Antibiotics are associated with decreased progression-free survival of advanced melanoma patients treated with immune checkpoint inhibitors

Gastrointestinal toxicities associated with immune checkpoint inhibitors therapy: risks and management

Immune checkpoint inhibitors (ICIs) have greatly improved cancer treatment by boosting the immune system's ability to target tumors. However, they can also cause serious side effects, particularly in the digestive system. These include immune-related diarrhea, inflammation of the intestines and, less commonly, inflammation of the stomach or esophagus. This review underscores the importance of early detection, accurate diagnosis, and timely treatment to improve patient outcomes. It also highlights the need for further research to develop strategies to reduce gastrointestinal toxicities and enhance the overall effectiveness of ICIs in cancer therapy.

Antibiotics use decreases survival in cutaneous squamous cell carcinoma patients receiving immune checkpoint inhibitors

INTRODUCTION

Immune checkpoint inhibitors (ICI) have become the first-line therapy in patients with advanced cutaneous squamous cell carcinoma (cSCC). Antibiotics (ATB) have been reported to reduce ICI response in cancers, but this has not been evaluated in cSCC.

AIM

To evaluate ATB exposure at the onset of ICI in cSCC patients and to analyze its impact on outcome.

METHODS

This single-center retrospective study included all patients who started anti-PD-1 for cSCC between March 2019 and July 2023. Exposure to ATB within 3 months prior and after the onset of ICI (ATB 3-3), including patients exposed within 1 month prior and after (ATB 1-1) were recorded. Response to ICI and survival were compared between patients with or without ATB exposure.

RESULTS

Among 104 patients included, 45 % were classified into ATB 3-3 subgroup, and 20 % to ATB 1-1. Disease control rate at 3 months were lower in both ATB 1-1 and ATB 3-3 subgroups, compared to their control group (p = 0.02 and 0.03, respectively). The overall survival and disease specific survival were lower in the ATB 1-1 subgroup, compared to control group (p = 0.04 and p = 0.01, respectively). Median progression free survival was 127 days in ATB 1-1 group, significantly lower than the control group (not reached), p = 0.005.

CONCLUSION

ATB intake was very frequent at ICI initiation in cSCC patients. In our cohort, ATB use within 1 month before or after ICI initiation significantly impacted survival, highlighting the need for caution when prescribing antibiotics in this population.

Prophylactic antibiotic use is associated with better clinical outcomes in gastric cancer patients receiving immunotherapy

BACKGROUND

The relationship between antibiotic treatment and immunotherapy efficacy is complex.

METHODS

This study was a single-center study. History of antibiotic use in gastric cancer (GC) patients within 1 or 3 months prior to immunotherapy was collected. Patients were categorized into 3 groups according to whether they had used antibiotics prior to immunotherapy: none, prophylactic use, and infection.

RESULTS

A total of 252 GC patients received immunotherapy, of which 38.5% (97/252) received antibiotic treatment within 1 month before immunotherapy (prophylactic use in 72.2% of patients) and 48.8% (123/252) received antibiotic treatment within 3 months before immunotherapy (prophylactic use in 74.8% of patients). The prophylactic use of antibiotic within 1 month prior to immunotherapy significantly improved overall survival (OS) compared with patients who received anti-infective therapy and had no history of antibiotic use (prophylactic vs infection: OS, 22.6 vs 9.7 m, HR, 0.53, 95% CI, 0.27-1.07; prophylactic vs none: OS, 22.6 vs 14.7 m, HR, 0.57; 95% CI, 0.39-0.83). The use of antibiotics in infected patients did not increase the risk of death in patients compared with those who did not use antibiotics. Prophylactic antibiotic use within 1 month before immunotherapy is an independent prognostic factor for OS.

CONCLUSIONS

Prophylactic use of antibiotics is associated with better prognosis in GC patients receiving immunotherapy. Therefore, there is no necessity to delay the use of immune checkpoint inhibitors in this group of patients.

Intra-tumoral bacteria in breast cancer and intervention strategies

The microbiome, consisting of a wide range of both beneficial and harmful microorganisms, is vital to various physiological and pathological processes in the human body, including cancer pathogenesis. Tumor progression is often accompanied by the destruction of the vascular system, allowing bacteria to circulate into the tumor area and flourish in an immunosuppressive environment. Microbes are recognized as significant components of the tumor microenvironment. Recent research has increasingly focused on the role of intra-tumoral bacteria in the onset, progression, and treatment of breast cancer-the most prevalent cancer among women. This review elucidates the potential mechanisms by which intra-tumoral bacteria impact breast cancer and discusses different therapeutic approaches aimed at targeting these bacteria. It provides essential insights for enhancing existing treatment paradigms while paving the way for novel anticancer interventions. As our understanding of the microbiome's intricate relationship with cancer deepens, it opens avenues for groundbreaking strategies that could redefine oncology.

The Relationship Between the Modulation of Intestinal Microbiota and the Response to Immunotherapy in Patients with Cancer

The intestinal microbiota is an important part of the human body, and its composition can affect the effectiveness of immunotherapy. In the last few years, the modulation of intestinal microbiota in order to improve the effectiveness of immunotherapy has become a current topic in the scientific community, but there is a lack of research in this area. In this review, the goal was to analyze the current relevant literature related to the modulation of intestinal microbiota and the effectiveness of immunotherapy in the treatment of cancer. The effects of antibiotics, probiotics, diet, and fecal microbial transplantation were analyzed separately. It was concluded that the use of antibiotics, especially broad-spectrum types or larger quantities, causes dysbiosis of the intestinal microbiota, which can reduce the effectiveness of immunotherapy. While dysbiosis could be repaired by probiotics and thus improve the effectiveness of immunotherapy, the use of commercial probiotics without evidence of intestinal dysbiosis has not yet been sufficiently tested to confirm its safety for cancer for immunotherapy-treated cancer patients. A diet consisting of sufficient amounts of fiber, as well as a diet with higher salt content positively correlates with the success of immunotherapy. Fecal transplantation is a safe and realistic adjuvant option for the treatment of cancer patients with immunotherapy, but more clinical trials are necessary. Modulating the microbiota composition indeed changes the effectiveness of immunotherapy, but in the future, more human studies should be organized to precisely determine the types and procedures of microbiota modulation.

Microbiome and Immunotherapy for Melanoma: Are We Ready for Clinical Application?

The microbiome plays a substantial role in the efficacy of immune checkpoint blockade (ICB) in patients with metastatic melanoma. While the exact gut microbiome composition and the pathways involved in this interaction are not clearly delineated, novel studies and ongoing clinical trials are likely to reveal findings applicable to the clinical setting for the prediction and optimization of response to ICB. Nevertheless, lifestyle modifications, including high fiber diet, avoidance of unnecessary antibiotic prescriptions, and careful use of probiotics may be helpful to optimize the "health" of the gut microbiome and potentially enhance response to ICB in patients with melanoma.

