A microbiota-modulated checkpoint directs immunosuppressive intestinal T cells into cancers

Role of gut microbiome in suppression of cancers

The pathogenesis of cancer is closely related to the disruption of homeostasis in the human body. The gut microbiome plays crucial roles in maintaining the homeostasis of its host throughout lifespan. In recent years, a large number of studies have shown that dysbiosis of the gut microbiome is involved in the entire process of cancer initiation, development, and prognosis by influencing the host immune system and metabolism. Some specific intestinal bacteria promote the occurrence and development of cancers under certain conditions. Conversely, some other specific intestinal bacteria suppress the oncogenesis and progression of cancers, including inhibiting the occurrence of cancers, delaying the progression of cancers and boosting the therapeutic effect on cancers. The promoting effects of the gut microbiome on cancers have been comprehensively discussed in the previous review. This article will review the latest advances in the roles and mechanisms of gut microbiome in cancer suppression, providing a new perspective for developing strategies of cancer prevention and treatment.

Surrogate markers of intestinal dysfunction associated with survival in advanced cancers

Deviations in the diversity and composition of the gut microbiota are called "gut dysbiosis". They have been linked to various chronic diseases including cancers and resistance to immunotherapy. Stool shotgun based-metagenomics informs on the ecological composition of the gut microbiota and the prevalence of homeostatic bacteria such as Akkermansia muciniphila (Akk), while determination of the serum addressin MAdCAM-1 instructs on endothelial gut barrier dysfunction. Here we examined patient survival during chemo-immuno-therapy in 955 cancer patients across four independent cohorts of non-small cell lung (NSCLC), genitourinary (GU) and colorectal (CRC) cancers, according to hallmarks of gut dysbiosis. We show that Akk prevalence represents a stable and favorable phenotype in NSCLC and CRC cancer patients. Over-dominance of Akk above the healthy threshold was observed in dismal prognosis in NSCLC and GU and mirrored an immunosuppressive gut ecosystem and excessive intestinal epithelial exfoliation in NSCLC. In CRC, the combination of a lack of Akk and low sMAdCAM-1 levels identified a subset comprising 28% of patients with reduced survival, independent of the immunoscore. We conclude that gut dysbiosis hallmarks deserve integration within the diagnosis toolbox in oncological practice.

New insight into intestinal toxicity accelerated by aged microplastics with triclosan: Inflammation regulation by gut microbiota-bile acid axis

The combined toxic effects of microplastics (MPs) and their carried contaminants on organisms have been widely concerned; however, the health risks and its mechanism of "gut microbiota-host metabolism (bile acids, BA)" remain unknown. Herein, Xenopus tropicalis were exposured to aged polystyrene MPs carried triclosan (aPS+TCS) and single (a)PS-MPs & TCS, respectively. The bioaccumulation of TCS in the gut of X. tropicalis was significantly increased in aPS+TCS group, which was 89 % higher than that of PS+TCS group, causing more severe oxidative stress, inflammation and intestinal barrier disruption (leaky gut). The expressions of TNF-α, IL-6 and IL-10 in aPS+TCS group were enhanced by 276 % and 19 % and decreased by 81 %, respectively, compared to that in PS+TCS group. Moreover, co-exposure to aPS+TCS increased the number of Escherichia coli, and reduced levels of DCA and LCA (secondary BAs). Multiomics analysis further revealed that the intestinal toxicity of aPS+TCS to X. tropicalis was mainly influenced by the gut flora, BA metabolism and inflammation-related pathways. Co-exposure may exacerbate inflammation by increasing the blood levels of lipopolysaccharides and inhibiting secondary BA production, which are regulated by the gut microbiota-bile acid axis. This study provides new insights in the potential mechanisms of intestinal damage from pollutant-loaded aged MPs.

Microbiota-centered interventions to boost immune checkpoint blockade therapies

Immune checkpoint blockade therapies have markedly advanced cancer treatment by invigorating antitumor immunity and extending patient survival. However, therapeutic resistance and immune-related toxicities remain major concerns. Emerging evidence indicates that microbial dysbiosis diminishes therapeutic response rates, while a diverse gut ecology and key beneficial taxa correlate with improved treatment outcomes. Therefore, there is a growing understanding that manipulating the gut microbiota could boost therapy efficacy. This review examines burgeoning methods that target the gut microbiome to optimize therapy and innovative diagnostic tools to detect dysbiosis, and highlights challenges that remain to be addressed in the field.

Gut Microbiota in Immuno-Oncology: A Practical Guide for Medical Oncologists With a Focus on Antibiotics Stewardship

The gut microbiota has emerged as a critical determinant of immune checkpoint inhibitor (ICI) efficacy, resistance, and toxicity. Retrospective and prospective studies profiling the taxonomic composition of intestinal microbes of patients treated with ICI have revealed specific gut microbial signatures associated with response. By contrast, dysbiosis, which can be caused by chronic inflammatory processes (such as cancer) or comedications, is a risk factor of resistance to ICI. Recent large-scale meta-analyses have confirmed that antibiotic (ATB) use before or during ICI therapy alters the microbiota repertoire and significantly shortens overall survival, even after adjusting for prognostic factors. These results underscore the importance of implementing ATB stewardship recommendations in routine oncology practice. Microbiota-centered interventions are now being explored to treat gut dysbiosis and optimize ICI responses. Early-phase clinical trials evaluating fecal microbiota transplantation (FMT) from ICI responders or healthy donors have shown that this approach is safe and provided preliminary data on potential efficacy to overcome both primary and secondary resistance to ICI in melanoma, non-small cell lung cancer, and renal cell carcinoma. More targeted interventions including live bacterial products including Clostridium butyricum and Akkermansia massiliensis represent novel microbiome-based adjunct therapies. Likewise, dietary interventions, such as high-fiber diets, have shown promise in enhancing ICI activity. In this ASCO Educational Book, we summarize the current state-of-the-evidence of the clinical relevance of the intestinal microbiota in cancer immunotherapy and provide a practical guide for ATB stewardship.

Intestinal Microbiome Modulation of Therapeutic Efficacy of Cancer Immunotherapy

Bacteria are associated with certain cancers and may induce genetic instability and cancer progression. The gut microbiome modulates the response to cancer therapy. Training machine learning models with response associated taxa or bacterial genes predict patients' response to immunotherapies with moderate accuracy. Clinical trials targeting the gut microbiome to improve immunotherapy efficacy have been conducted. While single bacterial strains or small consortia have not be reported yet to be successful, encouraging results have been reported in small single arm and randomized studies using transplant of fecal microbiome from cancer patients who successfully responded to therapy or from healthy volunteers.

