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Background The Wnt receptors ROR1 and ROR2 are generating increased interest as cancer therapeutic targets but remain understudied in pancreatic ductal adenocarcinoma (PDAC). Compared to canonical Wnt/ β-catenin signalling, the role of noncanonical Wnt signalling in PDAC remains largely unknown. Only one study has investigated the prognostic significance of the noncanonical Wnt signalling receptor, ROR2 in PDAC. No studies have investigated the prognostic role of ROR1 in PDAC. Methods Here, we performed analysis of ROR1 and ROR2 mRNA expression in three publicly available datasets ICGC-PACA-AU (n = 81), TCGA-PAAD (n = 150) and CPTAC-PDAC (n = 137). ROR1 and ROR2 protein expression from the CPTAC-PDAC discovery cohort were also analysed. Immunohistochemistry (IHC) using the validated anti ROR1 monoclonal antibody (4A5) was performed on the Australian Pancreatic Cancer Genome Initiative (APGI) cohort of PDAC samples (n = 152). Association between ROR1 cytoplasmic staining intensity and clinicopathological parameters including stage, grade and overall survival (OS) was investigated. Results High ROR1 mRNA expression levels correlated with a favourable OS outcome in all of the ICGC-PACA-AU, TCGA-PAAD and CPTAC-PDAC cohorts. ROR1 protein expression was not associated with stage, grade or OS in the APGI cohort. Conclusion ROR1 and ROR2 have potential as prognostic markers when measured at the mRNA level in PDAC. Our IHC cohort did not support ROR1 protein expression in predicting OS, and highlighted the discrepancy of prognostic biomarkers when measured by MS, IHC and RNAseq.

Simple Summary Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid malignancies, with a five-year survival rate of only ~10%. Pancreatic tissue becomes increasingly fibrotic (known as desmoplasia) during cancer development and progression. This extensive, heterogeneous reaction is largely mediated through the actions of stromal cells such as cancer-associated fibroblasts (CAFs). In this review, we will discuss how heterotypical reciprocal tumor-stromal and tumor-immune cell interactions in the pancreatic tumor microenvironment (TME) can both promote and restrain PDAC development and progression, with particular focus on the role of extracellular matrix (ECM) in potentiating tumor cell proliferation, survival, metastasis, and treatment resistance. We also give a snapshot of the current and emerging stromal co-therapies used in combination with chemotherapy or immunotherapy to treat this highly deadly disease. Abstract Many cancer studies now recognize that disease initiation, progression, and response to treatment are strongly influenced by the microenvironmental niche. Widespread desmoplasia, or fibrosis, is fundamental to pancreatic cancer development, growth, metastasis, and treatment resistance. This fibrotic landscape is largely regulated by cancer-associated fibroblasts (CAFs), which deposit and remodel extracellular matrix (ECM) in the tumor microenvironment (TME). This review will explore the prognostic and functional value of the stromal compartment in predicting outcomes and clinical prognosis in pancreatic ductal adenocarcinoma (PDAC). We will also discuss the major dynamic stromal alterations that occur in the pancreatic TME during tumor development and progression, and how the stromal ECM can influence cancer cell phenotype, metabolism, and immune response from a biochemical and biomechanical viewpoint. Lastly, we will provide an outlook on the latest clinical advances in the field of anti-fibrotic co-targeting in combination with chemotherapy or immunotherapy in PDAC, providing insight into the current challenges in treating this highly aggressive, fibrotic malignancy.

Assessing drug response within live native tissue provides increased fidelity with regards to optimizing efficacy while minimizing off-target effects. Here, using longitudinal intravital imaging of a Rac1-Forster resonance energy transfer (FRET) biosensor mouse coupled with in vivo photoswitching to track intratumoral movement, we help guide treatment scheduling in a live breast cancer setting to impair metastatic progression. We uncover altered Rac1 activity at the center versus invasive border of tumors and demonstrate enhanced Rac1 activity of cells in close proximity to live tumor vasculature using optical window imaging. We further reveal that Rac1 inhibition can enhance tumor cell vulnerability to fluid-flow-induced shear stress and therefore improves overall anti-metastatic response to therapy during transit to secondary sites such as the lung. Collectively, this study demonstrates the utility of single-cell intravital imaging in vivo to demonstrate that Rac1 inhibition can reduce tumor progression and metastases in an autochthonous setting to improve overall survival.

The concept that extracellular vesicles (EVs) from the diet can be absorbed by the intestinal tract of the consuming organism, be bioavailable in various organs, and in-turn exert phenotypic changes is highly debatable. Here, we isolate EVs from both raw and commercial bovine milk and characterize them by electron microscopy, nanoparticle tracking analysis, western blotting, quantitative proteomics and small RNA sequencing analysis. Orally administered bovine milk-derived EVs survive the harsh degrading conditions of the gut, in mice, and is subsequently detected in multiple organs. Milk-derived EVs orally administered to mice implanted with colorectal and breast cancer cells reduce the primary tumor burden. Intriguingly, despite the reduction in primary tumor growth, milk-derived EVs accelerate metastasis in breast and pancreatic cancer mouse models. Proteomic and biochemical analysis reveal the induction of senescence and epithelial-to-mesenchymal transition in cancer cells upon treatment with milk-derived EVs. Timing of EV administration is critical as oral administration after resection of the primary tumor reverses the pro-metastatic effects of milk-derived EVs in breast cancer models. Taken together, our study provides context-based and opposing roles of milk-derived EVs as metastasis inducers and suppressors., Dietary extracellular vesicles (EVs) could potentially be absorbed by the intestinal tract of the host and exert multiple phenotypic changes. Here, the authors isolate and characterize EVs from raw and commercial bovine milk and show orally administered EVs to have a context specific role in promoting or suppressing primary tumor growth and metastasis in multiple mouse tumor models.

Description, Intravital imaging guides a personalized medicine approach to target mechanoreciprocity in pancreatic cancer., Pancreatic ductal adenocarcinoma (PDAC) is a highly metastatic, chemoresistant malignancy and is characterized by a dense, desmoplastic stroma that modulates PDAC progression. Here, we visualized transient manipulation of focal adhesion kinase (FAK), which integrates bidirectional cell-environment signaling, using intravital fluorescence lifetime imaging microscopy of the FAK-based Förster resonance energy transfer biosensor in mouse and patient-derived PDAC models. Parallel real-time quantification of the FUCCI cell cycle reporter guided us to improve PDAC response to standard-of-care chemotherapy at primary and secondary sites. Critically, micropatterned pillar plates and stiffness-tunable matrices were used to pinpoint the contribution of environmental cues to chemosensitization, while fluid flow–induced shear stress assessment, patient-derived matrices, and personalized in vivo models allowed us to deconstruct how FAK inhibition can reduce PDAC spread. Last, stratification of PDAC patient samples via Merlin status revealed a patient subset with poor prognosis that are likely to respond to FAK priming before chemotherapy.

