IL8, Neutrophils, and NETs in a Collusion against Cancer Immunity and Immunotherapy

Targeting IL8 as a sequential therapy strategy to overcome chemotherapy resistance in advanced gastric cancer

Systemic chemotherapy with multiple drug regimens is the main therapy option for advanced gastric cancer (GC) patients. However, many patients develop relapse soon. Here, we evaluated the therapeutic potential of targeting interleukin-8 (IL8) to overcome resistance to chemotherapy in advanced GC. RNA sequencing revealed crucial molecular changes after chemotherapy resistance, in which the expression of IL8 was significantly activated with the increase in drug resistance. Subsequently, the clinical significance of IL8 expression was determined in GC population specimens. IL8-targeted by RNA interference or reparixin reversed chemotherapy resistance with limited toxicity in vivo and vitro experiments. Sequential treatment with first-line, second-line chemotherapy and reparixin inhibited GC growth, reduced toxicity and prolonged survival. Collectively, our study provides a therapeutic strategy that targeting IL8 as a sequential therapy after chemotherapy resistance in advanced GC.

Potential Role of Neutrophil Extracellular Traps in Cardio-Oncology

Cardiovascular toxicity has emerged as the leading cause of death in patients undergoing cancer treatment. Thus, cardio-oncology (CO) care must also focus on the prevention and management of related cardiovascular (CV) complications caused by cancer therapy. Neutrophil extracellular traps (NETs)—entities with released DNA, proteases, proinflammatory and prooxidative substances from blasted neutrophils—play an important role in cancer proliferation, propagation metastasis, and incident CV events (acute coronary syndrome, thromboembolic events, and heart failure). Although NETs have been shown to be involved in cancer progression and incident CV events, little is known about their relationship with cardio-oncology, especially on cancer treatment-related cardiovascular toxicity (CTRCT). This review aims to explore the evidence of the impact of NETs on cancer, CV events, and CTRCT, and the possible solutions based on the mechanism of NETs activation and NETs released toxic substances.

NETosis and Neutrophil Extracellular Traps in COVID-19: Immunothrombosis and Beyond

Infection with SARS-CoV-2, the causative agent of the Coronavirus disease 2019 (COVID-19) pandemic, causes respiratory problems and multifaceted organ dysfunction. A crucial mechanism of COVID-19 immunopathy is the recruitment and activation of neutrophils at the infection site, which also predicts disease severity and poor outcomes. The release of neutrophil extracellular traps (NETs), occurring during a regulated form of neutrophil cell death known as NETosis, is a key effector function that mediates harmful effects caused by neutrophils. Abundant NETosis and NET generation have been observed in the neutrophils of many COVID-19 patients, leading to unfavorable coagulopathy and immunothrombosis. Moreover, excessive NETosis and NET generation are now more widely recognized as mediators of additional pathophysiological abnormalities following SARS-CoV-2 infection. In this minireview, we introduce subtypes of NET-producing neutrophils (e.g., low-density granulocytes) and explain the biological importance of NETs and the protein cargos of NETs in COVID-19. In addition, we discuss the mechanisms by which SARS-CoV-2 causes NETosis by upregulating viral processes (e.g., viral entry and replication) as well as host pro-NET mechanisms (e.g., proinflammatory mediator release, platelet activation, and autoantibody production). Furthermore, we provide an update of the main findings of NETosis and NETs in immunothrombosis and other COVID-19-related disorders, such as aberrant immunity, neurological disorders, and post COVID-19 syndromes including lung fibrosis, neurological disorder, tumor progression, and deteriorated chronic illness. Finally, we address potential prospective COVID-19 treatment strategies that target dysregulated NETosis and NET formation via inhibition of NETosis and promotion of NET degradation, respectively.