The interplay between gut microbiota, antibiotics, and immune checkpoint inhibitors in patients with cancer: A narrative review with biological and clinical aspects

Immune checkpoint inhibitors (ICIs) targeting the programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), and cytotoxic T-lymphocyte antigen 4 (CTLA-4) pathways have revolutionized cancer therapy. However, primary and secondary resistance to ICI pose significant challenges. Recent studies underscore the critical role of gut microbiota (GM) in modulating ICI efficacy by shaping host immune responses and regulating the tumor microenvironment (TME). The composition of the GM has been linked to ICI treatment outcomes, with certain microbial taxa, such as Faecalibacterium spp., Bifidobacterium spp., Eubacterium spp., Roseburia spp., and Akkermansia muciniphila, associated with favorable responses. Mechanistically, the GM affects immune responses via multiple pathways, including induction of T cell differentiation, promotion of anti- or proinflammatory cytokine environments, and enhancement of T cell priming and effector functions. Moreover, microbial-derived metabolites play a role in shaping tumor immune responses and influencing ICI efficacy. Antibiotic treatment can disrupt GM diversity and composition (gut dysbiosis), potentially diminishing ICI effectiveness. A deeper understanding of the interplay between GM, antibiotic treatment, and ICI efficacy is crucial for developing personalized therapeutic strategies to improve patient outcomes. Herein, we review current evidence on the association between specific microbial taxa and tumor immunosurveillance, the impact of antibiotics on the GM composition and immune modulation, and its implications for ICI therapy efficacy.

Microbiota mechanisms in cancer progression and therapy

The composition of the microbiota in patients has been shown to correlate with cancer progression and response to therapy, highlighting unique opportunities to improve patient outcomes. In this review, we discuss the challenges and advancements in understanding the chemical mechanisms of specific microbiota species, pathways, and molecules involved in cancer progression and treatment. We also describe the modulation of cancer and immunotherapy by the microbiota, along with approaches for investigating microbiota enzymes and metabolites. Elucidating these specific microbiota mechanisms and molecules should offer new opportunities for developing enhanced diagnostics and therapeutics to improve outcomes for cancer patients. Nonetheless, many microbiota mechanisms remain to be determined and require innovative chemical genetic approaches.

Roles of the gut microbiota in immune-related adverse events: mechanisms and therapeutic intervention

Immune checkpoint inhibitors (ICIs) constitute a major breakthrough in the field of cancer therapy; their use has resulted in improved outcomes across various tumour types. However, ICIs can cause a diverse range of immune-related adverse events (irAEs) that present a considerable challenge to the efficacy and safety of these treatments. The gut microbiota has been demonstrated to have a crucial role in modulating the tumour immune microenvironment and thus influences the effectiveness of ICIs. Accumulating evidence indicates that alterations in the composition and function of the gut microbiota are also associated with an increased risk of irAEs, particularly ICI-induced colitis. Indeed, these changes in the gut microbiota can contribute to the pathogenesis of irAEs. In this Review, we first summarize the current clinical challenges posed by irAEs. We then focus on reported correlations between alterations in the gut microbiota and irAEs, especially ICI-induced colitis, and postulate mechanisms by which these microbial changes influence the occurrence of irAEs. Finally, we highlight the potential value of gut microbial changes as biomarkers for predicting irAEs and discuss gut microbial interventions that might serve as new strategies for the management of irAEs, including faecal microbiota transplantation, probiotic, prebiotic and/or postbiotic supplements, and dietary modulations.

The Microbiome and Cancer: A Translational Science Review

Importance

Growing evidence suggests that microbes located within the gastrointestinal tract and other anatomical locations influence the development and progression of diseases such as cancer.

Observations

Clinical and preclinical evidence suggests that microbes in the gastrointestinal tract and other anatomical locations, such as the respiratory tract, may affect carcinogenesis, development of metastases, cancer treatment response, and cancer treatment-related adverse effects. Within tumors of patients with cancer, microbes may affect response to treatment, and therapies that reduce or eliminate these microbes may improve outcomes in patients with cancer. Modulating gastrointestinal tract (gut) microbes through fecal microbiota transplant and other strategies such as dietary intervention (eg, high-fiber diet intervention) has improved outcomes in small studies of patients treated with cancer immunotherapy. In contrast, disruption of the gut microbiota by receipt of broad-spectrum antibiotics prior to treatment with cancer immunotherapy has been associated with poorer overall survival and higher rates of adverse effects in patients treated with immune checkpoint blockade for solid tumors and also with chimeric antigen receptor T-cell therapy for hematologic malignancies.

Conclusions and Relevance

Microbes in the gut and other locations in the body may influence the development and progression of cancer and may affect the response to adverse effects from cancer therapy. Future therapies targeting microbes in the gut and other locations in the body could potentially improve outcomes in patients with cancer.

Deep Sequencing of Crohn's Disease Lamina Propria Phagocytes Identifies Pathobionts and Correlates With Pro-Inflammatory Gene Expression

BACKGROUND

Crohn's disease (CD) is characterized by an inflammatory response to gut microbiota. Macrophages and dendritic cells play an active role in CD inflammation. Specific microbiota have been implicated in the pathogenesis of ileal CD. We investigated the phagocyte-associated microbiome using an unbiased sequencing approach to identify potential pathobionts and elucidate the host response to these microbes.

METHODS

We collected ileal and colonic mucosal biopsies from CD patients and controls without inflammatory bowel disease (IBD), isolated lamina propria phagocytes (CD11b+ cells), and performed deep RNA sequencing (n = 37). Reads were mapped to the human genome for host gene expression analysis and a prokaryotic database for microbiome taxonomic and metatranscriptomic profiling. Results were confirmed in a second IBD cohort (n = 17). Lysed lamina propria cells were plated for bacterial culturing; isolated colonies underwent whole genome sequencing (n = 11).

RESULTS

Crohn's disease ileal phagocytes contained higher relative abundances of Escherichia coli, Ruminococcus gnavus, and Enterocloster spp. than those from controls. CD phagocyte-associated microbes had increased expression of lipopolysaccharide (LPS) biosynthesis pathways. Phagocytes with a higher pathobiont burden showed increased expression of pro-inflammatory and antimicrobial genes, including PI3 (antimicrobial peptide) and BPIFB1 (LPS-binding molecule). E. coli isolated from the CD lamina propria had more flagellar motility and antibiotic resistance genes than control-derived strains.

CONCLUSIONS

Lamina propria resident phagocytes harbor bacterial strains that may act as pathobionts in CD. Our findings shed light on the role of pathobionts and the immune response in CD pathogenesis and suggest new targets for therapies.

