Reactive Neutrophil Responses Dependent on the Receptor Tyrosine Kinase c-MET Limit Cancer Immunotherapy

Metabolic reprogramming of neutrophils in the tumor microenvironment: Emerging therapeutic targets

Neutrophils are pivotal in the immune system and have been recognized as significant contributors to cancer development and progression. These cells undergo metabolic reprogramming in response to various stimulus, including infections, diseases, and the tumor microenvironment (TME). Under normal conditions, neutrophils primarily rely on aerobic glucose metabolism for energy production. However, within the TME featured by hypoxic and nutrient-deprived conditions, they shift to altered anaerobic glycolysis, lipid metabolism, mitochondrial metabolism and amino acid metabolism to perform their immunosuppressive functions and facilitate tumor progression. Targeting neutrophils within the TME is a promising therapeutic approach. Yet, focusing on their metabolic pathways presents a novel strategy to enhance cancer immunotherapy. This review synthesizes the current understanding of neutrophil metabolic reprogramming in the TME, with an emphasis on the underlying molecular mechanisms and signaling pathways. Studying neutrophil metabolism in the TME poses challenges, such as their short lifespan and the metabolic complexity of the environment, necessitating the development of advanced research methodologies. This review also discusses emerging solutions to these challenges. In conclusion, given their integral role in the TME, targeting the metabolic pathways of neutrophils could offer a promising avenue for cancer therapy.

Targeting HGF/c-MET signaling to regulate the tumor microenvironment: Implications for counteracting tumor immune evasion

The hepatocyte growth factor (HGF) along with its receptor (c-MET) are crucial in preserving standard cellular physiological activities, and imbalances in the c-MET signaling pathway can lead to the development and advancement of tumors. It has been extensively demonstrated that immune checkpoint inhibitors (ICIs) can result in prolonged remission in certain patients. Nevertheless, numerous preclinical studies have shown that MET imbalance hinders the effectiveness of anti-PD-1/PD-L1 treatments through various mechanisms. Consequently, clarifying the link between the c-MET signaling pathway and the tumor microenvironment (TME), as well as uncovering the effects of anti-MET treatment on ICI therapy, is crucial for enhancing the outlook for tumor patients. In this review, we examine the impact of abnormal activation of the HGF/c-MET signaling pathway on the control of the TME and the processes governing PD-L1 expression in cancer cells. The review thoroughly examines both clinical and practical evidence regarding the use of c-MET inhibitors alongside PD-1/PD-L1 inhibitors, emphasizing that focusing on c-MET with immunotherapy enhances the effectiveness of treating MET tumors exhibiting elevated PD-L1 expression.

Neutrophil extracellular traps in tumor metabolism and microenvironment

Neutrophil extracellular traps (NETs) are intricate, web-like formations composed of DNA, histones, and antimicrobial proteins, released by neutrophils. These structures participate in a wide array of physiological and pathological activities, including immune rheumatic diseases and damage to target organs. Recently, the connection between NETs and cancer has garnered significant attention. Within the tumor microenvironment and metabolism, NETs exhibit multifaceted roles, such as promoting the proliferation and migration of tumor cells, influencing redox balance, triggering angiogenesis, and driving metabolic reprogramming. This review offers a comprehensive analysis of the link between NETs and tumor metabolism, emphasizing areas that remain underexplored. These include the interaction of NETs with tumor mitochondria, their effect on redox states within tumors, their involvement in metabolic reprogramming, and their contribution to angiogenesis in tumors. Such insights lay a theoretical foundation for a deeper understanding of the role of NETs in cancer development. Moreover, the review also delves into potential therapeutic strategies that target NETs and suggests future research directions, offering new perspectives on the treatment of cancer and other related diseases.

Myeloid effector cells in cancer

The role of myeloid cells in tumor immunity is multifaceted. While dendritic cells support T cell-mediated tumor control, the highly heterogenous populations of macrophages, neutrophils, and immature myeloid cells were generally considered immunosuppressive. This view has led to effective therapies reinvigorating tumor-reactive T cells; however, targeting the immunosuppressive effects of macrophages and neutrophils to boost the cancer immunity cycle was clinically less successful. Recent studies interrogating the role of immune cells in the context of successful immunotherapy affirm the key role of T cells, but simultaneously challenge the idea that the cytotoxic function of T cells is the main contributor to therapy-driven tumor regression. Rather, therapy-activated intra-tumoral T cells recruit and activate or reprogram several myeloid effector cell types, the presence of which is necessary for tumor rejection. Here, we reappreciate the key role of myeloid effector cells in tumor rejection as this may help to shape future successful immunotherapies.

Neutrophil diversity and function in health and disease

Neutrophils, the most abundant type of granulocyte, are widely recognized as one of the pivotal contributors to the acute inflammatory response. Initially, neutrophils were considered the mobile infantry of the innate immune system, tasked with the immediate response to invading pathogens. However, recent studies have demonstrated that neutrophils are versatile cells, capable of regulating various biological processes and impacting both human health and disease. Cytokines and other active mediators regulate the functional activity of neutrophils by activating multiple receptors on these cells, thereby initiating downstream signal transduction pathways. Dysfunctions in neutrophils and disruptions in neutrophil homeostasis have been implicated in the pathogenesis of numerous diseases, including cancer and inflammatory disorders, often due to aberrant intracellular signaling. This review provides a comprehensive synthesis of neutrophil biological functions, integrating recent advancements in this field. Moreover, it examines the biological roles of receptors on neutrophils and downstream signaling pathways involved in the regulation of neutrophil activity. The pathophysiology of neutrophils in numerous human diseases and emerging therapeutic approaches targeting them are also elaborated. This review also addresses the current limitations within the field of neutrophil research, highlighting critical gaps in knowledge that warrant further investigation. In summary, this review seeks to establish a comprehensive and multidimensional model of neutrophil regulation, providing new perspectives for potential clinical applications and further research.

c-MET and the immunological landscape of cancer: novel therapeutic strategies for enhanced anti-tumor immunity

Cellular mesenchymal-epithelial transition factor (c-MET), also known as hepatocyte growth factor receptor (HGFR), is a crucial receptor tyrosine kinase implicated in various solid tumors, including lung, breast, and liver cancers. The concomitant expression of c-MET and PD-L1 in tumors, such as hepatocellular carcinoma, highlights their prognostic significance and connection to therapeutic resistance. Cancer-associated fibroblasts and mesenchymal stromal cells produce hepatocyte growth factor (HGF), activating c-MET signaling in tumor cells and myeloid-derived suppressor cells (MDSC). This activation leads to metabolic reprogramming and increased activity of enzymes like glutaminase (GLS), indoleamine 2,3-dioxygenase (IDO), and arginase 1 (ARG1), depleting essential amino acids in the tumor microenvironment that are vital for effector immune cell function. This review highlights the interplay between tumor cells and myeloid-derived suppressor cells (MDSCs) that create an immunosuppressive environment while providing targets for c-MET-focused immunotherapy. It emphasizes the clinical implications of c-MET inhibition on the behavior of immune cells such as neutrophils, macrophages, T cells, and NK cells. It explores the potential of c-MET antagonism combined with immunotherapeutic strategies to enhance cancer treatment paradigms. This review also discusses the innovative cancer immunotherapies targeting c-MET, including chimeric antigen receptor (CAR) therapies, monoclonal antibodies, and antibody-drug conjugates, while encouraging the development of a comprehensive strategy that simultaneously tackles immune evasion and enhances anti-tumor efficacy further to improve the clinical prognoses for patients with c-MET-positive malignancies. Despite the challenges and variability in efficacy across different cancer subtypes, continued research into the molecular mechanisms and the development of innovative therapeutic strategies will be crucial.

Type I MET inhibitors cooperate with PD-1 blockade to promote rejection of hepatocellular carcinoma

Blockade of the immune checkpoints programmed death-1 (PD-1) and cytotoxic lymphocyte antigen 4 has improved outcomes for patients with hepatocellular carcinoma (HCC), yet most still fail to achieve objective clinical benefit. MET plays key roles in both HCC tumorigenesis and immunosuppressive conditioning; however, inhibition of MET causes upregulation of PD-ligand 1 (PD-L1) suggesting the use of these inhibitors in the context of PD-1 blockade. We sought to investigate across the Hepa1-6, HCA-1 and diethylnitrosamine (DEN) models of HCC whether the combination of more specific type I versus more pleiotropic type II MET inhibitors would confer superior outcomes in combination with PD-1 blockade. While MET inhibition demonstrated cooperativity with αPD-1 across all three models, the type I MET inhibitor capmatinib showed optimal activity in combination and statistically significantly outperformed the combination with the type II inhibitor cabozantinib in the αPD-1 refractory DEN model. In both HCA-1 and DEN HCC, the capmatinib and αPD-1 combination enhanced CD8 T cell frequency and activation state while limiting intratumoral myeloid immune suppression. In vitro studies of antigen-specific T cell activation reveal significantly less inhibition of effector cytokine production and proliferation by capmatinib versus by type II or type III MET inhibitors. These findings suggest significant potential for clinical HCC combination studies of type I MET inhibitors and PD-1 blockade where prior trials using type II inhibitors have yielded limited benefit.

