still unclear. We summarize recent studies in addressing the interaction of the “Trinity” members in the tumor microenvironment and propose a functional network for how these members communicate with each other. In addition, we discuss the underlying mechanisms mediating the interplay. Moreover, correlations of the alterations in the distribution and functionality of cancer cells, fibroblasts, and immune cells under different circumstances are reviewed. Finally, we point out the future application of CD8⁺ T cell-oriented therapy in the treatment of pancreatic cancer.

Restored CD8+PD-1+ T Cells Facilitate the Response to Anti-PD-1 for Patients With Pancreatic Ductal Adenocarcinoma

Purpose

We aimed to investigate the restoration of CD8⁺PD-1⁺ T cells through adoptive T-cell therapy (ACT) in relation to the prognosis and the therapeutic response to anti-PD-1 in patients with advanced pancreatic cancer (APC).

Methods

A total of 177 adult patients who underwent tumor resection as initial treatment for pancreatic ductal adenocarcinoma (PDAC) from February 2013 to July 2019 at Zhongnan Hospital of Wuhan University were enrolled in this study. Another cohort of 32 patients with APC was prospectively enrolled from Capital Medical University Cancer Center between June 1, 2013, and May 30, 2019.

Results

Of the 177 patients who received tumor resection, 67 tumor samples showed overexpression of PD-L1 and 110 patients with low expression of PD-L1. We found that overexpressed PD-L1 was a significant prognostic factor related to overall survival (OS). Furthermore, we tested the percentage of peripheral CD8⁺PD-1⁺ T cells in all patients and found that it was significantly correlated with the PD-L1 expression and the prognosis of patients with PDAC. The peripheral blood T lymphocyte subtypes were tracked for 30 months, and CD8⁺PD-1⁺ cells were shown to decrease. After that, we performed ACT for patients with APC in another cancer center. We found that the ratios of posttreatment of ACT/pre-ACT CD8⁺PD-1⁺ T cells were significantly related to the prognosis of patients with APC. Moreover, patients with combined treatment of ACT with anti-PD-1 had significantly favorable OS.

Conclusions

This study showed that the CD8⁺PD-1⁺ T-cell level was related to the expression of PD-L1. Restoring CD8⁺PD-1⁺ T cells in patients with APC by treatment of ACT significantly benefits the prognosis and facilitates the response to anti-PD-1.

Proteomics Approach Highlights Early Changes in Human Fibroblasts-Pancreatic Ductal Adenocarcinoma Cells Crosstalk

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer mortality worldwide. Non-specific symptoms, lack of biomarkers in the early stages, and drug resistance due to the presence of a dense fibrous stroma all contribute to the poor outcome of this disease. The extracellular matrix secreted by activated fibroblasts contributes to the desmoplastic tumor microenvironment formation. Given the importance of fibroblast activation in PDAC pathology, it is critical to recognize the mechanisms involved in the transformation of normal fibroblasts in the early stages of tumorigenesis. To this aim, we first identified the proteins released from the pancreatic cancer cell line MIA-PaCa2 by proteomic analysis of their conditioned medium (CM). Second, normal fibroblasts were treated with MIA-PaCa2 CM for 24 h and 48 h and their proteostatic changes were detected by proteomics. Pathway analysis indicated that treated fibroblasts undergo changes compatible with the activation of migration, vasculogenesis, cellular homeostasis and metabolism of amino acids and reduced apoptosis. These biological activities are possibly regulated by ITGB3 and TGFB1/2 followed by SMAD3, STAT3 and BAG3 activation. In conclusion, this study sheds light on the crosstalk between PDAC cells and associated fibroblasts. Data are available via ProteomeXchange with identifier PXD030974.

Loss of Interleukin-13-Receptor-Alpha-1 Induces Apoptosis and Promotes EMT in Pancreatic Cancer

In search of new therapies for pancreatic cancer, cytokine pathways have attracted increasing interest in recent years. Cytokines play a vital role in the crosstalk between tumour cells and the tumour microenvironment. The related inflammatory cytokines IL-4 and IL-13 can regularly be detected at increased levels in the microenvironment of pancreatic cancer. They share a receptor heterodimer consisting of IL-4Rα and IL-13Rα1. While IL-4Rα induces a more oncogenic phenotype, the role of IL-13Rα1 was yet to be determined. ShRNA-based knockdown of IL-13Rα1 was performed in Capan-1 and MIA PaCa-2. We assessed cell growth and migratory capacities under the influence of IL-13Rα1. Pathway alterations were detected by immunoblot analysis. We now have demonstrated that the loss of IL-13Rα1 induces apoptosis in pancreatic cancer cells. This was associated with an epithelial-to-mesenchymal transition. Loss of IL-13Rα1 also abolished the effects of exogenous IL-4 and IL-13 stimulation. Interestingly, in wild type cells, cytokine stimulation caused a similar increase in migratory capacities as after IL-13Rα1 knockdown. Overall, our results indicate the vital role of IL-13Rα1 in the progression of pancreatic cancer. The differential expression of IL-4Rα and IL-13Rα1 has to be taken into account when considering a cytokine-targeted therapy in pancreatic cancer.

Overexpressing PLOD Family Genes Predict Poor Prognosis in Pancreatic Cancer

Background

Pancreatic cancer is a common malignant tumor. Multiple studies have shown that procollagen lysyl-hydroxylase (PLOD) family genes were closely related to tumor progression and metastasis in a variety of human cancers. This study aimed to explore the prognosis and biological role of PLOD family genes in pancreatic adenocarcinoma (PAAD).

Methods

GEPIA, GEO, HPA, CCLE, Kaplan-Meier plotter, cBioPortal, LinkedOmics, DAVID6.8, STRING, and TIMER were employed to determine the prognostic values and biological function of PLOD family members in PAAD.

Results

The mRNA and protein expression patterns of PLOD family members were noticeably up-regulated in PAAD compared with normal tissues. PLOD family gene expression was also up-regulated in pancreatic cancer cell lines. PLOD1 was correlated with histological and pathological grades of pancreatic cancer. PLOD2 was related to histological grade. The high expression of PLOD1-2 was correlated with the poor overall survival rate and relapse-free survival rate in patients with PAAD. Additionally, PLODs showed high sensitivity and specificity in distinguishing pancreatic cancer from normal tissues. Through the functional enrichment analysis of PLOD-related genes in PAAD, we found that PLODs were enriched in collagen fiber tissue structure, lysine degradation, and collagen biosynthesis. Pathway analysis confirmed that PLODs regulated the proliferation, migration, and metastasis of pancreatic cancer through the RalGEF-Ral signaling pathway. Furthermore, the level of expression of PLOD1-2 was positively correlated with the activity of tumor-infiltrating immune cells, including CD8+T cells, neutrophils, macrophages, and dendritic cells. The level of expression of PLOD3 was inversely correlated with the level of infiltration of CD8+T cells. PLOD1 and PLOD2 were highly expressed in pancreatic cancer tissues with TP53 and KRAS mutations, respectively. However, the level of expression of PLOD3 in SMAD4 wild-type pancreatic cancer was increased.

Conclusion

The findings showed that individual PLOD genes or PLOD family genes could be potential prognostic biomarkers for PAAD.

Role of TFRC as a Novel Prognostic Biomarker and in Immunotherapy for Pancreatic Carcinoma

Objective: To explore the expression of the transferrin receptor (TFRC) gene in pancreatic cancer and to analyze the pathogenesis and immunotherapy of TFRC in patients using bioinformatics methods.

Methods: We used public data from the cancer genome atlas (TCGA) and gene expression omnibus databases to explore the expression level of the TFRC gene in pancreatic cancer patients. At the same time, we analyzed the correlation between the TFRC gene expression and patient survival, and further analyzed the correlation between TFRC and survival time of patients with different clinicopathological characteristics. Co-expressed genes and pathway enrichment analyses were used to analyze the mechanism of the TFRC in the occurrence and development of pancreatic cancer. Ultimately, we used the R software to examine the relationship between TFRC and immune phenotypes and immune cell infiltration using the TCGA database.

