Targeting NF-κB signaling in B cells as a potential new treatment modality for ANCA-associated vasculitis

B lineage cells are critically involved in ANCA-associated vasculitis (AAV), evidenced by alterations in circulating B cell subsets and beneficial clinical effects of rituximab (anti-CD20) therapy. This treatment renders a long-term, peripheral B cell depletion, but allows for the survival of long-lived plasma cells. Therefore, there is an unmet need for more reversible and full B lineage cell targeting approaches. To find potential novel therapeutic targets, RNA sequencing of CD27+ memory B cells of patients with active AAV was performed, revealing an upregulated NF-κB-associated gene signature. NF-κB signaling pathways act downstream of various B cell surface receptors, including the BCR, CD40, BAFFR and TLRs, and are essential for B cell responses. Here we demonstrate that novel pharmacological inhibitors of NF-κB inducing kinase (NIK, non-canonical NF-κB signaling) and inhibitor-of-κB-kinase-β (IKKβ, canonical NF-κB signaling) can effectively inhibit NF-κB signaling in B cells, whereas T cell responses were largely unaffected. Moreover, both inhibitors significantly reduced B cell proliferation, differentiation and production of antibodies, including proteinase-3 (PR3) autoantibodies, in B lineage cells of AAV patients. These findings indicate that targeting NF-κB, particularly NIK, may be an effective, novel B lineage cell targeted therapy for AAV and other autoimmune diseases with prominent B cell involvement.

Gymnotic uptake of AntimiRs alter microRNA-34a levels in 2D and 3D epithelial cell culture

MicroRNAs are attractive therapeutic targets in many diseases, including chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis. Among microRNA inhibitors antimiRs have been proven successful in lowering aberrant microRNA levels in the clinic. We present a set of antimiRs targeting miR-34a, which has been shown to be dysregulated in chronic lung diseases. The tool compounds were taken up by a bronchial epithelial cell line and primary human bronchial epithelial cells, followed by efficient knockdown of miR-34a. Similar results were observed in 3D differentiated primary human bronchial epithelial cells cultured at the air-liquid interface. Varying chemical properties of antimiRs had significant impact on cellular uptake and potency, resulting in effective tool compounds for use in lung-relevant cellular systems. This report demonstrates gymnotic antimiR uptake and activity in 3D epithelial cell culture after apical administration, mimicking inhalation conditions.

Cohort profile: The Swedish Tattoo and Body Modifications Cohort (TABOO)

PURPOSE

The Swedish Tattoo and Body Modifications Cohort (TABOO) cohort was established to provide an infrastructure for epidemiological studies researching the role of tattoos and other body modifications as risk factors for adverse health outcomes. It is the first population-based cohort with detailed exposure assessment of decorative, cosmetic, and medical tattoos, piercing, scarification, henna tattoos, cosmetic laser treatments, hair dyeing, and sun habits. The level of detail in the exposure assessment of tattoos allows for investigation of crude dose-response relationships.

PARTICIPANTS

The TABOO cohort includes 13 049 individuals that participated in a questionnaire survey conducted in 2021 (response rate 49%). Outcome data are retrieved from the National Patient Register, the National Prescribed Drug Register and the National Cause of Death Register. Participation in the registers is regulated by Swedish law, which eliminates the risk of loss to follow-up and associated selection bias.

FINDINGS TO DATE

The tattoo prevalence in TABOO is 21%. The cohort is currently used to clarify the incidence of acute and long-lasting health complaints after tattooing based on self-reported data. Using register-based outcome data, we are investigating the role of tattoos as a risk factor for immune-mediated disease, including hypersensitisation, foreign body reactions and autoimmune conditions.

FUTURE PLANS

The register linkage will be renewed every third year to update the outcome data, and we have ethical approval to reapproach the responders with additional questionnaires.

A21 ROLE OF SIALIC ACID O-ACETYLATION IN MAINTAINING MUCUS INTEGRITY AND HOMEOSTASIS OF THE COLONIC MUCOSA

Background

The mucus network provides innate immune defense to protect our gastrointestinal tract from pathogens, and promote homeostasis with our resident microbiota. This network is constituted by the mucin MUC2 (Muc2 in mouse), which is ~80% complex O-linked glycans by weight. Sialic acid (Sia) is a key capping monosaccharide on complex O-glycans which has recently been linked to preserving mucus integrity. Sia can undergo enzymatic modifications including the addition of O-acetyl groups. The 9-O-acetyltransferase CasD1 is responsible for the 9-OAc Sia variants. Functionally, the OAc-modification is known to inhibit microbial sialidase activities which may preserve Sia’s protective roles on mucins. However, the extent of these OAc modifications in human and murine Mucin-2, and how they influence mucus function is unclear.

Purpose: To determine whether and how Sia O-acetylation on colonic mucus regulates mucus integrity, host-microbe interactions, and colitis susceptibility.