Neutrophil Extracellular Traps in Cancer Therapy Resistance

Neutrophils and their products are increasingly recognized to have a key influence on cancer progression and response to therapy. Their involvement has been shown in nearly every aspect of cancer pathophysiology with growing evidence now supporting their role in resistance to a variety of cancer therapies. Recently, the role of neutrophils in cancer progression and therapy resistance has been further complicated with the discovery of neutrophil extracellular traps (NETs). NETs are web-like structures of chromatin decorated with a variety of microbicidal proteins. They are released by neutrophils in a process called NETosis. NET-dependent mechanisms of cancer pathology are beginning to be appreciated, particularly with respect to tumor response to chemo-, immuno-, and radiation therapy. Several studies support the functional role of NETs in cancer therapy resistance, involving T-cell exhaustion, drug detoxification, angiogenesis, the epithelial-to-mesenchymal transition, and extracellular matrix remodeling mechanisms, among others. Given this, new and promising data suggests NETs provide a microenvironment conducive to limited therapeutic response across a variety of neoplasms. As such, this paper aims to give a comprehensive overview of evidence on NETs in cancer therapy resistance with a focus on clinical applicability.

Localized Degradation of Neutrophil Extracellular Traps by Photoregulated Enzyme Delivery for Cancer Immunotherapy and Metastasis Suppression

Extrusion of neutrophil extracellular traps (NETs), a fundamental host innate immune defense against pathogens, has recently been linked to cancer resistance to immunotherapy and distant metastasis. These findings highlight interesting areas of cancer-elicited inflammation and potential therapeutic strategies. Disrupting existing NETs with DNase I has been proved to enhance the therapeutic efficacy of tumor immunotherapy and attenuate metastatic spread. However, systemic biodistribution of DNase I raises safety issues, potentially impairing host defense against infection. Hence, tumor-specific delivery and metastatic niche-targeted effects are attractive options for localized degradation of NETs. We have engineered a nanoplatform with a plasmonic gold blackbody (AuPB) core with broad-spectrum photo activity and a mesoporous polydopamine (mPDA) shell for efficient loading and photoregulated release of DNase I. The on-demand released DNase I triggered by the second near-infrared (NIR-II) light irradiation breaks the "NET-mediated physical barrier", thereby increasing the contact of immune cytotoxic cells with tumor cells in living mice and sensitizing immune checkpoint therapy of primary colorectal cancer (CRC). Moreover, the deposition and light-controlled cargo release from systemically delivered AuPB@mPDA carriers in liver, the most frequent site of CRC metastasis, abolished NET-mediated capture of circulating tumor cells and hence metastatic seeding. Our findings indicate that the localized, light-regulated release of DNase I by photoactive carriers in the NIR-II window represent a translational route for immune-mediated tumor regression and metastasis inhibition.

Coagulome and the tumor microenvironment: an actionable interplay

Human tumors often trigger a hypercoagulable state that promotes hemostatic complications, including venous thromboembolism. The recent application of systems biology to the study of the coagulome highlighted its link to shaping the tumor microenvironment (TME), both within and outside of the vascular space. Addressing this link provides the opportunity to revisit the significance of biomarkers of hemostasis and assess the communication between vasculature and tumor parenchyma, an important topic considering the advent of immune checkpoint inhibitors and vascular normalization strategies. Understanding how the coagulome and TME influence each other offers exciting new prospects for predicting hemostatic complications and boosting the effectiveness of cancer treatment.

Casting a NET on cancer: the multiple roles for neutrophil extracellular traps in cancer

PURPOSE OF REVIEW

The role of the innate immune system has become widely appreciated in cancer and cancer-associated disorders. Neutrophils, the most abundant circulating leukocytes, have prognostic value in determining cancer progression and survival. One of the ways by which neutrophils negatively impact outcome is by formation of neutrophil extracellular traps (NETs) which result in release of nuclear chromatin and bioactive proteins into the extracellular space. Here, we review the evidence for NETs contributions to cancer progression, metastasis, and cancer-associated thrombosis (CAT).

