Pancreatic ductal adenocarcinoma: Treatment hurdles, tumor microenvironment and immunotherapy

Targeting PI3K/AKT/mTOR Signaling Pathway in Pancreatic Cancer: From Molecular to Clinical Aspects

Although pancreatic cancer (PC) was considered in the past an orphan cancer type due to its low incidence, it may become in the future one of the leading causes of cancer death. Pancreatic ductal adenocarcinoma (PDAC) is the most frequent type of PC, being a highly aggressive malignancy and having a 5-year survival rate of less than 10%. Non-modifiable (family history, age, genetic susceptibility) and modifiable (smoking, alcohol, acute and chronic pancreatitis, diabetes mellitus, intestinal microbiota) risk factors are involved in PC pathogenesis. Chronic inflammation induced by various factors plays crucial roles in PC development from initiation to metastasis. In multiple malignant conditions such as PC, cytokines, chemokines, and growth factors activate the class I phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) (PI3K/AKT/mTOR) signaling pathway, which plays key roles in cell growth, survival, proliferation, metabolism, and motility. Currently, mTOR, AKT, and PI3K inhibitors are used in clinical studies. Moreover, PI3K/mTOR dual inhibitors are being tested in vitro and in vivo with promising results for PC patients. The main aim of this review is to present PC incidence, risk factors, tumor microenvironment development, and PI3K/AKT/mTOR dysregulation and inhibitors used in clinical, in vivo, and in vitro studies.

Focal adhesion kinase priming in pancreatic cancer, altering biomechanics to improve chemotherapy

The dense desmoplastic and fibrotic stroma is a characteristic feature of pancreatic ductal adenocarcinoma (PDAC), regulating disease progression, metastasis and response to treatment. Reciprocal interactions between the tumour and stroma are mediated by bidirectional integrin-mediated signalling, in particular by Focal Adhesion Kinase (FAK). FAK is often hyperactivated and overexpressed in aggressive cancers, promoting stromal remodelling and inducing tissue stiffness which can accelerate cancer cell proliferation, survival and chemoresistance. Therapeutic targeting of the PDAC stroma is an evolving area of interest for pre-clinical and clinical research, where a subtle reshaping of the stromal architecture prior to chemotherapy may prove promising in the clinical management of disease and overall patient survival. Here, we describe how transient stromal manipulation (or ‘priming’) via short-term FAK inhibition, rather than chronic treatment, can render PDAC cells exquisitely vulnerable to subsequent standard-of-care chemotherapy. We assess how our priming publication fits with the recent literature and describe in this perspective how this could impact future cancer treatment. This highlights the significance of treatment timing and warrants further consideration of anti-fibrotic therapies in the clinical management of PDAC and other fibrotic diseases.

Integrated analysis of senescence-associated genes in pancreatic ductal adenocarcinoma

Background: Cellular senescence plays a critical role in the occurrence and development, and immune modulation of cancer. This research primarily investigated the role of senescence-associated genes (SAGs) in the survival and tumor microenvironment of pancreatic ductal adenocarcinoma (PDAC).

Methods: From the Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) database, the gene expression profiles and clinical data of PDAC samples were downloaded. SAGs in the TCGA cohort were used to build a novel prognostic model and validated in the ICGC cohort. The relationship of signature with the immune landscape, tumor mutational burden (TMB), as well as the sensitivity of different therapies, was explored. Moreover, a nomogram was developed to predict the overall survival of PDAC patients.

Results: A prognostic signature was constructed on basis of three SAGs, and patients in the low-risk score group had a longer survival time. The accuracy of the signature to distinguish different score groups was confirmed through principal component analysis (PCA) and the Receiver operator curves curve. The mRNA expression of the three signature genes was also verified in normal pancreatic and PDAC cell lines by RT-qPCR. The signature could independently predict the prognosis of PDAC patients and had broad applicability. Meanwhile, the nomogram predicted that 1- and 3-years survival rates were in good agreement with the observed overall survival rates. Low-risk patients had lower tumor mutational burden, and low-TMB patients had a better prognosis. Low- and high-risk patients exhibit distinct immune cell infiltration and immune checkpoint changes. By further analyzing the risk score, patients in the low-risk group were more responsive to immunotherapy and a variety of commonly used chemotherapeutic drugs.

Conclusion: The prognostic signature can well predict the prognosis and assess the possibility of immunotherapy in personalized PDAC treatment.

Metabolic Pathways as a Novel Landscape in Pancreatic Ductal Adenocarcinoma

Metabolism plays a fundamental role in both human physiology and pathology, including pancreatic ductal adenocarcinoma (PDAC) and other tumors. Anabolic and catabolic processes do not only have energetic implications but are tightly associated with other cellular activities, such as DNA duplication, redox reactions, and cell homeostasis. PDAC displays a marked metabolic phenotype and the observed reduction in tumor growth induced by calorie restriction with in vivo models supports the crucial role of metabolism in this cancer type. The aggressiveness of PDAC might, therefore, be reduced by interventions on bioenergetic circuits. In this review, we describe the main metabolic mechanisms involved in PDAC growth and the biological features that may favor its onset and progression within an immunometabolic context. We also discuss the need to bridge the gap between basic research and clinical practice in order to offer alternative therapeutic approaches for PDAC patients in the more immediate future.

Cellular metabolism in pancreatic cancer as a tool for prognosis and treatment (Review)

Pancreatic cancer (PC) has one of the highest fatality rates and the currently available therapeutic options are not sufficient to improve its overall poor prognosis. In addition to insufficient effectiveness of anticancer treatments, the lack of clear early symptoms and early metastatic spread maintain the PC survival rates at a low level. Metabolic reprogramming is among the hallmarks of cancer and could be exploited for the diagnosis and treatment of PC. PC is characterized by its heterogeneity and, apart from molecular subtypes, the identification of metabolic subtypes in PC could aid in the development of more individualized therapeutic approaches and may lead to improved clinical outcomes. In addition to the deregulated utilization of glucose in aerobic glycolysis, PC cells can use a wide range of substrates, including branched‑chain amino acids, glutamine and lipids to fulfil their energy requirements, as well as biosynthetic needs. The tumor microenvironment in PC supports tumor growth, metastatic spread, treatment resistance and the suppression of the host immune response. Moreover, reciprocal interactions between cancer and stromal cells enhance their metabolic reprogramming. PC stem cells (PCSCs) with an increased resistance and distinct metabolic properties are associated with disease relapses and cancer spread, and represent another significant candidate for therapeutic targeting. The present review discusses the metabolic signatures observed in PC, a disease with a multifaceted and often transient metabolic landscape. In addition, the metabolic pathways utilized by PC cells, as well as stromal cells are discussed, providing examples of how they could present novel targets for therapeutic interventions and elaborating on how interactions between the various cell types affect their metabolism. Furthermore, the importance of PCSCs is discussed, focusing specifically on their metabolic adaptations.

Potential of Gold Nanoparticle in Current Radiotherapy Using a Co-Culture Model of Cancer Cells and Cancer Associated Fibroblast Cells

Simple Summary

Many cancer therapeutics do not account for the complexity of the tumor microenvironment (TME), which may result in failure when applied clinically. In this paper we utilized a simple tumor model made of two types of pancreatic cancer cells that contribute to the tumor environment, i.e., cancer cells and cancer associated fibroblasts. Herein, radiotherapy along with radiosensitizing gold nanoparticles were used to test the efficacy of a co-culture vs. monoculture model. The results show that the co-culture model exhibited heightened resistance to radiation. Furthermore, we found that the combination of gold radiosensitizers with radiotherapy reduced the radioresistance of the co-culture model compared to radiotherapy alone. This study demonstrates the potential of using nanotherapeutics in targeting the complex tumor microenvironment.

Abstract

Many cancer therapeutics are tested in vitro using only tumour cells. However, the tumour promoting effect of cancer associated fibroblasts (CAFs) within the tumour microenvironment (TME) is thought to reduce cancer therapeutics’ efficacy. We have chosen pancreatic ductal adenocarcinoma (PDAC) as our tumor model. Our goal is to create a co-culture of CAFs and tumour cells to model the interaction between cancer and stromal cells in the TME and allow for better testing of therapeutic combinations. To test the proposed co-culture model, a gold nanoparticle (GNP) mediated-radiation response was used. Cells were grown in co-culture with different ratios of CAFs to cancer cells. MIA PaCa-2 was used as our PDAC cancer cell line. Co-cultured cells were treated with 2 Gy of radiation following GNP incubation. DNA damage and cell proliferation were examined to assess the combined effect of radiation and GNPs. Cancer cells in co-culture exhibited up to a 23% decrease in DNA double strand breaks (DSB) and up to a 35% increase in proliferation compared to monocultures. GNP/Radiotherapy (RT) induced up to a 25% increase in DNA DSBs and up to a 15% decrease in proliferation compared to RT alone in both monocultured and co-cultured cells. The observed resistance in the co-culture system may be attributed to the role of CAFs in supporting cancer cells. Moreover, we were able to reduce the activity of CAFs using GNPs during radiation treatment. Indeed, CAFs internalize a significantly higher number of GNPs, which may have led to the reduction in their activity. One reason experimental therapeutics fail in clinical trials relates to limitations in the pre-clinical models that lack a true representation of the TME. We have demonstrated a co-culture platform to test GNP/RT in a clinically relevant environment.

