Gut microbiome modulates response to anti-PD-1 immunotherapy in melanoma patients

From chaos to order: optimizing fecal microbiota transplantation for enhanced immune checkpoint inhibitors efficacy

The integration of fecal microbiota transplantation (FMT) with immune checkpoint inhibitors (ICIs) presents a promising approach for enhancing cancer treatment efficacy and overcoming therapeutic resistance. This review critically examines the controversial effects of FMT on ICIs outcomes and elucidates the underlying mechanisms. We investigate how FMT modulates gut microbiota composition, microbial metabolite profiles, and the tumor microenvironment, thereby influencing ICIs effectiveness. Key factors influencing FMT efficacy, including donor selection criteria, recipient characteristics, and administration protocols, are comprehensively discussed. The review delineates strategies for optimizing FMT formulations and systematically monitoring post-transplant microbiome dynamics. Through a comprehensive synthesis of evidence from clinical trials and preclinical studies, we elucidate the potential benefits and challenges of combining FMT with ICIs across diverse cancer types. While some studies report improved outcomes, others indicate no benefit or potential adverse effects, emphasizing the complexity of host-microbiome interactions in cancer immunotherapy. We outline critical research directions, encompassing the need for large-scale, multi-center randomized controlled trials, in-depth microbial ecology studies, and the integration of multi-omics approaches with artificial intelligence. Regulatory and ethical challenges are critically addressed, underscoring the imperative for standardized protocols and rigorous long-term safety assessments. This comprehensive review seeks to guide future research endeavors and clinical applications of FMT-ICIs combination therapy, with the potential to improve cancer patient outcomes while ensuring both safety and efficacy. As this rapidly evolving field advances, maintaining a judicious balance between openness to innovation and cautious scrutiny is crucial for realizing the full potential of microbiome modulation in cancer immunotherapy.

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.

Brown B, Chan TA, Chand D, Constanzo J, Demaria S, I. Gabrilovich D, Golden E, Godkin A, Guha C, P. Gupta G, Hasan A, G. Herrera F, Kaufman H, Li D, A. Melcher A, McDonald S, Merghoub T, Monjazeb AM, Paris S, Pitroda S, Sadanandam A, Schaue D, Santambrogio L, Szapary P, Sage J, W. Welsh J, Wilkins A, H. Young K, Wennerberg E, Zitvogel L, Galluzzi L, Deutsch E, C. Formenti S. Updates on radiotherapy-immunotherapy combinations: Proceedings of 8th Annual ImmunoRad Conference

The annual ImmunoRad Conference has established itself as a recurrent occasion to explore the possibility of combining radiation therapy (RT) and immunotherapy (IT) for clinical cancer management. Bringing together a number of preclinical and clinical leaders in the fields of radiation oncology, immuno-oncology and IT, this annual event fosters indeed essential conversations and fruitful exchanges on how to address existing challenges to expand the therapeutic value of RT-IT combinations. The 8th edition of the ImmunoRad Conference, which has been held in October 2024 at the Weill Cornell Medical College of New York City, highlighted exciting preclinical and clinical advances at the interface between RT and IT, setting the stage for extra progress toward extended benefits for patients with an increasing variety of tumor types. Here, we critically summarize the lines of investigation that have been discussed at the occasion of the 8th Annual ImmunoRad Conference.

The gut microbiota: an emerging modulator of drug resistance in hepatocellular carcinoma

Liver cancer is usually diagnosed at an advanced stage and is the third most common cause of cancer-related death worldwide. In addition to the lack of effective treatment options, resistance to therapeutic drugs is a major clinical challenge. The gut microbiota has recently been recognized as one of the key factors regulating host health. The microbiota and its metabolites can directly or indirectly regulate gene expression in the liver, leading to gut-liver axis dysregulation, which is closely related to liver cancer occurrence and the treatment response. Gut microbiota disturbance may participate in tumor progression and drug resistance through metabolite production, gene transfer, immune regulation, and other mechanisms. However, systematic reviews on the role of the gut microbiota in drug resistance in liver cancer are lacking. Herein, we review the relationships between the gut microbiota and the occurrence and drug resistance of hepatocellular carcinoma, summarize the emerging mechanisms underlying gut microbiota-mediated drug resistance, and propose new personalized treatment options to overcome this resistance.

Research hotspots and trends of immunotherapy and melanoma: A bibliometric analysis during 2014-2024

Over the last decade, the increasing global prevalence of melanoma has sparked growing interest in immunotherapies, which show significant potential against this form of skin cancer. This research aims to offer a framework to guide future studies and inspire new research directions. In this study, we used the Web of Science Core Collection to collect papers on immunotherapy and melanoma published between 2014 and 2024. With Excel and visualization tools like VOSviewer, COOC 13.2, Citespace, and Bibliometrix (R-Tool of R-Studio), we analyzed the data to spot trends and new focuses in the research. Our findings indicate a substantial surge in research activity concerning immunotherapy and melanoma between 2014 and 2024. The USA and China emerged as leading contributors, engaging in extensive and close collaborative efforts with European counterparts. Furthermore, seven of the top 10 research institutions are located in the USA, with the MD Anderson Cancer Center in Texas being the most productive. In addition, the Journal of Cancer Immunotherapy is the journal with the most articles published in the field. Professor Georgina V. Long from the Melanoma Institute at the University of Sydney was one of the most productive scholars. Keyword analysis shows that immune checkpoint inhibitors, tumor microenvironment and targeted therapies are key areas of interest for the research community. This paper uses bibliometric analysis to outline research trends and key points in immunotherapy and melanoma from 2014 to 2024, which helps understand the current research and guides future research directions.

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.

To explore the potential combined treatment strategy for colorectal cancer: Inhibition of cancer stem cells and enhancement of intestinal immune microenvironment

BACKGROUND

The antibiotic salinomycin, a well-known cancer stem cell inhibitor, may impact the diversity of the intestinal microbiota in colorectal cancer (CRC) mice, which plays a pivotal role in shaping the immune system. This study explores the anti-cancer effects and mechanisms of combining salinomycin and fecal microbiota transplantation (FMT) in treating CRC.

METHODS

FMT was given via enema, while salinomycin was injected intraperitoneally into the CRC mouse model induced by azoxymethane/dextran sodium sulfate.

RESULTS

In CRC mice, a large number of LGR5-labeled cancer stem cells and severe disturbances in the intestinal microbiota were observed. Interestingly, salinomycin inhibited the proliferation of cancer stem cells without exacerbating the microbial disorder as expected. In comparison to salinomycin treatment, the combination of salinomycin and FMT significantly improved pathological damage and restored intestinal microbial diversity, which is responsible for shaping the anti-cancer immune microenvironment. The supplementation of FMT significantly increased the levels of propionic acid and butyric acid while also promoting the infiltration of CD8+ T cells and Ly6G+ neutrophils, as well as reducing F4/80+ macrophage recruitment. Notably, cytokines that were not impacted by salinomycin exhibited robust reactions to alterations in the gut microbiota. These included pro-inflammatory factors (IL6, IL12b, IL17, and IL22), chemokine-like protein OPN, and immunosuppressive factor PD-L1.

