The commensal microbiome is associated with anti-PD-1 efficacy in metastatic melanoma patients

Prognostic Factors of Platinum-Refractory Advanced Urothelial Carcinoma Treated with Pembrolizumab

INTRODUCTION

Immune checkpoint inhibitor (ICI) therapy has significantly improved the prognosis of some patients with advanced urothelial carcinoma (UC), but it does not provide high therapeutic efficacy in all patients. Therefore, identifying predictive biomarkers is crucial in determining which patients are candidates for ICI treatment. This study aimed to identify the predictors of ICI treatment response in patients with platinum-refractory advanced UC treated with pembrolizumab.

METHODS

Patients with platinum-refractory advanced UC who had received pembrolizumab at two hospitals in Japan were included. Univariate and multivariate analyses were performed to identify biomarkers for progression-free survival (PFS) and overall survival (OS).

RESULTS

Forty-one patients were evaluable for this analysis. Their median age was 75 years, and the vast majority of the patients were male (85.4%). The objective response rate was 29.3%, with a median overall survival (OS) of 17.8 months. On multivariate analysis, an Eastern Cooperative Oncology Group performance status (ECOG-PS) ≥ 2 (HR = 6.33, p = 0.03) and a baseline neutrophil-to-lymphocyte ratio (NLR) > 3 (HR = 2.79, p = 0.04) were significantly associated with poor OS. Antibiotic exposure did not have a significant impact on either PFS or OS.

CONCLUSIONS

ECOG-PS ≥ 2 and baseline NLR > 3 were independent risk factors for OS in patients with platinum-refractory advanced UC treated with pembrolizumab. Antibiotic exposure was not a predictor of ICI treatment response.

Exploring the Role of the Gut and Intratumoral Microbiomes in Tumor Progression and Metastasis

Cancer cell dissemination involves invasion, migration, resistance to stressors in the circulation, extravasation, colonization, and other functions responsible for macroscopic metastases. By enhancing invasiveness, motility, and intravasation, the epithelial-to-mesenchymal transition (EMT) process promotes the generation of circulating tumor cells and their collective migration. Preclinical and clinical studies have documented intensive crosstalk between the gut microbiome, host organism, and immune system. According to the findings, polymorphic microbes might play diverse roles in tumorigenesis, cancer progression, and therapy response. Microbial imbalances and changes in the levels of bacterial metabolites and toxins promote cancer progression via EMT and angiogenesis. In contrast, a favorable microbial composition, together with microbiota-derived metabolites, such as short-chain fatty acids (SCFAs), can attenuate the processes of tumor initiation, disease progression, and the formation of distant metastases. In this review, we highlight the role of the intratumoral and gut microbiomes in cancer cell invasion, migration, and metastatic ability and outline the potential options for microbiota modulation. As shown in murine models, probiotics inhibited tumor development, reduced tumor volume, and suppressed angiogenesis and metastasis. Moreover, modulation of an unfavorable microbiome might improve efficacy and reduce treatment-related toxicities, bringing clinical benefit to patients with metastatic cancer.

Microbiota configuration determines nutritional immune optimization

Mild or transient dietary restriction (DR) improves many aspects of health and aging. Emerging evidence from us and others has demonstrated that DR also optimizes the development and quality of immune responses. However, the factors and mechanisms involved remain to be elucidated. Here, we propose that DR-induced optimization of immunological memory requires a complex cascade of events involving memory T cells, the intestinal microbiota, and myeloid cells. Our findings suggest that DR enhances the ability of memory T cells to recruit and activate myeloid cells in the context of a secondary infection. Concomitantly, DR promotes the expansion of commensal Bifidobacteria within the large intestine, which produce the short-chain fatty acid acetate. Acetate conditioning of the myeloid compartment during DR enhances the capacity of these cells to kill pathogens. Enhanced host protection during DR is compromised when Bifidobacteria expansion is prevented, indicating that microbiota configuration and function play an important role in determining immune responsiveness to this dietary intervention. Altogether, our study supports the idea that DR induces both memory T cells and the gut microbiota to produce distinct factors that converge on myeloid cells to promote optimal pathogen control. These findings suggest that nutritional cues can promote adaptation and co-operation between multiple immune cells and the gut microbiota, which synergize to optimize immunity and protect the collective metaorganism.

Targeting the epigenome to reinvigorate T cells for cancer immunotherapy

Cancer immunotherapy using immune-checkpoint inhibitors (ICIs) has revolutionized the field of cancer treatment; however, ICI efficacy is constrained by progressive dysfunction of CD8+ tumor-infiltrating lymphocytes (TILs), which is termed T cell exhaustion. This process is driven by diverse extrinsic factors across heterogeneous tumor immune microenvironment (TIME). Simultaneously, tumorigenesis entails robust reshaping of the epigenetic landscape, potentially instigating T cell exhaustion. In this review, we summarize the epigenetic mechanisms governing tumor microenvironmental cues leading to T cell exhaustion, and discuss therapeutic potential of targeting epigenetic regulators for immunotherapies. Finally, we outline conceptual and technical advances in developing potential treatment paradigms involving immunostimulatory agents and epigenetic therapies.

Extracellular vesicles hybrid plasmid-loaded lipid nanovesicles for synergistic cancer immunotherapy

Combination immunotherapy of cancer vaccines with immune checkpoint inhibitors (ICIs) represents a promising therapeutic strategy for immunosuppressed and cold tumors. However, this strategy still faces challenges, including the limited therapeutic efficacy of cancer vaccines and immune-related adverse events associated with systematic delivery of ICIs. Herein, we demonstrate the antitumor immune response induced by outer membrane vesicle from Akkermansia muciniphila (Akk-OMV), which exhibites a favorable safety profile, highlighting the potential application as a natural and biocompatible self-adjuvanting vesicle. Utilizing tumor cell-derived exosome as an antigen source and Akk-OMV as a natural adjuvant, we construct a cancer vaccine formulation of extracellular vesicles hybrid lipid nanovesicles (Lipo@HEV) for enhanced prophylactic and therapeutic vaccination by promoting dendritic cell (DC) maturation in lymph node and activating cytotoxic T cell (CTL) response. The Lipo@HEV is further loaded with plasmid to enable gene therapy-mediated PD-L1 blockade upon peritumoral injection. Meanwhile, it penetrates into lymph node to initiate DC maturation and CTL activation, synergistically inhibiting the established tumor. The fabrication of extracellular vesicles hybrid plasmid-loaded lipid nanovesicles reveals a promising gene therapy-guided and vesicle-based hybrid system for therapeutic cancer vaccination and synergistic immunotherapy strategy.

The Effects of Antibiotics on the Development and Treatment of Non-Small Cell Lung Cancer

There have been studies on antibiotic use concerning lung cancer and its potential impact on carcinogenesis and microbiome. However, subsequent research has failed to support these associations consistently. In terms of the potential carcinogenic of antibiotics on lung cancer, the available evidence has not been sufficient to draw any definitive conclusions. Maintaining immune homeostasis and preventing pathogen invasion is critically dependent on the microbiome. The subtle balance of the body microbiota, including the lungs, is susceptible to disruption by antibiotic use. There is an association between disruptions of the lung microbiome and respiratory diseases, including lung cancer, and decreased efficacy of treatments. Patients with lung cancer are often indicated for antibiotic treatment due to respiratory infections or other comorbidities. Pulmonary infections in the area of undetected lung tumors are not uncommon. They can be an early sign of malignancy, which may explain the association between antibiotic use and lung cancer diagnosis. Antibiotic use can also affect the effectiveness of immune checkpoint inhibitor therapy. Studies suggest that antibiotic use can impair the efficacy of immune checkpoint inhibitor therapy in lung cancer patients, particularly around the time when treatment is initiated. These findings require further study, understanding underlying mechanisms, and identifying microbiota signatures associated with treatment response.

