Influence of the gut microbiota on the response to immunotherapy in hepatocellular carcinoma

The gut microbiota plays a role in triggering innate immunity and regulating the immune microenvironment (IME) of hepatocellular carcinoma (HCC) by acting on various signaling receptors and transcription factors through its metabolites and related molecules. Furthermore, there is an increasing recognition of the gut microbiota as a potential therapeutic target for HCC, given its ability to modulate the efficacy of immune checkpoint inhibitors (ICIs). This review will discuss the mechanisms of gut microbiota in modulating immunotherapy of HCC, the predictive value of efficacy, and the therapeutic strategies for modulating the gut microbiota in detail. We conducted a systematic literature search in PubMed, Embase, Scopus, Cochrane Library, China National Knowledge Infrastructure, and Wanfang Chinese databases for articles involving the influence of gut microbiota on HCC immunotherapy. The mechanisms underlying the effect of gut microbiota on HCC immunotherapy include gut-liver axis, tumor immune microenvironment (TIME), and antibodies. Patients who benefit from ICIs exhibit a higher abundance of gut microbiota. Antibiotics, fecal microbiota transplantation (FMT), probiotics, and prebiotics are effective methods to regulate gut microbiota. The strong connection between the liver and gut will provide numerous opportunities for the development of microbiome-based diagnostics, treatments, or prevention strategies for HCC patients.

TPS407 Background: Renal cell carcinoma (RCC) is the 6° most common cancer in men and the 8° in women in the USA. In Italy RCC incidence was 11,500 new cases in 2017, while mortality was 3,371 cases in 2015. Increasing evidence suggests that response to immune checkpoint inhibitors (ICIs), a novel treatment for advanced RCC (aRCC) and other epithelial tumors, can be influenced by the patient gut microbiota. Fecal microbiota transplantation (FMT) is a novel treatment option aimed to restore healthy gut microbiota, and is the most effective therapy for recurrent C. difficile infection. Preliminary nonrandomized findings show that FMT is able to improve efficacy of ICIs in patients with advanced melanoma. The aim of this study is to evaluate, through a double-blinded placebo-controlled randomized clinical trial, the efficacy of targeted FMT (from donors who are responding to ICIs) in improving response rates to ICIs in subjects with aRCC. Methods: 50 patients who are about to receive, or have started by <8 weeks, pembrolizumab + axitinib as first-line therapy for aRCC will be enrolled. Exclusion criteria include major comorbidities, concomitant GI or autoimmune disorders, or HIV, HBV, HCV infection, continuative corticosteroid therapy, previous treatment with systemic immune-suppressants or immune-modulatory drugs, antibiotic therapy within 4 weeks prior to enrollment. Stool samples and clinical data will be collected at baseline. Then, patients will be randomized to donor FMT or placebo FMT. They will receive the first infusion by colonoscopy and then oral frozen fecal or placebo capsules (8 capsules t.i.d.) 90 and 180 days after the first FMT. Stool donors will be searched among long-term (>12 months) responders to ICIs, and will be selected by following protocols recommended by international guidelines. Patients in the FMT group will always receive feces from the same donor throughout the three fecal transplants. Frozen fecal batches and frozen fecal capsules will be manufactured according to international guidelines. Patients will be followed-up 7, 15, 30, 90, 180, 270, and 360 days after randomization for clinical evaluation and collection of stool samples. Patients will also undergo radiological assessment at 90, 180, 270 and 360 days after randomization. Microbiome analysis will be performed with shotgun metagenomics. The primary endpoint is the progression-free survival (PFS) at 12 months. Secondary endpoints are: objective response rate at 12 months; overall survival at 12 months; adverse events after FMT; microbiome changes after FMT. Sample size calculation was based on the hypothesis that FMT can improve the 1-year PFS rate from 60% (reported 1-year PFS for SOC) to 80% wen associated to SOC. Clinical trial information: NCT04758507.

