Bacterial lipopolysaccharide as negative predictor of gemcitabine efficacy in advanced pancreatic cancer - translational results from the AIO-PK0104 Phase 3 study

Emerging clinical relevance of microbiome in cancer: promising biomarkers and therapeutic targets

The profound influence of microbiota in cancer initiation and progression has been under the spotlight for years, leading to numerous researches on cancer microbiome entering clinical evaluation. As promising biomarkers and therapeutic targets, the critical involvement of microbiota in cancer clinical practice has been increasingly appreciated. Here, recent progress in this field is reviewed. We describe the potential of tumor-associated microbiota as effective diagnostic and prognostic biomarkers, respectively. In addition, we highlight the relationship between microbiota and the therapeutic efficacy, toxicity, or side effects of commonly utilized treatments for cancer, including chemotherapy, radiotherapy, and immunotherapy. Given that microbial factors influence the cancer treatment outcome, we further summarize some dominating microbial interventions and discuss the hidden risks of these strategies. This review aims to provide an overview of the applications and advancements of microbes in cancer clinical relevance.

Microbiome and pancreatic cancer: time to think about chemotherapy

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer characterized by late diagnosis, rapid progression, and a high mortality rate. Its complex biology, characterized by a dense, stromal tumor environment with an immunosuppressive milieu, contributes to resistance against standard treatments like chemotherapy and radiation. This comprehensive review explores the dynamic role of the microbiome in modulating chemotherapy efficacy and outcomes in PDAC. It delves into the microbiome's impact on drug metabolism and resistance, and the interaction between microbial elements, drugs, and human biology. We also highlight the significance of specific bacterial species and microbial enzymes in influencing drug action and the immune response in the tumor microenvironment. Cutting-edge methodologies, including artificial intelligence, low-biomass microbiome analysis and patient-derived organoid models, are discussed, offering insights into the nuanced interactions between microbes and cancer cells. The potential of microbiome-based interventions as adjuncts to conventional PDAC treatments are discussed, paving the way for personalized therapy approaches. This review synthesizes recent research to provide an in-depth understanding of how the microbiome affects chemotherapy efficacy. It focuses on elucidating key mechanisms and identifying existing knowledge gaps. Addressing these gaps is crucial for enhancing personalized medicine and refining cancer treatment strategies, ultimately improving patient outcomes.

Screening of Exosome-Derived Proteins and Their Potential as Biomarkers in Diagnostic and Prognostic for Pancreatic Cancer

In the oncological area, pancreatic cancer is one of the most lethal diseases, with 5-year survival rising just 10% in high-development countries. This disease is genetically characterized by KRAS as a driven mutation followed by SMAD4, CDKN2, and TP53-associated mutations. In clinical aspects, pancreatic cancer presents unspecific clinical symptoms with the absence of screening and early plasmatic biomarker, being that CA19-9 is the unique plasmatic biomarker having specificity and sensitivity limitations. We analyzed the plasmatic exosome proteomic profile of 23 patients with pancreatic cancer and 10 healthy controls by using Nanoscale liquid chromatography coupled to tandem mass spectrometry (NanoLC-MS/MS). The pancreatic cancer patients were subdivided into IPMN and PDAC. Our findings show 33, 34, and 7 differentially expressed proteins when comparing the IPMN vs. control, PDAC-No treatment vs. control, and PDAC-No treatment vs. IPMN groups, highlighting proteins of the complement system and coagulation, such as C3, APOB, and SERPINA. Additionally, PDAC with no treatment showed 11 differentially expressed proteins when compared to Folfirinox neoadjuvant therapy or Gemcitabine adjuvant therapy. So here, we found plasmatic exosome-derived differentially expressed proteins among cancer patients (IPMN, PDAC) when comparing with healthy controls, which could represent alternative biomarkers for diagnostic and prognostic evaluation, supporting further scientific and clinical studies on pancreatic cancer.

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.