Today, there are 310 million surgical procedures performed worldwide every year, and an additional 143 million procedures are required to fill the current need. Complications from surgical procedures and subsequent deaths are highly dependent on the location and experience of the surgeon. Digital surgery aims to bring a new level of scientific rigor and transparency to the field of surgery by providing tools that augment the surgeon and staff with better perception and judgment, so as to improve the efficiency and outcomes for patients. By delivering care more efficiently, digital surgery will make surgical care accessible to a larger number of patients worldwide. By harnessing data, optimizing best practices, and mentoring surgeons on how to deliver quality care consistently, it will reduce the variability of outcomes and identify the key factors to improve them.

Most facial bones, including frontal bones, are derived from neural crest cells through intramembranous ossification. Fibroblast growth factor receptor 1 (Fgfr1) plays a pivotal role in craniofacial bone development, and loss of Fgfr1 leads to cleft palate and facial cleft defects in newborn mice. However, the potential role of the Fgfr1 gene in neural crest cell-mediated craniofacial development remains unclear. To investigate the role of Fgfr1 in neural crest cells, we analyzed Wnt1-Cre;Fgfr1flox/flox mice. Our results show that specific knockout of Fgfr1 in neural crest cells induced heterotopic chondrogenesis and osteogenesis at the interface of the anterior portions of frontal bones. We observed that heterotopic bone formation continued through postnatal day 28, whereas heterotopic chondrogenesis lasted only through the embryonic period. In summary, our results indicate that loss of Fgfr1 in neural crest cells leads to heterotopic chondrogenesis and osteogenesis.

Whereas genomic aberrations in the SLIT-ROBO pathway are frequent in pancreatic ductal adenocarcinoma (PDAC), their function in the pancreas is unclear. Here we report that in pancreatitis and PDAC mouse models, epithelial Robo2 expression is lost while Robo1 expression becomes most prominent in the stroma. Cell cultures of mice with loss of epithelial Robo2 (Pdx1Cre;Robo2F/F) show increased activation of Robo1+ myofibroblasts and induction of TGF-β and Wnt pathways. During pancreatitis, Pdx1Cre;Robo2F/F mice present enhanced myofibroblast activation, collagen crosslinking, T-cell infiltration and tumorigenic immune markers. The TGF-β inhibitor galunisertib suppresses these effects. In PDAC patients, ROBO2 expression is overall low while ROBO1 is variably expressed in epithelium and high in stroma. ROBO2low;ROBO1high patients present the poorest survival. In conclusion, Robo2 acts non-autonomously as a stroma suppressor gene by restraining myofibroblast activation and T-cell infiltration. ROBO1/2 expression in PDAC patients may guide therapy with TGF-β inhibitors or other stroma /immune modulating agents., SLIT-ROBO alterations arise in pancreatic ductal adenocarcinoma (PDAC), but their role in the pancreas is unclear. Here, the authors use mouse models to show that loss of epithelial Robo2 activates the neighbouring stroma via TGF-β signalling; findings are relevant to PDAC patients, where ROBO expression correlates with survival outcomes.

Summary Application of advanced intravital imaging facilitates dynamic monitoring of pathway activity upon therapeutic inhibition. Here, we assess resistance to therapeutic inhibition of the PI3K pathway within the hypoxic microenvironment of pancreatic ductal adenocarcinoma (PDAC) and identify a phenomenon whereby pronounced hypoxia-induced resistance is observed for three clinically relevant inhibitors. To address this clinical problem, we have mapped tumor hypoxia by both immunofluorescence and phosphorescence lifetime imaging of oxygen-sensitive nanoparticles and demonstrate that these hypoxic regions move transiently around the tumor. To overlay this microenvironmental information with drug response, we applied a FRET biosensor for Akt activity, which is a key effector of the PI3K pathway. Performing dual intravital imaging of drug response in different tumor compartments, we demonstrate an improved drug response to a combination therapy using the dual mTORC1/2 inhibitor AZD2014 with the hypoxia-activated pro-drug TH-302., Graphical Abstract, Highlights • Hypoxia presents a moving pocket of resistance in pancreatic ductal adenocarcinoma. • Dual intravital imaging allows live tracking of drug response in hypoxic regions. • Combination with a hypoxia-activated pro-drug alleviates resistance. • This has implications for combatting resistance in a broad range of therapies., Intravital imaging facilitates the real-time tracking and targeting of moving hypoxic regions within pancreatic ductal adenocarcinoma. Using this approach, Conway et al. alleviate hypoxia-induced resistance to a dual mTORC1/2 inhibitor AZD2014, improving PI3K pathway inhibition and demonstrating a powerful dual imaging modality applicable to targeting other pathways and cancers.

The small GTPase RhoA is a master regulator of signalling in cell-extracellular matrix interactions. RhoA signalling is critical to many cellular processes including migration, mechanotransduction, and is often disrupted in carcinogenesis. Investigating RhoA activity in a native tissue environment is challenging using conventional biochemical methods; we therefore developed a RhoA-FRET biosensor mouse, employing the adaptable nature of intravital imaging to a variety of settings. Mechanotransduction was explored in the context of osteocyte processes embedded in the calvaria responding in a directional manner to compression stress. Further, the migration of neutrophils was examined during in vivo “chemotaxis” in wound response. RhoA activity was tightly regulated during tissue remodelling in mammary gestation, as well as during mammary and pancreatic carcinogenesis. Finally, pharmacological inhibition of RhoA was temporally resolved by the use of optical imaging windows in fully developed pancreatic and mammary tumours in vivo. The RhoA-FRET mouse therefore constitutes a powerful tool to facilitate development of new inhibitors targeting the RhoA signalling axis.