Glioblastoma (GBM) is a highly malignant, invasive, and poorly prognosed brain tumor. Unfortunately, active comprehensive treatment does not significantly prolong patient survival. With the deepening of research, it has been found that gut microbiota plays a certain role in GBM, and can directly or indirectly affect the efficacy of immune checkpoint inhibitors (ICIs) in various ways. (1) The metabolites produced by gut microbiota directly affect the host's immune homeostasis, and these metabolites can affect the function and distribution of immune cells, promote or inhibit inflammatory responses, affect the phenotype, angiogenesis, inflammatory response, and immune cell infiltration of GBM cells, thereby affecting the effectiveness of ICIs. (2) Some members of the gut microbiota may reverse T cell function inhibition, increase T cell anti-tumor activity, and ultimately improve the efficacy of ICIs by targeting specific immunosuppressive metabolites and cytokines. (3) Some members of the gut microbiota directly participate in the metabolic process of drugs, which can degrade, transform, or produce metabolites, affecting the effective concentration and bioavailability of drugs. Optimizing the structure of the gut microbiota may help improve the efficacy of ICIs. (4) The gut microbiota can also regulate immune cell function and inflammatory status in the brain through gut brain axis communication, indirectly affecting the progression of GBM and the therapeutic response to ICIs. (5) Given the importance of gut microbiota for ICI therapy, researchers have begun exploring the use of fecal microbiota transplantation (FMT) to transplant healthy or optimized gut microbiota to GBM patients, in order to improve their immune status and enhance their response to ICI therapy. Preliminary studies suggest that FMT may enhance the efficacy of ICI therapy in some patients. In summary, gut microbiota plays a crucial role in regulating ICIs in GBM, and with a deeper understanding of the relationship between gut microbiota and tumor immunity, it is expected to develop more precise and effective personalized ICI therapy strategies for GBM, in order to improve patient prognosis.

The gut microbiota is often altered in chronic liver diseases and hepatocellular carcinoma (HCC), and increasing evidence suggests that it may influence response to cancer immunotherapy. Strategies to modulate the gut microbiome (i.e., fecal microbiota transplant (FMT)) may help to improve efficacy of immune checkpoint inhibitors (ICIs) or even overcome resistance to ICIs. Here, we describe the design and rationale of FAB-HCC, a single-center, single-arm, phase II pilot study to assess safety, feasibility, and efficacy of FMT from patients with HCC who responded to PD-(L)1-based immunotherapy or from healthy donors to patients with HCC who failed to achieve or maintain a response to atezolizumab plus bevacizumab. In this single-center, single-arm, phase II pilot study (ClinicalTrials.gov identifier: NCT05750030), we plan to include 12 patients with advanced HCC who failed to achieve or maintain a response to atezolizumab/bevacizumab. Patients will receive a single FMT via colonoscopy from donors with HCC who responded to PD-(L)1-based immunotherapy or from healthy individuals, followed by atezolizumab/bevacizumab every 3 weeks. The primary endpoint is safety, measured by incidence and severity of treatment-related adverse events. The main secondary endpoint is efficacy, as assessed by best radiological response according to RECISTv1.1 and mRECIST. Additional exploratory endpoints include data on the effect of FMT on recipient gut microbiota, as well as metagenomic analysis of stool samples, analyses of circulating immune cells and serum and stool proteomic, metabolomic and lipidomic signatures. The results of this study will help to define the potential of FMT as add-on intervention in the systemic treatment of advanced HCC, with the potential to improve efficacy of immunotherapy or even overcome resistance. EudraCT Number: 2022-000234-42 Clinical trial registry & ID: ClinicalTrials.gov identifier: NCT05750030 (Registration date: 16.01.2023).

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

Hepatocellular carcinoma (HCC), a primary malignancy of the liver and leading cause of cancer-related mortality worldwide, poses substantial therapeutic challenges, particularly in advanced and unresectable stages. Immune checkpoint inhibitors (ICIs) have emerged as critical therapeutic agents, targeting immune checkpoint pathways to restore antitumor immune responses. Combinations such as atezolizumab (anti-programmed cell death ligand 1 with bevacizumab (anti-vascular endothelial growth factor), as well as antibodies directed against cytotoxic T-lymphocyte associated protein 4 and programmed cell death protein 1 (e.g., ipilimumab and nivolumab), have demonstrated improved clinical outcome in selected patients. However, the overall efficacy of ICIs remains hindered by variable response rate and primary or acquired resistance. Recent evidence suggests that the gut microbiome plays a pivotal role in modulating host immune responses and may significantly influence the therapeutic efficacy of ICIs. Dysbiosis within the gut-liver axis has been implicated not only in pathogenesis and progression of HCC but also diminishing immunotherapy effectiveness. Emerging studies highlight the potential of microbiome-targeted interventions including dietary modulation, prebiotics, probiotics, and fecal microbiota transplantation to enhance ICIs responsiveness. This review explores the evolving interplay between the gut microbiota and immunotherapy in HCC, with a focus on microbiome-based strategies aimed at optimizing clinical outcomes.