Targeting the MET gene: unveiling therapeutic opportunities in immunotherapy within the tumor immune microenvironment of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) represents the most prevalent histological subtype of lung cancer. Within this disease, the MET gene emerges as a critical therapeutic target, exhibiting various forms of dysregulation. Although MET tyrosine kinase inhibitors, HGF/c-MET targeting antibodies, and antibody-drug conjugates constitute the primary treatment modalities for patients with MET-altered NSCLC, numerous questions remain regarding their optimal application. The advent of immunotherapy holds promise for enhancing therapeutic outcomes in patients with MET-altered NSCLC. MET mutations can reshape the tumor immune microenvironment of NSCLC by reducing tumor immunogenicity, inducing exhaustion in immune-activated cells, and promoting immune evasion, which are crucial for modulating treatment responses. Furthermore, we emphasize the promising synergy of immunotherapy with emerging treatments and the challenges and opportunities in refining these approaches to improve patient outcomes.

Neutrophils under the microscope: neutrophil dynamics in infection, inflammation, and cancer revealed using intravital imaging

Neutrophils rapidly respond to inflammation resulting from infection, injury, and cancer. Intravital microscopy (IVM) has significantly advanced our understanding of neutrophil behavior, enabling real-time visualization of their migration, interactions with pathogens, and coordination of immune responses. This review delves into the insights provided by IVM studies on neutrophil dynamics in various inflammatory contexts. We also examine the dual role of neutrophils in tumor microenvironments, where they can either facilitate or hinder cancer progression. Finally, we highlight how computational modeling techniques, especially agent-based modeling, complement experimental data by elucidating neutrophil kinetics at the level of individual cells as well as their collective behavior. Understanding the role of neutrophils in health and disease is essential for developing new strategies for combating infection, inflammation and cancer.

Genomic and Immune Landscape Comparison of MET Exon 14 Skipping and MET-Amplified Non-small Cell Lung Cancer

BACKGROUND

Mutation or amplification of the mesenchymal-epithelial transition (MET) tyrosine kinase receptor causes dysregulation of receptor function and stimulates tumor growth in non-small cell lung cancer (NSCLC) with the most common mutation being MET exon 14 (METex14). We sought to compare the genomic and immune landscape of MET-altered NSCLC with MET wild-type NSCLC.

METHODS

18,047 NSCLC tumors were sequenced with Tempus xT assay. Tumors were categorized based on MET exon 14 (METex14) mutations; low MET amplification defined as a copy number gain (CNG) 6-9, high MET amplification defined as CNG ≥ 10, and MET other type mutations. Immuno-oncology (IO) biomarkers and the frequency of other somatic gene alterations were compared across MET-altered and MET wild-type groups.

RESULTS

276 (1.53%) METex14, 138 (0.76%) high METamp, 63 (0.35%) low METamp, 27 (0.15%) MET other, and 17,543 (97%) MET wild-type were identified. Patients with any MET mutation including METex14 were older, while patients with METex14 were more frequently female and nonsmokers. MET gene expression was highest in METamp tumors. PD-L1 positivity rates were higher in MET-altered groups than MET wild-type. METex14 exhibited the lowest tumor mutational burden (TMB) and lowest neoantigen tumor burden (NTB). METamp exhibited the lowest proportion of CD4 T cells and the highest proportion of NK cells. There were significant differences in co-alterations between METamp and METex14.

CONCLUSIONS

METex14 tumors exhibited differences in IO biomarkers and the somatic landscape compared to non-METex14 NSCLC tumors. Variations in immune profiles can affect immunotherapy selection in MET-altered NSCLC and require further exploration.

Unveiling the Role of HGF/c-Met Signaling in Non-Small Cell Lung Cancer Tumor Microenvironment

Non-small cell lung cancer (NSCLC) is characterized by several molecular alterations that contribute to its development and progression. These alterations include the epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), human epidermal growth factor receptor 2 (HER2), and mesenchymal-epithelial transition factor (c-MET). Among these, the hepatocyte growth factor (HGF)/c-MET signaling pathway plays a crucial role in NSCLC. In spite of this, the involvement of the HGF/c-MET signaling axis in remodeling the tumor microenvironment (TME) remains relatively unexplored. This review explores the biological functions of the HGF/c-MET signaling pathway in both normal and cancerous cells, examining its multifaceted roles in the NSCLC tumor microenvironment, including tumor cell proliferation, migration and invasion, angiogenesis, and immune evasion. Furthermore, we summarize the current progress and clinical applications of MET-targeted therapies in NSCLC and discuss future research directions, such as the development of novel MET inhibitors and the potential of combination immunotherapy.

Liraglutide enhances the effect of checkpoint blockade in lung and liver cancers through the inhibition of neutrophil extracellular traps

Glucagon-like peptide-1 (GLP-1) regulates glycemic excursions by augmenting insulin production and inhibiting glucagon secretion. Liraglutide, a long-acting GLP-1 analog, can improve glycemic control for treating type 2 diabetes and prevent neutrophil extravasation in inflammation. Here, we explored the role of liraglutide in the development and therapy of murine lung and liver cancers. In this study, liraglutide substantially decreased circulating neutrophil extracellular trap (NET) markers myeloperoxidase, elastase, and dsDNA in Lewis lung cancer (LLC) and Hepa1-6 tumor-bearing mice. Furthermore, liraglutide downregulated NETs and reactive oxygen species (ROS) of neutrophils in the tumor microenvironment. Functionally, in vitro experiments showed that liraglutide reduced NET formation by inhibiting ROS. In addition, we showed that liraglutide enhanced the anti-tumoral efficiency of programmed cell death-1 (PD-1) inhibition in LLC and Hepa1-6 tumor-bearing C57BL/6 mice. However, the removal of NETs significantly weakened the antitumor efficiency of liraglutide. We further demonstrated that the long-term antitumor CD8+ T cell responses induced by the combination therapy rejected rechallenges by respective tumor cell lines. Taken together, our findings suggest that liraglutide may promote the anti-tumoral efficiency of PD-1 inhibition by reducing NETs in lung and liver cancers.

Bayesian sequential monitoring strategies for trials of digestive cancer therapeutics

BACKGROUND

New therapeutics in oncology have presented challenges to existing paradigms and trial designs in all phases of drug development. As a motivating example, we considered an ongoing phase II trial planned to evaluate the combination of a MET inhibitor and an anti-PD-L1 immunotherapy to treat advanced oesogastric carcinoma. The objective of the paper was to exemplify the planning of an adaptive phase II trial with novel anti-cancer agents, including prolonged observation windows and joint sequential evaluation of efficacy and toxicity.

METHODS

We considered various candidate designs and computed decision rules assuming correlations between efficacy and toxicity. Simulations were conducted to evaluate the operating characteristics of all designs.

RESULTS

Design approaches allowing continuous accrual, such as the time-to-event Bayesian Optimal Phase II design (TOP), showed good operating characteristics while ensuring a reduced trial duration. All designs were sensitive to the specification of the correlation between efficacy and toxicity during planning, but TOP can take that correlation into account more easily.

CONCLUSIONS

While specifying design working hypotheses requires caution, Bayesian approaches such as the TOP design had desirable operating characteristics and allowed incorporating concomittant information, such as toxicity data from concomitant observations in another relevant patient population (e.g., defined by mutational status).

