Anticancer immunotherapy by CTLA-4 blockade relies on the gut microbiota

Targeting gut microbiota to regulate the adaptive immune response in atherosclerosis

Atherosclerosis, the leading cause of death worldwide, is a chronic inflammatory disease leading to the accumulation of lipid-rich plaques in the intima of large and medium-sized arteries. Accumulating evidence indicates the important regulatory role of the adaptive immune system in atherosclerosis during all stages of the disease. The gut microbiome has also become a key regulator of atherosclerosis and immunomodulation. Whilst existing research extensively explores the impact of the microbiome on the innate immune system, only a handful of studies have explored the regulatory capacity of the microbiome on the adaptive immune system to modulate atherogenesis. Building on these concepts and the pitfalls on the gut microbiota and adaptive immune response interaction, this review explores potential strategies to therapeutically target the microbiome, including the use of prebiotics and vaccinations, which could influence the adaptive immune response and consequently plaque composition and development.

A comprehensive insights of cancer immunotherapy resistance

Cancer is a major global health issue that is usually treated with multiple therapies, such as chemotherapy and targeted therapies like immunotherapy. Immunotherapy is a new and alternative approach to treating various types of cancer that are difficult to treat with other methods. Although immune checkpoint inhibitors have shown promise for long-term efficacy, they have limited effectiveness in common cancer types such as breast, prostate, and lung. Some patients do not respond to immunotherapy, while others develop resistance to the treatment over time, which is classified as primary or acquired resistance. Cancer immunotherapy, specifically immune checkpoint inhibitor-based resistance involves multiple factors such as genes, metabolism, inflammation, and angiogenesis. However, cutting-edge research has identified the mechanisms of immunotherapy resistance and possible solutions. Current research may improve biomarker identification and modify treatment strategies, which will lead to better clinical outcomes. This review provides a comprehensive discussion of the current mechanisms of immunotherapy resistance, related biomarker modulation, and strategies to overcome resistance.

Synergistic Interactions Between Probiotics and Anticancer Drugs: Mechanisms, Benefits, and Challenges

Research into the role of probiotics-often referred to as "living supplements"-in cancer therapy is still in its early stages, and uncertainties regarding their effectiveness remain. Relevantly, chemopreventive and therapeutic effects of probiotics have been determined. There is also substantial evidence supporting their potential in cancer treatment such as immunotherapy. Probiotics employ various mechanisms to inhibit cancer initiation and progression. These include colonizing and protecting the gastrointestinal tract (GIT), producing metabolites, inducing apoptosis and autophagy, exerting anti-inflammatory properties, preventing metastasis, enhancing the effectiveness of immune checkpoint inhibitors (ICIs), promoting cancer-specific T cell infiltration, arresting the cell cycle, and exhibiting direct or indirect synergistic effects with anticancer drugs. Additionally, probiotics have been shown to activate tumor suppressor genes and inhibit pro-inflammatory transcription factors. They also increase reactive oxygen species production within cancer cells. Synergistic interactions between probiotics and various anticancer drugs, such as cisplatin, cyclophosphamide, 5-fluorouracil, trastuzumab, nivolumab, ipilimumab, apatinib, gemcitabine, tamoxifen, sorafenib, celecoxib and irinotecan have been observed. The combination of probiotics with anticancer drugs holds promise in overcoming drug resistance, reducing recurrence, minimizing side effects, and lowering treatment costs. In addition, fecal microbiota transplantation (FMT) and prebiotics supplementation has increased cytotoxic T cells within tumors. However, probiotics may leave some adverse effects such as risk of infection and gastrointestinal effects, antagonistic effects with drugs, and different responses among patients. These findings highlight insights for considering specific strains and engineered probiotic applications, preferred doses and timing of treatment, and personalized therapies to enhance the efficacy of cancer therapy. Accordingly, targeted interventions and guidelines establishment needs extensive randomized controlled trials as probiotic-based cancer therapy has not been approved by Food and Drug Administration (FDA).

Functional regulation of cytotoxic T cells by gut microbial metabolites

Metabolites from gut microbes have a wide range of functions within the host body. One important function of these metabolites is to either positively or negatively control CD8+ cytotoxic T lymphocytes (CTLs), which can kill cancer and virus-infected cells. In healthy conditions, gut microbes produce a mixture of metabolites that promote CTL activity but also suppress excessive inflammatory responses. However, gut microbial dysbiosis occurs in patients with cancer, and this leads to changes in the production of gut microbial metabolites that can suppress CTL activity, promote inflammatory responses, and/or aid cancer growth. Decreased levels of CTL-promoting metabolites such as short-chain fatty acids, indole metabolites and polyamines but increased levels of CTL-suppressing metabolites, such as certain bile acids along with oncogenic metabolites, have been observed in patients with cancer. This review summarizes the altered production of major microbial metabolites in patients with cancer and discusses the impact of these changes on anti-cancer CTL responses.

Crosstalk between Gut Microbiota and Cancer Immunotherapy: Present Investigations and Future Perspective

Gut microbiota is crucial for protecting the homeostasis of immune locally and systemically, and its dysbiosis is essentially correlated to tumorigenesis, cancer progression, and refractoriness to cancer treatments, including the novel immunotherapy. Increasing evidence unravel the intricate role of gut microbiota in reshaping tumor microenvironment and affecting the efficacy and toxicities of immunotherapy, which shed more light on the future applications of gut microbiota in efficacious biomarker and combination treatment of immunotherapy. To better grasp the underlying crosstalk between gut microbiota and immunotherapy, more experimental and clinical trials are indispensable for the customized gut microbiota-based treatments in cancer patients undergoing immunotherapy.

Hidden Partner of Immunity: Microbiome as an Innovative Companion in Immunotherapy

Recent studies have highlighted that the microbiome is the essential factor that can modulate the clinical activity of immunotherapy. However, the role of the microbiome varies significantly across different immunotherapies, suggesting that it is critical to understand the precise function of the microbiome in each type of immunotherapy. While many previous studies primarily focus on summarizing the role of the microbiome in immune checkpoint inhibitors, we seek to explore a novel aspect of the microbiome in other immunotherapies such as mesenchymal stem cell therapy, chimeric antigen receptor T cell therapy, and antibodies-based therapy (e.g., adalimumab, infliximab, bevacizumab, denosumab, etc.) which are rarely summarized in previous reviews. Moreover, we highlight innovative strategies for utilizing microbiome and microbial metabolites to enhance the clinical response of immunotherapy. Collectively, we believe that our manuscript will provide novel insights and innovative approaches to the researchers, which could drive the development of the next generation of personalized therapeutic interventions using microbiomes.

A bibliometric study on the impact of gut microbiota on the efficacy of immune checkpoint inhibitors in cancer patients: analysis of the top 100 cited articles

Background

Immune checkpoint inhibitors (ICIs) have transformed oncological treatment by modulating immune responses against tumors. However, their efficacy is subject to inter-patient variability and is associated with immune-related adverse events (irAEs). The human gut microbiota, a complex microbial ecosystem, is increasingly implicated in modulating responses to ICIs. This bibliometric analysis examines the 100 most-cited articles to elucidate trends and advancements in research concerning the gut microbiota's impact on ICI efficacy.

