Therapeutic potential of microbial modulation in pancreatic cancer

Microbiome Dysbiosis With Enterococcus Presence in the Upper Gastrointestinal Tract Is a Risk Factor for Mortality in Patients Undergoing Surgery for Pancreatic Cancer

BACKGROUND

Recent retrospective studies suggest a role for distinct microbiota in the perioperative morbidity and mortality of pancreatic head resections.

OBJECTIVE

We aimed to prospectively investigate the microbial colonization of critical operative sites of pancreatic head resections to identify microbial stratification factors for surgical and long-term oncologic outcomes.

METHODS

Prospective biomarker study applying 16S rRNA sequencing and microbial culturing to samples collected from various sites of the gastrointestinal tract and surgical sites of patients during pancreatic head resections at a German single high-volume pancreatic center.

RESULTS

A total of 101 patients were included {38 noncancer, 63 cancer patients [50 pancreatic ductal adenocarcinoma (PDAC) patients]} in the study. In a first data analysis series, 16S rRNA sequencing data were utilized from 96 patients to assess associations of microbiome profiles with clinical parameters and outcomes. In general, microbiome composition varied according to sampling site, cancer, age or preoperative endoscopic retrograde cholangiopancreatography (ERCP) intervention, notably for the bile microbiome. In the PDAC subcohort, the compositional variance of the bile or periampullary microbiome was significantly associated with postoperative complications such as intensive care unit admission; on a taxonomic level we observed Enterococcus spp. to be significantly more abundant in patients developing deep or organ-space surgical site infections (SSI). Elevated Enterococcus relative abundances in the upper gastrointestinal tract, in turn, were associated with 6 months mortality rates. In a second step, we focused on microbiological cultures collected from bile aspirates during surgery and investigated associations with perioperative complications and long-term survival. Notably, Enterococcus spp. were among the most prevalent pathobiont isolates observed in cancer patient bile specimens that were associated with severe SSIs, and thereby elevated mortality rates up to 24 months. Clinically relevant postoperative pancreatic fistulas or severe SSI were found as other major variables determining short-term mortality in this cancer patient cohort. In the context of adverse microbiological factors, a preoperative ERCP was also observed to segregate long-term survival, and it appeared to interact with the presence of Enterococcus spp. as highest mortality rates were observed in PDAC patients with both preoperative ERCP and presence of E. faecalis in bile aspirates.

CONCLUSIONS

The presence of Enterococcus spp. in bile ducts of PDAC patients undergoing pancreatic surgery represents a significant risk factor for perioperative infections and, thereby, elevated postoperative and long-term mortality. This finding supports previous data on the use of the antibiotic drug piperacillin-tazobactam as appropriate perioperative antibiotic prophylaxis for preventing adverse outcomes after pancreatoduodenectomy.

New onset diabetes predicts clinical outcomes in patients with pancreatic adenocarcinoma

Background

One percent of pancreatic adenocarcinoma (PDAC) patients are diagnosed with new onset diabetes (NOD) over the age of 50 years within 3 years. Therefore, NOD is a major factor for early diagnosis of PDAC. Research has focused on understanding the differences between NOD and type 2 diabetes, particularly in relation to PDAC. However, conflicting data exists regarding their impact on survival outcomes in PDAC patients. We performed this multi-center study to assess the prevalence and influence of NOD on clinical outcomes in patients with PDAC within a community-based hospital system.

Methods

We conducted a retrospective cohort study of 138 patients with biopsy-proven PDAC with localized/borderline disease (n=70), and metastatic disease (n=68) at three institutions from 2014 to 2021. NOD group consisted of pts diagnosed with diabetes [hemoglobin A1c (HbA1c) >6.5%] or pre-diabetes (HbA1c 5.7-6.4%) within the 3 years prior to PDAC diagnosis. Primary aim of the study was to determine the impact of NOD on clinical outcomes.