Results: The results of the study showed that TFRC is highly expressed in pancreatic cancer tissue. The upregulated expression of TFRC was negatively correlated with the survival in patients with pancreatic cancer. The bioinformatics analysis showed that TFRC plays a role in the occurrence and development of pancreatic cancer mainly through signaling pathways (including cell adhesion molecule binding, condensed chromosomes, chromosome segregation, and cell cycle checkpoints). Finally, TFRC is associated with immune phenotypes and immune cell infiltration, which may influence immunotherapy.

Conclusion: TFRC is significantly increased in pancreatic cancer and is associated with a poor prognosis. Moreover, research on TFRC may generate new ideas for the immunotherapy of pancreatic cancer.

GaWRDenMap: a quantitative framework to study the local variation in cell-cell interactions in pancreatic disease subtypes

Spatial pattern modelling concepts are being increasingly used in capturing disease heterogeneity. Quantification of heterogeneity in the tumor microenvironment is extremely important in pancreatic ductal adenocarcinoma (PDAC), which has been shown to co-occur with other pancreatic diseases and neoplasms with certain attributes that make visual discrimination difficult. In this paper, we propose the GaWRDenMap framework, that utilizes the concepts of geographically weighted regression (GWR) and a density function-based classification model, and apply it to a cohort of multiplex immunofluorescence images from patients belonging to six different pancreatic diseases. We used an internal cohort of 228 patients comprised of 34 Chronic Pancreatitis (CP), 71 PDAC, 70 intraductal papillary mucinous neoplasm (IPMN), 16 mucinous cystic neoplasm (MCN), 29 pancreatic intraductal neoplasia (PanIN) and 8 IPMN-associated PDAC patients. We utilized GWR to model the relationship between epithelial cells and immune cells on a spatial grid. The GWR model estimates were used to generate density signatures which were used in subsequent pairwise classification models to distinguish between any two pairs of disease groups. Image-level, as well as subject-level analysis, were performed. When applied to this dataset, our classification model showed significant discrimination ability in multiple pairwise comparisons, in comparison to commonly used abundance-based metrics, like the Morisita-Horn index. The model was able to best discriminate between CP and PDAC at both the subject- and image-levels. It was also able to reasonably discriminate between PDAC and IPMN. These results point to a potential difference in the spatial arrangement of epithelial and immune cells between CP, PDAC and IPMN, that could be of high diagnostic significance. Further validation on a more comprehensive dataset would be warranted.

Rintatolimod (Ampligen®) Enhances Numbers of Peripheral B Cells and Is Associated with Longer Survival in Patients with Locally Advanced and Metastasized Pancreatic Cancer Pre-Treated with FOLFIRINOX: A Single-Center Named Patient Program

Background: Treatment with the TLR-3 agonist rintatolimod may improve pancreatic cancer patients’ survival via immunomodulation, but the effect is unproven. Methods: In this single-center named patient program, patients with locally advanced pancreatic cancer (LAPC) or metastatic disease were treated with rintatolimod (six weeks total, twice per week, with a maximum of 400 mg per infusion). The primary endpoints were the systemic immune-inflammation index (SIII), the neutrophil to lymphocyte ratio (NLR), and the absolute counts of 18 different populations of circulating immune cells as measured by flow cytometry. Secondary endpoints were progression-free survival (PFS) and overall survival (OS). Subgroup analyses were performed in long-term survivors (>1-year overall survival after starting rintatolimod) and compared to short-term survivors (≤1 year). Results: Between January 2017 and February 2019, twenty-seven patients with stable LAPC or metastatic disease were pre-treated with FOLFIRINOX and treated with rintatolimod. Rintatolimod treatment was well-tolerated. The SIII and NLR values were significantly lower in the 11 long-term survivors, versus 16 short-term survivors. The numbers of B-cells were significantly increased in long-term survivors. Numbers of T cells and myeloid cells were not significantly increased after treatment with rintatolimod. Median PFS was 13 months with rintatolimod, versus 8.6 months in a subset of matched controls (n = 27, hazard ratio = 0.52, 95% CI = 0.28−0.90, p = 0.007). The median OS was 19 months with rintatolimod, versus 12.5 months in the matched control (hazard ratio = 0.51, 95% CI = 0.28−0.90, p = 0.016). Conclusions: Treatment with rintatolimod showed a favorable effect on the numbers of peripheral B cells in patients with pancreatic cancer and improved survival in pancreatic cancer, but additional evidence is required.

Modulation of Type I Interferon Responses to Influence Tumor-Immune Cross Talk in PDAC

Immunotherapy has revolutionized the treatment of many cancer types. However, pancreatic ductal adenocarcinomas (PDACs) exhibit poor responses to immune checkpoint inhibitors with immunotherapy-based trials not generating convincing clinical activity. PDAC tumors often have low infiltration of tumor CD8+ T cells and a highly immunosuppressive microenvironment. These features classify PDAC as immunologically "cold." However, the presence of tumor T cells is a favorable prognostic feature in PDAC. Intrinsic tumor cell properties govern interactions with the immune system. Alterations in tumor DNA such as genomic instability, high tumor mutation burden, and/or defects in DNA damage repair are associated with responses to both immunotherapy and chemotherapy. Cytotoxic or metabolic stress produced by radiation and/or chemotherapy can act as potent immune triggers and prime immune responses. Damage- or stress-mediated activation of nucleic acid-sensing pathways triggers type I interferon (IFN-I) responses that activate innate immune cells and natural killer cells, promote maturation of dendritic cells, and stimulate adaptive immunity. While PDAC exhibits intrinsic features that have the potential to engage immune cells, particularly following chemotherapy, these immune-sensing mechanisms are ineffective. Understanding where defects in innate immune triggers render the PDAC tumor-immune interface less effective, or how T-cell function is suppressed will help develop more effective treatments and harness the immune system for durable outcomes. This review will focus on the pivotal role played by IFN-I in promoting tumor cell-immune cell cross talk in PDAC. We will discuss how PDAC tumor cells bypass IFN-I signaling pathways and explore how these pathways can be co-opted or re-engaged to enhance the therapeutic outcome.

ADAM8-Dependent Extracellular Signaling in the Tumor Microenvironment Involves Regulated Release of Lipocalin 2 and MMP-9

The metalloprotease-disintegrin ADAM8 is critically involved in the progression of pancreatic cancer. Under malignant conditions, ADAM8 is highly expressed and could play an important role in cell–cell communication as expression has been observed in tumor and immune cells of the tumor microenvironment (TME) such as macrophages. To analyze the potential role of ADAM8 in the TME, ADAM8 knockout PDAC tumor cells were generated, and their release of extracellular vesicles (EVs) was analyzed. In EVs, ADAM8 is present as an active protease and associated with lipocalin 2 (LCN2) and matrix metalloprotease 9 (MMP-9) in an ADAM8-dependent manner, as ADAM8 KO cells show a lower abundance of LCN2 and MMP-9. Sorting of ADAM8 occurs independent of TSG101, even though ADAM8 contains the recognition motif PTAP for the ESCRTI protein TSG101 within the cytoplasmic domain (CD). When tumor cells were co-cultured with macrophages (THP-1 cells), expression of LCN2 and MMP-9 in ADAM8 KO cells was induced, suggesting that macrophage signaling can overcome ADAM8-dependent intracellular signaling in PDAC cells. In co-culture with macrophages, regulation of MMP-9 is independent of the M1/M2 polarization state, whereas LCN2 expression is preferentially affected by M1-like macrophages. From these data, we conclude that ADAM8 has a systemic effect in the tumor microenvironment, and its expression in distinct cell types has to be considered for ADAM8 targeting in tumors.