Methods

A systematic literature retrieval was conducted within the Web of Science Core Collection (WoSCC), focusing on the 100 most-cited articles. VOSviewer and CiteSpace were utilized for bibliometric analysis, examining collaborative patterns and keyword co-occurrences. The relationship between citing and cited entities was analyzed, and burst ranking identified research hotspots based on citation frequency.

Results

The 100 most-cited publications encompassed a range of disciplines, with a predominance of oncological research. The United States and China were leading in publication volume, with France and Canada also contributing significantly. French institutions, particularly INSERM and Université Paris Cite, were prolific. Routy, Bertrand and Zitvogel, Laurence were prominent among high-impact authors. Dominant keywords included "gut microbiota," "immunotherapy," "efficacy," and "cancer." The article by Routy et al. (2018) was the most frequently cited.

Conclusions

This study highlights the significant role of the gut microbiota in ICI development and efficacy, emphasizing the necessity for international and interdisciplinary collaboration. The research is progressively focusing on managing immunotherapy side effects and optimizing treatment strategies. Challenges, including individual variability in gut microbiota composition, persist. Further research is imperative to exploit the potential of the gut microbiota in cancer therapy, advocating for personalized approaches and a more profound comprehension of the underlying mechanisms.

Advances in the understanding and therapeutic manipulation of cancer immune responsiveness: a Society for Immunotherapy of Cancer (SITC) review

Cancer immunotherapy-including immune checkpoint inhibition (ICI) and adoptive cell therapy (ACT)-has become a standard, potentially curative treatment for a subset of advanced solid and liquid tumors. However, most patients with cancer do not benefit from the rapidly evolving improvements in the understanding of principal mechanisms determining cancer immune responsiveness (CIR); including patient-specific genetically determined and acquired factors, as well as intrinsic cancer cell biology. Though CIR is multifactorial, fundamental concepts are emerging that should be considered for the design of novel therapeutic strategies and related clinical studies. Recent advancements as well as novel approaches to address the limitations of current treatments are discussed here, with a specific focus on ICI and ACT.

From Gut to Brain: The Impact of Short-Chain Fatty Acids on Brain Cancer

The primary source of short-chain fatty acids (SCFAs), now recognized as critical mediators of host health, particularly in the context of neurobiology and cancer development, is the gut microbiota's fermentation of dietary fibers. Recent research highlights the complex influence of SCFAs, such as acetate, propionate, and butyrate, on brain cancer progression. These SCFAs impact immune modulation and the tumor microenvironment, particularly in brain tumors like glioma. They play a critical role in regulating cellular processes, including apoptosis, cell differentiation, and inflammation. Moreover, studies have linked SCFAs to maintaining the integrity of the blood-brain barrier (BBB), suggesting a protective role in preventing tumor infiltration and enhancing anti-tumor immunity. As our understanding of the gut-brain axis deepens, it becomes increasingly important to investigate SCFAs' therapeutic potential in brain cancer management. Looking into how SCFAs affect brain tumor cells and the environment around them could lead to new ways to prevent and treat these diseases, which could lead to better outcomes for people who are dealing with these challenging cancers.

Resistance mechanisms to immune checkpoint inhibitors: updated insights

The last decade has witnessed unprecedented succusses with the use of immune checkpoint inhibitors in treating cancer. Nevertheless, the proportion of patients who respond favorably to the treatment remained rather modest, partially due to treatment resistance. This has fueled a wave of research into potential mechanisms of resistance to immune checkpoint inhibitors which can be classified into primary resistance or acquired resistance after an initial response. In the current review, we summarize what is known so far about the mechanisms of resistance in terms of being tumor-intrinsic or tumor-extrinsic taking into account the multimodal crosstalk between the tumor, immune system compartment and other host-related factors.

Understanding the role of the gut microbiome in solid tumor responses to immune checkpoint inhibitors for personalized therapeutic strategies: a review

Immunotherapy, especially immune checkpoint inhibitor (ICI) therapy, has yielded remarkable outcomes for some patients with solid cancers, but others do not respond to these treatments. Recent research has identified the gut microbiota as a key modulator of immune responses, suggesting that its composition is closely linked to responses to ICI therapy in cancer treatment. As a result, the gut microbiome is gaining attention as a potential biomarker for predicting individual responses to ICI therapy and as a target for enhancing treatment efficacy. In this review, we discuss key findings from human observational studies assessing the effect of antibiotic use prior to ICI therapy on outcomes and identifying specific gut bacteria associated with favorable and unfavorable responses. Moreover, we review studies investigating the possibility of patient outcome prediction using machine learning models based on gut microbiome data before starting ICI therapy and clinical trials exploring whether gut microbiota modulation, for example via fecal microbiota transplantation or live biotherapeutic products, can improve results of ICI therapy in patients with cancer. We also briefly discuss the mechanisms through which the gut microbial-derived products influence immunotherapy effectiveness. Further research is necessary to fully understand the complex interactions between the host, gut microbiota, and immunotherapy and to develop personalized strategies that optimize responses to ICI therapy.

Baseline colitogenicity and acute perturbations of gut microbiota in immunotherapy-related colitis

Immunotherapy-related colitis (irC) frequently emerges as an immune-related adverse event during immune checkpoint inhibitor therapy and is presumably influenced by the gut microbiota. We longitudinally studied microbiomes from 38 ICI-treated cancer patients. We compared 13 ICI-treated subjects who developed irC against 25 ICI-treated subjects who remained irC-free, along with a validation cohort. Leveraging a preclinical mouse model, predisease stools from irC subjects induced greater colitigenicity upon transfer to mice. The microbiota during the first 10 days of irC closely resembled inflammatory bowel disease microbiomes, with reduced diversity, increased Proteobacteria and Veillonella, and decreased Faecalibacterium, which normalized before irC remission. These findings highlight the irC gut microbiota as functionally distinct but phylogenetically similar to non-irC and healthy microbiomes, with the exception of an acute, transient disruption early in irC. We underscore the significance of longitudinal microbiome profiling in developing clinical avenues to detect, monitor, and mitigate irC in ICI therapy cancer patients.

Gut Microbiota Secondary Metabolites: Key Roles in GI Tract Cancers and Infectious Diseases

The gut microbiota, a dynamic ecosystem of trillions of microorganisms, produces secondary metabolites that profoundly influence host health. Recent research has highlighted the significant role of these metabolites, particularly short-chain fatty acids, indoles, and bile acids, in modulating immune responses, impacting epigenetic mechanisms, and contributing to disease processes. In gastrointestinal (GI) cancers such as colorectal, liver, and gastric cancer, microbial metabolites can drive tumorigenesis by promoting inflammation, DNA damage, and immune evasion. Conversely, these same metabolites hold therapeutic promise, potentially enhancing responses to chemotherapy and immunotherapy and even directly suppressing tumor growth. In addition, gut microbial metabolites play crucial roles in infectious disease susceptibility and resilience, mediating immune pathways that impact pathogen resistance. By consolidating recent insights into the gut microbiota's role in shaping disease and health, this review underscores the therapeutic potential of targeting microbiome-derived metabolites for treating GI cancers and infectious diseases and calls for further research into microbiome-based interventions.