IL1R2 Blockade Alleviates Immunosuppression and Potentiates Anti-PD-1 Efficacy in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited therapeutic options. IL1 receptor type 2 (IL1R2) promotes breast tumor-initiating cell (BTIC) self-renewal and tumor growth in TNBC, indicating that targeting it could improve patient treatment. In this study, we observed that IL1R2 blockade strongly attenuated macrophage recruitment and the polarization of tumor-associated macrophages (TAM) to inhibit BTIC self-renewal and CD8+ T-cell exhaustion, which resulted in reduced tumor burden and prolonged survival in TNBC mouse models. IL1R2 activation by TAM-derived IL1β increased PD-L1 expression by interacting with the transcription factor Yin Yang 1 (YY1) and inducing YY1 ubiquitination and proteasomal degradation in both TAMs and TNBC cells. Loss of YY1 alleviated the transcriptional repression of c-Fos, which is a transcriptional activator of PDL-1. Combined treatment with an IL1R2-neutralizing antibodies and anti-PD-1 led to enhanced antitumor efficacy and reduced TAMs, BTICs, and exhausted CD8+ T cells. These results suggest that IL1R2 blockade might be a strategy to potentiate immune checkpoint blockade efficacy in TNBC to improve patient outcomes. Significance: IL1R2 in both macrophages and breast cancer cells orchestrates an immunosuppressive tumor microenvironment by upregulating PD-L1 expression and can be targeted to enhance the efficacy of anti-PD-1 in triple-negative breast cancer.

CRKL dictates anti-PD-1 resistance by mediating tumor-associated neutrophil infiltration in hepatocellular carcinoma

BACKGROUND & AIMS

The effectiveness of immune checkpoint inhibitor (ICI) therapy for hepatocellular carcinoma (HCC) is limited by treatment resistance. However, the mechanisms underlying immunotherapy resistance remain elusive. We aimed to identify the role of CT10 regulator of kinase-like (CRKL) in resistance to anti-PD-1 therapy in HCC.

METHODS

Gene expression in HCC specimens from 10 patients receiving anti-PD-1 therapy was identified by RNA-sequencing. A total of 404 HCC samples from tissue microarrays were analyzed by immunohistochemistry. Transgenic mice (Alb-Cre/Trp53fl/fl) received hydrodynamic tail vein injections of a CRKL-overexpressing vector. Mass cytometry by time of flight was used to profile the proportion and status of different immune cell lineages in the mouse tumor tissues.

RESULTS

CRKL was identified as a candidate anti-PD-1-resistance gene using a pooled genetic screen. CRKL overexpression nullifies anti-PD-1 treatment efficacy by mobilizing tumor-associated neutrophils (TANs), which block the infiltration and function of CD8+ T cells. PD-L1+ TANs were found to be an essential subset of TANs that were regulated by CRKL expression and display an immunosuppressive phenotype. Mechanistically, CRKL inhibits APC (adenomatous polyposis coli)-mediated proteasomal degradation of β-catenin by competitively decreasing Axin1 binding, and thus promotes VEGFα and CXCL1 expression. Using human HCC samples, we verified the positive correlations of CRKL/β-catenin/VEGFα and CXCL1. Targeting CRKL using CRISPR-Cas9 gene editing (CRKL knockout) or its downstream regulators effectively restored the efficacy of anti-PD-1 therapy in an orthotopic mouse model and a patient-derived organotypic tumor spheroid model.

CONCLUSIONS

Activation of the CRKL/β-catenin/VEGFα and CXCL1 axis is a critical obstacle to successful anti-PD-1 therapy. Therefore, CRKL inhibitors combined with anti-PD-1 could be useful for the treatment of HCC.

IMPACT AND IMPLICATIONS

Here, we found that CRKL was overexpressed in anti-PD-1-resistant hepatocellular carcinoma (HCC) and that CRKL upregulation promotes anti-PD-1 resistance in HCC. We identified that upregulation of the CRKL/β-catenin/VEGFα and CXCL1 axis contributes to anti-PD-1 tolerance by promoting infiltration of tumor-associated neutrophils. These findings support the strategy of bevacizumab-based immune checkpoint inhibitor combination therapy, and CRKL inhibitors combined with anti-PD-1 therapy may be developed for the treatment of HCC.

Neutrophil migration participates in the side effect of recombinant human tissue plasminogen activator

AIMS

Ischemic stroke remains a challenge in medical research because of the limited treatment options. Recombinant human tissue plasminogen activator (rtPA) is the primary treatment for recanalization. However, nearly 50% of the patients experience complications that result in ineffective reperfusion. The precise factors contributing to ineffective reperfusion remain unclear; however, recent studies have suggested that immune cells, notably neutrophils, may influence the outcome of rtPA thrombolysis via mechanisms such as the formation of neutrophil extracellular traps. This study aimed to explore the nonthrombolytic effects of rtPA on neutrophils and highlight their contribution to ineffective reperfusion.

METHODS

We evaluated the effects of rtPA treatment on middle cerebral artery occlusion in rats. We also assessed neutrophil infiltration and activation after rtPA treatment in vitro and in vivo in a small cohort of patients with massive cerebral ischemia (MCI).

RESULTS

rtPA increased neutrophil infiltration into the brain microvessels and worsened blood-brain barrier damage during ischemia. It also increased the neutrophil counts of the patients with MCI.

CONCLUSION

Neutrophils play a crucial role in promoting ischemic injury and blood-brain barrier disruption, making them potential therapeutic targets.

Deregulated immune cell recruitment orchestrated by c-MET impairs pulmonary inflammation and fibrosis

BACKGROUND

Pulmonary fibrosis (PF) represents the pathologic end stage of several interstitial lung diseases (ILDs) associated with high morbidity and mortality rates. However, current treatments can only delay disease progression rather than provide a cure. The role of inflammation in PF progression is well-established, but new insights into immune regulation are fundamental for developing more efficient therapies. c-MET signaling has been implicated in the migratory capacity and effector functions of immune cells. Nevertheless, the role of this signaling pathway in the context of PF-associated lung diseases remains unexplored.

METHODS

To determine the influence of c-MET in immune cells in the progression of pulmonary fibrosis, we used a conditional deletion of c-Met in immune cells. To induce pulmonary fibrosis mice were administered with bleomycin (BLM) intratracheally. Over the course of 21 days, mice were assessed for weight change, and after euthanasia at different timepoints, bronchoalveolar lavage fluid cells and lung tissue were assessed for inflammation and fibrosis. Furthermore, c-MET expression was assessed in cryobiopsy sections, bronchoalveolar lavage fluid cells samples and single cell RNA-sequencing dataset from human patients with distinct interstitial lung diseases.

RESULTS

c-MET expression was induced in lung immune cells, specifically in T cells, interstitial macrophages, and neutrophils, during the inflammatory phase of BLM-induced PF mouse model. Deletion of c-Met in immune cells correlated with earlier weight recovery and improved survival of BLM-treated mice. Moreover, the deletion of c-Met in immune cells was associated with early recruitment of the immune cell populations, normally found to express c-MET, leading to a subsequent attenuation of the cytotoxic and proinflammatory environment. Consequently, the less extensive inflammatory response, possibly coupled with tissue repair, culminated in less exacerbated fibrotic lesions. Furthermore, c-MET expression was up-regulated in lung T cells from patients with fibrosing ILD, suggesting a potential involvement of c-MET in the development of fibrosing disease.

CONCLUSIONS

These results highlight the critical contribution of c-MET signaling in immune cells to their enhanced uncontrolled recruitment and activation toward a proinflammatory and profibrotic phenotype, leading to the exacerbation of lung injury and consequent development of fibrosis.

Further knowledge and developments in resistance mechanisms to immune checkpoint inhibitors

The past decade has witnessed a revolution in cancer treatment, shifting from conventional drugs (chemotherapies) towards targeted molecular therapies and immune-based therapies, in particular immune-checkpoint inhibitors (ICIs). These immunotherapies release the host's immune system against the tumor and have shown unprecedented durable remission for patients with cancers that were thought incurable, such as metastatic melanoma, metastatic renal cell carcinoma (RCC), microsatellite instability (MSI) high colorectal cancer and late stages of non-small cell lung cancer (NSCLC). However, about 80% of the patients fail to respond to these immunotherapies and are therefore left with other less effective and potentially toxic treatments. Identifying and understanding the mechanisms that enable cancerous cells to adapt to and eventually overcome therapy can help circumvent resistance and improve treatment. In this review, we describe the recent discoveries on the onco-immunological processes which govern the tumor microenvironment and their impact on the resistance to PD-1/PD-L1 checkpoint blockade.