Method

We used viral-derived probes that target specific OAc-Sia analogues on mucus on sections from human feces and mouse feces and colon tissues to visualize their spatial arrangement and microbial interaction in situ. For glycomics, OAc-Sia analogues were quantitated on purified human MUC2 and mouse Muc2 by HPLC-MS after derivatization with 4,5-dimethyl-1,2-diaminobenzamine (DMBA). O-glycans were released via non-reductive ammonia-catalyzed β-elimination and analyzed by mass spectrometry. For in vivo work, we generated intestinal epithelial cell-specific Casd1 KO mice (Casd1^flox/flox;VillinCre or IEC Casd1^-/- mice) and analyzed their mucins. Sialidase activities were quantified in the supernatants of colon fecal materials from WT and IEC Casd1^-/- mutants mice using a fluorogenic substrate 4-MU-NeuNAc. Colitis susceptibility was monitored using 1.5% w/v Dextran Sodium Sulfate (DSS).

Result(s)

We found Sias on both human MUC2 and murine Muc2 were heavily O-acetylated, with ~75% and ~45% of Sias having 9-OAc-based modification in humans and mice respectively, and were distributed throughout the niche and barrier layers of mucus in situ. IEC Casd1^-/- mice were viable and healthy with knockdown confirmed by 9-OAc staining, western blot of protein lysates and mucins, and sialylomics. The mucus encapsulation appeared overall intact regardless of OAc status. However, IEC Casd1^-/- mice showed heightened susceptibility to 1.5% DSS colitis, linked to thinning of the mucus in IEC Casd1^-/- vs WT littermates after challenge. Consistent with the role of OAc Sia in sialidase inhibition, loss of OAc Sia was associated with increased sialidase activities as assessed by heightened 4 MU signal in fecal supernatants in WT vs littermate IEC Casd1^-/- mice. O-glycomics also showed reduction in the number of sialylated O-glycan structures upon loss of 9-OAc Sia.

Conclusion(s)

Sia O-acetylation appears important in maintaining key aspects of Sia-dependent mucus function and protecting from inflammatory insult.

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Disclosure of Interest

None Declared

Non-heme iron overload impairs monocyte to macrophage differentiation via mitochondrial oxidative stress

Iron is a key element for systemic oxygen delivery and cellular energy metabolism. Thus regulation of systemic and local iron metabolism is key for maintaining energy homeostasis. Significant changes in iron levels due to malnutrition or hemorrhage, have been associated with several diseases such as hemochromatosis, liver cirrhosis and COPD. Macrophages are key cells in regulating iron levels in tissues as they sequester excess iron. How iron overload affects macrophage differentiation and function remains a subject of debate. Here we used an in vitro model of monocyte-to-macrophage differentiation to study the effect of iron overload on macrophage function. We found that providing excess iron as soluble ferric ammonium citrate (FAC) rather than as heme-iron complexes derived from stressed red blood cells (sRBC) interferes with macrophage differentiation and phagocytosis. Impaired macrophage differentiation coincided with increased expression of oxidative stress-related genes. Addition of FAC also led to increased levels of cellular and mitochondrial reactive oxygen species (ROS) and interfered with mitochondrial function and ATP generation. The effects of iron overload were reproduced by the mitochondrial ROS-inducer rotenone while treatment with the ROS-scavenger N-Acetylcysteine partially reversed FAC-induced effects. Finally, we found that iron-induced oxidative stress interfered with upregulation of M-CSFR and MAFB, two crucial determinants of macrophage differentiation and function. In summary, our findings suggest that high levels of non-heme iron interfere with macrophage differentiation by inducing mitochondrial oxidative stress. These findings might be important to consider in the context of diseases like chronic obstructive pulmonary disease (COPD) where both iron overload and defective macrophage function have been suggested to play a role in disease pathogenesis.

Urinary metabotype of severe asthma evidences decreased carnitine metabolism independent of oral corticosteroid treatment in the U-BIOPRED study

INTRODUCTION

Asthma is a heterogeneous disease with poorly defined phenotypes. Severe asthmatics often receive multiple treatments including oral corticosteroids (OCS). Treatment may modify the observed metabotype, rendering it challenging to investigate underlying disease mechanisms. Here, we aimed to identify dysregulated metabolic processes in relation to asthma severity and medication.

METHODS

Baseline urine was collected prospectively from healthy participants (n=100), mild-to-moderate asthmatics (n=87) and severe asthmatics (n=418) in the cross-sectional U-BIOPRED cohort; 12-18-month longitudinal samples were collected from severe asthmatics (n=305). Metabolomics data were acquired using high-resolution mass spectrometry and analysed using univariate and multivariate methods.

RESULTS

Ninety metabolites were identified, with 40 significantly altered (p<0.05, FDR<0.05) in severe asthma and 23 by OCS use. Multivariate modelling showed that observed metabotypes in healthy participants and mild-to-moderate asthmatics differed significantly from severe asthmatics (p=2.6×10^-20), OCS-treated asthmatics differed significantly from non-treated (p=9.5×10^-4), and longitudinal metabotypes demonstrated temporal stability. Carnitine levels evidenced the strongest OCS-independent decrease in severe asthma. Reduced carnitine levels were associated with mitochondrial dysfunction via decreases in pathway enrichment scores of fatty acid metabolism and reduced expression of the carnitine transporter SLC22A5 in sputum and bronchial brushings.