Prkci Regulates Autophagy and Pancreatic Tumorigenesis in Mice

Protein kinase C iota (PKCι) functions as a bonafide human oncogene in lung and ovarian cancer and is required for KrasG12D-mediated lung cancer initiation and progression. PKCι expression is required for pancreatic cancer cell growth and maintenance of the transformed phenotype; however, nothing is known about the role of PKCι in pancreas development or pancreatic tumorigenesis. In this study, we investigated the effect of pancreas-specific ablation of PKCι expression on pancreatic cellular homeostasis, susceptibility to pancreatitis, and KrasG12D-mediated pancreatic cancer development. Knockout of pancreatic Prkci significantly increased pancreatic immune cell infiltration, acinar cell DNA damage, and apoptosis, but reduced sensitivity to caerulein-induced pancreatitis. Prkci-ablated pancreatic acinar cells exhibited P62 aggregation and a loss of autophagic vesicles. Loss of pancreatic Prkci promoted KrasG12D-mediated pancreatic intraepithelial neoplasia formation but blocked progression to adenocarcinoma, consistent with disruption of autophagy. Our results reveal a novel promotive role for PKCι in pancreatic epithelial cell autophagy and pancreatic cancer progression.

Epigenetic Therapeutic Strategies to Target Molecular and Cellular Heterogeneity in Pancreatic Cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) remains a major challenge in cancer medicine and is characterized by a 5-year survival rate of <10%. Compelling evidence suggests that the devastating disease outcome of PDAC patients is linked to a high degree of intra- and interindividual tumor heterogeneity, which is predominantly installed at the level of gene transcription. The cellular and molecular complexities of the disease explain the poor efficacy of "one-size-fits-all" therapeutic approaches in PDAC treatment and strongly argue for pursuing tailored therapeutic strategies to tackle PDAC. In a highly dynamic manner, a network of transcription factors and epigenetic regulatory proteins temporally and spatially control the diverse transcriptomic states determining PDAC heterogeneity. Given the reversibility of epigenetic processes, pharmacological intervention with key epigenetic drivers of PDAC heterogeneity appeals as a promising concept to shift the transcriptomic phenotype of PDAC toward a less aggressive and more chemosensible state.

SUMMARY

In this review, we discuss the chances and pitfalls of epigenetic treatment strategies in overcoming and shifting molecular and cellular PDAC heterogeneities in order to combat PDAC. To this end, we utilized the keywords "pancreatic cancer," "heterogeneity," and "epigenetics" to search for relevant articles on the database PubMed and selected interventional studies enrolling PDAC patients as displayed in clinicaltrails.gov to generate a synopsis of clinical trials involving epigenetic targeting.

KEY MESSAGES

Targeting epigenetic regulators in PDAC represents a promising concept to reprogram molecular and cellular tumor heterogeneities in the pancreas and hence to modulate the PDAC phenotype in favor of a less aggressive and more therapy susceptible disease course. However, we just start to understand the complex interactions of epigenetic regulators in controlling PDAC plasticity, and a clinical breakthrough utilizing epigenetic targeting in PDAC patients has not been achieved yet. Nevertheless, increasing translational efforts which consider the pleiotropic effects of targeting epigenetic regulation in different cellular compartments of the tumor and that focus on the utility and sequence of combinatory treatment approaches might pave the way toward novel epigenetic treatment strategies in PDAC therapy.

The Efficacy and Safety of PD-1 Inhibitors Combined with Nab-Paclitaxel Plus Gemcitabine versus Nab-Paclitaxel Plus Gemcitabine in the First-Line Treatment of Advanced Pancreatic Cancer: A Retrospective Monocentric Study

Purpose

The purpose of this study was to evaluate the efficacy and safety of PD-1 inhibitor combined with nab-paclitaxel plus gemcitabine (AG) chemotherapy versus AG chemotherapy in the first-line treatment of advanced pancreatic cancer.

Patients and Methods

This study included the application of AG treatment and PD-1 combined with AG treatment with advanced pancreatic ductal adenocarcinoma at the Affiliated Hospital of Qingdao University from September 2018 to July 2020. Clinical information and next-generation sequencing (NGS) reports of patients were collected to compare the effectiveness and adverse events of the two treatments and analyze the risk factors affecting the prognosis of patients.

Results

There was no difference in PFS between the AG group and the PD-1+AG group (4.9 months vs 5.0 months, P = 0.154), but the difference in OS was statistically significant (9.3 months vs 12.1 months, P < 0.001). Compared with the AG group, the PD-1+AG group reduced the risk of death about 20.0% (HR = 0.203, 95% CI, 0.090−0.459, P < 0.001). In terms of safety, the incidence of hypothyroidism and reactive skin capillary hyperplasia in PD-1 + AG group was higher than that in AG group (P < 0.050) in grade 1–2; grade 3–4 adverse reactions were mainly hematologic AEs and abnormal liver function. The incidence of grade 3–4 adverse reactions in the two groups was 38.7% (95% CI, 20.5–56.9%) and 35.3% (95% CI, 10.0–60.6%), respectively. In addition, PD-1+ AG regimen improved the OS of patients with KRAS and TP53 co-mutations (8.0months vs 10.2 months, P = 0.004).

Conclusion

PD-1 inhibitors combined with AG chemotherapy have shown good efficacy and safety in the first-line treatment of patients with advanced pancreatic ductal adenocarcinoma. This regimen similarly improved OS in patients with KRAS and TP53 co-mutations.

Midazolam exhibits antitumour and anti-inflammatory effects in a mouse model of pancreatic ductal adenocarcinoma

BACKGROUND

Anaesthesia and perioperative management contribute to long-term outcomes of patients with cancer, including pancreatic ductal adenocarcinoma. We assessed the antitumour, anti-inflammatory, and analgesic effects of midazolam on LSL-Kras^G12D/+;Trp53^flox/flox;Pdx-1^cre/+ transgenic mice with pancreatic ductal adenocarcinoma.

METHODS

Six-week-old transgenic mice were administered midazolam 30 mg kg^-1 day^-1 p.o. (n=13); midazolam 30 mg kg^-1 day^-1 with 1-(2-chlorophenyl)-N-methyl-N(1-methylpropyl)-3-isoquinoline carboxamide (PK11195) 3 mg kg^-1 day^-1 i.p., a peripheral benzodiazepine receptor antagonist (n=10); or vehicle (water; n=14) until the humane endpoint. Cancer-associated pain was evaluated using hunching score and mouse grimace scale. Tumour stage and immuno-inflammatory status were determined histopathologically. Anti-proliferative and apoptotic potentials of midazolam were investigated using mouse pancreatic ductal adenocarcinoma cell lines.

RESULTS

Midazolam significantly inhibited tumour size and proliferative index of Ki-67 and cyclins in pancreatic ductal adenocarcinoma, which was blocked by administration of PK11195. Local myeloperoxidase⁺ tumour-associated neutrophils, arginase-1⁺ M2-like tumour-associated macrophages, and CD11b⁺Ly-6G⁺ polymorphonuclear myeloid-derived suppressor cells were reduced by midazolam, which was antagonised by administration of PK11195. Hunching and mouse grimace scale were improved by midazolam, whereas the scores increased with midazolam+PK11195 treatment. Plasma pro-inflammatory cytokines, such as interleukin-6 and CC chemokine ligand (CCL)2, CCL3, and CCL5, were reduced by midazolam, whereas these cytokines increased with PK11195. Midazolam inhibited pancreatic ductal adenocarcinoma proliferation through downregulation of cyclins and cyclin-dependent kinases and induced apoptosis in vitro.

CONCLUSIONS

These results suggest that midazolam inhibits pancreatic ductal adenocarcinoma proliferation and local infiltration of tumour-associated neutrophils, tumour-associated macrophages, and polymorphonuclear myeloid-derived suppressor cells, thereby inhibiting pancreatic ductal adenocarcinoma progression.

Comprehensive analysis of expression profile and prognostic significance of interferon regulatory factors in pancreatic cancer

BACKGROUND

Pancreatic cancer (PC) is a highly lethal disease and an increasing cause of cancer-associated mortality worldwide. Interferon regulatory factors (IRFs) play vital roles in immune response and tumor cellular biological processes. However, the specific functions of IRFs in PC and tumor immune response are far from systematically clarified. This study aimed to explorer the expression profile, prognostic significance, and biological function of IRFs in PC.