RECENT FINDINGS

NETs are increased across several cancer types and predict progression and adverse outcome. Several preclinical and clinical observations implicate NETs in promoting tumor growth, angiogenesis and metastasis via distinct pathways. Furthermore, NETs are shown to contribute to resistance to immunotherapy. NETs also emerge as key players in the prothrombotic phenotype associated with cancer that can result in potentially life-threatening arterial and venous thrombosis. Recent mechanistic insights expose several potential targets to inhibit NET formation and disrupt the interaction between NETs and tumor cells.

SUMMARY

Clinical and translational insights highlight the central role of NETs in cancer progression and metastasis, disease resistance and CAT. Targeting NETs and NET-associated pathways may represent a novel approach to treat cancer.

Comorbidity-associated glutamine deficiency is a predisposition to severe COVID-19

SARS-CoV-2 vaccinations have greatly reduced COVID-19 cases, but we must continue to develop our understanding of the nature of the disease and its effects on human immunity. Previously, we suggested that a dysregulated STAT3 pathway following SARS-Co-2 infection ultimately leads to PAI-1 activation and cascades of pathologies. The major COVID-19-associated metabolic risks (old age, hypertension, cardiovascular diseases, diabetes, and obesity) share high PAI-1 levels and could predispose certain groups to severe COVID-19 complications. In this review article, we describe the common metabolic profile that is shared between all of these high-risk groups and COVID-19. This profile not only involves high levels of PAI-1 and STAT3 as previously described, but also includes low levels of glutamine and NAD+, coupled with overproduction of hyaluronan (HA). SARS-CoV-2 infection exacerbates this metabolic imbalance and predisposes these patients to the severe pathophysiologies of COVID-19, including the involvement of NETs (neutrophil extracellular traps) and HA overproduction in the lung. While hyperinflammation due to proinflammatory cytokine overproduction has been frequently documented, it is recently recognized that the immune response is markedly suppressed in some cases by the expansion and activity of MDSCs (myeloid-derived suppressor cells) and FoxP3+ Tregs (regulatory T cells). The metabolomics profiles of severe COVID-19 patients and patients with advanced cancer are similar, and in high-risk patients, SARS-CoV-2 infection leads to aberrant STAT3 activation, which promotes a cancer-like metabolism. We propose that glutamine deficiency and overproduced HA is the central metabolic characteristic of COVID-19 and its high-risk groups. We suggest the usage of glutamine supplementation and the repurposing of cancer drugs to prevent the development of severe COVID-19 pneumonia.

Phase I Study of Stereotactic Body Radiotherapy plus Nivolumab and Urelumab or Cabiralizumab in Advanced Solid Tumors

PURPOSE

CD137 agonism and CSF1R blockade augment stereotactic body radiotherapy (SBRT) and anti-programmed death-1 in preclinical models. We evaluated the safety and efficacy of SBRT with nivolumab+urelumab (CD137 agonist) or nivolumab+cabiralizumab (CSF1R inhibitor).

PATIENTS AND METHODS

This phase I clinical trial enrolled patients with advanced solid tumors that had progressed on standard therapies. SBRT was delivered to 1-4 metastases with nivolumab+urelumab or nivolumab+cabiralizumab given concurrently and following SBRT. Dose-limiting toxicity (DLT) was the primary endpoint with anatomic location-specific SBRT doses deemed safe if ≤33% DLT frequency was observed. Secondary endpoints included RECISTv1.1 response, progression-free survival (PFS), overall survival (OS), and molecular correlative studies.

