Immunosuppression, immune escape, and immunotherapy in pancreatic cancer: focused on the tumor microenvironment

Enhancing pancreatic cancer immunotherapy: Leveraging localized delivery strategies through the use of implantable devices and scaffolds

Pancreatic cancer (PC) remains the predominant type of upper gastrointestinal tract cancer, associated with heightened morbidity and a survival rate below 12%. While immunotherapy has brought about transformative changes in the standards of care for most solid tumors, its application in PC is hindered by the ''cold tumor'' microenvironment, marked by the presence of immunosuppressive cells. Modest response rates in PC are attributed, in part to, the fibrotic stroma that obstructs the delivery of systemic immunotherapy. Furthermore, the occurrence of immune-related adverse events (iRAEs) often necessitates the use of sub-therapeutic doses or treatment discontinuation. In the pursuit of innovative approaches to enhance the effectiveness of immunotherapy for PC, implantable drug delivery devices and scaffolds emerge as promising strategies. These technologies offer the potential for sustained drug delivery directly to the tumor site, overcoming stromal barriers, immunosuppression, T cell exclusion, immunotherapy resistance, optimizing drug dosage, and mitigating systemic toxicity. This review offers a comprehensive exploration of pancreatic ductal adenocarcinoma (PDAC), the most common and aggressive form of PC, accompanied by a critical analysis of the challenges the microenvironment presents to the development of successful combinational immunotherapy approaches. Despite efforts, these approaches have thus far fallen short in enhancing treatment outcomes for PDAC. The review will subsequently delve into the imperative need for refining delivery strategies, providing an examination of past and ongoing studies in the field of localized immunotherapy for PDAC. Addressing these issues will lay the groundwork for the development of effective new therapies, thereby enhancing treatment response, patient survival, and overall quality of life for individuals diagnosed with PDAC.

Apolipoprotein E is a prognostic factor for pancreatic cancer and associates with immune infiltration

BACKGROUND

The expression level of apolipoprotein E (APOE) in pancreatic ductal adenocarcinoma (PDAC) and its effect on the prognosis of PDAC patients are not clear. The effect of APOE on the immune status of patients with PDAC has not been elucidated.

METHODS

We obtained pancreatic cancer data from the TCGA and GETx databases. Patients with PDAC who underwent pancreatic surgery at the Second Affiliated Hospital of Jiaxing University between 2012 and 2021 were included. Clinical pathological data were recorded, plasma APOE levels were measured, and tissue samples were collected. A tissue microarray was generated using the collected tissue samples. APOE and CD4 staining was performed to determine immunoreactive scores (IRSs). The expression of APOE in the plasma and tumour tissues of pancreatic cancer patients was analysed and compared. The correlations between plasma APOE levels, tissue APOE levels and clinicopathological characteristics were analysed. Survival prognosis was analysed using Kaplan-Meier survival analysis and Cox multivariate regression analysis. The correlations between APOE expression levels and immune biomarkers and immune cells were further analysed. Single-cell analysis of APOE distribution in various cells was performed on the TISCH website.

RESULTS

APOE was highly expressed in the tumour tissue of pancreatic cancer patients, and high plasma APOE levels were associated with poor prognosis. Females, patients with high-grade disease and patients with pancreatic head carcinoma had high plasma APOE levels. High APOE expression in tumour tissues was associated with good prognosis. Mononuclear macrophages in the pancreatic cancer microenvironment primarily expressed APOE. APOE levels positively correlated with immune biomarkers, such as CD8A, PDCD1, GZMA, CXCL10, and CXCL9, in the tumour microenvironment. APOE promoted CD4 + T cell or dendritic cell infiltration in the tumour microenvironment.

CONCLUSIONS

APOE may affect the occurrence and development of pancreatic cancer by regulating the infiltration of immune cells in the tumour microenvironment.

Frontiers and future of immunotherapy for pancreatic cancer: from molecular mechanisms to clinical application

Pancreatic cancer is a highly aggressive malignant tumor, that is becoming increasingly common in recent years. Despite advances in intensive treatment modalities including surgery, radiotherapy, biological therapy, and targeted therapy, the overall survival rate has not significantly improved in patients with pancreatic cancer. This may be attributed to the insidious onset, unknown pathophysiology, and poor prognosis of the disease. It is therefore essential to identify and develop more effective and safer treatments for pancreatic cancer. Tumor immunotherapy is the new and fourth pillar of anti-tumor therapy after surgery, radiotherapy, and chemotherapy. Significant progress has made in the use of immunotherapy for a wide variety of malignant tumors in recent years; a breakthrough has also been made in the treatment of pancreatic cancer. This review describes the advances in immune checkpoint inhibitors, cancer vaccines, adoptive cell therapy, oncolytic virus, and matrix-depletion therapies for the treatment of pancreatic cancer. At the same time, some new potential biomarkers and potential immunotherapy combinations for pancreatic cancer are discussed. The molecular mechanisms of various immunotherapies have also been elucidated, and their clinical applications have been highlighted. The current challenges associated with immunotherapy and proposed strategies that hold promise in overcoming these limitations have also been discussed, with the aim of offering new insights into immunotherapy for pancreatic cancer.