Tumor microenvironment in pancreatic ductal adenocarcinoma: Implications in immunotherapy

Pancreatic ductal adenocarcinoma is one of the most aggressive and lethal cancers. Surgical resection is the only curable treatment option, but it is available for only a small fraction of patients at the time of diagnosis. With current therapeutic regimens, the average 5-year survival rate is less than 10% in pancreatic cancer patients. Immunotherapy has emerged as one of the most promising treatment options for multiple solid tumors of advanced stage. However, its clinical efficacy is suboptimal in most clinical trials on pancreatic cancer. Current studies have suggested that the tumor microenvironment is likely the underlying barrier affecting immunotherapy drug efficacy in pancreatic cancer. In this review, we discuss the role of the tumor microenvironment in pancreatic cancer and the latest advances in immunotherapy on pancreatic cancer.

MARK2 regulates chemotherapeutic responses through class IIa HDAC-YAP axis in pancreatic cancer

Despite paclitaxel's wide use in cancer treatment, patient response rate is still low and drug resistance is a major clinical obstacle. Through a Phos-tag-based kinome-wide screen, we identified MARK2 as a critical regulator for paclitaxel chemosensitivity in PDAC. We show that MARK2 is phosphorylated by CDK1 in response to antitubulin chemotherapeutics and in unperturbed mitosis. Phosphorylation is essential for MARK2 in regulating mitotic progression and paclitaxel cytotoxicity in PDAC cells. Mechanistically, our findings also suggest that MARK2 controls paclitaxel chemosensitivity by regulating class IIa HDACs. MARK2 directly phosphorylates HDAC4 specifically during antitubulin treatment. Phosphorylated HDAC4 promotes YAP activation and controls expression of YAP target genes induced by paclitaxel. Importantly, combination of HDAC inhibition and paclitaxel overcomes chemoresistance in organoid culture and preclinical PDAC animal models. The expression levels of MARK2, HDACs, and YAP are upregulated and positively correlated in PDAC patients. Inhibition of MARK2 or class IIa HDACs potentiates paclitaxel cytotoxicity by inducing mitotic abnormalities in PDAC cells. Together, our findings identify the MARK2-HDAC axis as a druggable target for overcoming chemoresistance in PDAC.

Ultrasound improved immune adjuvant delivery to induce DC maturation and T cell activation

Tumor immunotherapy has emerged as a promising approach to tumor treatment. Currently, immune adjuvant-based therapeutic modalities are rarely curative in solid tumors owing to challenges including the low permeability and extremely poor water solubility of these adjuvants, limiting their ability to effectively promote dendritic cell (DC) maturation. Herein, we employed ultrasound-mediated cavitation (UMC) to promote the delivery of Toll-like receptor agonist (R837)-loaded pH-responsive liposomes (PEOz-Lip@R837) to tumors. The tumor-associated antigens (TAAs) produced by UMC treatment exhibited vaccinal activity, particularly in the presence of immune adjuvants, together promoting the maturation of DC and inducing cytokine production. Importantly, UMC can down-regulate immune checkpoint molecules, like Cd274, Foxp3 and Ctla4, synergistically stimulating the activation and proliferation of T cells in the body to facilitate tumor treatment. This UMC-enhanced PEOz-Lip@R837 approach was able to induce a robust antitumor immune response capable of arresting primary and distant tumor growth, while also developing immunological memory, protecting against tumor rechallenge following initial tumor clearance. Overall, these results highlight a promising UMC- and pH-sensitive immune adjuvant delivery-based treatment for tumors with the potential for clinical application.

Exploring the metabolic landscape of pancreatic ductal adenocarcinoma cells using genome-scale metabolic modeling

Pancreatic ductal adenocarcinoma (PDAC) is a major research focus because of its poor therapy response and dismal prognosis. PDAC cells adapt their metabolism to the surrounding environment, often relying on diverse nutrient sources. Because traditional experimental techniques appear exhaustive to find a viable therapeutic strategy, a highly curated and omics-informed PDAC genome-scale metabolic model was reconstructed using patient-specific transcriptomics data. From the model-predictions, several new metabolic functions were explored as potential therapeutic targets in addition to the known metabolic hallmarks of PDAC. Significant downregulation in the peroxisomal beta oxidation pathway, flux modulation in the carnitine shuttle system, and upregulation in the reactive oxygen species detoxification pathway reactions were observed. These unique metabolic traits of PDAC were correlated with potential drug combinations targeting genes with poor prognosis in PDAC. Overall, this study provides a better understanding of the metabolic vulnerabilities in PDAC and will lead to novel effective therapeutic strategies.

The pancreatic cancer immune tumor microenvironment is negatively remodeled by gemcitabine while TGF-β receptor plus dual checkpoint inhibition maintains antitumor immune cells

Pancreatic ductal adenocarcinoma (PDA) tumors have a highly immunosuppressive desmoplastic tumor microenvironment (TME) where immune checkpoint inhibition (ICI) therapy has been exceptionally ineffective. Transforming growth factor-β (TGF-β) receptor activation leads to cancer and immune cell proliferation and phenotype, and cytokine production leading to tumor progression and worse overall survival in PDA patients. We hypothesized that TGF-β receptor inhibition may alter PDA progression and antitumor immunity in the TME. Here, we used a syngeneic preclinical murine model of PDA to explore the impact of TGF-β pathway inhibitor galunisertib (GAL), dual checkpoint immunotherapy (anti-PD-L1 and CTLA-4), the chemotherapy gemcitabine (GEM), and their combinations on antitumor immune responses. Blockade of TGF-β and ICI in immune-competent mice bearing orthotopically injected murine PDA cells significantly inhibited tumor growth and was accompanied by antitumor M1 macrophage infiltration. In contrast, GEM treatment resulted in increased PDA tumor growth, decreased antitumor M1 macrophages, and decreased cytotoxic CD8+ T cell subpopulation compared to control mice. Together, these findings demonstrate the ability of TGF-β inhibition with GAL to prime antitumor immunity in the TME and the curative potential of combining GAL with dual ICI. These preclinical results indicate that targeted inhibition of TGF-β may enhance the efficacy of dual immunotherapy in PDA. Optimal manipulation of the immune TME with non-ICI therapy may enhance therapeutic efficacy.

Scratching the Surface—An Overview of the Roles of Cell Surface GRP78 in Cancer

The 78 kDa glucose-regulated protein (GRP78) is considered an endoplasmic reticulum (ER)-resident molecular chaperone that plays a crucial role in protein folding homeostasis by regulating the unfolded protein response (UPR) and inducing numerous proapoptotic and autophagic pathways within the eukaryotic cell. However, in cancer cells, GRP78 has also been shown to migrate from the ER lumen to the cell surface, playing a role in several cellular pathways that promote tumor growth and cancer cell progression. There is another insidious consequence elicited by cell surface GRP78 (csGRP78) on cancer cells: the accumulation of csGRP78 represents a novel neoantigen leading to the production of anti-GRP78 autoantibodies that can bind csGRP78 and further amplify these cellular pathways to enhance cell growth and mitigate apoptotic cell death. This review examines the current body of literature that delineates the mechanisms by which ER-resident GRP78 localizes to the cell surface and its consequences, as well as potential therapeutics that target csGRP78 and block its interaction with anti-GRP78 autoantibodies, thereby inhibiting further amplification of cancer cell progression.

