Brain metastases (BrMs) occur in approximately 30% of cancer patients, causing nearly one-fifth of cancer deaths. While immune checkpoint inhibitors (ICIs) benefit some BrM patients, responses remain highlyvariable. This variability partly reflects distinct histopathological growth patterns that include minimally invasive (MI) and highly invasive (HI) brain BrMs. Here we show that MI BrMs exhibit robust immune infiltration, whereas HI lesions are immunosuppressed. However, histological differentiation between MI and HI can be challenging because of subjective margin assessment. Here, using highly multiplexed spatial proteomics on 119 tumor sections from 46 patients with BrMs, we identify CHI3L1 as a key mediator of the immunosuppressive microenvironment in HI BrMs. In preclinical models, genetic deletion of CHI3L1 converts immune-cold metastases into lymphocyte-rich, ICI-responsive lesions infiltrated by granzyme B+CD8+ T cells. In BrM patients treated with ICI, immunohistochemical quantification of CHI3L1 expression was a stronger predictor of ICI response than traditional MI/HI classification. Thus, CHI3L1 represents a promising biomarker and therapeutic target for BrMs.

Physiological host factors, such as the gut microbiome and obesity, independently influence anti-tumour immunity and responses to immune checkpoint inhibitors (ICIs)1, with high body mass index (BMI) having an unexpected link with greater ICI efficacy2-6. However, how these factors interact across diverse dietary contexts remains unclear. Here, using 12 mouse diet models that reflect a spectrum of obesity biology, we characterize diet-driven metabolic, immune and gut microbiota features associated with ICI sensitivity. We find that obesity-associated ICI responses are poorly correlated with metabolic dysfunction and are instead dependent on the diet-gut axis. Obesogenic diets promote a robust and persistent gut microbial ecosystem that is capable of restoring ICI sensitivity following a short-term diet switch or fecal microbiota transplants (FMTs) from non-responder models. Monocolonization of germ-free mice with favourable bacteria such as Lactobacillus johnsonii, together with an obesogenic diet, synergistically promotes tumour regression through an enrichment of microbiota-derived aromatic amino acid metabolites. Moreover, human-to-mouse FMT from donors with a high BMI enhanced ICI efficacy compared with donors with a normal BMI, and an obesogenic diet restored sensitivity following FMT from a non-responder patient. Our study provides insight on epidemiological associations between BMI and ICI efficacy, and suggests that immunomodulatory synergy between diet and the gut microbiota could be leveraged to improve ICI outcomes and FMT interventions.

Lung adenocarcinoma (LUAD) is a molecularly diverse form of lung cancer characterized by distinct oncogenic driver mutations that influence both tumour biology and clinical outcomes. Understanding the interplay between these oncogenic drivers and the tumour microenvironment (TME) is crucial for improving therapeutic strategies and patient management. Here, we investigate the impact of driver mutations on the composition and spatial architecture of the TME in LUAD. Using imaging mass cytometry (IMC), we analyse tumour samples from 157 LUAD patients, integrating genomic and clinical data to link specific mutations with tumour characteristics. Unique patterns are associated with mutated KRAS and EGFR tumours with TP53 co-mutations, suggesting these co-mutations reshape the TME and promote resistance to tyrosine kinase inhibitors (TKIs). Overall, our findings highlight the complex interplay between oncogenic driver mutations and the TME in LUAD, underscoring the importance of integrating genomic and cellular data to understand the underlying tumour behaviour and prognosis.

