The scale of neutrophil involvement in cancer is staggering. Neutrophils are the most numerous circulating leukocytes in humans, produced at a rate of roughly one hundred billion cells per day in the bone marrow, and they can constitute the dominant immune population within many solid tumors. Large-scale analyses of the tumor immune landscape across human cancers have repeatedly found that high intratumoral neutrophil content correlates with poor prognosis in numerous malignancies, including renal cell carcinoma, head and neck cancer and non-small cell lung cancer. The neutrophil-to-lymphocyte ratio, a simple blood measurement, has emerged as one of the most robust prognostic biomarkers in oncology, predicting outcomes across tumor types and even forecasting response to immune checkpoint inhibitors.

Why would the immune system’s first responders become cancer’s accomplices? The answer, the review argues, lies in the extraordinary plasticity of neutrophils and their exquisite sensitivity to environmental cues. Tumors are, in the words of a classic 1986 observation by Harold Dvorak, wounds that do not heal, and neutrophils are the cells that respond to wounds. Cancers exploit the same inflammatory programs that neutrophils deploy during tissue repair. Tumor-derived signals such as granulocyte colony-stimulating factor, transforming growth factor-beta, interleukin-8 and other chemokines reprogram both the production and the function of neutrophils, driving emergency granulopoiesis in the bone marrow and recruiting immature, immunosuppressive granulocytes into the circulation and the tumor bed.

Once inside the tumor microenvironment, neutrophils promote cancer through several mechanistically distinct pathways. They release vascular endothelial growth factor and, critically, matrix metalloproteinase-9, an enzyme that liberates sequestered VEGF from the extracellular matrix and triggers the angiogenic switch that transforms a dormant lesion into a growing tumor. Studies in mouse models of multistage carcinogenesis showed that infiltrating neutrophils mediate this initial angiogenic switch, and human neutrophils are unique in releasing MMP-9 free of its natural inhibitor TIMP-1, making it an especially potent driver of new blood vessel formation. Neutrophil elastase, another granule protease, can degrade insulin receptor substrate-1 in tumor cells to accelerate lung tumor growth, and myeloid cell-derived reactive oxygen species have been shown to induce mutagenesis in adjacent epithelial cells, directly fueling the genomic instability that drives malignant transformation.

Perhaps no neutrophil behavior has attracted more attention in recent years than the formation of neutrophil extracellular traps, or NETs. First described in 2004 as web-like structures of DNA, histones and granule proteins that ensnare bacteria, NETs have since been implicated in a remarkable range of tumor-promoting processes. Recent work published in Nature demonstrated that NETs drive vascular occlusion, tumor necrosis and metastasis, linking phenomena long thought to be independent. NETs can sequester circulating tumor cells, shielding them from cytotoxic lymphocytes and natural killer cells; NET-associated DNA can bind the receptor CCDC25 on cancer cells, directing their migration; and NETs produced during systemic inflammation can awaken dormant cancer cells, triggering metastatic relapse years after primary tumor removal. Strikingly, the metastatic spread of breast cancer has been shown to accelerate during sleep, when rhythmic fluctuations in circulating neutrophils and cancer cell dynamics converge.

Neutrophils also construct the pre-metastatic niche, the distant soil that primary tumors prepare to receive their disseminated seeds. Tumor-derived factors mobilize neutrophils and their progenitors to future metastatic sites, where they suppress natural killer cell activity, remodel the extracellular matrix and create an immunologically permissive environment. In breast cancer models, neutrophils support the lung colonization of metastasis-initiating cells, and chronic stress has been shown to increase metastasis through neutrophil-mediated changes to the microenvironment. Even glucocorticoids, widely used clinically, can promote breast cancer metastasis by acting on these cells. The circadian biology of neutrophils, governed by an intrinsic molecular timer that coordinates immune defense and vascular protection, adds another layer of complexity to how and when these cells enable metastatic spread.

Yet the story is emphatically not one-directional. The review devotes substantial attention to the antitumor capacities of neutrophils, which many of the same molecules can mediate depending on context. Neutrophil elastase, which promotes tumor growth in some settings, has been shown in other contexts to selectively kill cancer cells and attenuate tumorigenesis, with important differences between mouse and human neutrophils in the production of its inhibitor, secretory leukocyte proteinase inhibitor. Activated neutrophils exert direct cytotoxicity against melanoma cells through reactive oxygen species, and tumor-associated neutrophils in early-stage human lung cancer can stimulate T cell responses rather than suppress them. Tumor-entrained neutrophils have even been shown to inhibit metastatic seeding in the lung, providing early evidence of spontaneous antimetastatic function. The pro- versus antitumor polarization of neutrophils, famously framed as N1 versus N2 states, is now understood to reflect a continuum of environmentally determined functional states rather than fixed identities.

