Gut microbiome influences efficacy of PD-1-based immunotherapy against epithelial tumors

Eravacycline improves the efficacy of anti-PD1 immunotherapy via AP1/CCL5 mediated M1 macrophage polarization in melanoma

Screening approved library is a promising and safe strategy to overcome the limitation of low response rate and drug resistance in immunotherapy. Accumulating evidence showed that the application of antibiotics has been considered to reduce the effectiveness of anti-PD1 immunotherapy in tumor treatment, however, in this study, an antibiotic drug (Eravacycline, ERV) was identified to improve the efficacy of anti-PD1 immunotherapy in melanoma through screening approved library. Administration of ERV significantly attenuated melanoma cells growth as well as directly or indirectly benefited M1 macrophage polarization. Meanwhile, ERV treatment significantly induced cellular autophagy via damage of mitochondria, leading to up-regulation of ROS production, subsequently, raised CCL5 secretion through elevation AP1 binding to CCL5 promoter via p38 or JNK1/2 activation. Knockdown of Ccl5 expression attenuated ERV triggered M1 macrophage polarization in melanoma cells. Clinical analysis revealed a positive association between high expression of CCL5 and improved prognosis as well as a favorable anti-PD1 therapy in melanoma patients. As expected, application of ERV improved the efficacy of anti-PD1. Overall, our results approved that ERV enhances the efficacy of anti-PD1 immunotherapy in melanoma by promoting the polarization of M1 macrophages, which provided novel therapeutic strategy for improving the effectiveness of melanoma anti-PD1 immunotherapy.

Understanding and overcoming resistance to immunotherapy in genitourinary cancers

The introduction of novel immunotherapies has significantly transformed the treatment landscape of genitourinary (GU) cancers, even becoming the standard of care in some settings. One such type of immunotherapy, immune checkpoint inhibitors (ICIs) like nivolumab, ipilimumab, pembrolizumab, and atezolizumab play a pivotal role by disturbing signaling pathways that limit the immune system's ability to fight tumor cells. Despite the profound impact of these treatments, not all tumors are responsive. Recent research efforts have been focused on understanding how cancer cells manage to evade the immune response and identifying the possible mechanisms behind resistance to immunotherapy. In response, ICIs are being combined with other treatments to reduce resistance and attack cancer cells through multiple cellular pathways. Additionally, novel, targeted strategies are currently being investigated to develop innovative methods of overcoming resistance and treatment failure. This article presents a comprehensive overview of the mechanisms of immunotherapy resistance in GU cancers as currently described in the literature. It explores studies that have identified genetic markers, cytokines, and proteins that may predict resistance or response to immunotherapy. Additionally, we review current efforts to overcome this resistance, which include combination ICIs and sequential therapies, novel insights into the host immune profile, and new targeted therapies. Various approaches that combine immunotherapy with chemotherapy, targeted therapy, vaccines, and radiation have been studied in an effort to more effectively overcome resistance to immunotherapy. While each of these combination therapies has shown some efficacy in clinical trials, a deeper understanding of the immune system's role underscores the potential of novel targeted therapies as a particularly promising area of current research. Currently, several targeted agents are in development, along with the identification of key immune mediators involved in immunotherapy resistance. Further research is necessary to identify predictors of response.

Immunotherapy resistance in solid tumors: mechanisms and potential solutions

While the emergence of immunotherapies has fundamentally altered the management of solid tumors, cancers exploit many complex biological mechanisms that result in resistance to these agents. These encompass a broad range of cellular activities - from modification of traditional paradigms of immunity via antigen presentation and immunoregulation to metabolic modifications and manipulation of the tumor microenvironment. Intervening on these intricate processes may provide clinical benefit in patients with solid tumors by overcoming resistance to immunotherapies, which is why it has become an area of tremendous research interest with practice-changing implications. This review details the major ways cancers avoid both natural immunity and immunotherapies through primary (innate) and secondary (acquired) mechanisms of resistance, and it considers available and emerging therapeutic approaches to overcoming immunotherapy resistance.

The critical role of tumor microbiome in cancer immunotherapy

In recent years, the microbiome has shown an integral role in cancer immunotherapy and has become a prominent and widely studied topic. A full understanding of the interactions between the tumor microbiome and various immunotherapies offers opportunities for immunotherapy of cancer. This review scrutinizes the composition of the tumor microbiome, the mechanism of microbial immune regulation, the influence of tumor microorganisms on tumor metastasis, and the interaction between tumor microorganisms and immunotherapy. In addition, this review also summarizes the challenges and opportunities of immunotherapy through tumor microbes, as well as the prospects and directions for future related research. In conclusion, the potential of microbial immunotherapy to enhance treatment outcomes for cancer patients should not be underestimated. Through this review, it is hoped that more research on tumor microbial immunotherapy will be done to better solve the treatment problems of cancer patients.

The RIG-I-like receptor signaling pathway triggered by Staphylococcus aureus promotes breast cancer metastasis

Host microbes are increasingly recognized as key components in various types of cancer, although their exact impact remains unclear. This study investigated the functional significance of Staphylococcus aureus (S. aureus) in breast cancer tumorigenesis and progression. We found that S. aureus invasion resulted in a compromised DNA damage response process, as evidenced by the absence of G1-phase arrest and apoptosis in breast cells in the background of double strand breaks production and the activation of the ataxia-telangiectasia mutated (ATM)-p53 signaling pathway. The high-throughput mRNA sequencing, bioinformatics analysis and pharmacological studies revealed that S. aureus facilitates breast cell metastasis through the innate immune pathway, particularly in cancer cells. During metastasis, S. aureus initially induced the expression of RIG-I-like receptors (RIG-I in normal breast cells, RIG-I and MDA5 in breast cancer cells), which in turn activated NF-κB p65 expression. We further showed that NF-κB p65 activated the CCL5-CCR5 pathway, contributing to breast cell metastasis. Our study provides novel evidence that the innate immune system, triggered by bacterial infection, plays a role in bacterial-driven cancer metastasis.

The oral-gut microbiome axis in health and disease

The human body hosts trillions of microorganisms throughout many diverse habitats with different physico-chemical characteristics. Among them, the oral cavity and the gut harbour some of the most dense and diverse microbial communities. Although these two sites are physiologically distinct, they are directly connected and can influence each other in several ways. For example, oral microorganisms can reach and colonize the gastrointestinal tract, particularly in the context of gut dysbiosis. However, the mechanisms of colonization and the role that the oral microbiome plays in causing or exacerbating diseases in other organs have not yet been fully elucidated. Here, we describe recent advances in our understanding of how the oral and intestinal microbiota interplay in relation to their impact on human health and disease.

The progress on the relationship between gut microbiota and immune checkpoint blockade in tumors

Immune checkpoint blockade (ICB) has emerged as a promising immunotherapeutic approach for the treatment of various tumors. However, the efficacy of this therapy is limited in a subset of patients, and it is important to develop strategies to enhance immune responses. Studies have demonstrated a critical role of gut microbiota in regulating the therapeutic response to ICB. Gut microbiota composition, diversity, and function are mediated by metabolites, such as short-chain fatty acids and secondary bile acids, that interact with host immune cells through specific receptors. In addition, gut bacteria may translocate to the tumor site and stimulate antitumor immune responses. Therefore, maintaining a healthy gut microbiota composition, for instance through avoiding the use of antibiotics or probiotic interventions, can be an effective approach to optimize ICB therapy. This review summarizes the current understanding of the microbiota-immunity interactions in the context of ICB therapy, and discusses potential clinical implications of these findings.

Changes in the gut microbial profile during long-term androgen deprivation therapy for prostate cancer

BACKGROUND

Recent studies have highlighted the association between androgen deprivation therapy (ADT) and the gut microbiota in prostate cancer. However, the impact of long-term ADT remains to be explored.

METHODS

To examine changes in the gut microbial profile from short-term (a median of 7 months), and middle-term (a median of 18 months) to long-term ADT (>33 months), 16S rRNA data from 56 fecal samples were reanalyzed. Additionally, a two-sample Mendelian randomization was employed to investigate the relationships between particular microbial signatures and prostate cancer as well as testosterone levels.