The DAV132 colon-targeted adsorbent does not interfere with plasma concentrations of antibiotics but prevents antibiotic-related dysbiosis: a randomized phase I trial in healthy volunteers

The deleterious impact of antibiotics (ATB) on the microbiome negatively influences immune checkpoint inhibitors (ICI) response in patients with cancer. We conducted a randomized phase I study (EudraCT:2019-A00240-57) with 148 healthy volunteers (HV) to test two doses of DAV132, a colon-targeted adsorbent, alongside intravenous ceftazidime-avibactam (CZA), piperacillin-tazobactam (PTZ) or ceftriaxone (CRO) and a group without ATB. The primary objective of the study was to assess the effect of DAV132 on ATB plasma concentrations and both doses of DAV132 did not alter ATB levels. Secondary objectives included safety, darkening of the feces, and fecal ATB concentrations. DAV132 was well tolerated, with no severe toxicity and similar darkening at both DAV132 doses. DAV132 led to significant decrease in CZA or PTZ feces concentration. When co-administered with CZA or PTZ, DAV132 preserved microbiome diversity, accelerated recovery to baseline composition and protected key commensals. Fecal microbiota transplantation (FMT) in preclinical cancer models in female mice from HV treated with CZA or PTZ alone inhibited anti-PD-1 response, while transplanted samples from HV treated with ATB + DAV132 circumvented resistance to anti-PD-1. This effect was linked to activated CD8+ T cell populations in the tumor microenvironment. DAV132 represents a promising strategy for overcoming ATB-related dysbiosis and further studies are warranted to evaluate its efficacy in cancer patients.

The role of the microbiome in immune checkpoint inhibitor colitis and hepatitis

Immune checkpoint inhibitors have revolutionised management for a variety of different types of malignancies. However, gastrointestinal adverse effects, in particular colitis and hepatitis, are relatively common with up to 30 % of patients being affected. The gut microbiome has emerged as a potential contributor to both the effectiveness of immune checkpoint inhibitors and their side effects. This review will attempt to examine the impact the microbiome has on adverse effects as a result of immune checkpoint inhibitors as well as the potential for manipulation of the microbiome as a form of management for immune mediated colitis.

Modulating the gut microbiome in non-small cell lung cancer: Challenges and opportunities

Despite the efficacy of immunotherapy in non-small cell lung cancer (NSCLC), the majority of the patients experience relapse with limited subsequent treatment options. Preclinical studies of various epithelial tumors, such as melanoma and NSCLC, have shown that harnessing the gut microbiome resulted in improvement of therapeutic responses to immunotherapy. Is this review, we summarize the role of microbiome, including lung and gut microbiome in the context of NSCLC, provide overview of the mechanisms of microbiome in efficacy and toxicity of chemotherapies and immunotherapies, and address current ongoing clinical trials for NSCLC including fecal microbiota transplantation (FMT) and live biotherapeutic products (LBPs).

Antibiotics are associated with worse outcomes in lung cancer patients treated with chemotherapy and immunotherapy

Anti-PD(L)-1 inhibition combined with platinum doublet chemotherapy (Chemo-IO) has become the most frequently used standard of care regimen in patients with non-small cell lung cancer (NSCLC). The negative impact of antibiotics on clinical outcomes prior to anti-PD(L)-1 inhibition monotherapy (IO) has been demonstrated in multiple studies, but the impact of antibiotic exposure prior to initiation of Chemo-IO is controversial. We assessed antibiotic exposures at two time windows: within 60 days prior to therapy (-60 d window) and within 60 days prior to therapy and 42 days after therapy (-60 + 42d window) in 2028 patients with advanced NSCLC treated with Chemo-IO and IO monotherapy focusing on objective response rate (ORR: rate of partial response and complete response), progression-free survival (PFS), and overall survival (OS). We also assessed impact of antibiotic exposure in an independent cohort of 53 patients. Univariable and multivariable analyses were conducted along with a meta-analysis from similar studies. For the -60 d window, in the Chemo-IO group (N = 769), 183 (24%) patients received antibiotics. Antibiotic exposure was associated with worse ORR (27% vs 40%, p = 0.001), shorter PFS (3.9 months vs. 5.9 months, hazard ratio [HR] 1.35, 95%CI 1.1,1.6, p = 0.0012), as well as shorter OS (10 months vs. 15 months, HR 1.50, 95%CI 1.2,1.8, p = 0.00014). After adjusting for known prognostic factors in NSCLC, antibiotic exposure was independently associated with worse PFS (HR 1.39, 95%CI 1.35,1.7, p = 0.002) and OS (HR 1.61, 95%CI 1.28,2.03, p < 0.001). Similar results were obtained in the -60 + 42d window, and also in an independent cohort. In a meta-analysis of patients with NSCLC treated with Chemo-IO (N = 4) or IO monotherapy (N = 13 studies) antibiotic exposure before treatment was associated with worse OS among all patients (n = 11,351) (HR 1.93, 95% CI 1.52, 2.45) and Chemo-IO-treated patients (n = 1201) (HR 1.54, 95% CI 1.28, 1.84). Thus, antibiotics exposure prior to Chemo-IO is common and associated with worse outcomes, even after adjusting for other factors. These results highlight the need to implement antibiotic stewardship in routine oncology practice.

The impact of antibiotic use in gastrointestinal tumors treated with immune checkpoint inhibitors: systematic review and meta-analysis

Background

Immune checkpoint inhibitors (ICI) have improved overall survival in patients with different cancer types. However, treatment efficacy varies between patients depending on several factors. Recent research suggested that antibiotic-induced dysbiosis can impair ICI efficacy. Here we review the impact of antibiotic use in clinical outcome of patients with gastrointestinal cancer treated with ICI.

Methods

This is a systematic review and utilized a thorough search of MEDLINE, Cochrane, Scopus, EB-SCO, Web of Science of studies published till September 2023. The aim of the study is to determine the association between antibiotic use and ICI treatment efficacy in patients with gastrointestinal cancers (GI). We utilized a meta-analysis of the association between the use of antibiotics and overall survival and progression-free survival.

Results

Nine studies met the inclusion criteria with a total of 2,214 patients. The most common type of cancers was hepatocellular carcinoma (HCC). The majority of the studies were retrospective, and one was collective of clinical trials. The use of antibiotics was associated with decreased both overall survival [haz-ard ratio (HR) 1.92, 95% confidence interval (CI) 1.41, 2.63] and progression-free survival [HR 1.81, 95% CI 1.29, 2.54].

Conclusion

The use of antibiotics may affect clinical outcomes in patients with GI cancers treated with ICI. Further prospective studies are needed to improve the understanding of this phenomenon.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023462172.

Long-term relapse-free survival enabled by integrating targeted antibacteria in antitumor treatment

The role of tumor-resident intracellular microbiota (TRIM) in carcinogenesis has sparked enormous interest. Nevertheless, the impact of TRIM-targeted antibacteria on tumor inhibition and immune regulation in the tumor microenvironment (TME) remains unexplored. Herein, we report long-term relapse-free survival by coordinating antibacteria with antitumor treatment, addressing the aggravated immunosuppression and tumor overgrowth induced by TRIM using breast and prostate cancer models. Combining Ag+ release with a Fenton-like reaction and photothermal conversion, simultaneous bacteria killing and multimodal antitumor therapy are enabled by a single agent. Free of immune-stimulating drugs, the agent restores antitumor immune surveillance and activates immunological responses. Secondary inoculation and distal tumor analysis confirm lasting immunological memory and systemic immune responses. A relapse-free survival of >700 days is achieved. This work unravels the crucial role of TRIM-targeted antibacteria in tumor inhibition and unlocks an unconventional route for immune regulation in TME and a complete cure for cancer.

A Review of Practice-Changing Therapies in Oncology in the Era of Personalized Medicine

In the past decade, a lot of insight was gathered into the composition of the host and tumor factors that promote oncogenesis and treatment resistance. This in turn has led to the ingenious design of multiple new classes of drugs, which have now become the new standards of care in cancer therapy. These include novel antibody-drug conjugates, chimeric antigen receptor T cell therapies (CAR-T), and bispecific T cell engagers (BitTE). Certain host factors, such as the microbiome composition, are also emerging not only as biomarkers for the response and toxicity to anti-cancer therapies but also as potentially useful tools to modulate anti-tumor responses. The field is slowly moving away from one-size-fits-all treatment options to personalized treatments tailored to the host and tumor. This commentary aims to cover the basic concepts associated with these emerging therapies and the promises and challenges to fight cancer.