RESULTS

We observed that the levels of IRF2, 6, 7, 8, and 9 were elevated in tumor compared to normal tissues in PC. IRF7 expression was significantly associated with patients' pathology stage in PC. PC patients with high IRF2, low IRF3, and high IRF6 levels had significantly poorer overall survival. High mRNA expression, amplification and, deep deletion were the three most common types of genetic alterations of IRFs in PC. Low expression of IRF2, 4, 5, and 8 was resistant to most of the drugs or small molecules from Genomics of Drug Sensitivity in Cancer. Moreover, IRFs were positively correlated with the abundance of tumor infiltrating immune cells in PC, including B cells, CD8+ T cells, CD4+ T cells, macrophages, Neutrophil, and Dendritic cells. Functional analysis indicated that IRFs were involved in T cell receptor signaling pathway, immune response, and Toll-like receptor signaling pathway.

CONCLUSIONS

Our results indicated that certain IRFs could serve as potential therapeutic targets and prognostic biomarkers for PC patients. Further basic and clinical studies are needed to validate our findings and generalize the clinical application of IRFs in PC.

Small extracellular vesicles: from mediating cancer cell metastasis to therapeutic value in pancreatic cancer

Pancreatic cancer is a highly malignant tumor and, is extremely difficult to diagnose and treat. Metastasis is one of the critical steps in the development of cancer and uses cell to cell communication to mediate changes in the microenvironment. Small extracellular vesicles (sEVs)-carry proteins, nucleic acids and other bioactive substances, and are important medium for communication between cells. There are two primary steps in sVEs-mediated metastasis: communication between pancreatic cancer cells and their surrounding microenvironment; and the communication between primary tumor cells and distant organ cells in distant organs that promotes angiogenesis, reshaping extracellular matrix, forming immunosuppressive environment and other ways to form appropriate pre-metastasis niche. Here, we explore the mechanism of localization and metastasis of pancreatic cancer and use sEVs as early biomarkers for the detection and treatment of pancreatic cancer. Video Abstract.

Machine learning analyses of highly-multiplexed immunofluorescence identifies distinct tumor and stromal cell populations in primary pancreatic tumors

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a formidable challenge for patients and clinicians.

OBJECTIVE

To analyze the distribution of 31 different markers in tumor and stromal portions of the tumor microenvironment (TME) and identify immune cell populations to better understand how neoplastic, non-malignant structural, and immune cells, diversify the TME and influence PDAC progression.

METHODS

Whole slide imaging (WSI) and cyclic multiplexed-immunofluorescence (MxIF) was used to collect 31 different markers over the course of nine distinctive imaging series of human PDAC samples. Image registration and machine learning algorithms were developed to largely automate an imaging analysis pipeline identifying distinct cell types in the TME.

RESULTS

A random forest algorithm accurately predicted tumor and stromal-rich areas with 87% accuracy using 31 markers and 77% accuracy using only five markers. Top tumor-predictive markers guided downstream analyses to identify immune populations effectively invading into the tumor, including dendritic cells, CD4+ T cells, and multiple immunoregulatory subtypes.

CONCLUSIONS

Immunoprofiling of PDAC to identify differential distribution of immune cells in the TME is critical for understanding disease progression, response and/or resistance to treatment, and the development of new treatment strategies.

Metabolic syndrome related gene signature predicts the prognosis of patients with pancreatic ductal carcinoma. A novel link between metabolic dysregulation and pancreatic ductal carcinoma

Background

Pancreatic cancer is one of the most common malignancies worldwide. In recent years, specific metabolic activities, which involves the development of tumor, caused wide public concern. In this study, we wish to explore the correlation between metabolism and progression of tumor.

Methods

A retrospective analysis including 95 patients with pancreatic ductal adenocarcinoma (PDAC) and PDAC patients from The Cancer Genome Atlas (TCGA), the International Cancer Genome Consortium (ICGC), and The Gene Expression Omnibus (GEO) database were involved in our study. Multivariate Cox regression analysis was used to construct the prognosis model. The potential connection between metabolism and immunity of PDAC was investigated through a weighted gene co-expression network analysis (WGCNA). 22 types of Tumor-infiltrating immune cells (TIICs) between high-risk and low-risk groups were estimated through CIBERSORT. Moreover, the potential immune-related signaling pathways between high-risk and low-risk groups were explored through the gene set enrichment analysis (GSEA). The role of key gene GMPS in developing pancreatic tumor was further investigated through CCK-8, colony-information, and Transwell.

Results

The prognostic value of the MetS factors was analyzed using the Cox regression model, and a clinical MetS-based nomogram was established. Then, we established a metabolism-related signature to predict the prognosis of PDAC patients based on the TCGA databases and was validated in the ICGC database and the GEO database to find the distinct molecular mechanism of MetS genes in PDAC. The result of WGCNA showed that the blue module was associated with risk score, and genes in the blue module were found to be enriched in the immune-related signaling pathway. Furthermore, the result of CIBERSORT demonstrated that proportions of T cells CD8, T cells Regulatory, Tregs NK cells Activated, Dendritic cells Activated, and Mast cells Resting were different between high-risk and low-risk groups. These differences are potential causes of different prognoses of PDAC patients. GSEA and the protein–protein interaction network (PPI) further revealed that our metabolism-related signature was significantly enriched in immune‐related biological processes. Moreover, knockdown of GMPS in PDAC cells suppressed proliferation, migration, and invasion of tumor cells, whereas overexpression of GMPS performed oppositely.

Conclusion

The results shine light on fundamental mechanisms of metabolic genes on PDAC and establish a reliable and referable signature to evaluate the prognosis of PDAC. GMPS was identified as a potential candidate oncogene with in PDAC, which can be a novel biomarker and therapeutic target for PDAC treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02378-w.

PDAC as an Immune Evasive Disease: Can 3D Model Systems Aid to Tackle This Clinical Problem?

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with a high mortality rate. The presence of a dense desmoplastic stroma rich in fibroblasts, extracellular matrix, and immune cells plays a critical role in disease progression, therapy response and is a distinguishing feature of PDAC. PDAC is currently treated with a combination of surgery, chemotherapy and radiation therapy in selected cases which results in long-term survival only in a small percentage of patients. Cancer therapies that incorporate immunotherapy-based techniques have become increasingly common in recent years. While such a strategy has been shown to be effective for immunogenic, “hot” tumors like melanoma and lung cancer, thus far PDAC patients display poor responses to this therapeutic approach. Various factors, such as low tumor mutational burden, increased infiltration of immunosuppressive cells, like MDSCs and Treg cells promote tolerance and immune deviation, further aggravating adaptive immunity in PDAC. In this review we will elaborate on the ability of PDAC tumors to evade immune detection. We will also discuss various 3D model system that can be used as a platform in preclinical research to investigate rational combinations of immunotherapy with chemotherapy or targeted therapy, to prime the immune microenvironment to enhance antitumor activity.

Tumor Microenvironment in Pancreatic Intraepithelial Neoplasia

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive neoplasm with a poor survival rate. This is mainly due to late detection, which substantially limits therapy options. A better understanding of the early phases of pancreatic carcinogenesis is fundamental for improving patient prognosis in the future. In this article, we focused on the tumor microenvironment (TME), which provides the biological niche for the development of PDAC from its most common precursor lesions, PanIN (pancreatic intraepithelial neoplasias).

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive tumors with a poor prognosis. A characteristic of PDAC is the formation of an immunosuppressive tumor microenvironment (TME) that facilitates bypassing of the immune surveillance. The TME consists of a desmoplastic stroma, largely composed of cancer-associated fibroblasts (CAFs), immunosuppressive immune cells, immunoregulatory soluble factors, neural network cells, and endothelial cells with complex interactions. PDAC develops from various precursor lesions such as pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasms (IPMN), mucinous cystic neoplasms (MCN), and possibly, atypical flat lesions (AFL). In this review, we focus on the composition of the TME in PanINs to reveal detailed insights into the complex restructuring of the TME at early time points in PDAC progression and to explore ways of modifying the TME to slow or even halt tumor progression.