OBJECTIVE:Uncontrolled pain remains a major clinical challenge in the management of knee osteoarthritis (OA), the most common disabling joint disease. Worse pain is associated with synovial innate immune cell infiltration (synovitis), but the role of innate immune-regulatory cells in pain is unknown. Our objective was to identify synovial innate immune cell subsets and pathophysiologic mechanisms associated with worse pain in patients with knee OA. METHODS:Synovial tissue biopsies from 122 patients with mild-to-severe knee OA pain (Knee Injury and OA Outcome Score [KOOS]) were analyzed to identify associations between synovial histopathology and worse pain. We then used spatial transcriptomics and proteomics of synovial tissue microenvironments (n = 32), followed by single-cell RNA sequencing (n = 8), to identify synovial cell composition and cell-cell communication networks in patients with more severe OA pain. RESULTS:Histopathological signs of synovial microvascular dysfunction and perivascular edema were associated with worse KOOS pain (-10.76; 95% confidence interval [CI] -18.90 to -2.61). Patients with worse pain had fewer immune-regulatory macrophages, expanded fibroblast subsets, and enrichment in neurovascular remodeling pathways. Synovial macrophages from patients with worse pain expressed markers of immune exhaustion and decreased phagocytic function (-19.42%; 95% CI -35.96 to -2.89) and their conditioned media increased neuronal cell stress in dorsal root ganglia. CONCLUSION:Although synovitis increases during OA, our findings suggest that exhaustion, dysfunction, and loss of immune-regulatory macrophages is associated with worse pain and may be an important therapeutic target.

Lung cancer is the leading cause of cancer-related deaths. An enhanced understanding of the immune microenvironments within these tumours may foster more precise and efficient treatment, particularly for immune-targeted therapies. The spatial architectural differences between lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) are relatively unexplored. Here, we applied imaging mass cytometry to a balanced cohort of LUAD and LUSC patients, matched for clinical factors such as age, sex, and smoking history, to analyze 204 histopathology images of tumours from 102 individuals with non-small cell lung cancer (NSCLC). By analyzing interactions and broader cellular networks, we interrogate the tumour microenvironment to understand how immune cells are spatially organized in clinically matched adenocarcinoma and squamous cell carcinoma subsets. This spatial analysis revealed distinct patterns of immune cell aggregation, particularly among macrophage populations, that correlated with patient prognosis differentially in adenocarcinoma and squamous cell carcinoma, suggesting potential new strategies for therapeutic intervention. Our findings underscore the importance of analyzing NSCLC histological subtypes separately when investigating the spatial immune landscape, as microenvironmental characteristics and cellular interactions differed by subtype. Recognizing these distinctions is essential for designing precision therapies tailored to each subtype’s unique immune architecture, ultimately enhancing patient outcomes. The spatial architecture of the lung cancer microenvironment could influence the survival outlook and therapeutic options of patients. Here the authors find distinct patterns and composition of immune cells when comparing lung adenocarcinomas and lung squamous cell carcinomas, paving way for precision immune therapy according to histological subtype.

Neutrophils exhibit remarkable phenotypic and functional diversity across tissues and diseases1,2, yet the lack of understanding of how this immune compartment is globally organized challenges translation to the clinic. Here we performed single-cell transcriptional profiling of neutrophils spanning 47 anatomical, physiological and pathological scenarios to generate an integrated map of the global neutrophil compartment in mice, which we refer to as NeuMap. NeuMap integrates and expands existing models3,4 to generate fundamental new insights; it reveals that neutrophils organize in a finite number of functional hubs that distribute sequentially during maturation to then branch out into interferon-responsive and immunosuppressive states, as well as a functionally silent state that dominates in the healthy circulation. Computational modelling and timestamp analyses identify prototypical trajectories that connect these hubs, and reveal that the dynamics and preferred paths vary during health, inflammation and cancer. We show that TGFβ, IFNβ and GM-CSF push neutrophils along the different trajectories, and projection of chromatin accessibility sites onto NeuMap reveals that the transcription factor JUNB controls angiogenic and immunosuppressive states and promotes tissue revascularization. The architecture of NeuMap appears to be conserved across sex, environmental and genetic backgrounds, as well as in humans. Finally, we show that NeuMap enables inference of the pathophysiological state of the host by profiling blood neutrophils. Our study delineates the global architecture of the neutrophil compartment and establishes a framework for exploration and exploitation of neutrophil biology.

List of common direct target genes of BRD4 in KRAS-mutant NSCLC cells.

List of BRD4 binding regions on gene loci related to cell cycle.

Spatial proteomics has transformed cancer research by providing unparalleled insights into the microenvironmental landscape of tumors. Here we discuss how these technologies have significantly advanced our understanding of cell–cell interactions, tissue organization and spatially coordinated mechanisms underlying antitumor immune responses, and will pave the way for emerging breakthroughs in cancer research.