RESULTS

In contrast to the short- and middle-term ADT groups, the long-term ADT group had significant changes in alpha and beta diversity. In particular, the relative abundance of genera such as Catenibacterium and Holdemanella decreased in the long-term ADT group, whereas the opportunistic bacterium (Erysipelatoclostridium) and Ruminococcus gnavus showed increased abundance over ADT time. Moreover, a two-sample Mendelian randomization analysis revealed the negative associations between genetically predicated genera Coprobacter, Ruminococcaceae UCG002/011, and Defluviitaleacea-UCG-011, and testosterone levels.

CONCLUSIONS

In conclusion, long-term ADT use in prostate cancer patients was associated with detrimental changes in gut microbiota, including an increase in genera related to testosterone synthesis and opportunistic bacteria. These changes may be related to disease progression and side effects of long-term ADT while further longitudinal studies are required to prove this relationship.

Factors of faecal microbiota transplantation applied to cancer management

The homeostasis of the microbiota is essential for human health. In particular, the gut microbiota plays a critical role in the regulation of the immune system. Thus, faecal microbiota transplantation (FMT), a technology that has rapidly developed in the last decade, has specifically been utilised for the treatment of intestinal inflammation and has recently been found to be able to treat tumours in combination with immunotherapy. FMT has become a breakthrough in enhancing the response rate to immunotherapy in cancer patients by altering the composition of the patient's gut microbiota. This review discusses the mechanisms of faecal microorganism effects on tumour development, drug treatment efficacy, and adverse effects and describes the recent clinical research trials on FMT. Moreover, the factors influencing the efficacy and safety of FMT are described. We summarise the possibilities of faecal transplantation in the treatment of tumours and its complications and propose directions to explore the development of FMT.

Longitudinal analysis of the gut microbiota during anti-PD-1 therapy reveals stable microbial features of response in melanoma patients

Immune checkpoint inhibitors (ICIs) improve outcomes in advanced melanoma, but many patients are refractory or experience relapse. The gut microbiota modulates antitumor responses. However, inconsistent baseline predictors point to heterogeneity in responses and inadequacy of cross-sectional data. We followed patients with unresectable melanoma from baseline and during anti-PD-1 therapy, collecting fecal and blood samples that were surveyed for changes in the gut microbiota and immune markers. Varying patient responses were linked to different gut microbiota dynamics during ICI treatment. We select complete responders by their stable microbiota functions and validate them using multiple external cohorts and experimentally. We identify major histocompatibility complex class I (MHC class I)-restricted peptides derived from flagellin-related genes of Lachnospiraceae (FLach) as structural homologs of tumor-associated antigens, detect FLach-reactive CD8+ T cells in complete responders before ICI therapy, and demonstrate that FLach peptides improve antitumor immunity. These findings highlight the prognostic value of microbial functions and therapeutic potential of tumor-mimicking microbial peptides.

Associations of the gut microbiome with outcomes in cervical and endometrial cancer patients treated with pembrolizumab: Insights from the phase II PRIMMO trial

BACKGROUND

The phase II PRIMMO trial investigated a pembrolizumab-based regimen in patients with recurrent and/or metastatic cervical (CC) or endometrial (EC) carcinoma who had at least one prior line of systemic therapy. Here, exploratory studies of the gut microbiome (GM) are presented.

METHODS

The microbial composition of 77 longitudinal fecal samples obtained from 35 patients (CC, n = 15; EC, n = 20) was characterized using 16S rRNA gene sequencing. Analyses included assessment of alpha (Shannon index) and beta diversity (weighted UniFrac), unbiased hierarchical clustering, and linear discriminant analysis effect size. Correlative studies with demographics, disease characteristics, safety, efficacy, and immune monitoring data were performed.

RESULTS

Significant enrichment in multiple bacterial taxa was associated with the occurrence or resistance to severe treatment-related adverse events (overall or gastrointestinal toxicity specifically). Consistent differences in GM taxonomic composition before pembrolizumab initiation were observed between patients with favorable efficacy (e.g., enriched with Blautia genus) and those with poor efficacy (e.g., enriched with Enterobacteriaceae family and its higher-level taxa up to the phylum level, as well as Clostridium genus and its Clostridiaceae family). Two naturally occurring GM clusters with distinct bacterial compositions were identified. These clusters showed a more than four-fold differential risk for death (hazard ratio, 4.4 [95 % confidence interval, 1.9 to 10.3], P < 0.001) and were associated with interesting (but non-significant) trends in peripheral immune monitoring data.

CONCLUSION

Although exploratory, this study offers initial insights into the intricate interplay between the GM and clinical outcomes in patients with CC and EC treated with a pembrolizumab-based regimen.

TRIAL REGISTRATION

ClinicalTrials.gov (identifier NCT03192059) and EudraCT Registry (number 2016-001569-97).

The danger theory of immunity revisited

The danger theory of immunity, introduced by Polly Matzinger in 1994, posits that tissue stress, damage or infection has a decisive role in determining immune responses. Since then, a growing body of evidence has supported the idea that the capacity to elicit cognate immune responses (immunogenicity) relies on the combination of antigenicity (the ability to be recognized by T cell receptors or antibodies) and adjuvanticity (additional signals arising owing to tissue damage). Here, we discuss the molecular foundations of the danger theory while focusing on immunologically relevant damage-associated molecular patterns, microorganism-associated molecular patterns, and neuroendocrine stress-associated immunomodulatory molecules, as well as on their receptors. We critically evaluate patient-relevant evidence, examining how cancer cells and pathogenic viruses suppress damage-associated molecular patterns to evade immune recognition, how intestinal dysbiosis can reduce immunostimulatory microorganism-associated molecular patterns and compromise immune responses, and which hereditary immune defects support the validity of the danger theory. Furthermore, we incorporate the danger hypothesis into a close-to-fail-safe hierarchy of immunological tolerance mechanisms that also involve the clonal deletion and inactivation of immune cells.

Acetate-producing bacterium Paenibacillus odorifer hampers lung cancer growth in lower respiratory tract: an in vitro study

Lung cancer accounts for the large majority of cancer incidence and mortality worldwide for decades. The dysbiotic microbiome and its metabolite secretions in the gut have been regarded as the dominant biological factors in oncogenesis, development, and progression, adding probiotic components of which have come to be potential therapeutic regimes. However, there still exists little knowledge about whether probiotic microorganisms in lower airways inhibit lung cancer by lung microenvironment remodulation. In this study, we performed bioinformatics analysis from previous sequencing data and specific microbiome databases to identify the potent protective microbes in lower airways, followed by bacterial cultivation and morphological verifications in vitro. We found that Paenibacillus odorifer was correlated closely with the anti-tumorous by-product acetic acid in lower respiratory tract. Additionally, the enrichment of this microorganism in the health, rather than in lung neoplasms from public data sets, further confirmed its protective activity in preserving pulmonary homeostasis. Colony cultivation of this strain and targeted metabolite analysis indicated that Paenibacillus odorifer proliferation was weakened at 37°C but lasted longer than it did at the optimal temperature. And performing as a candidate origin of acetic acid, this strain was liable to inhibit the growth of lung cancer cells in time- and dose-dependent approaches which was validated by colony formation assays. These results suggested that Paenibacillus odorifer functions as a candidate probiotic in lower airways to restrict lung cancer cell growth by releasing protective molecules, indicating a potential preventive microbial strategy.IMPORTANCEVarious types of microorganisms in lower respiratory tracts protect local homeostasis against oncogenesis. Although extensive efforts engaged in gut microbiome-mediated pulmonary carcinogenesis, emerging evidence suggested the crucial role of microbial metabolites from respiratory tracts in modulating carcinogenesis-related host inflammation and DNA damage in lung cancer, which was still not fully understood in lower respiratory tract microbes and its metabolite-mediated microecological environment homeostasis in preventing or alleviating lung cancer. In this study, we analyzed the lower respiratory tract microbiome and SCFAs expression among different lung segments from the same participants, further identifying that Paenibacillus odorifer was correlated closely with anti-tumorous by-product, acetate acid in lower respiratory tract by multi-omics analysis. And previous experiments showed this strain could inhibit the growth of lung cancer cells in vitro. These findings indicated that Paenibacillus odorifer in lower respiratory tracts might perform as a candidate probiotic against lung carcinogenesis by releasing protective factor acetate, which further presented a promising diagnostic and interventional approach in clinical settings of lung cancer.