CONCLUSIONS

Salinomycin plays the role of "eliminating pathogenic qi," targeting cancer stem cells; FMT plays the role of "strengthening vital qi," reversing the intestinal microbiota disorder and enhancing anti-cancer immunity. They have a synergistic effect on the development of CRC.

Gut microbiota in melanoma: Effects and pathogeneses

The gut microbiota exhibits intricate connections with the body's immune system and holds significant implications for various diseases and cancers. Currently, accumulating evidence suggests a correlation between the composition of the gut microbiota and the development, treatment, and prognosis of melanoma. However, the underlying pathogenesis remains incompletely elucidated. In this comprehensive review, we present an in-depth review of the role played by gut microbiota in melanoma tumorigenesis, growth, metastasis, treatment response, and prognosis. Furthermore, we discuss the potential utility of gut microbiota as a promising prognostic marker. Lastly, we summarize three routes through which gut microbiota influences melanoma: immunity, aging, and the endocrine system. By modulating innate and adaptive immunity in patients with melanoma across different age groups and genders, the gut microbiota plays a crucial role in anti-tumor immune regulation from tumorigenesis to prognosis management, thereby impacting tumor growth and metastasis. This review also addresses current study limitations while highlighting future research prospects.

Unraveling the potential of bioengineered microbiome-based strategies to enhance cancer immunotherapy

The human microbiome plays a pivotal role in the field of cancer immunotherapy. The microbial communities that inhabit the gastrointestinal tract, as well as the bacterial populations within tumors, have been identified as key modulators of therapeutic outcomes, affecting immune responses and reprogramming the tumor microenvironment. Advances in synthetic biology have made it possible to reprogram and engineer these microorganisms to improve antitumor activity, enhance T-cell function, and enable targeted delivery of therapies to neoplasms. This review discusses the role of the microbiome in modulating both innate and adaptive immune mechanisms-ranging from the initiation of cytokine production and antigen presentation to the regulation of immune checkpoints-and discusses how these mechanisms improve the efficacy of immune checkpoint inhibitors. We highlight significant advances with bioengineered strains like Escherichia coli Nissle 1917, Lactococcus lactis, Bifidobacterium, and Bacteroides, which have shown promising antitumor efficacy in preclinical models. These engineered microorganisms not only efficiently colonize tumor tissues but also help overcome resistance to standard therapies by reprogramming the local immune environment. Nevertheless, several challenges remain, such as the requirement for genetic stability, effective tumor colonization, and the control of potential safety issues. In the future, the ongoing development of genetic engineering tools and the optimization of bacterial delivery systems are crucial for the translation of microbiome-based therapies into the clinic. This review highlights the potential of bioengineered microbiota as an innovative, personalized approach in cancer immunotherapy, bringing hope for more effective and personalized treatment options for patients with advanced malignancies.

Exceptional responders to immunotherapy in pancreatic cancer: A multi-institutional case series of a rare occurrence

INTRODUCTION

Immunotherapy has emerged as a standard treatment option for multiple solid tumors. However, most patients with pancreatic cancer (PC) do not derive a significant benefit. Identification and analyses of exceptional responders could eventually offer hints as to why PC is resistant to immunotherapy.

METHODS

Oncologists from cancer centers in the United States were contacted to identify patients with PC who responded to immunotherapy. Exceptional responders were defined as those having either partial (PR) or complete response (CR) based on Response Evaluation Criteria in Solid Tumors, or biochemical response (CA 19-9 levels) after starting immunotherapy. Patients receiving concurrent chemotherapy were excluded.

RESULTS

14 patients met inclusion criteria. Immunotherapy drugs included checkpoint inhibitors and macrophage inhibitors. Eight patients (42%) were MSI (microsatellite instability)-high. Radiologically, 82% had PR. Four patients (28%) had marked reduction in CA 19-9. The median progression-free survival was 12 months from the start of immunotherapy. Median survival was not reached. The 1- and 2-year survival probabilities were 80%, 70% respectively.

CONCLUSION

Majority of clinical trials evaluating immunotherapy in PC have yielded disappointing response rates compared to other solid tumors. Our case series adds to published data from early-phase trials supporting the promise of immunotherapy in some patients with PC.

Harnessing the human microbiome and its impact on immuno-oncology and nanotechnology for next-generation cancer therapies

The integration of microbiome research and nanotechnology represents a significant advancement in immuno-oncology, potentially improving the effectiveness of cancer immunotherapies. Recent studies highlight the influential role of the human microbiome in modulating immune responses, presenting new opportunities to enhance immune checkpoint inhibitors (ICIs) and other cancer therapies. Nanotechnology offers precise drug delivery and immune modulation capabilities, minimizing off-target effects while maximizing therapeutic outcomes. This review consolidates current knowledge on the interactions between the microbiome and the immune system, emphasizing the microbiome's impact on ICIs, and explores the incorporation of nanotechnology in cancer treatment strategies. Additionally, it provides a forward-looking perspective on the synergistic potential of microbiome modulation and nanotechnology to overcome existing challenges in immuno-oncology. This integrated approach may enhance the personalization and effectiveness of next-generation cancer treatments, paving the way for transformative patient care.

Comparative Colonisation Ability of Human Faecal Microbiome Transplantation Strategies in Murine Models

The gut microbiome plays a crucial role in maintaining intestinal homeostasis and influencing immune-mediated diseases. Human faecal microbiota transplantation (FMT) is often employed in murine models to investigate the role of human microbes in disease regulation, but methods for effective colonisation require refinement. This study aimed to assess the colonisation efficiency of human microbiota in a murine model using FMT with human faeces, focusing particularly on the impact of gut microbiota depletion via polyethylene glycol (PEG) and comparing oral-gastric gavage with enema administration routes. Our findings revealed that PEG-induced depletion enhanced human microbiome colonisation in mice. Oral-gastric gavage prolonged colonisation, while enema administration facilitated quicker resolution of dysbiosis, both inducing selective human microbial colonisation in a time-dependent manner. Notably, genera such as Bacteroides, Blautia, Medicaternibacter and Bifidobacteria were successfully colonised, whereas Roseburia, Anaerostipes, Anaerobutyricum and Faecalibacterium failed to establish in the murine gut post-FMT. These findings highlight the challenges of replicating human gut microbiota in murine models and underscore the importance of selecting appropriate FMT methods based on desired outcomes. This study provides valuable insights into the colonisation dynamics of human microbiota in mice, contributing to the development of more effective FMT strategies for disease treatment.

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.

Microbiome in prostate cancer: pathogenic mechanisms, multi-omics diagnostics, and synergistic therapies

BACKGROUND

Prostate cancer (PCa) is a leading cause of cancer-related deaths in men, with the microbiome emerging as a significant factor in its development and progression. Understanding the microbiome's role could provide new insights into PCa pathogenesis and treatment.

OBJECTIVE

This review aims to explore the interactions between the microbiome and PCa, focusing on microbial imbalances and their effects on immune responses, inflammation, and hormone levels. It also discusses advanced research techniques and the potential for microbiome modulation in PCa management.