Lower respiratory tract microbiome dysbiosis impairs clinical responses to immune checkpoint blockade in advanced non-small-cell lung cancer

BACKGROUND

Gut microbiome on predicting clinical responses to immune checkpoint inhibitors (ICIs) has been discussed in detail for decades, while microecological features of the lower respiratory tract within advanced non-small-cell lung cancer (NSCLC) are still relatively vague.

METHODS

During this study, 26 bronchoalveolar lavage fluids (BALF) from advanced NSCLC participants who received immune checkpoint inhibitor monotherapy were performed 16S rRNA sequencing and untargeted metabolome sequencing to identify differentially abundant microbes and metabolic characteristics. Additionally, inflammatory cytokines and chemokines were also launched in paired BALF and serum samples by immunoassays to uncover their underlying correlations. The omics data were separately analyzed and integrated by using multiple correlation coefficients. Multiplex immunohistochemical staining was then used to assess the immune cell infiltration after immune checkpoint blockade therapy.

RESULTS

Lower respiratory tract microbiome diversity favoured preferred responses to ICIs. Microbial markers demonstrated microbial diversity overweight a single strain in favoured response to ICI therapy, where Bacillus matters. Sphingomonas and Sediminibacterium were liable to remodulate lipid and essential amino acid degradations to embrace progression after immunotherapies. Microbiome-derived metabolites reshaped the immune microenvironment in the lower respiratory tract by releasing inflammatory cytokines and chemokines, which was partially achieved by metabolite-mediated tumoral inflammatory products and reduction of CD8+ effective T cells and M1 phenotypes macrophages in malignant lesions.

CONCLUSIONS

This study provided a microecological landscape of the lower respiratory tract with advanced NSCLC to ICI interventions and presented a multidimensional perspective with favoured outcomes that may improve the predictive capacity of the localized microbiome in clinical practices.

HIGHLIGHTS

Alterations of the lower respiratory tract microbiome indicate different clinical responses to ICB within advanced NSCLC. Reduced microbial diversity of lower respiratory tracts impairs anti-tumoral performances. Microbe-derived metabolites perform as a dominant regulator to remodify the microecological environment in lower respiratory tracts. Multi-omics sequencings of the lower respiratory tract possess the potential to predict the long-term clinical responses to ICB among advanced NSCLC.

Review: Gut microbiota: Therapeutic targets of ginseng polysaccharides against multiple disorders

As biological macromolecules, ginseng polysaccharides (GP) are often difficult to be directly absorbed through the intestinal cell membrane. It has been found that it can regulate gut microbiota by acting as a prebiotic, and then play a therapeutic role in some diseases, such as diarrhea, tumour, diabetic, dementia, obesity. With the deepening of research, we found that the role played by GP as a prebiotic cannot be ignored. Not only that, it can also affect the immunity and the metabolism and absorption of ginsenosides to play a synergistic role. Overall, GP can regulate the diversity of gut microbiota, which in turn affects the synthesis of secondary metabolites. GP also promotes the transformation of ginsenosides, leading to improved absorptivity of these compounds. This review aims to provide a deeper understanding of how GP interacts with the gut microbiota in various disorders and the transformation of ginsenosides. By exploring these interactions, we can gain valuable insights into the potential benefits of GP in managing different health conditions and enhancing the bioavailability of ginsenosides.

Mechanisms of Anti-PD Therapy Resistance in Digestive System Neoplasms

Digestive system neoplasms are highly heterogeneous and exhibit complex resistance mechanisms that render anti-programmed cell death protein (PD) therapies poorly effective. The tumor microenvironment (TME) plays a pivotal role in tumor development, apart from supplying energy for tumor proliferation and impeding the body's anti-tumor immune response, the TME actively facilitates tumor progression and immune escape via diverse pathways, which include the modulation of heritable gene expression alterations and the intricate interplay with the gut microbiota. In this review, we aim to elucidate the mechanisms underlying drug resistance in digestive tumors, focusing on immune-mediated resistance, microbial crosstalk, metabolism, and epigenetics. We will highlight the unique characteristics of each digestive tumor and emphasize the significance of the tumor immune microenvironment (TIME). Furthermore, we will discuss the current therapeutic strategies that hold promise for combination with cancer immune normalization therapies. This review aims to provide a thorough understanding of the resistance mechanisms in digestive tumors and offer insights into potential therapeutic interventions.

The Oral Microbiome and Cancer

There is growing evidence suggesting a strong association between members of the oral microbiota and various types of cancer, including oral cancer, colorectal cancer, esophageal squamous cell carcinoma, and pancreatic cancer. Periodontal diseases closely associated with pathogenic bacteria in the oral cavity have been shown to be correlated with the occurrence and development of cancers. Among the periodontal disease-associated bacteria in the oral cavity, two prominent oral pathogens, Porphyromonas gingivalis and Fusobacterium nucleatum, have been found to promote tumor cell proliferation, invasion, and migration, as well as to inhibit immune cell function, thereby facilitating tumor progression. The presence of other oral pathogenic bacteria, such as Treponema denticola, Tannerella forsythia, Parvimonas micra, and Aggregatibacter actinomycetemcomitans, has also been found to be associated with cancer worsening. Oral commensal bacteria play a crucial role in maintaining the normal oral homeostasis. However, the relationship between oral commensal bacteria and the occurrence and development of cancers remains controversial. Some studies suggest an increase in oral commensal bacteria during tumor development, while others suggest an association of certain commensal bacteria with lower tumor risk. The microbiota can significantly alter responses and toxicity to various forms of cancer treatment through interactions with the human body, thereby influencing disease progression. In this chapter, we provide a concise overview of current understanding of the role of the oral microbiota in cancer.

Pharma[e]cology: How the Gut Microbiome Contributes to Variations in Drug Response

Drugs represent our first, and sometimes last, line of defense for many diseases, yet despite decades of research we still do not fully understand why a given drug works in one patient and fails in the next. The human gut microbiome is one of the missing puzzle pieces, due to its ability to parallel and extend host pathways for drug metabolism, along with more complex host-microbiome interactions. Herein, we focus on the well-established links between the gut microbiome and drugs for heart disease and cancer, plus emerging data on neurological disease. We highlight the interdisciplinary methods that are available and how they can be used to address major remaining knowledge gaps, including the consequences of microbial drug metabolism for treatment outcomes. Continued progress in this area promises fundamental biological insights into humans and their associated microbial communities and strategies for leveraging the microbiome to improve the practice of medicine.