Divergent Roles of Mitochondria Dynamics in Pancreatic Ductal Adenocarcinoma

Simple Summary

Pancreatic ductal adenocarcinoma is one of the most lethal neoplasia due to the lack of early diagnostic markers and effective therapies. The study of metabolic alterations of PDAC is of crucial importance since it would open the way to the discovery of new potential therapies. Mitochondria represent key organelles that regulate energy metabolism, and they remodel their structure by undergoing modifications by fusing with other mitochondria or dividing to generate smaller ones. The alterations of mitochondria arrangement may influence the metabolism of PDAC cells, thus supporting the proliferative needs of cancer. Shedding light on this topic regarding cancer and, more specifically, PDAC may help identify new potential strategies that hit cancer cells at their “core,” i.e., mitochondria.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive tumors; it is often diagnosed at an advanced stage and is hardly treatable. These issues are strictly linked to the absence of early diagnostic markers and the low efficacy of treatment approaches. Recently, the study of the metabolic alterations in cancer cells has opened the way to important findings that can be exploited to generate new potential therapies. Within this scenario, mitochondria represent important organelles within which many essential functions are necessary for cell survival, including some key reactions involved in energy metabolism. These organelles remodel their shape by dividing or fusing themselves in response to cellular needs or stimuli. Interestingly, many authors have shown that mitochondrial dynamic equilibrium is altered in many different tumor types. However, up to now, it is not clear whether PDAC cells preferentially take advantage of fusion or fission processes since some studies reported a wide range of different results. This review described the role of both mitochondria arrangement processes, i.e., fusion and fission events, in PDAC, showing that a preference for mitochondria fragmentation could sustain tumor needs. In addition, we also highlight the importance of considering the metabolic arrangement and mitochondria assessment of cancer stem cells, which represent the most aggressive tumor cell type that has been shown to have distinctive metabolic features to that of differentiated tumor cells.

Combination of LIGHT (TNFSF14)-Armed Myxoma Virus Pre-Loaded into ADSCs and Gemcitabine in the Treatment of Experimental Orthotopic Murine Pancreatic Adenocarcinoma

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is a weakly immunogenic fatal neoplasm. Oncolytic viruses have dual anti-cancer properties including tumor-lysing and immune response-boosting effects and offer attractive alternative for PDAC management. Adipose-derived stem cells (AD-SCs) of mesenchymal origin were infected ex vivo with recombinant oncolytic myxoma virus (MYXV), which encodes murine LIGHT, also called tumor necrosis factor ligand superfamily member 14 (TNFSF14). ADSC-shielded virus were administered into murine pancreatic cancer lesions that had been induced orthotopically in immunocompetent mice. Ensuing oncolysis and the activation of anti-tumor immune responses provided significant survival benefit. Although adjunct therapy with gemcitabine improved the cytolytic killing of pancreatic cancer cells in vitro, it induced no additional survival advantage in this model in vivo.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a deadly neoplasm. Oncolytic viruses have tumorolytic and immune response-boosting effects and present great potential for PDAC management. We used LIGHT-armed myxoma virus (vMyx-LIGHT) loaded ex vivo into human adipose-derived mesenchymal stem cells (ADSCs) to evaluate murine PDAC treatment in conjunction with gemcitabine (GEM). The cytotoxicity of this treatment was confirmed in vitro using human and murine pancreatic cancer cell cultures, which were more sensitive to the combined approach and largely destroyed. Unlike cancer cells, ADSCs sustain significant viability after infection. The in vivo administration of vMyx-LIGHT-loaded ADSCs and gemcitabine was evaluated using immunocompetent mice with induced orthotopic PDAC lesions. The expression of virus-encoded LIGHT increased the influx of T cells to the tumor site. Shielded virus followed by gemcitabine improved tumor regression and survival. The addition of gemcitabine slightly compromised the adaptive immune response boost obtained with the shielded virus alone, conferring no survival benefit. ADSCs pre-loaded with vMyx-LIGHT allowed the effective transport of the oncolytic construct to PDAC lesions and yielded significant immune response; additional GEM administration failed to improve survival. In view of our results, the delivery of targeted/shielded virus in combination with TGF-β ablation and/or checkpoint inhibitors is a promising option to improve the therapeutic effects of vMyx-LIGHT/ADSCs against PDAC in vivo.

A Novel Sushi-IL15-PD1 CAR-NK92 Cell Line With Enhanced and PD-L1 Targeted Cytotoxicity Against Pancreatic Cancer Cells

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive and lethal malignancy with a limited response to current therapies. Novel and effective treatment is urgently needed. Herein, a chimeric antigen receptor (CAR)-NK92 cell line, with an interleukin (IL)-15Rα-sushi/IL-15 complex and a Programmed cell death-1(PD1) signal inverter was constructed and named SP (Sushi-IL15-PD1). We showed that CAR expression enabled SP cells to proliferate independently of IL-2 and became more resistant to nutrition starvation-induced apoptosis. Meanwhile, SP cells were more effective than NK92 in PDAC cell killing assays in vitro and in vivo, and there was a positive correlation between the killing capability of SP cells and PD-L1 expression in pancreatic cancer cells. Based on the synergistic and comprehensive effects of the special CAR structure, the adhesion, responsiveness, degranulation efficiency, targeted delivery of cytotoxic granule content, and cytotoxicity of SP cells were significantly stronger than those of NK92. In conclusion, the SP cell line is a promising adoptive immunotherapy cell line and has potential value as an adjuvant treatment for pancreatic cancer, especially in patients with high PD-L1 expression.

RelA Is an Essential Target for Enhancing Cellular Responses to the DNA Repair/Ref-1 Redox Signaling Protein and Restoring Perturbated Cellular Redox Homeostasis in Mouse PDAC Cells

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers with a poor response to current treatment regimens. The multifunctional DNA repair-redox signaling protein Ref-1 has a redox signaling function that activates several transcriptional factors (TFs) including NF-κB (RelA), STAT3, AP-1. These have been implicated in signaling in PDAC and associated with cancer progression and therapy resistance. Numerous studies have shown a role for RelA in PDAC inflammatory responses and therapy resistance, little is known as to how these inflammatory responses are modulated through Ref-1 redox signaling pathways during pancreatic pathogenesis. RelA and STAT3 are two major targets of Ref-1 and are important in PDAC pathogenesis. To decipher the mechanistic role of RelA in response to Ref-1 inhibition, we used PDAC cells (KC3590) from a genetically engineered Kras G12D-driven mouse model that also is functionally deficient for RelA (Parent/Vector) or KC3590 cells with fully functional RelA added back (clone 13; C13). We demonstrated that RelA deficient cells are more resistant to Ref-1 redox inhibitors APX3330, APX2009, and APX2014, and their sensitivity is restored in the RelA proficient cells. Knockdown of STAT3 did not change cellular sensitivity to Ref-1 redox inhibitors in either cell type. Gene expression analysis demonstrated that Ref-1 inhibitors significantly decreased IL-8, FOSB, and c-Jun when functional RelA is present. We also demonstrated that PRDX1, a known Ref-1 redox modulator, contributes to Ref-1 inhibitor cellular response. Knockdown of PRDX1 when functional RelA is present resulted in dramatically increased PDAC killing in response to Ref-1 inhibitors. The enhanced cell killing was not due to increased intracellular ROS production. Although Ref-1 inhibition decreased the NADP/NADPH ratio in the cells, the addition of PRDX1 knockdown did not further this redox imbalance. This data suggests that the mechanism of cell killing following Ref-1 inhibition is at least partially mediated through RelA and not STAT3. Further imbalancing of the redox signaling through disruption of the PRDX1-Ref-1 interaction may have therapeutic implications. Our data further support a pivotal role of RelA in mediating Ref-1 redox signaling in PDAC cells with the Kras G12D genotype and provide novel therapeutic strategies to combat PDAC drug resistance.

Preoperative Radiomics Approach to Evaluating Tumor-Infiltrating CD8+ T Cells in Patients With Pancreatic Ductal Adenocarcinoma Using Noncontrast Magnetic Resonance Imaging

BACKGROUND

CD8+ T cell in pancreatic ductal adenocarcinoma (PDAC) is closely related to the prognosis and treatment response of patients. Accurate preoperative CD8+ T-cell expression can better identify the population benefitting from immunotherapy.

PURPOSE

To develop and validate a machine learning classifier based on noncontrast magnetic resonance imaging (MRI) for the preoperative prediction of CD8+ T-cell expression in patients with PDAC.

STUDY TYPE

Retrospective cohort study.

POPULATION

Overall, 114 patients with PDAC undergoing MR scan and surgical resection; 97 and 47 patients in the training and validation cohorts. FIELD STRENGTH/SEQUENCE/3 T: Breath-hold single-shot fast-spin echo T2-weighted sequence and noncontrast T1-weighted fat-suppressed sequences.

ASSESSMENT

CD8+ T-cell expression was quantified using immunohistochemistry. For each patient, 2232 radiomics features were extracted from noncontrast T1- and T2-weighted images and reduced using the Wilcoxon rank-sum test and least absolute shrinkage and selection operator method. Linear discriminative analysis was used to construct radiomics and mixed models. Model performance was determined by its discriminative ability, calibration, and clinical utility.