METHODS

The review synthesizes current literature on the microbiome's role in PCa, highlighting differences in microbial composition between cancerous and healthy prostate tissues. It examines techniques such as high-throughput sequencing and metagenomics and explores the mechanisms through which the microbiome influences PCa.

CONCLUSIONS

The review reveals substantial microbial differences in prostate tissues of PCa patients compared to healthy individuals, indicating a potential link between microbiome alterations and disease progression. It highlights the promise of microbiome-based strategies for diagnosis and treatment and underscores the need for further research into personalized, microbiome-centric approaches for PCa management.

Evaluation of skin cancer prevention properties of probiotics

Bacteria play a crucial role in human health and disease pathogenesis. In recent years, the therapeutic potential of probiotics has gained increasing attention, with studies suggesting their application in treating various diseases, including cancer. We evaluated clinical data supporting the use of oral and topical probiotics for skin malignancies by conducting a literature search in PubMed and Google Scholar. Although limited, clinical trials investigating probiotics in cancer prevention and treatment have shown promising results, particularly in controlling tumor progression and enhancing therapeutic outcomes. Emerging research suggests that probiotics may contribute to skin cancer prevention by modulating the gut and skin microbiomes, enhancing immune responses, exerting antioxidant and anti-inflammatory effects, and inducing apoptosis. Given their antiproliferative and pro-apoptotic effects on carcinoma cells, probiotic-based therapies may serve as potential cancer-preventive agents and adjunctive treatments during conventional therapies. Key findings from our review highlight the ability of probiotics to influence cancer progression through immune regulation, apoptosis induction, and modulation of inflammatory pathways. However, further well-designed clinical trials are needed to validate these findings and establish probiotics as a viable therapeutic approach in oncology.

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.

Molecular subtype characteristics and development of prognostic model based on inflammation-related gene in lung adenocarcinoma

As one of the leading causes of death worldwide, lung adenocarcinoma (LUAD) currently lacks satisfactory treatment outcomes. The inflammatory process, closely associated with the formation of the tumor microenvironment and immune evasion, plays a crucial role in LUAD development. This study utilized data from public databases to analyze inflammation-related genes (INF) associated with prognosis in LUAD. Based on differentially expressed INF, molecular subtypes of LUAD were identified. Subsequently, a novel INF scoring system was developed to establish a prognostic model for LUAD patients, assessing its independence and reliability. Comprehensive evaluations, including immune microenvironment infiltration features, somatic mutation characteristics, and differences in immune therapy responsiveness, were conducted to characterize the prognostic model associated with INF. We further selected MMP14 from the screened INF targets for further in vitro experiments. Experiments such as western blot, qRT-PCR, colony-forming assay and Transwell assay confirmed that downregulation of MMP14 could inhibit the cloning, proliferation and invasion of lung cancer cells, thus confirming the results of bioinformatics. Our findings provide evidence from a new perspective on the role of inflammation in LUAD and offer new insights for clinical precision and personalized therapy.

Metaproteomics in the One Health framework for unraveling microbial effectors in microbiomes

One Health seeks to integrate and balance the health of humans, animals, and environmental systems, which are intricately linked through microbiomes. These microbial communities exchange microbes and genes, influencing not only human and animal health but also key environmental, agricultural, and biotechnological processes. Preventing the emergence of pathogens as well as monitoring and controlling the composition of microbiomes through microbial effectors including virulence factors, toxins, antibiotics, non-ribosomal peptides, and viruses holds transformative potential. However, the mechanisms by which these microbial effectors shape microbiomes and their broader functional consequences for host and ecosystem health remain poorly understood. Metaproteomics offers a novel methodological framework as it provides insights into microbial dynamics by quantifying microbial biomass composition, metabolic functions, and detecting effectors like viruses, antimicrobial resistance proteins, and non-ribosomal peptides. Here, we highlight the potential of metaproteomics in elucidating microbial effectors and their impact on microbiomes and discuss their potential for modulating microbiomes to foster desired functions.

Biofilm formation by the host microbiota: a protective shield against immunity and its implication in cancer

Human-resident microbes typically cluster into biofilms - structurally organized communities embedded within a matrix of self-produced extracellular polymeric substance (EPS) that serves as a protective shield. These biofilms enhance microbial survival and functional adaptability, favoring a symbiotic relationship with the host under physiological conditions. However, biofilms exhibit a dual role in modulating the immune response. If their ability to promote tolerance is key to safeguarding homeostasis, by contrast, their persistence can overcome the cutting-edge balance resulting in immune evasion, chronic inflammation and development of numerous diseases such as cancer. Recent evidence highlights the significance of cancer-associated microbiota in shaping the tumor microenvironment (TME). These microbial inhabitants often exhibit biofilm-like structures, which may protect them from host immune responses and therapeutic interventions. The presence of biofilm-forming microbiota within the TME may promote chronic inflammation, and release of bioactive molecules that interfere with immune surveillance mechanisms, thereby enabling cancer cells to evade immune destruction. This review delves into the complex interplay between biofilms and cancer, with particular focus on the tumor-associated microbiota and the implications of biofilm involvement in modulating the immune landscape of the TME. Addressing this intricate relationship holds promises for innovative therapeutic approaches aimed at reprogramming the microbiota-cancer axis for better clinical outcomes.

Immune checkpoint inhibitor (ICI) therapy in central nervous system cancers: State-of-the-art and future outlook

Invasive central nervous system (CNS) cancers are an area where the development of breakthrough therapies is urgently needed. For instance, conditions such as glioblastoma multiforme (GBM) are associated with poor clinical prognosis, with the majority of trials offering no improvement to marginally enhanced survival. Unleashing the potential of targeting the immune system in CNS cancers has gained attention in recent years. Inhibition of immune checkpoints such as CTLA-4, PD-1/PD-L1, TIM-3, and LAG-3 has been attempted in recent trials. While potentially offering a notable edge over other immunotherapies, multi-organ adverse events have been found with the administration of immune checkpoint inhibitors (ICIs). The present review captures the state-of-the-art evidence on ICI treatments in different CNS cancers. Also, we discuss the value of combinational therapies involving ICIs as well as next-generation therapeutics such as bispecific antibodies targeting PD-1/LAG-3/TIM-3 and CRISPR-Cas9-edited PD-1-knock-out checkpoint-resistant CAR T-cells.

Associations of Atopobium, Garderella, Megasphaera, Prevotella, Sneathia, and Streptococcus with human papillomavirus infection, cervical intraepithelial neoplasia, and cancer: a systematic review and meta-analysis

BACKGROUND

Lactobacillus spp. depleted and high diversity of vaginal microbiota is closely related to human papillomavirus infection and cervical cancer. However, the role of other microbial communities in human papillomavirus infection and cervical cancer is still unclear.

OBJECTIVE

This study aims to systematically review the existing literature and perform a meta-analysis to statistically evaluate the relationship between vaginal microbiota, human papillomavirus infection, cervical intraepithelial neoplasia, and cervical cancer at the genus level.