Microbiota: A key factor affecting and regulating the efficacy of immunotherapy

BACKGROUND

Immunotherapy has made significant progress in cancer treatment; however, the responsiveness to immunotherapy varies widely among patients. Growing evidence has demonstrated the role of the gut microbiota in the efficacy of immunotherapy.

MAIN BODY

Herein, we summarise the changes in the microbiota in different cancers under various immunotherapies. The microbial-host signal transmission on immunotherapeutic responses and mechanisms associated with microbial translocation to tumours in the context of immunotherapy are also discussed. In addition, we have highlighted the clinical application value of methods for regulating the microbiota. Finally, we elaborate on the relationship between the microbiota, host and immunotherapy, and provide potential directions for future research.

CONCLUSION

Different microbiota cause changes in the tumour microenvironment through microbial signals thereby affecting immunotherapy efficacy. Translocation of gut microbiota and the role of extraintestinal microbiota in immunotherapy deserve attention. Microbiota regulation is a novel strategy for combination therapy with immunotherapy. Although there are several aspects that deserve further refinement and exploration with regard to administration and clinical translation. Nevertheless, it is foreseeable that the microbiota will become an integral part of cancer treatment.

Effect of synbiotic supplementation on immune parameters and gut microbiota in healthy adults: a double-blind randomized controlled trial

Synbiotics are increasingly used by the general population to boost immunity. However, there is limited evidence concerning the immunomodulatory effects of synbiotics in healthy individuals. Therefore, we conducted a double-blind, randomized, placebo-controlled study in 106 healthy adults. Participants were randomly assigned to receive either synbiotics (containing Bifidobacterium lactis HN019 1.5 × 108 CFU/d, Lactobacillus rhamnosus HN001 7.5 × 107 CFU/d, and fructooligosaccharide 500 mg/d) or placebo for 8 weeks. Immune parameters and gut microbiota composition were measured at baseline, mid, and end of the study. Compared to the placebo group, participants receiving synbiotic supplementation exhibited greater reductions in plasma C-reactive protein (P = 0.088) and interferon-gamma (P = 0.008), along with larger increases in plasma interleukin (IL)-10 (P = 0.008) and stool secretory IgA (sIgA) (P = 0.014). Additionally, synbiotic supplementation led to an enrichment of beneficial bacteria (Clostridium_sensu_stricto_1, Lactobacillus, Bifidobacterium, and Collinsella) and several functional pathways related to amino acids and short-chain fatty acids biosynthesis, whereas reduced potential pro-inflammatory Parabacteroides compared to baseline. Importantly, alternations in anti-inflammatory markers (IL-10 and sIgA) were significantly correlated with microbial variations triggered by synbiotic supplementation. Stratification of participants into two enterotypes based on pre-treatment Prevotella-to-Bacteroides (P/B) ratio revealed a more favorable effect of synbiotic supplements in individuals with a higher P/B ratio. In conclusion, this study suggested the beneficial effects of synbiotic supplementation on immune parameters, which were correlated with synbiotics-induced microbial changes and modified by microbial enterotypes. These findings provided direct evidence supporting the personalized supplementation of synbiotics for immunomodulation.

Lifestyle and host determinants of antitumor immunity and cancer health disparities

Lifestyle factors exert profound effects on host physiology and immunology. Disparities in cancer outcomes persist as a complex and multifaceted challenge, necessitating a comprehensive understanding of the interplay between host environment and antitumor immune responses. Determinants of health - such as obesity, diet, exercise, stress, or sleep disruption - have the potential for modification, yet some exert long-lasting effects and may challenge the notion of complete reversibility. Herein we review intersectional considerations of lifestyle immunity and the impact on tumor immunology and disparities in cancer outcomes, with a focus on obesity.

Microbiota Diversity in Non-Small Cell Lung Cancer Gut and Mouth Cavity Microbiota Diversity in Non-Small Cell Lung Cancer Patients

Lung malignancies have a substantial impact on cancer incidence and mortality worldwide. Even though many factors involved in the development of the disease are known, many questions remain unanswered. Previous studies suggest that the intestinal microbiota may have a role in developing malignant diseases. According to some findings, the microbiota has proven to be a key modulator of carcinogenic processes and the immune response against cancer cells, potentially influencing the effectiveness of immunotherapy. In our study, we characterized culturable microorganisms associated with non-small cell lung cancer (NSCLC) that can be recovered from rectal swabs and mouthwash. In addition, we also explored differences in the culturable microbiota with two main types of NSCLC - adenocarcinoma (ADC) and squamous cell carcinoma (SCC). With 141 patients included in the study (86 ADC and 55 SCC cases), a significant difference was observed between the two types in seven bacterial species (Collinsella, Corynebacterium, Klebsiella, Lactobacillus, Neisseria, Rothia, and Streptococcus), including the site of origin. The relationship between microbial dysbiosis and lung cancer is poorly understood; future research could shed light on the links between gut microbiota and lung cancer development.

GlcNac produced by the gut microbiome enhances host influenza resistance by modulating NK cells

Microbiota are known to modulate the host response to influenza infection, but the mechanisms remain largely unknown. Gut metabolites are the key mediators through which gut microbes play anti-influenza effect. Transferring fecal metabolites from mice with high influenza resistance into antibiotic-treated recipient mice conferred resistance to influenza infections. By comparing the metabolites of different individuals with high or low influenza resistance, we identified and validated N-acetyl-D-glucosamine (GlcNAc) and adenosine showed strong positive correlations with influenza resistance and exerted anti-influenza effects in vivo or in vitro, respectively. Especially, GlcNAc mediated the anti-influenza effect by increasing the proportion and activity of NK cells. Several gut microbes, including Clostridium sp., Phocaeicola sartorii, and Akkermansia muciniphila, were positively correlated with influenza resistance, and can upregulate the level of GlcNAc in the mouse gut by exogenous supplementation. Subsequent studies confirmed that administering a combination of the three bacteria to mice via gavage resulted in similar modulation of NK cell responses as observed with GlcNAc. This study demonstrates that gut microbe-produced GlcNAc protects the host against influenza by regulating NK cells, facilitating the elucidation of the action mechanism of gut microbes mediating host influenza resistance.

Assessment of intestinal status in MPLW515L mutant myeloproliferative neoplasms mice model

The MPLW515L mutation is a prevalent genetic mutation in patients with myeloproliferative neoplasms (MPN), and utilizing this mutation in mice model can provide important insights into the disease. However, the relationship between intestinal homeostasis and MPN mice model remains elusive. In this study, we utilized a retroviral vector to transfect hematopoietic stem cells with the MPLW515L mutation, creating mutated MPN mice model to investigate their intestinal status. Our results revealed that the MPLW515L in MPN mice model aggravated inflammation in the intestines, decreased the levels of tight junction proteins and receptors for bacteria metabolites. Additionally, there was increased activation of the caspase1/IL-1β signaling pathway and a significant reduction in phos-p38 levels in the intestinal tissue in MPN mice. The MPLW515L mutation also led to up-expression of anti-microbial genes in the intestinal tract. Though the mutation had no impact on the alpha diversity and dominant bacterial taxa, it did influence the rare bacterial taxa/sub-communities and consequently impacted intestinal homeostasis. Our findings demonstrate the significance of MPLW515L mice model for studying MPN disease and highlight the mutation's influence on intestinal homeostasis, including inflammation, activation of the IL-1β signaling pathway, and the composition of gut microbial communities.

Pharmacomicrobiomics of cell-cycle specific anti-cancer drugs - is it a new perspective for personalized treatment of cancer patients?

Intestinal bacteria are equipped with an enzyme apparatus that is involved in the active biotransformation of xenobiotics, including drugs. Pharmacomicrobiomics, a new area of pharmacology, analyses interactions between bacteria and xenobiotics. However, there is another side to the coin. Pharmacotherapeutic agents can significantly modify the microbiota, which consequently affects their efficacy. In this review, we comprehensively gathered scientific evidence on the interplay between anticancer therapies and gut microbes. We also underlined how such interactions might impact the host response to a given therapy. We discuss the possibility of modulating the gut microbiota to increase the effectiveness/decrease the incidence of adverse events during tumor therapy. The anticipation of the future brings new evidence that gut microbiota is a target of interest to increase the efficacy of therapy.