Bifidobacterium animalis Subsp. lactis PB200 Improves Intestinal Barrier Function and Flora Disturbance in Mice with Antibiotic-Induced Intestinal Injury

Background/Objectives: Overuse or misuse of antibiotics could cause adverse effects such as gut microbiota dysbiosis and intestinal barrier dysfunction. Probiotic intervention could effectively alleviate these symptoms. However, the precise efficacy of Bifidobacterium animalis subsp. lactis PB200 (B. lactis PB200) in mitigating antibiotic-induced intestinal injury remains unclear. Objective: The aim of this study was to systematically evaluate the effects of B. lactis PB200 on intestinal barrier injury and gut microbiota dysbiosis in a murine model of antibiotic-induced intestinal injury. Methods: BALB/c mice were administered ceftriaxone sodium via oral gavage for seven consecutive days, followed by probiotic intervention daily via gastric gavage for 4 weeks. Results: The results indicated that B. lactis PB200 played a positive role in enhancing intestinal barrier function, as evidenced by the restored intestinal morphology, and elevated the expression of tight junctions including ZO-1, Claudin-4 and Occludin (2.76-fold, 4.39-fold, and 2.61-fold, respectively) compared to that in the Model group. B. lactis PB200 normalized the levels of serum pro- and anti-inflammatory factors, including IL-1β, IL-6, TNF-α and IL-10, and elevated the diversity and richness of gut microbiota. B. lactis PB200 significantly elevated the levels of propionic acid and butyric acid, with increases of 1.67-fold and 2.82-fold, respectively, compared to the Model group. Notably, B. lactis PB200 reduced the abundance of Enterocloster and increased the abundance of Parabacteroides, promoting the rebalance of gut microbiota. Conclusions: Taken together, these findings highlighted the significant potential of B. lactis PB200 in alleviating intestinal barrier damage and restoring the balance of gut microbiota caused by an antibiotic.

New insights into gut microbiota-prostate cancer crosstalk

Recent evidence underscores a reciprocal relationship between the gut microbiota and prostate cancer (PCa). Dysbiosis, often driven by Western dietary habits and antibiotic use, can heighten systemic inflammation and hinder antitumor immunity, thereby fostering PCa onset and progression. Conversely, certain gut microbes and their metabolites may protect against tumor growth by modulating immune and hormonal pathways that impact therapeutic responses, including androgen deprivation therapy (ADT). Emerging evidence links gut microbial shifts to PCa aggressiveness, potentially sustaining local androgen production and promoting resistance. In this review, we explore current understanding of the gut-PCa interplay, highlighting key knowledge gaps and the need for further research to clarify how targeting the microbiome might influence PCa outcomes.

The gut microbiome and cancer: from tumorigenesis to therapy

The gut microbiome has a crucial role in cancer development and therapy through its interactions with the immune system and tumour microenvironment. Although evidence links gut microbiota composition to cancer progression, its precise role in modulating treatment responses remains unclear. In this Review, we summarize current knowledge on the gut microbiome's involvement in cancer, covering its role in tumour initiation and progression, interactions with chemotherapy, radiotherapy and targeted therapies, and its influence on cancer immunotherapy. We discuss the impact of microbial metabolites on immune responses, the relationship between specific bacterial species and treatment outcomes, and potential microbiota-based therapeutic strategies, including dietary interventions, probiotics and faecal microbiota transplantation. Understanding these complex microbiota-immune interactions is critical for optimizing cancer therapies. Future research should focus on defining microbial signatures associated with treatment success and developing targeted microbiome modulation strategies to enhance patient outcomes.

Cutting-Edge Advancements in the Antibiotics-Gut Microbiota-Urinary Tumour Axis

Gut microbiota regulates urological tumors. Antibiotics induce dysbiosis, altering tumor progression/therapy: reducing carcinogen metabolism but impairing immunity. Specific bacteria enhance immune responses and combat endocrine resistance. Future research should unravel microbiota-cancer links and develop microbiome-targeted therapies to optimize outcomes while preserving diversity.

Gut microbiota - bidirectional modulator: role in inflammatory bowel disease and colorectal cancer

The gut microbiota is a diverse ecosystem that significantly impacts human health and disease. This article focuses on how the gut microbiota interacts with inflammatory bowel diseases and colorectal tumors, especially through immune regulation. The gut microbiota plays a role in immune system development and regulation, while the body's immune status can also affect the composition of the microbiota. These microorganisms exert pathogenic effects or correct disease states in gastrointestinal diseases through the actions of toxins and secretions, inhibition of immune responses, DNA damage, regulation of gene expression, and protein synthesis. The microbiota and its metabolites are essential in the development and progression of inflammatory bowel diseases and colorectal tumors. The complexity and bidirectionality of this connection with tumors and inflammation might render it a new therapeutic target. Hence, we explore therapeutic strategies for the gut microbiota, highlighting the potential of probiotics and fecal microbiota transplantation to restore or adjust the microbial community. Additionally, we address the challenges and future research directions in this area concerning inflammatory bowel diseases and colorectal tumors.

Gut reactions: harnessing microbial metabolism to fuel next-generation cancer immunotherapy

Immunotherapies, including immune checkpoint inhibitors and chimeric antigen receptor-T cell therapies, depend heavily on a healthy and diverse gut microbiome for optimal efficacy. Dysbiosis, or an imbalance in gut microbial composition and function, can diminish immunotherapy responses by altering immune cell trafficking and metabolic output. Key microbial metabolites such as short-chain fatty acids and modified bile acids shape host immunity and influence T-cell function, while their disruption can foster an immunosuppressive microenvironment. Emerging strategies to restore a balanced microbiome and boost treatment outcomes include dietary interventions, supplementation with beneficial microbes, and fecal microbiota transplantation. Despite these advances, challenges remain in defining dysbiosis, identifying reliable biomarkers, and tailoring microbiota-centered interventions. Nevertheless, as our understanding evolves, the gut microbiome holds promise as an integral component of personalized cancer immunotherapy.

Coupling culturomics and metagenomics sequencing to characterize the gut microbiome of patients with cancer treated with immune checkpoint inhibitors

BACKGROUND

The gut microbiome represents a novel biomarker for melanoma and non-small cell lung cancer (NSCLC) patients treated with immune checkpoint inhibitors (ICI). Gut microbiome metagenomics profiling studies of patients treated with immunotherapy identified bacteria associated with ICI efficacy, while others have been linked to resistance. However, limitations of metagenomics sequencing, such as complex bioinformatic processing requirements, necessity of a threshold for positive detection, and the inability to detect live organisms, have hindered our ability to fully characterize the gut microbiome. Therefore, combining metagenomics with high-throughput culture-based techniques (culturomics) represents an ideal strategy to fully characterize microbiome composition to more robustly position the microbiome as a biomarker of response to ICI.

METHODS

We performed culturomics using fecal samples from 22 patients from two academic centres in Canada and the United Kingdom with NSCLC and cutaneous melanoma treated with ICI (cancer group), comparing their microbiome composition to that of 7 healthy volunteers (HV), along with matching shotgun metagenomics sequencing.

RESULTS

For culturomics results, 221 distinct species were isolated. Among these 221 distinct species, 182 were identified in the cancer group and 110 in the HV group. In the HV group, the mean species richness was higher compared to the cancer group (34 vs. 18, respectively, p = 0.002). Beta diversity revealed separate clusters between groups (p = 0.004). Bifidobacterium spp. and Bacteroides spp. were enriched in HV, while cancer patients showed an overrepresentation of Enterocloster species, as well as Veillonella parvula. Next, comparing cancer patients' clinical outcomes to ICI, we observed that among the 20 most abundant bacteria present in non-responder patients, 2 belonged to the genus Enterocloster, along with an enrichment of Hungatella hathewayi and Cutibacterium acnes. In contrast, responders to ICI exhibited a predominance of Bacteroides spp. In NSCLC patients, metagenomics analysis revealed that of the 154 bacteria species isolated through culturomics, 61/154 (39%) were also identified by metagenomics sequencing. Importantly, 94 individual species were uniquely detected by culturomics.