Association of antibiotic treatment with survival outcomes in treatment-naïve melanoma patients receiving immune checkpoint blockade

PURPOSE

The interaction of gut microbiome and immune system is being studied with increasing interest. Disturbing factors, such as antibiotics may impact the immune system via gut and interfere with tumor response to immune checkpoint blockade (ICB).

METHODS

In this multicenter retrospective cohort study exclusively treatment-naïve patients with cutaneous or mucosal melanoma treated with first-line anti-PD-1 based ICB for advanced, non-resectable disease between 06/2013 and 09/2018 were included. Progression-free (PFS), and overall survival (OS) according to antibiotic exposure (within 60 days prior to ICB and after the start of ICB vs. no antibiotic exposure) were analyzed. To account for immortal time bias, data from patients with antibiotics during ICB were analyzed separately in the time periods before and after start of antibiotics.

RESULTS

Among 578 patients with first-line anti-PD1 based ICB, 7% of patients received antibiotics within 60 days prior to ICB and 19% after starting ICB. Antibiotic exposure prior to ICB was associated with worse PFS (adjusted HR 1.75 [95% CI 1.22-2.52]) and OS (adjusted HR 1.64 [95% CI 1.04-2.58]) by multivariate analysis adjusting for potential confounders. The use of antibiotics after the start of ICB had no effect on either PFS (adjusted HR 1.19; 95% CI 0.89-1.60) or OS (adjusted HR 1.08; 95% CI 0.75-1.57).

CONCLUSIONS

Antibiotic exposure within 60 days prior to ICB seems to be associated with worse PFS and OS in melanoma patients receiving first-line anti-PD1 based therapy, whereas antibiotics after the start of ICB do not appear to affect PFS or OS.

Proton pump inhibitors and potassium competitive acid blockers decrease pembrolizumab efficacy in patients with metastatic urothelial carcinoma

We elucidated the efficacy of gut microbiome-altering drugs on pembrolizumab efficacy in patients with metastatic urothelial carcinoma (mUC). Clinical data were analyzed retrospectively from 133 patients with mUC who received second-line pembrolizumab therapy between January 2018 and January 2021, following failed platinum-based chemotherapy. We evaluated the effects of gut microbiome-altering drugs (proton pump inhibitors [PPI]/potassium-competitive acid blockers [P-CAB], H2 blockers, antibiotics, non-steroidal anti-inflammatory drugs [NSAIDs], metformin, antipsychotics, steroids, and opioids), taken by patients within 30 days before/after pembrolizumab treatment, on progression-free survival (PFS) and overall survival (OS). Fifty-one patients received PPI/P-CAB (37/14, respectively); H2 blockers, 7; antibiotics, 35; NSAIDs, 22; antipsychotics, 8; metformin, 3; steroids, 11; and opioids, 29. Kaplan-Meier curves revealed PPI or P-CAB users showed shorter PFS than non-PPI-P-CAB users (p = 0.001, p = 0.005, respectively). Multivariate analysis highlighted PPI/P-CAB use as the only independent prognostic factor for disease progression (hazards ratio: 1.71, 95% confidence interval: 1.14-2.07, p = 0.010) but not death (p = 0.177). Proton pump inhibitors/potassium-competitive acid blockers may decrease the efficacy of pembrolizumab therapy for mUC, possibly via gut microbiome modulation.

Promising and Minimally Invasive Biomarkers: Targeting Melanoma

The therapeutic landscape of malignant melanoma has been radically reformed in recent years, with novel treatments emerging in both the field of cancer immunotherapy and signalling pathway inhibition. Large-scale tumour genomic characterization has accurately classified malignant melanoma into four different genomic subtypes so far. Despite this, only somatic mutations in BRAF oncogene, as assessed in tumour biopsies, has so far become a validated predictive biomarker of treatment with small molecule inhibitors. The biology of tumour evolution and heterogeneity has uncovered the current limitations associated with decoding genomic drivers based only on a single-site tumour biopsy. There is an urgent need to develop minimally invasive biomarkers that accurately reflect the real-time evolution of melanoma and that allow for streamlined collection, analysis, and interpretation. These will enable us to face challenges with tumour tissue attainment and process and will fulfil the vision of utilizing "liquid biopsy" to guide clinical decisions, in a manner akin to how it is used in the management of haematological malignancies. In this review, we will summarize the most recent published evidence on the role of minimally invasive biomarkers in melanoma, commenting on their future potential to lead to practice-changing discoveries.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The impact of antibiotic and proton pump inhibitor use at the time of adjuvant platinum-based chemotherapy on survival in patients with endometrial cancer

OBJECTIVE

We sought to assess the impact of antibiotic (ABX) and proton-pump inhibitor (PPI) use on progression-free (PFS) and overall survival (OS) in patients treated with adjuvant platinum-based chemotherapy (PC) for endometrial cancer (EC).

METHODS

A retrospective, single-institution cohort study of EC patients treated with ≥four cycles of adjuvant PC following surgical staging from 2014 to 2020. Demographics and clinicopathologic features, including ABX and PPI use, were compared using χ2 and Fisher's exact tests. Univariate and multivariable analyses were performed, and survival outcomes were compared using the log-rank test.

RESULTS

Of 325 patients, 95 (29%) received ABX, and 80 (24.6%) received PPI. ABX were associated with decreased 3-year PFS (49.9% vs. 66%; p = 0.0237) but not 3-year OS (68.9% vs. 79.9%; p = 0.0649). ABX targeting gram-positive bacteria were associated with decreased 3-year PFS (21.2% vs. 66.0% vs. 55.4%; p = 0.0038) and 3-year OS (36.5% vs. 79.9% vs. 75.6%; p = 0.0014) compared to no ABX and other ABX, respectively. PPI use was associated with decreased 3-year PFS (46.9% vs. 66.0%; p = 0.0001) and 3-year OS (60.7% vs. 81.9%; p = 0.0041) compared to no PPI. On multivariable regression analysis controlling for confounders including stage, histology, grade, radiation, and co-morbidities, PPI use was independently associated with worse PFS (HR 1.96, 95% CI 1.25-3.08; p = 0.0041) and OS (HR 2.06, 95% CI 1.01-4.18, p = 0.04).

CONCLUSION

In this retrospective cohort study, we demonstrate that PPI use is independently associated with worse PFS and OS in patients with EC treated with PC. ABX use was associated with worse PFS on univariate analysis only. There is an unmet need to understand how PPI, ABX, and, potentially, the microbiome impact the effectiveness of chemotherapy in EC patients.

Biomarker-Driven Personalization of Neoadjuvant Immunotherapy in Melanoma

The introduction of immunotherapy has ushered in a new era of anticancer therapy for many cancer types including melanoma. Given the increasing development of novel compounds and combinations and the investigation in earlier disease stages, the need grows for biomarker-based treatment personalization. Stage III melanoma is one of the front-runners in the neoadjuvant immunotherapy field, facilitating quick biomarker identification by its immunogenic capacity, homogeneous patient population, and reliable efficacy readout. In this review, we discuss potential biomarkers for response prediction to neoadjuvant immunotherapy, and how the neoadjuvant melanoma platform could pave the way for biomarker identification in other tumor types.

SIGNIFICANCE

In accordance with the increasing rate of therapy development, the need for biomarker-driven personalized treatments grows. The current landscape of neoadjuvant treatment and biomarker development in stage III melanoma can function as a poster child for these personalized treatments in other tumors, assisting in the development of new biomarker-based neoadjuvant trials. This will contribute to personalized benefit-risk predictions to identify the most beneficial treatment for each patient.