The potential role of the microbiota in prostate cancer pathogenesis and treatment

The human body hosts a complex and dynamic population of trillions of microorganisms - the microbiota - which influences the body in homeostasis and disease, including cancer. Several epidemiological studies have associated specific urinary and gut microbial species with increased risk of prostate cancer; however, causal mechanistic data remain elusive. Studies have associated bacterial generation of genotoxins with the occurrence of TMPRSS2-ERG gene fusions, a common, early oncogenic event during prostate carcinogenesis. A subsequent study demonstrated the role of the gut microbiota in prostate cancer endocrine resistance, which occurs, at least partially, through the generation of androgenic steroids fuelling oncogenic signalling via the androgen receptor. These studies present mechanistic evidence of how the host microbiota might be implicated in prostate carcinogenesis and tumour progression. Importantly, these findings also reveal potential avenues for the detection and treatment of prostate cancer through the profiling and modulation of the host microbiota. The latter could involve approaches such as the use of faecal microbiota transplantation, prebiotics, probiotics, postbiotics or antibiotics, which can be used independently or combined with existing treatments to reverse therapeutic resistance and improve clinical outcomes in patients with prostate cancer.

Statistical normalization methods in microbiome data with application to microbiome cancer research

Mounting evidence has shown that gut microbiome is associated with various cancers, including gastrointestinal (GI) tract and non-GI tract cancers. But microbiome data have unique characteristics and pose major challenges when using standard statistical methods causing results to be invalid or misleading. Thus, to analyze microbiome data, it not only needs appropriate statistical methods, but also requires microbiome data to be normalized prior to statistical analysis. Here, we first describe the unique characteristics of microbiome data and the challenges in analyzing them (Section 2). Then, we provide an overall review on the available normalization methods of 16S rRNA and shotgun metagenomic data along with examples of their applications in microbiome cancer research (Section 3). In Section 4, we comprehensively investigate how the normalization methods of 16S rRNA and shotgun metagenomic data are evaluated. Finally, we summarize and conclude with remarks on statistical normalization methods (Section 5). Altogether, this review aims to provide a broad and comprehensive view and remarks on the promises and challenges of the statistical normalization methods in microbiome data with microbiome cancer research examples.

Microbial metabolite butyrate promotes anti-PD-1 antitumor efficacy by modulating T cell receptor signaling of cytotoxic CD8 T cell

Recent studies have demonstrated that the antitumor immunity of immune cells can be modulated by gut microbiota and their metabolites. However, the underlying mechanisms remain unclear. Here, we showed that the serum butyric acid level is positively correlated with the expression of programmed cell death-1 (PD-1) on circulating CD8+ and Vγ9 Vδ2 (Vδ2+) T cells in patients with non-small cell lung cancer (NSCLC). Responder NSCLC patients exhibited higher levels of serum acetic acid, propionic acid, and butyric acid than non-responders. Depletion of the gut microbiota reduces butyrate levels in both feces and serum in tumor-bearing mice. Mechanistically, butyrate increased histone 3 lysine 27 acetylation (H3K27ac) at the promoter region of Pdcd1 and Cd28 in human CD8+ T cells, thereby promoting the expression of PD-1/CD28 and enhancing the efficacy of anti-PD-1 therapy. Butyrate supplementation promotes the expression of antitumor cytokines in cytotoxic CD8+ T cells by modulating the T-cell receptor (TCR) signaling pathway. Collectively, our findings reveal that the metabolite butyrate of the gut microbiota facilitates the efficacy of anti-PD-1 immunotherapy by modulating TCR signaling of cytotoxic CD8 T cells, and is a highly promising therapeutic biomarker for enhancing antitumor immunity.

Fecal microbiota transplantation plus tislelizumab and fruquintinib in refractory microsatellite stable metastatic colorectal cancer: an open-label, single-arm, phase II trial (RENMIN-215)

Background

Immunotherapy has revolutionized the treatment of cancer. However, microsatellite stable (MSS) metastatic colorectal cancer (mCRC) shows a low response to PD-1 inhibitors. Antiangiogenic therapy can enhance anti-PD-1 efficacy, but it still cannot meet clinical needs. Increasing evidence supported a close relationship between gut microbiome and anti-PD-1 efficacy. This study aimed to explore the efficacy and safety of the combination of fecal microbiota transplantation (FMT) and tislelizumab and fruquintinib in refractory MSS mCRC.

Methods

In the phase II trial, MSS mCRC patients were administered FMT plus tislelizumab and fruquintinib as a third-line or above treatment. The primary endpoint was progression-free survival (PFS). Secondary endpoints were overall survival (OS), objective response rate (ORR), disease control rate (DCR), duration of response (DoR), clinical benefit rate (CBR), safety and quality of life. Feces and peripheral blood were collected for exploratory biomarker analysis. This study is registered with Chictr.org.cn, identifier ChiCTR2100046768.

Findings

From May 10, 2021 to January 17, 2022, 20 patients were enrolled. Median follow-up was 13.7 months. Median PFS was 9.6 months (95% CI 4.1-15.1). Median OS was 13.7 months (95% CI 9.3-17.7). Median DoR was 8.1 months (95% CI 1.7-10.6). ORR was 20% (95% CI 5.7-43.7). DCR was 95% (95% CI 75.1-99.9). CBR was 60% (95% CI 36.1-80.9). Nineteen patients (95%) experienced at least one treatment-related adverse event (TRAE). Six patients (30%) had grade 3-4 TRAEs, with the most common being albuminuria (10%), urine occult blood (10%), fecal occult blood (10%), hypertension (5%), hyperglycemia (5%), liver dysfunction (5%), hand-foot skin reaction (5%), and hypothyroidism (5%). No treatment-related deaths occurred. Responders had a high-abundance of Proteobacteria and Lachnospiraceae family and a low-abundance of Actinobacteriota and Bifidobacterium. The treatment did not change the structure of peripheral blood TCR repertoire. However, the expanded TCRs exhibited the characteristics of antigen-driven responses in responders.

Interpretation

FMT plus tislelizumab and fruquintinib as third-line or above treatment showed improved survival and manageable safety in refractory MSS mCRC, suggesting a valuable new treatment option for this patient population.

Funding

This study was supported by the National Natural Science Foundation of China (82102954 to Wensi Zhao) and the Special Project of Central Government for Local Science and Technology Development of Hubei Province (ZYYD2020000169 to Yongshun Chen).

Bifidobacterium mechanisms of immune modulation and tolerance

Bifidobacterium is a widely distributed commensal bacterial genus that displays beneficial pro-homeostatic and anti-inflammatory immunomodulatory properties. Depletion or absence of Bifidobacterium in humans and model organisms is associated with autoimmune responses and impaired immune homeostasis. At the cellular level, Bifidobacterium upregulates suppressive regulatory T cells, maintains intestinal barrier function, modulates dendritic cell and macrophage activity, and dampens intestinal Th2 and Th17 programs. While there has been a large volume of literature characterizing the probiotic properties of various Bifidobacterial species, the likely multifactorial mechanisms underlying these effects remain elusive, in particular, its immune tolerogenic effect. However, recent work has shed light on Bifidobacterium surface structural polysaccharide and protein elements, as well as its metabolic products, as commensal mediators of immune homeostasis. This review aims to discuss several mechanisms Bifidobacterium utilizes for immune modulation as well as their indirect impact on the regulation of gut microbiome structure and function, from structural molecules to produced metabolites. These mechanisms are pertinent to an increasingly networked understanding of immune tolerance and homeostasis in health and disease.

Salivary microbiome changes distinguish response to chemoradiotherapy in patients with oral cancer

BACKGROUND

Oral squamous cell carcinoma (SCC) is associated with oral microbial dysbiosis. In this unique study, we compared pre- to post-treatment salivary microbiome in patients with SCC by 16S rRNA gene sequencing and examined how microbiome changes correlated with the expression of an anti-microbial protein.