Insights of gut-liver axis in hepatic diseases: Mechanisms, clinical implications, and therapeutic potentials

With the rising prevalence of chronic liver diseases worldwide, there exists a need to diversify our artillery to incorporate a plethora of diagnostic and therapeutic methods to combat this disease. Currently, the most common causes of liver disease are non-alcoholic fatty liver disease, hepatitis, and alcoholic liver disease. Some of these chronic diseases have the potential to transform into hepatocellular carcinoma with advancing fibrosis. In this review, we analyse the relationship between the gut and liver and their significance in liver disease. This two-way relationship has interesting effects on each other in liver diseases. The gut microbiota, through its metabolites, influences the metabolism in numerous ways. Careful manipulation of its composition can lead to the discovery of numerous therapeutic potentials that can be applied in the treatment of various liver diseases. Numerous cohort studies with a pan-omics approach are required to understand the association between the gut microbiome and hepatic disease progression through which we can identify effective ways to deal with this issue.

Diagnosing and engineering gut microbiomes

The microbes, nutrients and toxins that we are exposed to can have a profound effect on the composition and function of the gut microbiome. Thousands of peer-reviewed publications link microbiome composition and function to health from the moment of birth, right through to centenarians, generating a tantalizing glimpse of what might be possible if we could intervene rationally. Nevertheless, there remain relatively few real-world examples where successful microbiome engineering leads to beneficial health effects. Here we aim to provide a framework for the progress needed to turn gut microbiome engineering from a trial-and-error approach to a rational medical intervention. The workflow starts with truly understanding and accurately diagnosing the problems that we are trying to fix, before moving on to developing technologies that can achieve the desired changes.

Navigating the complex relationship between human gut microbiota and breast cancer: Physiopathological, prognostic and therapeutic implications

The human body represents the habitat of trillions of symbiotic microorganisms, collectively known as human microbiota, approximately half of which residing in the gut. The development of next-generation sequencing techniques has boosted the profiling of human microbiota in recent years. A growing body of evidence seems to support a strict relationship between the disruption of the mutualistic relationship between the microbiota and the host (i.e., dysbiosis) and the development of several diseases, including breast malignancies. Breast cancer still represents the most frequent cause of cancer-related death in women. Its complex relationship with gut microbiota is the object of a growing body of evidence. In fact, the interaction with the host immune system and a direct impact of gut microbiota on estrogen, lipid and polyphenols metabolism, seem to potentially affect breast tumor development, progression and response to treatments. In this review, in an attempt to help oncologists navigating this rapidly-evolving research field, we provide an essential overview on the taxonomy, main analytical techniques and terminology most commonly adopted. We discuss what is currently known regarding the interaction between gut microbiota and breast cancer and potential efforts to harness this complex interplay for therapeutic purposes, and revise main ongoing studies. We also briefly provide an overview on breast cancer intratumoral microbiota and its potential role beyond gut microbiota.

AI in microbiome-related healthcare

Artificial intelligence (AI) has the potential to transform clinical practice and healthcare. Following impressive advancements in fields such as computer vision and medical imaging, AI is poised to drive changes in microbiome-based healthcare while facing challenges specific to the field. This review describes the state-of-the-art use of AI in microbiome-related healthcare. It points out limitations across topics such as data handling, AI modelling and safeguarding patient privacy. Furthermore, we indicate how these current shortcomings could be overcome in the future and discuss the influence and opportunities of increasingly complex data on microbiome-based healthcare.

Microbiome dynamics in immune checkpoint blockade

Immune checkpoint blockade (ICB) is one of the leading immunotherapies, although a variable extent of resistance has been observed among patients and across cancer types. Among the efforts underway to overcome this challenge, the microbiome has emerged as a factor affecting the responsiveness and efficacy of ICB. Active research, facilitated by advances in sequencing techniques, is assessing the predominant influence of the intestinal microbiome, as well as the effects of the presence of an intratumoral microbiome. In this review, we describe recent findings from clinical trials, observational studies of human patients, and animal studies on the impact of the microbiome on the efficacy of ICB, highlighting the role of the intestinal and tumor microbiomes and the contribution of methodological advances in their study.

Fecal, duodenal, and tumor microbiota composition of esophageal carcinoma patients, a longitudinal prospective cohort

BACKGROUND

The microbiome has been associated with chemotherapy and immune checkpoint inhibitor efficacy. How this pertains to resectable esophageal carcinoma is unknown. Our aim was to identify microbial signatures in resectable esophageal carcinoma associated with response to neoadjuvant chemoradiotherapy with or without an immune checkpoint inhibitor.

METHODS

From 2 prospectively collected esophageal carcinoma cohorts (n = 172 in total) treated with neoadjuvant chemoradiotherapy alone (n = 132) or a combination of neoadjuvant chemoradiotherapy and an immune checkpoint inhibitor (n = 40), fecal samples were available at baseline, during treatment, and presurgery. Additionally, in the immune checkpoint inhibitor-treated patients, tumor and duodenal snap frozen biopsies were collected over time. Fecal, tumor, and duodenal DNA were extracted for 16S ribosomal RNA sequencing. Associations were investigated between microbiome composition pathological complete response and progression-free survival (PFS).

RESULTS

There was a statistically significant shift in the microbiota profile of the fecal, tumor, and duodenal microbiota over time. In the total cohort, patients with a pathological complete response had a stable fecal alpha diversity, while the diversity of poor responders decreased during treatment (P = .036). Presurgery, lower alpha diversity (<4.12) was related to worse PFS (log-rank P = .025). Baseline tumor biopsies of patients with short PFS had more Fusobacterium. A low baseline duodenal alpha diversity (<3.96) was associated with worse PFS (log-rank P = .012).

CONCLUSIONS

Lower intestinal alpha diversity was associated with worse response and survival of esophageal carcinoma patients. In tumor biopsies, Fusobacterium was more abundant in patients with poor PFS. After further mechanistic validation, these findings may aid in response prediction and the design of novel microbiome modulating treatments for esophageal carcinoma patients.

The Rational Engineered Bacteria Based Biohybrid Living System for Tumor Therapy

Living therapy based on bacterial cells has gained increasing attention for their applications in tumor treatments. Bacterial cells can naturally target to tumor sites and active the innate immunological responses. The intrinsic advantages of bacteria attribute to the development of biohybrid living carriers for targeting delivery toward hypoxic environments. The rationally engineered bacterial cells integrate various functions to enhance the tumor therapy and reduce toxic side effects. In this review, the antitumor effects of bacteria and their application are discussed as living therapeutic agents across multiple antitumor platforms. The various kinds of bacteria used for cancer therapy are first introduced and demonstrated the mechanism of antitumor effects as well as the immunological effects. Additionally, this study focused on the genetically modified bacteria for the production of antitumor agents as living delivery system to treat cancer. The combination of living bacterial cells with functional nanomaterials is then discussed in the cancer treatments. In brief, the rational design of living therapy based on bacterial cells highlighted a rapid development in tumor therapy and pointed out the potentials in clinical applications.

Older adults with cancer and common comorbidities-challenges and opportunities in improving their cancer treatment outcomes

The older American population is rapidly increasing, and millions of older adults will be cancer survivors with comorbidities. This population faces specific challenges regarding treatment and has unique clinical needs. Recognizing this need, the National Cancer Institute, in collaboration with the National Institute on Aging, hosted a webinar series, entitled Cancer, Aging, and Comorbidities. This commentary provides a reflection of 5 thematic areas covered by the webinar series, which was focused on improving cancer treatment for older adults with cancer and comorbidities: 1) the impact of comorbidities on treatment tolerability and patient outcomes; 2) the impact of comorbidities on cancer clinical trial design; 3) the development of wearable devices in measuring comorbidities in cancer treatment; 4) the effects of nutrition and the microbiome on cancer therapy; and 5) the role of senescence and senotherapy in age-related diseases. Advances have been made in these areas, however, many gaps and challenges exist and are discussed in this commentary. To improve cancer survivorship in older populations with comorbidities, aging and comorbidities must be jointly considered and incorporated across the spectrum of cancer research. This includes more basic research of the mechanisms linking comorbidities and cancer development and treatment response, building critical resources and infrastructure (eg, preclinical models and patient samples), conducting clinical trials focused on the older population, integrating geriatric assessment into cancer treatment, and incorporating novel technologies, such as wearable devices, into clinical trials and cancer care.