Tumor Microenvironment Modulates Invadopodia Activity of Non-Selected and Acid-Selected Pancreatic Cancer Cells and Its Sensitivity to Gemcitabine and C18-Gemcitabine

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease with high mortality due to early metastatic dissemination and high chemoresistance. All these factors are favored by its extracellular matrix (ECM)-rich microenvironment, which is also highly hypoxic and acidic. Gemcitabine (GEM) is still the first-line therapy in PDAC. However, it is quickly deaminated to its inactive metabolite. Several GEM prodrugs have emerged to improve its cytotoxicity. Here, we analyzed how the acidic/hypoxic tumor microenvironment (TME) affects the response of PDAC cell death and invadopodia-mediated ECM proteolysis to both GEM and its C18 prodrug.

METHODS

For this, two PDAC cell lines, PANC-1 and Mia PaCa-2 were adapted to pHe 6.6 or not for 1 month, grown as 3D organotypic cultures and exposed to either GEM or C18 in the presence and absence of acidosis and the hypoxia inducer, deferoxamine.

RESULTS

We found that C18 has higher cytotoxic and anti-invadopodia activity than GEM in all culture conditions and especially in acid and hypoxic environments.

CONCLUSIONS

We propose C18 as a more effective approach to conventional GEM in developing new therapeutic strategies overcoming PDAC chemoresistance.

Unveiling the immunosuppressive landscape of pancreatic ductal adenocarcinoma: implications for innovative immunotherapy strategies

Pancreatic cancer, particularly pancreatic ductal adenocarcinoma (PDAC), stands as the fourth leading cause of cancer-related deaths in the United States, marked by challenging treatment and dismal prognoses. As immunotherapy emerges as a promising avenue for mitigating PDAC's malignant progression, a comprehensive understanding of the tumor's immunosuppressive characteristics becomes imperative. This paper systematically delves into the intricate immunosuppressive network within PDAC, spotlighting the significant crosstalk between immunosuppressive cells and factors in the hypoxic acidic pancreatic tumor microenvironment. By elucidating these mechanisms, we aim to provide insights into potential immunotherapy strategies and treatment targets, laying the groundwork for future studies on PDAC immunosuppression. Recognizing the profound impact of immunosuppression on PDAC invasion and metastasis, this discussion aims to catalyze the development of more effective and targeted immunotherapies for PDAC patients.

Interplay of immune modulation, adaptive response and hormesis: Suggestive of threshold for clinical manifestation of effects of ionizing radiation at low doses?

The health impacts of low-dose ionizing radiation exposures have been a subject of debate over the last three to four decades. While there has been enough evidence of "no adverse observable" health effects at low doses and low dose rates, the hypothesis of "Linear No Threshold" continues to rule and govern the principles of radiation protection and the formulation of regulations and public policies. In adopting this conservative approach, the role of the biological processes underway in the human body is kept at abeyance. This review consolidates the available studies that discuss all related biological pathways and repair mechanisms that inhibit the progression of deleterious effects at low doses and low dose rates of ionizing radiation. It is pertinent that, taking cognizance of these processes, there is a need to have a relook at policies of radiation protection, which as of now are too stringent, leading to undue economic losses and negative public perception about radiation.

Intracellular Magnetic Hyperthermia Enables Concurrent Down-Regulation of CD47 and SIRPα To Potentiate Antitumor Immunity

Harnessing the potential of tumor-associated macrophages (TAMs) to engulf tumor cells offers promising avenues for cancer therapy. Targeting phagocytosis checkpoints, particularly the CD47-signal regulatory protein α (SIRPα) axis, is crucial for modulating TAM activity. However, single checkpoint inhibition has shown a limited efficacy. In this study, we demonstrate that ferrimagnetic vortex-domain iron oxide (FVIO) nanoring-mediated magnetic hyperthermia effectively suppresses the expression of CD47 protein on Hepa1-6 tumor cells and SIRPα receptor on macrophages, which disrupts CD47-SIRPα interaction. FVIO-mediated magnetic hyperthermia also induces immunogenic cell death and polarizes TAMs toward M1 phenotype. These changes collectively bolster the phagocytic ability of macrophages to eliminate tumor cells. Furthermore, FVIO-mediated magnetic hyperthermia concurrently escalates cytotoxic T lymphocyte levels and diminishes regulatory T cell levels. Our findings reveal that magnetic hyperthermia offers a novel approach for dual down-regulation of CD47 and SIRPα, reshaping the tumor microenvironment to stimulate immune responses, culminating in significant antitumor activity.

Involvement of the Gut Microbiome in the Local and Systemic Immune Response to Pancreatic Ductal Adenocarcinoma

The systemic and local immunosuppression exhibited by pancreatic ductal adenocarcinoma (PDAC) contributes significantly to its aggressive nature. There is a need for a greater understanding of the mechanisms behind this profound immune evasion, which makes it one of the most challenging malignancies to treat and thus one of the leading causes of cancer death worldwide. The gut microbiome is now thought to be the largest immune organ in the body and has been shown to play an important role in multiple immune-mediated diseases. By summarizing the current literature, this review examines the mechanisms by which the gut microbiome may modulate the immune response to PDAC. Evidence suggests that the gut microbiome can alter immune cell populations both in the peripheral blood and within the tumour itself in PDAC patients. In addition, evidence suggests that the gut microbiome influences the composition of the PDAC tumour microbiome, which exerts a local effect on PDAC tumour immune infiltration. Put together, this promotes the gut microbiome as a promising route for future therapies to improve immune responses in PDAC patients.