This dual nature is precisely what makes neutrophils such compelling therapeutic targets. The review highlights several promising strategies. Neutrophil-activating therapy, developed by the Stanford group, demonstrated that pharmacologically activated neutrophils can eradicate tumors and reduce metastases independently of adaptive immunity. CD40 agonist antibodies recruit a subset of neutrophils associated with tumor control, and T cell immunotherapies have been shown to engage neutrophils to eliminate antigen-escape variants that would otherwise survive checkpoint blockade. Bacille Calmette-Guerin, the century-old tuberculosis vaccine used to treat bladder cancer, works in part by reprogramming hematopoiesis so that neutrophils develop the capacity to attack tumor cells, and interferon-gamma induces NET formation with tumor-killing activity in colorectal cancer. On the inhibitory side, CXCR2 antagonists, peptidyl arginine deiminase 4 inhibitors that block NET formation, arginase inhibitors, and antibodies that block the NET-associated immunosuppressive enzyme arginase-1 are all in clinical development, several in combination with checkpoint inhibitors.

Antibody-based approaches represent another frontier. Neutrophils are extraordinarily potent mediators of antibody-dependent cellular cytotoxicity, and IgA antibodies in particular trigger superior neutrophil-mediated killing of cancer cells compared with conventional IgG, engaging the Fc-alpha receptor to produce vigorous respiratory bursts and trogoptosis, a process in which neutrophils progressively strip membrane fragments from antibody-coated targets. Combining IgA-based therapeutics with blockade of the CD47-SIRP-alpha innate immune checkpoint, which prevents phagocytosis, has shown enhanced neutrophil cytotoxicity against neuroblastoma and other malignancies. Even more ambitiously, researchers have engineered chimeric antigen receptor neutrophils derived from induced pluripotent stem cells, which possess potent activity against solid tumors and can serve as delivery vehicles for tumor-microenvironment-responsive nanodrugs in glioblastoma. Neutrophils bearing adhesive polymer micropatches have been proposed as a drug-free immunotherapy platform.

The authors caution that translating these findings into the clinic requires resolving fundamental questions about neutrophil heterogeneity, nomenclature and species differences. A consensus statement has established standards for myeloid-derived suppressor cell classification, and recent single-cell atlases have mapped neutrophil developmental trajectories across tissues and disease states, revealing that mature and immature neutrophils converge on similar transcriptional signatures within tumors. Human and mouse neutrophils differ in important ways, including their circadian rhythms, granule composition and lifespan, with human neutrophils surviving approximately five days rather than hours as once believed. Nevertheless, the convergence of mechanistic insight, biomarker validation and early clinical activity suggests that the field has reached an inflection point. Neutrophils, long dismissed as terminally differentiated foot soldiers, are now recognized as master regulators of the tumor ecosystem, and learning to command them, rather than simply deplete them, may define the next era of cancer immunotherapy.

Subject of Research: The roles of neutrophils in tumor progression, immunosuppression, metastasis and cancer therapy

Article Title: Neutrophils in cancer

Article References: Diehl, M. I., Basto, P. A., Abikenari, M. A., Linde, I. L., Okwan-Duodu, D., & Engleman, E. G. (2026). Neutrophils in cancer. Nature Reviews Cancer. https://doi.org/10.1038/s41568-026-00968-2

Image Credits: AI Generated

DOI: 10.1038/s41568-026-00968-2

Keywords: neutrophils, cancer, tumor microenvironment, neutrophil extracellular traps, metastasis, immunosuppression, angiogenesis, tumor-associated neutrophils, immunotherapy, myeloid-derived suppressor cells, NETosis, granulopoiesis

The mechanistic heart of the review is the positive feedback loop it describes between cancer cells, tumor-associated neutrophils and NETs. Tumor cells orchestrate the reprogramming of neutrophils through paracrine signaling: they secrete chemokines such as CXCL1 and CXCL2, which recruit neutrophils via the CXCR1 and CXCR2 receptors, and cytokines including IL-1β, IL-8, granulocyte colony-stimulating factor and tumor-derived exosomes carrying mutant KRAS. Once in the tumor microenvironment, these neutrophils can be pushed toward NET formation by hypoxia, acidity, collagen signaling through DDR1, and stromal inputs from cancer-associated fibroblasts. The NETs themselves then feed back on the tumor, activating pro-growth pathways such as ERK and NF-κB, promoting epithelial-mesenchymal transition and reinforcing the very signals that recruit more neutrophils. This self-amplifying circuit explains why circulating and tumor-infiltrating NETs correlate so consistently with advanced disease in breast, pancreatic, gastric, colorectal and hepatocellular cancers, among others studied to date.

