The gut microbiota influences anticancer immunosurveillance and general health

Neoadjuvant Immunotherapy: Leveraging the Immune System to Treat Early-Stage Disease

Given the success of immunotherapy in treating patients with metastatic disease in a variety of tumor types, there is tremendous enthusiasm for expanding the use of immunotherapy to those with early-stage cancer. Administering immunotherapy in the neoadjuvant, preoperative setting is a biologically sound approach because preclinical studies have shown that stronger and broader immune responses can be generated if immunotherapy is administered while the tumor and/or draining lymph nodes are intact. It is therefore likely that administering immunotherapy preoperatively will generate optimal immune responses, leading to high rates of pathologic response as well as improved long-term survival. Although neoadjuvant immunotherapy is currently only approved for use in combination with chemotherapy in triple-negative breast cancer and non-small cell lung cancer, it is anticipated that ongoing and future clinical trials will further define the role of neoadjuvant immunotherapy in many cancer types. These trials should be designed with appropriate survival endpoints and rigorous correlative studies to include imaging and biospecimen-based analyses to address currently unanswered questions that must be resolved to optimize the use of immunotherapy in early-stage disease.

A Natural Polyphenol Exerts Antitumor Activity and Circumvents Anti-PD-1 Resistance through Effects on the Gut Microbiota

Several approaches to manipulate the gut microbiome for improving the activity of cancer immune-checkpoint inhibitors (ICI) are currently under evaluation. Here, we show that oral supplementation with the polyphenol-rich berry camu-camu (CC; Myrciaria dubia) in mice shifted gut microbial composition, which translated into antitumor activity and a stronger anti-PD-1 response. We identified castalagin, an ellagitannin, as the active compound in CC. Oral administration of castalagin enriched for bacteria associated with efficient immunotherapeutic responses (Ruminococcaceae and Alistipes) and improved the CD8+/FOXP3+CD4+ ratio within the tumor microenvironment. Moreover, castalagin induced metabolic changes, resulting in an increase in taurine-conjugated bile acids. Oral supplementation of castalagin following fecal microbiota transplantation from ICI-refractory patients into mice supported anti-PD-1 activity. Finally, we found that castalagin binds to Ruminococcus bromii and promoted an anticancer response. Altogether, our results identify castalagin as a polyphenol that acts as a prebiotic to circumvent anti-PD-1 resistance.

SIGNIFICANCE

The polyphenol castalagin isolated from a berry has an antitumor effect through direct interactions with commensal bacteria, thus reprogramming the tumor microenvironment. In addition, in preclinical ICI-resistant models, castalagin reestablishes the efficacy of anti-PD-1. Together, these results provide a strong biological rationale to test castalagin as part of a clinical trial. This article is highlighted in the In This Issue feature, p. 873.

Gut Microbiome Alterations Affect Glioma Development and Foxp3 Expression in Tumor Microenvironment in Mice

Glioma is the most common malignant tumor of the central nervous system (CNS), with high degree of malignancy and poor prognosis. The gut microbiome (GM) is composed of microorganisms with different properties and functions, which play an important role in human physiology and biological activities. It has been proved that GM can affect the development of glioma through natural immunity, but whether GM can affect glioma through adaptive immunity and whether there are some microorganisms in the GM that may affect glioma growth still remain unclear. In our study, we evaluated the relationship between GM and glioma. We proved that (I) glioma growth can induce structural changes of mouse GM, including the decreased abundance of Bacteroidia and increased abundance of Firmicutes. (II) GM dysbiosis can downregulate Foxp3 expression in the brain and promote glioma growth. A balanced environment of GM can upregulate the expression of Foxp3 in the brain and delay the development of glioma. (III) The increased abundance of Bacteroidia is associated with accelerated glioma progression, while its decreased abundance is associated with delayed glioma progression, which may be one of the key microorganisms affecting glioma growth. This study is helpful to reveal the relationship between GM and glioma development and provide new ideas for adjuvant therapy of glioma.

Prognostic Value of Fusobacterium nucleatum after Abdominoperineal Resection for Anal Squamous Cell Carcinoma

Main prognostic factors of anal squamous cell carcinoma (ASCC) are tumor size, differentiation, lymph node involvement, and male gender. However, they are insufficient to predict relapses after exclusive radiotherapy (RT) or chemoradiotherapy (CRT). Fusobacterium nucleatum has been associated with poor prognosis in several digestive cancers. In this study, we assessed the association between intratumoral F. nucleatum load and clinico-pathological features, relapse, and survival in patients with ASCC who underwent abdominoperineal resection (APR) after RT/CRT. We retrospectively analyzed surgical samples from a cohort of 166 patients with ASCC who underwent APR. F. nucleatum 16S rRNA gene sequences were quantified using real-time quantitative PCR. We associated F. nucleatum load with classical clinicopathological features, overall survival (OS), disease-free survival (DFS), and metastasis-free survival (MFS) using Cox regression univariate and multivariate analyses. Tumors harboring high loads of F. nucleatum (highest tercile) showed longer OS and DFS (median: not reached vs. 50.1 months, p = 0.01, and median: not reached vs. 18.3 months, p = 0.007, respectively). High F. nucleatum load was a predictor of longer OS (HR = 0.55, p = 0.04) and DFS (HR = 0.50, p = 0.02) in multivariate analysis. High F. nucleatum load is an independent favorable prognostic factor in patients with ASCC who underwent APR.

Immune system and intestinal microbiota determine efficacy of androgen deprivation therapy against prostate cancer

Background

Prostate cancer (PC) responds to androgen deprivation therapy (ADT) usually in a transient fashion, progressing from hormone-sensitive PC (HSPC) to castration-resistant PC (CRPC). We investigated a mouse model of PC as well as specimens from PC patients to unravel an unsuspected contribution of thymus-derived T lymphocytes and the intestinal microbiota in the efficacy of ADT.

Methods

Preclinical experiments were performed in PC-bearing mice, immunocompetent or immunodeficient. In parallel, we prospectively included 65 HSPC and CRPC patients (Oncobiotic trial) to analyze their feces and blood specimens.

Results

In PC-bearing mice, ADT increased thymic cellularity and output. PC implanted in T lymphocyte-depleted or athymic mice responded less efficiently to ADT than in immunocompetent mice. Moreover, depletion of the intestinal microbiota by oral antibiotics reduced the efficacy of ADT. PC reduced the relative abundance of Akkermansia muciniphila in the gut, and this effect was reversed by ADT. Moreover, cohousing of PC-bearing mice with tumor-free mice or oral gavage with Akkermansia improved the efficacy of ADT. This appears to be applicable to PC patients because long-term ADT resulted in an increase of thymic output, as demonstrated by an increase in circulating recent thymic emigrant cells (sjTRECs). Moreover, as compared with HSPC controls, CRPC patients demonstrated a shift in their intestinal microbiota that significantly correlated with sjTRECs. While feces from healthy volunteers restored ADT efficacy, feces from PC patients failed to do so.

Conclusions

These findings suggest the potential clinical utility of reversing intestinal dysbiosis and repairing acquired immune defects in PC patients.