Repolarizing Tumor-Associated Macrophages and inducing immunogenic cell Death: A targeted liposomal strategy to boost cancer immunotherapy

Cancer immunotherapy has shown promise in treating various malignancies. However, the presence of an immunosuppressive tumor microenvironment (TME) triggered by M2 tumor-associated macrophages (TAMs) and the limited tumor cell antigenicity have hindered its broader application. To address these challenges, we developed DOX/R837@ManL, a liposome loaded with imiquimod (R837) and doxorubicin (DOX), modified with mannose-polyethylene glycol (Man-PEG). DOX/R837@ManL employed a mannose receptor (MRC1)-mediated targeting strategy, allowing it to accumulate selectively at M2 Tumor associated macrophages (TAMs) and tumor sites. R837, an immune adjuvant, promoted the conversion of immunosuppressive M2 TAMs into immunostimulatory M1 TAMs, and reshaped the immunosuppressive TME. Simultaneously, DOX release induced immunogenic cell death (ICD) in tumor cells and enhanced tumor cell antigenicity by promoting dendritic cells (DCs) maturation. Through targeted delivery, the synergistic action of R837 and DOX activated innate immunity and coordinated adaptive immunity, enhancing immunotherapy efficacy. In vivo experiments have demonstrated that DOX/R837@ManL effectively eliminated primary tumors and lung metastases, while also preventing tumor recurrence post-surgery. These findings highlighted the potential of DOX/R837@ManL as a promising strategy for cancer immunotherapy.

Targeting ONECUT3 blocks glycolytic metabolism and potentiates anti-PD-1 therapy in pancreatic cancer

BACKGROUND

Reprogramming glucose metabolism, also known as the Warburg effect (aerobic glycolysis), is a hallmark of cancers. Increased tumor glycolysis not only favors rapid cancer cell proliferation but reprograms the immune microenvironment to enable tumor progression. The transcriptional factor ONECUT3 plays key roles in the development of the liver and pancreas, however, limited is known about its oncogenic roles, particularly metabolic reprogramming.

METHODS

Immunohistochemistry and Western blotting are applied to determine the expression pattern of ONECUT3 and its clinical relevance in pancreatic ductal adenocarcinoma (PDAC). Knockdown and overexpression strategies are employed to determine the in vitro and in vivo functions of ONECUT3. Chromatin immunoprecipitation, luciferase reporter assay, and gene set enrichment analysis are used to decipher the molecular mechanisms.

RESULTS

The glycolytic metabolism is inversely associated with T-cell infiltration in PDAC. ONECUT3 is identified as a key regulator for PDAC glycolysis and CD8+ T-cell infiltration. Genetic silencing of ONECUT3 inhibits cell proliferation, promotes cell apoptosis, and reduces glycolytic metabolism as evidenced by glucose uptake, lactate production, and extracellular acidification rate. Opposite effects of ONECUT3 are observed in overexpression studies. ONECUT3 enhances aerobic glycolysis via transcriptional regulation of PDK1. Targeting ONECUT3 effectively suppresses tumor growth, increases CD8+ T-cell infiltration, and potentiates anti-PD-1 therapy in PDAC. Pharmacological inhibition of PDK1 also shows a synergistic effect with anti-PD-1 therapy. In clinical setting, ONECUT3 is closely associated with PDK1 expression and T-cell infiltration in PDAC and acts as an independent prognostic factor.

CONCLUSIONS

Our study reveals a previous unprecedented regulatory role of ONECUT3 in PDAC glycolysis and provides in vivo evidence that increased glycolysis is linked to an immunosuppressive microenvironment. Moreover, targeting ONECUT3-PDK1 axis may serve as a promising therapeutic approach for the treatment of PDAC.

Combination of mutations in genes controlling DNA repair and high mutational load plays a prognostic role in pancreatic ductal adenocarcinoma (PDAC): a retrospective real-life study in Sardinian population

BACKGROUND

Patients with pancreatic ductal adenocarcinoma (PDCA) carrying impaired mismatch repair mechanisms seem to have an outcome advantage under treatment with conventional chemotherapy, whereas the role for the tumor mutation burden on prognosis is controversial. In this study, we evaluated the prognostic role of the mutated genes involved in genome damage repair in a real-life series of PDAC patients in a hospital-based manner from the main Institution deputed to surgically treat such a disease in North Sardinia.

METHODS

A cohort of fifty-five consecutive PDAC patients with potentially resectable/border line resectable PDAC (stage IIB-III) or oligometastatic disease (stage IV) and tumor tissue availability underwent next-generation sequencing (NGS)-based analysis using a panel containing driver oncogenes and tumor suppressor genes as well as genes controlling DNA repair mechanisms.