Nanomedicine in Pancreatic Cancer: Current Status and Future Opportunities for Overcoming Therapy Resistance

Simple Summary

Despite access to a vast arsenal of anticancer agents, many fail to realise their full therapeutic potential in clinical practice. One key determinant of this is the evolution of multifaceted resistance mechanisms within the tumour that may either pre-exist or develop during the course of therapy. This is particularly evident in pancreatic cancer, where limited responses to treatment underlie dismal survival rates, highlighting the urgent need for new therapeutic approaches. Here, we discuss the major features of pancreatic tumours that contribute to therapy resistance, and how they may be alleviated through exploitation of the mounting and exciting promise of nanomedicines; a unique collection of nanoscale platforms with tunable and multifunctional capabilities that have already elicited a widespread impact on cancer management.

Abstract

The development of drug resistance remains one of the greatest clinical oncology challenges that can radically dampen the prospect of achieving complete and durable tumour control. Efforts to mitigate drug resistance are therefore of utmost importance, and nanotechnology is rapidly emerging for its potential to overcome such issues. Studies have showcased the ability of nanomedicines to bypass drug efflux pumps, counteract immune suppression, serve as radioenhancers, correct metabolic disturbances and elicit numerous other effects that collectively alleviate various mechanisms of tumour resistance. Much of this progress can be attributed to the remarkable benefits that nanoparticles offer as drug delivery vehicles, such as improvements in pharmacokinetics, protection against degradation and spatiotemporally controlled release kinetics. These attributes provide scope for precision targeting of drugs to tumours that can enhance sensitivity to treatment and have formed the basis for the successful clinical translation of multiple nanoformulations to date. In this review, we focus on the longstanding reputation of pancreatic cancer as one of the most difficult-to-treat malignancies where resistance plays a dominant role in therapy failure. We outline the mechanisms that contribute to the treatment-refractory nature of these tumours, and how they may be effectively addressed by harnessing the unique capabilities of nanomedicines. Moreover, we include a brief perspective on the likely future direction of nanotechnology in pancreatic cancer, discussing how efforts to develop multidrug formulations will guide the field further towards a therapeutic solution for these highly intractable tumours.

Are Circulating Immune Cells a Determinant of Pancreatic Cancer Risk? A Prospective Study Using Epigenetic Cell Count Measures

BACKGROUND

Evidence is accumulating that immune cells play a prominent role in pancreatic cancer etiology but prospective investigations are missing.

METHODS

We conducted a nested case-control study within the European Prospective Investigation into Cancer and Nutrition (EPIC) study with 502 pairs of incident pancreatic cancer cases and matched controls. Relative counts of circulating immune cells (neutrophils and lymphocyte sublineages: total CD3+, CD8+, CD4+, and FOXP3+ regulatory T cells (Tregs) relative to nucleated cells, (white blood cells) were measured by qRT-PCR. ORs with 95% confidence intervals were estimated using logistic regressions, modeling relative counts of immune cells on a continuous scale.

RESULTS

Neither relative counts of immune cell types taken individually, nor mutually adjusted for each other were associated with pancreatic cancer risks. However, in subgroup analyses by strata of lag-time, higher relative counts of Tregs and lower relative counts of CD8+ were significantly associated with an increased pancreatic cancer risks in participants diagnosed within the first 5 years of follow-up.

CONCLUSIONS

These results might reflect reverse causation, due to higher relative counts of Tregs and lower counts of CD8+ cells among individuals with more advanced stages of latent pancreatic cancer, who are closer to the point of developing clinical manifest disease.

IMPACT

We have shown, for the first time, that increased relative counts of regulatory T cells and lower relative counts of CD8+, cytotoxic T cells may be associated with pancreatic cancer risk or relatively late-stage tumor development.See related commentary by Michaud and Kelsey, p. 2176.

Understanding the immune response and the current landscape of immunotherapy in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive tumor with high lethality. Even with surgery, radiotherapy, chemotherapy, and other locoregional or systemic therapies, the survival rates for PDAC are low and have not significantly changed in the past decades. The special characteristics of the PDAC's microenvironment and its complex immune escape mechanism need to be considered when designing novel therapeutic approaches in this disease. PDAC is characterized by chronic inflammation with a high rate of tumor-associated macrophages and myeloid-derived suppressor cells and a low rate of natural killer and effector T cells. The pancreatic microenvironment is a fibrotic, microvascularized stroma that isolates the tumor from systemic vascularization. Immunotherapy, a novel approach that has demonstrated effectiveness in certain solid tumors, has failed to show any practice-changing results in pancreatic cancer, with the exception of PDACs with mismatch repair deficiency and high tumor mutational burden, which show prolonged survival rates with immunotherapy. Currently, numerous clinical trials are attempting to assess the efficacy of immunotherapeutic strategies in PDAC, including immune checkpoint inhibitors, cancer vaccines, and adoptive cell transfer, alone or in combination with other immunotherapeutic agents, chemoradiotherapy, and other targeted therapies. A deep understanding of the immune response will help in the development of new therapeutic strategies leading to improved clinical outcomes for patients with PDAC.

Evolution of Systemic Therapy in Metastatic Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma is characterized by early systemic dissemination, a complex tumor microenvironment, as well as significant intratumoral and intertumoral heterogeneity. Treatment options and survival in pancreatic ductal adenocarcinoma have improved steadily over the last 3 decades. Although cytotoxic chemotherapy is currently the mainstay of treatment for pancreatic ductal adenocarcinoma, evolving therapeutic strategies are aimed at targeting the tumor microenvironment, metabolism, and the tumor-host immune balance.

Group Young Researchers in Inflammatory Carcinogenesis, Wandmacher AM, Mehdorn AS, Sebens S. The Heterogeneity of the Tumor Microenvironment as Essential Determinant of Development, Progression and Therapy Response of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is commonly diagnosed at advanced stages and most anti-cancer therapies have failed to substantially improve prognosis of PDAC patients. As a result, PDAC is still one of the deadliest tumors. Tumor heterogeneity, manifesting at multiple levels, provides a conclusive explanation for divergent survival times and therapy responses of PDAC patients. Besides tumor cell heterogeneity, PDAC is characterized by a pronounced inflammatory stroma comprising various non-neoplastic cells such as myofibroblasts, endothelial cells and different leukocyte populations which enrich in the tumor microenvironment (TME) during pancreatic tumorigenesis. Thus, the stromal compartment also displays a high temporal and spatial heterogeneity accounting for diverse effects on the development, progression and therapy responses of PDAC. Adding to this heterogeneity and the impact of the TME, the microbiome of PDAC patients is considerably altered. Understanding this multi-level heterogeneity and considering it for the development of novel therapeutic concepts might finally improve the dismal situation of PDAC patients. Here, we outline the current knowledge on PDAC cell heterogeneity focusing on different stromal cell populations and outline their impact on PDAC progression and therapy resistance. Based on this information, we propose some novel concepts for treatment of PDAC patients.

Pancreatic Cancer Small Extracellular Vesicles (Exosomes): A Tale of Short- and Long-Distance Communication

Simple Summary

Even today, pancreatic cancer still has a dismal prognosis. It is characterized by a lack of early symptoms and thus late diagnosis as well as early metastasis. The majority of patients suffer from pancreatic ductal adenocarcinoma (PDAC). PDACs communicate extensively with cellular components of their microenvironment, but also with distant metastatic niches to facilitate tumor progression and dissemination. This crosstalk is substantially enabled by small extracellular vesicles (sEVs, exosomes) with a size of 30–150 nm that are released from the tumor cells. sEVs carry bioactive cargos that reprogram target cells to promote tumor growth, migration, metastasis, immune evasion, or chemotherapy resistance. Interestingly, sEVs also carry novel diagnostic, prognostic and potentially also predictive biomarkers. Moreover, engineered sEVs may be utilized as therapeutic agents, improving treatment options. The role of sEVs for PDAC development, progression, diagnosis, prognosis, and treatment is the focus of this review.