Neutrophil-mediated hypoxia drives pathogenic CD8+ T cell responses in cutaneous leishmaniasis

Cutaneous leishmaniasis caused by Leishmania parasites exhibits a wide range of clinical manifestations. Although parasites influence disease severity, cytolytic CD8+ T cell responses mediate disease. Although these responses originate in the lymph node, we found that expression of the cytolytic effector molecule granzyme B was restricted to lesional CD8+ T cells in Leishmania-infected mice, suggesting that local cues within inflamed skin induced cytolytic function. Expression of Blimp-1 (Prdm1), a transcription factor necessary for cytolytic CD8+ T cell differentiation, was driven by hypoxia within the inflamed skin. Hypoxia was further enhanced by the recruitment of neutrophils that consumed oxygen to produce ROS and ultimately increased the hypoxic state and granzyme B expression in CD8+ T cells. Importantly, lesions from patients with cutaneous leishmaniasis exhibited hypoxia transcription signatures that correlated with the presence of neutrophils. Thus, targeting hypoxia-driven signals that support local differentiation of cytolytic CD8+ T cells may improve the prognosis for patients with cutaneous leishmaniasis, as well as for other inflammatory skin diseases in which cytolytic CD8+ T cells contribute to pathogenesis.

MET Oncogene Targeting for Cancer Immunotherapy

The MET receptor is one of the main drivers of 'invasive growth', a multifaceted biological response essential during embryonic development and tissue repair that is usurped by cancer cells to induce and sustain the malignant phenotype. MET stands out as one of the most important oncogenes activated in cancer and its inhibition has been explored since the initial era of cancer-targeted therapy. Different approaches have been developed to hamper MET signaling and/or reduce MET (over)expression as a hallmark of transformation. Considering the great interest gained by cancer immunotherapy, this review evaluates the opportunity of targeting MET within therapeutic approaches based on the exploitation of immune functions, either in those cases where MET impairment is crucial to induce an effective response (i.e., when MET is the driver of the malignancy), or when blocking MET represents a way for potentiating the treatment (i.e., when MET is an adjuvant of tumor fitness).

Capmatinib plus nivolumab in pretreated patients with EGFR wild-type advanced non-small cell lung cancer

INTRODUCTION

Dysregulated MET is an established oncogenic driver in non-small cell lung cancer (NSCLC). MET signaling may also suppress anticancer immune responses. Concomitant MET inhibition with capmatinib (a MET inhibitor) synergistically enhanced the efficacy of immunotherapies in murine cancer models, regardless of tumor dependency to MET signaling. Here, we report results of a multicenter, open-label, phase 2 study of capmatinib plus nivolumab (a PD-1 inhibitor) in patients with EGFR wild-type advanced NSCLC, previously treated with platinum-based chemotherapy.

METHODS

Patients were allocated into high-MET or low-MET groups according to MET expression determined by immunohistochemistry, MET gene copy number as assessed by fluorescence in-situ hybridization, and presence of MET exon 14 skipping mutation, then received capmatinib 400 mg, oral, twice daily in combination with nivolumab 3 mg/kg intravenously every 2 weeks. The primary endpoint was investigator-assessed 6-month progression-free survival (PFS) rate per RECIST v1.1.

RESULTS

The primary endpoint was met in both the high-MET (N = 16) and low-MET (N = 30) groups. In the high-MET and low-MET groups, respectively, the estimated mean 6-month PFS rate (95 % credible interval) by Bayesian analysis was 68.9 % (48.5-85.7) and 50.9 % (35.6-66.4). The Kaplan-Meier median PFS (95 % CI) was 6.2 months (3.5-19.2) and 4.2 months (1.8-7.4). The overall response rate (95 % CI) was 25.0 % (7.3-52.4) and 16.7 % (5.6-34.7). Most frequent treatment-related adverse events (≥30 % any grade, N = 46) were nausea (52.2 %), peripheral edema (34.8 %), and increased blood creatinine (30.4 %).

CONCLUSIONS

Capmatinib plus nivolumab showed clinical activity and manageable safety in pretreated patients with advanced EGFR wild-type NSCLC, independent of MET status.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02323126.

Serum cytokines and creatinine/cystatin C ratio as prognostic biomarkers in advanced cancer patients treated with anti-PD-1/PD-L1 therapy

OBJECTIVE

Immune checkpoint inhibitors (ICIs), specifically targeting the programmed cell death protein-1 or its ligand (PD-1/PD-L1), have been extensively used in the treatment of a spectrum of malignancies, although the predictive biomarkers remain to be elucidated. This study aims to investigate the association between baseline circulating levels of cytokines and the creatinine/cystatin C ratio (CCR) with the treatment outcomes of ICIs in patients with advanced cancer.

METHODS

The pre-treatment circulating levels of 10 cytokines (PD-L1, CTLA4, CXCL10, LAG3, HGF, CCL2, MIG, GRANB, IL-18, and IL-6) were measured via automated capillary-based immunoassay platform in the serum of 65 advanced cancer patients treated with anti-PD-1/PD-L1-based systemic therapy and 10 healthy volunteers. The levels of cytokines and CCR were quantified and categorized into high and low groups based on the median value. The associations of serum cytokines and CCR with response to treatment, survival, and immune-related adverse events were assessed.

RESULTS

Elevated circulating levels of 6 cytokines (PD-L1, CXCL10, HGF, CCL2, MIG, and IL-6) were observed in cancer patients compared with that in healthy volunteers. The correlation coefficients between cytokines, CCR and nutritional risk index were also calculated. In the cancer cohort (N = 65), low circulating HGF (P = 0.023, P = 0.029), low IL-6 (P = 0.002, P < 0.001), and high CCR (P = 0.031, P = 0.008) were associated with significantly improved progression-free survival (PFS) and overall survival (OS). Multi-variable COX analyses adjusted for clinicopathological factors revealed that low HGF, low IL-6, and high CCR were independent favorable prognostic factors for PFS (P = 0.028, P = 0.010, and P = 0.015, respectively) and OS (P = 0.043, P = 0.003, and P = 0.026, respectively). Grade 2 irAEs occurred more frequently in patients with low levels of circulating CCL2 and LAG3.

CONCLUSIONS

Pre-treatment circulating levels of serum IL-6, HGF, and CCR may serve as independent predictive and prognostic biomarkers in advanced cancer patients treated with ICIs-based systemic therapy. These findings might help to identify potential patients who would benefit from these therapies.

Tumor-neutrophil cross talk orchestrates the tumor microenvironment to determine the bladder cancer progression

The immune landscape of bladder cancer progression is not fully understood, and effective therapies are lacking in advanced bladder cancer. Here, we visualized that bladder cancer cells recruited neutrophils by secreting interleukin-8 (IL-8); in turn, neutrophils played dual functions in bladder cancer, including hepatocyte growth factor (HGF) release and CCL3highPD-L1high super-immunosuppressive subset formation. Mechanistically, c-Fos was identified as the mediator of HGF up-regulating IL-8 transcription in bladder cancer cells, which was central to the positive feedback of neutrophil recruitment. Clinically, compared with serum IL-8, urine IL-8 was a better biomarker for bladder cancer prognosis and clinical benefit of immune checkpoint blockade (ICB). Additionally, targeting neutrophils or hepatocyte growth factor receptor (MET) signaling combined with ICB inhibited bladder cancer progression and boosted the antitumor effect of CD8+ T cells in mice. These findings reveal the mechanism by which tumor-neutrophil cross talk orchestrates the bladder cancer microenvironment and provide combination strategies, which may have broad impacts on patients suffering from malignancies enriched with neutrophils.

Neutrophils in glioma microenvironment: from immune function to immunotherapy

Glioma is a malignant tumor of the central nervous system (CNS). Currently, effective treatment options for gliomas are still lacking. Neutrophils, as an important member of the tumor microenvironment (TME), are widely distributed in circulation. Recently, the discovery of cranial-meningeal channels and intracranial lymphatic vessels has provided new insights into the origins of neutrophils in the CNS. Neutrophils in the brain may originate more from the skull and adjacent vertebral bone marrow. They cross the blood-brain barrier (BBB) under the action of chemokines and enter the brain parenchyma, subsequently migrating to the glioma TME and undergoing phenotypic changes upon contact with tumor cells. Under glycolytic metabolism model, neutrophils show complex and dual functions in different stages of cancer progression, including participation in the malignant progression, immune suppression, and anti-tumor effects of gliomas. Additionally, neutrophils in the TME interact with other immune cells, playing a crucial role in cancer immunotherapy. Targeting neutrophils may be a novel generation of immunotherapy and improve the efficacy of cancer treatments. This article reviews the molecular mechanisms of neutrophils infiltrating the central nervous system from the external environment, detailing the origin, functions, classifications, and targeted therapies of neutrophils in the context of glioma.

