Intratumoral microbial heterogeneity affected tumor immune microenvironment and determined clinical outcome of HBV-related HCC

Microecological regulation in HCC therapy: Gut microbiome enhances ICI treatment

The exploration of the complex mechanisms of cancer immunotherapy is rapidly evolving worldwide, and our focus is on the interaction of hepatocellular carcinoma (HCC) with immune checkpoint inhibitors (ICIs), particularly as it relates to the regulatory role of the gut microbiome. An important basis for the induction of immune responses in HCC is the presence of specific anti-tumor cells that can be activated and reinforced by ICIs, which is why the application of ICIs results in sustained tumor response rates in the majority of HCC patients. However, mechanisms of acquired resistance to immunotherapy in unresectable HCC result in no long-term benefit for some patients. The significant heterogeneity of inter-individual differences in the gut microbiome in response to treatment with ICIs makes it possible to target modulation of specific gut microbes to assist in augmenting checkpoint blockade therapies in HCC. This review focuses on the complex relationship between the gut microbiome, host immunity, and HCC, and emphasizes that manipulating the gut microbiome to improve response rates to cancer ICI therapy is a clinical strategy with unlimited potential.

Understanding gut dysbiosis for hepatocellular carcinoma diagnosis and treatment

The gut microbiome can play a crucial role in hepatocellular carcinoma (HCC) progression through the enterohepatic circulation, primarily acting via metabolic reprogramming and alterations in the hepatic immune microenvironment triggered by microbe-associated molecular patterns (MAMPs), metabolites, and fungi. In addition, the gut microbiome shows potential as a biomarker for early HCC diagnosis and for assessing the efficacy of immunotherapy in unresectable HCC. This review examines how gut microbiota dysbiosis, with varied functional profiles, contributes to HCCs of different etiologies. We discuss therapeutic strategies to modulate the gut microbiome including diets, antibiotics, probiotics, fecal microbiota transplantation, and nano-delivery systems, and underscore their potential as an adjunctive treatment modality for HCC.

Pan-cancer atlas of tumor-resident microbiome, immunity and prognosis

The existence of microbiome in human tumors has been determined widely, but evaluating the contribution of intratumoral bacteria and fungi to tumor immunity and prognosis from a pan-cancer perspective remains absent. We designed an improved microbial analysis pipeline to reduce interference from host sequences, complemented with integration analysis of intratumoral microbiota at species level with clinical indicators, tumor microenvironment, and prognosis across cancer types. We found that intratumoral microbiota is associated with immunophenotyping, with high-immunity subtypes showing greater bacterial and fungal richness compared to low-immunity groups. We also noted that the combination of fungi and bacteria demonstrated promising prognostic value across cancer types. We, thus, present The Cancer Microbiota (TCMbio), an interactive platform that provides the intratumoral bacteria and fungi data, and a comprehensive analysis module for 33 types of cancers. This led to the discovery of clinical and prognostic significance of intratumoral microbes.

Association between ascites Gustave Roussy immune score and the intratumoural microbiome in malignant ascites secondary to hepatocellular carcinoma

BACKGROUNDS

The Gustave Roussy Immune (GRIm) score predicts survival outcomes in several cancers. However, the prognostic significance of the GRIm score in patients with malignant ascites has not yet been investigated.

METHODS

Clinical samples were collected from a cohort of patients with malignant ascites secondary to hepatocellular carcinoma (HCC). We calculated serum GRIm (sGRIm) and ascites GRIm (aGRIm) scores and divided the samples into low and high GRIm score groups. Survival analysis was used to compare the prognostic significance of the sGRIm and aGRIm scores. 16S rRNA sequencing was performed to determine the profiles of the intratumoral microbiota in the groups. A fluorescent multiplex immunohistochemistry (mIHC) assay was used to detect the expression of different immune cells by labeling seven markers of malignant ascites.

RESULTS

155 patients with HCC and malignant ascites were enrolled in this study. Survival analysis revealed that the aGRIm score showed a superior prognostic significance compared to the sGRIm score. Microbial analysis demonstrated that the bacterial richness and diversity were higher in the low aGRIm score group than in the high aGRIm score group. LefSe analysis revealed that certain bacteria were correlated with high aGRIm scores. Fluorescent mIHC displayed the tumor microenvironment of malignant ascites and found that the density of CD8 + T cells was significantly higher in the low aGRIm score group than in the high aGRIm score group.

CONCLUSIONS

Our present study identified a novel scoring system (aGRIm score) that can predict the survival outcome of patients with malignant ascites secondary to HCC.

Broadening oncological boundaries: the intratumoral microbiota

The microbiota of solid tumors was identified >100 years ago; however, heterogeneous composition and diversity have been revealed only recently. Growing evidence has suggested that several functional mechanisms of the intratumoral microbiota affect tumorigenesis and progression, suggesting that the intratumoral microbiota is a promising biomarker for multiple cancers. The low biomass of the intratumoral microbiota poses a major challenge to related research, thus necessitating the use of a multiple-modality integrated framework to resolve this dilemma. Advanced techniques such as single-cell sequencing provide significant clues, and the gradual optimization of functional experiments and culture-based methods enables deeper investigation of the underlying mechanisms involved. In this review, we outline the current state of research on the intratumoral microbiota and describe the challenges and comprehensive strategies for future research.

The microbiome and rise of early-onset cancers: knowledge gaps and research opportunities

Accumulating evidence indicates an alarming increase in the incidence of early-onset cancers, which are diagnosed among adults under 50 years of age, in the colorectum, esophagus, extrahepatic bile duct, gallbladder, liver, stomach, pancreas, as well as the bone marrow (multiple myeloma), breast, head and neck, kidney, prostate, thyroid, and uterine corpus (endometrium). While the early-onset cancer studies have encompassed research on the wide variety of organs, this article focuses on research on digestive system cancers. While a minority of early-onset cancers in the digestive system are associated with cancer-predisposing high penetrance germline genetic variants, the majority of those cancers are sporadic and multifactorial. Although potential etiological roles of diets, lifestyle, environment, and the microbiome from early life to adulthood (i.e. in one's life course) have been hypothesized, exact contribution of each of these factors remains uncertain. Diets, lifestyle patterns, and environmental exposures have been shown to alter the oral and intestinal microbiome. To address the rising trend of early-onset cancers, transdisciplinary research approaches including lifecourse epidemiology and molecular pathological epidemiology frameworks, nutritional and environmental sciences, multi-omics technologies, etc. are needed. We review current evidence and discuss emerging research opportunities, which can improve our understanding of their etiologies and help us design better strategies for prevention and treatment to reduce the cancer burden in populations.