RESULTS

Genes involved in the both genome damage repair (DR) and DNA mismatch repair (MMR) were found mutated in 17 (31%) and 15 (27%) cases, respectively. One fourth of PDAC cases (14/55; 25.5%) carried tumors presenting a combination of mutations in repair genes (DR and MMR) and the highest mutation load rates (MLR-H). After correction for confounders (surgery, adjuvant therapy, stage T, and metastasis), multivariate Cox regression analysis indicated that mutations in DR genes (HR = 3.0126, 95% CI 1.0707 to 8.4764, p = 0.0367) and the MLR (HR = 1.0018, 95%CI 1.0005 to 1.0032, p = 0.009) were significantly related to worse survival.

CONCLUSIONS

The combination of mutated repair genes and MLR-H, which is associated with a worse survival in our series of PDAC patients treated with conventional chemotherapy protocols, might become a predictive biomarker of response to immunotherapy in addition to its prognostic role in predicting survival.

Circular RNAs in pancreatic cancer progression

Pancreatic cancer (PC), typically diagnosed at relatively advanced stages with poor prognosis, is a dominant cause of cancer-related deaths worldwide. Accumulating evidence demonstrates that circular RNAs (circRNAs) are abnormally expressed in diverse tumors and affect tumorigenesis and progression. In this article, we examine the roles of circRNAs in regulation of PC progression. Additionally, circRNAs enriched in exosomes could be transferred among PC cells to modulate malignancy. Characterization of regulatory mechanisms involving circRNAs in general and PC specifically will enable earlier detection and potential development of therapeutic strategies.

Improving the prognosis of pancreatic cancer: insights from epidemiology, genomic alterations, and therapeutic challenges

Pancreatic cancer, notorious for its late diagnosis and aggressive progression, poses a substantial challenge owing to scarce treatment alternatives. This review endeavors to furnish a holistic insight into pancreatic cancer, encompassing its epidemiology, genomic characterization, risk factors, diagnosis, therapeutic strategies, and treatment resistance mechanisms. We delve into identifying risk factors, including genetic predisposition and environmental exposures, and explore recent research advancements in precursor lesions and molecular subtypes of pancreatic cancer. Additionally, we highlight the development and application of multi-omics approaches in pancreatic cancer research and discuss the latest combinations of pancreatic cancer biomarkers and their efficacy. We also dissect the primary mechanisms underlying treatment resistance in this malignancy, illustrating the latest therapeutic options and advancements in the field. Conclusively, we accentuate the urgent demand for more extensive research to enhance the prognosis for pancreatic cancer patients.

The role of KPNA2 as a monotonically changing differentially expressed gene in the diagnosis, risk stratification, and chemotherapy sensitivity of chronic hepatitis B-liver cirrhosis-hepatocellular carcinoma

PURPOSE

Chronic hepatitis B-liver cirrhosis-hepatocellular carcinoma (CLH), commonly called the "liver cancer trilogy", is a crucial evolutionary phase in the emergence of hepatocellular carcinoma (HCC) in China. Previous studies on early diagnostic biomarkers of HCC were limited to the end-stage of HCC and did not focus on the evolutionary process of CLH.

METHODS

11 monotonically changing differentially expressed genes (MCDEGs) highly correlated with CLH were screened through bioinformatic analysis and KPNA2 was identified for further research. The serum KPNA2 expression in different CLH states was detected by Enzyme linked immunosorbent assay (ELISA). A nomogram model was constructed using univariate and multivariate Cox regression methods.

RESULTS

The single-cell RNA-seq and bulk RNA-seq revealed that KPNA2 related to immune infiltration in HCC and may participate in cell cycle pathways in HCC. The serum KPNA2 expression was monotonically upregulated in CLH and was valuable for diagnosing different CLH states. Besides, chronic hepatitis B(CHB) patients, liver cirrhosis (LC) patients, and HCC patients were classified into subgroups with distinct serum KPNA2 expressions. Accordingly, patients with different serum KPNA2 expressions displayed various clinicopathological features. The AUC value of the nomogram model was 0.959 in predicting the likelihood of developing HCC in CHB patients or LC patients. Finally, we found that KPNA2 expression was negatively correlated with the IC50 of four chemotherapeutic drugs in HCC.

CONCLUSION

KPNA2 was a novel serum biomarker for diagnosing different CLH states, monitoring the dynamic evolution of CLH, and a new therapeutic target for intervening in the progression of CLH.

Seven chromatin regulators as immune cell infiltration characteristics, potential diagnostic biomarkers and drugs prediction in hepatocellular carcinoma

Treatment is challenging due to the heterogeneity of hepatocellular carcinoma (HCC). Chromatin regulators (CRs) are important in epigenetics and are closely associated with HCC. We obtained HCC-related expression data and relevant clinical data from The Cancer Genome Atlas (TCGA) databases. Then, we crossed the differentially expressed genes (DEGs), immune-related genes and CRs to obtain immune-related chromatin regulators differentially expressed genes (IRCR DEGs). Least absolute shrinkage and selection operator (LASSO) Cox regression analysis was performed to select the prognostic gene and construct a risk model for predicting prognosis in HCC, followed by a correlation analysis of risk scores with clinical characteristics. Finally, we also carried out immune microenvironment analysis and drug sensitivity analysis, the correlation between risk score and clinical characteristics was analyzed. In addition, we carried out immune microenvironment analysis and drug sensitivity analysis. Functional analysis suggested that IRCR DEGs was mainly enriched in chromatin-related biological processes. We identified and validated PPARGC1A, DUSP1, APOBEC3A, AIRE, HDAC11, HMGB2 and APOBEC3B as prognostic biomarkers for the risk model construction. The model was also related to immune cell infiltration, and the expression of CD48, CTLA4, HHLA2, TNFSF9 and TNFSF15 was higher in high-risk group. HCC patients in the high-risk group were more sensitive to Axitinib, Docetaxel, Erlotinib, and Metformin. In this study, we construct a prognostic model of immune-associated chromatin regulators, which provides new ideas and research directions for the accurate treatment of HCC.