CONCLUSION

These findings highlight that culturomics and metagenomics can serve as complementary tools to characterize the microbiome in patients with cancer. This integrated approach uncovers specific microbiome signatures that differentiate HV from cancer patients, and identifies specific species associated with therapy response and resistance.

Understanding the microbiome as a mediator of bladder cancer progression and therapeutic response

Bladder cancer (BCa) remains a significant source of morbidity and mortality. BCa is one of the most expensive tumors to treat, in part because of a lack of nonsurgical options. The recent advent of immunotherapy, alone or in combination with other compounds, has improved therapeutic options. Resistance to immunotherapy remains common, and many patients do not have durable response. Recent advances indicate immunotherapy efficacy may be tied in part to the endogenous bacteria present in our body, more commonly referred to as the microbiome. Laboratory and clinical data now support the idea that a healthy microbiome is critical to effective response to immunotherapy. At the same time, pathogenic interactions between the microbiome and immune cells can also serve to drive formation of tumors, increasing the complexity of these interactions. Given the rising importance of immunotherapy in BCa, understanding how we might be able to alter the microbiome to improve therapeutic efficacy offers a novel route to improved patient care. The goal of this review is to examine our current understanding of microbial interactions with the immune system and cancer with an emphasis on BCa. We will further attempt to define both current gaps in knowledge and future directions that may yield beneficial results to the field.

Impact of the ONCOBIOME network in cancer microbiome research

The European Union-sponsored ONCOBIOME network has spurred an international effort to identify and validate relevant gut microbiota-related biomarkers in oncology, generating a unique and publicly available microbiome resource. ONCOBIOME explores the effects of the microbiota on gut permeability and metabolism as well as on antimicrobial and antitumor immune responses. Methods for the diagnosis of gut dysbiosis have been developed based on oncomicrobiome signatures associated with the diagnosis, prognosis and treatment responses in patients with cancer. The mechanisms explaining how dysbiosis compromises natural or therapy-induced immunosurveillance have been explored. Through its integrative approach of leveraging multiple cohorts across populations, cancer types and stages, ONCOBIOME has laid the theoretical and practical foundations for the recognition of microbiota alterations as a hallmark of cancer. ONCOBIOME has launched microbiota-centered interventions and lobbies in favor of official guidelines for avoiding diet-induced or iatrogenic (for example, antibiotic- or proton pump inhibitor-induced) dysbiosis. Here, we review the key advances of the ONCOBIOME network and discuss the progress toward translating these into oncology clinical practice.

Oncobiomics: Leveraging Microbiome Translational Research in Immuno-Oncology for Clinical-Practice Changes

Growing evidence suggests that cancer should not be viewed solely as a genetic disease but also as the result of functional defects in the metaorganism, including disturbances in the gut microbiota (i.e., gut dysbiosis). The human microbiota plays a critical role in regulating epithelial barrier function in the gut, airways, and skin, along with host metabolism and systemic immune responses against microbes and cancer. Collaborative international networks, such as ONCOBIOME, are essential in advancing research equity and building microbiome resources to identify and validate microbiota-related biomarkers and therapies. In this review, we explore the intricate relationship between the microbiome, metabolism, and cancer immunity, and we propose microbiota-based strategies to improve outcomes for individuals at risk of developing cancer or living with the disease.

Assessing the impact of probiotics on immunotherapy effectiveness and antibiotic-mediated resistance in cancer: a systematic review and meta-analysis

Background

Probiotics have been demonstrated to exert a potential clinical enhancing effect in cancer patients receiving immune checkpoint inhibitors (ICIs), while antibiotics exert a detrimental impact. Prior meta-analysis papers have substantial limitations and are devoid of recent published studies. Therefore, this study aimed to perform an updated meta-analysis and, for the first time, assess whether probiotics can restore the damage of antibiotics to immunotherapy.

Methods

A comprehensive literature search was conducted in three English databases and three Chinese databases with a cutoff date of August 11, 2024. The methodological quality of the studies was evaluated using the Newcastle-Ottawa Quality Assessment Scale (NOS) or the Revised Cochrane risk-of-bias tool (RoB 2). Engauge Digitizer v12.1 was employed to extract hazard ratios (HRs) with 95% confidence interval (CI) for survival outcomes when these data were not explicitly provided in the manuscripts. Meta-analysis was conducted using Stata 14 software.

Results

The study sample comprised eight retrospective and four prospective studies, involving a total of 3,142 participants. The findings indicate that probiotics significantly prolong the overall survival (OS) (I2 = 31.2%; HR=0.58, 95% CI: 0.46-0.73, p < 0.001) and progression-free survival (PFS) (I2 = 65.2%; HR=0.66, 95% CI: 0.54-0.81, p < 0.001) in cancer patients receiving ICIs, enhance the objective response rate (ORR) (I2 = 33.5%; OR=1.75, 95% CI: 1.27-2.40, p = 0.001) and disease control rate (DCR) (I2 = 50.0%; OR=1.93, 95% CI: 1.11-3.35, p = 0.002). For non-small cell lung cancer (NSCLC) patients exposed to antibiotics, the use of probiotics was associated with superior OS (I2 = 0.0%; HR=0.45, 95% CI: 0.34-0.59, p < 0.001) and PFS (I2 = 0.0%; HR=0.48, 95% CI: 0.38-0.62, p < 0.001) when compared to non-users. Subgroup differences were observed regarding the cancer type (P=0.006) and ethnic backgrounds (P=0.011) in OS.

Conclusions

The meta-analysis findings suggest that probiotics can effectively extend the survival of cancer treated with ICIs. In NSCLC, probiotics appear to mitigate the negative impact of antibiotics on immunotherapy effectiveness, which has profound clinical significance. Nevertheless, additional large-scale, high-quality randomized controlled trials are necessary to further validate these findings.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=579047, identifier CRD42024579047.

Gut microbiota as a new target for anticancer therapy: from mechanism to means of regulation

In order to decipher the relationship between gut microbiota imbalance and cancer, this paper reviewed the role of intestinal microbiota in anticancer therapy and related mechanisms, discussed the current research status of gut microbiota as a biomarker of cancer, and finally summarized the reasonable means of regulating gut microbiota to assist cancer therapy. Overall, our study reveals that the gut microbiota can serve as a potential target for improving cancer management.