Current status and prospect of gut and oral microbiome in pancreatic cancer: Clinical and translational perspectives

Pancreatic cancer is a highly lethal malignancy, and its diagnosis and treatment continue to pose significant challenges. Despite advancements in surgical and comprehensive treatment methods, the five-year survival rate remains below 12 %. With the rapid development of microbiome science, the gut and oral microbiota, which are readily accessible and can be sampled non-invasively, have emerged as a novel area of interest in pancreatic cancer research. Dysbiosis in these microbial communities can induce persistent inflammatory responses and affect the host's immune system, promoting cancer development and impacting the efficacy of treatments like chemotherapy and immunotherapy. This review provides an up-to-date overview of the roles of both gut and oral microbiota in the onset, progression, diagnosis, and treatment of pancreatic cancer. It analyzes the potential of utilizing these microbiomes as biomarkers and therapeutic targets from a clinical application perspective. Furthermore, it discusses future research directions aimed at harnessing these insights to advance the diagnosis and treatment strategies for pancreatic cancer. By focusing on the microbiome's role in clinical and translational medicine, this review offers insights into improving pancreatic cancer diagnosis and treatment outcomes.

Design of probiotic delivery systems and their therapeutic effects on targeted tissues

The microbiota at different sites in the body is closely related to disease. The intake of probiotics is an effective strategy to alleviate diseases and be adjuvant in their treatment. However, probiotics may suffer from harsh environments and colonization resistance, making it difficult to maintain a sufficient number of live probiotics to reach the target sites and exert their original probiotic effects. Encapsulation of probiotics is an effective strategy. Therefore, probiotic delivery systems, as effective methods, have been continuously developed and innovated to ensure that probiotics are effectively delivered to the targeted site. In this review, initially, the design of probiotic delivery systems is reviewed from four aspects: probiotic characteristics, processing technologies, cell-derived wall materials, and interactions between wall materials. Subsequently, the review focuses on the effects of probiotic delivery systems that target four main microbial colonization sites: the oral cavity, skin, intestine, and vagina, as well as disease sites such as tumors. Finally, this review also discusses the safety concerns of probiotic delivery systems in the treatment of disease and the challenges and limitations of implementing this method in clinical studies. It is necessary to conduct more clinical studies to evaluate the effectiveness of different probiotic delivery systems in the treatment of diseases.

An Explainable Graph Neural Framework to Identify Cancer-Associated Intratumoral Microbial Communities

Microbes are extensively present among various cancer tissues and play critical roles in carcinogenesis and treatment responses. However, the underlying relationships between intratumoral microbes and tumors remain poorly understood. Here, a MIcrobial Cancer-association Analysis using a Heterogeneous graph transformer (MICAH) to identify intratumoral cancer-associated microbial communities is presented. MICAH integrates metabolic and phylogenetic relationships among microbes into a heterogeneous graph representation. It uses a graph transformer to holistically capture relationships between intratumoral microbes and cancer tissues, which improves the explainability of the associations between identified microbial communities and cancers. MICAH is applied to intratumoral bacterial data across 5 cancer types and 5 fungi datasets, and its generalizability and reproducibility are demonstrated. After experimentally testing a representative observation using a mouse model of tumor-microbe-immune interactions, a result consistent with MICAH's identified relationship is observed. Source tracking analysis reveals that the primary known contributor to a cancer-associated microbial community is the organs affected by the type of cancer. Overall, this graph neural network framework refines the number of microbes that can be used for follow-up experimental validation from thousands to tens, thereby helping to accelerate the understanding of the relationship between tumors and intratumoral microbiomes.

Increased abundance of Firmicutes and depletion of Bacteroidota predicts poor outcome in chronic lymphocytic leukemia

Evidence indicates that there are significant alterations in gut microbiota diversity and composition in patients with hematological malignancies. The present study investigated the oral and intestinal microbiome in patients with chronic lymphocytic leukemia (CLL) (n=81) and age-matched healthy volunteers (HVs; n=21) using 16S ribosomal RNA next-generation sequencing. Changes in both oral and gut microbiome structures were identified, with a high abundance of Proteobacteria and depletion of Bacteroidetes in CLL as compared to HVs. Oral and stool samples of patients with CLL revealed a significant change in the abundance of short-chain fatty acid-producing genera in comparison with HVs. Furthermore, the relative abundance of oral and intestine Bacteroidetes was significantly decreased in patients with CLL with negative prognostic features, including unmutated immunoglobulin heavy chain gene (IGHV). Notably, an increased abundance of gut Firmicutes was found to be associated with high expression of CD38. Finally, the present study suggested the log Firmicutes/Bacteroidota ratio as a novel intestinal microbiome signature associated with a shorter time to first treatment in individuals with CLL. The findings indicate that oral and gut microbial diversity in CLL might point to the inflammatory-related modulation of the clinical course of the disease.

Exploring the gut microbiome and head and neck cancer interplay

The gut microbiome, a complex community of microorganisms residing in the gastrointestinal tract, plays a crucial role in maintaining human health and influencing disease outcomes. Recent advancements in sequencing technologies have revealed the intricate relationship between gut microbiota and various health conditions. This review explores the impact of gut microbiome dysbiosis on immune function, chronic inflammation, and cancer progression. Dysbiosis, characterized by an imbalance in microbial populations, can lead to immune dysfunction, creating a pro-inflammatory environment conducive to tumorigenesis. Gut microbiome metabolites, such as short-chain fatty acids and bile acids, also play a significant role in modulating these processes. The interplay between these factors contributes to the development and progression of HNC. Furthermore, this review highlights the potential of therapeutic interventions targeting the gut microbiome, including probiotics, prebiotics, and dietary modifications, to restore microbial balance and mitigate cancer risk. Understanding the mechanisms by which the gut microbiome influences HNC can provide valuable insights into novel preventive and therapeutic strategies. Future research should focus on elucidating the specific microbial taxa and metabolites involved in HNC, as well as the impact of lifestyle factors such as diet, alcohol consumption, and oral hygiene on the gut microbiome. By leveraging the growing knowledge of the gut microbiome, it may be possible to develop personalized approaches to cancer prevention and treatment, ultimately improving patient outcomes.

Fecal microbial transplants as investigative tools in cancer

The gut microbiome plays a critical role in the development, progression, and treatment of cancer. As interest in microbiome-immune-cancer interactions expands, the prevalence of fecal microbial transplant (FMT) models has increased proportionally. However, current literature does not provide adequate details or consistent approaches to allow for necessary rigor and experimental reproducibility. In this review, we evaluate key studies using FMT to investigate the relationship between the gut microbiome and various types of cancer. In addition, we will discuss the common pitfalls of these experiments and methods for improved standardization and validation as the field uses FMT with greater frequency. Finally, this review focuses on the impacts of the gut and extraintestinal microbes, prebiotics, probiotics, and postbiotics in cancer risk and response to therapy across a variety of tumor types.NEW & NOTEWORTHY The microbiome impacts the onset, progression, and therapy response of certain types of cancer. Fecal microbial transplants (FMTs) are an increasingly prevalent tool to test these mechanisms that require standardization by the field.

Effects of gut microbiota on immune checkpoint inhibitors in multi-cancer and as microbial biomarkers for predicting therapeutic response

BACKGROUND

Gut bacteria are related to immune checkpoint inhibitors (ICIs). However, there is inconsistency in ICI-associated species, while the role of non-bacterial microbes in immunotherapy remains elusive. Here, we evaluated the association of trans-kingdom microbes with ICIs by multi-cohort multi-cancer analyses.