Cancer pharmacomicrobiomics: targeting microbiota to optimise cancer therapy outcomes

Despite the promising advances in novel cancer therapy such as immune checkpoint inhibitors (ICIs), limitations including therapeutic resistance and toxicity remain. In recent years, the relationship between gut microbiota and cancer has been extensively studied. Accumulating evidence reveals the role of microbiota in defining cancer therapeutic efficacy and toxicity. Unlike host genetics, microbiota can be easily modified via multiple strategies, including faecal microbiota transplantation (FMT), probiotics and antibiotics. Preclinical studies have identified the mechanisms on how microbes influence cancer treatment outcomes. Clinical trials have also demonstrated the potential of microbiota modulation in cancer treatments. Herein, we review the mechanistic insights of gut microbial interactions with chemotherapy and ICIs, particularly focusing on the interplay between gut bacteria and the pharmacokinetics (eg, metabolism, enzymatic degradation) or pharmacodynamics (eg, immunomodulation) of cancer treatment. The translational potential of basic findings in clinical settings is then explored, including using microbes as predictive biomarkers and microbial modulation by antibiotics, probiotics, prebiotics, dietary modulations and FMT. We further discuss the current limitations of gut microbiota modulation in patients with cancer and suggest essential directions for future study. In the era of personalised medicine, it is crucial to understand the microbiota and its interactions with cancer. Manipulating the gut microbiota to augment cancer therapeutic responses can provide new insights into cancer treatment.

Bacterial Lipopolysaccharide as a Negative Predictor of Adjuvant Gemcitabine Efficacy in Pancreatic Cancer

Adjuvant gemcitabine (aGC) is one standard of care after pancreatic ductal adenocarcinoma (PDAC) resection. No biomarker for its efficacy is established. As bacteria mediate gemcitabine resistance, we analyzed whether lipopolysaccharide (LPS) as surrogate for bacterial colonization is prognostic in PDAC patients treated with aGC or without aGC adjuvant gemcitabine. We detected LPS in 86 tumors from 376 patients, which defined a specific microbiome as revealed by 16 s-rRNA-sequencing. In the 230 aGC patients, LPS conferred worse disease-free survival (8.3 vs 13.7 months; hazard ratio = 1.75, 95% confidence interval = 1.22 to 2.49; log-rank P = .002) and overall survival (21.7 vs 28.5 months; hazard ratio = 1.80, 95% confidence interval = 1.23 to 2.57; log-rank P = .001) but not in the 146 naGC patients, which was confirmed in an independent validation cohort (n = 178). LPS may serve as a negative predictor for aGC efficacy in PDAC, which suggests a role for microbiome modification to overcome bacteria-mediated chemotherapy resistance.

Sequestration of Intestinal Acidic Toxins by Cationic Resin Attenuates Pancreatic Cancer Progression through Promoting Autophagic Flux for YAP Degradation

Simple Summary

Annually, more than 450,000 people are diagnosed with pancreatic cancer worldwide with over 430,000 mortalities. Pancreatic ductal carcinoma (PDAC) accounts for around 80% of pancreatic cancer cases with an extremely high mortality rate. Emerging research has demonstrated that gut dysbiosis is closely associated with pancreatic cancer, while the underlying mechanisms remain elusive. In this study, we found that elevated levels of endotoxin (LPS) and bile acids were associated with malignant progression in Kras-driven pancreatic cancer mice. Importantly, oral administration of cationic resins to sequestrate intestinal endotoxins and bile acids efficiently attenuated tumor progression. Thus, sequestration of intestinal acidic toxins by oral administration of cationic resins may have potential as an intervention strategy for pancreatic malignancy.

Abstract

Pancreatic cancer is driven by risk factors such as diabetes and chronic pancreatic injury, which are further associated with gut dysbiosis. Intestinal toxins such as bile acids and bacterial endotoxin (LPS), in excess and persistence, can provoke chronic inflammation and tumorigenesis. Of interest is that many intestinal toxins are negatively charged acidic components in essence, which prompted us to test whether oral administration of cationic resin can deplete intestinal toxins and ameliorate pancreatic cancer. Here, we found that increased plasma levels of endotoxin and bile acids in Pdx1-Cre: LSL-Kras^G12D/+ mice were associated with the transformation of the pancreatic ductal carcinoma (PDAC) state. Common bile-duct-ligation or LPS injection impeded autolysosomal flux, leading to Yap accumulation and malignant transformation. Conversely, oral administration of cholestyramine to sequestrate intestinal endotoxin and bile acids resumed autolysosomal flux for Yap degradation and attenuated metastatic incidence. Conversely, chloroquine treatment impaired autolysosomal flux and exacerbated malignance, showing jeopardization of p62/ Sqxtm1 turnover, leading to Yap accumulation, which is also consistent with overexpression of cystatin A (CSTA) in situ with pancreatic cancer cells and metastatic tumor. At cellular levels, chenodeoxycholic acid or LPS treatment activated the ligand–receptor-mediated AKT-mTOR pathway, resulting in autophagy-lysosomal stress for YAP accumulation and cellular dissemination. Thus, this work indicates a potential new strategy for intervention of pancreatic metastasis through sequestration of intestinal acidic toxins by oral administration of cationic resins.