METHODS

A comprehensive search of PubMed, Web of Science, and Embase databases was conducted to identify relevant studies. We synthesized data on the relative abundance of specific bacterial species associated with human papillomavirus status and cervical lesions. SPSS 25.0 was used to compare relative abundance among multiple groups.

RESULTS

The meta-analysis included 17 observational studies published between 2019 and 2023, involving 2014 participants from Asia, North America, and Africa. We found that specific vaginal microorganisms, such as Gardnerella, Prevotella, Sneathia, and Streptococcus, showed increased relative abundance with the severity of cervical lesions in human papillomavirus-negative, human papillomavirus-positive, cervical intraepithelial neoplasia, and cervical cancer patients. However, no statistically significant differences were found in that regard. Notably, Prevotella was significantly more abundant in cervical cancer patients compared to human papillomavirus-negative individuals. Sneathia was also found to be more abundant in cervical intraepithelial neoplasia and cervical cancer patients.

CONCLUSIONS

The specific vaginal microbial species are associated with human papillomavirus infection status and the severity of cervical lesions that may have significant implications for the prevention and treatment strategies of cervical cancer.

Microbiota as a state-of-the-art approach in precision medicine for pancreatic cancer management: A comprehensive systematic review

Emerging evidence suggests that harnessing the microbiome holds promise for innovative diagnostic and therapeutic strategies in the management of pancreatic cancer (PC). This study aims to systematically summarize the microbial markers associated with PC and assess their potential application in clinical outcome. Forty-one studies were included to assess the associations between microbial markers and PC. Among these, 13 were developed prediction models related to the microbiome in which the highest diagnostic and prognostic model belong to blood and intratumor markers, respectively. Notably, findings that utilize microbiotas from various body sites were elucidated, demonstrating their importance as unique signatures in biomarker discovery for diverse clinical applications. This review provides unique perspectives on overcoming challenges in PC by highlighting potential microbial-related markers as non-invasive approaches. Further clinical studies should evaluate the utility and accuracy of key indicators in the microbiome as a personalized tool for managing PC.

Harnessing the Microbiome: CRISPR-Based Gene Editing and Antimicrobial Peptides in Combating Antibiotic Resistance and Cancer

The growing crisis of antibiotic resistance and the increasing incidence of cancer have prompted the exploration of innovative approaches, such as gene editing and antimicrobial peptides (AMPs). The human microbiome is integral to various aspects of health, disease, and therapeutic development, influencing metabolic pathways, immune function, and pathogen resistance. Recent advances in gene editing technologies, particularly CRISPR (clustered regularly interspaced short palindromic repeats), have opened new avenues for leveraging the microbiome to address complex medical challenges, including combating multidrug-resistant pathogens and cancer. The microbiome plays a crucial role in combating antibiotic resistance by modulating microbial communities, influencing pathogen survival and susceptibility to treatments. This review explores the microbiome's dynamic role in metabolic regulation, its contribution to cancer management, and how AMPs help maintain homeostasis and exhibit emerging anticancer properties, supported by both preclinical findings and clinical evidence. Additionally, CRISPR-based microbiome engineering offers potential to enhance host-microbiome interactions, optimizing therapeutic outcomes. The integration of microbiome metagenomics and proteomics has led to the discovery of novel AMPs with targeted anticancer effects. Innovative strategies, such as engineered probiotics and CRISPR-based microbiome engineering, present exciting prospects for next-generation therapies. Despite these advances, the translation of microbiome-based therapies into clinical settings remains challenging due to ethical, regulatory, and ecological hurdles. This review underscores the transformative potential of microbiome-based interventions, emphasizing the role of personalized medicine in maximizing therapeutic efficacy. Furthermore, we also address critical research gaps, limitations, and future directions, including optimizing AMP stability, delivery, and bioavailability, as well as overcoming the regulatory and ethical challenges in clinical translation.

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.

Tumor-colonizing Pseudoalteromonas elyakovii metabolically reprograms the tumor microenvironment and promotes breast ductal carcinoma

The correlation between the microbiota found in tumors and tumor development is being progressively understood, specifically regarding its involvement in the initiation and advancement of tumors. We examined a total of 102 samples, examining the microbial composition at the species level in each person unveiled significant variations in both the microbial makeup and tumor proportions among individuals, examining the fluctuating alterations in the microbial profile during breast cancer advancement and progression. The levels of expression for Pseudoalteromonas elyakovii were notably elevated in the tumor groups when compared to the para-cancer normal group, aligning with the results obtained from qRT-PCR analysis. The relationship between tumor immunity and microorganisms within the tumor was investigated using double immunofluorescence staining combined with SweAMI probe in situ hybridization and scRNA-seq, allowing for an in-depth analysis of intratumoral microorganisms. Experiments have demonstrated that the supernatant derived from P. elyakovii displayed a significant ability to promote tumor growth and stimulation. In summary, we describe the characteristics of the intratumoral microbiota and the tumor-promoting effects of P. elyakovii supernatant within a small dose range in ductal carcinoma of the breast and characterize the potential clinical application value of intratumoural microorganisms in the progression of cancer and immunotherapy.

IMPORTANCE

Despite the existing studies, the specific microbial factors that influence the occurrence and progression of breast cancer still remain unclear. Researchers have clarified the distinctive microbial profile related to ductal carcinoma, a common histological type of breast cancer, in order to identify tumor-specific microbes and their roles in tumorigenesis. With the tumor microbiome as the focus, the enrichment of Pseudoalteromonas elyakovii features accelerates the disease progression in patients with ductal carcinoma of the breast. This study reveals the initial role relationship and innovative findings between Pseudoalteromonas elyakovii and ductal carcinoma in the breast.

Nivolumab plus low-dose ipilimumab in hypermutated HER2-negative metastatic breast cancer: a phase II trial (NIMBUS)

In the phase II NIMBUS trial, patients with human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC) and high tumor mutational burden (TMB ≥ 9 mut/Mb) received nivolumab (3 mg/kg biweekly) and low-dose ipilimumab (1 mg/kg every 6 weeks) for 2 years or until progression. The primary endpoint was objective response rate (ORR) per RECIST 1.1 criteria. Among 30 patients enrolled, the median TMB was 10.9 mut/Mb (range: 9-110) and the confirmed objective response rate was 20%. Secondary endpoints included progression-free survival, overall survival, clinical benefit rate, and safety and tolerability, including immune-related adverse events (irAEs). A prespecified correlative outcome was to evaluate the ORR in patients with a TMB ≥ 14 mut/Mb. Patients with TMB ≥ 14 mut/Mb (n = 6) experienced higher response rates (60% vs 12%; p = 0.041) and showed a trend towards improved progression-free survival and overall survival compared to patients with TMB < 14 mut/Mb. Exploratory genomic analyses suggested that ESR1 and PTEN mutations may be associated with poor response, while clinical benefit was associated with a decrease or no change in tumor fraction by serial circulating tumor DNA during treatment. Stool microbiome analysis revealed that baseline blood TMB, PD-L1 positivity, and immune-related diarrhea are associated with distinct taxonomic profiles. In summary, some patients with hypermutated HER2-negative MBC experience extended clinical benefit with a dual immunotherapy regimen; a higher TMB, and additional genomic and microbiome biomarkers may optimize patient selection for therapy with nivolumab plus low-dose ipilimumab. (Funded by Bristol Myers Squibb; ClinicalTrials.gov identifier, NCT03789110).