METHODS

We retrieved fecal metagenomes from 1,359 ICI recipients with four different cancers (metastatic melanoma [MM], non-small cell lung carcinoma [NSCLC], renal cell cancer [RCC], and hepatocellular carcinoma) from 12 published datasets. Microbiota composition was analyzed using the Wilcoxon rank test. The performance of microbial biomarkers in predicting ICI response was assessed by random forest. Key responder-associated microbes were functionally examined in vitro and in mice.

FINDINGS

Trans-kingdom gut microbiota (bacteria, eukaryotes, viruses, and archaea) was significantly different between ICI responders and non-responders in multi-cancer. Bacteria (Faecalibacterium prausnitzii, Coprococcus comes) and eukaryotes (Nemania serpens, Hyphopichia pseudoburtonii) were consistently enriched in responders of ≥2 cancer types or from ≥3 cohorts, contrasting with the depleted bacterium Hungatella hathewayi. Responder-associated species in each cancer were revealed, such as F. prausnitzii in MM and 6 species in NSCLC. These signature species influenced ICI efficacy by modulating CD8+ T cell activity in vitro and in mice. Moreover, bacterial and eukaryotic biomarkers showed great performance in predicting ICI response in patients from discovery and two validation cohorts (MM: area under the receiver operating characteristic curve [AUROC] = 72.27%-80.19%; NSCLC: AUROC = 72.70%-87.98%; RCC: AUROC = 83.33%-89.58%).

CONCLUSIONS

This study identified trans-kingdom microbial signatures associated with ICI in multi-cancer and specific cancer types. Trans-kingdom microbial biomarkers are potential predictors of ICI response in patients with cancer.

FUNDING

Funding information is shown in the acknowledgments.

Gut microbiome metabolites, molecular mimicry, and species-level variation drive long-term efficacy and adverse event outcomes in lung cancer survivors

BACKGROUND

The influence of the gut microbiota on long-term immune checkpoint inhibitor (ICI) efficacy and immune-related adverse events (irAEs) is poorly understood, as are the underlying mechanisms.

METHODS

We performed gut metagenome and metabolome sequencing of gut microbiotas from patients with lung cancer initially treated with anti-PD-1/PD-L1 therapy and explored the underlying mechanisms mediating long-term (median follow-up 1167 days) ICI responses and immune-related adverse events (irAEs). Results were validated in external, publicly-available datasets (Routy, Lee, and McCulloch cohorts).

FINDINGS

The ICI benefit group was enriched for propionate (P = 0.01) and butyrate/isobutyrate (P = 0.12) compared with the resistance group, which was validated in the McCulloch cohort (propionate P < 0.001, butyrate/isobutyrate P = 0.002). The acetyl-CoA pathway (P = 0.02) in beneficial species mainly mediated butyrate production. Microbiota sequences from irAE patients aligned with antigenic epitopes found in autoimmune diseases. Microbiotas of responsive patients contained more lung cancer-related antigens (P = 0.07), which was validated in the Routy cohort (P = 0.02). Escherichia coli and SGB15342 of Faecalibacterium prausnitzii showed strain-level variations corresponding to clinical phenotypes. Metabolome validation reviewed more abundant acetic acid (P = 0.03), propionic acid (P = 0.09), and butyric acid (P = 0.02) in the benefit group than the resistance group, and patients with higher acetic, propionic, and butyric acid levels had a longer progression-free survival and lower risk of tumor progression after adjusting for histopathological subtype and stage (P < 0.05).

INTERPRETATION

Long-term ICI survivors have coevolved a compact microbial community with high butyrate production, and molecular mimicry of autoimmune and tumor antigens by microbiota contribute to outcomes. These results not only characterize the gut microbiotas of patients who benefit long term from ICIs but pave the way for "smart" fecal microbiota transplantation. Registered in the Chinese Clinical Trial Registry (ChiCTR2000032088).

FUNDING

This work was supported by Beijing Natural Science Foundation (7232110), National High Level Hospital Clinical Research Funding (2022-PUMCH-A-072, 2023-PUMCH-C-054), CAMS Innovation Fund for Medical Sciences (CIFMS) (2022-I2M-C&T-B-010).

Host-pathobiont interactions in Crohn's disease

The mammalian intestine is colonized by trillions of microorganisms that are collectively referred to as the gut microbiota. The majority of symbionts have co-evolved with their host in a mutualistic relationship that benefits both. Under certain conditions, such as in Crohn's disease, a subtype of inflammatory bowel disease, some symbionts bloom to cause disease in genetically susceptible hosts. Although the identity and function of disease-causing microorganisms or pathobionts in Crohn's disease remain largely unknown, mounting evidence from animal models suggests that pathobionts triggering Crohn's disease-like colitis inhabit certain niches and penetrate the intestinal tissue to trigger inflammation. In this Review, we discuss the distinct niches occupied by intestinal symbionts and the evidence that pathobionts triggering Crohn's disease live in the mucus layer or near the intestinal epithelium. We also discuss how Crohn's disease-associated mutations in the host disrupt intestinal homeostasis by promoting the penetration and accumulation of pathobionts in the intestinal tissue. Finally, we discuss the potential role of microbiome-based interventions in precision therapeutic strategies for the treatment of Crohn's disease.

A comprehensive review of immune checkpoint inhibitors for cancer treatment

Immunology-based therapies are emerging as an effective cancer treatment, using the body's immune system to target tumors. Immune checkpoints, which regulate immune responses to prevent tissue damage and autoimmunity, are often exploited by cancer cells to avoid destruction. The discovery of checkpoint proteins like PD-1/PD-L1 and CTLA-4 was pivotal in developing cancer immunotherapy. Immune checkpoint inhibitors (ICIs) have shown great success, with FDA-approved drugs like PD-1 inhibitors (Nivolumab, Pembrolizumab, Cemiplimab), PD-L1 inhibitors (Atezolizumab, Durvalumab, Avelumab), and CTLA-4 inhibitors (Ipilimumab, Tremelimumab), alongside LAG-3 inhibitor Relatlimab. Research continues on new checkpoints like TIM-3, VISTA, B7-H3, BTLA, and TIGIT. Biomarkers like PDL-1 expression, tumor mutation burden, interferon-γ presence, microbiome composition, and extracellular matrix characteristics play a crucial role in predicting responses to immunotherapy with checkpoint inhibitors. Despite their effectiveness, not all patients experience the same level of benefit, and organ-specific immune-related adverse events (irAEs) such as rash or itching, colitis, diarrhea, hyperthyroidism, and hypothyroidism may occur. Given the rapid advancements in this field and the variability in patient outcomes, there is an urgent need for a comprehensive review that consolidates the latest findings on immune checkpoint inhibitors, covering their clinical status, biomarkers, resistance mechanisms, strategies to overcome resistance, and associated adverse effects. This review aims to fill this gap by providing an analysis of the current clinical status of ICIs, emerging biomarkers, mechanisms of resistance, strategies to enhance therapeutic efficacy, and assessment of adverse effects. This review is crucial to furthering our understanding of ICIs and optimizing their application in cancer therapy.

Assessing the causal relationship between gut microbiota and prostate cancer: A two-sample Mendelian randomization study

BACKGROUND

Numerous studies indicate that the gut microbiome is closely associated with prostate cancer (PCa), however, owing to various confounding factors, the causal relationship between gut microbiota and PCa remains unclear.

METHODS

A 2-sample Mendelian randomization (MR) analysis utilized genome-wide association study (GWAS) data on the gut microbiota of 18,340 participants and GWAS summary statistics on PCa involving 46,3010 participants. Inverse variance weighted (IVW) served as the primary method, complemented by the MR-Egger method, weighted median method (WME), simple mode method (SM), and weighted mode method (WM). Finally, to confirm the robustness of the results, heterogeneity test, pleiotropy test, and leave-one-out sensitivity test were conducted.

