Targeting the gut and tumor microbiota in cancer

Advances in clinical immunotherapy for gastric cancer.

The transformative success of antibodies targeting the PD-1 (programmed death 1)/B7-H1 (B7 homolog 1) pathway (anti-PD therapy) has revolutionized cancer treatment. However, only a fraction of patients with solid tumors and some hematopoietic malignancies respond to anti-PD therapy, and the reason for failure in other patients is less known. By dissecting the mechanisms underlying this resistance, current studies reveal that the tumor microenvironment is a major location for resistance to occur. Furthermore, the resistance mechanisms appear to be highly heterogeneous. Here, we discuss recent human cancer data identifying mechanisms of resistance to anti-PD therapy. We review evidence for immune-based resistance mechanisms such as loss of neoantigens, defects in antigen presentation and interferon signaling, immune inhibitory molecules, and exclusion of T cells. We also review the clinical evidence for emerging mechanisms of resistance to anti-PD therapy, such as alterations in metabolism, microbiota, and epigenetics. Finally, we discuss strategies to overcome anti-PD therapy resistance and emphasize the need to develop additional immunotherapies based on the concept of normalization cancer immunotherapy.

Resistance Mechanisms to Anti-PD Cancer Immunotherapy.

Microenvironment-driven metabolic adaptations guiding CD8+ T cell anti-tumor immunity.

Immune checkpoint inhibitor-related cardiotoxicity is one of the most lethal adverse effects, and thus, the identification of underlying mechanisms for developing strategies to overcome it has clinical importance. This study aimed to investigate whether microbiota-host interactions contribute to PD-1/PD-L1 inhibitor-related cardiotoxicity.A mouse model of immune checkpoint inhibitor-related cardiotoxicity was constructed by PD-1/PD-L1 inhibitor BMS-1 (5 and 10 mg/kg), and cardiomyocyte apoptosis and cardiotoxicity were determined by hematoxylin and eosin, Masson's trichome and TUNEL assays. 16S rRNA sequencing was used to define the gut microbiota composition. Gut microbiota metabolites short-chain fatty acids (SCFAs) were determined by HPLC. The serum levels of myocardial enzymes (creatine kinase, aspartate transaminase, creatine kinase-MB and lactate dehydrogenase) and the production of M1 factors (TNF-α and IL-1β) were measured by ELISA. The colonic macrophage phenotype was measured by mmunofluorescence and qPCR. The expression of Claudin-1, Occludin, ZO-1 and p-p65 was measured by western blot. The gene expression of peroxisome proliferator-activated receptor α (PPARα) and cytochrome P450 (CYP) 4X1 was determined using qPCR. Statistical analyses were performed using Student's t-test for two-group comparisons, and one-way ANOVA followed by Student-Newman-Keul test for multiple-group comparisons.We observed intestinal barrier injury and gut microbiota dysbiosis characterized by Prevotellaceae and Rikenellaceae genus depletion and Escherichia-Shigella and Ruminococcaceae genus enrichment, accompanied by low butyrate production and M1-like polarization of colonic macrophages in BMS-1 (5 and 10 mg/kg)-induced cardiotoxicity. Fecal microbiota transplantation mirrored the effect of BMS-1 on cardiomyocyte apoptosis and cardiotoxicity, while macrophage depletion and neutralization of TNF-α and IL-1β greatly attenuated BMS-1-induced cardiotoxicity. Importantly, Prevotella loescheii recolonization and butyrate supplementation alleviated PD-1/PD-L1 inhibitor-related cardiotoxicity. Mechanistically, gut microbiota dysbiosis promoted M1-like polarization of colonic macrophages and the production of proinflammatory factors TNF-α and IL-1β through downregulation of PPARα-CYP4X1 axis.Intestinal barrier dysfunction amplifies PD-1/PD-L1 inhibitor-related cardiotoxicity by upregulating proinflammatory factors TNF-α and IL-1β in colonic macrophages via downregulation of butyrate-PPARα-CYP4X1 axis. Thus, targeting gut microbiota to polarize colonic macrophages away from the M1-like phenotype could provide a potential therapeutic strategy for PD-1/PD-L1 inhibitor-related cardiotoxicity. 