At the molecular level, NET formation, or NETosis, is a carefully choreographed demolition of the neutrophil’s own architecture. In the classical suicidal pathway, signaling through reactive oxygen species generated by the NADPH oxidase complex activates protein arginine deiminase 4, or PAD4, an enzyme that hypercitrullinates histone H3. Citrullination loosens the electrostatic grip of histones on DNA, driving chromatin decondensation, nuclear envelope breakdown and ultimately the explosive extrusion of decondensed DNA decorated with granule proteins. Neutrophil elastase and myeloperoxidase translocate to the nucleus to assist this dismantling, while cathepsin G and proteinase 3 join the final trap. Alternative routes exist as well: viable neutrophils can expel mitochondrial DNA to form traps without dying, and rapid, nuclear-based release has been documented within minutes of certain bacterial encounters. Which pathway dominates appears to depend on the stimulus, a specificity confirmed by comparative proteomic analyses showing that NETs induced by different triggers carry distinct protein cargoes.

As weapons of metastasis, NETs act on several fronts simultaneously. Their DNA scaffolds physically enmesh circulating tumor cells in the bloodstream, increasing adhesion to the vascular endothelium and creating a protective nidus in which disseminated cells can extravasate and colonize distant organs. Proteases embedded in the traps, notably matrix metalloproteinase-9 and neutrophil elastase, remodel the extracellular matrix and, in pancreatic cancer, activate quiescent stellate cells and cancer-associated fibroblasts that prepare fertile ground for micrometastases. Landmark work in mice showed that NETs produced during inflammation can rouse dormant cancer cells, explaining recurrences years after primary tumor removal. The traps also subvert immunity directly: NET-associated DNA can bind TMCO6 on T cells to impair CD8-positive cytotoxic function, upregulate the immunosuppressive enzyme CD73, decorate themselves with PD-L1, promote T cell exhaustion and foster T regulatory cell infiltration. In this sense, NETs function as both physical scaffolds for spread and chemical camouflage against the immune system, a dual role that the review identifies as central to immune evasion and distant metastasis.

The consequences extend to treatment resistance, one of oncology’s most stubborn bottlenecks. NETs generated during chemotherapy confer resistance by activating latent TGF-β, while the dense DNA matrix limits the diffusion of drugs such as doxorubicin, blunting its ability to trigger apoptosis in ovarian cancer cells. In bladder cancer, NETs contribute to radiation resistance, and low-dose ionizing radiation itself can provoke NET extrusion, an unsettling feedback. Immune checkpoint blockade suffers too: NET formation driven by IL-17 signaling mediates resistance in pancreatic cancer, cirrhotic extracellular matrix initiates immunosuppressive NETs that attenuate anti-PD-1 responses in hepatocellular carcinoma, and IGF2BP3-induced NETosis undermines oncolytic virotherapy in malignant glioma. Conversely, the review emphasizes that targeted disruption of the NET axis reverses these resistances and sensitizes tumors to radiotherapy, chemotherapy and checkpoint inhibitors, positioning NETs as genuinely novel therapeutic targets rather than mere biomarkers of misfortune.

A notable theme of the review is the breadth of candidate drugs capable of disarming the NET machinery, many of them repurposed from other fields. Anthracyclines suppress both NADPH oxidase-dependent and -independent NETosis; the antiparasitic ivermectin abrogates NETs and prevents melanoma metastasis in preclinical models; chloroquine and hydroxychloroquine reduce trap formation partly by inhibiting PAD4; and the glucagon-like peptide-1 receptor agonists liraglutide and exenatide enhance checkpoint blockade efficacy by attenuating NETs in lung and liver cancers. Metformin mitigates obesity-driven NET-driven tumor aggressiveness in mice, the nuclear export inhibitor selinexor blocks human NET formation in vitro, and histidine-rich glycoprotein suppresses hepatic metastatic seeding. Even traditional Chinese medicine formulations, from Huang Qin Decoction to Pi Ji Pills, and phytochemicals such as kaempferol, resveratrol, epigallocatechin-3-gallate and emodin, have been shown to interfere with the ROS-PAD4, STAT3-CXCL8 and PI3K-AKT pathways that drive trap formation. Biomaterials approaches, including NET-degrading enzyme hydrogels applied after surgery, and localized photoregulated enzyme delivery, offer physically targeted ways to dismantle traps at metastatic sites.

Translating these discoveries into the clinic depends on measuring NETs reliably, and the review devotes substantial attention to detection technology. The most widely used circulating markers are cell-free DNA, nucleosomes, myeloperoxidase-DNA and neutrophil elastase-DNA complexes, and citrullinated histone H3, the latter quantified by increasingly refined enzyme-linked immunosorbent assays validated in human plasma. Flow cytometric assays allow direct enumeration of NET-bearing structures in blood, atomic force microscopy has resolved the physical architecture of individual traps, and microfluidic chips can capture chromatin fibers from a single drop of blood, while computational image-analysis algorithms now standardize histological quantification. Clinically, peripheral blood NET biomarkers have been associated with diagnosis and progression of malignant tumors, trap-associated CEACAM1 has been proposed as a therapeutic target in metastatic colon cancer, and PD-L1-positive neutrophils releasing NETs in malignant ascites show promise as a hepatocellular carcinoma biomarker. Gene-expression signatures built around NET-related genes and long non-coding RNAs predict prognosis and immunotherapy response across gastric, breast, colon, lung, head-and-neck and soft-tissue cancers, although the review cautions that inconsistent findings and tumor heterogeneity still constrain their deployment.