RESULTS

IVW analysis revealed that 12 specific gut microbial taxa were potentially causally associated with PCa; the genera Victivallis, Akkermansia, Odoribacter, Butyrivibrio, and the families Enterobacteriaceae, Verrucomicrobiaceae, as well as the orders Verrucomicrobiales, Enterobacteriales and the class Verrucomicrobiae, were found to be positively associated with PCa risk. Conversely, the genera Eubacterium ruminantium group, Candidatus Soleaferrea, and RuminococcaceaeUCG003 were negatively associated with PCa risk.

CONCLUSIONS

Our MR study's results support a genetically predicted causal relationship between the gut microbiota and PCa, and we identified 12 specific gut microbial taxa. These findings could offer new targets for PCa screening and treatment.

Impact of chronic stress on intestinal mucosal immunity in colorectal cancer progression

Chronic stress is a significant risk factor that contributes to the progression of colorectal cancer (CRC) and has garnered considerable attention in recent research. It influences the distribution and function of immune cells within the intestinal mucosa through the "brain-gut" axis, altering cytokine and chemokine secretion and creating an immunosuppressive tumor microenvironment. The intestine, often called the "second brain," is particularly susceptible to the effects of chronic stress. Cytokines and chemokines in intestinal mucosal immunity（IMI） are closely linked to CRC cells' proliferation, metastasis, and drug resistance under chronic stress. Recently, antidepressants have emerged as potential therapeutic agents for CRC, possibly by modulating IMI to restore homeostasis and exert anti-tumor effects. This article reviews the role of chronic stress in promoting CRC progression via its impact on intestinal mucosal immunity, explores potential targets within the intestinal mucosa under chronic stress, and proposes new approaches for CRC treatment.

Guiding treatment decisions in renal cell carcinoma: the role of biomarkers and clinical factors

PURPOSE OF REVIEW

Immune checkpoint inhibitors (ICIs) have transformed the treatment landscape for metastatic renal cell carcinoma (mRCC), significantly improving overall survival and achieving durable responses. This review is timely due to the increasing number of ICI-based regimens now considered standard care for RCC. There is an urgent need to identify reliable biomarkers that can predict therapeutic responses and resistance, a key challenge in current research.

RECENT FINDINGS

While tumor-specific factors such as pathological characteristics, genomic mutations, and transcriptional profiles have been extensively studied, no definitive predictive biomarker has yet emerged. Additionally, advanced technologies are being explored to address tumor heterogeneity. Recent research has focused on novel areas such as the microbiome, radiomics, and spatial transcriptomics, which show promise as potential biomarkers.

SUMMARY

The translation of these emerging biomarker findings into clinical practice is essential to improving personalized treatment strategies for RCC. Until reliable biomarkers are clinically available, clinical factors may play a pivotal role in guiding individualized treatment decisions to optimize patient outcomes.

Next-generation IgA-SEQ allows for high-throughput, anaerobic, and metagenomic assessment of IgA-coated bacteria

BACKGROUND

The intestinal microbiota plays a significant role in maintaining systemic and intestinal homeostasis, but can also influence diseases such as inflammatory bowel disease (IBD) and cancer. Certain bacterial species within the intestinal tract can chronically activate the immune system, leading to low-grade intestinal inflammation. As a result, plasma cells produce high levels of secretory antigen-specific immunoglobulin A (IgA), which coats the immunostimulatory bacteria. This IgA immune response against intestinal bacteria may be associated with the maintenance of homeostasis and health, as well as disease. Unraveling this dichotomy and identifying the immunostimulatory bacteria is crucial for understanding the relationship between the intestinal microbiota and the immune system, and their role in health and disease. IgA-SEQ technology has successfully identified immunostimulatory, IgA-coated bacteria from fecal material. However, the original technology is time-consuming and has limited downstream applications. In this study, we aimed to develop a next-generation, high-throughput, magnet-based sorting approach (ng-IgA-SEQ) to overcome the limitations of the original IgA-SEQ protocol.

RESULTS

We show, in various settings of complexity ranging from simple bacterial mixtures to human fecal samples, that our magnetic 96-well plate-based ng-IgA-SEQ protocol is highly efficient at sorting and identifying IgA-coated bacteria in a high-throughput and time efficient manner. Furthermore, we performed a comparative analysis between different IgA-SEQ protocols, highlighting that the original FACS-based IgA-SEQ approach overlooks certain nuances of IgA-coated bacteria, due to the low yield of sorted bacteria. Additionally, magnetic-based ng-IgA-SEQ allows for novel downstream applications. Firstly, as a proof-of-concept, we performed metagenomic shotgun sequencing on 10 human fecal samples to identify IgA-coated bacterial strains and associated pathways and CAZymes. Secondly, we successfully isolated and cultured IgA-coated bacteria by performing the isolation protocol under anaerobic conditions.

CONCLUSIONS

Our magnetic 96-well plate-based high-throughput next-generation IgA-SEQ technology efficiently identifies a great number of IgA-coated bacteria from fecal samples. This paves the way for analyzing large cohorts as well as novel downstream applications, including shotgun metagenomic sequencing, culturomics, and various functional assays. These downstream applications are essential to unravel the role of immunostimulatory bacteria in health and disease. Video Abstract.

Gastrointestinal Microbiota in Gastric Cancer: Potential Mechanisms and Clinical Applications-A Literature Review

Emerging evidence highlights the crucial role of gastrointestinal microbiota in the pathogenesis of gastric cancer. Helicobacter pylori (H. pylori) infection stands out as a primary pathogenic factor. However, interventions such as anti-H. pylori therapy, gastric surgeries, immunotherapy, and chronic inflammation significantly remodel the gastric microbiome, implicating a broader spectrum of microorganisms in cancer development. These microbial populations can modulate gastric carcinogenesis through various mechanisms, including sustained chronic inflammation, bacterial genotoxins, alterations in short-chain fatty acids, elevated gastrointestinal bile acids, impaired mucus barrier function, and increased concentrations of N-nitrosamines and lactic acid. The dynamic changes in gut microbiota also critically influence the outcomes of anti-cancer therapies by modifying drug bioavailability and metabolism, thus affecting therapeutic efficacy and side effect profiles. Additionally, the effectiveness of radiotherapy can be significantly impacted by gut microbiota alterations. Novel therapeutic strategies targeting the microbiome, such as dietary interventions, probiotic and synbiotic supplementation, and fecal microbiota transplantation, are showing promise in cancer treatment. Understanding the intricate relationship between the gut microbiota and gastric cancer is essential for developing new, evidence-based approaches to the prevention and treatment of this malignancy.

Detrimental effect of an early exposure to antibiotics on the outcomes of immunotherapy in a multi-tumor cohort of patients

BACKGROUND

Immune checkpoint inhibitors (ICI) have changed the therapeutic landscape of many solid tumors. Modulation of the intestinal microbiota by antibiotics (Abx) has been suggested to impact on ICI outcomes.

METHODS

Retrospective analysis of 475 patients with advanced solid tumors treated with ICI from 2015 to 2022. For each patient, the use of Abx was recorded from 1 month before ICI initiation until disease progression or death. The impact of Abx on objective response rates (ORR), disease control rates (DCR), progression-free survival (PFS), and overall survival (OS) was analyzed. Kaplan-Meier and log-rank tests were used to compare survival outcomes.

RESULTS

In total 475 patients with advanced solid tumors were evaluated. Median age was 67.5 years and performance status (PS) was 0-1 in 84.6%. 66.5% of patients received Abx during treatment with ICI, mainly beta-lactams (53.8%) and quinolones (35.9%). The early exposure to Abx (from 60 days before to 42 days after the first cycle of ICI) was associated with a lower ORR (27.4% vs 39.4%; P < .01), a lower DCR (37.3% vs 57.4%; P < .001), lower PFS (16.8 m vs 27.8 m; HR 0.66; P < .001]) and lower OS (2.5 m vs 6.6 m; HR 0.68; P = .001]). The negative impact of Abx on OS and PFS was confirmed by a multivariable analysis. This effect was not observed among patients receiving Abx after 6 weeks from ICI initiation.

CONCLUSIONS

Our results validate the hypothesis of a detrimental effect of an early exposure to Abxon the efficacy of ICI in a multi-tumor cohort of patients.