Immunotherapies have not yielded significant clinical benefits for pancreatic ductal adenocarcinoma (PDA) because of the existence of an immunosuppressive tumour microenvironment (TME) characterized by a desmoplastic stroma containing infiltrated immune cells and activated pancreatic stellate cells (PSCs). This study aims to investigate the involvement of PAK1 in anti-tumour immunity. In PDA patients, low PAK1 expression, low activation of PSC and high CD8+ T cell/PAK1 ratios correlated with longer overall survival. In a murine PDA model, PAK1 knockout increased intra-tumoral CD4+ and CD8+ T cells, inhibited PSCs activation and extended survival. Inhibition of PAK1 reduced PSC-stimulated PDA cell proliferation and migration, blocked PSC-mediated protection of PDA cells from killing by cytotoxic lymphocytes and decreased intrinsic and PSC-stimulated PD-L1 expression in PDA cells, which further sensitized PDA cells to cytotoxic lymphocytes. Inhibition of PAK1 stimulates anti-tumour immunity by increasing intra-tumoral CD4+ and CD8+ T cells, and by sensitizing PDA cells to killing by cytotoxic lymphocytes via down-regulation of intrinsic and PSC-stimulated PD-L1 expression. PAK1 inhibitors, especially in combination with immune checkpoint inhibitors may result in improved efficacy of immunotherapy of PDA.

Intravital microscopy can provide unique insights into the function of biological processes in a native context. However, physiological motion caused by peristalsis, respiration and the heartbeat can present a significant challenge, particularly for functional readouts such as fluorescence lifetime imaging (FLIM), which require longer acquisition times to obtain a quantitative readout. Here, we present and benchmark Galene, a versatile multi-platform software tool for image-based correction of sample motion blurring in both time resolved and conventional laser scanning fluorescence microscopy data in two and three dimensions. We show that Galene is able to resolve intravital FLIM-FRET images of intra-abdominal organs in murine models and NADH autofluorescence of human dermal tissue imaging subject to a wide range of physiological motions. Thus, Galene can enable FLIM imaging in situations where a stable imaging platform is not always possible and rescue previously discarded quantitative imaging data., eLife digest Understanding how molecules and cells behave in living animals can give researchers key insights into what goes wrong in diseases such as cancer, and how well potential treatments for these diseases work. A number of tools help us to see these processes. For example, fluorescent ‘biosensors’ change colour to tell us how active a particular protein is. This can indicate how well a drug works in different parts of a tumour. High resolution microscopy makes it possible to image events happening in single cells, or even specific parts of a cell. However, small movements like those due to the heartbeat or breathing can blur the images, making it difficult to study living animals. This is particularly problematic for images that take several minutes to capture. Warren et al. have now developed a new open source software tool called Galene. The tool can correct for small movements in images collected by a technique called fluorescence lifetime imaging microscopy (FLIM). As a result, clear images can be captured in situations that were not previously possible. For example, Warren et al. watched cancer cells migrating to the liver of a mouse from the spleen over 24 hours, and, using a fluorescent biosensor, showed that a repurposed drug interferes with how well the cells can attach to the liver. In addition, Warren et al. used the software to take steady 3D images of human skin in a volunteer’s arm, which could be used to study drug penetration. Galene could help researchers to study a wide range of biological processes in living animals. The software can also be applied to existing data to clean up blurred images. In the future Galene could be further developed to work with the imaging techniques used during surgery. For example, surgeons could use it to help them find the edges of tumours.

Cancer-associated fibroblasts (CAFs) are one of the most significant components in the tumour microenvironment (TME), where they can perform several protumourigenic functions. Several studies have recently reported that CAFs are more heterogenous and plastic than was previously thought. As such, there has been a shift in the field to study CAF subpopulations and the emergent functions of these subsets in tumourigenesis. In this review, we explore how different aspects of CAF heterogeneity are defined and how these manifest in multiple cancers, with a focus on pancreatic ductal adenocarcinoma (PDAC). We also discuss therapeutic approaches to selectively target protumourigenic CAF functions, while avoiding normal fibroblasts, providing insight into the future of stromal targeting for the treatment of PDAC and other solid tumours.

Pancreatic ductal adenocarcinoma (PDAC) is among the most deadly solid tumours. This is due to a generally late-stage diagnosis of a primarily treatment-refractory disease. Several large-scale sequencing and mass spectrometry approaches have identified key drivers of this disease and in doing so highlighted the vast heterogeneity of lower frequency mutations that make clinical trials of targeted agents in unselected patients increasingly futile. There is a clear need for improved biomarkers to guide effective targeted therapies, with biomarker-driven clinical trials for personalised medicine becoming increasingly common in several cancers. Interestingly, many of the aberrant signalling pathways in PDAC rely on downstream signal transduction through the mitogen-activated protein kinase and phosphoinositide 3-kinase (PI3K) pathways, which has led to the development of several approaches to target these key regulators, primarily as combination therapies. The following review discusses the trend of PDAC therapy towards molecular subtyping for biomarker-driven personalised therapies, highlighting the key pathways under investigation and their relationship to the PI3K pathway.

Purpose The purpose of this study was to evaluate the quality of reporting in the abstracts of oncology systematic reviews using PRISMA guidelines for abstract writing. Methods Oncology systematic reviews and meta-analyses from four journals - The Lancet Oncology , Clinical Cancer Research , Cancer Research , and the Journal of Clinical Oncology - were selected using a PubMed search. The resulting 337 abstracts were sorted for eligibility and 182 were coded based on a standardized abstraction manual constructed from the PRISMA criteria. Eligible systematic reviews were coded independently and later verified by a second coder, with disagreements handled by consensus. One hundred eighty-two abstracts comprised the final sample. Results The number of included studies, information regarding main outcomes, and general interpretation of results were described in the majority of abstracts. In contrast, risk of bias or methodological quality appraisals, the strengths and limitations of evidence, funding sources, and registration information were rarely reported. By journal, the most notable difference was a higher percentage of funding sources reported in Lancet Oncology . No detectable upward trend was observed on mean abstract scores after publication of the PRISMA extension for abstracts. Conclusion Overall, the reporting of essential information in oncology systematic review and meta-analysis abstracts is suboptimal and could be greatly improved.

Tumour metastasis is a dynamic and systemic process. It is no longer seen as a tumour cell-autonomous program but as a multifaceted and complex series of events, which is influenced by the intrinsic cellular mutational burden of cancer cells and the numerous bidirectional interactions between malignant and non-malignant cells and fine-tuned by the various extrinsic cues of the extracellular matrix. In cancer biology, metastasis as a process is one of the most technically challenging aspects of cancer biology to study. As a result, new platforms and technologies are continually being developed to better understand this process. In this review, we discuss some of the recent advances in metastasis and how the information gleaned is re-shaping our understanding of metastatic dissemination.