Gut Microbiota: A Promising Milestone in Enhancing the Efficacy of PD1/PD-L1 Blockade Therapy

In the past few decades, immunotherapy has emerged as one of the most promising strategies among current treatments of cancer. In particular, the field of PD1/PD-L1 inhibitors has been boosted, widely applied into clinical practice with potent therapeutic efficacy and remarkable survival benefits on various cancers such as melanoma, non-small cell lung cancer (NSCLC), and urothelial carcinoma (UC). However, the application of PD1/PD-L1 blockade therapy is still quite restricted because of unexpected toxicities, limited response rate, as well as associated resistance. In consequence, searching for potential strategies that possibly resolve the existing limitations and enhance the therapeutic responsiveness of PD1/PD-L1 blockade is of great significance. Fortunately, the gut microbiome has been demonstrated to serve as a pivotal regulator in anti-PD1/PD-L1 therapy, providing an applicable tool to improve anti-PD1/PD-L1 clinical efficacy. In this review, we summarized published advancements about how microbiota modulated in anti-PD1/PD-L1 therapy and illustrated its underlying mechanisms, giving insights into putative manipulation of gut microbiota to facilitate PD1/PD-L1 blockade.

Cell-intrinsic view of the aryl hydrocarbon receptor in tumor immunity

Emerging insights into aryl hydrocarbon receptor (Ahr) biology have revealed its key role in regulating mammalian host immunity and tissue homeostasis. Depending on the context, immune cells can play either a pro- or antitumor role in cancer. Ahr has classically been viewed as protumorigenic; however, given recent advances in our understanding of Ahr functions, especially in the immune system, this view requires reassessment. Moreover, given its cell type-specific activity, therapeutic exploitation of the Ahr pathway should be cautiously considered. We describe the function of Ahr in different immune cells, and connect with their roles in cancer immunology. In addition, we discuss clinical perspectives of how recent advances in our understanding of Ahr biology might be therapeutically applied to improve cancer outcomes.

The Different Immune Profiles of Normal Colonic Mucosa in Cancer-Free Lynch Syndrome Carriers and Lynch Syndrome Colorectal Cancer Patients

BACKGROUND & AIMS

Owing to the high load of immunogenic frameshift neoantigens, tumors arising in individuals with Lynch syndrome (LS), the most common inherited colorectal cancer (CRC) syndrome, are characterized by a pronounced immune infiltration. However, the immune status of normal colorectal mucosa in LS is not well characterized. We assessed the immune infiltrate in tumor-distant normal colorectal mucosa from LS CRC patients, sporadic microsatellite-unstable (MSI) and microsatellite-stable (MSS) CRC patients, and cancer-free LS carriers.

METHODS

CD3-positive, FOXP3-positive, and CD8-positive T cells were quantified in, respectively, 219, 233, and 201 formalin-fixed paraffin-embedded (FFPE) normal colonic mucosa tissue sections from CRC patients and cancer-free LS carriers and 26, 22, and 19 LS CRCs. CD3-positive T cells were also quantified in an independent cohort of 97 FFPE normal rectal mucosa tissue sections from LS carriers enrolled in the CAPP2 clinical trial. The expression of 770 immune-relevant genes was analyzed in a subset of samples with the use of the NanoString nCounter platform.

RESULTS

LS normal mucosa specimens showed significantly elevated CD3-, FOXP3-, and CD8-positive T-cell densities compared with non-LS control specimens. Gene expression profiling and cluster analysis revealed distinct immune profiles in LS carrier mucosa with and without cancer manifestation. Long-term follow-up of LS carriers within the CAPP2 trial found a correlation between mucosal T-cell infiltrate and time to subsequent tumor occurrence.

CONCLUSIONS

LS carriers show elevated mucosal T-cell infiltration even in the absence of cancer. The normal mucosa immune profile may be a temporary or permanent tumor risk modifier in LS carriers.

Crosstalk between the gut microbiome and clinical response in locally advanced thoracic esophageal squamous cell carcinoma during neoadjuvant camrelizumab and chemotherapy

Background

The gut microbiome is associated with the response to immunotherapy in a variety of advanced cancers. However, the influence of the gut microbiome on locally advanced esophageal squamous cell carcinoma (ESCC) during programmed cell death protein 1 (PD-1) antibody immunotherapy plus chemotherapy is not clearly demonstrated. To explore the crosstalk between the gut microbiome and clinical response in locally advanced thoracic ESCC during neoadjuvant camrelizumab and chemotherapy

Methods

Patients who were diagnosed with locally advanced thoracic ESCC and had not received treatment were enrolled. The treatment regimen was two cycles of camrelizumab combined with carboplatin and albumin paclitaxel before surgery. The research endpoints were pathological complete response (pCR) and major pathological response (MPR). Fecal samples were collected at three time points: before neoadjuvant therapy, after two cycles of neoadjuvant therapy, and after surgery. We performed 16S ribosomal ribonucleic acid (rRNA) V3–V4 sequencing of the gene amplicons of fecal samples, as well as bacterial diversity and differential abundance analyses.

Results

A total of 46 patients were recruited, and 44, 42, and 35 fecal samples were collected at the three time points, respectively. Statistically significant differences were observed in the amplicon sequence variant (ASV)-level alpha diversity indices, including Chao1, Shannon, and Good’s coverage, between the three time points. The non-pCR-enriched gut microbiota included Proteobacteria, Dialister, Aeromonadales, Pseudomonadales, Thermi, Deinococci, Moraxellaceae, Rhodocyclales, Rhodocyclaceae, and Acinetobacter. The non-MPR-enriched gut microbiota included Pseudomonadales and the mitochondria family. The MPR-enriched gut microbiota included the Barnesiellaceae, Pyramidobacter, Dethiosulfovibrionaceae, Odoribacteraceae, Butyricimonas, Prevotella, Barnesiella, and Odoribacter. Patients with ≥3 grade adverse events (AEs) exhibited enrichment in the Succiniclasticum, Nakamurella, Rhizobium, Granulicella, Phyllobacteriaceae, Pelagibacteraceae, Actinosynnemataceae, Aquirestis, Flavisolibacter, Chelativorans, Coxiellaceae Acidicapsa, Acidobacteriaceae, Lentzea, Staphylococcus, Plesiomonas, Dysgonomonas, Pseudonocardia, and Ellin6075.

Conclusions

We found that the diversity of the gut microbiome declined after neoadjuvant PD-1 antibody immunotherapy plus chemotherapy and surgery. Patients with pCR had different types and proportions of gut microbiota before treatment compared to those without pCR. We also observed the difference between patients with or without ≥ grade 3 AEs. The taxonomic features of the gut microbiome are potential biomarkers that could predict the pathological response and AEs.