The prognostic potential is especially striking. Tumor-infiltrating NETs predict post-surgical survival in pancreatic ductal adenocarcinoma, blood NETosis correlates with progression in head and neck cancer, pan-cancer signatures built from NET-associated genes stratify patient outcomes, and a NET-score has emerged as a prognostic marker in colorectal cancer. NETs also influence cancer-associated thrombosis, a major cause of morbidity: tumor-derived exosomes induce NETs that establish hypercoagulability, and IL-1β blockade attenuates thrombosis in NET-dependent breast cancer models. Yet the review is candid about limitations. Detection technologies remain imperfect and poorly standardized, prognostic modeling must contend with heterogeneous patient populations, and some research findings conflict, reflecting context-dependent roles of neutrophil subsets that range from antitumor to pro-tumor. Aging itself alters NET biology, complicating extrapolation from young animal models to elderly patients. Future work, the authors argue, should prioritize optimizing detection methods, conducting rigorous clinical validation and identifying tumor-type-specific therapeutic targets.

The broader message is that the immune defense once celebrated for strangling microbes has become a central hub in cancer biology, one that links inflammation, dormancy, metastasis, thrombosis and treatment failure within a single mechanistic framework. By mapping the regulatory factors, from PAD4 and neutrophil elastase to CXCL chemokines and TGF-β, and by cataloguing both the pharmacological and biomaterial tools that can interrupt them, the review provides a theoretical basis for bringing NETs into precision oncology. If the technical and validation challenges can be overcome, clinicians may one day read a patient’s NET profile the way they now read hormone receptor status, and use NET-disrupting agents to prevent metastasis and sensitize tumors to the therapies already at hand. For now, the convergence of mechanistic insight, assay development and drug repurposing suggests that a web once woven for defense is becoming an actionable thread in the fight against cancer.

Subject of Research: Neutrophil extracellular traps in tumor progression, detection and diagnosis

Article Title: Neutrophil extracellular traps in tumor progression: from mechanistic insights and regulatory factors to clinical detection and diagnosis

Article References: Neutrophil extracellular traps in tumor progression: from mechanistic insights and regulatory factors to clinical detection and diagnosis. (n.d.). https://doi.org/10.1007/s00109-026-02709-2

Image Credits: AI Generated

DOI: 10.1007/s00109-026-02709-2

Keywords: neutrophil extracellular traps, tumor-associated neutrophils, metastasis, immune evasion, therapy resistance, PAD4, cancer biomarkers, tumor microenvironment, diagnosis, checkpoint blockade, NETosis, precision oncology

The research, led by Ruizhe Huang, Zhiyi Liu and Yawei Zhao under the correspondence of Siyu Chen at the Department of Medical Oncology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, was built on a strikingly broad computational foundation. The team integrated seven single-cell RNA-sequencing cohorts, two spatial transcriptomic cohorts, bulk RNA sequencing linked to patient survival data, CRISPR-based gene essentiality screens, and three independent immunotherapy cohorts. Rather than relying on any single analytical method, the investigators assembled a machine learning framework in which different algorithms handled different parts of the problem, each feeding its output into the next stage of analysis.

The first step involved unsupervised consensus non-negative matrix factorization, a mathematical technique that decomposes gene expression data into coherent transcriptional programs without any prior labeling. Applied to malignant cells across the cohorts, this approach resolved four distinct malignant meta-programs. One of these, designated MP3, carried a mixed mesenchymal and interferon signaling signature, suggesting tumor cells that had partially undergone epithelial–mesenchymal transition while simultaneously mounting inflammatory responses. Crucially, the researchers found that MP3 carried prognostic information only in the context of the other three programs. When considered in isolation, its signal was misleading; when modeled jointly, patients with higher MP3 activity relative to the other programs fared significantly worse, with a hazard ratio of 1.43 per standard deviation and a p-value of 0.0045.

That context-dependence led the team to construct a composite score, essentially the difference between standardized MP3 activity and the activity of a fourth program, MP4, which resembled healthy alveolar cells and was independently protective. This single composite metric, z(MP3) minus z(MP4), proved prognostic on its own, with a hazard ratio of 1.40 and a p-value of 3.4 multiplied by ten to the negative sixth power. The reciprocal balance between an aggressive, plastic mesenchymal state and a differentiated, alveolar-like state thus encoded clinically meaningful information that neither program revealed alone. It is a technical but important lesson: in tumors defined by cellular plasticity, the relative composition of transcriptional states, not the abundance of any one state, appears to determine patient outcomes.