The cellular and molecular basis of stromal cell recruitment, activation and crosstalk in carcinomas is poorly understood, limiting the development of targeted anti-stromal therapies. In mouse models of triple negative breast cancer (TNBC), Hedgehog ligand produced by neoplastic cells reprograms cancer-associated fibroblasts (CAFs) to provide a supportive niche for the acquisition of a chemo-resistant, cancer stem cell (CSC) phenotype via FGF5 expression and production of fibrillar collagen. Stromal treatment of patient-derived xenografts with smoothened inhibitors (SMOi) downregulates CSC markers expression and sensitizes tumors to docetaxel, leading to markedly improved survival and reduced metastatic burden. In the phase I clinical trial EDALINE, 3 of 12 patients with metastatic TNBC derived clinical benefit from combination therapy with the SMOi Sonidegib and docetaxel chemotherapy, with one patient experiencing a complete response. These studies identify Hedgehog signaling to CAFs as a novel mediator of CSC plasticity and an exciting new therapeutic target in TNBC., Stromal cell recruitment, activation and crosstalk with cancer cells is poorly understood. Here, the authors demonstrate that cancer cell-derived Hedgehog ligand triggers stromal remodeling that in turn induces a cancer-stem-cell like, drug-resistant phenotype of nearby cancer cells while treatment with smoothened inhibitors reverses these phenotypes.

Organotypic co-cultures bridge the gap between standard two-dimensional culture and mouse models. Such assays increase the fidelity of pre-clinical studies, to better inform lead compound development and address the increasing attrition rates of lead compounds within the pharmaceutical industry, which are often a result of screening in less faithful two-dimensional models. Using large-scale acid-extraction techniques, we demonstrate a step-by-step process to isolate collagen I from commercially available animal byproducts. Using the well-established rat tail tendon collagen as a benchmark, we apply our novel kangaroo tail tendon collagen as an alternative collagen source for our screening-ready three-dimensional organotypic co-culture platform. Both collagen sources showed equal applicability for invasive, proliferative or survival assessment of well-established cancer models and clinically relevant patient-derived cancer cell lines. Additional readouts were also demonstrated when comparing these alternative collagen sources for stromal contributions to stiffness, organization and ultrastructure via atomic force microscopy, second harmonic generation imaging and scanning electron microscopy, among other vital biological readouts, where only minor differences were found between the preparations. Organotypic co-cultures represent an easy, affordable and scalable model to investigate drug responses within a physiologically relevant 3D platform.

The cellular and molecular basis of stromal cell recruitment, activation and crosstalk in carcinomas is poorly understood, limiting the development of targeted anti-stromal therapies. In mouse models of triple negative breast cancer (TNBC), Hh ligand produced by neoplastic cells reprogrammed cancer-associated fibroblast (CAF) gene expression, driving tumor growth and metastasis. Hh-activated CAFs upregulated expression of FGF5 and production of fibrillar collagen, leading to FGFR and FAK activation in adjacent neoplastic cells, which then acquired a stem-like, drug-resistant phenotype. Treatment with smoothened inhibitors (SMOi) reversed these phenotypes. Stromal treatment of TNBC patient-derived xenograft (PDX) models with SMOi downregulated the expression of cancer stem cell markers and sensitized tumors to docetaxel, leading to markedly improved survival and reduced metastatic burden. In the phase I clinical trial EDALINE, 3 of 12 patients with metastatic TNBC derived clinical benefit from combination therapy with the SMOi Sonidegib and docetaxel chemotherapy, with one patient experiencing a complete response. Markers of pathway activity correlated with response. These studies identify Hh signaling to CAFs as a novel mediator of cancer stem cell plasticity and an exciting new therapeutic target in TNBC.SIGNIFICANCECompared to other breast cancer subtypes, TNBCs are associated with significantly worse patient outcomes. Standard of care systemic treatment for patients with non-BRCA1/2 positive TNBC is cytotoxic chemotherapy. However, the failure of 70% of treated TNBCs to attain complete pathological response reflects the relative chemoresistance of these tumors. New therapeutic strategies are needed to improve patient survival and quality of life. Here, we provide new insights into the dynamic interactions between heterotypic cells within a tumor. Specifically, we establish the mechanisms by which CAFs define cancer cell phenotype and demonstrate that the bidirectional CAF-cancer cell crosstalk can be successfully targeted in mice and humans using anti-stromal therapy.

Systematic reviews synthesize data across multiple studies to answer a research question, and an important component of the review process is to evaluate the heterogeneity of primary studies considered for inclusion. Little is known, however, about the ways that systematic reviewers evaluate heterogeneity, especially in clinical specialties like oncology. We examined a sample of systematic reviews from this body of literature to determine how meta-analysts assessed and reported heterogeneity. A PubMed search of 6 oncology journals was conducted to locate systematic reviews and meta-analyses. Two coders then independently evaluated the manuscripts for 10 different elements based on an abstraction manual. The initial PubMed search yielded 337 systematic reviews from 6 journals. Screening for exclusion criteria (nonsystematic reviews, genetic studies, individual patient data, etc.) found 155 articles that did not meet the definition of a systematic review. This left a final sample of 182 systematic reviews across 4 journals. Of these reviews, 50% (91/182) used varying combinations of heterogeneity tests, and of those, 16% (15/91) of review authors noted excessive heterogeneity and opted to not perform a meta-analysis. Of the studies that measured heterogeneity, 51% (46/91) used a random-effects model, 7% (8/91) used a fixed-effects model, and 43% (39/91) used both. We conclude that use of quantitative and qualitative heterogeneity measurement tools are underused in the 4 oncology journals evaluated. Such assessments should be routinely applied in meta-analyses.

Background Publication bias is an over-representation of statistically significant results in the published literature and may exaggerate summary effect estimates in oncology systematic reviews. Omitting non-significant results in systematic reviews may therefore affect clinical decision-making. We investigate ways that systematic reviewers attempted to limit publication bias during the search process as well as the statistical methods used to evaluate it. For a subset of reviews not reporting publication bias evaluations, we carried out our own assessments for publication bias to determine its likelihood among these reviews. Design We examined systematic reviews from the top five highest impact factor oncology journals published between 2007 and 2015. Systematic reviews were screened for eligibility and qualifying reviews (n = 182) were coded for relevant publication bias study characteristics by two authors. A re-analysis of reviews not initially evaluating for publication bias was carried out using Egger's regression, trim-and-fill, and selection models. Results Of the 182 systematic reviews, roughly half carried out a hand search to locate additional studies. Conference abstracts were the most commonly reported form of gray literature, followed by clinical trials registries. Fifty-one reviews reported publication bias evaluations. The most common method was the funnel plot (80%, 41/51) followed by Egger's regression (59%, 30/51) and Begg's test (43%, 22/51). Our publication bias evaluations on non-reporting reviews suggest that the degree of publication bias depends on the method employed. Conclusion Our study shows publication bias assessments are not frequently used in oncology systematic reviews. Furthermore, evidence of publication bias was found in a subset of non-reporting reviews. Systematic reviewers in oncology are encouraged to conduct such analyses when appropriate and to employ more robust methods for both mitigating and evaluating publication bias.