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

BACKGROUND

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

METHODS

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

FINDINGS

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

INTERPRETATION

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

FUNDING

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

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

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

Gut microbiome on immune checkpoint inhibitor therapy and consequent immune-related colitis: a review

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.

Akkermansia muciniphila: A potential target and pending issues for oncotherapy

In the wake of the development of metagenomic, metabolomic, and metatranscriptomic approaches, the intricate interactions between the host and various microbes are now being progressively understood. Numerous studies have demonstrated evident changes in gut microbiota during the process of a variety of diseases, such as diabetes, obesity, aging, and cancers. Notably, gut microbiota is viewed as a potential source of novel therapeutics. Currently, Next-generation probiotics (NGPs) are gaining popularity as therapeutic agents that alter the gut microbiota and affect cancer development. Akkermansia muciniphila (A. muciniphila), a representative commensal bacterium, has received substantial attention over the past decade as a promising NGP. The components and metabolites of A. muciniphila can directly or indirectly affect tumorigenesis, in particular through its effects on antitumor immunosurveillance, including the stimulation of pattern recognition receptors (PRRs), which also leads to better outcomes in a variety of situations, including the prevention and curation of cancers. In this article, we systematically summarize the role of A. muciniphila in tumorigenesis (involving gastrointestinal and non-gastrointestinal cancers) and in tumor therapy. In particular, we carefully discuss some critical scientific issues that need to be solved for the future using A. muciniphila as a representative beneficial bacterium in tumor treatment, which might provide bright clues and assistance for the application of drugs targeting A. muciniphila in clinical oncotherapy.

Effect of antibiotic treatment on immune checkpoint inhibitors efficacy in patients with advanced non-small cell lung cancer

BACKGROUND

Gut microbiotaplays a crucial role in immune response. Recent data have shown that antibiotic (ATB) usage influences efficacy of immune check point inhibitors (ICIs) via altering microbiota of the gut.

METHODS

We retrospectively analyzed patients with advanced non-small cell lung cancer (NSCLC) treated with ICIs as monotherapy or combination with chemotherapy (ChT) at the one academic center. Those receiving ATB for the first 12 weeks of the initiation of ICIs were compared with those who did not. The primary objective of this study was to assess the impact of ATB use on overall survival (OS), progression-free survival (PFS), and objective response rate (ORR) during ICIs therapy.

RESULTS

90 patients were included in our analysis. Of these 90 patients, 27 (30%) received ATB in the first 12 weeks of the treatment. In patients who received ATB in the first 12 weeks of ICIs administration, PFS was significantly shorter (4.9 vs. 24.8 months, HR 2.52, 95% CI (1.52-4.18), p < 0.001). OS was also significantly shorter (5.4 vs. 37.8 months, HR 2.55, 95% CI (1.48-4.40), p = 0.001). We also examined the impact of ATB on ORR. Exposure to ATB for the first weeks consistently worsened the response rate; the ORR was 25.9% in the ATB group and 55.6% in the no ATB group (p = 0.01).

CONCLUSION

Our findings demonstrated that the use of antibiotics around ICIs initiation was associated with decreased OS, PFS, and ORR in patients with NSCLC. This suggests that microbiota diversity may be one of the factors predicting the efficacy of ICIs.

Checkpoint inhibitor responses can be regulated by the gut microbiota - A systematic review

BACKGROUND

Evidence suggests that the human gut microbiota modulates the treatment response of immune checkpoint inhibitors (ICI) in cancer. Thus, finding predictive biomarkers in the fecal gut microbiota of patients who are less likely to respond to ICI would be valuable. This systematic review aimed to investigate the association between fecal gut microbiota composition and ICI-treatment response in patients with cancer.

METHODS

EMBASE, Medline, and Cochrane Library databases were searched using the "Participants, Interventions, Comparisons, and Outcomes" (PICO) process to locate studies including participants with solid cancers treated with ICI intervention. The comparator was the gut microbiota, and the outcomes were oncological outcomes such as response rates and progression-free survival. Study data were synthesized qualitatively in a systematic narrative synthesis, and the risk of bias in the studies was assessed.

RESULTS

Two reviewers screened 2092 abstracts independently, and 140 studies were read as full-text reports and assessed for eligibility. Eighteen studies were included with 775 patients with different types of solid cancers who received anti-PD-1, anti-PD-L1, or anti-CTLA-4 therapy. Distinct patterns were observed in the patients' fecal samples. Some bacterial species were reported to be present in responders and non-responders, while others were present only in one group. The most reported species associated with better prognosis were Faecalibacterium prausnitzii, Streptococcus parasanguinis, Bacteroides caccae, and Prevotella copri. In contrast, the most reported species associated with poor prognosis were Blautia obeum and Bacteroides ovatus.

CONCLUSION

Distinct microbiota features were associated with good and poor prognoses in ICI-treated patients with cancer.

The Microbiome in Advanced Melanoma: Where Are We Now?

PURPOSE OF REVIEW

This review summarizes recent data linking gut microbiota composition to ICI outcomes and gut microbiota-specific interventional clinical trials in melanoma.

RECENT FINDINGS

Preclinical and clinical studies have demonstrated the effects of the gut microbiome modulation upon ICI response in advanced melanoma, with growing evidence supporting the ability of the gut microbiome to restore or improve ICI response in advanced melanoma through dietary fiber, probiotics, and FMT. Immune checkpoint inhibitors (ICI) targeting the PD-1, CTLA-4, and LAG-3 negative regulatory checkpoints have transformed the management of melanoma. ICIs are FDA-approved in advanced metastatic disease, stage III resected melanoma, and high-risk stage II melanoma and are being investigated more recently in the management of high-risk resectable melanoma in the peri-operative setting. The gut microbiome has emerged as an important tumor-extrinsic modulator of both response and immune-related adverse event (irAE) development in ICI-treated cancer in general, and melanoma in particular.

Gut microbiome and nutrition-related predictors of response to immunotherapy in cancer: making sense of the puzzle

The gut microbiome is emerging as an important predictor of response to immune checkpoint inhibitor (ICI) therapy for patients with cancer. However, several nutrition-related patient characteristics, which are themselves associated with changes in gut microbiome, are also prognostic markers for ICI treatment response and survival. Thus, increased abundance of Akkermansia muciniphila, Phascolarctobacterium, Bifidobacterium and Rothia in stool are consistently associated with better response to ICI treatment. A. muciniphila is also more abundant in stool in patients with higher muscle mass, and muscle mass is a strong positive prognostic marker in cancer, including after ICI treatment. This review explores the complex inter-relations between the gut microbiome, diet and patient nutritional status and the correlations with response to ICI treatment. Different multivariate approaches, including archetypal analysis, are discussed to help identify the combinations of features which may select patients most likely to respond to ICI treatment.

Primary and acquired resistance to first-line therapy for clear cell renal cell carcinoma

The introduction of first-line combinations had improved the outcomes for metastatic renal cell carcinoma (mRCC) compared to sunitinib. However, some patients either have inherent resistance or develop resistance as a result of the treatment. Depending on the kind of therapy employed, many factors underlie resistance to systemic therapy. Angiogenesis and the tumor immune microenvironment (TIME), nevertheless, are inextricably linked. Although angiogenesis and the manipulation of the tumor microenvironment are linked to hypoxia, which emerges as a hallmark of renal cell carcinoma (RCC) pathogenesis, it is only one of the potential elements involved in the distinctive intra- and inter-tumor heterogeneity of RCC that is still dynamic. We may be able to more correctly predict therapy response and comprehend the mechanisms underlying primary or acquired resistance by integrating tumor genetic and immunological markers. In order to provide tools for patient selection and to generate hypotheses for the development of new strategies to overcome resistance, we reviewed the most recent research on the mechanisms of primary and acquired resistance to immune checkpoint inhibitors (ICIs) and tyrosine kinase inhibitors (TKIs) that target the vascular endothelial growth factor receptor (VEGFR).We can choose patients' treatments and cancer preventive strategies using an evolutionary approach thanks to the few evolutionary trajectories that characterize ccRCC.