Results

A total of 138 patients were included in the study, from which 30 met the criteria for NOD. No significant differences were noted in the demographic and clinical characteristics comparing patients based on NOD history. Comparing survival outcomes, NOD group was associated with worse overall survival (OS) in both the metastatic cohort [n=68, progression-free survival (PFS) 4.6 vs. 7.1 months, P=0.07; OS 7.1 vs. 13.2 months, P=0.01) and the resected cohort (n=40, PFS 8.4 vs. 19.3 months, P=0.04; OS 24.5 vs. 42.3 months, P=0.04). In multivariate analysis, the impact of NOD remained significant for OS and PFS in the resected cohort. Identifying common features amongst the NOD group, we found the entire cohort had a significant reduction in individual body mass index (BMI) 1 year prior to the NOD diagnosis (P=0.006).

Conclusions

NOD is associated with worse survival outcomes in patients with metastatic and resected PDAC. Reduction of BMI prior to diagnosis of NOD, warrants further investigation to be incorporated into the PDAC screening paradigm.

Recent progress in nanomaterials for bacteria-related tumor therapy

Many studies suggest that tumor microbiome closely relates to the oncogenesis and anti-tumor responses in multiple cancer types (e.g., colorectal cancer (CRC), breast cancer, lung cancer and pancreatic cancer), thereby raising an emerging research area of bacteria-related tumor therapy. Nanomaterials have long been used for both cancer and bacterial infection treatment, holding great potential for bacteria-related tumor therapy. In this review, we summarized recent progress in nanomaterials for bacteria-related tumor therapy. We focus on the types and mechanisms of pathogenic bacteria in the development and promotion of cancers and emphasize how nanomaterials work. We also briefly discuss the design principles and challenges of nanomaterials for bacteria-related tumor therapy. We hope this review can provide some insights into this emerging and rapidly growing research area.

Gut epithelial Interleukin-17 receptor A signaling can modulate distant tumors growth through microbial regulation

Microbes influence cancer initiation, progression and therapy responsiveness. IL-17 signaling contributes to gut barrier immunity by regulating microbes but also drives tumor growth. A knowledge gap remains regarding the influence of enteric IL-17-IL-17RA signaling and their microbial regulation on the behavior of distant tumors. We demonstrate that gut dysbiosis induced by systemic or gut epithelial deletion of IL-17RA induces growth of pancreatic and brain tumors due to excessive development of Th17, primary source of IL-17 in human and mouse pancreatic ductal adenocarcinoma, as well as B cells that circulate to distant tumors. Microbial dependent IL-17 signaling increases DUOX2 signaling in tumor cells. Inefficacy of pharmacological inhibition of IL-17RA is overcome with targeted microbial ablation that blocks the compensatory loop. These findings demonstrate the complexities of IL-17-IL-17RA signaling in different compartments and the relevance for accounting for its homeostatic host defense function during cancer therapy.

Alarming correlation between multidrug-resistant bacteriobilia and morbidity after pancreatic surgery

BACKGROUND

Pancreatic surgery is characterized by high morbidity and mortality. Biliary colonization may affect clinical outcomes in these patients.

AIMS

This study aimed to verify whether bacteriobilia and multidrug resistance (MDR) detected during and after pancreatic surgery may have an impact on post-operative outcomes.

METHODS

Data from patients undergoing pancreatic surgery involving bile duct transection (2016-2022) in two high-volume centers were analyzed in relationship to overall morbidity, major morbidity and mortality after pancreato-duodenectomy (PD) or total pancreatectomy (TP). Simple and multivariable regressions were used.

RESULTS

227 patients submitted to PD (n=129) or TP (n=98) were included. Of them, 133 had preoperative biliary drainage (BD; 56.6%), mostly with the employment of endoscopic stents (91.7%). Bacteriobilia was detected in 111 patients (48.9%), and remarkably, observed in patients with BD (p=0.001). In addition, 25 MDR pathogens were identified (22.5%), with a significant prevalence in patients with BD. Multivariable regression analysis showed BD was strongly related to MDR isolation (odds ratio [OR]: 5.61; p=0.010). MDR isolation was the main factor linked to a higher number of major complications (OR: 2.75; p=0.041), including major infection complications (OR: 2.94; p=0.031).

CONCLUSIONS

Isolation of MDR from biliary swab during PD or TP significantly increases the risk of a worse post-operative outcome. Pre-operative precautions could improve patient safety.