Basic in vitro systems can be used to model and assess complex diseases, such as cancer. Recent advances in this field include the incorporation of multiple cell types and extracellular matrix proteins into three-dimensional (3D) models to recapitulate the structure, organization and functionality of live tissue in situ. Cells within such a 3D environment behave very differently from cells on two-dimensional (2D) substrates, as cell-matrix interactions trigger signalling pathways and cellular responses in 3D, which may not be observed in 2D. Thus, the use of 3D systems can be advantageous for the assessment of disease progression over 2D set-ups alone. Here, we highlight the current advantages and challenges of employing 3D systems in the study of cancer and provide an overview to guide the appropriate use of distinct models in cancer research.

Introduction The extensive stromal deposition and remodelling of pancreatic ductal adenocarcinoma (PDAC) alters mechanical tumour-stroma integrations, promoting tumour development and metastatic spread. Few effective therapies mean that PDAC is predicted to be the second leading cause of cancer mortality by 2030. In highly metastatic mouse models of PDAC, we observed enhanced extracellular matrix (ECM) deposition and remodelling throughout disease progression. This was paralleled by an increased focal adhesion kinase (FAK) expression and activity, suggesting a role for FAK in the increased desmoplastic reaction that is typical of PDAC. Consequently, fine tuned manipulation of the dense stroma by streamlined FAK inhibition (FAKi) presents a novel opportunity for PDAC management and improved response to chemotherapy. Material and methods Intravital imaging of the FUCCI cell cycle reporter was used to dynamically monitor tumour cell response to combined FAKi and standard-of-care therapy with gemcitabine/Abraxane. This was overlaid with second harmonic generation (SHG) imaging of collagen fibres, to assess the efficacy of FAKi to disrupt the dense PDAC ECM. To complement our in vivo metastatic studies, we used sophisticated 3D in vitro models of invasion, anchorage-independent growth and shear-stress, in both primary and patient-derived PDAC cell lines. Results and discussions We systematically demonstrated that using FAKi to modulate ECM prior to standard-of-care therapy enhanced treatment efficacy whilst also reducing metastatic spread in vivo . Further analysis revealed that FAKi sensitised cells to shear stress, impairing metastatic colonisation and the establishment of fibrotic niches in the liver. Stratified patient samples revealed a subset of patients likely to respond to FAK priming regimes, where fine-tuned ECM manipulation prior to chemotherapy may offer a novel opportunity in metastatic PDAC. Conclusion This subtype-specific fine-tuned stromal manipulation may allow us to maximise gemcitabine/Abraxane therapy whilst reducing drug toxicity and potentially reducing metastatic spread in a preclinical setting.

Introduction The ‘Mutated in colorectal cancer’ (MCC) gene was originally discovered due to its linkage with the APC gene. MCC is silenced through gene promoter methylation in colorectal cancer (CRC) but its significance has been poorly understood. MCC promoter methylation occurs early in premalignant tumours and is associated with increased lymph node metastasis in advanced CRC. Here we determined the consequences of MCC knockdown on cell-cell adhesion and invasiveness of colon cancer cells and further characterised the gene methylation in patient tumours. Material and methods MCC promoter methylation was determined in a cohort of 365 CRC and compared with clinicopathological features, with research ethics approval by the Sydney Local Health District. MCC expression was stably knocked down in HCT116 colon cancer cells or induced in HCT15 cells using lentiviral vectors. The impact of MCC knockdown on invasiveness was determined using an organotypic assay and on cell-cell adhesion with dispase and transepithelial electrical resistance (TEER) assays. Protein complexes were characterised using Blue-Native PAGE, co-immunoprecipitation, immunofluorescence and Proximity Ligation Assay (PLA). Results and discussions MCC promoter methylation was found in 58% of cancers in the right colon, 28% in the left colon and 24% in the rectum. Methylation was associated with larger, poorly differentiated, circumferential or mucinous tumours, and higher T stage that indicates increased invasiveness. We established that the MCC protein interacts with the E-cadherin/beta-catenin complex in HCT116 and HCT15 cells. MCC knockdown in HCT116 cells caused a reduction in E-cadherin protein level, disrupted cell-cell adhesive strength and integrity, increased cell invasiveness and hepatocyte growth factor-induced cell scatter. MCC expression in HCT15 cells had the opposite effect in dispase, TEER and PLA assays. The invasive properties induced by MCC knockdown were abrogated by dasatinib, a candidate anti-invasive drug. Thus we have described a novel function of MCC in the regulation of E-cadherin mediated functions. Conclusion Our study advances current understanding of the protein-protein interactions that control cell-cell adhesion and suppress epithelial-mesenchymal-transition. Potential therapies exploiting our findings may include strengthening cellular junctions with dasatinib or other anti-invasive combination therapies.

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis, being predicted to become the second leading cause of cancer-related death by 2030. Chronic pancreatitis is a risk factor for PDAC and both diseases are characterized by a strong desmoplastic response, comprised of activated myofibroblasts and immune cell infiltrates. Genomic aberrations in the SLIT-ROBO pathway are frequent in PDAC. Nevertheless, their role in the pancreas is unclear. We have used an integrative approach combining the study of murine models and PDAC patients with the objective of unraveling the function of the SLIT-ROBO signaling pathway in pancreatic disease. RNA expression of SLIT-ROBO genes was analyzed in murine normal pancreas, pancreatitis and PDAC. Primary cell cultures and experimental pancreatitis were studied using pancreas-specific Robo2 (Pdx1-Cre;Robo2F/F) and whole-body Slit1 (Slit1-/-) knockout mice. Gene and protein expression were assessed in a cohort of PDAC patients (n=109). In mouse pancreatitis and PDAC, epithelial Robo2 expression is lost while Robo1 expression becomes most prominent in the stroma. Pdx1Cre;Robo2F/F pancreatic cell cultures showed increased activation of Robo1-positive myofibroblasts and induction of TGF-β and Wnt pathways. Likewise, induction of pancreatitis in Pdx1Cre;Robo2F/F mice enhanced myofibroblast activation, collagen crosslinking, T-cell infiltration and tumorigenic immune markers. Similar results were obtained using Slit1-/- animals. Moreover, TGF-β inhibition using galunisertib treatment suppressed Robo2-mediated effects in the microenvironment. In patients, ROBO2 expression is overall low in PDAC, while ROBO1 is variably expressed in epithelium and high in the stroma. ROBO1 expression is correlated with markers of activated stroma, Wnt and TGF-β pathways. ROBO2low;ROBO1high subpopulation of patients present the poorest survival rates. In conclusion, Robo2 acts nonautonomously as a stroma suppressor gene by restraining myofibroblast activation and inflammation in the pancreatic microenvironment. ROBO1/2 expression is prognostic in PDAC patients and may guide therapy with TGF-β inhibitors or immunotherapies, currently being tested in clinical trials for advanced pancreatic cancer. Citation Format: Andreia V. Pinho, Mathias Van Bulck, Lorraine Chantrill, Mehreen Arshi, David Herrmann, Claire Vennin, APGI - Australian Pancreatic Cancer Genome Initiative, Anthony Gill, Paul Timpson, Andrew Biankin, Jianmin Wu, Ilse Rooman. ROBO2 is a stroma suppressor gene in the pancreas through regulation of TGF-β [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A100.