RESULTS

Treatment of SCC was associated with a reduction in overall bacterial richness and diversity. There were significant changes in the microbial community structure, including a decrease in the abundance of Porphyromonaceae and Prevotellaceae and an increase in Lactobacillaceae. There were also significant changes in the microbial community structure before and after treatment with chemoradiotherapy, but not with surgery alone. In patients treated with chemoradiotherapy alone, several bacterial populations were differentially abundant between responders and non-responders before and after therapy. Microbiome changes were associated with a change in the expression of DMBT1, an anti-microbial protein in human saliva. Additionally, we found that salivary DMBT1, which increases after treatment, could serve as a post-treatment salivary biomarker that links to microbial changes. Specifically, post-treatment increases in human salivary DMBT1 correlated with increased abundance of Gemella spp., Pasteurellaceae spp., Lactobacillus spp., and Oribacterium spp. This is the first longitudinal study to investigate treatment-associated changes (chemoradiotherapy and surgery) in the oral microbiome in patients with SCC along with changes in expression of an anti-microbial protein in saliva.

CONCLUSIONS

The composition of the oral microbiota may predict treatment responses; salivary DMBT1 may have a role in modulating the oral microbiome in patients with SCC. After completion of treatment, 6 months after diagnosis, patients had a less diverse and less rich oral microbiome. Leptotrichia was a highly prevalent bacteria genus associated with disease. Expression of DMBT1 was higher after treatment and associated with microbiome changes, the most prominent genus being Gemella Video Abstract.

Exploring the role of gut microbiota in advancing personalized medicine

Ongoing extensive research in the field of gut microbiota (GM) has highlighted the crucial role of gut-dwelling microbes in human health. These microbes possess 100 times more genes than the human genome and offer significant biochemical advantages to the host in nutrient and drug absorption, metabolism, and excretion. It is increasingly clear that GM modulates the efficacy and toxicity of drugs, especially those taken orally. In addition, intra-individual variability of GM has been shown to contribute to drug response biases for certain therapeutics. For instance, the efficacy of cyclophosphamide depends on the presence of Enterococcus hirae and Barnesiella intestinihominis in the host intestine. Conversely, the presence of inappropriate or unwanted gut bacteria can inactivate a drug. For example, dehydroxylase of Enterococcus faecalis and Eggerthella lenta A2 can metabolize L-dopa before it converts into the active form (dopamine) and crosses the blood-brain barrier to treat Parkinson's disease patients. Moreover, GM is emerging as a new player in personalized medicine, and various methods are being developed to treat diseases by remodeling patients' GM composition, such as prebiotic and probiotic interventions, microbiota transplants, and the introduction of synthetic GM. This review aims to highlight how the host's GM can improve drug efficacy and discuss how an unwanted bug can cause the inactivation of medicine.

Dissecting the Impact of the Gut Microbiome on Cancer Immunotherapy

The gut microbiome has emerged as a key regulator of response to cancer immunotherapy. However, there is a gap in our understanding of the underlying mechanisms by which the microbiome influences immunotherapy. To this end, we developed a mathematical model based on i) gut microbiome data derived from preclinical studies on melanomas after fecal microbiota transplant, ii) mechanistic modeling of antitumor immune response, and iii) robust association analysis of murine and human microbiome profiles with model-predicted immune profiles. Using our model, we could distill the complexity of these murine and human studies on microbiome modulation in terms of just two model parameters: the activation and killing rate constants of immune cells. We further investigated associations between specific bacterial taxonomies and antitumor immunity and immunotherapy efficacy. This model can guide the design of studies to refine and validate mechanistic links between the microbiome and immune system.

TIGIT+ NK cells in combination with specific gut microbiota features predict response to checkpoint inhibitor therapy in melanoma patients

BACKGROUND

Composition of the intestinal microbiota has been correlated to therapeutic efficacy of immune checkpoint inhibitors (ICI) in various cancer entities including melanoma. Prediction of the outcome of such therapy, however, is still unavailable. This prospective, non-interventional study was conducted in order to achieve an integrated assessment of the connection between a specific intestinal microbiota profile and antitumor immune response to immune checkpoint inhibitor therapy (anti-PD-1 and/or anti-CTLA-4) in melanoma patients.

METHODS

We assessed blood and stool samples of 29 cutaneous melanoma patients who received immune checkpoint inhibitor therapy. For functional and phenotypical immune analysis, 12-color flow cytometry and FluoroSpot assays were conducted. Gut microbiome was analyzed with shotgun metagenomics sequencing. To combine clinical, microbiome and immune variables, we applied the Random Forest algorithm.

RESULTS

A total of 29 patients was analyzed in this study, among whom 51.7% (n = 15) reached a durable clinical benefit. The Immune receptor TIGIT is significantly upregulated in T cells (p = 0.0139) and CD56high NK cells (p = 0.0037) of responders. Several bacterial taxa were associated with response (e.g. Ruminococcus torques) or failure (e.g. Barnesiella intestinihominis) to immune therapy. A combination of two microbiome features (Barnesiella intestinihominis and the Enterobacteriaceae family) and one immune feature (TIGIT+ CD56high NK cells) was able to predict response to ICI already at baseline (AUC = 0.85; 95% CI: 0.841-0.853).

CONCLUSIONS

Our results reconfirm a link between intestinal microbiota and response to ICI therapy in melanoma patients and furthermore point to TIGIT as a promising target for future immunotherapies.

Gut microbiota in gastric cancer: A determinant of etiology or a therapeutic approach?

The impact of the gut microbiota on the well-being and pathology of the host has garnered growing interest. In recent times, there has been a surge in understanding the mechanistic connections between the gut microbiota and cancer, particularly in relation to the genesis, progression, and therapeutic approaches for gastric cancer. The dysbiosis of the intestinal microbiome stands as a significant determinant in the etiology of gastric cancer. Currently, a preliminary consensus exists, although the precise mechanism remains incompletely understood. As research progresses, it becomes increasingly evident that intestinal flora significantly contributes to the therapeutic approach for gastric cancer. This paper gives a comprehensive review of the impact of intestinal flora on gastric cancer, examines the role of the intestinal microbiome in the management of gastric cancer, and elucidates the potential of utilizing the intestinal microbiome as an anti-tumor therapy, with an aim to furnish a point of reference and stimulate future research endeavors.

Dietary Lactobacillus rhamnosus GG extracellular vesicles enhance antiprogrammed cell death 1 (anti-PD-1) immunotherapy efficacy against colorectal cancer

There is a need to explore combination therapy to improve the efficacy of immunotherapy for colorectal cancer through food probiotics. In this study, extracellular vesicles (EV) derived from Lactobacillus rhamnosus GG (LGG-EV) were successfully isolated. Adjusting the culture temperature to 30 °C led to an elevated LGG-EV yield, and the addition of penicillin resulted in a decrease in particle size. In addition, LGG-EV have better gastrointestinal tract stability in a Ca2+ environment in vivo and in vitro. Oral administration of LGG-EV synergistically improved anti-PD-1 immunotherapy efficacy against colorectal cancer. Mechanistically, LGG-EV modulated intestinal immunity by increasing the CD8+ T/CD4+ T cell ratio in mesenteric lymph nodes and enhancing the ratio of MHC II+ DC cells, CD4+ T cells, and CD8+ T cells in tumor tissues. Meanwhile, the diversity of the gut microbiota and the abundance of beneficial bacteria, such as Lactobacillus, increased in the combined-treatment mice. In addition, there were significant changes in the levels of serum metabolites associated with the microbiota and anti-tumor effects, including uridine, which was elevated by the combination of anti-PD-1 and LGG-EV treatment. Our findings provide theoretical and mechanistic insights into the development of LGG-EV as postbiotics in combination with immune checkpoint inhibitors for cancer therapy.