Lachnoclostridium intestinal flora is associated with immunotherapy efficacy in nasopharyngeal carcinoma

BACKGROUND

Effective biomarkers for assessing anti-PD-1/PD-L1 therapy efficacy in patients with nasopharyngeal carcinoma (NPC) are still lacking. The human gut microbiota has been shown to influence clinical response to anti-PD-1/PD-L1 therapy in many cancers. However, the relationship between the gut microbiota and the efficacy of immunotherapy in patients with nasopharyngeal carcinoma has not been determined.

METHODS

We conducted a prospective study in which fecal and blood samples from patients with NPC were subjected to 16S rDNA sequencing and survival analysis. To investigate potential differences in the gut microbiome between these groups and to identify potential biomarkers indicative of immunotherapy efficacy, patients were categorized into two groups according to their clinical response to immunotherapy, the responder group (R group) and the non-responder group (NR group). Progression-free survival (PFS) between these subgroups was analyzed using Kaplan-Meier survival analysis with the log-rank test. Additionally, we performed univariate and multivariate analyses to evaluate prognostic factors. Finally, we carried out non-targeted metabolomics to examine the metabolic effects associated with the identified microbiome.

RESULTS

Our 16S rDNA sequencing results showed that the abundance of Lachnoclostridium was higher in the NR group than in the R group (p = 0.003), and alpha diversity analysis showed that the abundance of microbiota in the NR group was higher than that in the R group (p = 0.050). Patients with a lower abundance of Lachnoclostridium had better PFS (p = 0.048). Univariate (p = 0.017) and multivariate analysis (p = 0.040) showed that Lachnoclostridium was a predictor of PFS. Non-targeted metabolomics analysis revealed that Lachnoclostridium affects the efficacy of immunotherapy through the usnic acid.

CONCLUSIONS

High abundance of Lachnoclostridium predicts poor prognosis in patients with NPC receiving immunotherapy.

Microbiome and Hemato-immune Aging

The microbiome is a highly complex and diverse symbiotic component that undergoes dynamic changes with the organismal aging. Microbial perturbations, termed dysbiosis, exert strong influence on dysregulating the bone marrow niche and subsequently promoting the aging of hematopoietic and immune system. Accumulating studies have revealed the substantial impact of intestinal microbiome on the initiation and progression of age-related hematologic alteration and diseases, such as clonal hematopoiesis and blood cancers. Current therapeutic approaches to restore the altered microbiome diversity target specific pathobionts and are demonstrated to improve clinical outcomes of antihematologic malignancy treatments. In this review, we discuss the interplay between the microbiome and the hemato-immune system during aging process. We also shed light on the emerging therapeutic strategies to tackle the dysbiosis for amelioration of aging and disease progression.

Engineered Bacteria for Disease Diagnosis and Treatment Using Synthetic Biology

Using synthetic biology techniques, bacteria have been engineered to serve as microrobots for diagnosing diseases and delivering treatments. These engineered bacteria can be used individually or in combination as microbial consortia. The components within these consortia complement each other, enhancing diagnostic accuracy and providing synergistic effects that improve treatment efficacy. The application of microbial therapies in cancer, intestinal diseases, and metabolic disorders underscores their significant potential. The impact of these therapies on the host's native microbiota is crucial, as engineered microbes can modulate and interact with the host's microbial environment, influencing treatment outcomes and overall health. Despite numerous advancements, challenges remain. These include ensuring the long-term survival and safety of bacteria, developing new chassis microbes and gene editing techniques for non-model strains, minimising potential toxicity, and understanding bacterial interactions with the host microbiota. This mini-review examines the current state of engineered bacteria and microbial consortia in disease diagnosis and treatment, highlighting advancements, challenges, and future directions in this promising field.

The Bidirectional Impact of Cancer Radiotherapy and Human Microbiome: Microbiome as Potential Anti-tumor Treatment Efficacy and Toxicity Modulator

Microbiome and radiotherapy represent bidirectionally interacting entities. The human microbiome has emerged as a pivotal modulator of the efficacy and toxicity of radiotherapy; however, a reciprocal effect of radiotherapy on microbiome composition alterations has also been observed. This review explores the relationship between the microbiome and extracranial solid tumors, particularly focusing on the bidirectional impact of radiotherapy on organ-specific microbiome. This article aims to provide a systematic review on the radiotherapy-induced microbial alteration in-field as well as in distant microbiomes. In this review, particular focus is directed to the oral and gut microbiome, its role in the development and progression of cancer, and how it is altered throughout radiotherapy. This review concludes with recommendations for future research, such as exploring microbiome modification to optimize radiotherapy-induced toxicities or enhance its anti-cancer effects.

Treatment of immune checkpoint inhibitor-related colitis: a narrative review

Background and Objective

Cancer is one of the most difficult diseases facing modern medicine, and increasing amounts of research and clinical treatments are being applied to the treatment of cancer. Immunotherapy, particularly immune checkpoint inhibitor (ICI) therapy, has revolutionized the treatment and overall survival of patients with several different types of cancer. Approximately one-third of patients treated with ICIs may experience immune-related adverse events (irAEs). Immune checkpoint inhibitor-associated colitis (ICIC) is the most common irAE with an incidence of approximately 8-10%, ICIC usually presents as watery or bloody diarrhea, and if the symptoms are severe, ICI treatment must be interrupted or even terminated. This review summarizes the epidemiology, pathogenesis, clinical characteristics, and therapies of ICIC, focusing on the use of biologics, in order to propose treatment options in different situations to control immune checkpoint inhibitor-related colitis as soon as possible.

Methods

To find relevant articles for this narrative review paper, a combination of keywords such as immune checkpoint inhibitor-related colitis, corticosteroids, biologics were searched for in PubMed databases.

Key Content and Findings

The pathogenesis of ICIC is complex and primarily involves antitumor effects and indirect damage to colonic tissues, as well as the activation of specific proinflammatory pathways. Corticosteroids (CSs) are the first line of treatment for ICIC, but steroid-refractory or steroid-resistant cases often occur. Patients with irAE colitis respond favorably to biologics, and patients with CS-resistant/refractory enterocolitis can benefit from the early use of biologics.

Conclusions

Biologics are currently recommended for the treatment of ICIC but are usually used as a supplement after the failure of first-line CS therapy. Patients with irAE colitis respond favorably to biologics, and patients with CS-resistant/refractory enterocolitis can benefit from the early use of biologics. Biologics (alone or in combination with CS) should be considered as an early therapy option for high-risk patients rather than just an escalation after a failure to respond to CS.