Bioavailability and Antioxidant Activity of Rambutan (Nephelium lappaceum) Peel Polyphenols during in Vitro Simulated Gastrointestinal Digestion, Caco-2 Monolayer Cell Model Application, and Colonic Fermentation

The bioavailability of rambutan peel polyphenols (RPPs) was studied via in vitro simulated digestion, a Caco-2 monolayer cell model, and colonic fermentation. Total phenolic content of RPPs decreased with the progress of the simulated digestion. A total of 38 phenolic compounds were identified during the digestion and colonic fermentation, of which 12 new metabolites were found during colonic fermentation. The possible biotransformation pathways were inferred. Geraniin was transformed into corilagin, ellagic acid, and gallic acid during the digestion and colonic fermentation. Ellagic acid could be further transformed into urolithin under the action of intestinal microbiota. The transformation of ellagitannins could be beneficial to transport on Caco-2 monolayer cell. The antioxidant capacity of RPPs increased with the progress of gastrointestinal digestion. Furthermore, RPPs could increase the yield of short-chain fatty acids, decrease the pH value, promote the growth of beneficial bacteria, and inhibit the growth of pathogenic Escherichia coli/Shigella during colonic fermentation.

Bacterial and fungal characterization of pancreatic adenocarcinoma from Endoscopic Ultrasound-guided biopsies

Introduction

The tumor microbiome (TM) has been linked to pancreatic cancer prognosis. Specific microbes can confer tumor resistance to therapies. Early knowledge of the TM at time of diagnosis would be clinically relevant for precision therapy based on microbial composition. However, it is difficult to define the TM prior to surgical resection.

Methods

In this pilot feasibility study, patients underwent Endoscopic Ultrasound-Fine Needle Aspiration (EUS-FNA) biopsy of pancreatic adenocarcinoma. These samples were analyzed using 16S rRNA and internal transcribed spacer (ITS) sequencing for characterization of the tumor bacteria and fungi.

Result

After in silico decontamination and comparison to non-matched tumor, we were able to characterize the TM in biopsies, which was comparable to the TM from surgical specimens.

Discussion

EUS-FNA biopsy may represent a feasible modality to characterize the pancreatic TM prior to surgical resection with proper decontamination strategies and improvements in matched controls.

The role of gastric microecological dysbiosis in gastric carcinogenesis

Gastric cancer (GC) is the leading cause of cancer-related death worldwide, and reducing its mortality has become an urgent public health issue. Gastric microecological dysbiosis (including bacteria, fungi, viruses, acid suppressants, antibiotics, and surgery) can lead to gastric immune dysfunction or result in a decrease in dominant bacteria and an increase in the number and virulence of pathogenic microorganisms, which in turn promotes development of GC. This review analyzes the relationship between gastric microecological dysbiosis and GC, elucidates dynamic alterations of the microbiota in Correa's cascade, and identifies certain specific microorganisms as potential biomarkers of GC to aid in early screening and diagnosis. In addition, this paper presents the potential of gastric microbiota transplantation as a therapeutic target for gastric cancer, providing a new direction for future research in this field.

Intratumoural microbiota: from theory to clinical application

Cancer is a major cause of high morbidity and mortality worldwide. Several environmental, genetic and lifestyle factors are associated with the development of cancer in humans and result in suboptimal treatment. The human microbiota has been implicated in the pathophysiological process of cancer and has been used as a diagnostic, prognostic and risk assessment tool in cancer management. Notably, both extratumoural and intratumoural microbiota are important components of the tumor microenvironment, subtly influencing tumorigenesis, progression, treatment and prognosis. The potential oncogenic mechanisms of action of the intratumoural microbiota include induction of DNA damage, influence on cell signaling pathways and impairment of immune responses. Some naturally occurring or genetically engineered microorganisms can specifically accumulate and replicate in tumors and then initiate various anti-tumor programs, ultimately promoting the therapeutic effect of tumor microbiota and reducing the toxic and side effects of conventional tumor treatments, which may be conducive to the pursuit of accurate cancer treatment. In this review, we summarise evidence revealing the impact of the intratumoural microbiota on cancer occurrence and progress and potential therapeutic and diagnostic applications, which may be a promising novel strategy to inhibit tumor development and enhance therapeutic efficacy. Video Abstract.