Prior antibiotic administration disrupts anti-PD-1 responses in advanced gastric cancer by altering the gut microbiome and systemic immune response

Evidence on whether prior antibiotic (pATB) administration modulates outcomes of programmed cell death protein-1 (PD-1) inhibitors in advanced gastric cancer (AGC) is scarce. In this study, we find that pATB administration is consistently associated with poor progression-free survival (PFS) and overall survival (OS) in multiple cohorts consisting of patients with AGC treated with PD-1 inhibitors. In contrast, pATB does not affect outcomes among patients treated with irinotecan. Multivariable analysis of the overall patients treated with PD-1 inhibitors confirms that pATB administration independently predicts worse PFS and OS. Administration of pATBs is associated with diminished gut microbiome diversity, reduced abundance of Lactobacillus gasseri, and disproportional enrichment of circulating exhaustive CD8+ T cells, all of which are associated with worse outcomes. Considering the inferior treatment response and poor survival outcomes by pATB administration followed by PD-1 blockade, ATBs should be prescribed with caution in patients with AGC who are planning to receive PD-1 inhibitors.

Exogenous Sequences in Tumors and Immune Cells (Exotic): A Tool for Estimating the Microbe Abundances in Tumor RNA-seq Data

The microbiome affects cancer, from carcinogenesis to response to treatments. New evidence suggests that microbes are also present in many tumors, though the scope of how they affect tumor biology and clinical outcomes is in its early stages. A broad survey of tumor microbiome samples across several independent datasets is needed to identify robust correlations for follow-up testing. We created a tool called {exotic} for "exogenous sequences in tumors and immune cells" to carefully identify the tumor microbiome within RNA sequencing (RNA-seq) datasets. We applied it to samples collected through the Oncology Research Information Exchange Network (ORIEN) and The Cancer Genome Atlas. We showed how the processing removes contaminants and batch effects to yield microbe abundances consistent with non-high-throughput sequencing-based approaches and DNA-amplicon-based measurements of a subset of the same tumors. We sought to establish clinical relevance by correlating the microbe abundances with various clinical and tumor measurements, such as age and tumor hypoxia. This process leveraged the two datasets and raised up only the concordant (significant and in the same direction) associations. We observed associations with survival and clinical variables that are cancer specific and relatively few associations with immune composition. Finally, we explored potential mechanisms by which microbes and tumors may interact using a network-based approach. Alistipes, a common gut commensal, showed the highest network degree centrality and was associated with genes related to metabolism and inflammation. The {exotic} tool can support the discovery of microbes in tumors in a way that leverages the many existing and growing RNA-seq datasets.

SIGNIFICANCE

The intrinsic tumor microbiome holds great potential for its ability to predict various aspects of cancer biology and as a target for rational manipulation. Here, we describe a tool to quantify microbes from within tumor RNA-seq and apply it to two independent datasets. We show new associations with clinical variables that justify biomarker uses and more experimentation into the mechanisms by which tumor microbiomes affect cancer outcomes.

The role of microbiota in tumorigenesis, progression and treatment of bladder cancer

For decades, the urinary system was regarded as a sterile environment due to the absence of any bacterial growth in clinical standard urine cultures from healthy individuals. However, a diverse array of microbes colonizes the urinary system in small quantities, exhibiting a variable compositional signature influenced by differences in sex, age, and pathological state. Increasing pieces of evidence suggest microbiota exists in tumor tissue and plays a crucial role in tumor microenvironment based on research in multiple cancer models. Current studies about microbiota and bladder cancer have preliminarily characterized the bladder cancer-related microbiota, but how the microbiota influences the biological behavior of bladder cancer remains unclarified. This review summarizes the characteristics of microbiota in bladder cancer, aims to propose possible mechanisms that microbiota acts in tumorigenesis and progression of bladder cancer based on advances in gut microbiota, and discusses the potential clinical application of microbiota in bladder cancer.

Gut microbial structural variation associates with immune checkpoint inhibitor response

The gut microbiota may have an effect on the therapeutic resistance and toxicity of immune checkpoint inhibitors (ICIs). However, the associations between the highly variable genomes of gut bacteria and the effectiveness of ICIs remain unclear, despite the fact that merely a few gene mutations between similar bacterial strains may cause significant phenotypic variations. Here, using datasets from the gut microbiome of 996 patients from seven clinical trials, we systematically identify microbial genomic structural variants (SVs) using SGV-Finder. The associations between SVs and response, progression-free survival, overall survival, and immune-related adverse events are systematically explored by metagenome-wide association analysis and replicated in different cohorts. Associated SVs are located in multiple species, including Akkermansia muciniphila, Dorea formicigenerans, and Bacteroides caccae. We find genes that encode enzymes that participate in glucose metabolism be harbored in these associated regions. This work uncovers a nascent layer of gut microbiome heterogeneity that is correlated with hosts' prognosis following ICI treatment and represents an advance in our knowledge of the intricate relationships between microbiota and tumor immunotherapy.

Dissecting the role of the gut microbiome and fecal microbiota transplantation in radio- and immunotherapy treatment of colorectal cancer

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers and poses a major burden on the human health worldwide. At the moment, treatment of CRC consists of surgery in combination with (neo)adjuvant chemotherapy and/or radiotherapy. More recently, immune checkpoint blockers (ICBs) have also been approved for CRC treatment. In addition, recent studies have shown that radiotherapy and ICBs act synergistically, with radiotherapy stimulating the immune system that is activated by ICBs. However, both treatments are also associated with severe toxicity and efficacy issues, which can lead to temporary or permanent discontinuation of these treatment programs. There's growing evidence pointing to the gut microbiome playing a role in these issues. Some microorganisms seem to contribute to radiotherapy-associated toxicity and hinder ICB efficacy, while others seem to reduce radiotherapy-associated toxicity or enhance ICB efficacy. Consequently, fecal microbiota transplantation (FMT) has been applied to reduce radio- and immunotherapy-related toxicity and enhance their efficacies. Here, we have reviewed the currently available preclinical and clinical data in CRC treatment, with a focus on how the gut microbiome influences radio- and immunotherapy toxicity and efficacy and if these treatments could benefit from FMT.

Stem Cell Origin of Cancer: Clinical Implications for Cancer Immunity and Immunotherapy

A simple way to understand the immune system is to separate the self from non-self. If it is self, the immune system tolerates and spares. If it is non-self, the immune system attacks and destroys. Consequently, if cancer has a stem cell origin and is a stem cell disease, we have a serious problem and a major dilemma with immunotherapy. Because many refractory cancers are more self than non-self, immunotherapy may become an uphill battle and pyrrhic victory in cancer care. In this article, we elucidate cancer immunity. We demonstrate for whom, with what, as well as when and how to apply immunotherapy in cancer care. We illustrate that a stem cell theory of cancer affects our perspectives and narratives of cancer. Without a pertinent theory about cancer's origin and nature, we may unwittingly perform misdirected cancer research and prescribe misguided cancer treatments. In the ongoing saga of immunotherapy, we are at a critical juncture. Because of the allure and promises of immunotherapy, we will be treating more patients not immediately threatened by their cancer. They may have more to lose than to gain, if we have a misconception and if we are on a wrong mission with immunotherapy. According to the stem cell theory of cancer, we should be careful with immunotherapy. When we do not know or realize that cancer originates from a stem cell and has stem-ness capabilities, we may cause more harm than good in some patients and fail to separate the truth from the myth about immunotherapy in cancer care.

Multi-kingdom gut microbiota analyses define bacterial-fungal interplay and microbial markers of pan-cancer immunotherapy across cohorts

The effect of gut bacteria on the response to immune checkpoint inhibitors (ICIs) has been studied, but the relationship between fungi and ICI responses is not fully understood. Herein, 862 fecal metagenomes from 9 different cohorts were integrated for the identification of differentially abundant fungi and subsequent construction of random forest (RF) models to predict ICI responses. Fungal markers demonstrate excellent performance, with an average area under the curve (AUC) of 0.87. Their performance improves even further, reaching an average AUC of 0.89 when combined with bacterial markers. Higher enrichment of exhausted T cells is detected in responders, as predicted by fungal markers. Multi-kingdom network and functional analysis reveal that the fungus Schizosaccharomyces octosporus may ferment starch into short-chain fatty acids in responders. This study provides a fungal profile of the ICI response and the identification of multi-kingdom microbial markers with good performance that may improve the overall applicability of ICI therapy.