Abstract The tumor immune microenvironment (TIME) is a critical determinant of therapeutic response. However, the mechanisms regulating its modulation are not fully understood. HER216, an oncogenic splice variant of the human epidermal growth factor receptor (HER2), has been implicated in breast cancer and other tumor types as a driver of tumorigenesis and metastasis. Nevertheless, the underlying mechanisms of HER2Δ16-mediated oncogenicity remain poorly understood. Here, we show that HER2∆16 expression is not exclusive to the clinically HER2+ subtype and associates with a poor clinical outcome in breast cancer. To understand how HER2 variants modulated the tumor microenvironment, we generated transgenic mouse models expressing either proto-oncogenic HER2 or HER2∆16 in the mammary epithelium. We found that HER2∆16 tumors were immune cold, characterized by low immune infiltrate and an altered cytokine profile. Using an epithelial cell surface proteomic approach, we identified ENPP1 (ectonucleotide pyrophosphatase/phosphodiesterase 1) as a functional regulator of the immune cold microenvironment. We generated a knock-in model of HER2Δ16 under the endogenous promoter to understand the role of Enpp1 in aggressive HER2+ breast cancer. Knockdown of Enpp1 in HER2Δ16-derived tumor cells resulted in decreased tumor growth, which correlated with increased T-cell infiltration. These findings suggest that HER2Δ16-dependent Enpp1 activation associates with aggressive HER2+ breast cancer through its immune modulatory function. Our study provides a better understanding of the mechanisms underlying HER2Δ16-mediated oncogenicity and highlights ENPP1 as a potential therapeutic target in aggressive HER2+ breast cancer.

List of NSCLC cell lines with corresponding BRD4 mRNA levels and IC50 values for palbociclib.

e21517 Background: Up to 60% of metastatic melanoma patients develop brain metastases, and 5% develop leptomeningeal disease (LD), which presents with the worst prognosis of any melanoma brain metastasis (MBM) infiltration pattern. Median survival duration for MBM is ~12 months, however for LD patients it can be < 10 weeks. The spatial immune landscape of MBM with and without LD remains poorly understood. Methods: To spatially characterize the tumor microenvironment (TME) of MBM, we performed CyTOF Imaging Mass Cytometry (CyTOF-IMC) on a highly multiplexed panel of 35 antibodies for 21 MBMs (13 with LD, 8 without LD). We performed a novel cell segmentation, cell type assignment and identification approach to identify cell lineages to spatially characterize the TME of MBMs, segmenting and classifying 130,000 cells into 19 cell types. Results: We found enrichment of dendritic cells in the direct neighbourhood of melanoma cells of patients with LD (p = 0.019) and trends towards elevation of anti-tumoral monocyte populations in the TME of patients without LD. To investigate survival outcomes, we divided our cohort into long (≥365days) and short-survivors ( < 365 days), and found significant elevation of anti-tumoral T-cell populations (Total T-cells, CD8+ T-cells, CD4+ T-cells and CD3+CD4-CD8- T-cells, p < 0.05), and closer proximity of T-cells (CD8+ & CD4+ T-cells) to melanoma cells (p < 0.05). Survival analysis using median cell-proportion for each T-cell subset showed statistically significant (p < 0.05) survival differences between patients with high and low cell-proportions of CD8+ T-cells and CD4+ T-cells, with similar trends observed for a subset of patients (n = 13) with LD and a subset of patients treated with ICIs (n = 10), and results were confirmed by a Cox Regression Model. Cellular neighborhood (CN) analysis was performed generating N = 12 stable CNs. We found patients with higher proportions of CN9 (M1-like-microglia/M2-like-microglia/melanoma), CN10 (M1-like-macrophages/M2-like-macrophages/melanoma) and CN12 (Cytotoxic-T-cells/Helper-T-cells/melanoma) was associated with longer overall survival after diagnosis with MBM (p < 0.01). Conclusions: Proportion and proximity of anti-tumoral monocyte and T-cell populations may play a key role in modulating tumor response and overall survival for patients with MBM, including for patients with LD or for patients treated with ICIs.