PD-1 blockade combined with gemcitabine plus nab-paclitaxel is superior to chemotherapy alone in the management of unresectable stage III/IV pancreatic cancer: a retrospective real-world study

Background

Pancreatic cancer (PC) is widely recognized as one of the most malignant forms of cancer worldwide. Monotherapy with immune checkpoint inhibitors (ICI) has shown limited efficacy in treating this disease. There was controversy surrounding whether combining ICI with chemotherapy provided superior outcomes compared to chemotherapy alone.

Methods

In this study, patients diagnosed with unresectable stage III/IV pancreatic cancer (PC) were classified as receiving programmed cell death protein 1 (PD-1) blockade plus gemcitabine and nab-paclitaxel (AG regimen) (PD-1/chemo, n=27, 50.9%) or chemotherapy alone (chemo, n=26, 49.1%) arm. The primary study endpoints included progression-free survival (PFS) and overall survival (OS), with an additional assessment of treatment-related adverse events graded as three or higher. Chi-square (χ2) statistics were employed to analyze the clinical differences between the two groups, while Kaplan-Meier curves were used to assess the difference in PFS and OS. Statistical significance was defined as P-values less than 0.05 (P < 0.05).

Results

The median follow-up duration was 22 months (range 1-28 months). In the PD-1/chemo arm, the median PFS was eight months, whereas it was 3.5 months in the chemo arm (HR=0.459, 95% CI: 0.252-0.846, P=0.002). Furthermore, the median OS was 15 months in the PD-1/chemo arm and eight months in the chemo arm (HR=0.345, 95% CI: 0.183-0.653, P<0.001). Within the PD-1/chemo arm, 15 (55.6%) patients experienced grade 3 treatment-related adverse events, compared to 13 (50.0%) patients in the chemo arm.

Conclusions

PD-1 blockade combined with nab-paclitaxel plus gemcitabine demonstrated superior efficacy to chemotherapy alone for unresectable stage III/IV PC patients. Future studies were warranted to identify immunosensitive patient subgroups within the PC population, ultimately leading to the development of more efficacious therapeutic strategies.

Cellular senescence-related genes: predicting prognosis in hepatocellular carcinoma

Recent studies have shown that the high incidence and low cure rate of hepatocellular carcinoma (HCC) have not improved significantly. Surgery and liver transplantation are the mainstays of prolonging the survival of HCC patients. However, the surgical resection rate of HCC patients is very low, and even after radical surgical resection, the recurrence rate at 5 years postoperatively remains high and the prognosis is very poor, so more treatment options are urgently needed. Increasing evidence suggests that cellular senescence is not only related to cancer development but may also be one of its primary driving factors. We aimed to establish a prognostic signature of senescence-associated genes to predict the prognosis and therapeutic response of HCC patients. The aim of this study was to develop a risk model associated with cellular senescence and to search for potential strategies to treat HCC. We divided HCC patients into two clusters and identified differentially expressed genes (DEGs) between clusters. In this study, low-risk patients had a better prognosis, higher levels of immune cell infiltration, and better efficacy to fluorouracil, Paclitaxel and Cytarabine chemotherapy compared to high-risk patients. To further identify potential biomarkers for HCC, we further validated the expression levels of the four signature genes in HCC and neighbouring normal tissues by in vitro experiments. In conclusion, we identified and constructed a relevant prognostic signature, which performed well in predicting the survival and treatment response of HCC patients. This helps to differentiate between low-score and high-risk HCC, and the results may contribute to precise treatment protocols in clinical practice.

Transglutaminases are oncogenic biomarkers in human cancers and therapeutic targeting of TGM2 blocks chemoresistance and macrophage infiltration in pancreatic cancer

PURPOSE

Transglutaminases (TGs) are multifunctional enzymes exhibiting transglutaminase crosslinking, as well as atypical GTPase/ATPase and kinase activities. Here, we used an integrated comprehensive analysis to assess the genomic, transcriptomic and immunological landscapes of TGs across cancers.

METHODS

Gene expression and immune cell infiltration patterns across cancers were obtained from The Cancer Genome Atlas (TCGA) database and Gene Set Enrichment Analysis (GSEA) datasets. Western blotting, immunofluorescence staining, enzyme-linked immunosorbent assays, and orthotopic xenograft models were used to validate our database-derived results.