STATISTICAL TESTS

Kaplan-Meier estimates, Student's t-test, the Kruskal-Wallis H test, and the chi-square test, receiver operating characteristic curve, and decision curve analysis.

RESULTS

A log-rank test showed that the survival duration in the CD8-high group (25.51 months) was significantly longer than that in the CD8-low group (22.92 months). The mixed model included all MRI characteristics and 13 selected radiomics features, and the area under the curve (AUC) was 0.89 (95% confidence interval [CI], 0.77-0.92) and 0.69 (95% CI, 0.53-0.82) in the training and validation cohorts. The radiomics model included 13 radiomics features, which showed good discrimination in the training cohort (AUC, 0.85; 95% CI, 0.77-0.92) and the validation cohort (AUC, 0.76; 95% CI, 0.61-0.87).

DATA CONCLUSIONS

This study developed a noncontrast MRI-based radiomics model that can preoperatively determine CD8+ T-cell expression in patients with PDAC and potentially immunotherapy planning.

EVIDENCE LEVEL

5 TECHNICAL EFFICACY: Stage 2.

Novel insight into pancreatic adenocarcinoma pathogenesis using liquid association analysis

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy associated with a poor prognosis. High-throughput disease-related-gene expression data provide valuable information on gene interaction, which consequently lead to deeper insight about pathogenesis. The co-expression analysis is a common approach that is used to investigate gene interaction. However, such an approach solely is inadequate to reveal the complexity of the gene interaction. The three-way interaction model is known as a novel approach applied to decode the complex relationship between genes.

METHODS

In the current study, the liquid association method was used to capture the statistically significant triplets involved in the PDAC pathogenesis. Subsequently, gene set enrichment and gene regulatory network analyses were performed to trace the biological relevance of the statistically significant triplets.

RESULTS

The results of the current study suggest that "response to estradiol" and "Regulation of T-cell proliferation" are two critical biological processes that may be associated with the PDAC pathogenesis. Additionally, we introduced six switch genes, namely Lamc2, Klk1, Nqo1, Aox1, Tspan1, and Cxcl12, which might be involved in PDAC triggering.

CONCLUSION

In the current study, for the first time, the critical genes and pathways involved in the PDAC pathogenesis were investigated using the three-way interaction approach. As a result, two critical biological processes, as well as six potential biomarkers, were suggested that might be involved in the PDAC triggering. Surprisingly, strong evidence for the biological relevance of our results can be found in the literature.

Identification of New Regulators of Pancreatic Cancer Cell Sensitivity to Oxaliplatin and Cisplatin

The chemoresistance of tumor cells is one of the most urgent challenges in modern oncology and in pancreatic cancer, in which this problem is the most prominent. Therefore, the identification of new chemosensitizing co-targets may be a path toward increasing chemotherapy efficacy. In this work, we performed high-performance in vitro knockout CRISPR/Cas9 screening to find potential regulators of the sensitivity of pancreatic cancer. For this purpose, MIA PaCa-2 cells transduced with two sgRNA libraries (“cell cycle/nuclear proteins genes” and “genome-wide”) were screened by oxaliplatin and cisplatin. In total, 173 candidate genes were identified as potential regulators of pancreatic cancer cell sensitivity to oxaliplatin and/or cisplatin; among these, 25 genes have previously been reported, while 148 genes were identified for the first time as potential platinum drug sensitivity regulators. We found seven candidate genes involved in pancreatic cancer cell sensitivity to both cisplatin and oxaliplatin. Gene ontology enrichment analysis reveals the enrichment of single-stranded DNA binding, damaged DNA binding pathways, and four associated with NADH dehydrogenase activity. Further investigation and validation of the obtained results by in vitro, in vivo, and bioinformatics approaches, as well as literature analysis, will help to identify novel pancreatic cancer platinum sensitivity regulators.

LGR5 expression and clinicopathological features of the invasive front in the fat infiltration area of pancreatic cancer

Background

Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) is a strong cancer stem cell marker in colorectal cancer; however, there are many unclear aspects of LGR5 expression in pancreatic cancer. It has been reported that the interaction between tumor cells and stroma at the fat infiltration site has a significant effect on pancreatic cancer prognosis. Therefore, we report a clinicopathological study of LGR5 expression at the fat invasion front in pancreatic cancer.

Methods

LGR5 expression was analyzed in 40 pancreatic ductal adenocarcinoma cases with RNAscope, which is a newly developed high-sensitivity in situ hybridization method. Epithelial-mesenchymal transition (EMT) was analyzed by the expression of E-cadherin and vimentin via immunohistochemistry.

Results

LGR5-positive dots were identified in all cases, especially with glandular formation. In the fat invasion front, a high histological grade showed significantly reduced LGR5 expression compared with a low histological grade (p=0.0126). LGR5 expression was significantly higher in the non-EMT phenotype group than in EMT phenotype group (p=0.0003). Additionally, LGR5 expression was significantly lower in cases with high vascular invasion than in those with low vascular invasion (p=0.0244).

Conclusions

These findings suggest that decreased LGR5 expression in the fat invasion front is associated with more aggressive biological behavior in pancreatic ductal adenocarcinoma, with higher tumor grade, EMT phenotype, and higher vascular invasion.

Association of facility type with overall survival in patients with nonsurgically managed pancreatic cancer

Aim: To investigate the association between receiving treatment at academic centers and overall survival in pancreatic ductal adenocarcinoma patients who do not receive definitive surgery of the pancreatic tumor. Methods: Using the National Cancer Database, patients who were diagnosed with pancreatic ductal adenocarcinoma between 2004 to 2016 were identified. Results: Of 262,209 patients, 101,003 (38.5%) received treatment at academic centers. In the multivariable Cox regression analysis, patients who received treatment at a nonacademic facility had significantly worse overall survival compared with patients who were treated at an academic center (hazard ratio: 1.279; 95% CI: 1.268-1.290; p = 0.001). Conclusion: Compared with treatment at academic centers, treatment at nonacademic centers was associated with significantly worse overall survival in patients with nonsurgically managed pancreatic ductal adenocarcinoma.

Pancreatic Ductal Adenocarcinoma Cortical Mechanics and Clinical Implications

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest cancers due to low therapeutic response rates and poor prognoses. Majority of patients present with symptoms post metastatic spread, which contributes to its overall lethality as the 4th leading cause of cancer-related deaths. Therapeutic approaches thus far target only one or two of the cancer specific hallmarks, such as high proliferation rate, apoptotic evasion, or immune evasion. Recent genomic discoveries reveal that genetic heterogeneity, early micrometastases, and an immunosuppressive tumor microenvironment contribute to the inefficacy of current standard treatments and specific molecular-targeted therapies. To effectively combat cancers like PDAC, we need an innovative approach that can simultaneously impact the multiple hallmarks driving cancer progression. Here, we present the mechanical properties generated by the cell’s cortical cytoskeleton, with a spotlight on PDAC, as an ideal therapeutic target that can concurrently attack multiple systems driving cancer. We start with an introduction to cancer cell mechanics and PDAC followed by a compilation of studies connecting the cortical cytoskeleton and mechanical properties to proliferation, metastasis, immune cell interactions, cancer cell stemness, and/or metabolism. We further elaborate on the implications of these findings in disease progression, therapeutic resistance, and clinical relapse. Manipulation of the cancer cell’s mechanical system has already been shown to prevent metastasis in preclinical models, but it has greater potential for target exploration since it is a foundational property of the cell that regulates various oncogenic behaviors.