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.

Huaier enhances the antitumor effects of CDK 4/6 inhibitor by remodeling the immune microenvironment and gut microbiota in breast cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Trametes robiniophila Murr (Huaier), a traditional Chinese medicine (TCM), has shown promising effects as a complementary therapy in the treatment of multiple kinds of cancers.

AIM OF THE STUDY

This study aimed to systematically evaluate whether Huaier could enhance the antitumor effects of palbociclib, a highly selective CDK4/6 inhibitor.

MATERIALS AND METHODS

A breast cancer xenograft mouse model was constructed to assess the anticancer effects of Huaier and palbociclib. Transcriptomic analysis was performed to identify the differentially expressed genes and associated pathways. Flow cytometry, immunofluorescence and immunohistochemical staining were then conducted to observe the infiltration of immune cells in the tumor microenvironment (TME). The composition of the gut microbiota was explored through 16S rDNA sequencing, and a pseudosterile mouse model was established to verify the contribution of the gut microbiota to the antitumor effects of Huaier and palbociclib.

RESULTS

Oral administration of Huaier enhanced the antitumor effects of palbociclib in breast cancer. Transcriptomic analysis of tumor tissues revealed that the differentially expressed genes were related to immune functions. Indeed, the addition of Huaier to palbociclib therapy further increased the ratio of CD8+/CD3+ T cells and the abundance of GzmB+CD8+ T cells in the TME. Mechanistically, sequencing of 16S rDNA revealed that Huaier reshaped the gut microbiota composition in favor of Akkermansia, which positively modulated antitumor immune responses. The pseudosterile mouse model verified the necessity of the gut microbiota for the synergistic effect of Huaier on palbociclib. Furthermore, butyrate, a metabolite of Akkermansia, synergized with palbociclib to suppress tumor progression and promote the infiltration of CD8+ T cells in the TME.

CONCLUSIONS

Our data suggested that Huaier augmented the antitumor effects of palbociclib by increasing the abundance of Akkermansia in gut microbiota, which contributed to the enhancement of anti-tumor immunity. Consequently, combining palbociclib with Huaier may serve as a promising strategy for the treatment of breast cancer.

Gut microbes and immunotherapy for non-small cell lung cancer: a systematic review

Emerging evidence underscores gut microbiota's role in modulating lung cancer immunotherapy outcomes, though specific impacts on immune checkpoint inhibitors (ICIs) and associated adverse events (AEs) require further clarity. This review synthesizes findings from 15 studies examining gut microbiota-ICI interactions in non-small cell lung cancer (NSCLC), alongside studies investigating antibiotics, proton pump inhibitors (PPIs), probiotics, and diet as modulating factors. Results indicate that Actinobacteria, Bacteroides, and Verrucomicrobiota correlate with positive ICI responses, while Bacillota shows variable associations; notably, Bacillota-enriched patients had fewer immunotherapy-related AEs. The administration of antibiotics and PPIs within a month before ICIs was linked to diminished efficacy, whereas probiotics correlated with enhanced outcomes. Plant-based diets are also aligned with dietary patterns supportive of ICIs. These findings suggest that analyzing gut microbiota composition could improve the ability to predict NSCLC patient responses to ICIs. Additionally, judicious use of antibiotics, PPIs, probiotics, and dietary adjustments may optimize immunotherapy outcomes and mitigate adverse effects.

The Role of the Tumor Microenvironment in Pancreatic Ductal Adenocarcinoma: Recent Advancements and Emerging Therapeutic Strategies

Pancreatic cancer (PC), with pancreatic ductal adenocarcinoma (PDAC) comprising about 90% of all cases, is one of the most aggressive and lethal solid tumors. PDAC remains one of the most significant challenges of oncology to this day due to its inadequate response to conventional treatment, gradual rise in incidence since 2004, and poor five-year survival rates. As cancer cells are the primary adversary in this uneven fight, they remain the primary research target. Nevertheless, increasing attention is being paid to the tumor microenvironment (TME). The most crucial TME constellation components are immune cells, especially macrophages, stellate cells and lymphocytes, fibroblasts, bacterial and fungal microflora, and neuronal cells. Depending on the particular phenotype of these cells, the composition of the microenvironment, and the cell ratio, patients can experience different disease outcomes and varying vulnerability to treatment approaches. This study aims to present the current knowledge and review the most up-to-date scientific findings regarding the microenvironment of PC. It contains detailed information on the structure and cellular composition of the stroma, including its impact on disease development, metastasis, and response to treatment, as well as the therapeutic opportunities that arise from targeting this tissue.

Prognostic and predictive value of IDO expression in metastatic melanoma treated with Ipilimumab

BACKGROUND

The tumor microenvironment is crucial for prognosis and response to immunotherapy in several tumor entities.

METHODS

In a multicenter retrospective study, a total of 86 tumor samples from patients with metastatic melanoma were evaluated for baseline expression of indoleamine 2,3-dioxygenase (IDO) and programmed death ligand 1 (PD-L1). Expression patterns of IDO and PD-L1 on tumor cells and antigen-presenting cells (APCs) as determined by immunohistochemical (IHC) staining of paraffin-embedded tissue sections were correlated with response to ipilimumab and overall survival (OS). Statistical analysis was performed using the Spearman correlation, the Mann-Whitney test and Kaplan-Meier estimator.

RESULTS

IDO expression in tumor cells or APCs was not predictive for treatment response. The median OS was 26 months in IDO-positive and IDO-negative patients, regardless of IDO expression in tumor cells or APCs. A correlation of IHC expression scores of IDO and PD-L1 could not be documented.

CONCLUSION

The exact role of IDO in creating an immunosuppressive tumor environment and its reversal needs to be further elucidated.

Vitamins and dietary supplements in cancer treatment: is there a need for increased usage?

INTRODUCTION

Vitamins are essential for homeostasis and proper functioning of organisms. These micronutrients prevent tumor onset by functioning as antioxidants and enzymatic cofactors involved in anti-stress and immune responses, modulating epigenetic regulators, and shaping the microbiota composition. Unbalanced diets and sedentary lifestyles contribute to obesity, associated with increasing cancer risk. Cancer patients often exhibit vitamin deficiencies due to chronic inflammation, anticancer therapies, and tumor-induced metabolic changes, leading to malnutrition and cachexia.

AREAS COVERED

This review critically analyzes preclinical and clinical studies, sourced from PubMed and ClinicalTrials.gov databases, that investigate the potential benefits of vitamin supplementation and dietary interventions, such as intermittent fasting and ketogenic diets, in mouse tumor models and cancer patients. This analysis elucidates the limitations of such interventions and suggests optimal dietary strategies to prevent cancer and enhance patients' quality of life and prognosis.