RESULTS

We found that the overall expression of TGs (designated as the TG score) is significantly upregulated in multiple cancers and related to a worse patient survival. The expression of TG family members can be regulated through multiple mechanisms at the genetic, epigenetic and transcriptional levels. The expression of transcription factors crucial for epithelial-to-mesenchymal transition (EMT) is commonly correlated with the TG score in many cancer types. Importantly, TGM2 expression displays a close connection with chemoresistance to a wide range of chemotherapeutic drugs. We found that TGM2 expression, F13A1 expression and the overall TG score were positively correlated with the infiltration of immune cells in all cancer types tested. Functional and clinical verification revealed that a higher TGM2 expression is linked with a worse patient survival, an increased IC50 value of gemcitabine, and a higher abundance of tumor-infiltrating macrophages in pancreatic cancer. Mechanistically, we found that increased C-C motif chemokine ligand 2 (CCL2) release mediated by TGM2 contributes to macrophage infiltration into the tumor microenvironment.

CONCLUSIONS

Our results reveal the relevance and molecular networks of TG genes in human cancers and highlight the importance of TGM2 in pancreatic cancer, which may provide promising directions for immunotherapy and for addressing chemoresistance.

A nanodrug simultaneously inhibits pancreatic stellate cell activation and regulatory T cell infiltration to promote the immunotherapy of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense extracellular matrix flooded with immune suppressive cells, resulting in extremely poor clinical response to immunotherapy. It has been revealed that the activation of pancreatic stellate cells (PSCs) makes considerable contributions to the immunological "cold" tumor microenvironment (TME). Herein, we developed a polyamino acid-based nanodrug incorporating the PSC activation inhibitor calcipotriol and anti-CXCL12 siRNA. The nanodrug was easily prepared with a small particle size and is capable of penetrating pancreatic tumors to inactivate PSCs and downregulate CXCL12. The in vivo results of orthotopic pancreatic tumor treatment demonstrated that codelivery of calcipotriol and anti-CXCL12 siRNA remodeled the PDAC TME with reduced extracellular matrix and decreased immunosuppressive T cells. Eventually, the infiltration of cytotoxic T cells was increased, thereby acting with immune checkpoint blockade (ICB) therapy for immunologically "cold" pancreatic tumors. In the present study, we propose a promising paradigm to improve the immunotherapy outcome of PDAC using nanodrugs that synchronously inhibit PSC activation and regulatory T-cell infiltration. STATEMENT OF SIGNIFICANCE: Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense extracellular matrix (ECM) that impedes the tumor infiltration of therapeutic agents and cytotoxic T lymphocytes, resulting in a poor clinical response to immunotherapy. In the present study, we proposed a promising approach for enhanced immunotherapy of pancreatic cancer. Specifically, a nanodrug incorporating calcipotriol and anti-CXCL12 siRNA was synthesized to synchronously inactivate matrix-producing pancreatic stellate cells and suppress the infiltration of regulatory T cells. The reduced ECM removed the pathological barrier, preventing nanodrug penetration and effector T-cell infiltration, leading to a conversion of the immunosuppressive "cold" microenvironment to a "hot" microenvironment, which eventually boosted the immunotherapy of anti-PD-1 antibodies in pancreatic cancer.

Multifunctional GQDs for receptor targeting, drug delivery, and bioimaging in pancreatic cancer

Pancreatic cancer is a devastating disease with a low survival rate and limited treatment options. Graphene quantum dots (GQDs) have recently become popular as a promising platform for cancer diagnosis and treatment due to their exceptional physicochemical properties, such as biocompatibility, stability, and fluorescence. This review discusses the potential of multifunctional GQDs as a platform for receptor targeting, drug delivery, and bioimaging in pancreatic cancer. The current studies emphasized the ability of GQDs to selectively target pancreatic cancer cells by overexpressing binding receptors on the cell surface. Additionally, this review discussed the uses of GQDs as drug delivery vehicles for the controlled and targeted release of therapeutics for pancreatic cancer cells. Finally, the potential of GQDs as imaging agents for pancreatic cancer detection and monitoring has been discussed. Overall, multifunctional GQDs showed great promise as a versatile platform for the diagnosis and treatment of pancreatic cancer. Further investigation of multifunctional GQDs in terms of their potential and optimization in the context of pancreatic cancer therapy is needed.

Advances in Immunotherapeutics in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) accounts for up to 95% of all pancreatic cancer cases and is the seventh-leading cause of cancer death. Poor prognosis is a result of late presentation, a lack of screening tests and the fact some patients develop resistance to chemotherapy and radiotherapy. Novel therapies like immunotherapeutics have been of recent interest in pancreatic cancer. However, this field remains in its infancy with much to unravel. Immunotherapy and other targeted therapies have yet to yield significant progress in treating PDAC, primarily due to our limited understanding of the disease immune mechanisms and its intricate interactions with the tumour microenvironment (TME). In this review we provide an overview of current novel immunotherapies which have been studied in the field of pancreatic cancer. We discuss their mechanisms, evidence available in pancreatic cancer as well as the limitations of such therapies. We showcase the potential role of combining novel therapies in PDAC, postulate their potential clinical implications and the hurdles associated with their use in PDAC. Therapies discussed with include programmed death checkpoint inhibitors, Cytotoxic T-lymphocyte-associated protein 4, Chimeric Antigen Receptor-T cell therapy, oncolytic viral therapy and vaccine therapies including KRAS vaccines, Telomerase vaccines, Gastrin Vaccines, Survivin-targeting vaccines, Heat-shock protein (HSP) peptide complex-based vaccines, MUC-1 targeting vaccines, Listeria based vaccines and Dendritic cell-based vaccines.