Abstract

Even with all recent advances in cancer therapy, pancreatic cancer still has a dismal 5-year survival rate of less than 7%. The most prevalent tumor subtype is pancreatic ductal adenocarcinoma (PDAC). PDACs display an extensive crosstalk with their tumor microenvironment (TME), e.g., pancreatic stellate cells, but also immune cells to regulate tumor growth, immune evasion, and metastasis. In addition to crosstalk in the local TME, PDACs were shown to induce the formation of pre-metastatic niches in different organs. Recent advances have attributed many of these interactions to intercellular communication by small extracellular vesicles (sEVs, exosomes). These nanovesicles are derived of endo-lysosomal structures (multivesicular bodies) with a size range of 30–150 nm. sEVs carry various bioactive cargos, such as proteins, lipids, DNA, mRNA, or miRNAs and act in an autocrine or paracrine fashion to educate recipient cells. In addition to tumor formation, progression, and metastasis, sEVs were described as potent biomarker platforms for diagnosis and prognosis of PDAC. Advances in sEV engineering have further indicated that sEVs might once be used as effective drug carriers. Thus, extensive sEV-based communication and applications as platform for biomarker analysis or vehicles for treatment suggest a major impact of sEVs in future PDAC research.

UEG position paper on pancreatic cancer. Bringing pancreatic cancer to the 21st century: Prevent, detect, and treat the disease earlier and better

BACKGROUND

Pancreatic ductal adenocarcinoma is the deadliest cancer worldwide with a 98% loss-of-life expectancy and a 30% increase in the disability-adjusted life years during the last decade in Europe. The disease cannot be effectively prevented nor being early detected. When diagnosed, 80% of patients have tumors that are in incurable stages, while for those who undergo surgery, 80% of patients will present with local or distant metastasis. Importantly, chemotherapies are far from being effective.

OBJECTIVE

Pancreatic cancer represents a great challenge and, at the same time, a huge opportunity for advancing our understanding on the basis of the disease, the molecular profiles, that would lead to develop tools for early detection and effective treatments, thus, boosting patient survival.

RESULTS

Research on pancreatic cancer has being receiving little or minimal funds from European funding bodies. UEG is calling for public-private partnerships that would effectively fund research on pancreatic cancer.

CONCLUSION

This would increase our understanding of this disease and better treatment, through pan-European efforts that take advantage of the strong academic European research landscape on pancreatic cancer, and the contribution by the industry of all sizes.

Small Extracellular Vesicles and Metastasis-Blame the Messenger

Simple Summary

Due to their systemic nature, metastatic lesions are a major problem for curative cancer treatment. According to a common model for metastasis, tumor cells disseminate by local invasion, survival in the blood stream and extravasation into suitable tissue environments. At secondary sites, metastatic cells adapt, proliferate and foster vascularization to satisfy nutrient and oxygen demand. In recent years, tumors were shown to extensively communicate with cells in the local microenvironment and future metastatic sites by secreting small extracellular vesicles (sEVs, exosomes). sEVs deliver bioactive cargos, e.g., proteins, and in particular, several nucleic acid classes to reprogram target cells, which in turn facilitate tumor growth, cell motility, angiogenesis, immune evasion and establishment of pre-metastatic niches. sEV-cargos also act as biomarkers for diagnosis and prognosis. This review discusses how tumor cells utilize sEVs with nucleic acid cargos to progress through metastasis, and how sEVs may be employed for prognosis and treatment.

Abstract

Cancer is a complex disease, driven by genetic defects and environmental cues. Systemic dissemination of cancer cells by metastasis is generally associated with poor prognosis and is responsible for more than 90% of cancer deaths. Metastasis is thought to follow a sequence of events, starting with loss of epithelial features, detachment of tumor cells, basement membrane breakdown, migration, intravasation and survival in the circulation. At suitable distant niches, tumor cells reattach, extravasate and establish themselves by proliferating and attracting vascularization to fuel metastatic growth. These processes are facilitated by extensive cross-communication of tumor cells with cells in the primary tumor microenvironment (TME) as well as at distant pre-metastatic niches. A vital part of this communication network are small extracellular vesicles (sEVs, exosomes) with a size of 30–150 nm. Tumor-derived sEVs educate recipient cells with bioactive cargos, such as proteins, and in particular, major nucleic acid classes, to drive tumor growth, cell motility, angiogenesis, immune evasion and formation of pre-metastatic niches. Circulating sEVs are also utilized as biomarker platforms for diagnosis and prognosis. This review discusses how tumor cells facilitate progression through the metastatic cascade by employing sEV-based communication and evaluates their role as biomarkers and vehicles for drug delivery.

Challenges and Future Perspectives of Immunotherapy in Pancreatic Cancer

Simple Summary

Immunotherapeutic agents harness the patient’s immune system to fight cancer cells. Especially immune checkpoint inhibitors, a certain group of immunotherapeutic agents, have recently improved treatment options for many cancer types. Unfortunately, clinical trials testing of these agents in pancreatic cancer patients have not confirmed promising results from laboratory experiments. Several characteristics of pancreatic cancer biology, especially the profound tumour microenvironment that inhibits the successful identification and elimination of tumour cells by immune cells seems to be responsible for the lacking efficacy of immunotherapeutics in pancreatic cancer. We summarise recently published clinical trials investigating immunotherapeutic strategies in pancreatic cancer patients and available data on how these treatments influence pancreatic cancer biology. Moreover, we identify potential strategies to improve experimental and clinical studies in order to generate more conclusive data and improve patient outcomes in the future.

Abstract

To date, extensive efforts to harness immunotherapeutic strategies for the treatment of pancreatic ductal adenocarcinoma (PDAC) have yielded disappointing results in clinical trials. These strategies mainly focused on cancer vaccines and immune checkpoint inhibitors alone or in combination with chemotherapeutic or targeted agents. However, the growing preclinical and clinical data sets from these efforts have established valuable insights into the immunological characteristics of PDAC biology. Most notable are the immunosuppressive role of the tumour microenvironment (TME) and PDAC’s characteristically poor immunogenicity resulting from tumour intrinsic features. Moreover, PDAC tumour heterogeneity has been increasingly well characterized and may additionally limit a “one-fits-all” immunotherapeutic strategy. In this review, we first outline mechanisms of immunosuppression and immune evasion in PDAC. Secondly, we summarize recently published data on preclinical and clinical efforts to establish immunotherapeutic strategies for the treatment of PDAC including diverse combinatorial treatment approaches aiming at overcoming this resistance towards immunotherapeutic strategies. Particularly, these combinatorial treatment approaches seek to concomitantly increase PDAC antigenicity, boost PDAC directed T-cell responses, and impair the immunosuppressive character of the TME in order to allow immunotherapeutic agents to unleash their full potential. Eventually, the thorough understanding of the currently available data on immunotherapeutic treatment strategies of PDAC will enable researchers and clinicians to develop improved treatment regimens and to design innovative clinical trials to overcome the pronounced immunosuppression of PDAC.

Direct Endoplasmic Reticulum Targeting by the Selective Alkylphospholipid Analog and Antitumor Ether Lipid Edelfosine as a Therapeutic Approach in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC), the most common malignancy of the pancreas, shows a dismal and grim overall prognosis and survival rate, which have remained virtually unchanged for over half a century. PDAC is the most lethal of all cancers, with the highest mortality-to-incidence ratio. PDAC responds poorly to current therapies and remains an incurable malignancy. Therefore, novel therapeutic targets and drugs are urgently needed for pancreatic cancer treatment. Selective induction of apoptosis in cancer cells is an appealing approach in cancer therapy. Apoptotic cell death is highly regulated by different signaling routes that involve a variety of subcellular organelles. Endoplasmic reticulum (ER) stress acts as a double-edged sword at the interface of cell survival and death. Pancreatic cells exhibit high hormone and enzyme secretory functions, and thereby show a highly developed ER. Thus, pancreatic cancer cells display a prominent ER. Solid tumors have to cope with adverse situations in which hypoxia, lack of certain nutrients, and the action of certain antitumor agents lead to a complex interplay and crosstalk between ER stress and autophagy-the latter acting as an adaptive survival response. ER stress also mediates cell death induced by a number of anticancer drugs and experimental conditions, highlighting the pivotal role of ER stress in modulating cell fate. The alkylphospholipid analog prototype edelfosine is selectively taken up by tumor cells, accumulates in the ER of a number of human solid tumor cells-including pancreatic cancer cells-and promotes apoptosis through a persistent ER-stress-mediated mechanism both in vitro and in vivo. Here, we discuss and propose that direct ER targeting may be a promising approach in the therapy of pancreatic cancer, opening up a new avenue for the treatment of this currently incurable and deadly cancer. Furthermore, because autophagy acts as a cytoprotective response to ER stress, potentiation of the triggering of a persistent ER response by combination therapy, together with the use of autophagy blockers, could improve the current gloomy expectations for finding a cure for this type of cancer.