Low-dose irradiation of the gut improves the efficacy of PD-L1 blockade in metastatic cancer patients

The mechanisms governing the abscopal effects of local radiotherapy in cancer patients remain an open conundrum. Here, we show that off-target intestinal low-dose irradiation (ILDR) increases the clinical benefits of immune checkpoint inhibitors or chemotherapy in eight retrospective cohorts of cancer patients and in tumor-bearing mice. The abscopal effects of ILDR depend on dosimetry (≥1 and ≤3 Gy) and on the metabolic and immune host-microbiota interaction at baseline allowing CD8+ T cell activation without exhaustion. Various strains of Christensenella minuta selectively boost the anti-cancer efficacy of ILDR and PD-L1 blockade, allowing emigration of intestinal PD-L1-expressing dendritic cells to tumor-draining lymph nodes. An interventional phase 2 study provides the proof-of-concept that ILDR can circumvent resistance to first- or second-line immunotherapy in cancer patients. Prospective clinical trials are warranted to define optimal dosimetry and indications for ILDR to maximize its therapeutic potential.

Emerging role of bile acids in colorectal liver metastasis: From molecular mechanism to clinical significance (Review)

Liver metastasis is the leading cause of colorectal cancer (CRC)‑related mortality. Microbiota dysbiosis serves a role in the pathogenesis of colorectal liver metastases. Bile acids (BAs), cholesterol metabolites synthesized by intestinal bacteria, contribute to the metastatic cascade of CRC, encompassing colorectal invasion, migration, angiogenesis, anoikis resistance and the establishment of a hepatic pre‑metastatic niche. BAs impact inflammation and modulate the immune landscape within the tumor microenvironment by activating signaling pathways, which are used by tumor cells to facilitate metastasis. Given the widespread distribution of BA‑activated receptors in both tumor and immune cells, strategies aimed at restoring BA homeostasis and blocking metastasis‑associated signaling are of importance in cancer therapy. The present study summarizes the specific role of BAs in each step of colorectal liver metastasis, elucidating the association between BA and CRC progression to highlight the potential of BAs as predictive biomarkers for colorectal liver metastasis and their therapeutic potential in developing novel treatment strategies.

MAIT cell homing in intestinal homeostasis and inflammation

Mucosa-associated invariant T (MAIT) cells are a large population of unconventional T cells widely distributed in the human gastrointestinal tract. Their homing to the gut is central to maintaining mucosal homeostasis and immunity. This review discusses the potential mechanisms that guide MAIT cells to the intestinal mucosa during homeostasis and inflammation, emphasizing the roles of chemokines, chemokine receptors, and tissue adhesion molecules. The potential influence of the gut microbiota on MAIT cell homing to different regions of the human gut is also discussed. Last, we introduce how organoid technology offers a potentially valuable approach to advance our understanding of MAIT cell tissue homing by providing a more physiologically relevant model that mimics the human gut tissue. These models may enable a detailed investigation of the gut-specific homing mechanisms of MAIT cells. By understanding the regulation of MAIT cell homing to the human gut, potential avenues for therapeutic interventions targeting gut inflammatory conditions such as inflammatory bowel diseases (IBD) may emerge.

IL-21 and anti-α4β7 dual therapy during ART promotes immunological and microbiome responses in SIV-infected macaques

Despite combination antiretroviral therapy (ART), HIV causes persistent gut barrier dysfunction, immune depletion, and dysbiosis. Furthermore, ART interruption results in reservoir reactivation and rebound viremia. Both IL-21 and anti-α4β7 improve gut barrier functions, and we hypothesized that combining them would synergize as a dual therapy to improve immunological outcomes in SIV-infected rhesus macaques (RMs). We found no significant differences in CD4+ T cell reservoir size by intact proviral DNA assay. SIV rebounded in both dual-treated and control RMs following analytical therapy interruption (ATI), with time to rebound and initial rebound viremia comparable between groups; however, dual-treated RMs showed slightly better control of viral replication at the latest time points after ATI. Additionally, following ATI, dual-treated RMs showed immunological benefits, including T cell preservation and lower PD-1+ central memory T cell (TCM) frequency. Notably, PD-1+ TCMs were associated with reservoir size, which predicted viral loads (VLs) after ATI. Finally, 16S rRNA-Seq revealed better recovery from dysbiosis in treated animals, and the butyrate-producing Firmicute Roseburia predicted PD-1-expressing TCMs and VLs after ATI. PD-1+ TCMs and gut dysbiosis represent mechanisms of HIV persistence and pathogenesis, respectively. Therefore, combining IL-21 and anti-α4β7 may be an effective therapeutic strategy to improve immunological outcomes for people with HIV.

The gut microbiome and cancer response to immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) are widely used for cancer immunotherapy, yet only a fraction of patients respond. Remarkably, gut bacteria impact the efficacy of ICIs in fighting tumors outside of the gut. Certain strains of commensal gut bacteria promote antitumor responses to ICIs in a variety of preclinical mouse tumor models. Patients with cancer who respond to ICIs have a different microbiome compared with that of patients who don't respond. Fecal microbiota transplants (FMTs) from patients into mice phenocopy the patient tumor responses: FMTs from responders promote response to ICIs, whereas FMTs from nonresponders do not promote a response. In patients, FMTs from patients who have had a complete response to ICIs can overcome resistance in patients who progress on treatment. However, the responses to FMTs are variable. Though emerging studies indicate that gut bacteria can promote antitumor immunity in the absence of ICIs, this Review will focus on studies that demonstrate relationships between the gut microbiome and response to ICIs. We will explore studies investigating which bacteria promote response to ICIs in preclinical models, which bacteria are associated with response in patients with cancer receiving ICIs, the mechanisms by which gut bacteria promote antitumor immunity, and how microbiome-based therapies can be translated to the clinic.

Gut Microbiota-Tumor Microenvironment Interactions: Mechanisms and Clinical Implications for Immune Checkpoint Inhibitor Efficacy in Cancer

Cancer immunotherapy has transformed cancer treatment in recent years, with immune checkpoint inhibitors (ICIs) emerging as a key therapeutic approach. ICIs work by inhibiting the mechanisms that allow tumors to evade immune detection. Although ICIs have shown promising results, especially in solid tumors, patient responses vary widely due to multiple intrinsic and extrinsic factors within the tumor microenvironment. Emerging evidence suggests that the gut microbiota plays a pivotal role in modulating immune responses at the tumor site and may even influence treatment outcomes in cancer patients receiving ICIs. This review explores the complex interactions between the gut microbiota and the tumor microenvironment, examining how these interactions could impact the effectiveness of ICI therapy. Furthermore, we discuss how dysbiosis, an imbalance in gut microbiota composition, may contribute to resistance to ICIs, and highlight microbiota-targeted strategies to potentially overcome this challenge. Additionally, we review recent studies investigating the diagnostic potential of microbiota profiles in cancer patients, considering how microbial markers might aid in early detection and stratification of patient responses to ICIs. By integrating insights from recent preclinical and clinical studies, we aim to shed light on the potential of microbiome modulation as an adjunct to cancer immunotherapy and as a diagnostic tool, paving the way for personalized therapeutic approaches that optimize patient outcomes.

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.