A phase Ib/II trial of capmatinib plus spartalizumab vs. spartalizumab alone in patients with pretreated hepatocellular carcinoma

Background & aims

This phase Ib/II trial evaluated the safety and efficacy of capmatinib in combination with spartalizumab or spartalizumab alone in patients with advanced hepatocellular carcinoma (HCC).

Methods

Eligible patients who had progressed or were intolerant to sorafenib received escalating doses of capmatinib 200 mg, 300 mg, and 400 mg twice a day (bid) plus spartalizumab 300 mg every 3 weeks (q3w) in the phase Ib study. Once the recommended phase II dose (RP2D) was determined, the phase II study commenced with randomised 1:1 treatment with either capmatinib + spartalizumab (n = 32) or spartalizumab alone (n = 30). Primary endpoints were safety and tolerability (phase Ib) and investigator-assessed overall response rate per RECIST v1.1 for combination vs. single-agent arms using a Bayesian logistic regression model (phase II).

Results

In phase Ib, the RP2D for capmatinib in combination with spartalizumab was determined to be 400 mg bid. Dose-limiting toxicity consisting of grade 3 diarrhoea was reported in one patient at the capmatinib 400 mg bid + spartalizumab 300 mg q3w dose level. The primary endpoint in the phase II study was not met. The observed overall response rate in the capmatinib + spartalizumab arm was 9.4% vs. 10% in the spartalizumab arm. The most common any-grade treatment-related adverse events (TRAEs, ≥20%) were nausea (37.5%), asthenia and vomiting (28.1% each), diarrhoea, pyrexia, and decreased appetite (25.0% each) in the combination arm; TRAEs ≥10% were pruritus (23.3%), and rash (10.0%) in the spartalizumab-alone arm.

Conclusion

Capmatinib at 400 mg bid plus spartalizumab 300 mg q3w was established as the RP2D, with manageable toxicities and no significant safety signals, but the combination did not show superior clinical activity compared with spartalizumab single-agent treatment in patients with advanced HCC who had previously been treated with sorafenib.

Impact and implications

Simultaneous targeting of MET and programmed cell death protein 1 may provide synergistic clinical benefit in patients with advanced HCC. This is the first trial to report a combination of capmatinib (MET inhibitor) and spartalizumab (programmed cell death protein 1 inhibitor) as second-line treatment after sorafenib for advanced HCC. The combination did not show superior clinical activity compared with spartalizumab single-agent treatment in patients with advanced HCC who had previously been treated with sorafenib. The results indicate that there is a clear need to identify a reliable predictive marker of response for HCC and to identify patients with HCC that would benefit from the combination of checkpoint inhibitor +/- targeted therapy.

Clinical trial number

NCT02795429.

Whole blood coagulation in an ex vivo thrombus is sufficient to induce clot neutrophils to adopt a myeloid-derived suppressor cell signature and shed soluble Lox-1

BACKGROUND

Blood clots are living tissues that release inflammatory mediators including IL-8/CXCL8 and MCP-1/CCL2. A deeper understanding of blood clots is needed to develop new therapies for prothrombotic disease states and regenerative medicine.

OBJECTIVES

To identify a common transcriptional shift in cultured blood clot leukocytes.

METHODS

Differential gene expression of whole blood and cultured clots (4 hours at 37 °C) was assessed by RNA sequencing (RNAseq), reverse transcriptase-polymerase chain reaction, proteomics, and histology (23 diverse healthy human donors). Cultured clot serum bioactivity was tested in endothelial barrier functional assays.

RESULTS

All cultured clots developed a polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC) signature, including up-regulation of OLR1 (mRNA encoding lectin-like oxidized low-density lipoprotein receptor 1 [Lox-1]), IL-8/CXCL8, CXCL2, CCL2, IL10, IL1A, SPP1, TREM1, and DUSP4/MKP. Lipopolysaccharide enhanced PMN-MDSC gene expression and specifically induced a type II interferon response with IL-6 production. Lox-1 was specifically expressed by cultured clot CD15+ neutrophils. Cultured clot neutrophils, but not activated platelets, shed copious amounts of soluble Lox-1 (sLox-1) with a donor-dependent amplitude. sLox-1 shedding was enhanced by phorbol ester and suppressed by heparin and by beta-glycerol phosphate, a phosphatase inhibitor. Cultured clot serum significantly enhanced endothelial cell monolayer barrier function, consistent with a proresolving bioactivity.

CONCLUSION

This study suggests that PMN-MDSC activation is part of the innate immune response to coagulation which may have a protective role in inflammation. The cultured blood clot is an innovative thrombus model that can be used to study both sterile and nonsterile inflammatory states and could be used as a personalized medicine tool for drug screening.

Neutrophils at the Crossroads: Unraveling the Multifaceted Role in the Tumor Microenvironment

Over the past decade, research has prominently established neutrophils as key contributors to the intricate landscape of tumor immune biology. As polymorphonuclear granulocytes within the innate immune system, neutrophils play a pivotal and abundant role, constituting approximately ∼70% of all peripheral leukocytes in humans and ∼10-20% in mice. This substantial presence positions them as the frontline defense against potential threats. Equipped with a diverse array of mechanisms, including reactive oxygen species (ROS) generation, degranulation, phagocytosis, and the formation of neutrophil extracellular traps (NETs), neutrophils undeniably serve as indispensable components of the innate immune system. While these innate functions enable neutrophils to interact with adaptive immune cells such as T, B, and NK cells, influencing their functions, they also engage in dynamic interactions with rapidly dividing tumor cells. Consequently, neutrophils are emerging as crucial regulators in both pro- and anti-tumor immunity. This comprehensive review delves into recent research to illuminate the multifaceted roles of neutrophils. It explores their diverse functions within the tumor microenvironment, shedding light on their heterogeneity and their impact on tumor recruitment, progression, and modulation. Additionally, the review underscores their potential anti-tumoral capabilities. Finally, it provides valuable insights into clinical therapies targeting neutrophils, presenting a promising approach to leveraging innate immunity for enhanced cancer treatment.

Epithelial-to-mesenchymal transition in cancer progression: unraveling the immunosuppressive module driving therapy resistance

Cancer cells undergo phenotypic switching (cancer cell plasticity) in response to microenvironmental cues, including exposure to therapy/treatment. Phenotypic plasticity enables the cancer cells to acquire more mesenchymal traits promoting cancer cells' growth, survival, therapy resistance, and disease recurrence. A significant program in cancer cell plasticity is epithelial-to-mesenchymal transition (EMT), wherein a comprehensive reprogramming of gene expression occurs to facilitate the translational shift from epithelial-to-mesenchymal phenotypes resulting in increased invasiveness and metastasis. In addition, EMT plays a pivotal role in facilitating cancer cells' escape from the body's immune system using several mechanisms, such as the downregulation of major histocompatibility complex-mediated antigen presentation, upregulation of immune checkpoint molecules, and recruitment of immune-suppressive cells. Cancer cells' ability to undergo phenotypic switching and EMT-driven immune escape presents a formidable obstacle in cancer management, highlighting the need to unravel the intricate mechanisms underlying these processes and develop novel therapeutic strategies. This article discusses the role of EMT in promoting immune evasion and therapy resistance. We also discuss the ongoing research on developing therapeutic approaches targeting intrinsic and induced cell plasticity within the immune suppressive microenvironment. We believe this review article will update the current research status and equip researchers, clinicians, and other healthcare professionals with valuable insights enhancing their existing knowledge and shedding light on promising directions for future cancer research. This will facilitate the development of innovative strategies for managing therapy-resistant cancers and improving patient outcomes.

Pathogenic CD8 T cell responses are driven by neutrophil-mediated hypoxia in cutaneous leishmaniasis

Cutaneous leishmaniasis caused by Leishmania parasites exhibits a wide range of clinical manifestations. Although parasites influence disease severity, cytolytic CD8 T cell responses mediate disease. While these responses originate in the lymph node, we find that expression of the cytolytic effector molecule granzyme B is restricted to lesional CD8 T cells in Leishmania - infected mice, suggesting that local cues within inflamed skin induce cytolytic function. Expression of Blimp-1 ( Prdm1 ), a transcription factor necessary for cytolytic CD8 T cell differentiation, is driven by hypoxia within the inflamed skin. Hypoxia is further enhanced by the recruitment of neutrophils that consume oxygen to produce reactive oxygen species, ultimately increasing granzyme B expression in CD8 T cells. Importantly, lesions from cutaneous leishmaniasis patients exhibit hypoxia transcription signatures that correlate with the presence of neutrophils. Thus, targeting hypoxia-driven signals that support local differentiation of cytolytic CD8 T cells may improve the prognosis for patients with cutaneous leishmaniasis, as well as other inflammatory skin diseases where cytolytic CD8 T cells contribute to pathogenesis.