Having established the malignant programs, the researchers turned to the immune microenvironment and deployed deep generative models to interrogate neutrophils. Using scVI and its supervised extension scANVI, probabilistic models designed to denoise single-cell data and transfer cell type labels across datasets, the team resolved distinct neutrophil states within the tumor microenvironment. What emerged was an OSM-primed neutrophil axis. OSM, or oncostatin M, is an inflammatory cytokine, and neutrophils primed with it appeared to participate in a signaling circuit alongside SPP1-positive macrophages, the very cell population that had dominated prior studies of mesenchymal transition in this cancer. The two cell types formed what the authors describe as a partitioned dual circuit, with neutrophils and macrophages occupying complementary roles in sustaining the mesenchymal niche.

What made this finding particularly compelling was its spatial validation. Single-cell data strips away geography, telling researchers which cells exist but not where they sit within the tumor. To recover that geometry, the team applied cell2location, a probabilistic deep learning method for spatial deconvolution that estimates which cell types and states occupy each spot in a spatial transcriptomics slide. They coupled this with random forest multi-view modeling to map communication fluxes between cell populations. The results showed that OSM signaling flux was directed primarily toward macrophages and fibroblasts rather than toward the malignant cells themselves, which means that any influence of the neutrophil circuit on tumor cells is likely indirect, mediated through the stromal and macrophage compartments. The two-compartment niche, pairing OSM-primed neutrophils with their macrophage and fibroblast partners, was reproducible across both spatial cohorts, strengthening confidence that it reflects genuine tumor architecture rather than computational artifact.

The final and perhaps most ambitious stage of the pipeline used Geneformer, a transformer-based single-cell foundation model pretrained on large corpora of gene expression data, to perform in silico gene deletion perturbations. In effect, the model simulates what happens to a cell’s transcriptional state when a particular gene is removed, allowing researchers to computationally screen candidate dependencies across the three coupled state transitions identified in the study: from alveolar-like to mesenchymal malignant states, and through the associated neutrophil and macrophage circuits. The screen converged on SEC61G, a gene encoding a component of the SEC61 translocon, the protein channel in the endoplasmic reticulum membrane through which secreted and membrane proteins pass as they are synthesized. Because mesenchymal tumor cells and inflammatory immune cells both rely heavily on protein secretion, a translocon dependency is biologically plausible.

The authors are notably careful about how they frame this nomination. SEC61G already had independent published support in lung adenocarcinoma, so the team treats it as a positive control re-derived de novo rather than a wholly new drug target. What they report as genuinely new is that SEC61G’s prognostic signal is independent of 7p11.2 copy number, the chromosomal region in which the gene resides and a region frequently amplified in this cancer. In other words, the poor outcomes associated with high SEC61G expression are not simply a reflection of having more copies of the gene, hinting at regulatory or functional dependencies that copy number analysis alone would miss. The overall survival hazard ratio for SEC61G was 1.64 with a p-value of 1.3 multiplied by ten to the negative sixth, and the gene showed higher expression in immunotherapy non-responders in two of the three checkpoint inhibitor cohorts examined, reaching statistical significance in one.

What elevates this study above a typical bioinformatics exercise is its insistence on orthogonal validation. The four-endpoint validation cascade required convergent evidence from survival analysis, immunotherapy response data, CRISPR essentiality screens, and the perturbation modeling itself before any candidate dependency was accepted. This design directly addresses one of the most persistent criticisms of single-cell oncology research: that computational nominations of drug targets often evaporate under experimental scrutiny. By demanding agreement across data types that share no common analytical machinery, the framework filters out candidates whose signals are artifacts of any single method or dataset. The result is a shorter but far more defensible list of candidate targets than a typical computational screen would produce.

The broader significance lies in the generalizability of the approach. The authors explicitly position their strategy, foundation model perturbation followed by multi-endpoint orthogonal validation, as a reusable template for nominating therapeutic targets in plasticity-driven solid tumors, a category that includes many of the hardest cancers to treat. As foundation models like Geneformer mature and spatial transcriptomic datasets accumulate, pipelines of this kind could compress the path from observational single-cell atlases to testable therapeutic hypotheses. For lung adenocarcinoma patients, the immediate deliverables are a newly mapped neutrophil-associated mesenchymal niche that reframes how the tumor microenvironment sustains aggressive cell states, and a candidate translocon dependency whose vulnerability can now be pursued with experimental tools. The work was funded by the National Natural Science Foundation of China and the Shanghai Committee of Science and Technology, and relied exclusively on publicly available, de-identified human data, meaning that its findings can be independently reanalyzed and challenged by any laboratory with computational resources and internet access.