The gut microbiota can orchestrate the signaling pathways in colorectal cancer

Current evidence suggests that bacteria contribute to the development of certain cancers, such as colorectal cancer (CRC), partly by stimulating chronic inflammation. However, little is known about the bacterial impact on molecular pathways in CRC. Recent studies have demonstrated how specific bacteria can influence the major CRC-related pathways, i.e., Wnt, PI3K-Akt, MAPK, TGF-β, EGFR, mTOR, and p53. In order to advance the current understanding and facilitate the choice of pathways to investigate, we have systematically collected and summarized the current knowledge within bacterial altered major pathways in CRC. Several pro-tumorigenic and anti-tumorigenic bacterial species and their respective metabolites interfere with the major signaling pathways addressed in this review. Not surprisingly, some of these studies investigated known CRC drivers, such as Escherichia coli, Fusobacterium nucleatum, and Bacteroides fragilis. Interestingly, some metabolites produced by bacterial species typically considered pathogenic, e.g., Vibrio cholera, displayed anti-tumorigenic activities, emphasizing the caution needed when classifying healthy and unhealthy microorganisms. The results collectively emphasize the complexity of the relationship between the microbiota and the tumorigenesis of CRC, and future studies should verify these findings in more realistic models, such as organoids, which constitute a promising platform. Moreover, future trials should investigate the clinical potential of preventive modulation of the gut microbiota regarding CRC development.

Characterization of Alistipes montrealensis sp. nov., Isolated from Human Feces of a Patient with Metastatic Melanoma Treated with Immune Checkpoint Inhibitors

Fecal microbiome culturomics of a cancer patient treated with immune checkpoint inhibitors led to the identification of a Gram-negative, rod-shaped, obligate anaerobic, non-motile, non-spore-forming bacterium, designated strain kh20T, which was phylogenetically assigned to the genus Alistipes. Strain kh20T demonstrated a 98.61% 16S rRNA sequence similarity with A.shahii WAL 8301T. The bacteria cells generated catalase but no oxidase. Iso-C15:0 (26.6%), anteiso-C15:0 (19.9%), and iso-C17:0 (17.2%) were the major cellular fatty acids identified in its composition. The G+C content of its genome was 57.2%. Strain kh20T showed significantly low values for DNA-DNA Hybridation (DDH ≤ 33.70%) and Average Nucleotide Identity (ANI ≤ 86.35%) compared with other Alistipes species. Based on these findings, we concluded that strain kh20T represented a novel bacterium, and we proposed the name Alistipes montrealensis sp. nov. (CECT 30384 and CSUR Q6005).

Gut microbiota-drug interactions in cancer pharmacotherapies: implications for efficacy and adverse effects

INTRODUCTION

The gut microbiota is involved in host physiology and health. Reciprocal microbiota-drug interactions are increasingly recognized as underlying some individual differences in therapy response and adverse events. Cancer pharmacotherapies are characterized by a high degree of interpatient variability in efficacy and side effect profile and recently, the microbiota has emerged as a factor that may underlie these differences.

AREAS COVERED

The effects of cancer pharmacotherapy on microbiota composition and function are reviewed with consideration of the relationship between baseline microbiota composition, microbiota modification, antibiotics exposure and cancer therapy efficacy. We assess the evidence implicating the microbiota in cancer therapy-related adverse events including impaired gut function, cognition and pain perception. Finally, potential mechanisms underlying microbiota-cancer drug interactions are described, including direct microbial metabolism, and microbial modulation of liver metabolism and immune function. This review focused on preclinical and clinical studies conducted in the last 5 years.

EXPERT OPINION

Preclinical and clinical research supports a role for baseline microbiota in cancer therapy efficacy, with emerging evidence that the microbiota modification may assist in side effect management. Future efforts should focus on exploiting this knowledge towards the development of microbiota-targeted therapies. Finally, a focus on specific drug-microbiota-cancer interactions is warranted.

Intestinal Microbiome Associated With Immune-Related Adverse Events for Patients Treated With Anti-PD-1 Inhibitors, a Real-World Study

Aim

Immune checkpoint inhibitors (ICIs) have updated the treatment landscape for patients with advanced malignancies, while their clinical prospect was hindered by severe immune-related adverse events (irAEs). The aim of this study was to research the association between gut microbiome diversity and the occurrence of ICI-induced irAEs.

Patients and Method

We prospectively obtained the baseline fecal samples and clinical data from patients treated with anti-PD-1 inhibitors as monotherapy or in combination with chemotherapy or antiangiogenesis regardless of treatment lines. The 16S rRNA V3-V4 sequencing was used to test the gene amplicons of fecal samples. The development of irAEs was evaluated and monitored from the beginning of therapy based on CTCAE V5.01.

Results

A total of 150 patients were included in the study and followed up for at least 6 months. A total of 90 (60%) patients developed at least one type of adverse effect, among which mild irAEs (grades 1–2) occurred in 65 patients (72.22%) and severe irAEs (grades 3–5) in 25 patients (27.78%). Patients with severe irAEs showed a visible higher abundance of Streptococcus, Paecalibacterium, and Stenotrophomonas, and patients with mild irAEs had a higher abundance of Faecalibacterium and unidentified_Lachnospiraceae. With the aid of a classification model constructed with 5 microbial biomarkers, patients without irAEs were successfully distinguished from those with severe irAEs (AUC value was 0.66).

Conclusion

Certain intestinal bacteria can effectively distinguish patients without irAEs from patients with severe irAEs and provide evidence of gut microbiota as an informative source for developing predictive biomarkers to predict the occurrence of irAEs.

Species-targeted sorting and cultivation of commensal bacteria from the gut microbiome using flow cytometry under anaerobic conditions

BACKGROUND

There is a growing interest in using gut commensal bacteria as "next generation" probiotics. However, this approach is still hampered by the fact that there are few or no strains available for specific species that are difficult to cultivate. Our objective was to adapt flow cytometry and cell sorting to be able to detect, separate, isolate, and cultivate new strains of commensal species from fecal material. We focused on the extremely oxygen sensitive (EOS) species Faecalibacterium prausnitzii and the under-represented, health-associated keystone species Christensenella minuta as proof-of-concept.

RESULTS

A BD Influx® cell sorter was equipped with a glovebox that covered the sorting area. This box was flushed with nitrogen to deplete oxygen in the enclosure. Anaerobic conditions were maintained during the whole process, resulting in only minor viability loss during sorting and culture of unstained F. prausnitzii strains ATCC 27766, ATCC 27768, and DSM 17677. We then generated polyclonal antibodies against target species by immunizing rabbits with heat-inactivated bacteria. Two polyclonal antibodies were directed against F. prausnitzii type strains that belong to different phylogroups, whereas one was directed against C. minuta strain DSM 22607. The specificity of the antibodies was demonstrated by sorting and sequencing the stained bacterial fractions from fecal material. In addition, staining solutions including LIVE/DEAD™ BacLight™ Bacterial Viability staining and polyclonal antibodies did not severely impact bacterial viability while allowing discrimination between groups of strains. Finally, we combined these staining strategies as well as additional criteria based on bacterial shape for C. minuta and were able to detect, isolate, and cultivate new F. prausnitzii and C. minuta strains from healthy volunteer's fecal samples.

CONCLUSIONS

Targeted cell-sorting under anaerobic conditions is a promising tool for the study of fecal microbiota. It gives the opportunity to quickly analyze microbial populations, and can be used to sort EOS and/or under-represented strains of interest using specific antibodies, thus opening new avenues for culture experiments. Video abstract.