Microbiota in Pancreatic Diseases: A Review of the Literature

The gut microbiota is a critical element in the balance between human health and disease. Its impairment, defined as dysbiosis, is associated with gastroenterological and systemic diseases. Pancreatic secretions are involved in the composition and changes of the gut microbiota, and the gut microbiota may colonize the pancreatic parenchyma and be associated with the occurrence of diseases. The gut microbiota and the pancreas influence each other, resulting in a "gut microbiota-pancreas axis". Moreover, the gut microbiota may be involved in pancreatic diseases, both through direct bacterial colonization and an indirect effect of small molecules and toxins derived from dysbiosis. Pancreatic diseases such as acute pancreatitis, chronic pancreatitis, autoimmune pancreatitis, and pancreatic cancer are common gastroenterological diseases associated with high morbidity and mortality. The involvement of the microbiota in pancreatic diseases is increasingly recognized. Therefore, modifying the intestinal bacterial flora could have important therapeutic implications on these pathologies. The aim of this study is to review the literature to evaluate the alterations of the gut microbiota in pancreatic diseases, and the role of the microbiota in the treatment of these diseases.

Gut-derived lipopolysaccharide remodels tumoral microenvironment and synergizes with PD-L1 checkpoint blockade via TLR4/MyD88/AKT/NF-κB pathway in pancreatic cancer

Lipopolysaccharide (LPS) as an important inflammatory mediator activates the innate/adaptive immune system. The existence of LPS in pancreatic ductal adenocarcinoma (PDAC) has been reported, however, its biological function in PDAC remains unclear. Here, we demonstrated that circulating and tumoral LPS was significantly increased by intestinal leakage in the orthotopic murine PDAC model, and LPS administration promoted T cell infiltration but exhaustion paradoxically in the subcutaneous murine PDAC model. By bioinformatic analysis, Toll-like receptor 4 (TLR4), LPS receptor, was further found to enrich in immune tolerance signaling in PDAC tissues. Then, a significant positive correlation was found between TLR4 and programmed death ligand-1 (PD-L1) in clinical PDAC tissues, as well as serum LPS and tumoral PD-L1. Meanwhile, LPS stimulation in vitro and in vivo obviously upregulated tumor PD-L1 expression, and effectively promoted cancer cells resistance to T cell cytotoxicity. Mechanistically, the activation of TLR4/MyD88/AKT/NF-κB cascade was found to participate in LPS mediated PD-L1 transcription via binding to its promoter regions, which was enhanced by crosstalk between NF-κB and AKT pathways. Finally, PD-L1 blockade could significantly reverse LPS-induced immune escape, and synergized with LPS treatment. Taken together, LPS can remodel tumor microenvironment, and synergize with PD-L1 blockade to suppress tumor growth, which may be a promising comprehensive strategy for PDAC.

Microbiome and cancer

The human microbiome constitutes a complex multikingdom community that symbiotically interacts with the host across multiple body sites. Host-microbiome interactions impact multiple physiological processes and a variety of multifactorial disease conditions. In the past decade, microbiome communities have been suggested to influence the development, progression, metastasis formation, and treatment response of multiple cancer types. While causal evidence of microbial impacts on cancer biology is only beginning to be unraveled, enhanced molecular understanding of such cancer-modulating interactions and impacts on cancer treatment are considered of major scientific importance and clinical relevance. In this review, we describe the molecular pathogenic mechanisms shared throughout microbial niches that contribute to the initiation and progression of cancer. We highlight advances, limitations, challenges, and prospects in understanding how the microbiome may causally impact cancer and its treatment responsiveness, and how microorganisms or their secreted bioactive metabolites may be potentially harnessed and targeted as precision cancer therapeutics.