E-cadherin and β-catenin are key proteins that are essential in the formation of the epithelial cell layer in the colon but their regulatory pathways that are disrupted in cancer metastasis are not completely understood. Mutated in colorectal cancer (MCC) is a tumour suppressor gene that is silenced by promoter methylation in colorectal cancer and particularly in patients with increased lymph node metastasis. Here, we show that MCC methylation is found in 45% of colon and 24% of rectal cancers and is associated with proximal colon, poorly differentiated, circumferential and mucinous tumours as well as increasing T stage and larger tumour size. Knockdown of MCC in HCT116 colon cancer cells caused a reduction in E-cadherin protein level, which is a hallmark of epithelial-mesenchymal transition in cancer, and consequently diminished the E-cadherin/β-catenin complex. MCC knockdown disrupted cell-cell adhesive strength and integrity in the dispase and transepithelial electrical resistance assays, enhanced hepatocyte growth factor-induced cell scatter and increased tumour cell invasiveness in an organotypic assay. The Src/Abl inhibitor dasatinib, a candidate anti-invasive drug, abrogated the invasive properties induced by MCC deficiency. Mechanistically, we establish that MCC interacts with the E-cadherin/β-catenin complex. These data provide a significant advance in the current understanding of cell-cell adhesion in colon cancer cells.

The emerging standard of care for patients with inoperable pancreatic cancer is a combination of cytotoxic drugs gemcitabine and Abraxane, but patient response remains moderate. Pancreatic cancer development and metastasis occur in complex settings, with reciprocal feedback from microenvironmental cues influencing both disease progression and drug response. Little is known about how sequential dual targeting of tumor tissue tension and vasculature before chemotherapy can affect tumor response. We used intravital imaging to assess how transient manipulation of the tumor tissue, or "priming," using the pharmaceutical Rho kinase inhibitor Fasudil affects response to chemotherapy. Intravital Forster resonance energy transfer imaging of a cyclin-dependent kinase 1 biosensor to monitor the efficacy of cytotoxic drugs revealed that priming improves pancreatic cancer response to gemcitabine/Abraxane at both primary and secondary sites. Transient priming also sensitized cells to shear stress and impaired colonization efficiency and fibrotic niche remodeling within the liver, three important features of cancer spread. Last, we demonstrate a graded response to priming in stratified patient-derived tumors, indicating that fine-tuned tissue manipulation before chemotherapy may offer opportunities in both primary and metastatic targeting of pancreatic cancer. Refereed/Peer-reviewed

Background Metastatic disease is largely resistant to therapy and accounts for almost all cancer deaths. Myeloid cell leukemia-1 (MCL-1) is an important regulator of cell survival and chemo-resistance in a wide range of malignancies, and thus its inhibition may prove to be therapeutically useful. Methods To examine whether targeting MCL-1 may provide an effective treatment for breast cancer, we constructed inducible models of BIMs2A expression (a specific MCL-1 inhibitor) in MDA-MB-468 (MDA-MB-468-2A) and MDA-MB-231 (MDA-MB-231-2A) cells. Results MCL-1 inhibition caused apoptosis of basal-like MDA-MB-468-2A cells grown as monolayers, and sensitized them to the BCL-2/BCL-XL inhibitor ABT-263, demonstrating that MCL-1 regulated cell survival. In MDA-MB-231-2A cells, grown in an organotypic model, induction of BIMs2A produced an almost complete suppression of invasion. Apoptosis was induced in such a small proportion of these cells that it could not account for the large decrease in invasion, suggesting that MCL-1 was operating via a previously undetected mechanism. MCL-1 antagonism also suppressed local invasion and distant metastasis to the lung in mouse mammary intraductal xenografts. Kinomic profiling revealed that MCL-1 antagonism modulated Src family kinases and their targets, which suggested that MCL-1 might act as an upstream modulator of invasion via this pathway. Inhibition of MCL-1 in combination with dasatinib suppressed invasion in 3D models of invasion and inhibited the establishment of tumors in vivo. Conclusion These data provide the first evidence that MCL-1 drives breast cancer cell invasion and suggests that MCL-1 antagonists could be used alone or in combination with drugs targeting Src kinases such as dasatinib to suppress metastasis. Electronic supplementary material The online version of this article (doi:10.1186/s13058-016-0781-6) contains supplementary material, which is available to authorized users.

Background Patients with traumatic brain injury (TBI) are at high risk for venous thromboembolism (VTE), but physicians are cautious with chemical prophylaxis in these patients because of concern about exacerbating intracranial hemorrhage. We hypothesized that early use of chemical thromboprophylaxis would reduce VTE incidence without increasing intracranial hemorrhage. Study Design Records of all patients admitted with a TBI to a Level I trauma center from 2006 to 2008 were reviewed. TBI was defined as intracranial hemorrhage, hematoma, contusion, or diffuse axonal injury with a head Abbreviated Injury Scale score >2. Patients were excluded if they were discharged or died within 72 hours of admission. Chemical prophylaxis was defined as subcutaneous or intravenous unfractionated heparin or low molecular weight heparin before any VTE diagnosis. Progression of TBI was defined by worsening CT findings. VTE was defined as deep venous thrombosis or pulmonary embolus confirmed by radiology reports. Primary outcomes were progression of hemorrhage and VTE events. Results Eight hundred and twelve of the 1,258 patients admitted to the trauma center with a TBI met study criteria. Chemical thromboprophylaxis was given to 49.5% (n = 402). Mean head Abbreviated Injury Scale score was 3.4 in both groups. One hundred and sixty-nine patients started prophylaxis within 48 hours and 242 patients began within 72 hours. Patients receiving chemical prophylaxis had a lower incidence of VTE (1% versus 3%; p=0.019). Although not statistically significant, they also had a lower rate of injury progression, 3% versus 6% (p = 0.055). Conclusions Use of chemical thromboprophylaxis in TBI patients with a stable or improved head CT after 24 hours substantially reduces the incidence of VTE and does not increase the risk of progression of intracranial hemorrhage.