Potential Effects of Regulating Intestinal Flora on Immunotherapy for Liver Cancer

The intestinal flora plays an important role in the occurrence and development of liver cancer, affecting the efficacy and side effects of conventional antitumor therapy. Recently, immunotherapy for liver cancer has been a palliative treatment for patients with advanced liver cancer lacking surgical indications. Representative drugs include immune checkpoint inhibitors, regulators, tumor vaccines, and cellular immunotherapies. The effects of immunotherapy on liver cancer vary because of the heterogeneity of the tumors. Intestinal flora can affect the efficacy and side effects of immunotherapy for liver cancer by regulating host immunity. Therefore, applying probiotics, prebiotics, antibiotics, and fecal transplantation to interfere with the intestinal flora is expected to become an important means of assisting immunotherapy for liver cancer. This article reviews publications that discuss the relationship between intestinal flora and immunotherapy for liver cancer and further clarifies the potential relationship between intestinal flora and immunotherapy for liver cancer.

Analysis of prognostic factors affecting immune checkpoint inhibitor therapy in tumor patients exposed to antibiotics

Objective

Meta-analysis was performed to evaluate the prognostic factors in tumor patients treated with immune checkpoint inhibitors (ICIs) under antibiotic exposure.

Method

Literature on the effect of antibiotics on the prognosis of tumor patients receiving ICIs was retrieved from Pubmed, Cochrane Library, EMbase, EBSCO Evidence-Based Medicine Database, China Biomedical Literature Database (CBM), and China National Knowledge Network (CNKI), and relevant influencing factors were extracted. Meta-analysis of efficacy was performed using RevMan 5.4 software.

Results

A total of nine studies for 1,677 patients were included. The meta-analysis results showed that, in terms of progression-free survival, gender (male vs. female), Eastern Cooperative Oncology Group performance status (ECOG PS) (1-2 vs. 0), history of another cancer (yes vs. no), liver metastasis (yes vs. no), antibiotics (within the previous 2 months), PD-L1 (1%-49%), and PD-L1 (≥50%) factors are associated with progression-free survival in patients treated with ICIs under antibiotic exposure. In terms of overall survival, gender (male vs. female), ECOG score (1-2 vs. 0), history of another cancer (yes vs. no), brain metastasis (yes vs. no), liver metastasis (yes vs. no), radiation (within the previous 3 months), antibiotics (within the previous 2 months), PD-L1 (1%-49%), and PD-L1 (≥50%) factors are associated with overall survival in patients with antibiotic exposure receiving ICIs for tumor treatment.

Conclusion

Gender, ECOG score, history of another cancer, brain metastasis, liver metastasis, radiation (within the previous 3 months), antibiotics (within the previous 2 months), PD-L1 (1%-49%), and PD-L1 (≥50%) were associated with clinical benefit in patients with antibiotic exposure receiving ICIs for tumor treatment. Based on the above-mentioned factors, clinicians can screen cancer patients who receive ICIs under antibiotic exposure and rationally use antibiotics and ICIs in combination.

Microbiome alteration via fecal microbiota transplantation is effective for refractory immune checkpoint inhibitor-induced colitis

Immune checkpoint inhibitors (ICIs) target advanced malignancies with high efficacy but also predispose patients to immune-related adverse events like immune-mediated colitis (IMC). Given the association between gut bacteria with response to ICI therapy and subsequent IMC, fecal microbiota transplantation (FMT) represents a feasible way to manipulate microbial composition in patients, with a potential benefit for IMC. Here, we present a large case series of 12 patients with refractory IMC who underwent FMT from healthy donors as salvage therapy. All 12 patients had grade 3 or 4 ICI-related diarrhea or colitis that failed to respond to standard first-line (corticosteroids) and second-line immunosuppression (infliximab or vedolizumab). Ten patients (83%) achieved symptom improvement after FMT, and three patients (25%) required repeat FMT, two of whom had no subsequent response. At the end of the study, 92% achieved IMC clinical remission. 16S rRNA sequencing of patient stool samples revealed that compositional differences between FMT donors and patients with IMC before FMT were associated with a complete response after FMT. Comparison of pre- and post-FMT stool samples in patients with complete responses showed significant increases in alpha diversity and increases in the abundances of Collinsella and Bifidobacterium, which were depleted in FMT responders before FMT. Histologically evaluable complete response patients also had decreases in select immune cells , including CD8+ T cells, in the colon after FMT when compared with non-complete response patients (n = 4). This study validates FMT as an effective treatment strategy for IMC and gives insights into the microbial signatures that may play a critical role in FMT response.

The human and animals' malignant melanoma: comparative tumor models and the role of microbiome in dogs and humans

Currently, the most progressively occurring incident cancer is melanoma. The mouse is the most popular model in human melanoma research given its various benefits as a laboratory animal. Nevertheless, unlike humans, mice do not develop melanoma spontaneously, so they need to be genetically manipulated. In opposition, there are several reports of other animals, ranging from wild to domesticated animals, that spontaneously develop melanoma and that have cancer pathways that are similar to those of humans. The influence of the gut microbiome on health and disease is being the aim of many recent studies. It has been proven that the microbiome is a determinant of the host's immune status and disease prevention. In human medicine, there is increasing evidence that changes in the microbiome influences malignant melanoma progression and response to therapy. There are several similarities between some animals and human melanoma, especially between canine and human oral malignant melanoma as well as between the gut microbiome of both species. However, microbiome studies are scarce in veterinary medicine, especially in the oncology field. Future studies need to address the relevance of gut and tissue microbiome for canine malignant melanoma development, which results will certainly benefit both species in the context of translational medicine.

The Impact of Gut Microbiota-Derived Metabolites on the Tumor Immune Microenvironment

Prevention of the effectiveness of anti-tumor immune responses is one of the canonical cancer hallmarks. The competition for crucial nutrients within the tumor microenvironment (TME) between cancer cells and immune cells creates a complex interplay characterized by metabolic deprivation. Extensive efforts have recently been made to understand better the dynamic interactions between cancer cells and surrounding immune cells. Paradoxically, both cancer cells and activated T cells are metabolically dependent on glycolysis, even in the presence of oxygen, a metabolic process known as the Warburg effect. The intestinal microbial community delivers various types of small molecules that can potentially augment the functional capabilities of the host immune system. Currently, several studies are trying to explore the complex functional relationship between the metabolites secreted by the human microbiome and anti-tumor immunity. Recently, it has been shown that a diverse array of commensal bacteria synthetizes bioactive molecules that enhance the efficacy of cancer immunotherapy, including immune checkpoint inhibitor (ICI) treatment and adoptive cell therapy with chimeric antigen receptor (CAR) T cells. In this review, we highlight the importance of commensal bacteria, particularly of the gut microbiota-derived metabolites that are capable of shaping metabolic, transcriptional and epigenetic processes within the TME in a therapeutically meaningful way.

The Gut Microbiome and Pancreatic Cancer Development and Treatment

ABSTRACT

Changes in the gut microbiome have been increasingly shown to accompany oncogenesis across various tumors. Similarly, microbial dysbiosis was found to be associated with pancreatic cancer progression and survival outcomes, expanding the field of tumor microenvironment research in pancreatic cancer. Mechanistic studies in pancreatic cancer models implicate components of the gut and pancreatic cancer microbiome in regulating tumorigenesis by altering cancer cell signaling, modulating immune function, and influencing the efficacy of current therapies in pancreatic cancer. This review discusses the outcomes of microbial modulation across various preclinical and clinical studies and highlights ongoing trials targeting the microbiome for pancreatic cancer therapy.