Undifferentiated Sarcomatoid Carcinoma of the Pancreas: From Histology and Molecular Pathology to Precision Oncology

Undifferentiated sarcomatoid carcinoma of the pancreas (SCP) is a rare and aggressive subtype of pancreatic cancer. Histologically, SCP is a poorly differentiated tumor characterized by the lack of glandular differentiation and the presence of mesenchymal-like, spindle-shaped tumor cells. Due to its rarity, only sporadic cases have been reported, while its molecular characterization has not been sufficiently described. Surgical resection with curative intent is the gold-standard of SCP management, but this strategy is possible only in a small proportion of cases due to SCP early metastasization. Although SCP is generally associated with a poor prognosis, some clinical cases amenable to surgical resection and followed by adjuvant chemotherapy have demonstrated a remarkably long survival. Preliminary molecular insights on the SCP molecular landscape have demonstrated the recurrent presence of KRAS and TP53 mutations, highlighting genetic similarities with conventional pancreatic ductal adenocarcinoma (PDAC). Although the use of immunotherapy in PDAC remains an unmet challenge, recent insights indicated a potentially significant role of the PD-L1/Notch3 axis in SCP, opening new horizons for immunotherapy in this cancer subtype. In this review, we described the most important clinic-pathologic features of SCP, with a specific focus on their molecular landscape and the potential targets for precision oncology.

circular RNAs 0000515 and 0011385 as potential biomarkers for disease monitoring and determining prognosis in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is extremely fatal and potential biomarkers for precision medicine of patients with PDAC are yet to be elucidated. Moreover, the clinical values of circular RNAs (circRNAs) in PDAC management are yet to be investigated. The aim of the present study was to perform a secondary analysis of two PDAC public datasets (GSE69362 and GSE79634), to identify the candidate circRNAs, to validate the expression of these circRNAs, and to determine their association with the clinicopathological characteristics and survival of patients with PDAC. A total of 60 patients with PDAC were retrospectively reviewed in the present study. The expression levels of these candidate circRNAs were detected in PDAC tissues and paired adjacent normal tissues via reverse transcription-quantitative PCR analysis. In addition, the clinicopathological characteristics and overall survival (OS) of patients with PDAC were recorded. Bioinformatics analysis identified 22 overlapping differentially expressed (DE) circRNAs between the GSE69362 and GSE79634 datasets, among which nine DEcircRNAs with accordant expression trends (the DEcircRNAs that were upregulated or downregulated in tumor tissues compared with paired adjacent normal tissues in both datasets) were selected as candidate circRNAs, including circ_0000515, circ_0000517, circ_0000520, circ_0000514, circ_0011385, circ_0055033, circ_0072088, circ_0003528 and circ_0008514. In the 60 patients with PDAC, the expression levels of circ_0000515, circ_0000517, circ_0000520, circ_0000514, circ_0011385, circ_0055033, circ_0072088 and circ_0003528 were notably upregulated in PDAC tissues compared with paired adjacent normal tissues. Furthermore, circ_0000515, circ_0000520, circ_0000514, circ_0011385 and circ_0072088 were positively associated with T stage, N stage and/or TNM stage in patients with PDAC. Notably, circ_0000515 and circ_0011385 were negatively associated with OS in patients with PDAC. Taken together, the results of the present study suggest that circ_0000515 and circ_0011385 may serve as prognostic biomarkers for patients with PDAC.

Challenges in genomic analysis of model systems and primary tumors of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is characterized by aggressive tumor behavior and poor prognosis. Recent next-generation sequencing (NGS)-based genomic studies have provided novel treatment modes for pancreatic cancer via the identification of cancer driver variants and molecular subtypes in PDAC. Genome-wide approaches have been extended to model systems such as patient-derived xenografts (PDXs), organoids, and cell lines for pre-clinical purposes. However, the genomic characteristics vary in the model systems, which is mainly attributed to the clonal evolution of cancer cells during their construction and culture. Moreover, fundamental limitations such as low tumor cellularity and the complex tumor microenvironment of PDAC hinder the confirmation of genomic features in the primary tumor and model systems. The occurrence of these phenomena and their associated complexities may lead to false insights into the understanding of mechanisms and dynamics in tumor tissues of patients. In this review, we describe various model systems and discuss differences in the results based on genomics and transcriptomics between primary tumors and model systems. Finally, we introduce practical strategies to improve the accuracy of genomic analysis of primary tissues and model systems.

Modulated Electro-Hyperthermia Supports the Effect of Gemcitabine Both in Sensitive and Resistant Pancreas Adenocarcinoma Cell Lines

The poor prognosis of pancreatic ductal adenocarcinoma (PDAC) is frequently associated to high treatment resistance. Gemcitabine (GEM) alone or in combination is the most used chemotherapy for unresecable PDACs. Here we studied whether modulated electro-hyperthermia (mEHT), a non-invasive complementary treatment, can support the effect of GEM on PDAC cells in vitro. The LD20 for the GEM-resistant Panc1 cells proved to be 200× higher than for the drug-sensitive Capan1. The mEHT alone caused significant apoptosis in Capan1 cultures as confirmed by the elevated SubG1 phase cell fraction and increased number of cleaved Caspase-3 positive cells 48 h after treatment, with an additive effect when GEM was used after hyperthermia. These were accompanied by reduced number of G1, S, and G2/M phase cells and elevated expression of the cyclin-dependent kinase inhibitor p21waf1 protein. In GEM-resistant Panc1 cells, an initial apoptosis was detected by flow cytometry 24 h after mEHT ± GEM treatment, which however diminished by 48 h at persistent number of cleaved Caspase-3 positive tumor cells. Though GEM monotherapy reduced the number of tumor progenitor colonies in Capan1 cell line, an additive colony inhibitory effect of mEHT was observed after mEHT + GEM treatment. The heat shock induced Hsp27 and Hsp70 proteins, which are known to sensitize PDAC cells to GEM were upregulated in both Capan1 and Panc1 cells 24 h after mEHT treatment. The level of E-Cadherin, a cell adhesion molecule, increased in Capan1 cells after mEHT + GEM treatment. In conclusion, in GEM-sensitive PDAC cells mEHT treatment alone induced cell death and cell cycle inhibition and improved GEM efficiency in combination, which effects were milder and short-term up to 24 h in the GEM-resistant Panc1 cells. Our data further support the inclusion of hyperthermia, in particular of mEHT, into the traditional oncotherapy regimens of PDAC.

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.

IgE-Based Therapeutic Combination Enhances Antitumor Response in Preclinical Models of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) represents 3% of all cancer cases and 7% of all cancer deaths in the United States. Late diagnosis and inadequate response to standard chemotherapies contribute to an unfavorable prognosis and an overall 5-year survival rate of less than 10% in PDAC. Despite recent advances in tumor immunology, tumor-induced immunosuppression attenuates the immunotherapy response in PDAC. To date, studies have focused on IgG-based therapeutic strategies in PDAC. With the recent interest in IgE-based therapies in multiple solid tumors, we explored the MUC1-targeted IgE potential against pancreatic cancer. Our study demonstrates the notable expression of FceRI (receptor for IgE antibody) in tumors from PDAC patients. Our study showed that administration of MUC1 targeted-IgE (mouse/human chimeric anti-MUC1.IgE) antibody at intermittent levels in combination with checkpoint inhibitor (anti-PD-L1) and TLR3 agonist (PolyICLC) induces a robust antitumor response that is dependent on NK and CD8 T cells in pancreatic tumor-bearing mice. Subsequently, our study showed that the antigen specificity of the IgE antibody plays a vital role in executing the antitumor response as nonspecific IgE, induced by ovalbumin (OVA), failed to restrict tumor growth in pancreatic tumor-bearing mice. Utilizing the OVA-induced allergic asthma-PDAC model, we demonstrate that allergic phenotype induced by OVA cannot restrain pancreatic tumor growth in orthotopic tumor-bearing mice. Together, our data demonstrate the novel tumor protective benefits of tumor antigen-specific IgE-based therapeutics in a preclinical model of pancreatic cancer, which can open new avenues for future clinical interventions.

Emerging Role of miR-345 and Its Effective Delivery as a Potential Therapeutic Candidate in Pancreatic Cancer and Other Cancers

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with high mortality, poor prognosis, and palliative treatments, due to the rapid upregulation of alternative compensatory pathways and desmoplastic reaction. miRNAs, small non-coding RNAs, have been recently identified as key players regulating cancer pathogenesis. Dysregulated miRNAs are associated with molecular pathways involved in tumor development, metastasis, and chemoresistance in PDAC, as well as other cancers. Targeted treatment strategies that alter miRNA levels in cancers have promising potential as therapeutic interventions. miRNA-345 (miR-345) plays a critical role in tumor suppression and is differentially expressed in various cancers, including pancreatic cancer (PC). The underlying mechanism(s) and delivery strategies of miR-345 have been investigated by us previously. Here, we summarize the potential therapeutic roles of miR-345 in different cancers, with emphasis on PDAC, for miRNA drug discovery, development, status, and implications. Further, we focus on miRNA nanodelivery system(s), based on different materials and nanoformulations, specifically for the delivery of miR-345.

Distinct Survival Outcomes in Subgroups of Stage III Pancreatic Cancer Patients: Taiwan Cancer Registry and Surveillance, Epidemiology and End Results registry

Purpose

Pancreatic cancer is one of the most malignant cancers with poor survival. The latest edition of the American Joint Committee on Cancer (AJCC) staging system classifies the majority of operable pancreatic cancer patients as stage-III, while dramatic heterogeneity is observed among these patients. Therefore, subgrouping is required to accurately predict their prognosis and define a treatment plan. This study conducts a cohort study to provide a more precise classification system for stage-III pancreatic cancer patients by utilizing clinical variables.