Predictive biomarkers for immune checkpoint inhibitors therapy in lung cancer

Immune checkpoint inhibitors (ICIs) have changed the treatment mode of lung cancer, extending the survival time of patients unprecedentedly. Once patients respond to ICIs, the median duration of response is usually longer than that achieved with cytotoxic or targeted drugs. Unfortunately, there is still a large proportion of lung cancer patients do not respond to ICI. Effective biomarkers are crucial for identifying lung cancer patients who can benefit from them. The first predictive biomarker is programmed death-ligand 1 (PD-L1), but its predictive value is limited to specific populations. With the development of single-cell sequencing and spatial imaging technologies, as well as the use of deep learning and artificial intelligence, the identification of predictive biomarkers has been greatly expanded. In this review, we will dissect the biomarkers used to predict ICIs efficacy in lung cancer from the tumor-immune microenvironment and host perspectives, and describe cutting-edge technologies to further identify biomarkers.

The trends and hotspots of immunotherapy for metastatic colorectal cancer from 2013 to 2022: A bibliometric and visual analysis

An increasing body of research indicates that immunotherapy has demonstrated substantial effectiveness in the realm of metastatic colorectal cancer(mCRC), especially among patients with deficient mismatch repair (dMMR) or microsatellite instability-high (MSI-H) (dMMR/MSI-H mCRC). This study constitutes the inaugural bibliometric and visual analysis of immunotherapy related to mCRC during the last decade. Between 2013 and the conclusion of 2022, we screened 306 articles from Web of Science and subjected them to analysis using CiteSpace and VOSviewer. The United States stood out as the primary contributor in this area, representing 33.33% of the publications, with China following closely at 24.51%. The most prolific institution has the lowest average citation rate. Sorbonne University were the most highly cited institutions. Notably, Frontiers In Oncology published the largest quantity of articles. Andre, Thierry, and Overman, Michael J. were prominent authors known for their prolific output and the high citation rates of their work. The focus areas in this field encompass "tumor microenvironment," "liver metastasis," "tumor-associated macrophages," "combination therapy" and "gut microbiota." Some keywords offer promise as potential biomarkers for evaluating the effectiveness of immunotherapeutic interventions.

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.

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.

Gut microbiota in cancer initiation, development and therapy

Cancer has long been associated with genetic and environmental factors, but recent studies reveal the important role of gut microbiota in its initiation and progression. Around 13% of cancers are linked to infectious agents, highlighting the need to identify the specific microorganisms involved. Gut microbiota can either promote or inhibit cancer growth by influencing oncogenic signaling pathways and altering immune responses. Dysbiosis can lead to cancer, while certain probiotics and their metabolites may help reestablish micro-ecological balance and improve anti-tumor immune responses. Research into targeted approaches that enhance therapy with probiotics is promising. However, the effects of probiotics in humans are complex and not yet fully understood. Additionally, methods to counteract harmful bacteria are still in development. Early clinical trials also indicate that modifying gut microbiota may help manage side effects of cancer treatments. Ongoing research is crucial to understand better how gut microbiota can be used to improve cancer prevention and treatment outcomes.

The influence of microbiota on the efficacy and toxicity of immunotherapy in cancer treatment

Immunotherapy, which uses the body's immune system to fight cancer cells, has gained attention recently as a breakthrough in cancer treatment. Although significant progress has been made, obstacles still exist since cancers are skilled at avoiding immune monitoring. The gut microbiota is being looked at more and more in modern research as a critical component in improving the results of immunotherapy. Through modulating both innate and adaptive immune responses, the gut microbiome has a significant impact on cancer immunotherapy. The effectiveness of treatment and the way the immune system responds are significantly influenced by some microorganisms and the metabolites they produce, especially short-chain fatty acids. On the other hand, dysbiosis and persistent inflammation in the gut environment might unintentionally accelerate the growth of tumors, which makes the complex relationship between the makeup of the microbiota and cancer treatment more challenging. Gut microbiota plays a crucial role in immunotherapy effectiveness. Improved microbial diversity leads to better treatment responses, with some taxa like Bacteroides and Ruminococcaceae being linked to better responses to immune checkpoint inhibitors. Dysbiotic conditions can worsen immune-related side effects and reduce treatment effectiveness. Strategies manipulating gut microbiota, such as fecal microbiota transplantation, antibiotic therapies, and dietary interventions, could optimize immunotherapy response and prognosis. However, standardizing these interventions for different cancer types and patient populations is challenging due to individual microbiome differences. Future research should combine microbiome research with AI and rigorous clinical trials for individualized cancer treatments.

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.

Molecular module for glucose production influences sex pheromone synthesis in Bactrocera dorsalis

Some insects have evolved beneficial relationships with intestinal microbes for sex pheromone production to communicate with conspecifics effectively. However, it is not clear whether the sex pheromone synthesis activity of intestinal microbes can be controlled by the host, and the molecular mechanisms need to be further unraveled. In this study, we find that rectal gland Bacillus species of male Bactrocera dorsalis specifically produce sex pheromones in the evening, which is significantly associated with glucose levels. In vitro Bacillus culture assays show that glucose levels significantly influence the amount of sex pheromone produced. Comparative rectal gland transcriptome analysis reveals that the expressions of the alpha-galactosidase gene (GLA), a Bactrocera dorsalis transcription factor (BDTF), and a pigment-dispersing factor (PDF) are responsible for producing glucose. Our findings reveal that the PDF-BDTF-GLA module influences the intestinal-microbe-produced sex pheromone by regulating glucose levels and advance our understanding of interactions between insects and their intestinal microbes.

Bacteroides fragilis capsular polysaccharide A ameliorates ulcerative colitis in rat by recovering intestinal barrier integrity and restoring gut microbiota

Bacteroides fragilis (B. fragilis) is a Gram-negative, obligate anaerobic, commensal bacterium residing in the human gut and holds therapeutic potential for ulcerative colitis (UC). Previous studies have indicated that capsular polysaccharide A (PSA) of B. fragilis is a crucial component for its effectiveness, possessing various biological activities such as anti-inflammatory, anti-tumor, and immune-modulating effects. We previously isolated and characterized the B. fragilis strain ZY-312 from the feces of a healthy breastfed infant, and extracted its PSA, named TP2. In this study, we explored the impact of TP2 on colonic inflammation and delved into its potential mechanisms. Initially, we used 2,4,6-trinitrobenzenesulfonic acid (TNBS) to induce colitis in rats and found that TP2 treatment significantly ameliorated TNBS-induced weight loss, increased clinical scores, extensive ulcers, and intestinal epithelial damage in UC rats. Further analysis revealed that TP2 effectively restored the intestinal barrier integrity in UC rats by regulating the expression of Muc-2, tight junction proteins (ZO-1, occludin, claudin-1, and claudin-2), as well as apoptosis-related proteins Bcl-2, BAX, and Cleaved-Caspase-3. Additionally, TP2 suppressed the expression of pro-inflammatory cytokines TNF-α, IL-1β, IL-6, and IL23, while promoting the secretion of anti-inflammatory cytokines IL-10 and IL-22, thereby inhibiting the occurrence of inflammation. TP2 also downregulated the phosphorylation levels of AKT and PI3K, effectively inhibiting the abnormal activation of the PI3K/AKT signaling pathway. More interestingly, 16S rRNA sequencing results showed that TP2 restored the ecological imbalance of the rat intestinal microbiota, with an increase in beneficial bacteria such as Lactobacillus and Limosilactobacillus observed in the treatment group. In conclusion, TP2 through the regulation of intestinal barrier-related cells and proteins, inhibition of apoptosis, modulation of inflammation-related cytokine levels, and control of abnormal activation of the PI3K/AKT signaling pathway, restores intestinal barrier integrity. Additionally, by reshaping the ecological imbalance of the gut microbiota, TP2 ultimately alleviates ulcerative colitis in rats.