Summary E-cadherin-mediated cell-cell junctions play a prominent role in maintaining the epithelial architecture. The disruption or deregulation of these adhesions in cancer can lead to the collapse of tumor epithelia that precedes invasion and subsequent metastasis. Here we generated an E-cadherin-GFP mouse that enables intravital photobleaching and quantification of E-cadherin mobility in live tissue without affecting normal biology. We demonstrate the broad applications of this mouse by examining E-cadherin regulation in multiple tissues, including mammary, brain, liver, and kidney tissue, while specifically monitoring E-cadherin mobility during disease progression in the pancreas. We assess E-cadherin stability in native pancreatic tissue upon genetic manipulation involving Kras and p53 or in response to anti-invasive drug treatment and gain insights into the dynamic remodeling of E-cadherin during in situ cancer progression. FRAP in the E-cadherin-GFP mouse, therefore, promises to be a valuable tool to fundamentally expand our understanding of E-cadherin-mediated events in native microenvironments., Graphical Abstract, Highlights • The E-cadherin-GFP mouse allows in situ quantification of E-cadherin mobility • We monitored E-cadherin mobility during tissue homeostasis and disease development • Invasive pancreatic cancer driven by mutant Kras/p53 increases E-cadherin mobility • Dasatinib treatment reverts E-cadherin mobility and reinforces tumor cell junctions, Erami et al. generate an E-cadherin-GFP mouse to demonstrate real-time quantification of E-cadherin mobility using intravital photobleaching in a range of tissue types. They show that changes in E-cadherin mobility correlate with changes in cell junction integrity and invasiveness while demonstrating applications of the mouse for future drug discovery studies.

Factors secreted by tumor cells shape the local microenvironment to promote invasion and metastasis, as well as condition the premetastatic niche to enable secondary-site colonization and growth. In addition to this secretome, tumor cells have increased abundance of growth-promoting receptors at the cell surface. We found that the tyrosine phosphatase PTPN14 (also called Pez, which is mutated in various cancers) suppressed metastasis by reducing intracellular protein trafficking through the secretory pathway. Knocking down PTPN14 in tumor cells or injecting the peritoneum of mice with conditioned medium from PTPN14-deficient cell cultures promoted the growth and metastasis of breast cancer xenografts. Loss of catalytically functional PTPN14 increased the secretion of growth factors and cytokines, such as IL-8 (interleukin-8), and increased the abundance of EGFR (epidermal growth factor receptor) at the cell surface of breast cancer cells and of FLT4 (vascular endothelial growth factor receptor 3) at the cell surface of primary lymphatic endothelial cells. We identified RIN1 (Ras and Rab interactor 1) and PRKCD (protein kinase C-delta) as binding partners and substrates of PTPN14. Similar to cells overexpressing PTPN14, receptor trafficking to the cell surface was inhibited in cells that lacked PRKCD or RIN1 or expressed a nonphosphorylatable RIN1 mutant, and cytokine secretion was decreased in cells treated with PRKCD inhibitors. Invasive breast cancer tissue had decreased expression of PTPN14, and patient survival was worse when tumors had increased expression of the genes encoding RIN1 or PRKCD. Thus, PTPN14 prevents metastasis by restricting the trafficking of both soluble and membrane-bound proteins. Refereed/Peer-reviewed

E-cadherin-mediated cell-cell junctions play a physical role in maintaining normal epithelial architecture. The disruption or deregulation of these adhesions in cancer can lead to the collapse of tumor epithelia that precedes invasion and subsequent metastasis. Here, we have generated an E-cadherin-GFP(FRAP) biosensor mouse, which enables intravital photobleaching and quantification of E-cadherin mobility in live tissue, without affecting normal biology. We demonstrate using FRAP or FLIP, the broad applications of this mouse to examine E-cadherin regulation in multiple tissues including mammary, brain, liver and kidney, while specifically monitoring E-cadherin mobility during disease progression in the pancreas. We assess E-cadherin stability in native pancreatic tissue, upon genetic manipulation involving Kras and p53 or in response to anti-invasive drug treatment, and reveal new insights into the dynamic remodeling of E-cadherin during in situ cancer progression. Photobleaching in the E-cadherin-GFP(FRAP) mouse correlate directly with epithelial integrity and mechanical strength making the biosensor mouse a valuable tool to fundamentally expand our understanding of E-cadherin-mediated events in native micro-environments. This abstract is also being presented as Poster B23. Citation Format: David Herrmann, Zahra Erami, Sean Warren, Max Nobis, Astrid Magenau, Morghan Lucas, Claire Vennin, Ewan J. McGhee, Wilfred Leung, Nadine Reischmann, Agata Mrowinska, Juliane P. Schwarz, Shereen Kadir, Saadia A. Karim, Andrew D. Campbell, David Gallego-Ortega, Jeffry Evans, Owen J. Sansom, Jennifer P. Morton, Kurt I. Anderson, Paul Timpson. A biosensor mouse to predict the dissociation and spread of pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Engineering and Physical Sciences in Oncology; 2016 Jun 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2017;77(2 Suppl):Abstract nr PR07.

Objective: To describe 2 cases of clinically significant phenytoin removal during continuous venovenous hemofiltration (CVVH) and review the relevant literature regarding phenytoin removal by renal replacement modalities. Case Summary: A 64-year-old female with chronic kidney disease and cirrhosis was admitted to the intensive care unit (ICU) with a traumatic subdural hematoma and seizures. The patient received a loading dose of intravenous phenytoin 1000 mg, followed by maintenance intravenous administration of phenytoin 100 mg and levetiracetam 250 mg every 12 hours. CVVH was initiated for acidosis. A 63-year-old male was admitted to the ICU after cardiac surgery complicated by hypotension. CVVH was initiated for fluid overload, and phenytoin was initiated 3 days later for seizures. A loading dose of intravenous phenytoin 2700 mg was administered, followed by maintenance dosing of intravenous phenytoin 150 mg every 8 hours. Concentrations of unbound phenytoin in serum and CVVH effluent samples were measured during concomitant treatment in each patient. In both patients, serum and effluent concentrations of unbound phenytoin fell steadily while they were on CVVH. Clearance of phenytoin by CVVH was calculated, as was the daily removal of phenytoin, as a percentage of total daily phenytoin dosage during each sampling period. Phenytoin clearance by CVVH ranged from 11 to 13 mL/min in these patients. Discussion: The clearance of phenytoin with CVVH in these 2 patients was much higher than the renal clearance of phenytoin reported in healthy volunteers with normal renal function. Previous case reports have demonstrated that only small, clinically insignificant amounts of phenytoin are removed by hemodialysis, and the only published report of phenytoin removal by continuous renal replacement therapy used hemofiltration rates much lower than those used in the 2 cases described here. Conclusions: These cases demonstrate that a substantial amount—approximately 30%—of total daily phenytoin dose may be removed by CVVH, and patients may require higher than expected empiric doses. Phenytoin concentrations should be closely monitored in critically ill patients receiving CVVH.