Methods

We analyzed survival using log-rank tests, univariate Cox-regression models, and Kaplan-Meier survival curves for stage-III pancreatic ductal adenocarcinoma (PDAC) patients from the Taiwan Cancer Registry (TCR). Patients were further divided into subgroups using classification and regression tree (CART) algorithm. All results were validated using the SEER database.

Results

Among stage-III PDAC patients, lymph node and tumor grade showed significant association with survival. Patients with N2 stage had higher mortality risks (hazard ratio [HR] = 2.30, 95% confidence interval [CI] 1.71–3.08, p < 0.0001) than N0 patients. Patients with grade 3 also had higher risk of mortality (HR = 3.80, 95% CI 2.25–6.39, p < 0.0001) than grade 1 patients. The CART algorithm stratified stage-III patients into four subgroups with significantly different survival rates. The median survival of the four subgroups was 23.5, 18.4, 14.5, and 9.0 months, respectively (p < 0.0001). Similar results were observed with SEER data.

Conclusions

Lymph node involvement and tumor grade are predictive factors for survival in stage-III PDAC patients. This new precise classification system can be used to guide treatment planning in advanced-stage pancreatic cancer.

Supplementary Information

The online version contains supplementary material available at 10.1245/s10434-021-11030-w.

DPP inhibition alters the CXCR3 axis and enhances NK and CD8+ T cell infiltration to improve anti-PD1 efficacy in murine models of pancreatic ductal adenocarcinoma

Background

Pancreatic ductal adenocarcinoma (PDAC) is projected to be the second leading cause of cancer death in the USA by 2030. Immune checkpoint inhibitors fail to control most PDAC tumors because of PDAC’s extensive immunosuppressive microenvironment and poor immune infiltration, a phenotype also seen in other non-inflamed (ie, ‘cold’) tumors. Identifying novel ways to enhance immunotherapy efficacy in PDAC is critical. Dipeptidyl peptidase (DPP) inhibition can enhance immunotherapy efficacy in other cancer types; however, the impact of DPP inhibition on PDAC tumors remains unexplored.

Methods

We examined the effects of an oral small molecule DPP inhibitor (BXCL701) on PDAC tumor growth using mT3-2D and Pan02 subcutaneous syngeneic murine models in C57BL/6 mice. We explored the effects of DPP inhibition on the tumor immune landscape using RNAseq, immunohistochemistry, cytokine evaluation and flow cytometry. We then tested if BXCL701 enhanced anti-programmed cell death protein 1 (anti-PD1) efficacy and performed immune cell depletion and rechallenged studies to explore the relevance of cytotoxic immune cells to combination treatment efficacy.

Results

In both murine models of PDAC, DPP inhibition enhanced NK and T cell immune infiltration and reduced tumor growth. DPP inhibition also enhanced the efficacy of anti-PD1. The efficacy of dual anti-PD1 and BXCL701 therapy was dependent on both CD8+ T cells and NK cells. Mice treated with this combination therapy developed antitumor immune memory that cleared some tumors after re-exposure. Lastly, we used The Cancer Genome Atlas (TCGA) to demonstrate that increased NK cell content, but not T cell content, in human PDAC tumors is correlated with longer overall survival. We propose that broad DPP inhibition enhances antitumor immune response via two mechanisms: (1) DPP4 inhibition increases tumor content of CXCL9/10, which recruits CXCR3+ NK and T cells, and (2) DPP8/9 inhibition activates the inflammasome, resulting in proinflammatory cytokine release and Th1 response, further enhancing the CXCL9/10-CXCR3 axis.

Conclusions

These findings show that DPP inhibition with BXCL701 represents a pharmacologic strategy to increase the tumor microenvironment immune cell content to improve anti-PD1 efficacy in PDAC, suggesting BXCL701 can enhance immunotherapy efficacy in ‘cold’ tumor types. These findings also highlight the potential importance of NK cells along with T cells in regulating PDAC tumor growth.

Cell death in pancreatic cancer: from pathogenesis to therapy

Pancreatic cancer is a devastating gastrointestinal cancer characterized by late diagnosis, limited treatment success and dismal prognosis. Exocrine tumours account for 95% of pancreatic cancers and the most common pathological type is pancreatic ductal adenocarcinoma (PDAC). The occurrence and progression of PDAC involve multiple factors, including internal genetic alterations and external inflammatory stimuli. The biology and therapeutic response of PDAC are further shaped by various forms of regulated cell death, such as apoptosis, necroptosis, ferroptosis, pyroptosis and alkaliptosis. Cell death induced by local or systemic treatments suppresses tumour proliferation, invasion and metastasis. However, unrestricted cell death or tissue damage might result in an inflammation-related immunosuppressive microenvironment, which is conducive to tumour progression or recurrence. The precise extent to which cell death affects PDAC is not yet well described. A growing body of preclinical and clinical studies document significant correlations between mutations (for example, in KRAS and TP53), stress responses (such as hypoxia and autophagy), metabolic reprogramming and chemotherapeutic responses. Here, we describe the molecular machinery of cell death, discuss the complexity and multifaceted nature of lethal signalling in PDAC cells, and highlight the challenges and opportunities for activating cell death pathways through precision oncology treatments.

CGAT: Cell Graph ATtention Network for Grading of Pancreatic Disease Histology Images

Early detection of Pancreatic Ductal Adenocarcinoma (PDAC), one of the most aggressive malignancies of the pancreas, is crucial to avoid metastatic spread to other body regions. Detection of pancreatic cancer is typically carried out by assessing the distribution and arrangement of tumor and immune cells in histology images. This is further complicated due to morphological similarities with chronic pancreatitis (CP), and the co-occurrence of precursor lesions in the same tissue. Most of the current automated methods for grading pancreatic cancers rely on extensive feature engineering involving accurate identification of cell features or utilising single number spatially informed indices for grading purposes. Moreover, sophisticated methods involving black-box approaches, such as neural networks, do not offer insights into the model's ability to accurately identify the correct disease grade. In this paper, we develop a novel cell-graph based Cell-Graph Attention (CGAT) network for the precise classification of pancreatic cancer and its precursors from multiplexed immunofluorescence histology images into the six different types of pancreatic diseases. The issue of class imbalance is addressed through bootstrapping multiple CGAT-nets, while the self-attention mechanism facilitates visualization of cell-cell features that are likely responsible for the predictive capabilities of the model. It is also shown that the model significantly outperforms the decision tree classifiers built using spatially informed metric, such as the Morisita-Horn (MH) indices.

Serum Metabolomic and Lipoprotein Profiling of Pancreatic Ductal Adenocarcinoma Patients of African Ancestry

Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer with a characteristic dysregulated metabolism. Abnormal clinicopathological features linked to defective metabolic and inflammatory response pathways can induce PDAC development and progression. In this study, we investigated the metabolites and lipoproteins profiles of PDAC patients of African ancestry. Nuclear Magnetic Resonance (NMR) spectroscopy was conducted on serum obtained from consenting individuals (34 PDAC, 6 Chronic Pancreatitis, and 6 healthy participants). Seventy-five signals were quantified from each NMR spectrum. The Liposcale test was used for lipoprotein characterization. Spearman's correlation and Kapan Meier tests were conducted for correlation and survival analyses, respectively. In our patient cohort, the results demonstrated that levels of metabolites involved in the glycolytic pathway increased with the tumour stage. Raised ethanol and 3-hydroxybutyrate were independently correlated with a shorter patient survival time, irrespective of tumour stage. Furthermore, increased levels of bilirubin resulted in an abnormal lipoprotein profile in PDAC patients. Additionally, we observed that the levels of a panel of metabolites (such as glucose and lactate) and lipoproteins correlated with those of inflammatory markers. Taken together, the metabolic phenotype can help distinguish PDAC severity and be used to predict patient survival and inform treatment intervention.