CD74 Promotes a Pro-Inflammatory Tumor Microenvironment by Inducing S100A8 and S100A9 Secretion in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive form of pancreatic cancer with a poor prognosis and low survival rates. The prognostic and predictive biomarkers of PDAC are still largely unknown. The receptor CD74 was recently identified as a regulator of oncogenic properties in various cancers. However, the precise molecular mechanism of CD74 action in PDAC remains little understood. We investigated the role of CD74 by silencing CD74 in the pancreatic cancer cell line Capan-1. CD74 knockdown led to reductions in cell proliferation, migration, and invasion and increased apoptosis. Moreover, silencing CD74 resulted in the decreased expression and secretion of S100A8 and S100A9. An indirect co-culture of fibroblasts and tumor cells revealed that fibroblasts exposed to conditioned media from CD74 knockdown cells exhibited a reduced expression of inflammatory cytokines, suggesting a role of CD74 in influencing cytokine secretion in the tumor microenvironment. Overall, our study provides valuable insights into the critical role of CD74 in regulating the oncogenic properties of pancreatic cancer cells and its influence on the expression and secretion of S100A8 and S100A9. Taken together, these findings indicate CD74 as a potential diagnostic biomarker and therapeutic target for pancreatic cancer.

Oncolytic adenoviruses and the treatment of pancreatic cancer: a review of clinical trials

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) remains a common and difficult cancer to treat. Surgical resection and chemotherapy are standard of care and clinical outcomes remain poor. Oncolytic adenoviruses are a unique approach to the treatment of this challenging cancer, aiming to overcome the features of this disease that pose the key obstacles to standard therapies. This paper provides a detailed review of the clinical trials of conditionally-replicative adenoviruses in pancreatic cancer to date, with a brief summary of the past preclinical literature and future prospects of this therapy.

METHODS

MEDLINE, Embase, and clinicaltrials.gov were searched from inception to December 23rd 2022 for clinical trials of conditionally-replicative adenoviruses used in patients with pancreatic ductal adenocarcinoma. Primary features for review included patient demographics, treatment protocol including dose and administration route, adverse events, patient responses and survival rates.

RESULTS

The six published clinical trials suggest that objective clinical responses can be achieved with a tolerable level of side effects, even at high viral doses. The more clinically adaptable intravenous route of administration also appears to be as well tolerated as the more challenging intratumoural injections.

CONCLUSION

Published clinical trials provide data of the safety and some signs of oncolytic activity of conditionally-replicative adenoviruses in patients with pancreatic cancer. Importantly, on the latest trials, the easier intravenous route of administration seems to be well tolerated and safe, providing the opportunity for further clinical evaluation. It is hoped that the ongoing clinical trials will yield more promising results of this therapeutic approach against a currently intractable disease.

Molecular and metabolic regulation of immunosuppression in metastatic pancreatic ductal adenocarcinoma

Immunosuppression is a hallmark of pancreatic ductal adenocarcinoma (PDAC), contributing to early metastasis and poor patient survival. Compared to the localized tumors, current standard-of-care therapies have failed to improve the survival of patients with metastatic PDAC, that necessecitates exploration of novel therapeutic approaches. While immunotherapies such as immune checkpoint blockade (ICB) and therapeutic vaccines have emerged as promising treatment modalities in certain cancers, limited responses have been achieved in PDAC. Therefore, specific mechanisms regulating the poor response to immunotherapy must be explored. The immunosuppressive microenvironment driven by oncogenic mutations, tumor secretome, non-coding RNAs, and tumor microbiome persists throughout PDAC progression, allowing neoplastic cells to grow locally and metastasize distantly. The metastatic cells escaping the host immune surveillance are unique in molecular, immunological, and metabolic characteristics. Following chemokine and exosomal guidance, these cells metastasize to the organ-specific pre-metastatic niches (PMNs) constituted by local resident cells, stromal fibroblasts, and suppressive immune cells, such as the metastasis-associated macrophages, neutrophils, and myeloid-derived suppressor cells. The metastatic immune microenvironment differs from primary tumors in stromal and immune cell composition, functionality, and metabolism. Thus far, multiple molecular and metabolic pathways, distinct from primary tumors, have been identified that dampen immune effector functions, confounding the immunotherapy response in metastatic PDAC. This review describes major immunoregulatory pathways that contribute to the metastatic progression and limit immunotherapy outcomes in PDAC. Overall, we highlight the therapeutic vulnerabilities attributable to immunosuppressive factors and discuss whether targeting these molecular and immunological "hot spots" could improve the outcomes of PDAC immunotherapies.