e16175 Background: The safety and efficacy of immune checkpoint inhibitors (ICI) in Child-Pugh (CP)-B and CP-C hepatocellular carcinoma (HCC) patients remain uncertain. In a multidisciplinary system a considerable number of patients will belong to this population and do not qualify for standard of care ICI-based regimens. This study presents a retrospective review of ICI in this specific population at our institution. Methods: This study included HCC patients who received at least one ICI dose between 1/1/2017 and 6/30/23 at Ohio State University. Clinical and pathological characteristics of interest were extracted through chart review. Survival outcomes assessed in this study include progression-free survival (PFS; date of first dose of ICI (Fd-ICI) to progression or death (D) or loss of follow-up (L-f/u)), overall survival (OS; date of diagnosis to D or L-f/u), and ICI-specific OS (OS-ICI; Fd-ICI to D or L-f/u). Kaplan-Meier methods were used to estimate PFS, OS-ICI, and OS survival distributions. Median survival times were calculated and compared between groups using the Wilcoxon test. Results: We had 25 patients (19 CP-B and 6 CP-C) in the study cohort (SC) with a median age of 67 years (range: 48-84), 72% males and 88% Caucasians. Most of them (96%) had ascites, and 40% had hepatic encephalopathy at the time of ICI initiation. Seven patients had tyrosine kinase inhibitors, and 15 had local therapy (LT) before ICI. Most received single-agent ICI (n = 17), while 8 had it combined with bevacizumab (BEV). Median doses of ICI for the group were 3 (range, 1-25) and were better in CP-B (4, 1-25) than in CP C (1, 1-4) population. The group's median PFS, OS-ICI, and OS (in days) were 159, 222, and 439, respectively. The CP-B subgroup had better median PFS (242 vs. 41 days, p = 0.0002) and median OS-ICI (235 vs. 50 days, p = 0.0046) than CP-C. However, the median OS had no significant difference (497 vs. 290 days, p = 0.4). BEV combination improved the OS-ICI (242 vs. 127 days, p = 0.04) but not PFS or OS for the SC (CP-B + C). Additionally, ICI in the second line or more (583 vs. 244, p = 0.02) and specifically after LT (575 vs. 252 days, p = 0.02) improved the OS of this study cohort. Similar findings were noted in the CP-B subgroup (line - 575 vs. 252 days, p = 0.02 and LT - 678 vs. 293 days, p = 0.02). Only two patients experienced grade 3 immune-related adverse events (dermatitis and colitis); no complications were associated with BEV. Conclusions: ICIs can be safely and effectively used in CP-B patients with advanced HCC, particularly after LT and in second-line or later settings. CP-C patients derive limited benefit, highlighting the need for cautious selection. Combining BEV with ICIs is safe and may offer survival benefits in this challenging population.