A generally accepted objective measure for listening effort in hearing aid fitting procedures is still missing. Thus, the focus of our research is the extraction of possible neural correlates of listening effort by using electroencephalographic data. Such an objective measure could optimize the hearing aid fitting procedures by reducing the listening effort in hearing aid wearers. In the current study, we tested different hearing aid configurations in 15 normal hearing persons. For this, we created a realistic listening situation using standardized sentences embedded in multitalker babble noise at a fixed signal to noise ratio. The main objectives were (i) to extract possible neural correlates of listening effort using the previously proposed angular entropy measure; (ii) to find the respective electrode locations and scales (frequencies) which best represent the subjectively rated listening effort. In order to decompose the multiway data (electrode channel × number of sentences × scales) the parallel factor analysis (PARAFAC) was applied to the ANOVA F-test values. The results indicate that the refined angular entropy could serve as a possible correlate of listening effort in frontal electrode locations in the frequency range of the EEG theta band. Anyway further research is necessary to validate these findings.

Successful auditory stream segregation depends on correctly inhibiting irrelevant stimuli being perceived in parallel with relevant information. Here, we analyze the behavioral correlates of inhibitory processing in healthy subjects, by first calculating the percentage of inhibition elicited through a paired-chirp auditory stimulation paradigm and then analyzing its correlation to the score in a speech intelligibility task. Analysis of cortical inhibition was made both in amplitude and phase, focusing on the N1-P2 complex. Significant inhibition between the condition and the test chirp in both of the inter stimulus intervals (ISIs) used and both N1 and P2 waves was observed. Inhibition in phase synchronization stability (PSS) showed a positive correlation to scores obtained in the task for all given modalities of the study, while amplitude analysis showed a correlation for the N1 wave with 500 ms ISI only. It was shown that the PSS analysis provides a more reliable representation of cortical inhibition, able to correlate to the attentional task. It is concluded that the given paradigm allows to assess inhibitory processing, vital to the allocation of attention.

Multidrug-resistant pathogens have become increasingly common in contemporary healthcare. Specific to Gram-positive pathogens, methicillin-resistant Staphylococcus aureus (MRSA) is of particular concern, as it has been associated with increased hospital length of stay, higher healthcare expenditures and poorer outcomes. To date, linezolid is the first and only oxazolidinone approved by the US FDA for the treatment of infections caused by Gram-positive pathogens, including MRSA. This article will serve as a comprehensive review of linezolid, including an overview of the current market and its in vitro activity, with an in-depth review of its pharmacokinetic and pharmacodynamic profile. Emphasis will be placed on clinical data for the drug, both on- and off-label. The article will conclude with a brief overview of linezolid’s pharmacoeconomic implications and safety profile, followed by a commentary and 5-year prospective analysis remarking on the future of the antimicrobial field as it relates to MRSA.

During pregnancy, the ETS transcription factor ELF5 establishes the milk-secreting alveolar cell lineage by driving a cell fate decision of the mammary luminal progenitor cell. In breast cancer, ELF5 is a key transcriptional determinant of tumor subtype and has been implicated in the development of insensitivity to anti-estrogen therapy. In the mouse mammary tumor virus-Polyoma Middle T (MMTV-PyMT) model of luminal breast cancer, induction of ELF5 levels increased leukocyte infiltration, angiogenesis, and blood vessel permeability in primary tumors and greatly increased the size and number of lung metastasis. Myeloid-derived suppressor cells, a group of immature neutrophils recently identified as mediators of vasculogenesis and metastasis, were recruited to the tumor in response to ELF5. Depletion of these cells using specific Ly6G antibodies prevented ELF5 from driving vasculogenesis and metastasis. Expression signatures in luminal A breast cancers indicated that increased myeloid cell invasion and inflammation were correlated with ELF5 expression, and increased ELF5 immunohistochemical staining predicted much shorter metastasis–free and overall survival of luminal A patients, defining a group who experienced unexpectedly early disease progression. Thus, in the MMTV-PyMT mouse mammary model, increased ELF5 levels drive metastasis by co-opting the innate immune system. As ELF5 has been previously implicated in the development of antiestrogen resistance, this finding implicates ELF5 as a defining factor in the acquisition of the key aspects of the lethal phenotype in luminal A breast cancer., Up-regulation of the transcription factor ELF5 in tumors helps to create a micro-environment that recruits the innate immune system and increases vascular permeability, leading to increased metastasis in luminal breast cancer. Together with its role in anti-estrogen resistance, this suggests that ELF5 is a major driver of a lethal phenotype., Author Summary The transcription factor Elf5 defines hormone-insensitive and endocrine-therapy–resistant breast cancer. In this study, we have discovered that ELF5 drives the spread of tumor cells to the lungs. We demonstrate that the underlying mechanism for this metastatic spread is via recruitment of the innate immune system. Interestingly, this effect is able to overcome the other tumor-suppressive effects of ELF5 on cancer cells, such as reduced proliferation, motility, and invasion. This important finding challenges the more conventional view that the most potent determinant of metastatic activity lies within the cancer cell. We clearly demonstrate that the innate immune system strongly influences the metastatic activity of cancer cells despite their cell-intrinsic spread potential. Our previous work demonstrated that in luminal breast cancer, ELF5 is a key determinant of antiestrogen therapy resistance. Here, we show that the metastatic mechanism driven by ELF5 is most important in luminal breast cancer patients, in whom higher ELF5 expression is associated with low presence of cytotoxic T lymphocytes, an immune cell population responsible for tumor rejection. Thus, we now see that ELF5 may be behind the two most important processes that cause luminal breast cancers to progress towards the lethal phenotype; resistance to antiestrogen therapy and the development of metastatic activity. This understanding could pave the way for new therapeutic strategies to be devised and new predictive tests to be developed.