Gender-specific changes of the gut microbiome correlate with tumor development in murine models of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with a dismal outcome. To improve understanding of sequential microbiome changes during PDAC development we analyzed mouse models of pancreatic carcinogenesis (KC mice recapitulating pre-invasive PanIN formation, as well as KPC mice recapitulating invasive PDAC) during early tumor development and subsequent tumor progression. Diversity and community composition were analyzed depending on genotype, age, and gender. Both mouse models demonstrated concordant abundance changes of several genera influenced by one or more of the investigated factors. Abundance was significantly impacted by gender, highlighting the need to further elucidate the impact of gender differences. The findings underline the importance of the microbiome in PDAC development and indicate that microbiological screening of patients at risk and targeting the microbiome in PDAC development may be feasible in future.

Microbiota in the Natural History of Pancreatic Cancer: From Predisposition to Therapy

Early microbiome insights came from gut microbes and their role among intestinal and extraintestinal disease. The latest evidence suggests that the microbiota is a true organ, capable of several interactions throughout the digestive system, attracting specific interest in the biliopancreatic district. Despite advances in diagnostics over the last few decades and improvements in the management of this disease, pancreatic cancer is still a common cause of cancer death. Microbiota can influence the development of precancerous disease predisposing to pancreatic cancer (PC). At the same time, neoplastic tissue shows specific characteristics in terms of diversity and phenotype, determining the short- and long-term prognosis. Considering the above information, a role for microbiota has also been hypothesized in the different phases of the PC approach, providing future revolutionary therapeutic insights. Microbiota-modulating therapies could open new issues in the therapeutic landscape. The aim of this narrative review is to assess the most updated evidence on microbiome in all the steps regarding pancreatic adenocarcinoma, from early development to response to antineoplastic therapy and long-term prognosis.

Review of the endocrine organ-like tumor hypothesis of cancer cachexia in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal types of solid tumors, associated with a high prevalence of cachexia (~80%). PDAC-derived cachexia (PDAC-CC) is a systemic disease involving the complex interplay between the tumor and multiple organs. The endocrine organ-like tumor (EOLT) hypothesis may explain the systemic crosstalk underlying the deleterious homeostatic shifts that occur in PDAC-CC. Several studies have reported a markedly heterogeneous collection of cachectic mediators, signaling mechanisms, and metabolic pathways, including exocrine pancreatic insufficiency, hormonal disturbance, pro-inflammatory cytokine storm, digestive and tumor-derived factors, and PDAC progression. The complexities of PDAC-CC necessitate a careful review of recent literature summarizing cachectic mediators, corresponding metabolic functions, and the collateral impacts on wasting organs. The EOLT hypothesis suggests that metabolites, genetic instability, and epigenetic changes (microRNAs) are involved in cachexia development. Both tumors and host tissues can secrete multiple cachectic factors (beyond only inflammatory mediators). Some regulatory molecules, metabolites, and microRNAs are tissue-specific, resulting in insufficient energy production to support tumor/cachexia development. Due to these complexities, changes in a single factor can trigger bi-directional feedback circuits that exacerbate PDAC and result in the development of irreversible cachexia. We provide an integrated review based on 267 papers and 20 clinical trials from PubMed and ClinicalTrials.gov database proposed under the EOLT hypothesis that may provide a fundamental understanding of cachexia development and response to current treatments.

Relationships among microbiota, gastric cancer, and immunotherapy

Currently, conventional neoadjuvant therapy or postoperative adjuvant therapy, such as chemotherapy and radiation therapy, can only bring limited survival benefits to gastric cancer (GC). Median survival after palliative chemotherapy is also low, at about 8-10 months. Immunotargeting is a new option for the treatment of GC, but has not been widely replicated. The highly immunosuppressed tumor microenvironment (TME) discounts the efficacy of immunotherapy for GC. Therefore, new strategies are needed to enhance the immune response of the TME. This paper reviewed the relationship between microorganisms and GC, potential links between microorganisms and immunotherapy and research of microorganisms combined immunotherapy.