This study was designed to investigate the efficacy and safety of immune checkpoint inhibitors (ICIs) in advanced hepatocellular carcinoma (HCC). Electronic databases were scanned to identify relevant trials. The primary endpoints were overall survival (OS), progression-free survival (PFS), and their prognostic factors. Stratified analyses were accomplished on ICIs agent and evaluation criteria. Totally, 3697 individuals from 40 cohorts were recruited. For patients treated with ICIs, the pooled median time to progression (TTP) was 8.0 months, median PFS 4.9 months, and median OS 12.0 months; the pooled median PFS and OS of ICIs plus anti-vascular endothelial growth factor (VEGF) agents (PFS: 6.3 months, OS: 16.4 months) were longer than those of ICIs alone. Furthermore, Child-Pugh stage (HR = 1.37, P = 0.0123) and Eastern Cooperative Oncology Group (ECOG) (HR = 1.40, P = 0.0016) were prognostic factors for PFS. Hepatitis C virus (HCV) (HR = 0.71, P = 0.0356), Alpha-fetoprotein (AFP) (HR = 1.17, P < 0.0001), Child-Pugh stage (HR = 1.58, P < 0.0001), Barcelona Clinic Liver Cancer (BCLC) stage (HR = 1.23, P = 0.0005), ECOG (HR = 1.50, P = 0.0012), portal vein invasion (HR = 1.32, P = 0.0053), extrahepatic metastasis (HR = 0.84, P = 0.0047), best response (HR = 0.58, P < 0.0001), and neutrophil-to-lymphocyte ratio (NLR) (HR = 1.23, P = 0.0451) were the prognostic factors for OS. According to both RECIST 1.1 and mRECIST, the objective response rate (ORR) and disease control rate (DCR) rate of ICIs plus anti-VEGF agents were better than those of ICIs alone. The overall rate of any grade adverse events (AEs) was 0.76 (95% CI 0.61-0.89), grade 3 or higher AEs was 0.28 (95% CI 0.15-0.42), and the rate of AEs leading to treatment discontinuation was 0.09 (95% CI 0.06-0.12). The ICIs was promising in HCC with good efficacy and tolerated toxicity. Compared with ICIs monotherapy, the joint application of ICIs and anti-VEGF agents can contribute a lot more benefits to the survival of patients according to clinical practices.

Impact of gut-microbiome altering drugs and fecal microbiota transplant on the efficacy and toxicity of immune checkpoint inhibitors: A systematic review

BackgroundGut microbiome has been associated with the efficacy of immune checkpoint inhibitors (ICI) in patients with various types of cancers but not yet in hepatocellular carcinoma (HCC).AimsTo investigate the association between gut microbiome and efficacy of ICI in patients with HCC.MethodsPatients with HCC who were scheduled to receive ICI were prospectively enrolled. Fecal samples were collected within 7 days before initiation of ICI (baseline) and 8 weeks later. Gut microbiome was assessed using 16S rRNA sequencing and shotgun whole-genome sequencing and correlated with objective response (complete or partial response), disease control (objective response or stable disease for ≥16 weeks), and overall survival.ResultsThirty-six patients with HCC were enrolled, and 20 of them provided both baseline and 8-week feces. Alpha diversity, richness, and compositions of baseline gut microbiome indicated no difference between responders and nonresponders or between disease control and nondisease control groups. For the 20 paired feces, immunotherapy did not change any of the major microbiome features. No specific taxa were enriched in patients with objective response. Three taxa—Bifidobacterium, Coprococcus, and Acidaminococcus—were enriched in patients with disease control. However, the baseline abundance of these three taxa did not predict overall survival benefit.ConclusionsIn this exploratory study, we failed to disclose any overt association of gut microbiome with the efficacy of ICI in patients with HCC. A larger prospective study is warranted for definite conclusion.

Historically, tumor burden has been considered an impediment to efficacy of immunotherapeutic agents, including vaccines, stem cell transplant, cytokine therapy, and intravesical bacillus Calmette-Guérin. This effect has been attributed to hypoxic zones in the tumor core contributing to poor T-cell infiltration, formation of immunosuppressive stromal cells, and development of therapy-resistant cell populations. However, the association between tumor burden and efficacy of immune checkpoint inhibitors is unknown. We sought to determine the association between radiographic tumor burden parameters and efficacy of immune checkpoint inhibitors in advanced lung cancer. We performed a retrospective analysis of patients with advanced lung cancer treated with immune checkpoint inhibitors. Demographic, disease, and treatment data were collected. Serial tumor dimensions were recorded according to RECIST version 1.1. Associations between radiographic tumor burden (baseline sum of longest diameters, longest single diameter) and clinical outcomes (radiographic response, progression-free survival, and overall survival) were determined using log-rank tests, Cox proportional-hazard regression, and logistic regression. Among 105 patients, the median baseline sum of longest diameters (BSLD) was 6.4 cm; median longest single diameter was 3.6 cm. BSLD was not associated with best radiographic, progression-free survival, or overall survival. In univariate and multivariate analyses, no significant associations were observed for the other radiographic parameters and outcomes when considered as categorical or continuous variables. Although tumor burden has been considered a mediator of efficacy of earlier immunotherapies, in advanced lung cancer it does not appear to affect outcomes from immune checkpoint inhibitors. Historically, tumor burden has been considered an impediment to the efficacy of various immunotherapies, including vaccines, cytokines, allogeneic stem cell transplant, and intravesical bacillus Calmette-Guérin. However, in the present study, no association was found between tumor burden and efficacy (response rate, progression-free survival, overall survival) of immune checkpoint inhibitors in advanced lung cancer. These findings suggest that immune checkpoint inhibitors may provide benefit across a range of disease burden, including bulky tumors considered resistant to other categories of immunotherapy.