Intestinal Akkermansia muciniphila predicts clinical response to PD-1 blockade in patients with advanced non-small-cell lung cancer

Aside from PD-L1 expression, biomarkers of response to immune checkpoint inhibitors (ICIs) in non-small-cell lung cancer (NSCLC) are needed. In a previous retrospective analysis, we documented that fecal Akkermansia muciniphila (Akk) was associated with clinical benefit of ICI in patients with NSCLC or kidney cancer. In the current study, we performed shotgun-metagenomics-based microbiome profiling in a large cohort of patients with advanced NSCLC (n = 338) treated with first- or second-line ICIs to prospectively validate the predictive value of fecal Akk. Baseline stool Akk was associated with increased objective response rates and overall survival in multivariate analyses, independent of PD-L1 expression, antibiotics, and performance status. Intestinal Akk was accompanied by a richer commensalism, including Eubacterium hallii and Bifidobacterium adolescentis, and a more inflamed tumor microenvironment in a subset of patients. However, antibiotic use (20% of cases) coincided with a relative dominance of Akk above 4.8% accompanied with the genus Clostridium, both associated with resistance to ICI. Our study shows significant differences in relative abundance of Akk that may represent potential biomarkers to refine patient stratification in future studies.

Redrawing therapeutic boundaries: microbiota and cancer

The unexpected roles of the microbiota in cancer challenge explanations of carcinogenesis that focus on tumor-intrinsic properties. Most tumors contain bacteria and viruses, and the host's proximal and distal microbiota influence both cancer incidence and therapeutic responsiveness. Continuing the history of cancer-microbe research, these findings raise a key question: to what extent is the microbiota relevant for clinical oncology? We approach this by critically evaluating three issues: how the microbiota provides a predictive biomarker of cancer growth and therapeutic responsiveness, the microbiota's causal role(s) in cancer development, and how therapeutic manipulations of the microbiota improve patient outcomes in cancer. Clarifying the conceptual and empirical aspects of the cancer-associated microbiota can orient future research and guide its implementation in clinical oncology.

Immunostimulatory effects of vitamin B5 improve anticancer immunotherapy

Vitamin B5 (panthotenic acid), the precursor of coenzyme A (CoA), is contained in most food items and is produced by the intestinal microbiota. A recent study published in Cell Metabolism reports that vitamin B5 and CoA favor the differentiation of CD8⁺ cytotoxic T cells into interleukin-22 (IL-22)-producing Tc22 cells, likely through fueling mitochondrial metabolism. Importantly, in a small cohort of melanoma patients, the plasma levels of vitamin B5 positively correlate with responses to PD-1-targeted immunotherapy. Moreover, in mice, supplementation with vitamin B5 increases the efficacy of PD-L1-targeted cancer immunotherapy, and in vitro culture of T cells with CoA enhances their antitumor activity upon adoptive transfer into mice. These finding suggest that vitamin B5 is yet another B vitamin that stimulates anti-cancer immunosurveillance.

Native and Engineered Probiotics: Promising Agents against Related Systemic and Intestinal Diseases

Intestinal homeostasis is a dynamic balance involving the interaction between the host intestinal mucosa, immune barrier, intestinal microecology, nutrients, and metabolites. Once homeostasis is out of balance, it will increase the risk of intestinal diseases and is also closely associated with some systemic diseases. Probiotics (Escherichia coli Nissle 1917, Akkermansia muciniphila, Clostridium butyricum, lactic acid bacteria and Bifidobacterium spp.), maintaining the gut homeostasis through direct interaction with the intestine, can also exist as a specific agent to prevent, alleviate, or cure intestinal-related diseases. With genetic engineering technology advancing, probiotics can also show targeted therapeutic properties. The aims of this review are to summarize the roles of potential native and engineered probiotics in oncology, inflammatory bowel disease, and obesity, discussing the therapeutic applications of these probiotics.

The diversity of the intestinal microbiota in patients with alcohol use disorder and its relationship to alcohol consumption and cognition

INTRODUCTION

Alcohol use disorder (AUD) has evolved into a severe social and medical issue. However, the exact environmental factors triggering AUD pathophysiology remain unknown. A growing body of research has shown that environmental elements can affect the brain via the microbiota-gut-brain axis.

METHODS

We employed 16S rRNA gene sequencing technology to investigate the composition and diversity of intestinal microbiota in 32 AUD males and 35 healthy controls (HCs), as well as its relationship on cognitive function.

RESULTS

Our findings showed that the alpha diversity indices in AUDs were much lower than HCs. The abundances of Faecalibacterium, Gemmiger, Lachnospiracea_incertae_sedis, Megamonas, and Escherichia were significantly different between AUD and HC groups and could be used as a basis for judging whether excessive drinking. The abundances of Faecalibacterium, Gemmiger, Escherichia, and Fusobacterium can be used to judge the cognitive function of the population.

CONCLUSION

These data suggested that the gut dysbiosis in AUD patients, and some specific microbiota were considered to be related to alcohol intake and cognitive function. This study provides important information for further study of the pathogenesis of AUD from the perspective of intestinal microbiota.

Characteristics of Gut Microbiome and Its Metabolites, Short-Chain Fatty Acids, in Children With Idiopathic Short Stature

BACKGROUND

The gut microbiome is important for host nutrition and metabolism. Whether the gut microbiome under normal diet regulate human height remains to be addressed. Our study explored the possible relationship between gut microbiota, its metabolic products and the pathogenesis of idiopathic short stature disease (ISS) by comparing the gut microbiota between children with ISS and of normal height, and also the short-chain fatty acids (SCFAs) produced by the gut microbiota.

METHODS

The subjects of this study were 32 prepubescent children aged 4-8 years. The fecal microbial structure of the subjects was analyzed by 16S rRNA high-throughput sequencing technology. The concentrations of SCFAs in feces were determined by gas chromatography-mass spectrometry.

RESULTS

The richness of gut microbiota in ISS group was decreased, and the composition of gut microbiota was significantly different between ISS group and control group. The relative abundance of nine species including family Ruminococcaceae and genera Faecalibacterium and Eubacterium, in ISS group was significantly lower than that in control group (P<0.05). The relative abundance of 10 species, such as those belonging to genus Parabacteroides and genus Clostridium, in ISS group was significantly higher than that in control group (P<0.05). The concentration of total SCFAs and butyrate in ISS group was significantly lower than that in control group. The correlation analysis among different species, clinical indicators, and SCFAs showed that the relative abundance of family Ruminococcaceae and genera Faecalibacterium and Eubacterium was positively correlated with the standard deviation score of height. Furthermore, the concentrations of total SCFAs and butyrate were positively correlated with serum insulin-like growth factor 1 (IGF-1)-SDS. Disease prediction model constructed based on the bacteria who abundance differed between healthy children and ISS children exhibited high diagnostic value (AUC: 0.88).

CONCLUSIONS

The composition of gut microbiota and the change in its metabolite levels may be related to ISS pathogenesis. Strains with increased or decreased specificity could be used as biomarkers to diagnose ISS.