Role of drug catabolism, modulation of oncogenic signaling and tumor microenvironment in microbe-mediated pancreatic cancer chemoresistance

Pancreatic ductal adenocarcinoma (PDAC) has one of the highest incidence/death ratios among all neoplasms due to its late diagnosis and dominant chemoresistance. Most PDAC patients present with an advanced disease characterized by a multifactorial, inherent and acquired resistance to current anticancer treatments. This remarkable chemoresistance has been ascribed to several PDAC features including the genetic landscape, metabolic alterations, and a heterogeneous tumor microenvironment that is characterized by dense fibrosis, and a cellular contexture including functionally distinct subclasses of cancer-associated fibroblasts, immune suppressive cells, but also a number of bacteria, shaping a specific tumor microbiome microenvironment. Thus, recent studies prompted the emergence of a new research avenue, by describing the role of the microbiome in gemcitabine resistance, while next-generation-sequencing analyses identified a specific microbiome in different tumors, including PDAC. Functionally, the contribution of these microbes to PDAC chemoresistance is only beginning to be explored. Here we provide an overview of the studies demonstrating that bacteria have the capacity to metabolically transform and hence inactivate anticancer drugs, as exemplified by the inhibition of the efficacy of 10 out of 30 chemotherapeutics by Escherichia coli. Moreover, a number of bacteria modulate specific oncogenic pathways, such as Fusobacterium nucleatum, affecting autophagy and apoptosis induction by 5-fluorouracil and oxaliplatin. We hypothesize that improved understanding of how chemoresistance is driven by bacteria could enhance the efficacy of current treatments, and discuss the potential of microbiome modulation and targeted therapeutic approaches as well as the need for more reliable models and biomarkers to translate the findings of preclinical/translational research to the clinical setting, and ultimately overcome PDAC chemoresistance, hence improving clinical outcome.

A ketogenic diet in combination with gemcitabine increases survival in pancreatic cancer KPC mice

Pancreatic ductal adenocarcinoma (PDAC) continues to be a major health problem. A ketogenic diet (KD), characterized by a very low carbohydrate and high fat composition, has gained attention for its anti-tumor potential. We evaluated the effect and mechanisms of feeding a strict KD alone or in combination with gemcitabine in the autochthonous LSL-Kras^G12D/+; LSL-Trp53 ^R172H/+; Pdx1-Cre (KPC) mouse model. For this purpose, both male and female pancreatic tumor-bearing KPC mice were allocated to a control diet (CD; %kcal: 70% carb, 14% protein, 16% fat), a KD (%kcal: 14% protein, 1% carb, 85% fat), a CD + gemcitabine (CG), or a KD + gemcitabine (KG) group. Mice fed a KD alone or in combination with gemcitabine showed significantly increased blood β-hydroxybutyrate levels compared to mice fed a CD or CG. KPC mice fed a KG had a significant increase in overall median survival compared to KPC mice fed a CD (increased overall median survival by 42%). Interestingly, when the data was disaggregated by sex, the effect of a KG was significant in female KPC mice (60% increase in median overall survival), but not in male KPC mice (28% increase in median overall survival). Mechanistically, the enhanced survival response to a KD combined with gemcitabine was multifactorial, including inhibition of ERK and AKT pathways, regulation of fatty acid metabolism and the modulation of the gut microbiota. In summary, a KD in combination with gemcitabine appears beneficial as a treatment strategy in PDAC in KPC mice, deserving further clinical evaluation.

The gut-liver axis: host microbiota interactions shape hepatocarcinogenesis

Although their etiologies vary, tumors share a common trait: the control of an oncogenic transcriptional program that is regulated by the interaction of the malignant cells with the stromal and immune cells in the tumor microenvironment (TME). The TME shows high phenotypic and functional heterogeneity that may be modulated by interactions with commensal microbes (the microbiota) both systemically and locally. Unlike host cells, the microbiota adapts after environmental perturbations, impacting host-microbe interactions. In the liver, the bidirectional relationship in the gut and its associated microbiota creates an interdependent environment. Therefore, the gut microbiota and its metabolites modulate liver gene expression directly and indirectly, causing an imbalance in the gut-liver axis, which may result in disease, including carcinogenesis.

pH-taxis drives aerobic bacteria in duodenum to migrate into the pancreas with tumors