Subject of Research: Deep learning integration of single-cell and spatial transcriptomics to map a neutrophil-associated mesenchymal niche and identify candidate tumor dependencies in lung adenocarcinoma.

Article Title: Deep learning integration of single-cell and spatial transcriptomics reveals a neutrophil-associated mesenchymal niche and a candidate translocon dependency in lung adenocarcinoma

Article References: Deep learning integration of single-cell and spatial transcriptomics reveals a neutrophil-associated mesenchymal niche and a candidate translocon dependency in lung adenocarcinoma. (n.d.). https://doi.org/10.1007/s00262-026-04560-3

Image Credits: AI Generated

DOI: 10.1007/s00262-026-04560-3

Keywords: lung adenocarcinoma, single-cell RNA sequencing, spatial transcriptomics, tumor-associated neutrophils, epithelial–mesenchymal transition, SEC61G, deep learning, tumor microenvironment, Geneformer, immunotherapy response, OSM signaling, cancer prognosis

ARID1A encodes a component of the SWI/SNF, or BAF, chromatin-remodeling complex, a molecular machine that regulates access to DNA and helps determine which genes are active. Loss-of-function alterations in ARID1A can alter cellular identity, DNA repair, inflammatory signaling and interactions with the surrounding tissue. Although ARID1A deficiency is found in several cancer types, including pancreatic ductal adenocarcinoma, its biological consequences are not uniform. In pancreatic tumors, the loss of this gene appears to produce vulnerabilities that can be exploited therapeutically, while simultaneously contributing to a microenvironment that is unusually resistant to immune-based treatment. The new findings connect those two features through the CXCR2 signaling pathway, a chemokine receptor that acts as a navigational system for neutrophils and can also influence the behavior of malignant cells.

CXCR2 is activated by a group of inflammatory chemokines, including CXCL1, CXCL2, CXCL5 and CXCL8 in human systems. These signals create chemical trails that guide neutrophils from the bloodstream into tissues. In a tumor, however, the process can become distorted. Tumor-associated neutrophils may release proteases, reactive oxygen species, growth-promoting factors and immunosuppressive mediators. They can remodel the extracellular matrix, stimulate blood-vessel formation and interfere with the ability of cytotoxic T cells to enter or function within the tumor. By blocking CXCR2, researchers aim to interrupt the recruitment and activation of these neutrophils rather than eliminating the entire immune cell population. That distinction is important because neutrophils perform essential functions in normal host defense, and a clinically useful treatment would need to balance antitumor activity with preservation of immune protection.

The study’s central advance lies in its conclusion that CXCR2 inhibition acts on more than one cellular compartment. Anti-CXCR2 antibodies were associated with direct suppression of ARID1A-deficient tumor cells and with a reduction in the tumor-supportive influence of associated neutrophils. The tumor-cell effect suggests that cancer cells carrying ARID1A loss may depend on CXCR2-related signaling for survival, proliferation or adaptation to stress. The immune effect reflects a different mechanism: blocking the receptor can prevent neutrophils from accumulating in the tumor or can alter their functional state after arrival. Together, these actions may produce a stronger response than targeting either the malignant cells or the tumor microenvironment alone. The result is a therapeutic concept based on biological cooperation, in which the same antibody interferes with a cancer-intrinsic pathway and an immune-extrinsic support system.

This dual mechanism is particularly relevant to pancreatic ductal adenocarcinoma, whose dense stroma and suppressive immune landscape have repeatedly limited the impact of immunotherapy. Many pancreatic tumors contain abundant fibroblasts, extracellular matrix proteins, suppressive myeloid cells and relatively few T cells capable of recognizing and killing cancer cells. Even when T cells are present, they may be physically excluded from tumor nests or functionally silenced by cytokines, metabolic stress and inhibitory receptor signaling. Neutrophils can contribute to this barrier by shaping the tissue architecture and producing factors that restrain adaptive immunity. Removing or redirecting that pressure could make the tumor more accessible to therapeutic T-cell responses. The research therefore treats CXCR2 not simply as a marker of inflammation, but as a control point linking tumor behavior, immune-cell trafficking and the effectiveness of immune checkpoint blockade.

In experimental models, anti-CXCR2 treatment reduced the growth of ARID1A-deficient pancreatic tumors. The effect became more pronounced when the antibody was combined with immunotherapy, indicating that CXCR2 blockade may help convert an immune-resistant tumor into one that is more responsive to T-cell-directed treatment. Although the precise combination used depends on the experimental system, the underlying logic is consistent with current immuno-oncology strategies: suppress the signals that recruit or empower immunosuppressive myeloid cells while releasing inhibitory brakes on antitumor lymphocytes. A checkpoint inhibitor alone may fail if neutrophils continue to exclude T cells or suppress their activity. Conversely, disrupting neutrophil trafficking may be insufficient if tumor-reactive T cells remain inhibited. The combined approach addresses both limitations, creating conditions in which immune activation can be translated into tumor-cell killing.