Gut microbiome is associated with the clinical response to anti-PD-1 based immunotherapy in hepatobiliary cancers

BACKGROUND

The gut microbiome is associated with the response to immunotherapy for different cancers. However, the impact of the gut microbiome on hepatobiliary cancers receiving immunotherapy remains unknown. This study aims to investigate the relationship between the gut microbiome and the clinical response to anti-programmed cell death protein 1 (PD-1) immunotherapy in patients with advanced hepatobiliary cancers.

METHODS

Patients with unresectable hepatocellular carcinoma or advanced biliary tract cancers who have progressed from first-line chemotherapy (gemcitabine plus cisplatin) were enrolled. Fresh stool samples were collected before and during anti-PD-1 treatment and analyzed with metagenomic sequencing. Significantly differentially enriched taxa and prognosis associated taxa were identified. The Kyoto Encyclopedia of Genes and Genomes database and MetaCyc database were further applied to annotate the differentially enriched taxa to explore the potential mechanism of the gut microbiome influencing cancer immunotherapy.

RESULTS

In total, 65 patients with advanced hepatobiliary cancers receiving anti-PD-1 treatment were included in this study. Seventy-four taxa were significantly enriched in the clinical benefit response (CBR) group and 40 taxa were significantly enriched in the non-clinical benefit (NCB) group. Among these taxa, patients with higher abundance of Lachnospiraceae bacterium-GAM79 and Alistipes sp Marseille-P5997, which were significantly enriched in the CBR group, achieved longer progression-free survival (PFS) and overall survival (OS) than patients with lower abundance. Higher abundance of Ruminococcus calidus and Erysipelotichaceae bacterium-GAM147 enriched in the CBR group was also observed in patients with better PFS. In contrast, worse PFS and OS were found in patients with higher abundance of Veillonellaceae, which was significantly enriched in the NCB group. Functional annotation indicated that the taxa enriched in the CBR group were associated with energy metabolism while the taxa enriched in the NCB group were associated with amino acid metabolism, which may modulate the clinical response to immunotherapy in hepatobiliary cancers. In addition, immunotherapy-related adverse events were affected by the gut microbiome diversity and relative abundance.

CONCLUSIONS

We demonstrate that the gut microbiome is associated with the clinical response to anti-PD-1 immunotherapy in patients with hepatobiliary cancers. Taxonomic signatures enriched in responders are effective biomarkers to predict the clinical response and survival benefit of immunotherapy, which might provide a new therapeutic target to modulate the response to cancer immunotherapy.

A new biological triangle in cancer: intestinal microbiota, immune checkpoint inhibitors and antibiotics

Cancer immunotherapy has revolutionized the treatment of many malignant tumors. Although immune checkpoint inhibitors (ICIs) can reactivate the anti-tumor activity of immune cells, sensitivity to immune checkpoint inhibitor therapy depends on the complex tumor immune processes. In recent years, numerous researches have demonstrated the role of intestinal microbiota in immunity and metabolism of the tumor microenvironment, as well as the efficacy of immunotherapy. Epidemiological studies have further demonstrated the efficacy of antibiotic therapy on the probability of patients' response to ICIs and predictability of the short-term survival of cancer patients. Disturbance to the intestinal microbiota significantly affects ICIs-mediated immune reconstitution and is considered a possible mechanism underlying the development of adverse effects during antibiotic-based ICIs treatment. Intestinal microbiota, antibiotics, and ICIs have gradually become important considerations for the titer of immunotherapy. In the case of immunotherapy, the rational use of antibiotics and intestinal microbiota is expected to yield a better prognosis for patients with malignant tumors.

Potential Reasons for Unresponsiveness to Anti-PD1 Immunotherapy in Young Patients with Advanced Melanoma

The impact of age on the clinical benefit of anti-PD1 immunotherapy in advanced melanoma patients has been evolving recently. Due to a reduced immune function in elderly patients, young patients with a robust immune system are theoretically expected to benefit more from the treatment approach. However, in contrast to this hypothesis, recent studies in patients with metastatic melanoma have demonstrated that immunotherapy, especially with anti-PD1 treatment, is less effective in patients below 65 years, on average, with significantly lower responses and reduced overall survival compared to patients above 65 years of age. Besides, data on young patients are even more sparse. Hence, in this review, we will focus on age-dependent differences in the previously described resistance mechanisms to the treatment and discuss the development of potential combination treatment strategies for enhancing the anti-tumor efficacy of anti-PD1 or PDL1 treatment in young melanoma patients.

Directing T-Cell Immune Responses for Cancer Vaccination and Immunotherapy

Cancer vaccination and immunotherapy revolutionised the treatment of cancer, a result of decades of research into the immune system in health and disease. However, despite recent breakthroughs in treating otherwise terminal cancer, only a minority of patients respond to cancer immunotherapy and some cancers are largely refractive to immunotherapy treatment. This is due to numerous issues intrinsic to the tumour, its microenvironment, or the immune system. CD4+ and CD8+ αβ T-cells emerged as the primary effector cells of the anti-tumour immune response but their function in cancer patients is often compromised. This review details the mechanisms by which T-cell responses are hindered in the setting of cancer and refractive to immunotherapy, and details many of the approaches under investigation to direct T-cell function and improve the efficacy of cancer vaccination and immunotherapy.

The Association of Altered Gut Microbiota and Intestinal Mucosal Barrier Integrity in Mice With Heroin Dependence

The gut microbiota is believed to play a significant role in psychological and gastrointestinal symptoms in heroin addicts. However, the underlying mechanism remains largely unknown. We show here that heroin addicts had a decrease in body mass index (BMI) and abnormal serum D-lactic acid (DLA), endotoxin (ET) and diamine oxidase (DAO) levels during their withdrawal stage, suggesting a potential intestinal injury. The gut microbial profiles in the mouse model with heroin dependence showed slightly decreased alpha diversity, as well as higher levels of Bifidobacterium and Sutterella and a decrease in Akkermansia at genus level compared to the control group. Fecal microbiota transplantation (FMT) further confirmed that the microbiota altered by heroin dependence was sufficient to impair body weight and intestinal mucosal barrier integrity in recipient mice. Moreover, short-chain fatty acids (SCFAs) profiling revealed that microbiota-derived propionic acid significantly decreased in heroin dependent mice compared to controls. Overall, our study shows that heroin dependence significantly altered gut microbiota and impaired intestinal mucosal barrier integrity in mice, highlighting the role of the gut microbiota in substance use disorders and the pathophysiology of withdrawal symptoms.

Gut microbiota and its influence on ovarian cancer carcinogenesis, anticancer therapy and surgical treatment: A literature review

Ovarian cancer (OC) is the most lethal gynecological malignancy and very little is known about the underlying tumorigenesis mechanisms. For other tumors, like colorectal cancer, a relationship between several opportunistic pathogens and cancer development and progression has been proven. Recent researches also underline a possible correlation between gut microbiota dysbiosis and cancer treatment efficacy and adverse effects. Several studies have also demonstrated a link between abdominal surgery and gut microbiota modifications. In this paper, we aim to review the available evidences of this issue in OC to understand if there is a relationship between gut microbiota modifications and efficacy and adverse effects of cancer therapies, either surgical and medical treatments. Well-designed clinical studies, with a robust translational component, are required to better understand the modulation of gut microbiota during OC treatment. The microbiota/microbiome composition analysis, in the near future, could represent a novel instrument to personalize anticancer therapies.