EXPERT OPINION

To date, clinical studies have found no substantial benefit of over-the-counter vitamin supplements and dietary interventions on cancer patients' health and prognosis. To prevent the spread of useless and potentially harmful products by the nutraceutical industry, establishing a regulatory authority is necessary to monitor and ensure product quality and validity before commercialization.

Mapping the genetic landscape establishing a tumor immune microenvironment favorable for anti-PD-1 response

Identifying host genetic factors modulating immune checkpoint inhibitor (ICI) efficacy is experimentally challenging. Our approach, utilizing the Collaborative Cross mouse genetic resource, fixes the tumor genomic configuration while varying host genetics. We find that response to anti-PD-1 (aPD1) immunotherapy is significantly heritable in four distinct murine tumor models (H2: 0.18-0.40). For the MC38 colorectal carcinoma system, we map four significant ICI response quantitative trait loci (QTLs) with significant epistatic interactions. The differentially expressed genes within these QTLs that define responder genetics are highly enriched for processes involving antigen processing and presentation, allograft rejection, and graft vs. host disease (all p < 1 × 10-10). Functional blockade of two top candidate immune targets, GM-CSF and IL-2RB, completely abrogates the MC38 transcriptional response to aPD1 therapy. Thus, our in vivo experimental platform is a powerful approach for discovery of host genetic factors that establish the tumor immune microenvironment propitious for ICI response.

Gut Microbiota in Patients with Tuberculosis Associated with Different Drug Exposures of Antituberculosis Drugs

Interindividual variability in drug exposure can significantly influence treatment outcomes and may lead to drug concentration-related side effects during tuberculosis (TB) treatment. Although the gut microbiota is known to affect drug metabolism, its impact on anti-TB drugs has not been thoroughly explored. This study sought to elucidate the relationship between pre-treatment gut microbiota and drug exposure levels among patients with pulmonary TB. Two cohorts were analyzed: a discovery cohort (N = 99) and a validation cohort (N = 32), both comprising patients undergoing anti-TB therapy with rifampicin, isoniazid, pyrazinamide, and ethambutol. The gut microbiota patterns of participants from the discovery cohort and the validation cohort were profiled by 16S rRNA gene sequencing and metagenomics, respectively. Analyses of both cohorts robustly established a positive association between pre-treatment microbial diversity and drug exposure, as well as significant differences in gut microbiota composition across various drug exposure groups. At the species level, Faecalibacterium prausnitzii was positively associated with drug exposure to rifampicin. Moreover, functional analysis revealed that starch and sucrose metabolism and secondary bile acid biosynthesis were more abundant in the high drug exposure group. To identify biomarkers capable of stratifying patients based on their drug exposure levels, 11 taxa, represented by Faecalibacterium, were selected in the discovery cohort (AUC = 0.992) and were confirmed in the validation cohort with high predictive accuracy (AUC = 0.894). This study demonstrated a correlation between microbial dysbiosis and reduced exposure to anti-TB medications. Optimizing treatment by regulating gut microbiota to improve drug exposure levels requires further validation through larger scale multicenter clinical trials.

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.

Single-cell transcriptomic analysis reveals gut microbiota-immunotherapy synergy through modulating tumor microenvironment

The gut microbiota crucially regulates the efficacy of immune checkpoint inhibitor (ICI) based immunotherapy, but the underlying mechanisms remain unclear at the single-cell resolution. Using single-cell RNA sequencing and subsequent validations, we investigate gut microbiota-ICI synergy by profiling the tumor microenvironment (TME) and elucidating critical cellular interactions in mouse models. Our findings reveal that intact gut microbiota combined with ICIs may synergistically increase the proportions of CD8+, CD4+, and γδ T cells, reduce glycolysis metabolism, and reverse exhausted CD8+ T cells into memory/effector CD8+ T cells, enhancing antitumor response. This synergistic effect also induces macrophage reprogramming from M2 protumor Spp1+ tumor-associated macrophages (TAMs) to Cd74+ TAMs, which act as antigen-presenting cells (APCs). These macrophage subtypes show a negative correlation within tumors, particularly during fecal microbiota transplantation. Depleting Spp1+ TAMs in Spp1 conditional knockout mice boosts ICI efficacy and T cell infiltration, regardless of gut microbiota status, suggesting a potential upstream role of the gut microbiota and highlighting the crucial negative impact of Spp1+ TAMs during macrophage reprogramming on immunotherapy outcomes. Mechanistically, we propose a γδ T cell-APC-CD8+ T cell axis, where gut microbiota and ICIs enhance Cd40lg expression on γδ T cells, activating Cd40 overexpressing APCs (e.g., Cd74+ TAMs) through CD40-CD40L-related NF-κB signaling and boosting CD8+ T cell responses via CD86-CD28 interactions. These findings highlight the potential importance of γδ T cells and SPP1-related macrophage reprogramming in activating CD8+ T cells, as well as the synergistic effect of gut microbiota and ICIs in immunotherapy through modulating the TME.

Nervous system-gut microbiota-immune system axis: future directions for preventing tumor

Tumor is one of the leading causes of death worldwide. The occurrence and development of tumors are related to multiple systems and factors such as the immune system, gut microbiota, and nervous system. The immune system plays a critical role in tumor development. Studies have also found that the gut microbiota can directly or indirectly affect tumorigenesis and tumor development. With increasing attention on the tumor microenvironment in recent years, the nervous system has emerged as a novel regulator of tumor development. Some tumor therapies based on the nervous system have also been tested in clinical trials. However, the nervous system can not only directly interact with tumor cells but also indirectly affect tumor development through the gut microbiota. The nervous system-mediated gut microbiota can regulate tumorigenesis, growth, invasion, and metastasis through the immune system. Here, we mainly explore the potential effects of the nervous system-gut microbiota-immune system axis on tumorigenesis and tumor development. The effects of the nervous system-gut microbiota-immune system axis on tumors involve the nervous system regulating immune cells through the gut microbiota, which can prevent tumor development. Meanwhile, the direct effects of the gut microbiota on tumors and the regulation of the immune system by the nervous system, which can affect tumor development, are also reviewed.

Respiratory microbiota diversity as a predictive biomarker for the efficacy of PD‑1 blockades in patients with advanced non‑small cell lung cancer: A retrospective exploratory study

Despite advancements in immunotherapy, particularly regarding programmed cell death protein 1 (PD-1)/programmed death-ligand 1 blockades, the clinical outcomes in non-small cell lung cancer (NSCLC) remain variable with limited predictive biomarkers currently available. The present study investigated respiratory microbiota diversity as a potential biomarker to predict the efficacy of PD-1 blockades in patients with advanced NSCLC. A retrospective analysis was conducted on 60 patients treated with PD-1 blockades from May 2019 to May 2023. Clinical data were collected and respiratory microbiota from deep induced sputum specimens were analyzed using 16S rRNA gene sequencing. An index of respiratory microbiota α diversity was applied and exploratory analysis was performed accordingly. The objective response rate (ORR) and disease control rate among the 60 patients receiving PD-1 blockades was 23.3% (95% CI, 13.4-36.0%) and 58.3% (95% CI, 44.9-70.9%), respectively. Analysis of prognostic data of patients with advanced NSCLC receiving PD-1 blockades monotherapy demonstrated a median progression-free survival of 3.4 months (95% CI, 2.54-4.26) and a median overall survival (OS) of 12.3 months (95% CI, 6.29-18.31). Patients were stratified into high and low α diversity groups based on the Shannon diversity index of respiratory microbiota. The ORR was increased in the high diversity group (26.7%) compared with that of the low diversity group (20.0%), although the difference was not statistically significant (P=0.542). Notably, the high diversity group demonstrated a longer median PFS (3.9 vs. 2.8 months; P=0.017) and median OS (16.8 vs. 6.8 months; P=0.016) compared with that of the low diversity group. These findings suggested that PD-1 blockades demonstrate promising therapeutic activity for patients with previously treated advanced NSCLC in clinical practice. Respiratory microbiota α diversity might serve as a potential biomarker to predict the efficacy of PD-1 blockades monotherapy in patients with advanced NSCLC in the future. Therefore, further prospective studies are warranted to validate these findings and to explore the underlying mechanisms by which respiratory microbiota might modulate the immune response to cancer therapy.