The research also highlights the importance of genotype-guided treatment. ARID1A deficiency is not merely a descriptive feature of the cancer; it may determine how the tumor responds to CXCR2-directed therapy. Tumors with intact ARID1A could rely on different signaling networks and may not display the same dependence on CXCR2. This raises the possibility that ARID1A status could serve as a biomarker for selecting patients most likely to benefit. In a future clinical setting, testing might involve sequencing tumor tissue or circulating tumor DNA to identify damaging ARID1A alterations, followed by assessment of CXCR2 activity and neutrophil infiltration. Such a strategy would require careful validation because gene loss can be heterogeneous within a tumor, and the presence of an ARID1A mutation does not automatically prove that every malignant cell has the same biological dependency.

The findings nevertheless remain preclinical, and several challenges must be addressed before they can influence routine care. Antibodies that block CXCR2 could affect neutrophil movement outside tumors, potentially increasing susceptibility to infection or altering wound healing and inflammatory responses. Tumors may also bypass the blockade by using alternative chemokine receptors or by recruiting other suppressive myeloid populations, including monocytes and macrophages. The balance between suppressing harmful tumor-associated neutrophils and preserving protective neutrophil functions will be a central issue in dose selection and patient monitoring. Researchers will also need to determine whether the treatment is most effective before surgery, after surgery, in metastatic disease or in combination with chemotherapy, radiation or targeted drugs. Pancreatic tumors are biologically diverse, and responses observed in mouse models may not fully capture the complexity of human disease.

The study’s implications extend beyond pancreatic cancer because ARID1A alterations and CXCR2-driven inflammation occur in multiple malignancies. If the relationship between chromatin-remodeling defects and neutrophil-dependent immune suppression is confirmed in other tumor types, CXCR2 antibodies could become part of a broader precision-immunotherapy framework. The work also reinforces a growing view of cancer genetics: mutations do not only change the behavior of tumor cells in isolation; they can reshape the immune ecosystem surrounding them. A defect in chromatin regulation may alter the signals that cancer cells emit, the immune cells they attract and the conditions that determine whether therapy succeeds. By targeting that network rather than focusing exclusively on the malignant cell, investigators may be able to expose vulnerabilities that conventional treatments leave untouched.

For patients with pancreatic cancer, the prospect of a therapy tailored to ARID1A deficiency remains preliminary but significant. The new findings suggest that blocking CXCR2 could strike at the disease from two directions, weakening the tumor itself and removing a myeloid shield that limits immune attack. The enhanced response to immunotherapy provides a rationale for future studies testing CXCR2 inhibition alongside checkpoint blockade in carefully selected patients. Those trials will need to establish safety, define reliable biomarkers, measure changes in neutrophil populations and determine whether tumor shrinkage translates into longer survival. If the results hold in humans, the approach could offer a way to transform the inflammatory environment of ARID1A-deficient pancreatic tumors from an obstacle into a therapeutic target, bringing precision medicine and immunotherapy closer together for one of the world’s most formidable cancers.

Subject of Research: ARID1A-deficient pancreatic cancer and CXCR2-targeted immunotherapy

Article Title: Dual inhibition of tumor cells and tumor-associated neutrophils by anti-CXCR2 antibodies suppresses tumor growth and augments immunotherapy efficacy in ARID1A-deficient pancreatic cancer

Image Credits: AI Generated

Keywords: pancreatic cancer, ARID1A deficiency, CXCR2, tumor-associated neutrophils, immunotherapy, immune checkpoint blockade, tumor microenvironment, precision oncology, chemokine signaling, pancreatic ductal adenocarcinoma

Led by immuno-oncology expert Mikaël Pittet, the team overcame these hurdles by developing a sophisticated probability classifier capable of parsing neutrophil functional states from raw sequencing data, thus exposing a conserved and terminally differentiated neutrophil population characterized by high expression of the chemokine CCL3. This discovery suggests that tumors actively reprogram neutrophils, guiding them through a dynamic maturation trajectory culminating in a senescent, CCL3^hi phenotype that thrives within hypoxic niches of the TME. These specialized neutrophils engage genetic subroutines that equip them to withstand harsh microenvironmental conditions, while simultaneously promoting tumor cell survival and growth.

The team’s integrative approach, spanning over 190 tumor samples across both human and murine models, confirmed that this CCL3^hi TAN subset is ubiquitous across multiple cancer types. Crucially, CCL3 does not merely serve as a marker; it functionally propels neutrophils down their terminal maturation pathway by binding to its receptor CCR1 on neutrophil surfaces. This signaling axis bolsters neutrophil survival in oxygen-deprived tumor regions and activates gene networks that underwrite tumor progression. Mouse models deficient in either neutrophil-derived CCL3 or CCR1 exhibited impaired tumor growth, unequivocally demonstrating the axis’s critical role in fostering a pro-tumor microenvironment.