RESULTS

Sixty patients were enrolled, and median follow-up for living patients is 13.8 months. Of these, 23 (38%) received SBRT+nivolumab+urelumab and 37 (62%) received SBRT+nivolumab+cabiralizumab. Seven patients (12%) experienced a DLT (n = 3 grade 3, n = 4 grade 4) in the following anatomic cohorts: abdominal/pelvic (3/17, 18%), liver (1/13, 8%), central lung (2/14, 14%), and peripheral lung (1/12, 8%). Of 41 patients radiographically evaluable for best overall response including 55 radiated and 23 unirradiated RECIST target lesions, 2 had complete responses (5%), 7 had partial responses (17%), 12 had stable disease (29%), and 20 had progression (49%). Median estimated PFS and OS are 3.0 months [95% confidence interval (CI), 2.9-4.8] and 17.0 months (95% CI, 6.8-undetermined), respectively. No patients with elevated pre-SBRT serum IL8 experienced a response.

CONCLUSIONS

SBRT to ≤4 sites with nivolumab+urelumab or nivolumab+cabiralizumab for treating advanced solid tumors is feasible with acceptable toxicity and modest antitumor activity.See related commentary by Rodriguez-Ruiz et al., p. 5443.

Firefighters for the Wrong Type of Inflammation in Tumors

In this issue of Cancer Discovery, Pelly and colleagues show that inhibition of prostaglandin E₂ synthesis or its activity on EP2 and EP4 receptors synergizes with anti-PD-1 immunotherapy and triggers a potent intratumoral IFNγ response in mouse models and in fresh surgical human tumor explants. This therapeutic strategy is in line with other interventions that aim at fostering immunotherapy by means of quenching protumor inflammation.See related article by Pelly et al., p. 2602.

The tumor microenvironment as driver of stemness and therapeutic resistance in breast cancer: New challenges and therapeutic opportunities

BACKGROUND

Breast cancer (BC), the second most common cause of cancer-related deaths, remains a significant threat to the health and wellness of women worldwide. The tumor microenvironment (TME), comprising cellular components, such as cancer-associated fibroblasts (CAFs), immune cells, endothelial cells and adipocytes, and noncellular components such as extracellular matrix (ECM), has been recognized as a critical contributor to the development and progression of BC. The interplay between TME components and cancer cells promotes phenotypic heterogeneity, cell plasticity and cancer cell stemness that impart tumor dormancy, enhanced invasion and metastasis, and the development of therapeutic resistance. While most previous studies have focused on targeting cancer cells with a dismal prognosis, novel therapies targeting stromal components are currently being evaluated in preclinical and clinical studies, and are already showing improved efficacies. As such, they may offer better means to eliminate the disease effectively.

CONCLUSIONS

In this review, we focus on the evolving concept of the TME as a key player regulating tumor growth, metastasis, stemness, and the development of therapeutic resistance. Despite significant advances over the last decade, several clinical trials focusing on the TME have failed to demonstrate promising effectiveness in cancer patients. To expedite clinical efficacy of TME-directed therapies, a deeper understanding of the TME is of utmost importance. Secondly, the efficacy of TME-directed therapies when used alone or in combination with chemo- or radiotherapy, and the tumor stage needs to be studied. Likewise, identifying molecular signatures and biomarkers indicating the type of TME will help in determining precise TME-directed therapies.

The Complement System in Ovarian Cancer: An Underexplored Old Path

Ovarian cancer is one of the most lethal gynecological cancers. Current therapeutic strategies allow temporary control of the disease, but most patients develop resistance to treatment. Moreover, although successful in a range of solid tumors, immunotherapy has yielded only modest results in ovarian cancer. Emerging evidence underscores the relevance of the components of innate and adaptive immunity in ovarian cancer progression and response to treatment. Particularly, over the last decade, the complement system, a pillar of innate immunity, has emerged as a major regulator of the tumor microenvironment in cancer immunity. Tumor-associated complement activation may support chronic inflammation, promote an immunosuppressive microenvironment, induce angiogenesis, and activate cancer-related signaling pathways. Recent insights suggest an important role of complement effectors, such as C1q or anaphylatoxins C3a and C5a, and their receptors C3aR and C5aR1 in ovarian cancer progression. Nevertheless, the implication of these factors in different clinical contexts is still poorly understood. Detailed knowledge of the interplay between ovarian cancer cells and complement is required to develop new immunotherapy combinations and biomarkers. In this context, we discuss the possibility of targeting complement to overcome some of the hurdles encountered in the treatment of ovarian cancer.