As oral or intestinal bacteria have been found in pancreatic cystic fluid and tumors, understanding bacterial migration from the duodenum into the pancreas via hepato-pancreatic duct is critical. Mathematical models of migration of aerobic bacteria from the duodenum to the pancreas with tumors were developed. Additionally, the bacterial distributions under the pH gradient and those under flow were measured in double-layer flow based microfluidic device and T-shaped cylinders. Migration of aerobic bacteria from the duodenum into pancreas is counteracted by bile and pancreatic juice flow but facilitated by pH-taxis from acidic duodenum fluid toward more favorable slightly alkaline pH in pancreatic juice. Additionally, the reduced flow velocity in cancer patients, due to compressed pancreatic duct by solid tumor, facilitates migration. Moreover, measured distribution of GFP E. coli under the pH gradient in a microfluidic device validated pH-tactic behaviors. Furthermore, Pseudomonas fluorescens in hydrochloride solution, but not in bicarbonate solution, migrated upstream against bicarbonate flow of > 20 μm/s, with an advancement at approximately 50 μm/s.

Human Gut Microbiota in Health and Selected Cancers

The majority of the epithelial surfaces of our body, and the digestive tract, respiratory and urogenital systems, are colonized by a vast number of bacteria, archaea, fungi, protozoans, and viruses. These microbiota, particularly those of the intestines, play an important, beneficial role in digestion, metabolism, and the synthesis of vitamins. Their metabolites stimulate cytokine production by the human host, which are used against potential pathogens. The composition of the microbiota is influenced by several internal and external factors, including diet, age, disease, and lifestyle. Such changes, called dysbiosis, may be involved in the development of various conditions, such as metabolic diseases, including metabolic syndrome, type 2 diabetes mellitus, Hashimoto's thyroidis and Graves' disease; they can also play a role in nervous system disturbances, such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, and depression. An association has also been found between gut microbiota dysbiosis and cancer. Our health is closely associated with the state of our microbiota, and their homeostasis. The aim of this review is to describe the associations between human gut microbiota and cancer, and examine the potential role of gut microbiota in anticancer therapy.

Ketogenic Diets in Pancreatic Cancer and Associated Cachexia: Cellular Mechanisms and Clinical Perspectives

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive and extremely therapy-resistant cancer. It is estimated that up to 80% of PDAC patients present with cachexia, a multifactorial disorder characterized by the involuntary and ongoing wasting of skeletal muscle that affects therapeutic response and survival. During the last decade, there has been an increased interest in exploring dietary interventions to complement the treatment of PDAC and associated cachexia. Ketogenic diets (KDs) have gained attention for their anti-tumor potential. Characterized by a very low carbohydrate, moderate protein, and high fat composition, this diet mimics the metabolic changes that occur in fasting. Numerous studies report that a KD reduces tumor growth and can act as an adjuvant therapy in various cancers, including pancreatic cancer. However, research on the effect and mechanisms of action of KDs on PDAC-associated cachexia is limited. In this narrative review, we summarize the evidence of the impact of KDs in PDAC treatment and cachexia mitigation. Furthermore, we discuss key cellular mechanisms that explain KDs’ potential anti-tumor and anti-cachexia effects, focusing primarily on reprogramming of cell metabolism, epigenome, and the gut microbiome. Finally, we provide a perspective on future research needed to advance KDs into clinical use.

The Human Microbiomes in Pancreatic Cancer: Towards Evidence-Based Manipulation Strategies?

Recent pieces of evidence have emerged on the relevance of microorganisms in modulating responses to anticancer treatments and reshaping the tumor-immune microenvironment. On the one hand, many studies have addressed the role of the gut microbiota, providing interesting correlative findings with respect to etiopathogenesis and treatment responses. On the other hand, intra-tumoral bacteria are being recognized as intrinsic and essential components of the cancer microenvironment, able to promote a plethora of tumor-related aspects from cancer growth to resistance to chemotherapy. These elements will be probably more and more valuable in the coming years in early diagnosis and risk stratification. Furthermore, microbial-targeted intervention strategies may be used as adjuvants to current therapies to improve therapeutic responses and overall survival. This review focuses on new insights and therapeutic approaches that are dawning against pancreatic cancer: a neoplasm that arises in a central metabolic "hub" interfaced between the gut and the host.