Gut microbiota reshapes the TNBC immune microenvironment: Emerging immunotherapeutic strategies

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited treatment options and poor prognosis. The gut microbiota, a diverse community of microorganisms in the gastrointestinal tract, plays a crucial role in regulating immune responses through the gut-immune axis. Recent studies have highlighted its significant impact on TNBC progression and the efficacy of immunotherapies. This review examines the interactions between gut microbiota and the immune system in TNBC, focusing on key immune cells and pathways involved in tumor immunity. It also explores microbiota modulation strategies, including probiotics, prebiotics, dietary interventions, and fecal microbiota transplantation, as potential methods to enhance immunotherapeutic outcomes. Understanding these mechanisms offers promising avenues for improving treatment efficacy and patient prognosis in TNBC.

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.

Gut microbiome associated with PARP inhibitor efficacy in patients with ovarian cancer

OBJECTIVE

To investigate an association between the gut microbiome and efficacy of poly(ADP-ribose) polymerase inhibitors (PARPi) in ovarian cancer.

METHODS

This study conducted fecal microbiome analysis (16S rRNA gene sequencing) and circulating tumor DNA (ctDNA) profiling for ovarian cancer patients who underwent PARPi maintenance therapy. Fecal and blood samples were collected at the baseline and the progressive disease (PD) or last follow-up. The relative abundance of gut microbes and progression-free survival (PFS) were analyzed using linear discriminant analysis of effect size and the Cox proportional hazard model according to BRCA1/2 mutation (BRCA1/2mut) status detected by ctDNA sequencing.

RESULTS

Baseline samples were available from 23 BRCA1/2mut-positive patients and 33 BRCA1/2mut-negative patients. The microbes enriched in the baseline samples with long PFS were Bifidobacterium, Roseburia, Dialister, Butyricicoccus, and Bilophila for BRCA1/2mut-positive patients and Phascolarctobacterium for BRCA1/2mut-negative patients. In multivariate analyses dividing patients by the median values of relative abundances, no bacteria were associated with PFS in BRCA1/2mut-positive patients, whereas high Phascolarctobacterium abundances (≥1.11%) was significantly associated with longer PFS in BRCA1/2mut-negative patients (median 14.0 vs. 5.9 months, hazard ratio=0.28; 95% confidence interval=0.11-0.69; p=0.014). In the last samples, the relative abundances of Phascolarctobacterium were significantly higher in patients without PD (n=5) than those with PD (n=15) (median 1.25% vs. 0.06%; p=0.016).

CONCLUSION

High fecal composition of Phascolarctobacterium was associated with prolonged PFS in patients with BRCA1/2mut-negative ovarian cancer receiving PARPi therapy. Our results would provide new insights for future research.

Advances in Engineered Phages for Disease Treatment

Phage therapy presents a promising solution for combating multidrug-resistant (MDR) bacterial infections and other bacteria-related diseases, attributed to their innate ability to target and lyse bacteria. Recent clinical successes, particularly in treating MDR-related respiratory and post-surgical infections, validated the therapeutic potential of phage therapy. However, the complex microenvironment within the human body poses significant challenges to phage activity and efficacy in vivo. To overcome these barriers, recent advances in phage engineering have aimed to enhance targeting accuracy, improve stability and survivability, and explore synergistic combinations with other therapeutic modalities. This review provides a comprehensive overview of phage therapy, emphasizing the application of engineered phages in antibacterial therapy, tumor therapy, and vaccine development. Furthermore, the review highlights the current challenges and future trends for advancing phage therapy toward broader clinical applications.

Dysbiosis in the Gut Microbiome of Pembrolizumab-Treated Non-Small Lung Cancer Patients Compared to Healthy Controls Characterized Through Opportunistic Sampling

BACKGROUND

The gut microbiome influences the host immune system, cancer development and progression, as well as the response to immunotherapy during cancer treatment. Here, we analyse the composition of the gut bacteriome in metastatic Non-Small Cell Lung Cancer (NSCLC) patients receiving Pembrolizumab immunotherapy within a prospective maintenance trial through opportunistic sampling during treatment.

METHODS

The gut microbiome profiles of NSCLC patients were obtained from stool samples collected during Pembrolizumab treatment and analysed with 16S rRNA metagenomics sequencing. Patient profiles were compared to a group of healthy individuals of matching ethnic group, age, sex, BMI and comorbidities.

RESULTS

A significant decrease in the treated patients was observed in two prominent bacterial families of the phylum Firmicutes, Lachnospiraceae and Ruminoccocaceae, which comprised 31.6% and 21.8% of the bacteriome in the healthy group but only 10.9% and 14.2% in the treated patient group, respectively. Species within the Lachnospiraceae and Ruminococcaceae families are known to break down undigested carbohydrates generating short chain fatty acids (SCFA), such as butyrate, acetate and propionate as their major fermentation end-products, which have been implicated in modifying host immune responses. In addition, a significant increase of the Bacteroidacaeae family (Bacteroidetes phylum) was observed from 10.7% in the healthy group to 23.3% in the treated patient group. Moreover, and in agreement with previous studies, a decrease in the Firmicutes to Bacteroidetes ratio in the metastatic NSCLC Pembrolizumab-treated patients was observed.

CONCLUSION

The observed differences indicate dysbiosis and a compromised intestinal health status in the metastatic NSCLC Pembrolizumab-treated patients. This data could inform future studies of immunotherapy treatment responses and modulation of the gut microbiome to minimise dysbiosis prior or concurrent to treatment.

TRIAL REGISTRATION

SWIPE Trial (NCT02705820).