Pancreatic Cancer and Immunotherapy: A Clinical Overview

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with high mortality. The vast majority of patients present with unresectable, advanced stage disease, for whom standard of care chemo(radio)therapy may improve survival by several months. Immunotherapy has led to a fundamental shift in the treatment of several advanced cancers. However, its efficacy in PDAC in terms of clinical benefit is limited, possibly owing to the immunosuppressive, inaccessible tumor microenvironment. Still, various immunotherapies have demonstrated the capacity to initiate local and systemic immune responses, suggesting an immune potentiating effect. In this review, we address PDAC's immunosuppressive tumor microenvironment and immune evasion methods and discuss a wide range of immunotherapies, including immunomodulators (i.e., immune checkpoint inhibitors, immune stimulatory agonists, cytokines and adjuvants), oncolytic viruses, adoptive cell therapies (i.e., T cells and natural killer cells) and cancer vaccines. We provide a general introduction to their working mechanism as well as evidence of their clinical efficacy and immune potentiating abilities in PDAC. The key to successful implementation of immunotherapy in this disease may rely on exploitation of synergistic effects between treatment combinations. Accordingly, future treatment approaches should aim to incorporate diverse and novel immunotherapeutic strategies coupled with cytotoxic drugs and/or local ablative treatment, targeting a wide array of tumor-induced immune escape mechanisms.

Important role of Nfkb2 in the KrasG12D-driven carcinogenesis in the pancreas

BACKGROUND

Oncogenic Kras initiates and drives carcinogenesis in the pancreas by complex signaling networks, including activation of the NFκB pathway. Although recent evidence has shown that oncogenic gains in Nfκb2 collaborate with Kras in the carcinogenesis, no data at the level of genetics for the contribution of Nfκb2 is available so far.

METHODS

We used Nfkb2 knock-out mice to decipher the role of the gene in Kras-driven carcinogenesis in vivo.

RESULTS

We show that the Nfkb2 gene is needed for cancer initiation and progression in Kras^G12D-driven models and this requirement of Nfkb2 is mechanistically connected to proliferative pathways. In contrast, Nfκb2 is dispensable in aggressive pancreatic ductal adenocarcinoma (PDAC) models relying on the simultaneous expression of the Kras oncogene and the mutated tumor suppressor p53.

CONCLUSIONS

Our data add to the understanding of context-dependent requirements of oncogenic Kras signaling during pancreatic carcinogenesis.

GSK-3β in Pancreatic Cancer: Spotlight on 9-ING-41, Its Therapeutic Potential and Immune Modulatory Properties

Simple Summary

Glycogen synthase kinase-3 beta is a protein kinase implicated in the promotion and development of various cancers, including pancreatic cancer. In cell culture and animal studies, drugs targeting the inhibition of this protein show treatment potential in pancreatic cancer. Studies show targeting this protein for treatment may overcome resistance to conventional chemotherapy in pancreatic tumors. Early-stage clinical trials are currently studying small molecule inhibitors targeting glycogen synthase kinase-3 beta and interim results show favorable results. Recent studies also suggest that targeting this protein will create synergy with immunotherapy, such as checkpoint inhibitors. Future studies should aim to study new combination treatments involving glycogen synthase kinase-3 beta targeting drugs with chemotherapy and immunotherapy in pancreatic cancer.

Abstract

Glycogen synthase kinase-3 beta is a ubiquitously and constitutively expressed molecule with pleiotropic function. It acts as a protooncogene in the development of several solid tumors including pancreatic cancer through its involvement in various cellular processes including cell proliferation, survival, invasion and metastasis, as well as autophagy. Furthermore, the level of aberrant glycogen synthase kinase-3 beta expression in the nucleus is inversely correlated with tumor differentiation and survival in both in vitro and in vivo models of pancreatic cancer. Small molecule inhibitors of glycogen synthase kinase-3 beta have demonstrated therapeutic potential in pre-clinical models and are currently being evaluated in early phase clinical trials involving pancreatic cancer patients with interim results showing favorable results. Moreover, recent studies support a rationale for the combination of glycogen synthase kinase-3 beta inhibitors with chemotherapy and immunotherapy, warranting the evaluation of novel combination regimens in the future.

A quantitative score of immune cell infiltration predicts the prognosis in pancreatic ductal adenocarcinoma

Pancreatic Ductal Adenocarcinoma (PDAC) is characterized by an extensive and dense fibrous stroma, which plays an active role in tumor growth and metastasis. Despite the growing importance of the tumor microenvironment in PDAC prognosis, the immune cell infiltration landscape of PDAC has not been elucidated. In this study, we applied a credible computational algorithm to comprehensively estimate the immune cell infiltration (ICI) patterns of 876 PDAC patients. Two ICI phenotypes were identified, and a ICIscore was constructed using ssGSEA algorithm. The ICIscore could significantly predict the prognosis and chemotherapy benefit of PDAC patients in both the discovery and the five validation cohorts. Multivariate cox analysis also identified the independent predictive role of the ICIscore in PDAC prognosis. A high ICIscore subtype was characterized by immune-active signaling pathways and anti-tumor immunity while a low ICIscore subtype was associated with tumor progressive signaling pathways. Four immunotherapy cohorts further supported the use of the ICIscore as a prognostic biomarker for patients receiving immune checkpoint inhibitors in other cancer types. The ICIscore reveals a close relationship between the ICI environment and prognosis and may provide new treatment strategies for PDAC patients.

The Cellular and Biological Impact of Extracellular Vesicles in Pancreatic Cancer

Simple Summary

The increased incidence and global failure of ongoing therapies project pancreatic cancer as the second deadliest cancer worldwide. While our knowledge of pancreatic cancer cells’ abilities and specificities has drastically improved based on multi-scaled omics, one must consider that much more remains to be uncovered on the role and impact of stromal cells and the established network of communication with tumor cells. This review article discusses how tumor cells communicate with the various cells composing the stroma and its implication in tumor cells’ abilities, PDA (pancreatic ductal adenocarcinoma) carcinogenesis and therapeutic response. We will focus on extracellular vesicles-mediated crosstalk and how this multifaceted dialogue impacts both cellular compartments and its subsequent impact on PDA biology.

Abstract

Deciphering the interactions between tumor and stromal cells is a growing field of research to improve pancreatic cancer-associated therapies and patients’ care. Indeed, while accounting for 50 to 90% of the tumor mass, many pieces of evidence reported that beyond their structural role, the non-tumoral cells composing the intra-tumoral microenvironment influence tumor cells’ proliferation, metabolism, cell death and resistance to therapies, among others. Simultaneously, tumor cells can influence non-tumoral neighboring or distant cells in order to shape a tumor-supportive and immunosuppressive environment as well as influencing the formation of metastatic niches. Among intercellular modes of communication, extracellular vesicles can simultaneously transfer the largest variety of signals and were recently reported as key effectors of cell–cell communication in pancreatic cancer, from its development to its evolution as well as its ability to resist available treatments. This review focuses on extracellular vesicles-mediated communication between different cellular components of pancreatic tumors, from the modulation of cellular activities and abilities to their biological and physiological relevance. Taking into consideration the intra-tumoral microenvironment and its extracellular-mediated crosstalk as main drivers of pancreatic cancer development should open up new therapeutic windows.