Neutrophils in the era of immune checkpoint blockade

The immune checkpoint blockade-based immunotherapies are revolutionizing cancer management. Tumor-associated neutrophils (TANs) were recently highlighted to have a pivotal role in modulating the tumor microenvironment and the antitumor immune response. However, these cells were largely ignored during the development of therapies based on programmed cell death receptor or ligand-1 and cytotoxic T lymphocyte antigen-4 immune checkpoint inhibitors (ICIs). Latest evidences of neutrophil functional diversity in tumor raised many questions and suggest that targeting these cells can offer new treatment opportunities in the context of ICI development. Here, we summarized key information on TAN origin, function, and plasticity that should be considered when developing ICIs and provide a detailed review of the ongoing clinical trials that combine ICIs and a second compound that might affect or be affected by TANs. This review article synthetizes important notions from the literature demonstrating that: (1) Cancer development associates with a profound alteration of neutrophil biogenesis and function that can predict and interfere with the response to ICIs, (2) Neutrophil infiltration in tumor is associated with key features of resistance to ICIs, and (3) TANs play an important role in resistance to antiangiogenic drugs reducing their clinical benefit when used in combination with ICIs. Finally, exploring the clinical/translational aspects of neutrophil impact on the response to ICIs offers the opportunity to propose new translational research avenues to better understand TAN biology and treat patients.

Neutrophil Extracellular Traps in Colorectal Cancer Progression and Metastasis

Neutrophils form sticky web-like structures known as neutrophil extracellular traps (NETs) as part of innate immune response. NETs are decondensed extracellular chromatin filaments comprising nuclear and cytoplasmic proteins. NETs have been implicated in many gastrointestinal diseases including colorectal cancer (CRC). However, the regulatory mechanisms of NET formation and potential pharmacological inhibitors in the context of CRC have not been thoroughly discussed. In this review, we intend to highlight roles of NETs in CRC progression and metastasis as well as the potential of targeting NETs during colon cancer therapy.

Tumor necrosis: A synergistic consequence of metabolic stress and inflammation

Tumor necrosis is a common histological feature and poor prognostic predictor in various cancers. Despite its significant clinical implications, the mechanism underlying tumor necrosis remains largely unclear due to lack of appropriate pre-clinical modeling. We propose that tumor necrosis is a synergistic consequence of metabolic stress and inflammation, which lead to oxidative stress-induced cell death, such as ferroptosis. As a natural consequence of tumor expansion, tumor cells are inevitably stripped of vascular supply, resulting in deprivation of oxygen and nutrients. The resulting metabolic stress has commonly been considered the cause of tumor necrosis. Recent studies found that immune cells, such as neutrophils, when recruited to tumors, can directly trigger ferroptosis in tumor cells, suggesting that immune cells can be involved in amplifying tumor necrosis. This article will discuss potential mechanisms underlying tumor necrosis development and its impact on tumor progression as well as the immune response to tumors.

Heterogenous presence of neutrophil extracellular traps in human solid tumours is partially dependent on IL-8