Convergent inducers and effectors of T cell paralysis in the tumour microenvironment

Tumorigenesis embodies the formation of a heterotypic tumour microenvironment (TME) that, among its many functions, enables the evasion of T cell-mediated immune responses. Remarkably, most TME cell types, including cancer cells, fibroblasts, myeloid cells, vascular endothelial cells and pericytes, can be stimulated to deploy immunoregulatory programmes. These programmes involve regulatory inducers (signals-in) and functional effectors (signals-out) that impair CD8+ and CD4+ T cell activity through cytokines, growth factors, immune checkpoints and metabolites. Some signals target specific cell types, whereas others, such as transforming growth factor-β (TGFβ) and prostaglandin E2 (PGE2), exert broad, pleiotropic effects; as signals-in, they trigger immunosuppressive programmes in most TME cell types, and as signals-out, they directly inhibit T cells and also modulate other cells to reinforce immunosuppression. This functional diversity and redundancy pose a challenge for therapeutic targeting of the immune-evasive TME. Fundamentally, the commonality of regulatory programmes aimed at abrogating T cell activity, along with paracrine signalling between cells of the TME, suggests that many normal cell types are hard-wired with latent functions that can be triggered to prevent inappropriate immune attack. This intrinsic capability is evidently co-opted throughout the TME, enabling tumours to evade immune destruction.

Gut Microbiota-Related Biomarkers in Immuno-Oncology

Carcinogenesis is associated with the emergence of protracted intestinal dysbiosis and metabolic changes. Increasing evidence shows that gut microbiota-related biomarkers and microbiota-centered interventions are promising strategies to overcome resistance to immunotherapy. However, current standard methods for evaluating gut microbiota composition are cost- and time-consuming. The development of routine diagnostic tools for intestinal barrier alterations and dysbiosis constitutes a critical unmet medical need that can guide routine treatment and microbiota-centered intervention decisions in patients with cancer. In this review, we explore the influence of gut microbiota on cancer immunotherapy and highlight gut-associated biomarkers that have the potential to be transformed into simple diagnostic tools, thus guiding standard treatment decisions in the field of immuno-oncology. Mechanistic insights toward leveraging the complex relationship between cancer immunosurveillance, gut microbiota, and metabolism open exciting opportunities for developing novel biomarkers in immuno-oncology.

Association Between Antibiotic and Outcomes of Chemoimmunotherapy for Extensive-Stage Small Cell Lung Cancer: A Multicenter Retrospective Study of 132 Patients

INTRODUCTION

To evaluate the impact of antibiotic (ATB) exposure on the outcome of chemoimmunotherapy in patients with extensive-stage small cell lung cancer (ES-SCLC).

METHODS

In this multicenter retrospective study, 132 patients with ES-SCLC who received chemoimmunotherapy were included from three hospitals in China. Patients receiving ATB within 30 days prior to initiating ICI therapy (p-ATB) and those receiving concurrent ICI therapy until cessation (c-ATB)were compared to those who did not (n-ATB). Progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and immune-related adverse events (irAEs) were assessed. To avoid immortal time bias, c-ATB was analyzed as a time-dependent covariate in the Cox proportional hazards model.

RESULTS

Among the 132 patients, 25 were included in the p-ATB group and 26 in the c-ATB group, while 81 patients were categorized in the n-ATB group. Multivariate analysis revealed no significant differences in PFS (aHR = 1.028, 95% CI: 0.666-1.589, p = 0.900) and OS (aHR = 0.957, 95% CI: 0.549-1.668, p = 0.877) between the p-ATB and n-ATB groups. Similarly, p-ATB had no significant impact on ORR (p = 0.510) or irAEs (p = 0.516). The use of c-ATB had no significant effect on either PFS (aHR: 1.165, 95% CI: 0.907-1.497; p = 0.232) or OS (aHR: 1.221, 95% CI: 0.918-1.624; p = 0.171) by multivariate analysis.

CONCLUSIONS

p-ATB has no significant impact on PFS, OS, ORR, or the incidence of irAEs in ES-SCLC patients receiving chemoimmunotherapy. Similarly, c-ATB does not seem to affect PFS or OS.

The Link Between the Gut Microbiome and Bone Metastasis

The gut microbiome is essential for regulating host metabolism, defending against pathogens, and shaping the host's immune system. Mounting evidence highlights that disruption in gut microbial communities significantly impacts cancer development and treatment. Moreover, tumor-associated microbiota, along with its metabolites and toxins, may contribute to cancer progression by promoting epithelial-to-mesenchymal transition, angiogenesis, and metastatic spread to distant organs. Bones, in particular, are common sites for metastasis due to a rich supply of growth and neovascularization factors and extensive blood flow, especially affecting patients with thyroid, prostate, breast, lung, and kidney cancers, where bone metastases severely reduce the quality of life. While the involvement of the gut microbiome in bone metastasis formation is still being explored, proposed mechanisms suggest that intestinal dysbiosis may alter the bone microenvironment via the gut-immune-bone axis, fostering a premetastatic niche and immunosuppressive milieu suitable for cancer cell colonization. Disruption in the delicate balance of bone modeling and remodeling may further create a favorable environment for metastatic growth. This review focuses on the link between beneficial or dysbiotic microbiome composition and bone homeostasis, as well as the role of the microbiome in bone metastasis development. It also provides an overview of clinical trials evaluating the impact of gut microbial community structure on bone parameters across various conditions or health-related issues. Dietary interventions and microbiota modulation via probiotics, prebiotics, and fecal microbiota transplantation help support bone health and might offer promising strategies for addressing bone-related complications in cancer.

Integrin α2 in the microenvironment and the tumor compartment of digestive (gastrointestinal) cancers: emerging regulators and therapeutic opportunities

Integrins are a family of cell surface membrane receptors and play a crucial role in facilitating bidirectional cell signaling. Integrin α2 (ITGA2) is expressed across a range of cell types, including epithelial cells, platelets, megakaryocytes, and fibroblasts, where it functions as a surface marker and it is implicated in the cell movements. The most recent findings have indicated that ITAG2 has the potential to function as a novel regulatory factor in cancer, responsible for driving tumorigenesis, inducing chemoresistance, regulating genomic instability and remodeling tumor microenvironment. Hence, we primarily focus on elucidating the biological function and mechanism of ITGA2 within the digestive tumor microenvironment, while highlighting its prospective utilization as a therapeutic target for cancer therapy.

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.