Exploring the Role of Immunotherapy-Based Treatments for Advanced Non-Small-Cell Lung Cancer With Novel Driver Alterations

BACKGROUND

Immunotherapy (IO) single agent or combined with chemotherapy (CT-IO) is the standard treatment for advanced non-small-cell lung cancer (aNSCLC) without driver alterations. IO efficacy in patients with novel driver alterations is not well reported.

MATERIALS AND METHODS

Data of aNSCLC patients treated with IO or CT-IO in any line from January 2016 to September 2022 were retrospectively collected. Patients harboring novel driver alterations (m-cohort), including MET exon 14 skipping, BRAF (V600E or atypical), RET rearrangements, HER2 point mutations/exon 20 insertions or uncommon EGFR mutations/EGFR exon 20 insertions, and wild type patients (wt-cohort) were eligible. Clinico-pathological data were extracted from Institutional databases and compared through chi square or Fisher's exact test. Survivals were estimated through Kaplan-Meier method and compared by log-rank test.

RESULTS

m-cohort and wt-cohort included 84 and 444 patients, respectively. Progression free survival (PFS) was 5.53 vs. 4.57 months (P= .846) and overall survival (OS) was 25.1 vs. 9.37 months, (P < .0001) for m-cohort compared to wt-cohort. Within the m-cohort, BRAF atypical mutations had the better outcomes (Overall Response Rate [ORR], PFS), targeted agents timing did not affect response to IO and CT-IO had better ORR and disease control rate (DCR) compared to IO single agent (P = .0160 and P = .0152). In the PD-L1≥50% group, first line IO single agent resulted in inferior ORR (P = .027) and PFS (P = .022) in m-cohort compared to wt-cohort.

CONCLUSION

IO based treatments seem not detrimental for patients harboring novel driver alteration. Adding CT could improve modest responses to IO alone. Confirmation on larger datasets is required.

The development of amivantamab for the treatment of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) patients with sensitizing oncogenic driver mutations benefit from targeted therapies. Tyrosine kinase inhibitors are highly effective against classic sensitizing epidermal growth factor receptor (EGFR) mutations, such as exon 19 deletions and exon 21 L858R point mutations. Conversely, EGFR exon 20 insertions (exon20ins) are resistant to the traditional EGFR tyrosine kinase inhibitors (TKIs). In May 2021, the US Federal Drug Administration (FDA) provided accelerated approval to amivantamab (Rybrevant) in adults with locally advanced or metastatic NSCLC with EGFR exon20ins after treatment with platinum-based chemotherapy. Amivantamab was the first EGFR/MET bispecific antibody to be approved specifically for EGFR exon20ins where there was an unmet need. Furthermore, amivantamab is being evaluated in additional settings such as post osimertinib in sensitizing EGFR mutations as well as in MET altered NSCLC. Here we discuss amivantamab in regard to its mechanism of action, preclinical and clinical data, and clinical impact for patients with EGFR exon20ins NSCLC and beyond.

The local microenvironment drives activation of neutrophils in human brain tumors

Neutrophils are abundant immune cells in the circulation and frequently infiltrate tumors in substantial numbers. However, their precise functions in different cancer types remain incompletely understood, including in the brain microenvironment. We therefore investigated neutrophils in tumor tissue of glioma and brain metastasis patients, with matched peripheral blood, and herein describe the first in-depth analysis of neutrophil phenotypes and functions in these tissues. Orthogonal profiling strategies in humans and mice revealed that brain tumor-associated neutrophils (TANs) differ significantly from blood neutrophils and have a prolonged lifespan and immune-suppressive and pro-angiogenic capacity. TANs exhibit a distinct inflammatory signature, driven by a combination of soluble inflammatory mediators including tumor necrosis factor alpha (TNF-ɑ) and Ceruloplasmin, which is more pronounced in TANs from brain metastasis versus glioma. Myeloid cells, including tumor-associated macrophages, emerge at the core of this network of pro-inflammatory mediators, supporting the concept of a critical myeloid niche regulating overall immune suppression in human brain tumors.

Immune-Based Combination Therapies for Advanced Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fourth most frequent cause of cancer-related death worldwide. HCC frequently presents as advanced disease at diagnosis, and disease relapse following radical surgery is frequent. In recent years, immune checkpoint inhibitors (ICIs) have revolutionized the treatment of advanced HCC, particularly with the introduction of atezolizumab/bevacizumab as the new standard of care for first-line treatment. Recently, dual immune checkpoint blockade with durvalumab plus tremelimumab has also emerged as an effective first-line treatment for advanced HCC and most of the research is currently focused on developing combination treatments based mainly on ICIs. In this review, we will discuss the rationale and ongoing clinical trials of immune-based combination therapies for the treatment of advanced HCC, also focusing on new immunotherapy strategies such as chimeric antigen receptor T cells (CAR-T) and anti-cancer vaccines.

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.

Targeting MET: Discovery of Small Molecule Inhibitors as Non-Small Cell Lung Cancer Therapy

MET has been considered as a promising drug target for the treatment of MET-dependent diseases, particularly non-small cell lung cancer (NSCLC). Small molecule MET inhibitors with mainly three types of binding modes (Ia/Ib, II, and III) have been developed. In this Review, we provide an overview of the structural features, activation mechanism, and dysregulation pathway of MET and summarize progress on the development and discovery strategies utilized for MET inhibitors as well as mechanisms of acquired resistance to current approved inhibitors. The insights will accelerate discovery of new generation MET inhibitors to overcome clinical acquired resistance.

c-Met Mediated Cytokine Network Promotes Brain Metastasis of Breast Cancer by Remodeling Neutrophil Activities

The brain is one of the most common metastatic sites among breast cancer patients, especially in those who have Her2-positive or triple-negative tumors. The brain microenvironment has been considered immune privileged, and the exact mechanisms of how immune cells in the brain microenvironment contribute to brain metastasis remain elusive. In this study, we found that neutrophils are recruited and influenced by c-Met high brain metastatic cells in the metastatic sites, and depletion of neutrophils significantly suppressed brain metastasis in animal models. Overexpression of c-Met in tumor cells enhances the secretion of a group of cytokines, including CXCL1/2, G-CSF, and GM-CSF, which play critical roles in neutrophil attraction, granulopoiesis, and homeostasis. Meanwhile, our transcriptomic analysis demonstrated that conditioned media from c-Met high cells significantly induced the secretion of lipocalin 2 (LCN2) from neutrophils, which in turn promotes the self-renewal of cancer stem cells. Our study unveiled the molecular and pathogenic mechanisms of how crosstalk between innate immune cells and tumor cells facilitates tumor progression in the brain, which provides novel therapeutic targets for treating brain metastasis.

Neutrophil diversity in inflammation and cancer

Neutrophils are the most abundant circulating leukocytes in humans and the first immune cells recruited at the site of inflammation. Classically perceived as short-lived effector cells with limited plasticity and diversity, neutrophils are now recognized as highly heterogenous immune cells, which can adapt to various environmental cues. In addition to playing a central role in the host defence, neutrophils are involved in pathological contexts such as inflammatory diseases and cancer. The prevalence of neutrophils in these conditions is usually associated with detrimental inflammatory responses and poor clinical outcomes. However, a beneficial role for neutrophils is emerging in several pathological contexts, including in cancer. Here we will review the current knowledge of neutrophil biology and heterogeneity in steady state and during inflammation, with a focus on the opposing roles of neutrophils in different pathological contexts.

Glucocorticoid activation by HSD11B1 limits T cell-driven interferon signaling and response to PD-1 blockade in melanoma

BACKGROUND

Immune responses against tumors are subject to negative feedback regulation. Immune checkpoint inhibitors (ICIs) blocking Programmed cell death protein 1 (PD-1), a receptor expressed on T cells, or its ligand PD-L1 have significantly improved the treatment of cancer, in particular malignant melanoma. Nevertheless, responses and durability are variables, suggesting that additional critical negative feedback mechanisms exist and need to be targeted to improve therapeutic efficacy.

METHODS

We used different syngeneic melanoma mouse models and performed PD-1 blockade to identify novel mechanisms of negative immune regulation. Genetic gain-of-function and loss-of-function approaches as well as small molecule inhibitor applications were used for target validation in our melanoma models. We analyzed mouse melanoma tissues from treated and untreated mice by RNA-seq, immunofluorescence and flow cytometry to detect changes in pathway activities and immune cell composition of the tumor microenvironment. We analyzed tissue sections of patients with melanoma by immunohistochemistry as well as publicly available single-cell RNA-seq data and correlated target expression with clinical responses to ICIs.