Impact of Tobacco, Marijuana, and Alcohol Use on Overall Survival in Recurrent Metastatic Head and Neck Cancer Patients Treated With Immune Checkpoint Inhibitors

AIM

The response rates to immune checkpoint inhibitors (ICI) remain low (13%-20%) in metastatic head and neck cancer patients, indicating an urgent need to better understand factors predictive of response to these agents. This study explored the impact of smoking status, marijuana use, and alcohol consumption on treatment outcomes in recurrent-metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) patients treated with ICI.

METHODS

A retrospective analysis was performed on 201 R/M HNSCC patients treated with ICI between January 15th 2016 and April 9th 2020 at a single institution.

RESULTS

Gender: 154 male (77%), 47 female (23%). Median age 61 (IQR: 55-68). ICI drug: pembrolizumab 100 (50%), nivolumab 91 (45%), nivolumab + ipilimumab 10 (5%). Line of therapy: first: 98 (49%), second and beyond: 103 (51%). Tumor site: oropharynx 84 (42%), oral cavity 45 (22%), larynx 26 (13%), other sites 46 (23%). p16 tumor status: negative 132 (66%), positive 69 (34%). Smoking status: former 111 (55%), never 54 (27%), current 36 (18%), median pack-year 18 (IQR: 0-37). Alcohol use: yes 110 (55%), no 91 (54%). Marijuana use: yes 47 (23%), no 154 (77%). Overall response rate: 36 (18%). Median OS: 12 months (95% CI: 9.4-14.8). Tobacco: former (HR: 0.75, 95% CI: 0.50, 1.11), current (HR: 0.58, 95% CI: 0.33, 1.02). Marijuana: yes (HR: 0.93, 95% CI: 0.58, 1.49). Alcohol: yes (HR: 1.04, 95% CI: 0.72, 1.49).

CONCLUSION

In our cohort, smoking status, marijuana use, and alcohol consumption did not have a statistically significant impact on OS in patients with R/M HNSCC treated with ICI.

Curcumin-Modified Selenium Nanoparticles Improve S180 Tumour Therapy in Mice by Regulating the Gut Microbiota and Chemotherapy

Purpose

This study aimed to synthesize curcumin-modified selenium (Cur/Se) nanoparticles via a simple and green method for tumour treatment and explore their effects on the gut microbiota.

Methods

Curcumin was applied as a reducing and capping agent for the construction of Cur/Se nanoparticles with Tween 80 as a stabilizer. The drug release behaviour and DPPH and ABTS radical scavenging activities of the Cur/Se nanoparticles were detected. MTT and CCK8 assays were used to evaluate the cytotoxicity against HeLa and S180 tumour cells. The cellular distribution, uptake and reactive oxygen species (ROS) levels were detected. In vivo anti-S180 tumour activity was studied by oral administration. 16S rRNA Illumina high-throughput sequencing technology was used to analyse the gut microbiota in ileocecal faeces.

Results

Nanoparticles with good water dispersibility and a size of 6.86 nm were obtained. The characteristic peaks of curcumin were observed in the UV and FTIR spectra of the Cur/Se nanoparticles. Curcumin release from the Cur/Se nanoparticles occurred in a pH-dependent and sustained manner at 48 h. The Cur/Se nanoparticles presented significantly higher DPPH and ABTS radical scavenging rates than the same concentration of free curcumin. At 48 h, the Cur/Se nanoparticles showed higher cytotoxicity against HeLa and S180 tumour cells. The results of the cellular uptake experiments revealed that the Cur/Se nanoparticles significantly delivered more curcumin into the HeLa tumour cells and induced greater ROS production. In vivo, the Cur/Se nanoparticles significantly inhibited S180 tumours, with a 54.33% tumour inhibitory rate. Cur and Cur/Se nanoparticles significantly reduced the relative abundances of Rikenellaceae_RC9_gut_group, Enterorhabdus and Bilophila and increased the relative abundance of Lachnospiraceae_UCG-006. Moreover, Cur/Se nanoparticle treatment significantly improved the relative abundance of Limosilactobacillus compared with that in the curcumin group.

Conclusion

Cur/Se nanoparticles could increase the bioactivity of curcumin and improve cancer therapy by regulating the gut microbiota.

Biomarkers for immunotherapy resistance in non-small cell lung cancer

Immunotherapy has revolutionised the treatment landscape of non-small cell lung cancer (NSCLC), significantly improving survival outcomes and offering renewed hope to patients with advanced disease. However, the majority of patients experience limited long-term benefits from immune checkpoint inhibition (ICI) due to the development of primary or acquired immunotherapy resistance. Accurate predictive biomarkers for immunotherapy resistance are essential for individualising treatment strategies, improving survival outcomes, and minimising potential treatment-related harm. This review discusses the mechanisms underlying resistance to immunotherapy, addressing both cancer cell-intrinsic and cancer cell-extrinsic resistance processes. We summarise the current utility and limitations of two clinically established biomarkers: programmed death ligand 1 (PD-L1) expression and tumour mutational burden (TMB). Following this, we present a comprehensive review of emerging immunotherapy biomarkers in NSCLC, including tumour neoantigens, epigenetic signatures, markers of the tumour microenvironment (TME), genomic alterations, host-microbiome composition, and circulating biomarkers. The potential clinical applications of these biomarkers, along with novel approaches to their biomarker identification and targeting, are discussed. Additionally, we explore current strategies to overcome immunotherapy resistance and propose incorporating predictive biomarkers into an adaptive clinical trial design, where specific immune signatures guide subsequent treatment selection.

Research Progress on the Relationship Between Artificial Sweeteners and Breast Cancer

Artificial sweeteners, as low-calorie sugar substitutes, have attracted much attention in recent years, especially in terms of their potential health effects. Although they add almost no calories, studies have shown that artificial sweeteners may affect metabolism by stimulating insulin secretion and changing the intestinal microbiota, increasing the risk of metabolic syndrome and type 2 diabetes. Breast cancer, as the most common cancer in the world, is related to multiple factors such as genetics and hormone levels. The results of studies on artificial sweeteners and breast cancer risk are conflicting, with some showing a positive correlation between the two and others failing to confirm it. Differences in study design, participant characteristics, and the types of sweeteners have led to this ambiguity. Although some studies have focused on mechanisms such as hormone disorders, insulin response, and changes in the intestinal microbiota, further exploration is needed to establish a causal relationship. Our review aims to comprehensively analyze the potential association between artificial sweeteners and breast cancer and its mechanisms, as well as encourage future studies to reveal its long-term health effects.