Fecal microbiota composition associates with the capacity of human peripheral blood monocytes to differentiate into immunogenic dendritic cells in vitro

Although promising for active immunization in cancer patients, dendritic cells (DCs) vaccines generated in vitro display high inter-individual variability in their immunogenicity, which mostly limits their therapeutic efficacy. Gut microbiota composition is a key emerging factor affecting individuals' immune responses, but it is unknown how it affects the variability of donors' precursor cells to differentiate into immunogenic DCs in vitro. By analyzing gut microbiota composition in 14 healthy donors, along with the phenotype and cytokines production by monocyte-derived DCs, we found significant correlations between immunogenic properties of DC and microbiota composition. Namely, donors who had higher α-diversity of gut microbiota and higher abundance of short-chain fatty acid (SCFAs) and SCFA-producing bacteria in feces, displayed lower expression of CD1a on immature (im)DC and higher expression of ILT-3, costimulatory molecules (CD86, CD40) proinflammatory cytokines (TNF-α, IL-6, IL-8) and IL-12p70/IL-10 ratio, all of which correlated with their lower maturation potential and immunogenicity upon stimulation with LPS/IFNγ, a well-known Th1 polarizing cocktail. In contrast, imDCs generated from donors with lower α-diversity and higher abundance of Bifidobacterium and Collinsella in feces displayed higher CD1a expression and higher potential to up-regulate CD86 and CD40, increase TNF-α, IL-6, IL-8 production, and IL-12p70/IL-10 ratio upon stimulation. These results emphasize the important role of gut microbiota on the capacity of donor precursor cells to differentiate into immunogenic DCs suitable for cancer therapy, which could be harnessed for improving the actual and future DC-based cancer therapies.

Commensal Bifidobacterium Strains Enhance the Efficacy of Neo-Epitope Based Cancer Vaccines

A large body of data both in animals and humans demonstrates that the gut microbiome plays a fundamental role in cancer immunity and in determining the efficacy of cancer immunotherapy. In this work, we have investigated whether and to what extent the gut microbiome can influence the antitumor activity of neo-epitope-based cancer vaccines in a BALB/c-CT26 cancer mouse model. Similarly to that observed in the C57BL/6-B16 model, Bifidobacterium administration per se has a beneficial effect on CT26 tumor inhibition. Furthermore, the combination of Bifidobacterium administration and vaccination resulted in a protection which was superior to vaccination alone and to Bifidobacterium administration alone, and correlated with an increase in the frequency of vaccine-specific T cells. The gut microbiome analysis by 16S rRNA gene sequencing and shotgun metagenomics showed that tumor challenge rapidly altered the microbiome population, with Muribaculaceae being enriched and Lachnospiraceae being reduced. Over time, the population of Muribaculaceae progressively reduced while the Lachnospiraceae population increased—a trend that appeared to be retarded by the oral administration of Bifidobacterium. Interestingly, in some Bacteroidales, Prevotella and Muribaculacee species we identified sequences highly homologous to immunogenic neo-epitopes of CT26 cells, supporting the possible role of “molecular mimicry” in anticancer immunity. Our data strengthen the importance of the microbiome in cancer immunity and suggests a microbiome-based strategy to potentiate neo-epitope-based cancer vaccines.

The potential of fecal microbiota transplantation in oncology

Immune checkpoint inhibitors (ICPIs) are efficacious treatments for several cancers. However, most patients fail to demonstrate durable complete responses. The gut microbiome composition influences the ICPI response. Two recent proof-of-concept studies have demonstrated the utility of fecal microbiota transplantation to transform ICPI responsiveness in refractory patients, providing intriguing evidence for the future of microbiota modulation within oncology.

Probiotic Supplements: Their Strategies in the Therapeutic and Prophylactic of Human Life-Threatening Diseases

Chronic diseases and viral infections have threatened human life over the ages and constitute the main reason for increasing death globally. The rising burden of these diseases extends to negatively affecting the economy and trading globally, as well as daily life, which requires inexpensive, novel, and safe therapeutics. Therefore, scientists have paid close attention to probiotics as safe remedies to combat these morbidities owing to their health benefits and biotherapeutic effects. Probiotics have been broadly adopted as functional foods, nutraceuticals, and food supplements to improve human health and prevent some morbidity. Intriguingly, recent research indicates that probiotics are a promising solution for treating and prophylactic against certain dangerous diseases. Probiotics could also be associated with their essential role in animating the immune system to fight COVID-19 infection. This comprehensive review concentrates on the newest literature on probiotics and their metabolism in treating life-threatening diseases, including immune disorders, pathogens, inflammatory and allergic diseases, cancer, cardiovascular disease, gastrointestinal dysfunctions, and COVID-19 infection. The recent information in this report will particularly furnish a platform for emerging novel probiotics-based therapeutics as cheap and safe, encouraging researchers and stakeholders to develop innovative treatments based on probiotics to prevent and treat chronic and viral diseases.

Microbiome and cancer

The human microbiome constitutes a complex multikingdom community that symbiotically interacts with the host across multiple body sites. Host-microbiome interactions impact multiple physiological processes and a variety of multifactorial disease conditions. In the past decade, microbiome communities have been suggested to influence the development, progression, metastasis formation, and treatment response of multiple cancer types. While causal evidence of microbial impacts on cancer biology is only beginning to be unraveled, enhanced molecular understanding of such cancer-modulating interactions and impacts on cancer treatment are considered of major scientific importance and clinical relevance. In this review, we describe the molecular pathogenic mechanisms shared throughout microbial niches that contribute to the initiation and progression of cancer. We highlight advances, limitations, challenges, and prospects in understanding how the microbiome may causally impact cancer and its treatment responsiveness, and how microorganisms or their secreted bioactive metabolites may be potentially harnessed and targeted as precision cancer therapeutics.

Microbiomics in Collusion with the Nervous System in Carcinogenesis: Diagnosis, Pathogenesis and Treatment

The influence of the naturally occurring population of microbes on various human diseases has been a topic of much recent interest. Not surprisingly, continuously growing attention is devoted to the existence of a gut brain axis, where the microbiota present in the gut can affect the nervous system through the release of metabolites, stimulation of the immune system, changing the permeability of the blood–brain barrier or activating the vagus nerves. Many of the methods that stimulate the nervous system can also lead to the development of cancer by manipulating pathways associated with the hallmarks of cancer. Moreover, neurogenesis or the creation of new nervous tissue, is associated with the development and progression of cancer in a similar manner as the blood and lymphatic systems. Finally, microbes can secrete neurotransmitters, which can stimulate cancer growth and development. In this review we discuss the latest evidence that support the importance of microbiota and peripheral nerves in cancer development and dissemination.