Training the microbiota to increase immune checkpoint blockade and to reduce toxicity

There is no doubt that immunotherapy, particularly immune checkpoint blockade (ICB), has drastically improved treatment of metastatic cancer patients. Microbiota composition has been proposed to be one of the reasons for failure or success. ICB works via the activation or reactivation of T cells that are "switched off" by tumor cells or by the tumor microenvironment. Even advanced metastatic disease, previously considered as untreatable, can benefit from cancer immunotherapy. However, still a good proportion of patients does not respond to therapy or acquires resistance during treatment. Some genera or species of bacteria have been associated with treatment response or toxicity, but as the composition of the microbiota is not static, rather, it is very dynamic there is promise that by changing the microbiota composition, or by harnessing the microbiota 'secrete' tricks, one can improve treatment efficacy or reduce toxicity. Several players, including diet, prebiotics, probiotics, and postbiotics, have been proposed to shape the microbiota. In this minireview, we summarize very recent data on how to train the microbiota to increase ICB efficacy and reduce toxicity.

Bifidobacteria metabolize lactulose to optimize gut metabolites and prevent systemic infection in patients with liver disease

Progression of chronic liver disease is precipitated by hepatocyte loss, inflammation and fibrosis. This process results in the loss of critical hepatic functions, increasing morbidity and the risk of infection. Medical interventions that treat complications of hepatic failure, including antibiotic administration for systemic infections and lactulose treatment for hepatic encephalopathy, can impact gut microbiome composition and metabolite production. Here, using shotgun metagenomic sequencing and targeted metabolomic analyses on 847 faecal samples from 262 patients with acute or chronic liver disease, we demonstrate that patients hospitalized for liver disease have reduced microbiome diversity and a paucity of bioactive metabolites, including short-chain fatty acids and bile acid derivatives, that impact immune defences and epithelial barrier integrity. We find that patients treated with the orally administered but non-absorbable disaccharide lactulose have increased densities of intestinal bifidobacteria and reduced incidence of systemic infections and mortality. Bifidobacteria metabolize lactulose, produce high concentrations of acetate and acidify the gut lumen in humans and mice, which, in combination, can reduce the growth of antibiotic-resistant bacteria such as vancomycin-resistant Enterococcus faecium in vitro. Our studies suggest that lactulose and bifidobacteria serve as a synbiotic to reduce rates of infection in patients with severe liver disease.

Microbiota as the unifying factor behind the hallmarks of cancer

The human microbiota is a complex ecosystem that colonizes body surfaces and interacts with host organ systems, especially the immune system. Since the composition of this ecosystem depends on a variety of internal and external factors, each individual harbors a unique set of microbes. These differences in microbiota composition make individuals either more or less susceptible to various diseases, including cancer. Specific microbes are associated with cancer etiology and pathogenesis and several mechanisms of how they drive the typical hallmarks of cancer were recently identified. Although most microbes reside in the distal gut, they can influence cancer initiation and progression in distant tissues, as well as modulate the outcomes of established cancer therapies. Here, we describe the mechanisms by which microbes influence carcinogenesis and discuss their current and potential future applications in cancer diagnostics and management.

Sintilimab plus fluorouracil, leucovorin, oxaliplatin and docetaxel regimen as neoadjuvant therapy for resectable gastric cancer and biomarker exploration

At present, preoperative chemotherapy is the standard of care for the neoadjuvant treatment of potentially resectable gastric cancer (GC). However, because the efficacy and prognosis are not ideal, curative effects for this population are unsatisfactory. With the development of immune checkpoint inhibitors, the results of a few encouraging early trials of immunotherapeutic agents as neoadjuvant therapies for resectable GC have been reported. However, markers of the efficacy of immune checkpoint inhibitors remain unclear. This prospective single-center, single-arm observational study was designed to evaluate the efficacy of sintilimab plus the fluorouracil, leucovorin, oxaliplatin and docetaxel regimen as a neoadjuvant treatment for localized GC. More importantly, this work assesses multiple dimensions and include ctDNA, the immune microenvironment and intestinal microbiome to explore correlations between biomarkers and neoadjuvant therapeutic efficacy. Clinical trial registration: ChiCTR2200061629 (www.chictr.org.cn/index.aspx).

The interplay of obesity, microbiome dynamics, and innovative anti-obesity strategies in the context of endometrial cancer progression and therapeutic approaches

Endometrial cancer (EC) is the most common gynecologic malignancy in the United States, and its incidence and mortality are rising. Obesity is more tightly associated with EC than any other cancer. Thus, the rising prevalence of obesity and associated risk factors, including diabetes and insulin resistance, cause alarm. The metabolic derangements of obesity increase the bioavailability of estrogen, hyperinsulinemia, and inflammation in a complex system with direct and indirect effects on the endometrium, resulting in proliferation and, ultimately, carcinogenesis. In addition, the gut dysbiosis associated with obesity helps contribute to these metabolic derangements, priming an individual for developing EC and perhaps affecting treatment efficacy. More recent studies are beginning to explore obesity's effect on the local tumor microbiome of EC and its role in carcinogenesis. Significant and sustained weight loss in individuals can considerably decrease the risk of EC, likely through reversal of the altered metabolism and dysbiosis resulting obesity. Bariatric surgery is the gold standard for successful weight loss and highlights how reversing of the systemic effects of obesity can reduce EC risk. However, the current limited availability, knowledge, and imposed stigma of bariatric surgery prohibits population-level reductions in EC. Therefore, effective and maintainable non-surgical dietary and pharmacologic interventions are needed.

The triple interactions between gut microbiota, mycobiota and host immunity

The gut microbiome is mainly composed of microbiota and mycobiota, both of which play important roles in the development of the host immune system, metabolic regulation, and maintenance of intestinal homeostasis. With the increasing awareness of the pathogenic essence of infectious, immunodeficiency, and tumor-related diseases, the interactions between gut bacteria, fungi, and host immunity have been shown to directly influence the disease process or final therapeutic outcome, and collaborative and antagonistic relationships are commonly found between bacteria and fungi. Interventions represented by probiotics, prebiotics, engineered probiotics, fecal microbiota transplantation (FMT), and drugs can effectively modulate the triple interactions. In particular, traditional probiotics represented by Bifidobacterium and Lactobacillus and next-generation probiotics represented by Akkermansia muciniphila and Faecalibacterium prausnitzii showed a high enrichment trend in the gut of patients with a high response to inflammation remission and tumor immunotherapy, which predicts the potential medicinal value of these beneficial microbial formulations. However, there are bottlenecks in all these interventions that need to be broken. Meanwhile, further unraveling the underlying mechanisms of the "triple interactions" model can guide precise interventions and ultimately improve the efficiency of interventions on the host gut microbiome and immune modulation, thus directly or indirectly improving anti-inflammatory and tumor immunotherapy effects.

Modulating the gut microbiota by probiotics, prebiotics, postbiotics, and fecal microbiota transplantation: An emerging trend in cancer patient care

Treatment resistance, together with acute and late adverse effects, represents critical issues in the management of cancer patients. Promising results from preclinical and clinical research underline the emerging trend of a microbiome-based approach in oncology. Favorable bacterial species and higher gut diversity are associated with increased treatment efficacy, mainly in chemo- and immunotherapy. On the other hand, alterations in the composition and activity of gut microbial communities are linked to intestinal dysbiosis and contribute to high treatment-induced toxicity. In this Review, we provide an overview of studies concerning gut microbiota modulation in patients with solid and hematologic malignancies with a focus on probiotics, prebiotics, postbiotics, and fecal microbiota transplantation. Targeting the gut microbiome might bring clinical benefits and improve patient outcomes. However, a deeper understanding of mechanisms and large clinical trials concerning microbiome and immunological profiling is warranted to identify safe and effective ways to incorporate microbiota-based interventions in routine clinical practice.