Integrative multi-omics analysis reveals the role of tumor-associated endothelial cells and their signature in prognosis of intrahepatic cholangiocarcinoma

This study aims to investigate the interplay between tumor-associated endothelial cells (TECs) and immune cells within the tumor microenvironment (TME) and its impact on tumor prognosis. We conducted single-cell RNA sequencing (scRNA-seq) of tumor, normal, and lymph node tissues obtained from intrahepatic cholangiocarcinoma (ICC) patients to reveal the role of TECs in tumor angiogenesis and their significant heterogeneity. Meanwhile, we identified genes highly expressed in TECs and constructed TEC signatures (TEC.Sig). Next, we calculated TEC scores of samples based on TEC.Sig. Patients with higher TEC scores exhibited a higher frequency of KRAS mutations, which was associated with increased infiltration of neutrophils and immature dendritic cells (iDCs), and decreased numbers of natural killer (NK), CD4 + T, and CD8 + T effector memory (Tem) cells, indicating an inflammation-dominated immunosuppressive phenotype. In contrast, BAP1 mutations and CXCL12 overexpression showed a contrasting trend. Spatial transcriptomics analysis and histological experiments further confirmed that TECs interacted with various tumor-killing immune cells through the CXCL12/CXCR4 axis. Multiple tumor immunotherapy datasets confirmed that the TEC.Sig could predict patient responses to immunotherapy. The TEC score is a promising and reliable biomarker for predicting genetic mutations and prognosis in ICC patients. Enhancing the regulation of the CXCL12/CXCR4 signaling pathway may represent a potential novel therapeutic target for ICC treatment.

Traditional Chinese medicine enhances the effectiveness of immune checkpoint inhibitors in tumor treatment: A mechanism discussion

ETHNOPHARMACOLOGICAL RELEVANCE

Immune checkpoint inhibitors (ICIs) have altered the landscape of tumor immunotherapy, offering novel therapeutic approaches alongside surgery, chemotherapy, and radiotherapy and significantly improving survival benefits. However, their clinical efficacy is limited in some patients, and their use may cause immune-related adverse events (irAEs). Integrating traditional Chinese medicine (TCM) with ICIs has demonstrated the potential to boost sensitization and reduce toxicity. Clinical trials and experimental explorations have confirmed that TCM and its active components synergistically enhance the effectiveness of ICIs.

AIMS

This narrative review summarizes the TCM practices that enhance the clinical efficacy and reduce irAEs of ICIs. This paper also summarizes the mechanism of experimental studies on the synergies of Chinese herbal decoctions, Chinese herbal preparation, and Chinese herbal active ingredients. Most of the studies on TCM combined with ICIs are basic experiments. We discussed the mechanism of TCM enhanced ICIs to provide reference for the research and development of TCM adjuvant immunotherapy.

METHODS

We conducted a literature search using PubMed and Chinese National Knowledge Infrastructure databases, with a focus on herbal decoction, Chinese medicine preparations, and active ingredients that boost the effectiveness of ICIs and reduce irAEs. The search keywords were "ICIs and traditional Chinese medicine", "PD-1 and traditional Chinese medicine", "PD-L1 and traditional Chinese medicine", "CTLA-4 and traditional Chinese medicine", "IDO1 and traditional Chinese medicine", "Tim-3 and traditional Chinese medicine", "TIGIT and traditional Chinese medicine", "irAEs and traditional Chinese medicine". The search period was from May 2014 to May 2024. Articles involving the use of TCM or its components in combination with ICIs and investigating the underlying mechanisms were screened. Finally, 30 Chinese medicines used in combination with ICIs were obtained to explore the mechanism. In the part of immune checkpoint molecules other than PD-1, there were few studies on the combined application of TCM, so studies involving the regulation of immune checkpoint molecules by TCM were included.

RESULTS

TCM has been shown to boost the effectiveness of ICIs and reduce irAEs. Researchers indicate that TCM and its active components can work synergistically with ICIs by regulating immune checkpoints PD-1, PD-L1, CTLA-4, and IDO1, regulating intestinal flora, improving tumor microenvironment and more.

CONCLUSIONS

Combining TCM with ICIs can play a better anti-tumor role, but larger samples and high-quality clinical trials are necessary to confirm this. Many Chinese medicines and their ingredients have been shown to sensitize ICIs in experimental studies, which provides a rich choice for the subsequent development of ICI enhancers.

Parvimonas micra forms a distinct bacterial network with oral pathobionts in colorectal cancer patients

BACKGROUND

Mounting evidence suggests a significant role of the gut microbiota in the development and progression of colorectal cancer (CRC). In particular, an over-representation of oral pathogens has been linked to CRC. The aim of this study was to further investigate the faecal microbial landscape of CRC patients, with a focus on the oral pathogens Parvimonas micra and Fusobacterium nucleatum.

METHODS

In this study, 16S rRNA sequencing was conducted using faecal samples from CRC patients (n = 275) and controls without pathological findings (n = 95).

RESULTS

We discovered a significant difference in microbial composition depending on tumour location and microsatellite instability (MSI) status, with P. micra, F. nucleatum, and Peptostreptococcus stomatis found to be more abundant in patients with MSI tumours. Moreover, P. micra and F. nucleatum were associated with a cluster of CRC-related bacteria including Bacteroides fragilis as well as with other oral pathogens such as P. stomatis and various Porphyromonas species. This cluster was distinctly different in the control group, suggesting its potential linkage with CRC.

CONCLUSIONS

Our results suggest a similar distribution of several CRC-associated bacteria within CRC patients, underscoring the importance of considering the concomitant presence of bacterial species in studies investigating the mechanisms of CRC development and progression.

A comprehensive update on the immunoregulatory mechanisms of Akkermansia muciniphila: insights into active ingredients, metabolites, and nutrient-driven modulation

Akkermansia muciniphila (A. muciniphila) has gained recognition as a pioneering probiotic, exhibiting considerable potential to enhance immune conditions across both humans and animals. The health benefits of A. muciniphila are attributed to its various components, including outer membrane proteins (PilQ and Amuc_1100), secreted proteins (P9 and AmTARS), extracellular vesicles, and metabolites such as SCFAs, ornithine lipids, γ-aminobutyric acid, cobalamin, and inosine. The dynamic control of the mucus layer by A. muciniphila plays a crucial role in regulating intestinal mucosal immunity. Furthermore, A. muciniphila modulates immune function by interacting with macrophages, dendritic cells, T lymphocytes, and Paneth cells. Increasing the abundance of A. muciniphila in the gut through nutritional strategies represents a safe and effective means to augment immune function. Various polyphenols, oligosaccharides, and polysaccharides have been shown to elevate the levels of this bacterium, thereby contributing to favorable immunoregulatory outcomes. This paper delves into the latest research advancements related to the probiotic mechanisms of A. muciniphila and provides an overview of the current understanding of how its abundance responds to nutrients. These insights offer a theoretical foundation for the utilization of A. muciniphila in immunoregulation.

Hepatocellular Carcinoma Immunotherapy: Predictors of Response, Issues, and Challenges

Immune checkpoint inhibitors (ICIs), such as durvalumab, tremelimumab, and atezolizumab, have emerged as a significant therapeutic option for the treatment of hepatocellular carcinoma (HCC). In fact, the efficacy of ICIs as single agents or as part of combination therapies has been demonstrated in practice-changing phase III clinical trials. However, ICIs confront several difficulties, including the lack of predictive biomarkers, primary and secondary drug resistance, and treatment-related side effects. Herein, we provide an overview of current issues and future challenges in this setting.

Influence of the gut microbiota on immune cell interactions and cancer treatment

The tumour microenvironment represents a novel frontier in oncological research. Over the past decade, accumulating evidence has underscored the importance of the tumour microenvironment (TME), including tumour cells, stromal cells, immune cells, and various secreted factors, which collectively influence tumour growth, invasion, and responses to therapeutic agents. Immune cells within the TME are now widely acknowledged to play pivotal roles in tumour development and treatment. While some perspectives have posited that immune cells within the TME facilitate tumour progression and confer resistance to therapeutic interventions, contrasting conclusions also exist. Affirmative and negative conclusions appear to be context dependent, and a unified consensus has yet to be reached. The burgeoning body of research on the relationship between the gut microbiota and tumours in recent years has led to a growing understanding. Most studies have indicated that specific components of the gut microbiota, such as unique bacterial communities or specific secretory factors, play diverse roles in regulating immune cells within the TME, thereby influencing the prognosis and outcomes of cancer treatments. A detailed understanding of these factors could provide novel insights into the TME and cancer therapy. In this study, we aimed to synthesise information on the interactions between the gut microbiota and immune cells within the TME, providing an in-depth exploration of the potential guiding implications for future cancer therapies.