This work highlights an elegant molecular mechanism whereby tumors sustain a pro-cancer immune niche through manipulation of neutrophil biology. The identification of CCL3 and its receptor CCR1 as key drivers of neutrophil-mediated tumor progression complicates the classical view of neutrophils simply as anti-pathogen effectors, revealing an insidious adaptation exploited by cancer cells. Moreover, the conserved nature of the CCL3^hi state across species and tumor types positions this axis as a promising target for therapeutic intervention, potentially enabling disruption of the pro-tumor neutrophil compartment to stymie cancer development.

The findings dovetail with previous research from Pittet’s group, which unveiled prognostic paradigms based on macrophage gene expression ratios—specifically, the CXCL9-to-SPP1 ratio—as broad predictors of cancer outcomes. The newly discovered CCL3^hi TANs emerge as a second, independent prognostic variable that could refine patient stratification and influence clinical decision-making. While macrophage-related signatures reflect an anti- versus pro-tumor dichotomy, the CCL3^hi neutrophil program provides a complementary axis reflecting neutrophil maturation and tumor-promoting capacities.

Biologically, the study sheds light on why neutrophils have been a vexing subject in cancer immunology. Their notoriously low RNA content and rapid turnover have hindered deeper phenotyping via single-cell transcriptomics, but the computational innovation introduced by Pittet’s team circumvents this limitation by probabilistic inference of transcriptional states, opening new vistas for exploring neutrophil heterogeneity. This approach not only facilitates mechanistic insights but also primes the field for the development of biomarkers that may predict disease trajectories or responses to emerging immunotherapies.

Mechanistic experiments further delineated the role of CCL3/CCR1 signaling in enabling neutrophils to adapt to hypoxia, a hallmark of solid tumors. In these oxygen-deprived regions, tumor cells and immune infiltrates orchestrate complex interactions that dictate progression or regression. By promoting neutrophil survival and terminal maturation within these niches, CCL3 sustains a feed-forward loop enhancing tumor resilience. This pervasive biological axis underscores the importance of considering microenvironmental context when designing strategies to modulate immune cell function in cancer.

From a clinical vantage point, targeting CCL3^hi TANs represents an innovative therapeutic frontier. Unlike current approaches that broadly deplete neutrophils—often leading to detrimental side effects—finely tuning the maturation trajectory or interrupting CCR1 signaling could selectively disarm the pro-tumor subset without compromising innate immunity. Such precision immunomodulation aligns with the contemporary paradigm shift toward harnessing tumor immunity with minimal collateral damage, promising more efficacious and tolerable cancer treatments.

In addition to its translational implications, this research advances fundamental immunology by illuminating how tumors co-opt neutrophil biology, inducing senescence-like programs that paradoxically support malignancy. The integrative, multi-omic approach combining computational deconvolution, functional assays, and murine genetics serves as a blueprint for dissecting complex cellular states in dynamic environments. As immune profiling technologies evolve, a more nuanced understanding of TAN diversity and plasticity will emerge, guiding next-generation immunotherapies.

In sum, the identification of CCL3^hi tumor-associated neutrophils and their central role in tumor growth marks a transformative advance in cancer immunology. This work not only illuminates a heretofore hidden dimension of the TME but also provides tangible molecular targets for disrupting the vicious cycle of tumor-immune interactions that fuel malignancy. As the research community builds upon these insights, the prospect of therapeutically reprogramming the TME to favor anti-tumor immunity appears increasingly attainable, heralding a new chapter in the war against cancer.

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Subject of Research: Tumor-associated neutrophils and their role in cancer progression through the CCL3/CCR1 signaling axis.

Article Title: Tumors Harness CCL3-Expressing Neutrophils as a Driver of Cancer Progression in Diverse Cancers

News Publication Date: February 5, 2026

Web References:
– https://www.ludwigcancerresearch.org/scientist/mikael-pittet/
– https://www.cell.com/cancer-cell/fulltext/S1535-6108(26)00045-0
– https://www.ludwigcancerresearch.org/news-releases/ludwig-lausanne-study-illuminates-a-potentially-exploitable-coordination-of-gene-expression-across-the-tumor-microenvironment/
– https://www.science.org/doi/10.1126/science.ade2292

Image Credits: Ludwig Cancer Research

Keywords: Cancer, Tumor Microenvironment, Neutrophils, Tumor-Associated Neutrophils, CCL3, CCR1, Gene Expression, Immuno-oncology, Hypoxia, Single-Cell RNA Sequencing, Computational Biology, Biomarkers