RESULTS

Here, we identified 11-beta-hydroxysteroid dehydrogenase-1 (HSD11B1), an enzyme that converts inert glucocorticoids into active forms in tissues, as negative feedback mechanism in response to T cell immunotherapies. Glucocorticoids are potent suppressors of immune responses. HSD11B1 was expressed in different cellular compartments of melanomas, most notably myeloid cells but also T cells and melanoma cells. Enforced expression of HSD11B1 in mouse melanomas limited the efficacy of PD-1 blockade, whereas small molecule HSD11B1 inhibitors improved responses in a CD8+ T cell-dependent manner. Mechanistically, HSD11B1 inhibition in combination with PD-1 blockade augmented the production of interferon-γ by T cells. Interferon pathway activation correlated with sensitivity to PD-1 blockade linked to anti-proliferative effects on melanoma cells. Furthermore, high levels of HSD11B1, predominantly expressed by tumor-associated macrophages, were associated with poor responses to ICI therapy in two independent cohorts of patients with advanced melanomas analyzed by different methods (scRNA-seq, immunohistochemistry).

CONCLUSION

As HSD11B1 inhibitors are in the focus of drug development for metabolic diseases, our data suggest a drug repurposing strategy combining HSD11B1 inhibitors with ICIs to improve melanoma immunotherapy. Furthermore, our work also delineated potential caveats emphasizing the need for careful patient stratification.

Implication of changes in PD-L1 expression during neoadjuvant chemotherapy with docetaxel, cisplatin, and 5-fluorouracil (DCF) regimen in esophageal squamous cell carcinoma

BACKGROUND

Neoadjuvant docetaxel plus cisplatin and 5-FU (NAC-DCF) and adjuvant nivolumab monotherapy are the standard care for locally advanced resectable esophageal squamous cell carcinoma (ESCC). However, no effective biomarkers have been found in perioperative setting. We investigated how programmed death-ligand 1 (PD-L1) changes before and after NAC-DCF and how it relates to the therapeutic effect of NAC-DCF in resectable ESCC.

METHODS

PD-L1 expression in paired diagnostic biopsy and surgically resected tissues from ESCC patients who underwent surgical resection after receiving two or three NAC-DCF cycles was evaluated. PD-L1 positivity was defined as a combined positive score (CPS) of 10% ≤ . Gene expression analysis was conducted using samples before NAC-DCF.

RESULTS

Sixty-six paired samples from 33 patients were included in PD-L1 expression analysis, and 33 Pre-NAC samples acquired by diagnostic biopsy were included in gene expression analysis. Pretreatment, 3 (9%), 13 (39%), and 17 (52%) patients harbored tumors with CPS ranges of < 1%, 1%-10%, and 10% ≤ , respectively. After NAC-DCF, 5 (15%), 15 (45%), and 13 (39%) tumors presented CPS ranges of < 1%, 1%-10%, and 10% ≤ , respectively. The concordance rate between Pre-and Post-NAC-DCF samples was 45%. Patients with PD-L1-negative tumors both before and after NAC-DCF (n = 9) had shorter survival and different gene expression profile characterized by upregulation in WNT signaling or neutrophils.

CONCLUSIONS

A substantial PD-L1 expression alteration was observed, resulting in low concordance rate before and after NAC-DCF. Tumors persistently lacking PD-L1 had distinct gene expression profile with worse clinical outcomes, raising the need for further investigation.

Neutralization of NET-associated human ARG1 enhances cancer immunotherapy

Myeloid cells can restrain antitumor immunity by metabolic pathways, such as the degradation of l-arginine, whose concentrations are regulated by the arginase 1 (ARG1) enzyme. Results from preclinical studies indicate the important role of arginine metabolism in pancreatic ductal adenocarcinoma (PDAC) progression, suggesting a potential for clinical application; however, divergent evolution in ARG1 expression and function in rodents and humans has restricted clinical translation. To overcome this dichotomy, here, we show that neutrophil extracellular traps (NETs), released by spontaneously activated neutrophils isolated from patients with PDAC, create a microdomain where cathepsin S (CTSS) cleaves human (h)ARG1 into different molecular forms endowed with enhanced enzymatic activity at physiological pH. NET-associated hARG1 suppresses T lymphocytes whose proliferation is restored by either adding a hARG1-specific monoclonal antibody (mAb) or preventing CTSS-mediated cleavage, whereas small-molecule inhibitors are not effective. We show that ARG1 blockade, combined with immune checkpoint inhibitors, can restore CD8⁺ T cell function in ex vivo PDAC tumors. Furthermore, anti-hARG1 mAbs increase the frequency of adoptively transferred tumor-specific CD8⁺ T cells in tumor and enhance the effectiveness of immune checkpoint therapy in humanized mice. Thus, this study shows that extracellular ARG1, released by activated myeloid cells, localizes in NETs, where it interacts with CTSS that in turn cleaves ARG1, producing major molecular forms endowed with different enzymatic activity at physiological pH. Once exocytosed, ARG1 activity can be targeted by mAbs, which bear potential for clinical application for the treatment of PDAC and require further exploration.

Immunological and tumor-intrinsic mechanisms mediate the synergistic growth suppression of experimental glioblastoma by radiotherapy and MET inhibition

The hepatocyte growth factor (HGF)/MET signaling pathway has been proposed to be involved in the resistance to radiotherapy of glioblastoma via proinvasive and DNA damage response pathways.Here we assessed the role of the MET pathway in the response to radiotherapy in vitro and in vivo in syngeneic mouse glioma models. We find that the murine glioma cell lines GL-261, SMA-497, SMA-540 and SMA-560 express HGF and its receptor MET and respond to exogenous HGF with MET phosphorylation. Glioma cell viability or proliferation are unaffected by genetic or pharmacological MET inhibition using tepotinib or CRISPR/Cas9-engineered Met gene knockout and MET inhibition fails to sensitize glioma cells to irradiation in vitro. In contrast, the combination of tepotinib with radiotherapy prolongs survival of orthotopic SMA-560 or GL-261 glioma-bearing mice compared with radiotherapy or tepotinib treatment alone. Synergy is lost when such experiments are conducted in immunodeficient Rag1^-/- mice, and, importantly, also when Met gene expression is disrupted in the tumor cells. Combination therapy suppresses a set of pro-inflammatory mediators including matrix metalloproteases that are upregulated by radiotherapy alone and that have been linked to poor outcome in glioblastoma. Several of these mediators are positively regulated by transforming growth factor (TGF)-β, and pSMAD2 levels as a surrogate marker of TGF-β pathway activity are suppressed by combination treatment. We conclude that synergistic suppression of experimental syngeneic glioma growth by irradiation and MET inhibition requires MET expression in the tumor as well as an intact immune system. Clinical evaluation of this combined strategy in newly diagnosed glioblastoma is warranted.

Redox signaling in drug-tolerant persister cells as an emerging therapeutic target

Drug-tolerant persister (DTP) cells have attracted significant interest, given their predominant role in treatment failure. In this respect, DTP cells reportedly survive after anticancer drug exposure, and their DNA repair mechanisms are altered to enhance adaptive mutation, accounting for the emergence of drug-resistant mutations. DTP cells resume proliferation upon treatment withdrawal and are responsible for cancer relapse. Current evidence suggests that DTP cells mediate redox signaling-mediated cellular homeostasis by developing various adaptive mechanisms, especially metabolic reprogramming that promotes mitochondrial oxidative respiration and a robust antioxidant process. There is an increasing consensus that disrupting redox homeostasis by intervening with redox signaling is theoretically a promising therapeutic strategy for targeting these sinister cells. In this review, we provide a comprehensive overview of the characteristics of DTP cells and the underlying mechanisms involved in redox signaling, aiming to provide a unique perspective on potential therapeutic applications based on their vulnerabilities to redox regulation.

Durable Response to Chemoimmunotherapy of a Lung Adenocarcinoma Harboring a MET Exon 14 Skipping Mutation

Chemoimmunotherapy is the first-line standard treatment for patients with non-small cell lung cancer (NSCLC). However, there are few reports on the efficacy of chemoimmunotherapy in patients with NSCLC who harbor the MET exon 14 skipping mutation. We report the case of an 81-year-old male patient with lung adenocarcinoma with a MET exon 14 skipping mutation who was treated with chemoimmunotherapy and achieved a durable response. Chemoimmunotherapy may be a promising treatment option for patients with a MET exon 14 skipping mutation. However, further studies are needed to characterize the objective response rate and response duration in these populations.