Oral reovirus reshapes the gut microbiome and enhances antitumor immunity in colon cancer

The route of oncolytic virotherapy is pivotal for immunotherapeutic efficacy in advanced cancers. In this preclinical study, an oncolytic reovirus (RC402) is orally administered to induce antitumor immunity. Oral reovirus treatment shows no gross toxicities and effectively suppresses multifocal tumor lesions. Orally administered reovirus interacts with the host immune system in the Peyer's patch of the terminal ileum, increases IgA+ antibody-secreting cells in the lamina propria through MAdCAM-1+ blood vessels, and reshapes the gut microbiome. Oral reovirus promotes antigen presentation, type I/II interferons, and T cell activation within distant tumors, but does not reach or directly infect tumor cells beyond the gastrointestinal tract. In contrast to intratumoral reovirus injection, the presence of the gut microbiome, Batf3+ dendritic cells, type I interferons, and CD8+ T cells are indispensable for orally administered reovirus-induced antitumor immunity. Oral reovirus treatment is most effective when combined with αPD-1(L1) and/or αCTLA-4, leading to complete colon tumor regression and protective immune memory. Collectively, oral reovirus virotherapy is a feasible and effective immunotherapeutic strategy in preclinical studies.

Oral Microbiome and CPT1A Function in Fatty Acid Metabolism in Oral Cancer

The oral microbiome is crucial for human health. Although oral dysbiosis may contribute to oral cancer (OC), the detailed relationships between the microbiome and OC remain unclear. In this case-control study, we aimed to elucidate the connection between the oral microbiome and mechanisms potentially involved in oral cancer. The study analyzed 1022 oral saliva samples, including 157 from oral cancer patients and 865 from healthy controls, using 16S ribosomal RNA (16S rRNA) sequencing and a Light Gradient Boosting Machine (LightGBM) model to identify four bacterial genera significantly associated with oral cancer. In patients with oral cancer, the relative abundance of Streptococcus and Parvimonas was higher; Corynebacterium and Prevotella showed decreased relative abundance; and levels of fatty acid oxidation enzymes, including Carnitine palmitoyltransferase 1A (CPT1A), long-chain acyl-CoA synthetase, acyl-CoA dehydrogenase, diacylglycerol choline phosphotransferase, and H+-transporting ATPase, were significantly higher compared to controls. Conversely, healthy controls exhibited increased levels of short-chain fatty acids (SCFAs) and CD4+T-helper cell counts. Survival analysis revealed that higher abundance of Streptococcus and Parvimonas, which correlated positively with interleukin-6, tumor necrosis factor-alpha, and CPT1A, were linked to poorer disease-free survival (DFS) and overall survival (OS) rates, while Prevotella and Corynebacterium were associated with better outcomes. These findings suggest that changes in these bacterial genera are associated with alterations in specific cytokines, CPT1A levels, SCFAs in oral cancer, with lower SCFA levels in patients reinforcing this link. Overall, these microbiome changes, along with cytokine and enzyme alterations, may serve as predictive markers, enhancing diagnostic accuracy for oral cancer.

Impact of gut microbiota and its metabolites on immunometabolism in colorectal cancer

Colorectal cancer (CRC) is highly prevalent, accounting for approximately one-tenth of cancer cases and deaths globally. It stands as the second most deadly and third most common cancer type. Although the gut microbiota has been implicated in CRC carcinogenesis for the last several decades, it remains one of the least understood risk factors for CRC development, as the gut microbiota is highly diverse and variable. Many studies have uncovered unique microbial signatures in CRC patients compared with healthy matched controls, with variations dependent on patient age, disease stage, and location. In addition, mechanistic studies revealed that tumor-associated bacteria produce diverse metabolites, proteins, and macromolecules during tumor development and progression in the colon, which impact both cancer cells and immune cells. Here, we summarize microbiota's role in tumor development and progression, then we discuss how the metabolic alterations in CRC tumor cells, immune cells, and the tumor microenvironment result in the reprogramming of activation, differentiation, functions, and phenotypes of immune cells within the tumor. Tumor-associated microbiota also undergoes metabolic adaptation to survive within the tumor environment, leading to immune evasion, accumulation of mutations, and impairment of immune cells. Finally, we conclude with a discussion on the interplay between gut microbiota, immunometabolism, and CRC, highlighting a complex interaction that influences cancer development, progression, and cancer therapy efficacy.

Impact of the Lung Microbiota on Development and Progression of Lung Cancer

The past several years have provided a more profound understanding of the role of microbial species in the lung. The respiratory tract is a delicate ecosystem of bacteria, fungi, parasites, and viruses. Detecting microbial DNA, pathogen-associated molecular patterns (PAMPs), and metabolites in sputum is poised to revolutionize the early diagnosis of lung cancer. The longitudinal monitoring of the lung microbiome holds the potential to predict treatment response and side effects, enabling more personalized and effective treatment options. However, most studies into the lung microbiota have been observational and have not adequately considered the impact of dietary intake and air pollutants. This gap makes it challenging to establish a direct causal relationship between environmental exposure, changes in the composition of the microbiota, lung carcinogenesis, and tumor progression. A holistic understanding of the lung microbiota that considers both diet and air pollutants may pave the way to improved prevention and management strategies for lung cancer.

The DAV132 colon-targeted adsorbent does not interfere with plasma concentrations of antibiotics but prevents antibiotic-related dysbiosis: a randomized phase I trial in healthy volunteers

The deleterious impact of antibiotics (ATB) on the microbiome negatively influences immune checkpoint inhibitors (ICI) response in patients with cancer. We conducted a randomized phase I study (EudraCT:2019-A00240-57) with 148 healthy volunteers (HV) to test two doses of DAV132, a colon-targeted adsorbent, alongside intravenous ceftazidime-avibactam (CZA), piperacillin-tazobactam (PTZ) or ceftriaxone (CRO) and a group without ATB. The primary objective of the study was to assess the effect of DAV132 on ATB plasma concentrations and both doses of DAV132 did not alter ATB levels. Secondary objectives included safety, darkening of the feces, and fecal ATB concentrations. DAV132 was well tolerated, with no severe toxicity and similar darkening at both DAV132 doses. DAV132 led to significant decrease in CZA or PTZ feces concentration. When co-administered with CZA or PTZ, DAV132 preserved microbiome diversity, accelerated recovery to baseline composition and protected key commensals. Fecal microbiota transplantation (FMT) in preclinical cancer models in female mice from HV treated with CZA or PTZ alone inhibited anti-PD-1 response, while transplanted samples from HV treated with ATB + DAV132 circumvented resistance to anti-PD-1. This effect was linked to activated CD8+ T cell populations in the tumor microenvironment. DAV132 represents a promising strategy for overcoming ATB-related dysbiosis and further studies are warranted to evaluate its efficacy in cancer patients.

Long-distance microbial mechanisms impacting cancer immunosurveillance

The intestinal microbiota determines immune responses against extraintestinal antigens, including tumor-associated antigens. Indeed, depletion or gross perturbation of the microbiota undermines the efficacy of cancer immunotherapy, thereby compromising the clinical outcome of cancer patients. In this review, we discuss the long-distance effects of the gut microbiota and the mechanisms governing antitumor immunity, such as the translocation of intestinal microbes into tumors, migration of leukocyte populations from the gut to the rest of the body, including tumors, as well as immunomodulatory microbial products and metabolites. The relationship between these pathways is incompletely understood, in particular the significance of the tumor microbiota with respect to the identification of host and/or microbial products that regulate the egress of bacteria and immunocytes toward tumor beds.