Evolved bacterial resistance to the chemotherapy gemcitabine modulates its efficacy in co-cultured cancer cells

Drug metabolism by the microbiome can influence anticancer treatment success. We previously suggested that chemotherapies with antimicrobial activity can select for adaptations in bacterial drug metabolism that can inadvertently influence the host's chemoresistance. We demonstrated that evolved resistance against fluoropyrimidine chemotherapy lowered its efficacy in worms feeding on drug-evolved bacteria (Rosener et al., 2020). Here, we examine a model system that captures local interactions that can occur in the tumor microenvironment. Gammaproteobacteria-colonizing pancreatic tumors can degrade the nucleoside-analog chemotherapy gemcitabine and, in doing so, can increase the tumor's chemoresistance. Using a genetic screen in Escherichia coli, we mapped all loss-of-function mutations conferring gemcitabine resistance. Surprisingly, we infer that one third of top resistance mutations increase or decrease bacterial drug breakdown and therefore can either lower or raise the gemcitabine load in the local environment. Experiments in three E. coli strains revealed that evolved adaptation converged to inactivation of the nucleoside permease NupC, an adaptation that increased the drug burden on co-cultured cancer cells. The two studies provide complementary insights on the potential impact of microbiome adaptation to chemotherapy by showing that bacteria-drug interactions can have local and systemic influence on drug activity.

Mechanisms of resistance to immune checkpoint inhibitors in melanoma: What we have to overcome?

Marching into the second decade after the approval of ipilimumab, it is clear that immune checkpoint inhibitors (ICIs) have dramatically improved the prognosis of melanoma. Although the current edge is already high, with a 4-year OS% of 77.9% for adjuvant nivolumab and a 6.5-year OS% of 49% for nivolumab/ipilimumab combination in the metastatic setting, a high proportion of patients with advanced melanoma have no benefit from immunotherapy, or experience an early disease relapse/progression in the first few months of treatment, surviving much less. Reasonably, the primary and acquired resistance to ICIs has entered into the focus of clinical research with positive (e.g., nivolumab and relatlimab combination) and negative feedbacks (e.g., nivolumab with pegylated-IL2, pembrolizumab with T-VEC, nivolumab with epacadostat, and combinatorial triplets of BRAF/MEK inhibitors with immunotherapy). Many intrinsic (intracellular or intra-tumoral) but also extrinsic (systematic) events are considered to be involved in the development of this resistance to ICIs: i) melanoma cell immunogenicity (e.g., tumor mutational burden, antigen-processing machinery and immunogenic cell death, neoantigen affinity and heterogeneity, genomic instability, melanoma dedifferentiation and phenotypic plasticity), ii) immune cell trafficking, T-cell priming, and cell death evasion, iii) melanoma neovascularization, cellular TME components(e.g., T_regs, CAFs) and extracellular matrix modulation, iv) metabolic antagonism in the TME(highly glycolytic status, upregulated CD39/CD73/adenosine pathway, iDO-dependent tryptophan catabolism), v) T-cell exhaustion and negative immune checkpoints, and vi) gut microbiota. In the present overview, we discuss how these parameters compromise the efficacy of ICIs, with an emphasis on the lessons learned by the latest melanoma studies; and in parallel, we describe the main ongoing approaches to overcome the resistance to immunotherapy. Summarizing this information will improve the understanding of how these complicated dynamics contribute to immune escape and will help to develop more effective strategies on how anti-tumor immunity can surpass existing barriers of ICI-refractory melanoma.

Antibiotic Treatment is an Independent Poor Risk Factor in NSCLC But Not in Melanoma Patients Who had Received Anti-PD-1/L1 Monotherapy

BACKGROUND

Antibiotic treatment may reduce the efficacy of cancer immunotherapy by disrupting gut microbiome. We aimed to study the association of antibiotics and survival outcomes in advanced cutaneous melanoma and non-small-cell lung cancer (NSCLC) patients who had received anti-PD-1/L1 monotherapy.

PATIENTS AND METHODS

A total of 222 melanoma and 199 NSCLC patients had received anti-PD-1/L1 monotherapy in 5 Finnish hospitals between January 2014 and December 2020. Clinical characteristics, antibiotic and corticosteroid treatment, and survival outcomes were retrospectively collected from hospital and national medical records.

RESULTS

There were 32% of melanoma and 31% of NSCLC patients who had received antibiotic treatment (ABT) 3 months before to 1 month after the first anti-PD-1/L1 antibody infusion. In survival analyses, early antibiotic treatment was associated with inferior overall survival (OS) (ABT 19.2 [17.6-43.7] vs. no ABT 35.6 [29.3-NA] months, P = .033) but not with inferior progression-free survival (PFS) (ABT 5.8 [3.0-12.6] vs. no ABT 10.2 [7.7-15.3] months, P = .3) in melanoma patients and with inferior OS (ABT 8.6 [6.4-12.3] vs. no ABT 18.5 [15.1-21.6] months, P < .001) and PFS (ABT 2.8 [2.1-4.5] vs. no ABT 5.6 [4.4-8.0] months, P = .0081) in NSCLC patients. In multivariable analyses, ABT was not an independent risk-factor for inferior OS and PFS in melanoma but was associated with inferior OS (hazard ratio [HR] 2.12 [1.37-3.28]) and PFS (HR 1.65 [1.10-2.47]) in NSCLC after adjusted for other risk factors.

CONCLUSIONS

Early ABT was an independent poor risk factor in NSCLC patients who had received anti-PD-1/L1 monotherapy but not in melanoma patients. The weight of ABT as a poor risk factor might depend on other prognostic factors in different cancers.

Shaping the Future of Immunotherapy Targets and Biomarkers in Melanoma and Non-Melanoma Cutaneous Cancers

Recent advances in treating cutaneous melanoma have resulted in impressive patient survival gains. Refinement of disease staging and accurate patient risk classification have significantly improved our prognostic knowledge and ability to accurately stratify treatment. Undoubtedly, the most important step towards optimizing patient outcomes has been the advent of cancer immunotherapy, in the form of immune checkpoint inhibition (ICI). Immunotherapy has established its cardinal role in the management of both early and late-stage melanoma. Through leveraging outcomes in melanoma, immunotherapy has also extended its benefit to other types of skin cancers. In this review, we endeavor to summarize the current role of immunotherapy in melanoma and non-melanoma skin cancers, highlight the most pertinent immunotherapy-related molecular biomarkers, and lastly, shed light on future research directions.

Intratumoral bacteria are an important "accomplice" in tumor development and metastasis

As emerging tumor components, intratumoral bacteria have been found in many solid tumors. Several studies have demonstrated that different cancer subtypes have distinct microbial compositions, and mechanistic studies have shown that intratumoral bacteria may promote cancer initiation and progression through DNA damage, epigenetic modification, inflammatory responses, modulation of host immunity and activation of oncogenes or oncogenic pathways. Moreover, intratumoral bacteria have been shown to modulate tumor metastasis and chemotherapy response. A better understanding of the tumor microenvironment and its associated microbiota will facilitate the design of new metabolically engineered species, opening up a new era of intratumoral bacteria-based cancer therapy. However, many questions remain to be resolved, such as where intratumoral bacteria originate and whether there is a direct causal relationship between intratumoral bacteria and tumor susceptibility. In addition, suitable preclinical models and more advanced detection techniques are crucial for studying the biological functions of intratumoral bacteria. In this review, we summarize the complicated role of intratumoral bacteria in the regulation of cancer development and metastasis and discuss their carcinogenic mechanisms and potential therapeutic aspects.