Synergy between Lactobacillus murinus and anti-PcrV antibody delivered in the airways to boost protection against Pseudomonas aeruginosa

Therapeutic antibodies (Ab) have revolutionized the management of multiple illnesses including respiratory tract infections (RTIs). However, anti-infectious Ab displayed several limitations including antigen restrictiveness, narrowed therapeutic windows, and limited dose in the vicinity of the target when delivered by parenteral routes. Strategies enhancing further Ab-dependent containment of infection are currently needed. Here we showed that a combination of inhaled anti-infectious Ab and probiotics is an efficient formulation to protect against lung infection. Using a mouse model of Pseudomonas aeruginosa-induced pneumonia, we demonstrated a synergistic effect reducing both bacterial burden and pro-inflammatory response affording protection against primary and secondary infections. This is the first study showing that the local combination in the airways of anti-infective Ab and probiotics subverts suboptimal potency of Ab monotherapy and provides protection against respiratory pathogen.

Discover Mutational Differences Between Lung Adenocarcinoma and Lung Squamous Cell Carcinoma and Search for More Effective Biomarkers for Immunotherapy

Purpose

Lung cancer is a severe malignant tumor. This study aims to more comprehensively characterize lung cancer patients and identify combination markers for immunotherapy.

Patients and Methods

We gathered data from 166 lung cancer patients at the Cancer Hospital Affiliated with Xinjiang Medical University. The collected samples underwent NGS sequencing using a panel of 616 genes associated with cancer. Subsequently, data analysis was conducted to identify markers that are more suitable for lung cancer immunotherapy.

Results

In this study, the most common variant genes in LUAD were TP53, EGFR, MST1, KMT2C, RBM10, LRP1B. Meanwhile, the highest mutation frequency genes in LUSC samples were TP53, KMT2D, LRP1B, FAT1, MST1, KMT2C. Mutation frequencies, tumor mutation burden (TMB), PD-L1 expression, and mutant-allele tumor heterogeneity (MATH) values differed between LUAD and LUSC, with LUSC exhibiting higher values than LUAD. Irrespective of LUAD or LUSC, patients with TMB≥10 demonstrated better immunotherapy efficacy compared to patients with TMB<10. Similarly, when PD-L1≥50%, whether in LUAD or LUSC, the immunotherapy effect was superior to that of patients with PD-L1<50%. Combining TMB≥10 and PD-L1≥50% as immunotherapy markers, in both LUAD and LUSC, resulted in a very favorable immunotherapy effect, with the overall response rate (ORR) reaching 100%.

Conclusion

We observed distinct mutation patterns and clinical factors between LUAD and LUSC, and noted that patients with TMB≥10 and PD-L1≥50% exhibited enhanced immunotherapy effects. Combining TMB≥10 and PD-L1≥50% proved to be a more effective predictor of immunotherapy efficacy.

Microbiota and Cytokine Modulation: Innovations in Enhancing Anticancer Immunity and Personalized Cancer Therapies

The gut microbiota plays a crucial role in modulating anticancer immunity, significantly impacting the effectiveness of various cancer therapies, including immunotherapy, chemotherapy, and radiotherapy. Its impact on the development of cancer is complex; certain bacteria, like Fusobacterium nucleatum and Bacteroides fragilis, can stimulate the growth of tumors by causing immunological evasion and inflammation, while advantageous strains, like Faecalibaculum rodentium, have the ability to suppress tumors by modifying immune responses. Cytokine activity and immune system regulation are intimately related. Cytokines including TGF-β, IL-6, and IL-10 promote tumor development by inhibiting efficient immune surveillance. The gut microbiome exhibits a delicate balance between pro- and anti-tumorigenic factors, as evidenced by the enhancement of anti-tumor immunity by cytokines such as IL-12 and IFN-γ. Improved immunotherapy responses are linked to a diverse microbiota, which is correlated with higher tumor infiltration and cytotoxic T-cell activation. Because microbial metabolites, especially short-chain fatty acids, affect cytokine expression and immune cell activation inside the tumor microenvironment, this link highlights the need to maintain microbial balance for optimal treatment effects. Additionally, through stimulating T-cell activation, bacteria like Lactobacillus rhamnosus and Bifidobacterium bifidum increase cytokine production and improve the efficacy of immune checkpoint inhibitors (ICIs). An option for overcoming ICI resistance is fecal microbiota transplantation (FMT), since research suggests that it improves melanoma outcomes by increasing CD8+ T-cell activation. This complex interaction provides an opportunity for novel cancer therapies by highlighting the possibility of microbiome modification as a therapeutic approach in personalized oncology approaches.

Causality between gut microbiota, immune cells, and breast cancer: Mendelian randomization analysis

The association between gut microbiota (GM) and breast cancer (BC) has been studied. Nevertheless, the causal relationship between them and the potential mediating factors have not been clearly defined. Therefore, in this study, Mendelian randomization analysis (MR) was employed to explore the causal relationship between 473 GM and BC, as well as the mediating effect of potential immune cells. In this investigation, we availed ourselves of the publicly accessible summary statistics from the genome-wide association study to undertake two-sample and reverse Mendelian randomization analyses on GM and BC, with the intention of clarifying the causal association between GM and BC. Subsequently, through the application of the two-step Mendelian randomization analysis, it was revealed that the relationship between GM and BC was mediated by immune cells. The stability of the research outcomes was verified via sensitivity analysis. Mendelian randomization analysis elucidated the protective impacts of 8 genera on BC (such as Phylum Actinobacteriota, Species Bacteroides A plebeius A, Species Bifidobacterium adolescentis, Species CAG-841 sp002479075, Family Fibrobacteraceae, Order Fibrobacterales, Class Fibrobacteria, and Species Phascolarctobacterium sp003150755). Additionally, there are 23 immune cell traits related to BC. Our research findings showed that the species Megamonas funiformis was associated with an increased risk of BC, and 11.20% of this effect was mediated by CD38 on IgD+ CD24-. Likewise, HLA DR on CD33br HLA DR+ CD14- mediated the causal relationship between Species Prevotellamassilia and BC, having a mediating ratio of 7.89%. This study clarifies a potential causal relationship between GM, immune cells, and BC and provides genetic evidence for this causal connection. It offers research directions for the subsequent prevention and treatment of BC through the interaction between GM and immune cells, and provides a reference for future mechanistic and clinical studies in this field.

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 effect of immunotherapy PD-1 blockade on acute bone cancer pain: Insights from transcriptomic and microbiomic profiling

INTRODUCTION

The skeletal system ranks as the third most common site for cancer metastasis, often leading to pain with nociceptive and neuropathic features. Programmed cell death protein 1 (PD-1)-targeting therapeutic antibodies offer effective cancer treatment but can cause treatment-related acute pain. Understanding the mechanisms of this pain and identifying potential interventions is still a challenge.