Fusobacterium nucleatum facilitates anti-PD-1 therapy in microsatellite stable colorectal cancer

Microsatellite stable (MSS) colorectal cancers (CRCs) are often resistant to anti-programmed death-1 (PD-1) therapy. Here, we show that a CRC pathogen, Fusobacterium nucleatum (Fn), paradoxically sensitizes MSS CRC to anti-PD-1. Fecal microbiota transplantation (FMT) from patients with Fn-high MSS CRC to germ-free mice bearing MSS CRC confers sensitivity to anti-PD-1 compared to FMT from Fn-low counterparts. Single Fn administration also potentiates anti-PD-1 efficacy in murine allografts and CD34+-humanized mice bearing MSS CRC. Mechanistically, we demonstrate that intratumoral Fn generates abundant butyric acid, which inhibits histone deacetylase (HDAC) 3/8 in CD8+ T cells, inducing Tbx21 promoter H3K27 acetylation and expression. TBX21 transcriptionally represses PD-1, alleviating CD8+ T cell exhaustion and promoting effector function. Supporting this notion, knockout of a butyric acid-producing gene in Fn abolishes its anti-PD-1 boosting effect. In patients with MSS CRC, high intratumoral Fn predicts favorable response to anti-PD-1 therapy, indicating Fn as a potential biomarker of immunotherapy response in MSS CRC.

Prostate cancer microenvironment: multidimensional regulation of immune cells, vascular system, stromal cells, and microbiota

BACKGROUND

Prostate cancer (PCa) is one of the most prevalent malignancies in males worldwide. Increasing research attention has focused on the PCa microenvironment, which plays a crucial role in tumor progression and therapy resistance. This review aims to provide a comprehensive overview of the key components of the PCa microenvironment, including immune cells, vascular systems, stromal cells, and microbiota, and explore their implications for diagnosis and treatment.

METHODS

Keywords such as "prostate cancer", "tumor microenvironment", "immune cells", "vascular system", "stromal cells", and "microbiota" were used for literature retrieval through online databases including PubMed and Web of Science. Studies related to the PCa microenvironment were selected, with a particular focus on those discussing the roles of immune cells, vascular systems, stromal cells, and microbiota in the development, progression, and treatment of PCa. The selection criteria prioritized peer-reviewed articles published in the last five years, aiming to summarize and analyze the latest research advancements and clinical relevance regarding the PCa microenvironment.

RESULTS

The PCa microenvironment is highly complex and dynamic, with immune cells contributing to immunosuppressive conditions, stromal cells promoting tumor growth, and microbiota potentially affecting androgen metabolism. Vascular systems support angiogenesis, which fosters tumor expansion. Understanding these components offers insight into the mechanisms driving PCa progression and opens avenues for novel therapeutic strategies targeting the tumor microenvironment.

CONCLUSIONS

A deeper understanding of the PCa microenvironment is crucial for advancing diagnostic techniques and developing precision therapies. This review highlights the potential of targeting the microenvironment to improve patient outcomes, emphasizing its significance in the broader context of PCa research and treatment innovation.

Chemotherapy combined with immune checkpoint inhibitors may overcome the detrimental effect of high neutrophil-to-lymphocyte ratio prior to treatment in esophageal cancer patients

Introduction

Immune checkpoint inhibitors (ICIs) have emerged as a promising treatment option for esophageal cancer (EC). Although ICIs enable long-term survival in some patients, the efficacy of ICIs varies widely among patients. Therefore, predictive biomarkers are necessary for identifying patients who are most likely to benefit from ICIs to improve the efficacy of the treatment. We retrospectively analyzed the outcomes of combination therapy, including nivolumab plus ipilimumab or chemotherapy plus anti-programmed cell death 1 (PD-1) antibodies in our institute to identify biomarkers.

Methods

Twenty-seven patients received nivolumab plus ipilimumab, and thirty-six patients received chemotherapy plus anti-PD-1 antibodies were included in this study. We analyzed patient characteristics, efficacy, and safety. Multivariable analysis of biomarkers evaluated the correlation among overall survival (OS), progression-free survival (PFS), and the following variables: body mass index, performance status, neutrophil-to-lymphocyte ratio (NLR), C-reactive protein level, and albumin level before treatment.

Results

In multivariable analysis, albumin level was significantly correlated with PFS in the cisplatin plus 5-fluorouracil (CF) plus pembrolizumab group. NLR and albumin level were significantly correlated with OS in the nivolumab plus ipilimumab group. Other variables, including PS, BMI, and CRP did not correlate with any of the outcomes.

Conclusions

High NLR in EC patients prior to treatment was significantly less effective for ICIs. In chemotherapy combined with ICIs, NLR before the treatment was not associated with treatment efficacy, suggesting combination chemotherapy may be beneficial for EC patients with high NLR. NLR may be an indicator of immunocompetence in anti-tumor immunity and a convenient predictive biomarker for selecting appropriate treatments including ICIs.

Cancer-induced systemic pre-conditioning of distant organs: building a niche for metastatic cells

From their early genesis, tumour cells integrate with the surrounding normal cells to form an abnormal structure that is tightly integrated with the host organism via blood and lymphatic vessels and even neural associations. Using these connections, emerging cancers send a plethora of mediators that efficiently perturb the entire organism and induce changes in distant tissues. These perturbations serendipitously favour early metastatic establishment by promoting a more favourable tissue environment (niche) that supports the persistence of disseminated tumour cells within a foreign tissue. Because the establishment of early metastatic niches represents a key limiting step for metastasis, the creation of a more suitable pre-conditioned tissue strongly enhances metastatic success. In this Review, we provide an updated view of the mechanisms and mediators of primary tumours described so far that induce a pro-metastatic conditioning of distant organs, which favours early metastatic niche formation. We reflect on the nature of cancer-induced systemic conditioning, considering that non-cancer-dependent perturbations of tissue homeostasis are also able to trigger pro-metastatic conditioning. We argue that a more holistic view of the processes catalysing metastatic progression is needed to identify preventive or therapeutic opportunities.

Combination of lipopolysaccharide and polygalacturonic acid exerts antitumor activity and augments anti-PD-L1 immunotherapy

Polygalacturonic acid (PGA) restored the alpha-diversity of gut microbiota and promoted T cells infiltration in tumors. Here, we investigated whether oral administration of PGA could improve the anti-cancer effect of lipopolysaccharide-encapsulated PLGA-PEG-PLGA (LPS/PPP) in mice bearing CT26 tumors. Hydrogels with rapid thermogelling properties can achieve localized and controlled release of LPS, thus retaining the anti-cancer effect of LPS and avoiding a robust inflammatory storm. LPS/PPP promoted M1 macrophage polarization, TLR4 expression, and phagocytosis in tumors. The combination of PGA and LPS/PPP (PGA_LPS) notably repressed CT26 tumor growth and the inhibition rate reached 67.6 %. PGA_LPS triggered the recruitment of helper and cytotoxic T cells, IFN-γ level, decreased the proportion of immunosuppressive regulatory T cells. PGA_LPS also restored the beta-diversity of gut microbiota and increased short chain fatty acids abundance (butyric acid, 608.93 % vs. model group, P < 0.01). PGA_LPS followed by αPD-L1 resulted in obvious inhibition of both CT26 and 4T1 tumor growth, promoted cleaved-caspase 3 and Bax expression, T cell responses and the rescue of T cells exhaustion. These results confirmed that PGA_LPS reinforced the anticancer effect of αPD-L1, probably by reshaping the tumor microenvironment and intestinal flora, which sheds light on the combination approach to intensify the effect of immune checkpoint inhibitors.