/pdf/prevotellaceae-produces-butyrate-to-alleviate-pd-1-pd-l1-22qlauvn.pdf

Prevotellaceae produces butyrate to alleviate PD-1/PD-L1 inhibitor-related cardiotoxicity via PPARα-CYP4X1 axis in colonic macrophages

We report on a comprehensive analysis of the gut microbiomes of patients with gastrointestinal (GI) cancer receiving anti-PD-1/PD-L1 treatment. The human gut microbiota has been associated with clinical responses to anti-PD-1/PD-L1 immunotherapy in melanoma, non-small cell lung cancer, and renal cell carcinoma. We aimed to investigate this association in GI cancers. We also identified bacterial taxa with patient stratification potential. We recruited 74 patients with advanced-stage GI cancer receiving anti-PD-1/PD-L1 treatment and collected their fecal samples prior to and during immunotherapy, along with clinical evaluations. Our 16S rRNA taxonomy survey on the fecal samples revealed an elevation of the Prevotella/Bacteroides ratio in patients, with a preferred response to anti-PD-1/PD-L1 treatment, and a particular subgroup of responders harboring a significantly higher abundance of Prevotella, Ruminococcaceae, and Lachnospiraceae The shotgun metagenomes of the same samples showed that patients exhibiting different responses had differential abundance of pathways related to nucleoside and nucleotide biosynthesis, lipid biosynthesis, sugar metabolism, and fermentation to short-chain fatty acids (SCFA). Gut bacteria that were capable of SCFA production, including Eubacterium, Lactobacillus, and Streptococcus, were positively associated with anti-PD-1/PD-L1 response across different GI cancer types. We further demonstrated that the identified bacterial taxa were predictive of patient stratification in both our cohort and melanoma patients from two previously published studies. Our results thus highlight the impact of gut microbiomes on anti-PD-1/PD-L1 outcomes, at least in a subset of patients with GI cancer, and suggest the potential of the microbiome as a marker for immune-checkpoint blockade responses.See articles by Tomita et al., p. 1236, and Hakozaki et al., p. 1243.

/pdf/the-gut-microbiome-is-associated-with-clinical-response-to-4z6ykoyhrx.pdf

The Gut Microbiome Is Associated with Clinical Response to Anti-PD-1/PD-L1 Immunotherapy in Gastrointestinal Cancer.

We report the first and largest cohort, to the best of our knowledge, on the gut microbiome of 126 gastrointestinal (GI) cancer patients in China receiving the immune checkpoint inhibitors (ICI) targeting PD-1. The cohort included 31 patients with colon cancer, 23 with esophageal carcinoma, 47 with gastric cancer, and 25 with other cancer types. 43 of the patients had samples collected before treatment. 35 of patients were assessed as microsatellite-instability-High (MSI-High) and 71 as non-MSI-High. 408 fecal samples from the patients were collected. We performed 16s rRNA amplicon sequencing (V4 region) of the patients9 samples to investigate the relationship between microbial profiles and patients9 immunotherapy treatment response (RECIST 1.1). Principal coordinate analysis (PCoA) showed a subgroup of responders exhibiting a microbiome profile which was enriched in Prevotella. Hierarchical clustering of patients9 microbiome profiles also suggested that for each gastric and colon cancer, patients with the same response tend to share similar microbiome profiles. By comparing the microbiome profiles between R and NR group using samples collected before treatment or within 3 weeks since the start of treatment, we identified 16s rRNA V4 sequences from Prevotella enriched in R group for each tumor type, which suggests positive association between Prevotella and tumor response. Our data also suggested that MSI as good marker for tumor response, although more data is required to achieve the significance level. Besides, no significant difference in alpha diversity was observed between R and NR group for each tumor type. In sum, we studied the microbiome profiles of 126 GI cancer patients and evaluated their association with anti-PD-1 immunotherapy. Patients with the same tumor type and response tend to share similar microbiome profiles, where Prevotella and a few other taxa contributed to the pattern. Citation Format: Zhi Peng, Siyuan Cheng, Quan Zhang, Yan Kou, Ziqi Wang, Rong Jin, Han Hu, Xiaotian Zhang, Jifang Gong, Jian Li, Ming Lu, Xicheng Wang, Jun Zhou, Zhihao Lu, Dongtao Bi, Yan Tan, Lin Shen. The gut microbiome is associated with clinical responses to anti-PD-1 immunotherapy in gastrointestinal cancer patients in China [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4298.

Abstract 4298: The gut microbiome is associated with clinical responses to anti-PD-1 immunotherapy in gastrointestinal cancer patients in China

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Han Hu

Author Tools

Chat about Author

Papers

The Gut Microbiome Is Associated with Clinical Response to Anti-PD-1/PD-L1 Immunotherapy in Gastrointestinal Cancer.

Abstract 4298: The gut microbiome is associated with clinical responses to anti-PD-1 immunotherapy in gastrointestinal cancer patients in China