GSK3β as a novel promising target to overcome chemoresistance in pancreatic cancer

Pancreatic cancer is an aggressive malignancy with increasing incidence and poor prognosis due to its late diagnosis and intrinsic chemoresistance. Most pancreatic cancer patients present with locally advanced or metastatic disease characterized by inherent resistance to chemotherapy. These features pose a series of therapeutic challenges and new targets are urgently needed. Glycogen synthase kinase 3 beta (GSK3β) is a conserved serine/threonine kinase, which regulates key cellular processes including cell proliferation, DNA repair, cell cycle progression, signaling and metabolic pathways. GSK3β is implicated in non-malignant and malignant diseases including inflammation, neurodegenerative diseases, diabetes and cancer. GSK3β recently emerged among the key factors involved in the onset and progression of pancreatic cancer, as well as in the acquisition of chemoresistance. Intensive research has been conducted on key oncogenic functions of GSK3β and its potential as a druggable target; currently developed GSK3β inhibitors display promising results in preclinical models of distinct tumor types, including pancreatic cancer. Here, we review the latest findings about GSK-3β biology and its role in the development and progression of pancreatic cancer. Moreover, we discuss therapeutic agents targeting GSK3β that could be administered as monotherapy or in combination with other drugs to surmount chemoresistance. Several studies are also defining potential gene signatures to identify patients who might benefit from GSK3β-based therapeutic intervention. This detailed overview emphasizes the urgent need of additional molecular studies on the impact of GSK3β inhibition as well as structural analysis of novel compounds and omics studies of predictive biomarkers.

Biological Hallmarks and New Therapeutic Approaches for the Treatment of PDAC

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the deadliest solid tumors and is estimated to become a leading cause of cancer-related death in coming years. Despite advances in surgical approaches and the emergence of new chemotherapy options, its poor prognosis has not improved in the last decades. The current treatment for PDAC is the combination of cytotoxic chemotherapy agents. However, PDAC shows resistance to many antineoplastic therapies with rapid progression. Although PDAC represents a heterogeneous disease, there are common alterations including oncogenic mutations of KRAS, and the frequent inactivation of different cell cycle regulators including the CDKN2A tumor suppressor gene. An emerging field of investigation focuses on inhibiting the function of proteins that suppress the immune checkpoint PD-1/PD-L1, with activation of the endogenous immune response. To date, all conventional immunotherapies have been less successful in patients with PDAC compared to other tumors. The need for new targets, associated with an extended molecular analysis of tumor samples could give new pharmacological options for the treatment of PDAC. It is, therefore, important to push for a broader molecular approach in PDAC research. Here, we provide a selected summary of emerging strategy options for targeting PDAC using CDK4/6 inhibitors, RAS inhibitors, and new drug combinations with immune checkpoint agents.

Targeting DNA damage repair pathways in pancreas cancer

Pancreas ductal adenocarcinoma (PDAC) is the third most common cause of cancer death in the USA. While other cancers with historically poor prognoses have benefited from new immunotherapies and targeted agents, the 5-year survival rate for PDAC patients has remained static. The accessibility to genomic testing has improved in recent years, and it is now clear that PDAC is a heterogenous disease, with a subset of patients harboring actionable mutations. There are several targeted therapies approved by the Food and Drug administration (FDA) in PDAC: EGFR inhibitor erlotinib (combined with gemcitabine) in unselected patients, TRK inhibitors larotrectinib and entrectinib for patients with NTRK fusion mutation, the PD-1 inhibitor pembrolizumab for mismatch repair-deficient patients, and the poly-ADP-ribose polymerase (PARP) inhibitor olaparib in patients with germline BRCA mutation as a maintenance therapy. DNA damage repair (DDR) is paramount to genomic integrity and cell survival. The defective repair of DNA damage is one of the hallmarks of cancer, and abnormalities in DDR pathways are closely linked with the development of malignancies and upregulation of these pathways linked with resistance to treatment. The prevalence of somatic and germline mutations in DDR pathways in metastatic PDAC is reported to be approximately 15-25%. Patients with DDR gene alterations benefit from a personalized approach to treatment. Recently, the POLO trial demonstrated a progression-free survival (PFS) benefit in metastatic PDAC patients with a germline BRCA1/2 mutation treated with maintenance olaparib following platinum-based induction chemotherapy. This was the first phase 3 randomized trial to establish a biomarker-driven approach in the treatment of PDAC and establishes a precedent for maintenance therapy in PDAC. The review herein aims to outline the current treatment landscape for PDAC patients with DDR gene-mutated tumors, highlight novel therapeutic approaches focused on surmounting tumor resistance, and explore new strategies which may lead to an expansion in the number of patients who benefit from these targeted treatments.

Targeting the Stroma in the Management of Pancreatic Cancer

Pancreatic cancer (PC) presents extremely aggressive tumours and is associated with poor survival. This is attributed to the unique features of the tumour microenvironment (TME), which is known to create a dense stromal formation and poorly immunogenic condition. In particular, the TME of PC, including the stromal cells and extracellular matrix, plays an essential role in the progression and chemoresistance of PC. Consequently, several promising agents that target key components of the stroma have already been developed and are currently in multiple stages of clinical trials. Therefore, the authors review the latest available evidence on novel stroma-targeting approaches, highlighting the potential impact of the stroma as a key component of the TME in PC.

Combinatorial Treatment of Tinzaparin and Chemotherapy Can Induce a Significant Antitumor Effect in Pancreatic Cancer

Pancreatic Cancer (PC) is recognized as a highly thrombogenic tumor; thus, low-molecular-weight heparin (LMWH) such as tinzaparin is routinely used for PC patients. On the basis of combinatorial therapy approaches to treat highly malignant and refractory cancers such as PC, we hypothesized that tinzaparin can augment the effectiveness of traditional chemotherapeutic drugs and induce efficient antitumor activity. PANC-1 and MIAPaCa-2 were incubated alone or in combination with tinzaparin, nab-paclitaxel and gemcitabine. In vivo evaluation of these compounds was performed in a NOD/SCID mouse using a model injected with PANC-1. Tinzaparin enhances the anti-tumor effects of nab-paclitaxel and gemcitabine in mtKRAS PC cell lines via apoptosis in in vitro experiments. The triple combination power acts through the induction of apoptosis, reduction of the proliferative potential and angiogenesis; hence, contributing to a decrease in tumor volume observed in vivo. The triple regimen provided an extra 24.3% tumor reduction compared to the double combination (gemcitabine plus nab-paclitaxel). Combinatorial strategies can create novel therapeutic approaches for the treatment of patients with PC, achieving a better clinical outcome and prolonged survival. Further prospective randomized research is needed and the investigation of various concentrations of tinzaparin above 150 UI/Kg, would potentially provide a valuable synergistic effect to the conventional therapeutic compounds.

Integrative Management of Pancreatic Cancer (PDAC): Emerging Complementary Agents and Modalities

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease. The standard first-line treatment for PDAC is gemcitabine chemotherapy which, unfortunately, offers only limited chance of a lasting cure. This review further evaluates the hypothesis that the effectiveness of gemcitabine can be improved by combining it with evidence-based complementary measures. Previously, supported by clinical trial data, we suggested that a number of dietary factors and nutraceuticals can be integrated with gemcitabine therapy. Here, we evaluate a further 10 agents for which no clinical trials have (yet) been carried out but there are promising data from in vivo and/or in vitro studies including experiments involving combined treatments with gemcitabine. Two groups of complementary agents are considered: Dietary factors (resveratrol, epigallocatechin gallate, vitamin B9, capsaicin, quercetin and sulforaphane) and nutraceutical agents (artemisinin, garcinol, thymoquinone and emodin). In addition, we identified seven promising agents for which there is currently only basic (mostly in vitro) data. Finally, as a special case of combination therapy, we highlighted synergistic drug combinations involving gemcitabine with "repurposed" aspirin or metformin. We conclude overall that integrated management of PDAC currently is likely to produce the best outcome for patients and for this a wide range of complementary measures is available.

Margin ACcentuation for resectable Pancreatic cancer using Irreversible Electroporation - Results from the MACPIE-I study

INTRODUCTION

Margin accentuation (MA) using Irreversible electroporation (IRE) offers an unique opportunity to reduce the R1 resections in resectable pancreatic cancer (RPC). This study aims to assess the rate of margin positivity using IRE for MA during pancreaticoduodenectomy (PD) for resectable pancreatic head tumours.

MATERIALS AND METHODS

Following ethical approval, MA using IRE was carried out in 20 consecutive patients to posterior and superior mesenteric vein (SMV) margin, and the pancreatic neck, prior to the PD resection. The control group (non-IRE; n = 91) underwent PD without MA over the study period, March 2018 to March 2020.

RESULTS

There was no difference between the two groups in terms of patients' age, gender, pre-op biliary drainage, site of malignancy or pre-operative TNM stage. The overall margin positive rate for IRE group was lesser (35.0%) when compared to non-IRE group (51.6%; p = 0.177), with significantly less posterior pancreatic margin positivity (5.0% vs. 25.3%; p = 0.046). When only treated margins (SMA margin excluded) were compared, the IRE group had significantly lower margin positive rates (20.0% vs. 51.6%; p = 0.013). There was no difference between the two groups in terms of intra- or post-operative complications. With a median follow-up of 15.6 months, the median DFS and OS for IRE and non-IRE groups were 17 and 18 months (p = 0.306) and 19 and 22 months (p = 0.227) respectively.