Biomechanical and metabolic factors increase the risk for osteoarthritis (OA) by causing supraphysiological stresses on joint tissues. Chronic exposure to these stresses contributes to failure of the joint organ system, resulting in pain and loss of function for patients with OA. The synovium is vital for joint organ health but during OA, synovial inflammation and damage are associated with worse outcomes including pain. Unfortunately, the separate and combined effects of metabolic and biomechanical stresses on synovial tissues are not well understood. In this study, metabolic syndrome (MetS) was associated with worse knee pain in patients with early-stage knee OA, suggesting that metabolic stress may act on synovial tissues during early-stage OA, exacerbating outcomes. In a rat model of experimental knee OA, the combined effects of biomechanical and metabolic stresses induced worse knee pain, cartilage damage, and synovial inflammation than biomechanical stress alone. Further, single-cell RNA sequencing of synovial macrophages and fibroblasts identified earlier metabolic (glycolytic and respiratory) shifts, neurogenesis, dysregulated communication, and cell activation when metabolic and biomechanical stresses were combined. Lastly, using a direct contact co-culture system, we showed that metabolic stress alters macrophage-fibroblast communication leading to increased expression of Htra1, a pathogenic protease in OA. This study identifies novel mechanisms that may represent amenable therapeutic targets for patients experiencing MetS and OA. ### Competing Interest Statement CTA is a consultant for Abbvie, Amgen, Bristol Myers Squibb, Celgene, Fresenius Kabi, Gilead, Janssen, Merck, Novartis, Pfizer, Hoffmaan LaRoche, Sandoz, Sanofi-Genzyme, and UCB.

Somatic copy number alterations (SCNAs) are prevalent in cancer and play a significant role in both tumorigenesis and therapeutic resistance. While focal SCNAs have been extensively studied, the impact of larger arm-level SCNAs remains poorly understood. Here, we investigated the association between arm-level SCNAs and overall survival in triple-negative breast cancer (TNBC), an aggressive subtype of breast cancer lacking targeted therapies. We identified frequent arm-level SCNAs, including 21q gain and 7p gain, which correlated with poor overall survival in TNBC patients. Further, we identified the expression of specific genes within these SCNAs associated with survival. Notably, we found that the expression of RIPK4, a gene located on 21q, exhibited a strong correlation with poor overall survival. In functional assays, we demonstrated that targeting Ripk4 in a murine lung metastatic TNBC model significantly reduced tumor burden, improved survival, and increased CD4+ and CD8+ T cell infiltration. RIPK4 enhanced the survival of triple-negative breast cancer cells at secondary sites, thereby facilitating the formation of metastatic lesions. Our findings highlight the significance of arm-level SCNAs in breast cancer progression and identify RIPK4 as a putative driver of TNBC metastasis and immunosuppression.

Importance To date, no meta-analyses have comprehensively assessed the association of neoadjuvant chemoimmunotherapy with clinical outcomes in non–small cell lung cancer (NSCLC) in randomized and nonrandomized settings. In addition, there exists controversy concerning the efficacy of neoadjuvant chemoimmunotherapy for patients with NSCLC with programmed cell death 1 ligand 1 (PD-L1) levels less than 1%. Objective To compare neoadjuvant chemoimmunotherapy with chemotherapy by adverse events and surgical, pathological, and efficacy outcomes using recently published randomized clinical trials and nonrandomized trials. Data Sources MEDLINE and Embase were systematically searched from January 1, 2013, to October 25, 2023, for all clinical trials of neoadjuvant chemoimmunotherapy and chemotherapy that included at least 10 patients. Study Selection Observational studies and trials reporting the use of neoadjuvant radiotherapy, including chemoradiotherapy, molecular targeted therapy, or immunotherapy monotherapy, were excluded. Main Outcomes and Measures Surgical, pathological, and efficacy end points and adverse events were pooled using a random-effects meta-analysis. Results Among 43 eligible trials comprising 5431 patients (4020 males [74.0%]; median age range, 55-70 years), there were 8 randomized clinical trials with 3387 patients. For randomized clinical trials, pooled overall survival (hazard ratio, 0.65; 95% CI, 0.54-0.79; I 2 = 0%), event-free survival (hazard ratio, 0.59; 95% CI, 0.52-0.67; I 2 = 14.9%), major pathological response (risk ratio, 3.42; 95% CI, 2.83-4.15; I 2 = 31.2%), and complete pathological response (risk ratio, 5.52; 95% CI, 4.25-7.15; I 2 = 27.4%) favored neoadjuvant chemoimmunotherapy over neoadjuvant chemotherapy. For patients with baseline tumor PD-L1 levels less than 1%, there was a significant benefit in event-free survival for neoadjuvant chemoimmunotherapy compared with chemotherapy (hazard ratio, 0.74; 95% CI, 0.62-0.89; I 2 = 0%). Conclusion and Relevance This study found that neoadjuvant chemoimmunotherapy was superior to neoadjuvant chemotherapy across surgical, pathological, and efficacy outcomes. These findings suggest that patients with resectable NSCLC with tumor PD-L1 levels less than 1% may have an event-free survival benefit with neoadjuvant chemoimmunotherapy.