Combining IL-2-based immunotherapy with commensal probiotics produces enhanced antitumor immune response and tumor clearance

Background

Interleukin-2 (IL-2) serves as a pioneer of immunotherapeutic agent in cancer treatment. However, there is a considerable proportion of patients who cannot benefit from this therapy due to the limited clinical responses and dose-limiting toxicities. Mounting evidence indicates that commensal microbiota shapes the outcome of cancer immunotherapies. In this study, we aim to investigate the enhancing effect of Akkermansia muciniphila (AKK), a beneficial commensal microbe receiving considerable attentions, on the antitumor efficacy of IL-2 and explore the underlying molecular mechanism.

Methods

Colorectal carcinoma patient-derived tumor tissues were used to evaluate the therapeutic efficacy of combination treatment. AKK was orally delivered to B16F10 and CT26 tumor-bearing mice along with systemic IL-2 treatment. Flow cytometry was carried out to analyze the tumor immune microenvironment. The molecular mechanism of the enhanced therapeutic efficacy was explored by RNA-seq and then verified in tumor-bearing mice.

Results

Combined treatment with IL-2 and AKK showed a stronger antitumor efficacy in colorectal cancer patient-derived tumor tissues. Meanwhile, the therapeutic outcome of IL-2 was significantly potentiated by oral administration of AKK in subcutaneous melanoma and colorectal tumor-bearing mice, resulting from the strengthened antitumor immune surveillance. Mechanistically, the antitumor immune response elicited by AKK was partially mediated by Amuc, derived from the outer membrane protein of AKK, through activating toll-like receptor 2 (TLR2) signaling pathway. Besides, oral supplementation with AKK protected gut barrier function and maintained mucosal homeostasis under systemic IL-2 treatment.

Conclusion

These findings propose that IL-2 combined with AKK is a novel therapeutic strategy with prospecting application for cancer treatment in clinical practice.

Synbiotics Supplements Lower the Risk of Hand, Foot, and Mouth Disease in Children, Potentially by Providing Resistance to Gut Microbiota Dysbiosis

Background

Hand, foot and mouth disease (HFMD) is an acute enterovirus-induced disease. Gut microbiota dysbiosis has been identified as a factor that plays an important role in enteral virus infection, but the gut microbiota profile in hand, foot and mouth disease has rarely been studied in a large population.

Methods

A total of 749 children (HFMD: n = 262, healthy control: n = 487) aged 2 to 7 years were recruited from hospitals and communities in the period from May to July, 2017. Clinical and demographical information was collected by trained personnel, and fecal samples were collected and processed for 16S ribosomal RNA(rRNA) gene sequencing.

Results

We observed a significant alteration in the microbiota profile of children with HFMD compared with that of control children. Patients with enteroviruses A71(EV71) positive had more dysbiotic gut microbiota than those with coxsackievirus A16 (CAV16) positive. We found that Prevotella and Streptococcus were enriched in children with HFMD, whereas beneficial bacteria, including Bifidobacterium and Faecalibacterium, were depleted. Children with synbiotics supplements had lower risk of HFMD and we observed that the gut microbiota of HFMD patients who were administered synbiotics exhibited potential resistance to the dysbiosis detected in HFMD.

Conclusions

This study suggested that the gut microbiota of patients with hand, foot and mouth disease exhibits dysbiosis and that synbiotics supplements potentially helps maintain the homeostasis of the gut flora.

A new method for investigating microbiota-produced small molecules in adenomatous polyps

The intestinal microbiota is composed of a large number of different bacteria that produce a variety of metabolites. Colorectal cancer, which typically develops from adenomatous polyps, is highly influenced by microbiota. Since a variety of molecular changes may occur as these polyps transform from benign tumor to malignant carcinoma, the ability to study the microbiota-produced metabolites can lead to new discoveries about the development and progression of this cancer. However, to address the complexity of the microbiota-produced molecules, novel methods are needed. To this aim, in the present work, we developed a high-throughput metabolomics method to capture the metabolic complexity of the microbiota metabolome adherent to adenomatous polyps and adenocarcinoma. For the first time, the method enables the simultaneous quantification of almost 300 metabolites, while preserving the integrity of the original sample. The metabolomics approach was analytically validated and had excellent performances in terms of recovery, linearity, specificity, intra- and inter-day precision, limits of detection, and quantification. Furthermore, the clinical potential of the method was demonstrated in adenoma collected for a colorectal adenoma study.

Dysregulation of ILC3s unleashes progression and immunotherapy resistance in colon cancer

Group 3 innate lymphoid cells (ILC3s) regulate immunity and inflammation, yet their role in cancer remains elusive. Here, we identify that colorectal cancer (CRC) manifests with altered ILC3s that are characterized by reduced frequencies, increased plasticity, and an imbalance with T cells. We evaluated the consequences of these changes in mice and determined that a dialog between ILC3s and T cells via major histocompatibility complex class II (MHCII) is necessary to support colonization with microbiota that subsequently induce type-1 immunity in the intestine and tumor microenvironment. As a result, mice lacking ILC3-specific MHCII develop invasive CRC and resistance to anti-PD-1 immunotherapy. Finally, humans with dysregulated intestinal ILC3s harbor microbiota that fail to induce type-1 immunity and immunotherapy responsiveness when transferred to mice. Collectively, these data define a protective role for ILC3s in cancer and indicate that their inherent disruption in CRC drives dysfunctional adaptive immunity, tumor progression, and immunotherapy resistance.

Commensal bacteria and fungi differentially regulate tumor responses to radiation therapy

Studies suggest that the efficacy of cancer chemotherapy and immunotherapy is influenced by intestinal bacteria. However, the influence of the microbiome on radiation therapy is not as well understood, and the microbiome comprises more than bacteria. Here, we find that intestinal fungi regulate antitumor immune responses following radiation in mouse models of breast cancer and melanoma and that fungi and bacteria have opposite influences on these responses. Antibiotic-mediated depletion or gnotobiotic exclusion of fungi enhances responsiveness to radiation, whereas antibiotic-mediated depletion of bacteria reduces responsiveness and is associated with overgrowth of commensal fungi. Further, elevated intratumoral expression of Dectin-1, a primary innate sensor of fungi, is negatively associated with survival in patients with breast cancer and is required for the effects of commensal fungi in mouse models of radiation therapy.

The Challenge of ICIs Resistance in Solid Tumours: Could Microbiota and Its Diversity Be Our Secret Weapon?

The human microbiota and its functional interaction with the human body were recently returned to the spotlight of the scientific community. In light of the extensive implementation of newer and increasingly precise genome sequencing technologies, bioinformatics, and culturomic, we now have an extraordinary ability to study the microorganisms that live within the human body. Most of the recent studies only focused on the interaction between the intestinal microbiota and one other factor. Considering the complexity of gut microbiota and its role in the pathogenesis of numerous cancers, our aim was to investigate how microbiota is affected by intestinal microenvironment and how microenvironment alterations may influence the response to immune checkpoint inhibitors (ICIs). In this context, we show how diet is emerging as a fundamental determinant of microbiota’s community structure and function. Particularly, we describe the role of certain dietary factors, as well as the use of probiotics, prebiotics, postbiotics, and antibiotics in modifying the human microbiota. The modulation of gut microbiota may be a secret weapon to potentiate the efficacy of immunotherapies. In addition, this review sheds new light on the possibility of administering fecal microbiota transplantation to modulate the gut microbiota in cancer treatment. These concepts and how these findings can be translated into the therapeutic response to cancer immunotherapies will be presented.