The systemic treatment of hepatocellular carcinoma (HCC) is changing rapidly. After a decade of tyrosine kinase inhibitors (TKIs), as the only therapeutic option for the treatment of advanced HCC, in the last few years several phase III trials demonstrated the efficacy of immune checkpoint inhibitors (ICIs). The combination of the anti-PD-L1 atezolizumab and the anti-vascular endothelial growth factor (VEGF) bevacizumab demonstrated the superiority over sorafenib and currently represents the standard of care treatment for advanced HCC. In addition, the combination of durvalumab (an anti-PD-L1) and tremelimumab (an anti-CTLA4) proved to be superior to sorafenib, and in the same trial durvalumab monotherapy showed non-inferiority compared to sorafenib. However, early reports suggest an influence of HCC etiology in modulating the response to these drugs. In particular, a lower effectiveness of ICIs has been suggested in patients with non-viral HCC (in particular non-alcoholic fatty liver disease). Nevertheless, randomized controlled trials available to date have not been stratified for etiology and data suggesting a possible impact of etiology in the outcome of patients managed with ICIs derive from subgroup not pre-specified analyses. In this review, we aim to examine the potential impact of HCC etiology on the response to immunotherapy regimens for HCC.

Gut microbiome metabolites, molecular mimicry, and species-level variation drive long-term efficacy and adverse event outcomes in lung cancer survivors

Immune checkpoint inhibitors have dramatically revolutionized the therapeutic landscape for patients with advanced malignancies. Recently, convincing evidence has shown meaningful influence of gut microbiome on human immune system. With the complex link between gut microbiome, host immunity and cancer, the variations in the gut microbiota may influence the efficacy of immune checkpoint inhibitors. Indeed, some bacterial species have been reported to be predictive for cancer outcome in patients treated with immune checkpoint inhibitors. Although immune checkpoint inhibitors are currently proven to be an effective anti-tumor treatment, they can induce a distinct form of toxicity, termed immune-related adverse events. Immune-related colitis is one of the common toxicities from immune checkpoint inhibitors, and it might preclude the cancer therapy in severe or refractory cases. The manipulation of gut microbiome by fecal microbiota transplantation or probiotics administration has been suggested as one of the methods to enhance anti-tumor effects and decrease the risk of immune-related colitis. Here we review the role of gut microbiome on immune checkpoint inhibitor therapy and consequent immune-related colitis to provide a new insight for better anti-cancer therapy.

The gut microbiota, a complex microbial ecosystem closely connected to the liver via the portal vein, has emerged as a critical regulator of liver health and disease. Numerous studies have underscored its role in the onset and progression of liver disorders, including alcoholic liver disease, metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction-associated steatohepatitis (MASH), liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). This review provides a comprehensive overview of current insights into the influence of the gut microbiota on HCC progression, particularly its effects on immune cells within the HCC tumor microenvironment (TME). Furthermore, we explore the potential of gut microbiota-targeted interventions, such as antibiotics, probiotics, prebiotics, and fecal microbiota transplantation (FMT), to modulate the immune response and improve outcomes of immunotherapy in HCC. By synthesizing insights from recent studies, this review aims to highlight microbiota-based strategies that may enhance immunotherapy outcomes, advancing personalized approaches in HCC treatment.