AbstractCyclin-dependent kinase 4/6 (CDK4/6) inhibitors are approved for breast cancer treatment and show activity against other malignancies, including KRAS-mutant non–small cell lung cancer (NSCLC). However, the clinical efficacy of CDK4/6 inhibitors is limited due to frequent drug resistance and their largely cytostatic effects. Through a genome-wide cDNA screen, we identified that bromodomain-containing protein 4 (BRD4) overexpression conferred resistance to the CDK4/6 inhibitor palbociclib in KRAS-mutant NSCLC cells. Inhibition of BRD4, either by RNA interference or small-molecule inhibitors, synergized with palbociclib to induce senescence in NSCLC cells and tumors, and the combination prolonged survival in a KRAS-mutant NSCLC mouse model. Mechanistically, BRD4-inhibition enhanced cell-cycle arrest and reactive oxygen species (ROS) accumulation, both of which are necessary for senescence induction; this in turn elevated GPX4, a peroxidase that suppresses ROS-triggered ferroptosis. Consequently, GPX4 inhibitor treatment selectively induced ferroptotic cell death in the senescent cancer cells, resulting in tumor regression. Cotargeting CDK4/6 and BRD4 also promoted senescence and ferroptosis vulnerability in pancreatic and breast cancer cells. Together, these findings reveal therapeutic vulnerabilities and effective combinations to enhance the clinical utility of CDK4/6 inhibitors.Significance:The combination of cytostatic CDK4/6 and BRD4 inhibitors induces senescent cancer cells that are primed for activation of ferroptotic cell death by targeting GPX4, providing an effective strategy for treating cancer.

Glioblastoma is the most common and deadliest brain tumour in adults, with a median survival of 15 months under the current standard of care. Immunotherapies like immune checkpoint inhibitors and oncolytic viruses have been extensively studied to improve this endpoint. However, most thus far have failed. To improve the efficacy of immunotherapies to treat glioblastoma, new single-cell imaging modalities like imaging mass cytometry can be leveraged and integrated with computational models. This enables a better understanding of the tumour microenvironment and its role in treatment success or failure in this hard-to-treat tumour. Here, we implemented an agent-based model that allows for spatial predictions of combination chemotherapy, oncolytic virus, and immune checkpoint inhibitors against glioblastoma. We initialised our model with patient imaging mass cytometry data to predict patient-specific responses and found that oncolytic viruses drive combination treatment responses determined by intratumoral cell density. We found that tumours with higher tumour cell density responded better to treatment. When fixing the number of cancer cells, treatment efficacy was shown to be a function of CD4 + T cell and, to a lesser extent, of macrophage counts. Critically, our simulations show that care must be put into the integration of spatial data and agent-based models to effectively capture intratumoral dynamics. Together, this study emphasizes the use of predictive spatial modelling to better understand cancer immunotherapy treatment dynamics, while highlighting key factors to consider during model design and implementation.