Intestinal microbiota influences clinical outcome and side effects of early breast cancer treatment

The prognosis of early breast cancer (BC) relies on cell autonomous and immune parameters. The impact of the intestinal microbiome on clinical outcome has not yet been evaluated. Shotgun metagenomics was used to determine the composition of the fecal microbiota in 121 specimens from 76 early BC patients, 45 of whom were paired before and after chemotherapy. These patients were enrolled in the CANTO prospective study designed to record the side effects associated with the clinical management of BC. We analyzed associations between baseline or post-chemotherapy fecal microbiota and plasma metabolomics with BC prognosis, as well as with therapy-induced side effects. We examined the clinical relevance of these findings in immunocompetent mice colonized with BC patient microbiota that were subsequently challenged with histo-compatible mouse BC and chemotherapy. We conclude that specific gut commensals that are overabundant in BC patients compared with healthy individuals negatively impact BC prognosis, are modulated by chemotherapy, and may influence weight gain and neurological side effects of BC therapies. These findings obtained in adjuvant and neoadjuvant settings warrant prospective validation.

Peripheral Blood Lymphocyte Percentage May Predict Chemotolerance and Survival in Patients with Advanced Pancreatic Cancer. Association between Adaptive Immunity and Nutritional State

Pancreatic Carcinoma (PC) cells have the ability to induce patient immunosuppression and to escape immunosurveillance. Low circulating lymphocytes are associated with an advanced stage of PC and reduced survival. Blood lymphocytes expressed as a percentage of Total White Blood Cells (L% TWBC) could predict chemotolerance (n° of tolerated cycles), survival time and Body Weight (BW) more effectively than lymphocytes expressed as an absolute value (LAB > 1500 n°/mm3) or lymphocytes >22%, which is the lowest limit of normal values in our laboratory. Forty-one patients with advanced PC, treated with chemotherapy, were selected for this observational retrospective study. Patients were evaluated at baseline (pre-chemotherapy), and at 6, 12 and 18 months, respectively, after diagnosis of PC. The study found L ≥ 29.7% to be a better predictor of survival (COX model, using age, sex, BW, serum creatinine, bilirubin and lymphocytes as covariates), chemotolerance (r = +0.50, p = 0.001) and BW (r = +0.35, p = 0.027) than LAB > 1500 or L > 22%. BW did not significantly correlate with chemotolerance or survival. The preliminary results of this study suggest that L ≥ 29.7% is more effective than LAB > 1500 or L > 22% at predicting chemotolerance, survival time and nutritional status. A possible impact of nutritional status on chemotherapy and survival seems to be lymphocyte-mediated given the association between BW and L%. This study may serve as the basis for future research to explore whether nutritional interventions can improve lymphopenia, and if so, how this may be possible.

Microbiota-Centered Interventions: The Next Breakthrough in Immuno-Oncology?

The cancer-immune dialogue subject to immuno-oncological intervention is profoundly influenced by microenvironmental factors. Indeed, the mucosal microbiota-and more specifically, the intestinal ecosystem-influences the tone of anticancer immune responses and the clinical benefit of immunotherapy. Antibiotics blunt the efficacy of immune checkpoint inhibitors (ICI), and fecal microbial transplantation may restore responsiveness of ICI-resistant melanoma. Here, we review the yin and yang of intestinal bacteria at the crossroads between the intestinal barrier, metabolism, and local or systemic immune responses during anticancer therapies. We discuss diagnostic tools to identify gut dysbiosis and the future prospects of microbiota-based therapeutic interventions. SIGNIFICANCE: Given the recent proof of concept of the potential efficacy of fecal microbial transplantation in patients with melanoma primarily resistant to PD-1 blockade, it is timely to discuss how and why antibiotics compromise the efficacy of cancer immunotherapy, describe the balance between beneficial and harmful microbial species in play during therapies, and introduce the potential for microbiota-centered interventions for the future of immuno-oncology.

Harness the functions of gut microbiome in tumorigenesis for cancer treatment

It has been shown that gut microbiota dysbiosis leads to physiological changes and links to a number of diseases, including cancers. Thus, many cancer categories and treatment regimens should be investigated in the context of the microbiome. Owing to the availability of metagenome sequencing and multiomics studies, analyses of species characterization, host genetic changes, and metabolic profile of gut microbiota have become feasible, which has facilitated an exponential knowledge gain about microbiota composition, taxonomic alterations, and host interactions during tumorigenesis. However, the complexity of the gut microbiota, with a plethora of uncharacterized host‐microbe, microbe‐microbe, and environmental interactions, still contributes to the challenge of advancing our knowledge of the microbiota‐cancer interactions. These interactions manifest in signaling relay, metabolism, immunity, tumor development, genetic instability, sensitivity to cancer chemotherapy and immunotherapy. This review summarizes current studies/molecular mechanisms regarding the association between the gut microbiota and the development of cancers, which provides insights into the therapeutic strategies that could be harnessed for cancer diagnosis, treatment, or prevention.

Gut microbiota signatures are associated with toxicity to combined CTLA-4 and PD-1 blockade

Treatment with combined immune checkpoint blockade (CICB) targeting CTLA-4 and PD-1 is associated with clinical benefit across tumor types, but also a high rate of immune-related adverse events. Insights into biomarkers and mechanisms of response and toxicity to CICB are needed. To address this, we profiled the blood, tumor and gut microbiome of 77 patients with advanced melanoma treated with CICB, with a high rate of any ≥grade 3 immune-related adverse events (49%) with parallel studies in pre-clinical models. Tumor-associated immune and genomic biomarkers of response to CICB were similar to those identified for ICB monotherapy, and toxicity from CICB was associated with a more diverse peripheral T-cell repertoire. Profiling of gut microbiota demonstrated a significantly higher abundance of Bacteroides intestinalis in patients with toxicity, with upregulation of mucosal IL-1β in patient samples of colitis and in pre-clinical models. Together, these data offer potential new therapeutic angles for targeting toxicity to CICB.

Regulation and Functions of Protumoral Unconventional T Cells in Solid Tumors

The vast majority of studies on T cell biology in tumor immunity have focused on peptide-reactive conventional T cells that are restricted to polymorphic major histocompatibility complex molecules. However, emerging evidence indicated that unconventional T cells, including γδ T cells, natural killer T (NKT) cells and mucosal-associated invariant T (MAIT) cells are also involved in tumor immunity. Unconventional T cells span the innate-adaptive continuum and possess the unique ability to rapidly react to nonpeptide antigens via their conserved T cell receptors (TCRs) and/or to activating cytokines to orchestrate many aspects of the immune response. Since unconventional T cell lineages comprise discrete functional subsets, they can mediate both anti- and protumoral activities. Here, we review the current understanding of the functions and regulatory mechanisms of protumoral unconventional T cell subsets in the tumor environment. We also discuss the therapeutic potential of these deleterious subsets in solid cancers and why further feasibility studies are warranted.