Microbial influence on triggering and treatment of host cancer: An intestinal barrier perspective

Inflammatory bowel disease (IBD) is associated with complex complications that may lead to tumors. However, research on the mechanisms underlying susceptibility to chronic immune diseases and cancer pathogenesis triggered by the inflammatory environment remains limited. An imbalance in the host gut microbiota often accompanies intestinal inflammation. The delayed recovery of the dysregulated intestinal microbiota may exacerbate systemic inflammatory responses, multiorgan pathology, and metabolic disorders. This delay may also facilitate bacterial translocation. This review examined the relationship between gut barrier disruption and unbalanced microbial translocation and their impact on the brain, liver, and lungs. We also explored their potential roles in tumor initiation. Notably, the role of the intestinal microbiota in the development of inflammation is linked to the immune surveillance function of the small intestine and the repair status of the intestinal barrier. Moreover, adherence to a partially anti-inflammatory diet can aid in preventing the malignant transformation of inflammation by repairing the intestinal barrier and significantly reducing inflammation. In conclusion, enhancing intestinal barrier function may be a novel strategy for preventing and treating chronic malignancies in the intestine and other body areas.

The microbial metabolite desaminotyrosine enhances T-cell priming and cancer immunotherapy with immune checkpoint inhibitors

BACKGROUND

Inter-individual differences in response to immune checkpoint inhibitors (ICI) remain a major challenge in cancer treatment. The composition of the gut microbiome has been associated with differential ICI outcome, but the underlying molecular mechanisms remain unclear, and therapeutic modulation challenging.

METHODS

We established an in vivo model to treat C57Bl/6j mice with the type-I interferon (IFN-I)-modulating, bacterial-derived metabolite desaminotyrosine (DAT) to improve ICI therapy. Broad spectrum antibiotics were used to mimic gut microbial dysbiosis and associated ICI resistance. We utilized genetic mouse models to address the role of host IFN-I in DAT-modulated antitumour immunity. Changes in gut microbiota were assessed using 16S-rRNA sequencing analyses.

FINDINGS

We found that oral supplementation of mice with the microbial metabolite DAT delays tumour growth and promotes ICI immunotherapy with anti-CTLA-4 or anti-PD-1. DAT-enhanced antitumour immunity was associated with more activated T cells and natural killer cells in the tumour microenvironment and was dependent on host IFN-I signalling. Consistent with this, DAT potently enhanced expansion of antigen-specific T cells following vaccination with an IFN-I-inducing adjuvant. DAT supplementation in mice compensated for the negative effects of broad-spectrum antibiotic-induced dysbiosis on anti-CTLA-4-mediated antitumour immunity. Oral administration of DAT altered the gut microbial composition in mice with increased abundance of bacterial taxa that are associated with beneficial response to ICI immunotherapy.

INTERPRETATION

We introduce the therapeutic use of an IFN-I-modulating bacterial-derived metabolite to overcome resistance to ICI. This approach is a promising strategy particularly for patients with a history of broad-spectrum antibiotic use and associated loss of gut microbial diversity.

FUNDING

Melanoma Research Alliance, Deutsche Forschungsgemeinschaft, German Cancer Aid, Wilhelm Sander Foundation, Novartis Foundation.

The role of intermittent fasting and the ketogenic diet in cancer disease: can they replace the Mediterranean diet?

The prevalence of cancer is rising globally, and it is the second leading cause of death. Nutrition has an important influence on the risk of developing cancer. Moreover, changes in the gut microbiota are connected to the risk of developing cancer and are critical for sustaining immunity. Various studies have shown that intermittent fasting, ketogenic diet, and the Mediterranean diet are effective therapies in changing the intestinal microbiota, the prevention of cancer, and the improvement of tolerance to treatment in cancer patients. Although there is not enough evidence to show that the ketogenic diet is effective in changing the intestinal microbiota in a manner that could prevent cancer, intermittent fasting and the Mediterranean diet could positively affect composition of intestinal microbiota against cancer. In addition, the ketogenic diet, intermittent fasting, and the Mediterranean diet have the potential to stimulate anticarcinogenic pathways, and they might increase cancer patients' quality of life according to scientific evidence. In this review, we represent and argue recent scientific data on relationship between intermittent fasting, the ketogenic diet, and the Mediterranean diet, intestinal microbiota, cancer prevention and cancer treatment.

Neoadjuvant Durvalumab Alone or Combined with Novel Immuno-Oncology Agents in Resectable Lung Cancer: The Phase II NeoCOAST Platform Trial

Neoadjuvant chemoimmunotherapy improves pathologic complete response rate and event-free survival in patients with resectable non-small cell lung cancer (NSCLC) versus chemotherapy alone. NeoCOAST was the first randomized, multidrug platform trial to examine novel neoadjuvant immuno-oncology combinations for patients with resectable NSCLC, using major pathologic response (MPR) rate as the primary endpoint. Eighty-three patients received a single cycle of treatment: 26 received durvalumab (anti-PD-L1) monotherapy, 21 received durvalumab plus oleclumab (anti-CD73), 20 received durvalumab plus monalizumab (anti-NKG2A), and 16 received durvalumab plus danvatirsen (anti-STAT3 antisense oligonucleotide). MPR rates were higher for patients in the combination arms versus durvalumab alone. Safety profiles for the combinations were similar to those of durvalumab alone. Multiplatform immune profiling suggested that improved MPR rates in the durvalumab plus oleclumab and durvalumab plus monalizumab arms were associated with enhanced effector immune infiltration of tumors, interferon responses and markers of tertiary lymphoid structure formation, and systemic functional immune cell activation.

SIGNIFICANCE

A neoadjuvant platform trial can rapidly generate clinical and translational data using candidate surrogate endpoints like MPR. In NeoCOAST, patients with resectable NSCLC had improved MPR rates after durvalumab plus oleclumab or monalizumab versus durvalumab alone and tumoral transcriptomic signatures indicative of augmented immune cell activation and function. See related commentary by Cooper and Yu, p. 2306. This article is featured in Selected Articles from This Issue, p. 2293.

Role of the intratumoral microbiome in tumor progression and therapeutics implications

Microbes are widely present in various organs of the human body and play important roles in numerous physiological and pathological processes. Nevertheless, owing to multiple limiting factors, such as contamination and low biomass, the current understanding of the intratumoral microbiome is limited. The intratumoral microbiome exerts tumor-promoting or tumor-suppressive effects by engaging in metabolic reactions within the body, regulating signaling cancer-related pathways, and impacting both host cells function and immune system. It is important to emphasize that intratumoral microbes exhibit substantial heterogeneity in terms of composition and abundance across various tumor types, thereby potentially influencing diverse aspects of tumorigenesis, progression, and metastasis. These findings suggest that intratumoral microbiome have great potential as diagnostic and prognostic biomarkers. By manipulating the intratumoral microbes to employ cancer therapy, the efficacy of chemotherapy or immunotherapy can be enhanced while minimizing adverse effects. In this review, we comprehensively describe the composition and function of the intratumoral microbiome in various human solid tumors. Combining recent advancements in research, we discuss the origins, mechanisms, and prospects of the clinical applications of intratumoral microbiome.

Manipulating the gut and tumor microbiota for immune checkpoint inhibitor therapy: from dream to reality

The past decade has witnessed a revolution in cancer treatment by shifting from conventional therapies to immune checkpoint inhibitors (ICIs). These immunotherapies unleash the host immune system against the tumor and have achieved unprecedented durable remission. However, 80% of patients do not respond. This review discusses how bacteria are unexpected drivers that reprogram tumor immunity. Manipulating the microbiota impacts on tumor development and reprograms the tumor microenvironment (TME) of mice on immunotherapy. We anticipate that harnessing commensals and the tumor microbiome holds promise to identify patients who will benefit from immunotherapy and guide the choice of new ICI combinations to advance treatment efficacy.