A systematic review and meta-analysis evaluating the impact of antibiotic use on the clinical outcomes of cancer patients treated with immune checkpoint inhibitors

Background

Immune checkpoint inhibitors (ICIs) have considerably improved patient outcomes in various cancer types, but their efficacy remains poorly predictable among patients. The intestinal microbiome, whose balance and composition can be significantly altered by antibiotic use, has recently emerged as a factor that may modulate ICI efficacy. The objective of this systematic review and meta-analysis is to investigate the impact of antibiotics on the clinical outcomes of cancer patients treated with ICIs.

Methods

PubMed and major oncology conference proceedings were systematically searched to identify all studies reporting associations between antibiotic use and at least one of the following endpoints: Overall Survival (OS), Progression-Free Survival (PFS), Objective Response Rate (ORR) and Progressive Disease (PD) Rate. Pooled Hazard Ratios (HRs) for OS and PFS, and pooled Odds Ratios (ORs) for ORR and PD were calculated. Subgroup analyses on survival outcomes were also performed to investigate the potential differential effect of antibiotics according to cancer types and antibiotic exposure time windows.

Results

107 articles reporting data for 123 independent cohorts were included, representing a total of 41,663 patients among whom 11,785 (28%) received antibiotics around ICI initiation. The pooled HRs for OS and PFS were respectively of 1.61 [95% Confidence Interval (CI) 1.48-1.76] and 1.45 [95% CI 1.32-1.60], confirming that antibiotic use was significantly associated with shorter survival. This negative association was observed consistently across all cancer types for OS and depending on the cancer type for PFS. The loss of survival was particularly strong when antibiotics were received shortly before or after ICI initiation. The pooled ORs for ORR and PD were respectively of 0.59 [95% CI 0.47-0.76] and 1.86 [95% CI 1.41-2.46], suggesting that antibiotic use was significantly associated with worse treatment-related outcomes.

Conclusion

As it is not ethically feasible to conduct interventional, randomized, controlled trials in which antibiotics would be administered to cancer patients treated with ICIs to demonstrate their deleterious impact versus control, prospective observational studies and interventional trials involving microbiome modifiers are crucially needed to uncover the role of microbiome and improve patient outcomes. Such studies will reduce the existing publication bias by allowing analyses on more homogeneous populations, especially in terms of treatments received, which is not possible at this stage given the current state of the field. In the meantime, antibiotic prescription should be cautiously considered in cancer patients receiving ICIs.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42019145675.

Antibiotic Prescriptions in Lung Cancer and Melanoma Populations: Differences With Potential Clinical Implications in the Immunotherapy Era

INTRODUCTION

Antibiotic exposure is associated with worse clinical outcomes in patients receiving immune checkpoint inhibitors (ICI). We analyzed antibiotic prescription patterns in lung cancer and melanoma, two malignancies in which ICI are used broadly across stages.

METHODS

We performed a retrospective cohort study of adults in the U.S. Veterans Affairs (VA) medical system diagnosed with lung cancer or melanoma from 2003 to 2016. We defined antibiotic exposure as receipt of a prescription for a systemic antibacterial agent between 6 months before and 6 months after cancer diagnosis. Demographics, clinical variables, prescriptions, and diagnostic codes were abstracted from the VA Corporate Data Warehouse. Antibiotic exposure was compared using t tests, Chi-square, and multivariate analyses.

RESULTS

A total of 310,321 patients (280,068 lung cancer, 30,253 melanoma) were included in the analysis. Antibiotic exposure was more common among patients with lung cancer (42% vs. 24% for melanoma; P < .001). Among antibiotic-exposed patients, those with lung cancer were more likely to receive prescriptions for multiple antibiotics (47% vs. 30% for melanoma; P < .001). In multivariate analyses, antibiotic exposure was associated with lung cancer diagnosis (HR 1.50; 95% CI, 1.46-1.55), comorbidity score (HR 1.08; 95% CI, 1.08-1.09), non-white race (HR 1.11; 95% CI, 1.06-1.17), and female gender (HR 1.31; 95% CI, 1.24-1.37).

CONCLUSION

Among cancer patients, antibiotics are prescribed frequently. Antibiotic exposure is more common in certain cancer types and patient populations. Given the negative effect antibiotic exposure has on immunotherapy outcomes, these observations may have clinical and healthy policy implications.

Current landscape and tailored management of immune-related adverse events

Unprecedented advances have been made in immune checkpoint inhibitors (ICIs) in the treatment of cancer. However, the overall benefits from ICIs are impaired by the increasing incidence of immune-related adverse events (irAEs). Although several factors and mechanisms have been proposed in the development of irAEs, there is still incomprehensive understanding of irAEs. Therefore, it is urgent to identify certain risk factors and biomarkers that predict the development of irAEs, as well as to understand the underlying mechanisms of these adverse events. Herein, we comprehensively summarize the state-of-the-art knowledge about clinical features and the related risk factors of irAEs. Particularly, we also discuss relevant mechanisms of irAEs and address the mechanism-based strategies, aiming to develop a tailored management approach for irAEs.

The Association between Baseline Proton Pump Inhibitors, Immune Checkpoint Inhibitors, and Chemotherapy: A Systematic Review with Network Meta-Analysis

(1) Although emerging evidence suggests that proton pump inhibitor (PPI)-induced dysbiosis negatively alters treatment response to immune checkpoint inhibitors (ICIs) in cancer patients, no study systematically investigates the association between PPIs, ICIs, and chemotherapy; (2) Cochrane Library, Embase, Medline, and PubMed were searched from inception to 20 May 2022, to identify relevant studies involving patients receiving ICIs or chemotherapy and reporting survival outcome between PPI users and non-users. Survival outcomes included overall survival (OS) and progression-free survival (PFS). Network meta-analyses were performed using random-effects models. p-scores, with a value between 0 and 1, were calculated to quantify the treatment ranking, with a higher score suggesting a higher probability of greater effectiveness. We also conducted pairwise meta-analyses of observational studies to complement our network meta-analysis; (3) We identified 62 studies involving 26,484 patients (PPI = 8834; non-PPI = 17,650), including non-small cell lung cancer (NSCLC), urothelial carcinoma (UC), melanoma, renal cell carcinoma (RCC), hepatocellular carcinoma (HCC), and squamous cell carcinoma (SCC) of the neck and head. Eight post-hoc analyses from 18 randomized-controlled trials were included in our network, which demonstrated that, in advanced NSCLC and UC, patients under ICI treatment with concomitant PPI (p-score: 0.2016) are associated with both poorer OS (HR, 1.49; 95% CI, 1.37 to 1.67) and poorer PFS (HR, 1.41; 95% CI, 1.25 to 1.61) than those without PPIs (p-score: 1.000). Patients under ICI treatment with concomitant PPI also had poorer OS (HR, 1.18; 95% CI, 1.07 to 1.31) and poorer PFS (HR, 1.30; 95% CI, 1.14 to 1.48) in comparison with those receiving chemotherapy (p-score: 0.6664), implying that PPIs may compromise ICI's effectiveness, making it less effective than chemotherapy. Our pairwise meta-analyses also supported this association. Conversely, PPI has little effect on patients with advanced melanoma, RCC, HCC, and SCC of the neck and head who were treated with ICIs; (4) "PPI-induced dysbiosis" serves as a significant modifier of treatment response in both advanced NSCLC and UC that are treated with ICIs, compromising the effectiveness of ICIs to be less than that of chemotherapy. Thus, clinicians should avoid unnecessary PPI prescription in these patients. "PPI-induced dysbiosis", on the other hand, does not alter the treatment response to ICIs in advanced melanoma, RCC, HCC, and SCC of the head and neck.