Preclinical Characterization of XL092, a Novel Receptor Tyrosine Kinase Inhibitor of MET, VEGFR2, AXL, and MER

The multi-receptor tyrosine kinase inhibitor XL092 has been developed to inhibit the activity of oncogenic targets, including MET, VEGFR2, and the TAM family of kinases TYRO3, AXL and MER. Presented here is a preclinical evaluation of XL092. XL092 causes a significant decrease in tumor MET and AXL phosphorylation (P < 0.01) in murine Hs 746T xenograft models relative to vehicle, and a 96% inhibition of VEGFR2 phosphorylation in murine lungs. Dose-dependent tumor growth inhibition with XL092 was observed in various murine xenograft models, with dose-dependent tumor regression seen in the NCI-H441 model. Tumor growth inhibition was enhanced with the combination of XL092 with anti-PD-1, anti-programmed death ligand-1 (PD-L1), or anti-CTLA-4 compared with any of these agents alone in the MC38 murine syngeneic model and with anti-PD-1 in the CT26 colorectal cancer survival model. In vivo, XL092 promoted a decrease in the tumor microvasculature and significant increases of peripheral CD4+ T cells and B cells and decreases in myeloid cells versus vehicle. Significant increases in CD8+ T cells were also observed with XL092 plus anti-PD-1 or anti-PD-L1 versus vehicle. In addition, XL092 promoted M2 to M1 repolarization of macrophages in vitro and inhibited primary human macrophage efferocytosis in a dose-dependent manner. In summary, XL092 was shown to have significant antitumor and immunomodulatory activity in animal models both alone and in combination with immune checkpoint inhibitors, supporting its evaluation in clinical trials.

Blockade of neutrophil recruitment to tumor sites based on sialic acid-modified nanoplatforms enhances the efficacy of checkpoint blockade immunotherapy

Checkpoint inhibitors are designed to rejuvenate depleted or suppressed T cells in the tumor microenvironment, relying on the immune system to control and kill tumors. However, accumulating evidence indicates that tumor-infiltrating neutrophils impede the proliferation and activation of T cells and determine the resistance to checkpoint blockade and chemotherapy. In this study, sialic acid ligand-modified colchicine derivative phospholipid complexes specifically targeted tumor-associated neutrophils in the peripheral blood, blocked neutrophil accumulation in tumors, and attenuated the inhibitory effect of infiltrating neutrophils on T cells. Neutrophil blocking therapy enhanced the immunotherapy effect of the PD-L1 antibody in S180 advanced tumors and 4T1 breast cancer. Our study found that PD-L1 antibody monotherapy increased the tumor infiltration of immunosuppressive neutrophils. Combination therapy with neutrophil blocking can greatly reduce tumor-infiltrating neutrophils and increase the proliferation of cytotoxic CD8⁺ T lymphocytes in the tumor. The combination therapy significantly improved the survival rate of mice with advanced S180 tumors and increased the sensitivity of immune checkpoint inhibitors to 4T1 cold tumors.

Blocking the HGF-MET pathway induces resolution of neutrophilic inflammation by promoting neutrophil apoptosis and efferocytosis

Inflammation resolution is an active process that involves cellular events such as apoptosis and efferocytosis, which are key steps in the restoration of tissue homeostasis. Hepatocyte growth factor (HGF) is a growth factor mostly produced by mesenchymal-origin cells and has been described to act via MET receptor tyrosine kinase. The HGF/MET axis is essential for determining the progression and severity of inflammatory and immune-mediated disorders. Here, we investigated the effect of blocking the HGF/MET signalling pathway by PF-04217903 on the resolution of established models of neutrophilic inflammation. In a self-resolving model of gout induced by MSU crystals, HGF expression on periarticular tissue peaked at 12 h, the same time point that neutrophils reach their maximal accumulation in the joints. The HGF/MET axis was activated in this model, as demonstrated by increased levels of MET phosphorylation in neutrophils (Ly6G⁺ cells). In addition, the number of neutrophils was reduced in the knee exudate after PF-04217903 treatment, an effect accompanied by increased neutrophil apoptosis and efferocytosis and enhanced expression of Annexin A1, a key molecule for inflammation resolution. Reduced MPO activity, IL-1β and CXCL1 levels were also observed in periarticular tissue. Importantly, PF-04217903 reduced the histopathological score and hypernociceptive response. Similar findings were obtained in LPS-induced neutrophilic pleurisy. In human neutrophils, the combined use of LPS and HGF increased MET phosphorylation and provided a prosurvival signal, whereas blocking MET with PF-04217903 induced caspase-dependent neutrophil apoptosis. Taken together, these data demonstrate that blocking HGF/MET signalling may be a potential therapeutic strategy for inducing the resolution of neutrophilic inflammatory responses.

Targeting the cMET pathway to enhance immunotherapeutic approaches for mUM patients

The liver is the most preferential initial site of metastasis for uveal melanoma (mUM), and this preference is associated with rapid mortality in mUM patients. Despite the significant clinical benefits of Immune checkpoint inhibitors (ICIs) in metastatic cutaneous melanoma patients, ICIs have shown little to no benefit in mUM patients. A potential reason for this inefficiency of ICI could be partly devoted to the involvement of the liver itself, thanks to its rich source of growth factors and immunosuppressive microenvironment. Uveal melanoma cells show increased expression of a transmembrane protein called cMET, which is known as the sole receptor for the Hepatocyte growth factor (HGF). Hyperactivation of cMET by HGF contributes to mUM development, and the liver, being the major source of HGF, may partially explain the metastasis of uveal melanoma cells to the liver. In addition, cMET/HGF signaling has also been shown to mediate resistance to ICI treatment, directly and indirectly, involving tumor and immune cell populations. Therefore, targeting the cMET/HGF interaction may enhance the efficacy of immunotherapeutic regimes for mUM patients. Hence in this minireview, we will discuss the rationale for combining cMET inhibitors/antibodies with leading immune checkpoint inhibitors for treating mUM. We will also briefly highlight the challenges and opportunities in targeting cMET in mUM.

N1 versus N2 and PMN-MDSC: A critical appraisal of current concepts on tumor-associated neutrophils and new directions for human oncology

Research on tumor-associated neutrophils (TAN) currently surges because of the well-documented strong clinical relevance of tumor-infiltrating neutrophils. This relevance is illustrated by strong correlations between high frequencies of intratumoral neutrophils and poor outcome in the majority of human cancers. Recent high-dimensional analysis of murine neutrophils provides evidence for unexpected plasticity of neutrophils in murine models of cancer and other inflammatory non-malignant diseases. New analysis tools enable deeper insight into the process of neutrophil differentiation and maturation. These technological and scientific developments led to the description of an ever-increasing number of distinct transcriptional states and associated phenotypes in murine models of disease and more recently also in humans. At present, functional validation of these different transcriptional states and potential phenotypes in cancer is lacking. Current functional concepts on neutrophils in cancer rely mainly on the myeloid-derived suppressor cell (MDSC) concept and the dichotomous and simple N1-N2 paradigm. In this manuscript, we review the historic development of those concepts, critically evaluate these concepts against the background of our own work and provide suggestions for a refinement of current concepts in order to facilitate the transition of TAN research from experimental insight to clinical translation.

Evolving therapeutic landscape of advanced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common solid malignancies worldwide. A large proportion of patients with HCC are diagnosed at advanced stages and are only amenable to systemic therapies. We have witnessed the evolution of systemic therapies from single-agent targeted therapy (sorafenib and lenvatinib) to the combination of a checkpoint inhibitor plus targeted therapy (atezolizumab plus bevacizumab therapy). Despite remarkable advances, only a small subset of patients can obtain durable clinical benefit, and therefore substantial therapeutic challenges remain. In the past few years, emerging systemic therapies, including new molecular-targeted monotherapies (for example, donafenib), new immuno-oncology monotherapies (for example, durvalumab) and new combination therapies (for example, durvalumab plus tremelimumab), have shown encouraging results in clinical trials. In addition, many novel therapeutic approaches with the potential to offer improved treatment effects in patients with advanced HCC, such as sequential combination targeted therapy and next-generation adoptive cell therapy, have also been proposed and developed. In this Review, we summarize the latest clinical advances in the treatment of advanced HCC and discuss future perspectives that might inform the development of more effective therapeutics for advanced HCC.