Supplementation with a high-glucose drink stimulates anti-tumor immune responses to glioblastoma via gut microbiota modulation

A high-sugar diet induces lifestyle-associated metabolic diseases, such as obesity and diabetes, which may underlie the pro-tumor effects of a high-sugar diet. We supply GL261 syngeneic glioblastoma (GBM) mice with a short-term high-glucose drink (HGD) and find an increased survival rate with no evidence of metabolic disease. Modulation of the gut microbiota through HGD supplementation is critical for enhancing the anti-tumor immune response. Single-cell RNA sequencing shows that gut microbiota modulation by HGD supplementation increases the T cell-mediated anti-tumor immune response in GBM mice. We find that the cytotoxic CD4+ T cell population in GBM is increased due to synergy with anti-programmed cell death protein 1 (anti-PD-1) immune checkpoint inhibitors, but this effect depends upon HGD supplementation. Thus, we determine that HGD supplementation enhances anti-tumor immune responses in GBM mice through gut microbiota modulation and suggest that the role of HGD supplementation in GBM should be re-examined.

Tumor microbiome analysis provides prognostic value for patients with stage III colorectal cancer

Introduction

Although patients with colorectal cancer (CRC) can receive optimal treatment, the risk of recurrence remains. This study aimed to evaluate whether the tumor microbiome can be a predictor of recurrence in patients with stage III CRC.

Methods

Using 16S rRNA gene sequencing, we analyzed the microbiomes of tumor and adjacent tissues acquired during surgery in 65 patients with stage III CRC and evaluated the correlation of the tissue microbiome with CRC recurrence. Additionally, the tumor tissue microbiome data of 71 patients with stage III CRC from another center were used as a validation set.

Results

The microbial diversity and abundance significantly differed between tumor and adjacent tissues. In particular, Streptococcus and Gemella were more abundant in tumor tissue samples than in adjacent tissue samples. The microbial diversity and abundance in tumor and adjacent tissues did not differ according to the presence of recurrence, except for one genus in the validation set. Logistic regression analysis revealed that a recurrence prediction model including tumor tissue microbiome data had a better prediction performance than clinical factors (area under the curve [AUC] 0.846 vs. 0.679, p = 0.009), regardless of sex (male patients: AUC 0.943 vs. 0.818, p = 0.043; female patients: AUC 0.885 vs. 0.590, p = 0.017). When this prediction model was applied to the validation set, it had a higher AUC value than clinical factors in female patients.

Conclusion

Our results suggest that the tumor microbiome of patients with CRC be a potential predictor of postoperative disease recurrence.

The Gut Microbiome from a Biomarker to a Novel Therapeutic Strategy for Immunotherapy Response in Patients with Lung Cancer

The gastrointestinal microbiome has been shown to play a key role in determining the responses to cancer immunotherapy, including immune checkpoint inhibitor (ICI) therapy and CAR-T. In patients with non-small cell lung cancer (NSCLC), increasing evidence suggests that a microbiome composition signature is associated with clinical response to ICIs as well as with the development of immune-related adverse events. In support of this, antibiotic (ATB)-related dysbiosis has been consistently linked with the deleterious impact of ICI response, shortening the overall survival (OS) among patients on ATBs prior to ICI initiation. In parallel, several preclinical experiments have unravelled various strategies using probiotics, prebiotics, diet, and fecal microbiota transplantation as new therapeutic tools to beneficially shift the microbiome and enhance ICI efficacy. These approaches are currently being evaluated in clinical trials and have achieved encouraging preliminary results. In this article, we reviewed the recent studies on the gut microbiome as a potential biomarker and an adjuvant therapy to ICIs in NSCLC patients.

Computed Tomography-Based Quantitative Texture Analysis and Gut Microbial Community Signatures Predict Survival in Non-Small Cell Lung Cancer

This study aims to combine computed tomography (CT)-based texture analysis (QTA) and a microbiome-based biomarker signature to predict the overall survival (OS) of immune checkpoint inhibitor (ICI)-treated non-small cell lung cancer (NSCLC) patients by analyzing their CT scans (n = 129) and fecal microbiome (n = 58). One hundred and five continuous CT parameters were obtained, where principal component analysis (PCA) identified seven major components that explained 80% of the data variation. Shotgun metagenomics (MG) and ITS analysis were performed to reveal the abundance of bacterial and fungal species. The relative abundance of Bacteroides dorei and Parabacteroides distasonis was associated with long OS (>6 mo), whereas the bacteria Clostridium perfringens and Enterococcus faecium and the fungal taxa Cortinarius davemallochii, Helotiales, Chaetosphaeriales, and Tremellomycetes were associated with short OS (≤6 mo). Hymenoscyphus immutabilis and Clavulinopsis fusiformis were more abundant in patients with high (≥50%) PD-L1-expressing tumors, whereas Thelephoraceae and Lachnospiraceae bacterium were enriched in patients with ICI-related toxicities. An artificial intelligence (AI) approach based on extreme gradient boosting evaluated the associations between the outcomes and various clinicopathological parameters. AI identified MG signatures for patients with a favorable ICI response and high PD-L1 expression, with 84% and 79% accuracy, respectively. The combination of QTA parameters and MG had a positive predictive value of 90% for both therapeutic response and OS. According to our hypothesis, the QTA parameters and gut microbiome signatures can predict OS, the response to therapy, the PD-L1 expression, and toxicity in NSCLC patients treated with ICI, and a machine learning approach can combine these variables to create a reliable predictive model, as we suggest in this research.

Bifidobacterium affects antitumor efficacy of oncolytic adenovirus in a mouse model of melanoma

Gut microbiota plays a key role in modulating responses to cancer immunotherapy in melanoma patients. Oncolytic viruses (OVs) represent emerging tools in cancer therapy, inducing a potent immunogenic cancer cell death (ICD) and recruiting immune cells in tumors, poorly infiltrated by T cells. We investigated whether the antitumoral activity of oncolytic adenovirus Ad5D24-CpG (Ad-CpG) was gut microbiota-mediated in a syngeneic mouse model of melanoma and observed that ICD was weakened by vancomycin-mediated perturbation of gut microbiota. Ad-CpG efficacy was increased by oral supplementation with Bifidobacterium, reducing melanoma progression and tumor-infiltrating regulatory T cells. Fecal microbiota was enriched in bacterial species belonging to the Firmicutes phylum in mice treated with both Bifidobacterium and Ad-CpG; furthermore, our data suggest that molecular mimicry between melanoma and Bifidobacterium-derived epitopes may favor activation of cross-reactive T cells and constitutes one of the mechanisms by which gut microbiota modulates OVs response.

The impact of the gut microbiome on tumor immunotherapy: from mechanism to application strategies

Immunotherapy is one of the fastest developing areas in the field of oncology. Many immunological treatment strategies for refractory tumors have been approved and marketed. Nevertheless, much clinical and preclinical experimental evidence has shown that the efficacy of immunotherapy in tumor treatment varies markedly among individuals. The commensal microbiome mainly colonizes the intestinal lumen in humans, is affected by a variety of factors and exhibits individual variation. Moreover, the gut is considered the largest immune organ of the body due to its influence on the immune system. In the last few decades, with the development of next-generation sequencing (NGS) techniques and in-depth research, the view that the gut microbiota intervenes in antitumor immunotherapy through the immune system has been gradually confirmed. Here, we review important studies published in recent years focusing on the influences of microbiota on immune system and the progression of malignancy. Furthermore, we discuss the mechanism by which microbiota affect tumor immunotherapy, including immune checkpoint blockade (ICB) and adoptive T-cell therapy (ACT), and strategies for modulating the microbial composition to facilitate the antitumor immune response. Finally, opportunity and some challenges are mentioned to enable a more systematic understanding of tumor treatment in the future and promote basic research and clinical application in related fields.