Conversion of unresponsiveness to immune checkpoint inhibition by fecal microbiota transplantation in patients with metastatic melanoma: study protocol for a randomized phase Ib/IIa trial

BACKGROUND

The gut microbiome plays an important role in immune modulation. Specifically, presence or absence of certain gut bacterial taxa has been associated with better antitumor immune responses. Furthermore, in trials using fecal microbiota transplantation (FMT) to treat melanoma patients unresponsive to immune checkpoint inhibitors (ICI), complete responses (CR), partial responses (PR), and durable stable disease (SD) have been observed. However, the underlying mechanism determining which patients will or will not respond and what the optimal FMT composition is, has not been fully elucidated, and a discrepancy in microbial taxa associated with clinical response has been observed between studies. Furthermore, it is unknown whether a change in the microbiome itself, irrespective of its origin, or FMT from ICI responding donors, is required for reversion of ICI-unresponsiveness. To address this, we will transfer microbiota of either ICI responder or nonresponder metastatic melanoma patients via FMT.

METHODS

In this randomized, double-blinded phase Ib/IIa trial, 24 anti-PD1-refractory patients with advanced stage cutaneous melanoma will receive an FMT from either an ICI responding or nonresponding donor, while continuing anti-PD-1 treatment. Donors will be selected from patients with metastatic melanoma treated with anti-PD-1 therapy. Two patients with a good response (≥ 30% decrease according to RECIST 1.1 within the past 24 months) and two patients with progression (≥ 20% increase according to RECIST 1.1 within the past 3 months) will be selected as ICI responding or nonresponding donors, respectively. The primary endpoint is clinical benefit (SD, PR or CR) at 12 weeks, confirmed on a CT scan at 16 weeks. The secondary endpoint is safety, defined as the occurrence of grade ≥ 3 toxicity. Exploratory endpoints are progression-free survival and changes in the gut microbiome, metabolome, and immune cells.

DISCUSSION

Transplanting fecal microbiota to restore the patients' perturbed microbiome has proven successful in several indications. However, less is known about the potential role of FMT to improve antitumor immune response. In this trial, we aim to investigate whether administration of FMT can reverse resistance to anti-PD-1 treatment in patients with advanced stage melanoma, and whether the ICI-responsiveness of the feces donor is associated with its effectiveness.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT05251389 (registered 22-Feb-2022). Protocol V4.0 (08-02-2022).

Programmed Cell Death-Ligand 1 in Head and Neck Squamous Cell Carcinoma: Molecular Insights, Preclinical and Clinical Data, and Therapies

Aberrant expression of the programmed cell death protein ligand 1 (PD-L1) constitutes one of the main immune evasion mechanisms of cancer cells. The approval of drugs against the PD-1-PD-L1 axis has given new impetus to the chemo-therapy of many malignancies. We performed a literature review from 1992 to August 2022, summarizing evidence regarding molecular structures, physiological and pathological roles, mechanisms of PD-L1 overexpression, and immunotherapy evasion. Furthermore, we summarized the studies concerning head and neck squamous cell carcinomas (HNSCC) immunotherapy and the prospects for improving the associated outcomes, such as identifying treatment response biomarkers, new pharmacological combinations, and new molecules. PD-L1 overexpression can occur via four mechanisms: genetic modifications; inflammatory signaling; oncogenic pathways; microRNA or protein-level regulation. Four molecular mechanisms of resistance to immunotherapy have been identified: tumor cell adaptation; changes in T-cell function or proliferation; alterations of the tumor microenvironment; alternative immunological checkpoints. Immunotherapy was indeed shown to be superior to traditional chemotherapy in locally advanced/recurrent/metastatic HNSCC treatments.

The negative effect of antibiotics on RCC patients with immunotherapy: A systematic review and meta-analysis

Background

Microbiome dysbiosis is considered a predictive biomarker of clinical response in renal cell carcinoma (RCC), which can be regulated by antibiotics (ATB). Multiple studies have shown that concomitant ATB administration has inhibitory effects on immunotherapy in RCC. This review aimed to assess the impact of ATB on patient survival and tumor response in RCC with immunotherapy.

Methods

Literature evaluating the effect of ATB on immunotherapy in RCC from Cochrane Library^®, PubMed^®, Embase^®, Scopus^®, and Web of Science^® were systematically searched. Hazard ratios (HR) for progression-free survival (PFS) and overall survival (OS), odds ratio (OR) for objective response rate (ORR) and primary progressive disease (PD) were pooled as effect sizes for clinical outcomes. Subgroup analysis was conducted to reveal the determinants of the effect of ATB on immunotherapy, including time windows of ATB exposure to immunotherapy initiation, ICIs treatment and study location. The leave-one-out approach was adopted to analyze the heterogeneity formulated. Cumulative meta-analysis adding by time was used to observe dynamic changes of the results.

Results

Ten studies were included in the systematic review and six studies (with n=1,104 patients) were included in the meta-analysis, four studies were excluded for overlapping patients with subsequent larger studies and lack of unique patient-level data. ATB administration was significantly correlated with shorter PFS (HR=2.10, 95%CI [1.54; 2.85], I² = 2% after omitting study Derosa et al, 2021 detected by leave-one-out approach), shorter OS (HR=1.69, 95%CI [1.34; 2.12], I² = 25%) and worse ORR (OR=0.58, 95%CI [0.41; 0.84]), but no difference was observed in risk of PD (OR=1.18, 95%CI [0.97; 1.44]). No significant differences existed among the subgroups for determining the determinants of ATB inhibition.

Conclusions

Concomitant ATB with immunotherapy was associated with worse PFS, OS and ORR in RCC. No publication bias was observed in this study.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=349577, identifier CRD42022349577.

The Role of the Microbiome in Pancreatic Cancer

Simple Summary

Pancreatic cancer is deadly cancer characterized by dense stroma creating an immunosuppressive tumor microenvironment. Accumulating evidences indicate that the microbiome plays an important role in pancreatic cancer development and progression via the local and systemic inflammation and immune responses. The alteration of the microbiome modulates the tumor microenvironment and immune system in pancreatic cancer, which affects the efficacy of chemotherapies including immune-targeted therapies. Understanding the role of microbiome and underlying mechanisms may lead to novel biomarkers and therapeutic strategies for pancreatic cancer. This review summarizes the current evidence on the role of the microbiome in pancreatic cancer.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, with little improvement in outcomes in recent decades, although the molecular and phenotypic characterization of PDAC has contributed to advances in tailored therapies. PDAC is characterized by dense stroma surrounding tumor cells, which limits the efficacy of treatment due to the creation of a physical barrier and immunosuppressive environment. Emerging evidence regarding the microbiome in PDAC implies its potential role in the initiation and progression of PDAC. However, the underlying mechanisms of how the microbiome affects the local tumor microenvironment (TME) as well as the systemic immune system have not been elucidated in PDAC. In addition, therapeutic strategies based on the microbiome have not been established. In this review, we summarize the current evidence regarding the role of the microbiome in the development of PDAC and discuss a possible role for the microbiome in the early detection of PDAC in relation to premalignant pancreatic diseases, such as chronic pancreatitis and intraductal papillary mucinous neoplasm (IPMN). In addition, we discuss the potential role of the microbiome in the treatment of PDAC, especially in immunotherapy, although the biomarkers used to predict the efficacy of immunotherapy in PDAC are still unknown. A comprehensive understanding of tumor-associated immune responses, including those involving the microbiome, holds promise for new treatments in PDAC.