CONCLUSION

Our pilot study confirms the safety of MA using IRE for RPC, with reduction in margin positivity. These results as a proof of concept are promising and need further validation with a randomised controlled trial.

Current Challenges for IDO2 as Target in Cancer Immunotherapy

Immune checkpoint inhibitors have revolutionized the clinical approach of untreatable tumors and brought a breath of fresh air in cancer immunotherapy. However, the therapeutic effects of these drugs only cover a minority of patients and alternative immunotherapeutic targets are required. Metabolism of l-tryptophan (Trp) via the kynurenine pathway represents an important immune checkpoint mechanism that controls adaptive immunity and dampens exaggerated inflammation. Indoleamine 2,3-dioxygenase 1 (IDO1), the enzyme catalyzing the first, rate–limiting step of the pathway, is expressed in several human tumors and IDO1 catalytic inhibitors have reached phase III clinical trials, unfortunately with disappointing results. Although much less studied, the IDO1 paralog IDO2 may represent a valid alternative as drug target in cancer immunotherapy. Accumulating evidence indicates that IDO2 is much less effective than IDO1 in metabolizing Trp and its functions are rather the consequence of interaction with other, still undefined proteins that may vary in distinct inflammatory and neoplastic contexts. As a matter of fact, the expression of IDO2 gene variants is protective in PDAC but increases the risk of developing tumor in NSCLC patients. Therefore, the definition of the IDO2 interactome and function in distinct neoplasia may open innovative avenues of therapeutic interventions.

Characterization of the tumor immune-microenvironment of adenocarcinoma of lung with a metastatic lesion in the pancreas treated successfully with first-line, single-agent pembrolizumab

Single-agent immune checkpoint inhibitor therapy in advanced non-small cell lung cancer can significantly prolong progression-free and overall survival when compared with cytotoxic chemotherapy. Here, we report a case of newly diagnosed adenocarcinoma of the lung with a solitary brain metastasis and a biopsy confirmed adenocarcinoma in the tail of the pancreas. Cytomorphology and immunohistochemistry suggested the lung and pancreas tumors were distinct primaries. However, molecular analysis of the lung primary and tumor in the pancreas revealed the same mutations of functional significance in PIK3CA, NF1 and TP53, suggesting the tumors were clonal. A total of three cycles of single-agent pembrolizumab, and radiation to the lung and brain administered between cycles 1 and 2, resulted in marked responses in lung, brain and pancreatic tumors. Despite the discontinuation of the pembrolizumab after three cycles due to severe immune-mediated toxicities, the patient has had no progression 11 months after stopping all active treatment. Results of a novel 27-gene immuno-oncology (IO) expression assay revealed strong IO scores for the lung and pancreatic tumors, indicating a favorable tumor immune-microenvironment and possibly explaining the significant response.

Unfolding antifungals: as a new foe to pancreatic ductal adenocarcinoma-a mini-review

Increased deaths caused due to pancreatic cancer (PC) is drawing much attention towards an immediate need for therapeutics that could possibly control this disease and increase the patients' survival rate. Despite the long list of well-established chemotherapeutic drugs in several cancers none have proved to be efficient against PC, and the increasing chemoresistance to the gold standard drug gemcitabine calls a need to search for solutions in other categories of drug. To the rescue, antifungals have shown themselves to be effective against PC and can increase gemcitabine sensitivity against PC. In this mini-review, we reported how antifungals have targeted PC and helped to reduce its lethality. Additionally, it is emphasized that how the antifungals show new mechanisms that could be triggered by using either monotherapy or combination therapy of these antifungals with chemotherapeutic drugs in PC. Moreover it shows an approach of using other drugs with possible same or other mechanism to know their effect on PC.

3d tissue models as tools for radiotherapy screening for pancreatic cancer

The efficiency of radiotherapy treatment regimes varies from tumour to tumour and from patient to patient but it is generally highly influenced by the tumour microenvironment (TME). The TME can be described as a heterogeneous composition of biological, biophysical, biomechanical and biochemical milieus that influence the tumour survival and its' response to treatment. Preclinical research faces challenges in the replication of these in vivo milieus for predictable treatment response studies. 2D cell culture is a traditional, simplistic and cost-effective approach to culture cells in vitro, however, the nature of the system fails to recapitulate important features of the TME such as structure, cell-cell and cell-matrix interactions. At the same time, the traditional use of animals (Xenografts) in cancer research allows realistic in vivo architecture, however foreign physiology, limited heterogeneity and reduced tumour mutation rates impairs relevance to humans. Furthermore, animal research is very time consuming and costly. Tissue engineering is advancing as a promising biomimetic approach, producing 3D models that capture structural, biophysical, biochemical and biomechanical features, therefore, facilitating more realistic treatment response studies for further clinical application. However, currently, the application of 3D models for radiation response studies is an understudied area of research, especially for pancreatic ductal adenocarcinoma (PDAC), a cancer with a notoriously complex microenvironment. At the same time, specific novel and/or more enhanced radiotherapy tumour-targeting techniques such as MRI-guided radiotherapy and proton therapy are emerging to more effectively target pancreatic cancer cells. However, these emerging technologies may have different biological effectiveness as compared to established photon-based radiotherapy. For example, for MRI-guided radiotherapy, the novel use of static magnetic fields (SMF) during radiation delivery is understudied and not fully understood. Thus, reliable biomimetic platforms to test new radiation delivery strategies are required to more accurately predict in vivo responses. Here, we aim to collate current 3D models for radiation response studies of PDAC, identifying the state of the art and outlines knowledge gaps. Overall, this review paper highlights the need for further research on the use of 3D models for pre-clinical radiotherapy screening including (i) 3D (re)-modeling of the PDAC hypoxic TME to allow for late effects of ionising radiation (ii) the screening of novel radiotherapy approaches and their combinations as well as (iii) a universally accepted 3D-model image quantification method for evaluating TME components in situ that would facilitate accurate post-treatment(s) quantitative comparisons.

NUCB1 Suppresses Growth and Shows Additive Effects With Gemcitabine in Pancreatic Ductal Adenocarcinoma via the Unfolded Protein Response

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer with poor patient prognosis. A cellular stress response mechanism called the unfolded protein response (UPR) has been implicated in PDAC progression. More recently, nucleobindin 1 (NUCB1), a calcium-binding protein, has been shown to control the UPR but its precise role in PDAC has not been explored. Here, we found that downregulation of NUCB1 was associated with poor prognosis in patients with PDAC. Functionally, NUCB1 overexpression suppressed pancreatic cancer cell proliferation and showed additive effects with gemcitabine (GEM) in vitro and in vivo. Moreover, by controlling ATF6 activity, NUCB1 overexpression suppressed GEM-induced UPR and autophagy. Last but not least, we uncovered METTL3-mediated m⁶A modification on NUCB1 5'UTR via the reader YTHDF2 as a mechanism for NUCB1 downregulation in PDAC. Taken together, our study revealed crucial functions of NUCB1 in suppressing proliferation and enhancing the effects of gemcitabine in pancreatic cancer cells and identified METTL3-mediated m⁶A modification as a mechanism for NUCB1 downregulation in PDAC.

Suppression of the HBP Function Increases Pancreatic Cancer Cell Sensitivity to a Pan-RAS Inhibitor

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related death and the search for a resolutive therapy is still a challenge. Since KRAS is commonly mutated in PDAC and is one of the main drivers of PDAC progression, its inhibition should be a key strategy for treatment, especially considering the recent development of specific KRAS inhibitors. Nevertheless, the effects of KRAS inhibition can be increased through the co-inhibition of other nodes important for cancer development. One of them could be the hexosamine biosynthetic pathway (HBP), whose enhancement is considered fundamental for PDAC. Here, we demonstrate that PDAC cells expressing oncogenic KRAS, owing to an increase in the HBP flux, become strongly reliant on HBP for both proliferation and survival. In particular, upon treatment with two different compounds, 2-deoxyglucose and FR054, inhibiting both HBP and protein N-glycosylation, these cells undergo apoptosis significantly more than PDAC cells expressing wild-type KRAS. Importantly, we also show that the combined treatment between FR054 and the pan-RAS inhibitor BI-2852 has an additive negative effect on cell proliferation and survival by means of the suppression of both Akt activity and cyclin D1 expression. Thus, co-inhibition of HBP and oncogenic RAS may represent a novel therapy for PDAC patients.