Enhancing Colorectal Cancer Treatment: The Role of Bifidobacterium in Modulating Gut Immunity and Mitigating Capecitabine-Induced Toxicity

Colorectal cancer (CRC) is the third leading cause of cancer-related mortality globally and presents significant challenges in treatment and patient care. Capecitabine, a widely used prodrug of 5-fluorouracil (5-FU), offers targeted delivery with reduced systemic toxicity compared to traditional chemotherapies. However, capacitabine is associated with adverse effects, such as hand-foot syndrome, gastrointestinal issues, and mucositis. Emerging evidence suggests that probiotics, particularly Bifidobacterium, play a pivotal role in gut microbiota modulation, promoting anti-inflammatory cytokines and short-chain fatty acids, such as butyrate, which possess both intestinal protective and anti-cancer properties. In this review, we explored the potential of Bifidobacterium to improve chemotherapy outcomes by mitigating inflammation and enhancing mucosal immunity in CRC patients. Furthermore, we demonstrated in silico approaches, including molecular docking and protein-protein interaction analysis, for Bifidobacterium and Toll-like receptor 2 (TLR-2), a key mediator of intestinal immunity. Docking results revealed strong binding affinity, suggesting the activation of anti-inflammatory pathways. Notably, this interaction enhanced IL-10 production while reducing pro-inflammatory cytokines, such as IL-6 and TNF-α, fostering gut homeostasis and mitigating chronic inflammation, a key driver of CRC progression. Therefore, future research should focus on personalized probiotics and validating their synergy with chemotherapy and immunotherapy to improve CRC treatment outcomes.

Cancer immune evasion, immunoediting and intratumour heterogeneity

Cancers can avoid immune-mediated elimination by acquiring traits that disrupt antitumour immunity. These mechanisms of immune evasion are selected and reinforced during tumour evolution under immune pressure. Some immunogenic subclones are effectively eliminated by antitumour T cell responses (a process known as immunoediting), which results in a clonally selected tumour. Other cancer cells arise to resist immunoediting, which leads to a tumour that includes several distinct cancer cell populations (referred to as intratumour heterogeneity (ITH)). Tumours with high ITH are associated with poor patient outcomes and a lack of responsiveness to immune checkpoint blockade therapy. In this Review, we discuss the different ways that cancer cells evade the immune system and how these mechanisms impact immunoediting and tumour evolution. We also describe how subclonal antigen presentation in tumours with high ITH can result in immune evasion.

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.

The combination of flaxseed lignans and PD-1/ PD-L1 inhibitor inhibits breast cancer growth via modulating gut microbiome and host immunity

BACKGROUND

Patients with breast cancer (BC) who benefit from the PD-1/PD-L1 inhibitor (PDi) is limited, necessitating novel strategies to improve immunotherapy efficacy of BC. Here we aimed to investigate the inhibitory effects of flaxseed lignans (FL) on the biological behaviors of BC and evaluate the roles of FL in enhancing the anticancer effects of PDi.

METHODS

HPLC was used to detect the content of enterolactone (ENL), the bacterial transformation product of FL. Transcript sequencing was performed and identified CD38 as a downstream target gene of ENL. CD38-overexpressing cells were constructed and cell proliferation, colony formation, wound healing and transwell assays were used to assess the function of ENL/CD38 axis on BC cells in vitro. Multiplexed immunohistochemistry (mIHC) and CyTOF were used to detect the changes of the tumor immune microenvironment (TIM). 16S rDNA sequencing was used to explore the changes of gut microbiota in mice. A series of in vivo experiments were conducted to investigate the anticancer effects and mechanisms of FL and PDi.

RESULTS

FL was converted to ENL by gut microbiota and FL administration inhibited the progression of BC. ENL inhibited the malignant behaviors of BC by downregulating CD38, a key gene associated with immunosuppression and PD-1/PD-L1 blockade resistance. The mIHC assay revealed that FL administration enhanced CD3+, CD4+ and CD8+ cells and reduced F4/80+ cells in TIM. CyTOF confirmed the regulatory effects of FL and FL in combination with PDi (FLcPDi) on TIM. In addition, 16S rDNA analysis demonstrated that FLcPDi treatment significantly elevated the abundance of Akkermansia and, importantly, Akkermansia administration enhanced the response to PDi in mice treated with antibiotics.

CONCLUSIONS

The FL/ENL/CD38 axis inhibited BC progression. FL enhanced the anticancer effects of PDi by modulating gut microbiota and host immunity.

Microbiome Landscape and Association with Response to Immune Checkpoint Inhibitors in Advanced Solid Tumors: A SCRUM-Japan MONSTAR-SCREEN Study

Although the gut microbiome is associated with cancer development and progression, little is known about the effects of the gut microbiome landscape and the efficacy of immune checkpoint inhibitors (ICI) across cancer types. We investigated the association between the microbiome, clinical features, and ICI efficacy across cancer types in a large nationwide screening project for solid tumors. Among 2,180 patients with advanced solid tumors enrolled in the SCRUM-Japan MONSTAR-SCREEN between October 2019 and September 2021, in the chemotherapy-naïve cohort (n = 817), a high prevalence of oral bacteria was observed in patients using proton pump inhibitors (PPI) and those with upper gastrointestinal cancers, particularly postoperative patients with gastric or pancreatic cancer. Among patients treated with ICIs (n = 333), a high abundance of sequence variants in the gut microbiome was not significantly associated with ICI efficacy across cancer types (HR = 0.94; 95% confidence interval, 0.73-1.21). However, high oral bacteria in feces significantly correlated with a shorter progression-free survival compared with low oral bacteria (median, 4.34 vs. 6.97 months; HR = 1.38; 95% confidence interval, 1.07-1.78). Notably, in patients using PPIs, a higher proportion of oral bacteria influenced progression-free survival outcomes of ICI treatment (median, 3.15 vs. 2.04 months; P = 0.08), unlike in PPI nonusers (median, 7.13 vs. 5.55 months; P = 0.74). This study of the gut microbiome has unveiled significant insights into its landscape and potential impact on ICI efficacy. It highlights that the abundance of oral bacteria in feces may play a critical role in diminishing ICI efficacy among patients using PPIs.

SIGNIFICANCE

As part of the MONSTAR-SCREEN, a prospective nationwide project for patients with solid tumors, we found that although gut microbiome diversity does not consistently predict ICI efficacy across cancer types, a high level of oral bacteria in the gut is linked to reduced ICI effectiveness, especially in patients using PPIs. These findings highlight the potential clinical impact of microbiome variations on cancer treatment outcomes.

Global genetic diversity of human gut microbiome species is related to geographic location and host health

The human gut harbors thousands of microbial species, each exhibiting significant inter-individual genetic variability. Although many studies have associated microbial relative abundances with human-health-related phenotypes, the substantial intraspecies genetic variability of gut microbes has not yet been comprehensively considered, limiting the potential of linking such genetic traits with host conditions. Here, we analyzed 32,152 metagenomes from 94 microbiome studies across the globe to investigate the human microbiome intraspecies genetic diversity. We reconstructed 583 species-specific phylogenies and linked them to geographic information and species' horizontal transmissibility. We identified 484 microbial-strain-level associations with 241 host phenotypes, encompassing human anthropometric factors, biochemical measurements, diseases, and lifestyle. We observed a higher prevalence of a Ruminococcus gnavus clade in nonagenarians correlated with distinct plasma bile acid profiles and a melanoma and prostate-cancer-associated Collinsella clade. Our large-scale intraspecies genetic analysis highlights the relevance of strain diversity as it relates to human health.