Immunotherapy efficacy and toxicity: Reviewing the evidence behind patient implementable strategies

The use of immune checkpoint inhibitors (ICI) in cancer treatment is expanding, offering promising outcomes but with an important risk of immune-related adverse events (irAEs). These events, stemming from an overstimulated immune system attacking healthy cells, can necessitate immunosuppressant treatment, disrupt treatment courses, and impact patients' quality of life. The analysis of ICI efficacy data has led to a better understanding of the characteristics of responders. Similarly, we are gaining clearer insights into the characteristics of patients who develop irAEs, prompting an increasing emphasis on modifiable factors associated with irAE risk. These factors include lifestyle choices and the composition of the gut microbiome. Despite comprehensive reviews exploring the microbiome's role in therapy efficacy, understanding its connection with immune-related toxicity remains incomplete. While endeavours to identify predictive biomarkers continue, lifestyle modifications emerge as a promising avenue for enhancing treatment outcomes. This review consolidates the current evidence regarding the impact of the gut microbiome on irAE occurrence. Furthermore, it focuses on actionable strategies for mitigating these adverse events, elucidating the evidence supporting dietary adjustments, supplementation, medication management, and physical activity. With the expanding range of indications for ICI therapy, a significant proportion of oncology patients, including those in early disease stages, are now exposed to these treatments. Acknowledging the importance of averting irAEs in this context, our review offers timely insights crucial for addressing the evolving challenges associated with immunotherapy across diverse oncological settings.

Global research trends on the associations between the microbiota and lung cancer: a visualization bibliometric analysis (2008-2023)

Numerous papers have been published on the microbiota in lung cancer in recent years. However, there is still a lack of bibliometric analysis of the microbiota in lung cancer in this field. Our paper did bibliometric analyses and elucidated the knowledge structure and study hotspots related to the microbiota in lung cancer patients. We screened publications reporting on the microbiota in lung cancer from 2008 to 2023 from the Web of Science Core Collection (WoSCC) database, and carried out bibliometric analyses by the application of the VOSviewers, CiteSpace and R package "bibliometrix." The 684 documents enrolled in the analysis were obtained from 331 institutions in 67 regions by 4,661 authors and were recorded in 340 journals. Annual papers are growing rapidly, and the countries of China, the United States and Italy are contributing the most to this area of research. Zhejiang University is the main research organization. Science and Cancer had significant impacts on this area. Zhang Yan had the most articles, and the Bertrand Routy had the most co-cited times. Exploring the mechanism of action of the lung and/or gut microbiota in lung cancer and therapeutic strategies involving immune checkpoint inhibitors in lung cancer are the main topics. Moreover, "gut microbiota," "immunotherapy," and "short-chain fatty acids" are important keywords for upcoming study hotspots. In conclusion, microbiota research offers promising opportunities in lung cancer, with pivotal studies exploring the mechanisms that link lung and gut microbiota to therapeutic strategies, particularly through immune checkpoint inhibitors. Moreover, the gut-lung axis emerges as a novel target for innovative treatments. Further research is essential to unravel the detailed mechanisms of this connection.

The gut microbiota improves the efficacy of immune-checkpoint inhibitor immunotherapy against tumors: From association to cause and effect

Immune-checkpoint inhibitors (ICIs), including anti-PD-1/PD-L1 therapeutic antibodies, have markedly enhanced survival across numerous cancer types. However, the limited number of patients with durable benefits creates an urgent need to identify response biomarkers and to develop novel strategies so as to improve response. It is widely recognized that the gut microbiome is a key mediator in shaping immunity. Additionally, the gut microbiome shows significant potential in predicting the response to and enhancing the efficacy of ICI immunotherapy against cancer. Recent studies encompassing mechanistic analyses and clinical trials of microbiome-based therapy have shown a cause-and-effect relationship between the gut microbiome and the modulation of the ICI immunotherapeutic response, greatly contributing to the establishment of novel strategies that will improve response and overcome resistance to ICI treatment. In this review, we outline the current state of research advances and discuss the future directions of utilizing the gut microbiome to enhance the efficacy of ICI immunotherapy against tumors.

Exploring the Role of the Gut Microbiota in Modulating Colorectal Cancer Immunity

The gut microbiota plays an essential role in maintaining immune homeostasis and influencing the immune landscape within the tumor microenvironment. This review aims to elucidate the interactions between gut microbiota and tumor immune dynamics, with a focus on colorectal cancer (CRC). The review spans foundational concepts of immuno-microbial interplay, factors influencing microbiome composition, and evidence linking gut microbiota to cancer immunotherapy outcomes. Gut microbiota modulates anti-cancer immunity through several mechanisms, including enhancement of immune surveillance and modulation of inflammatory responses. Specific microbial species and their metabolic byproducts can significantly influence the efficacy of cancer immunotherapies. Furthermore, microbial diversity within the gut microbiota correlates with clinical outcomes in CRC, suggesting potential as a valuable biomarker for predicting response to immunotherapy. Conclusions: Understanding the relationship between gut microbiota and tumor immune responses offers potential for novel therapeutic strategies and biomarker development. The gut microbiota not only influences the natural history and treatment response of CRC but also serves as a critical modulator of immune homeostasis and anti-cancer activity. Further exploration into the microbiome's role could enhance the effectiveness of existing treatments and guide the development of new therapeutic modalities.

Immunomodulation in Endometriosis: Investigating the interrelationship between VISTA expression and Escherichia.Shigella-Associated metabolites

AIMS

Endometriosis is characterized by an abnormal immune microenvironment. Despite the extensive use of immune therapies, the application of immune checkpoint inhibitors in endometriosis lacks confidence due to the instability of preclinical research data. This study aims to elucidate the regulation of the immune inhibitory checkpoint VISTA and its effects on T cells from the perspective of microbiota and metabolism.

MAIN METHODS

We divided endometriosis patients into high and low groups based on the expression levels of VISTA in lesion tissues. We collected peritoneal fluid samples from these two groups and performed 16 s RNA sequencing and metabolomics analysis to investigate microbial diversity and differential metabolites. Through combined analysis, we identified microbial-associated metabolites and validated their correlation with VISTA and CD8 + T cells using ELISA and immunofluorescence. In vitro experiments were conducted to confirm the regulatory relationship among these factors.

KEY FINDINGS

Our findings revealed a distinct correlation between VISTA expression and the microbial colony Escherichia.Shigella. Moreover, we identified the metabolites LTD4-d5 and 2-n-Propylthiazolidine-4-carboxylic acid as being associated with both Escherichia.Shigella and VISTA expression. In vitro experiments confirmed the inhibitory effects of these metabolites on VISTA expression, while they demonstrated a positive regulation of CD8 + T cell infiltration into endometriotic lesions.

SIGNIFICANCE

This study reveals the connection between microbial diversity, metabolites, and VISTA expression in the immune microenvironment of endometriosis, providing potential targets for therapeutic interventions.