Extracellular Vesicles and Pancreatic Cancer: Insights on the Roles of miRNA, lncRNA, and Protein Cargos in Cancer Progression

Pancreatic cancer (PC) is among the most devastating digestive tract cancers worldwide. This cancer is characterized by poor diagnostic detection, lack of therapy, and difficulty in predicting tumorigenesis progression. Although mutations of key oncogenes and oncosuppressor involved in tumor growth and in immunosurveillance escape are known, the underlying mechanisms that orchestrate PC initiation and progression are poorly understood or still under debate. In recent years, the attention of many researchers has been concentrated on the role of extracellular vesicles and of a particular subset of extracellular vesicles, known as exosomes. Literature data report that these nanovesicles are able to deliver their cargos to recipient cells playing key roles in the pathogenesis and progression of many pancreatic precancerous conditions. In this review, we have summarized and discussed principal cargos of extracellular vesicles characterized in PC, such as miRNAs, lncRNAs, and several proteins, to offer a systematic overview of their function in PC progression. The study of extracellular vesicles is allowing to understand that investigation of their secretion and analysis of their content might represent a new and potential diagnostic and prognostic tools for PC.

Does the Microenvironment Hold the Hidden Key for Functional Precision Medicine in Pancreatic Cancer?

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers and no significant improvement in patient survival has been seen in the past three decades. Treatment options are limited and selection of chemotherapy in the clinic is usually based on the performance status of a patient rather than the biology of their disease. In recent years, research has attempted to unlock a personalised treatment strategy by identifying actionable molecular targets in tumour cells or using preclinical models to predict the effectiveness of chemotherapy. However, these approaches rely on the biology of PDAC tumour cells only and ignore the importance of the microenvironment and fibrotic stroma. In this review, we highlight the importance of the microenvironment in driving the chemoresistant nature of PDAC and the need for preclinical models to mimic the complex multi-cellular microenvironment of PDAC in the precision medicine pipeline. We discuss the potential for ex vivo whole-tissue culture models to inform precision medicine and their role in developing novel therapeutic strategies that hit both tumour and stromal compartments in PDAC. Thus, we highlight the critical role of the tumour microenvironment that needs to be addressed before a precision medicine program for PDAC can be implemented.

Coagulation Signaling through PAR1 as a Therapeutic Target in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly fatal disease with a 5-year survival rate of less than 10% following diagnosis. The aggressive and invasive properties of pancreatic cancer tumors coupled with poor diagnostic options contribute to the high mortality rate since most patients present with late-stage disease. Accordingly, PDAC is linked to the highest rate of cancer-associated venous thromboembolic disease of all solid tumor malignancies. However, in addition to promoting clot formation, recent studies suggest that the coagulation system in PDAC mediates a reciprocal relationship, whereby coagulation proteases and receptors promote PDAC tumor progression and dissemination. Here, upregulation of tissue factor (TF) by tumor cells can drive local generation of the central coagulation protease thrombin that promotes cell signaling activity through protease-activated receptors (PARs) expressed by both tumor cells and multiple stromal cell subsets. Moreover, the TF-thrombin-PAR1 signaling axis appears to be a major mechanism of cancer progression in general and PDAC in particular. Here, we summarize the current literature regarding the role of PAR1 in PDAC and review possibilities for pharmacologically targeting PAR1 as a PDAC therapeutic approach.

Platelets, Constant and Cooperative Companions of Sessile and Disseminating Tumor Cells, Crucially Contribute to the Tumor Microenvironment

Although platelets and the coagulation factors are components of the blood system, they become part of and contribute to the tumor microenvironment (TME) not only within a solid tumor mass, but also within a hematogenous micrometastasis on its way through the blood stream to the metastatic niche. The latter basically consists of blood-borne cancer cells which are in close association with platelets. At the site of the primary tumor, the blood components reach the TME via leaky blood vessels, whose permeability is increased by tumor-secreted growth factors, by incomplete angiogenic sprouts or by vasculogenic mimicry (VM) vessels. As a consequence, platelets reach the primary tumor via several cell adhesion molecules (CAMs). Moreover, clotting factor VII from the blood associates with tissue factor (TF) that is abundantly expressed on cancer cells. This extrinsic tenase complex turns on the coagulation cascade, which encompasses the activation of thrombin and conversion of soluble fibrinogen into insoluble fibrin. The presence of platelets and their release of growth factors, as well as fibrin deposition changes the TME of a solid tumor mass substantially, thereby promoting tumor progression. Disseminating cancer cells that circulate in the blood stream also recruit platelets, primarily by direct cell-cell interactions via different receptor-counterreceptor pairs and indirectly by fibrin, which bridges the two cell types via different integrin receptors. These tumor cell-platelet aggregates are hematogenous micrometastases, in which platelets and fibrin constitute a particular TME in favor of the cancer cells. Even at the distant site of settlement, the accompanying platelets help the tumor cell to attach and to grow into metastases. Understanding the close liaison of cancer cells with platelets and coagulation factors that change the TME during tumor progression and spreading will help to curb different steps of the metastatic cascade and may help to reduce tumor-induced thrombosis.

Prognostic and Clinicopathological Significance of E-Cadherin in Pancreatic Cancer Patients: A Meta-Analysis

Background

Several recent studies have investigated the prognostic and clinicopathological significance of epithelial cadherin (E-cadherin) in pancreatic cancer; however, conclusions from these studies remain inconsistent. Therefore, we performed a meta-analysis to evaluate the effects of E-cadherin expression on the prognosis and clinicopathological characteristics of pancreatic cancer.

Methods

Embase, PubMed, and Web of Science were searched to identify articles associated with E-cadherin and pancreatic cancer. Hazard ratios (HRs) and odds ratios (ORs) with corresponding confidence intervals (CIs) were calculated and summarized. All eligible studies were searched until May 20, 2020. Heterogeneity among studies was assessed using the Chi-square test and I² statistic.

Results

Overall, 25 studies were identified, of which 12 reports with 1,032 cases concerned the prognosis of pancreatic cancer, and 22 involved the risk and clinical characteristics of pancreatic cancer. The overall results revealed that E-cadherin expression was significantly related to overall survival, gender, tumor grade, lymph node metastasis, tumor differentiation, and risk of pancreatic cancer. In the subgroup analysis, no significant heterogeneity or publication bias was observed.

Conclusions

E-cadherin expression is strongly associated with the risk, clinical features, and prognosis of pancreatic cancer, suggesting that E-cadherin may be an effective biomarker for the clinical assessments and predicting prognosis of pancreatic cancer.

Activated Regulatory T-Cells, Dysfunctional and Senescent T-Cells Hinder the Immunity in Pancreatic Cancer

Pancreatic cancer has one of the worst prognoses of any human malignancy and leukocyte infiltration is a major prognostic marker of the disease. As current immunotherapies confer negligible survival benefits, there is a need to better characterise leukocytes in pancreatic cancer to identify better therapeutic strategies. In this study, we analysed 32 human pancreatic cancer patients from two independent cohorts. A multi-parameter mass-cytometry analysis was performed on 32,000 T-cells from eight patients. Single-cell RNA sequencing dataset analysis was performed on a cohort of 24 patients. Multiplex immunohistochemistry imaging and spatial analysis were performed to map immune infiltration into the tumour microenvironment. Regulatory T-cell populations demonstrated highly immunosuppressive states with high TIGIT, ICOS and CD39 expression. CD8+ T-cells were found to be either in senescence or an exhausted state. The exhausted CD8 T-cells had low PD-1 expression but high TIGIT and CD39 expression. These findings were corroborated in an independent pancreatic cancer single-cell RNA dataset. These data suggest that T-cells are major players in the suppressive microenvironment of pancreatic cancer. Our work identifies multiple novel therapeutic targets that should form the basis for rational design of a new generation of clinical trials in pancreatic ductal adenocarcinoma.