Neutrophil extracellular traps (NETs) are webs of extracellular nuclear DNA extruded by dying neutrophils infiltrating tissue. NETs constitute a defence mechanism to entrap and kill fungi and bacteria. Tumours induce the formation of NETs to the advantage of the malignancy via a variety of mechanisms shown in mouse models. Here, we investigated the presence of NETs in a variety of human solid tumours and their association with IL-8 (CXCL8) protein expression and CD8⁺ T-cell density in the tumour microenvironment. Multiplex immunofluorescence panels were developed to identify NETs in human cancer tissues by co-staining with the granulocyte marker CD15, the neutrophil marker myeloperoxidase and citrullinated histone H3 (H3Cit), as well as IL-8 protein and CD8⁺ T cells. Three ELISA methods to detect and quantify circulating NETs in serum were optimised and utilised. Whole tumour sections and tissue microarrays from patients with non-small cell lung cancer (NSCLC; n = 14), bladder cancer (n = 14), melanoma (n = 11), breast cancer (n = 31), colorectal cancer (n = 20) and mesothelioma (n = 61) were studied. Also, serum samples collected retrospectively from patients with metastatic melanoma (n = 12) and NSCLC (n = 34) were ELISA assayed to quantify circulating NETs and IL-8. NETs were detected in six different human cancer types with wide individual variation in terms of tissue density and distribution. At least in NSCLC, bladder cancer and metastatic melanoma, NET density positively correlated with IL-8 protein expression and inversely correlated with CD8⁺ T-cell densities. In a series of serum samples from melanoma and NSCLC patients, a positive correlation between circulating NETs and IL-8 was found. In conclusion, NETs are detectable in formalin-fixed human biopsy samples from solid tumours and in the circulation of cancer patients with a considerable degree of individual variation. NETs show a positive association with IL-8 and a trend towards a negative association with CD8⁺ tumour-infiltrating lymphocytes. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

A Signaling View into the Inflammatory Tumor Microenvironment

The development of tumors requires an initiator event, usually exposure to DNA damaging agents that cause genetic alterations such as gene mutations or chromosomal abnormalities, leading to deregulated cell proliferation. Although the mere stochastic accumulation of further mutations may cause tumor progression, it is now clear that an inflammatory microenvironment has a major tumor-promoting influence on initiated cells, in particular when a chronic inflammatory reaction already existed before the initiated tumor cell was formed. Moreover, inflammatory cells become mobilized in response to signals emanating from tumor cells. In both cases, the microenvironment provides signals that initiated tumor cells perceive by membrane receptors and transduce via downstream kinase cascades to modulate multiple cellular processes and respond with changes in cell gene expression, metabolism, and morphology. Cytokines, chemokines, and growth factors are examples of major signals secreted by immune cells, fibroblast, and endothelial cells and mediate an intricate cell-cell crosstalk in an inflammatory microenvironment, which contributes to increased cancer cell survival, phenotypic plasticity and adaptation to surrounding tissue conditions. Eventually, consequent changes in extracellular matrix stiffness and architecture, coupled with additional genetic alterations, further fortify the malignant progression of tumor cells, priming them for invasion and metastasis. Here, we provide an overview of the current knowledge on the composition of the inflammatory tumor microenvironment, with an emphasis on the major signals and signal-transducing events mediating different aspects of stromal cell-tumor cell communication that ultimately lead to malignant progression.

Progress and Challenges of Predictive Biomarkers for Immune Checkpoint Blockade

Over the past decade, immune checkpoint blockade (ICB) therapy has revolutionized the outlook for oncology with significant and sustained improvement in the overall patient survival. Unlike traditional cancer therapies, which target the cancer cells directly, ICB acts on the immune system to enhance anti-tumoral immunity. However, the response rate is still far from satisfactory and most patients are refractory to such treatment. Unfortunately, the mechanisms underlying such heterogeneous responses between patients to ICB therapy remain unclear. In addition, escalating costs of cancer care and unnecessary immune-related adverse events also are pertinent considerations with applications of ICB. Given these issues, identifying explicit predictive biomarkers for patient selection is an urgent unmet need to increase the efficacy of ICB therapy. The markers can be classified as tumor related and non-tumor-related biomarkers. Although substantial efforts have been put into investigating various biomarkers, none of them has been found to be sufficient for effectively stratifying patients who may benefit from immunotherapy. The present write up is an attempt to review the various emerging clinically relevant biomarkers affecting the efficacy of immune checkpoint inhibitors, as well as the limitations associated with their clinical application.