Characterization of 3D heterocellular spheroids of pancreatic ductal adenocarcinoma for the study of cell interactions in the tumor immune microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies nowadays. The available chemo- and immunotherapies are often ineffective in treating PDAC due to its immunosuppressive and highly desmoplastic tumor immune microenvironment (TIME), which is hardly reproduced in the existing preclinical models. The PDAC TIME results from a peculiar spatial organization between different cell types. For this reason, developing new human models recapitulating the tissue organization and cell heterogeneity of PDAC is highly desirable. We developed human 3D heterocellular tumor spheroids of PDAC formed by cancer cells, endothelial cells, pancreatic stellate cells (PSC), and monocytes. As a control, we formed spheroids using immortalized epithelial pancreatic ductal cells (non-cancerous spheroids) with cellular heterogeneity similar to the tumor spheroids. Normal spheroids containing endothelial cells formed a complex 3D endothelial network significantly compromised in tumor spheroids. Monocyte/macrophages within the 4-culture tumor spheroids were characterized by a higher expression of CD163, CD206, PD-L1, and CD40 than those in the non-cancerous spheroids suggesting their differentiation towards an immunosuppressive phenotype. The heterocellular tumor spheroids presented a hypoxic core populated with PSC and monocytes/macrophages. The 4-culture tumor spheroids were characterized by spatial proximity of PSC and monocytes to the endothelial cells and a cytokine signature with increased concentrations of CXCL10, CCL2, and IL-6, which have been observed in PDAC patients and associated with poor survival. Further, 4-culture tumor spheroids decreased the concentrations of T-cell chemoattracting cytokines, i.e., CCL4, CCL5, and CXCL9, when compared with the non-cancerous spheroids, revealing a critical immunosuppressive feature of the different types of cells forming the tumor spheroids. Our results showed that the 4-culture tumor spheroids better resembled some critical features of patients' PDAC TIME than monoculture tumor spheroids. Using the proposed human 3D spheroid model for therapy testing at the preclinical stage may reveal pitfalls of chemo- and immuno-therapies to help the development of better anti-tumor therapies.

Pancreatic Ductal Adenocarcinoma and Immune Checkpoint Inhibitors: The Gray Curtain of Immunotherapy and Spikes of Lights

Pancreatic ductal adenocarcinoma (PDAC) is a dismal disease with a poor 5-year overall survival rate (~10%). The revolution of immunotherapy in clinical oncology has not substantially changed clinical outcome for patients with PDAC. Despite outstanding efforts, neither immune checkpoint inhibitors (ICIs) alone, nor in combination with chemotherapy or targeted therapies have shown encouraging results. This failure mirrors the lack of knowledge about the real key players of immune system senescence and the complexity of the tumor microenvironment in PDAC. However, some hope can be derived from PARP-inhibitor combinations, vaccines, and CAR-T-cells therapy. In this review, we comprehensively summarize the latest updates about the use of ICIs in PDAC, focusing on clinical evidence and ongoing studies highlighting explanations for the failure of immunotherapy and possible solutions.

The ceramide synthase (CERS/LASS) family: Functions involved in cancer progression

INTRODUCTION

Ceramide synthases (CERSes) are also known longevity assurance (LASS) genes. CERSes play important roles in the regulation of cancer progression. The CERS family is expressed in a variety of human tumours and is involved in tumorigenesis. They are closely associated with the progression of liver, breast, cervical, ovarian, colorectal, head and neck squamous cell, gastric, lung, prostate, oesophageal, pancreatic and blood cancers. CERSes play diverse and important roles in the regulation of cell survival, proliferation, apoptosis, migration, invasion, and drug resistance. The differential expression of CERSes in tumour and nontumour cells and survival analysis of cancer patients suggest that some CERSes could be used as potential prognostic markers. They are also important potential targets for cancer therapy.

METHODS

In this review, we summarize the available evidence on the inhibitory or promotive roles of CERSes in the progression of many cancers. Furthermore, we summarize the identified upstream and downstream molecular mechanisms that may regulate the function of CERSes in cancer settings.

Dysfunctional epigenetic protein-coding gene-related signature is associated with the prognosis of pancreatic cancer based on histone modification and transcriptome analysis

Emerging evidence suggests that epigenetic alterations are responsible for the oncogenesis and progression of cancer. However, the role of epigenetic reprogramming in pancreatic cancer is still not clear. In this study, we used the limma R package to identify differentially expressed protein-coding genes (PCGs) between pancreatic cancer tissues and normal control tissues. The cell-type identification by the estimating relative subsets of RNA transcripts (CIBERSORT) package was used to quantify relative cell fractions in tumors. Prognostic molecular clusters were constructed using ConsensusClusterPlus analysis. Furthermore, the least absolute shrinkage and selection operator and stepAIC methods were used to construct a risk model. We identified 2351 differentially expressed PCGs between pancreatic cancer and normal control tissues in The cancer genome atlas dataset. Combined with histone modification data, we identified 363 epigenetic PCGs (epi-PCGs) and 19,010 non-epi-PCGs. Based on the epi-PCGs, we constructed three molecular clusters characterized by different expression levels of chemokines and immune checkpoint genes and distinct abundances of various immune cells. Furthermore, we generated a 9-gene model based on dysfunctional epi-PCGs. Additionally, we found that patients with high risk scores showed poorer prognoses than patients with low risk scores (p < 0.0001). Further analysis showed that the risk score was significantly related to survival and was an independent risk factor for pancreatic cancer patients. In conclusion, we constructed a 9-gene prognostic risk model based on epi-PCGs that might serve as an effective classifier to predict overall survival and the response to immunotherapy in pancreatic cancer patients.