METHODS

A murine model of bone cancer pain was established using Lewis lung carcinoma (LLC) cells, followed by intravenous administration of nivolumab, a human anti-PD-1 monoclonal antibody. Pain thresholds were measured, and micro-CT images of the skeletal system were obtained. High-throughput sequencing of the spinal cord/colon transcriptome during the acute phase of bone cancer pain and gut microbiota analysis at the end of the treatment were performed. Immunofluorescence staining and western blot experiments assessed spinal cord microglia activation and acute pain-associated molecules.

RESULTS

PD-1 inhibition with nivolumab protected against bone degradation initiated by LLC cell administration but consistently induced acute pain during nivolumab treatment. Spinal cord and colon transcriptomics revealed an immunopathological pattern during tumor progression and the acute pain phase, with notable changes in interleukin and S100 gene families. Gut microbiota analysis post-immunotherapy showed a decline in beneficial bacteria associated with short-chain fatty acid (SCFA) production. Activation of spinal cord microglia and enhanced glycolytic metabolism were confirmed as key factors in inducing acute pain following immunotherapy.

CONCLUSIONS

This study reveals that nivolumab induces acute pain by activating microglia and enhancing glycolytic metabolism in the treatment of bone cancer and uncovers connections between transcriptomic changes, gut microbiota, and acute pain following immune checkpoint blockade (ICB) treatment. It offers novel insights into the relationship between immune checkpoint blockade therapies and pain management.

Diet and Immune Effects Trial (DIET)- a randomized, double-blinded dietary intervention study in patients with melanoma receiving immunotherapy

BACKGROUND

Gut microbiome modulation is a promising strategy for enhancing the response to immune checkpoint blockade (ICB). Fecal microbiota transplant studies have shown positive signals of improved outcomes in both ICB-naïve and refractory melanoma patients; however, this strategy is challenging to scale. Diet is a key determinant of the gut microbiota, and we have previously shown that (a) habitual high dietary fiber intake is associated with an improved response to ICB and (b) fiber manipulation in mice impacts antitumor immunity. We recently demonstrated the feasibility of a controlled high-fiber dietary intervention (HFDI) conducted in melanoma survivors with excellent compliance and tolerance. Building on this, we are now conducting a phase II randomized trial of HFDI versus a healthy control diet in melanoma patients receiving ICB.

METHODS

This is a randomized, double-blind, fully controlled feeding study that will enroll 45 melanoma patients starting standard-of-care (SOC) ICB in three settings: adjuvant, neoadjuvant, and unresectable. Patients are randomized 2:1 to the HFDI (target fiber 50 g/day from whole foods) or healthy control diet (target fiber 20 g/day) stratified by BMI and cohort. All meals are prepared by the MD Anderson Bionutrition Core and are isocaloric and macronutrient-controlled. The intervention includes a 1-week equilibration period and then up to 11 weeks of diet intervention. Longitudinal blood, stool and tumor tissue (if available) are collected throughout the trial and at 12 weeks post intervention.

DISCUSSION

This DIET study is the first fully controlled feeding study among cancer patients who are actively receiving immunotherapy. The goal of the current study is to establish the effects of dietary intervention on the structure and function of the gut microbiome in patients with melanoma treated with SOC immunotherapies. The secondary endpoints include changes in systemic and tumor immunity, changes in the metabolic profile, quality of life, symptoms, disease response and immunotherapy toxicity.

TRIAL REGISTRATION

This protocol is registered with the U.S. National Institutes of Health trial registry, ClinicalTrials.gov, under the identifier NCT04645680. First posted 2020-11-27; last verified 2024-06.

Role of gut microbiota in tumorigenesis and antitumoral therapies: an updated review

Gut microbiota plays a prominent role in regulation of host nutrientmetabolism, drug and xenobiotics metabolism, immunomodulation and defense against pathogens. It synthesizes numerous metabolites thatmaintain the homeostasis of host. Any disbalance in the normalmicrobiota of gut can lead to pathological conditions includinginflammation and tumorigenesis. In the past few decades, theimportance of gut microbiota and its implication in various diseases, including cancer has been a prime focus in the field of research. Itplays a dual role in tumorigenesis, where it can accelerate as wellas inhibit the process. Various evidences validate the effects of gutmicrobiota in development and progression of malignancies, wheremanipulation of gut microbiota by probiotics, prebiotics, dietarymodifications and faecal microbiota transfer play a significant role.In this review, we focus on the current understanding of theinterrelationship between gut microbiota, immune system and cancer,the mechanisms by which they play dual role in promotion andinhibition of tumorigenesis. We have also discussed the role ofcertain bacteria with probiotic characteristics which can be used tomodulate the outcome of the various anti-cancer therapies under theinfluence of the alteration in the composition of gut microbiota.Future research primarily focusing on the microbiota as a communitywhich affect and modulate the treatment for cancer would benoteworthy in the field of oncology. This necessitates acomprehensive knowledge of the roles of individual as well asconsortium of microbiota in relation to physiology and response ofthe host.

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).

Beyond Tumor Borders: Intratumoral Microbiome Effects on Tumor Behavior and Therapeutic Responses

The human body contains a diverse array of microorganisms, which exert a significant impact on various physiological processes, including immunity, and can significantly influence susceptibility to various diseases such as cancer. Recent advancements in metagenomic sequencing have uncovered the role of intratumoral microbiome, which covertly altered the development of cancer, the growth of tumors, and the response to existing treatments through multiple mechanisms. These mechanisms involve mainly DNA damage induction, oncogenic signaling pathway activation, and the host's immune response modulation. To explore novel therapeutic options and effectively target and regulate the intratumoral microbiome, a comprehensive understanding of these processes is indispensable. Here, we will explore various potential actions of the intratumoral microbiome concerning the initiation and progression of tumors. We will examine its impact on responses to chemotherapy, radiotherapy, and immunotherapy. Additionally, we will discuss the current state of knowledge regarding the use of genetically modified bacteria as a promising treatment option for cancer.

Gut microbiota and healthy longevity

Recent progress on the underlying biological mechanisms of healthy longevity has propelled the field from elucidating genetic modification of healthy longevity hallmarks to defining mechanisms of gut microbiota influencing it. Importantly, the role of gut microbiota in the healthy longevity of the host may provide unprecedented opportunities to decipher the plasticity of lifespan on a natural evolutionary scale and shed light on using microbiota-targeted strategies to promote healthy aging and combat age-related diseases. This review investigates how gut microbiota affects healthy longevity, focusing on the mechanisms through which gut microbiota modulates it. Specifically, we focused on the ability of gut microbiota to enhance the intestinal barrier integrity, provide protection from inflammaging, ameliorate nutrientsensing pathways, optimize mitochondrial function, and improve defense against age-related diseases, thus participating in enhancing longevity and healthspan.

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.

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.