CONCLUSIONS

This is the first large-scale study to delineate disease- and OCS-associated metabolic differences in asthma. The widespread associations with different therapies upon the observed metabotypes demonstrate the necessity to evaluate potential modulating effects on a treatment- and metabolite-specific basis. Altered carnitine metabolism is a potentially actionable therapeutic target that is independent of OCS treatment, highlighting the role of mitochondrial dysfunction in severe asthma.

Identification of a missense variant in SPDL1 associated with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disorder characterised by progressive, destructive lung scarring. Despite substantial progress, the genetic determinants of this disease remain incompletely defined. Using whole genome and whole exome sequencing data from 752 individuals with sporadic IPF and 119,055 UK Biobank controls, we performed a variant-level exome-wide association study (ExWAS) and gene-level collapsing analyses. Our variant-level analysis revealed a novel association between a rare missense variant in SPDL1 and IPF (NM_017785.5:g.169588475 G > A p.Arg20Gln; p = 2.4 × 10-7, odds ratio = 2.87, 95% confidence interval: 2.03-4.07). This signal was independently replicated in the FinnGen cohort, which contains 1028 cases and 196,986 controls (combined p = 2.2 × 10-20), firmly associating this variant as an IPF risk allele. SPDL1 encodes Spindly, a protein involved in mitotic checkpoint signalling during cell division that has not been previously described in fibrosis. To the best of our knowledge, these results highlight a novel mechanism underlying IPF, providing the potential for new therapeutic discoveries in a disease of great unmet need.

Association of coronary calcium score with endothelial dysfunction and arterial stiffness

BACKGROUND AND AIMS

The aim of the study was to determine potential associations between endothelial dysfunction and arterial stiffness, measured by peripheral arterial tonometry, and coronary artery calcium score (CACS) assessed by computed tomography (CT).

METHODS AND RESULTS

The BIG3 study is a prospective longitudinal, non-interventional, pulmonary-cardiovascular cohort study exploring the three major smoking-induced diseases: cardiovascular disease, chronic obstructive pulmonary disease, and lung cancer, in a 45-75 aged cohort (mean 62 years), enriched in smokers. Computed tomography of the chest with assessment of CACS was performed in a selected subset of the participants (n = 2080). Peripheral arterial tonometry (EndoPAT) was used to assess endothelial function and arterial stiffness measured as reactive hyperaemia index (RHI) and augmentation index (AI), respectively. We observed significant associations of CACS, endothelial dysfunction, and arterial stiffness with several risk factors for coronary heart disease including age, sex, BMI, diabetes mellitus, and blood pressure. There was significant association of CACS, classified into three levels of severity, with RHI and AI (p = 0.0005 and p = 0.0009, respectively). For groups of increasing CACS (0, 1-400 and > 400 Agatston score), RHI decreased from median 1.89 (1.58-2.39), and 1.93 (1.62-2.41) to 1.77 (1.51-2.10). AI increased from median 14.3 (5.7-25.2), and 16.4 (8.1-27.6) to 18.0 (9.1-29.2). RHI, but not AI, remained significantly associated with CACS after risk factors adjustment.

CONCLUSIONS

In this large study of coronary artery calcium and vascular function, we found an association between CACS and both endothelial dysfunction and arterial stiffness, indicating that they may reflect similar mechanisms for development of cardiovascular disease.

A new house dust mite-driven and mast cell-activated model of asthma in the guinea pig

BACKGROUND

Animal models are extensively used to study underlying mechanisms in asthma. Guinea pigs share anatomical, pharmacological and physiological features with human airways and may enable the development of a pre-clinical in vivo model that closely resembles asthma.

OBJECTIVES

To develop an asthma model in guinea pigs using the allergen house dust mite (HDM).

METHODS

Guinea pigs were intranasally sensitized to HDM which was followed by HDM challenges once weekly for five weeks. Antigen-induced bronchoconstriction (AIB) was evaluated as alterations in R_n (Newtonian resistance), G (tissue damping) and H (tissue elastance) at the first challenge with forced oscillation technique (FOT), and changes in respiratory pattern upon each HDM challenge were assessed as enhanced pause (Penh) using whole-body plethysmography. Airway responsiveness to methacholine was measured one day after the last challenge by FOT. Inflammatory cells and cytokines were quantified in bronchoalveolar lavage fluid, and HDM-specific immunoglobulins were measured in serum by ELISA. Airway pathology was evaluated by conventional histology.

RESULTS

The first HDM challenge after the sensitization generated a marked increase in R_n and G, which was abolished by pharmacological inhibition of histamine, leukotrienes and prostanoids. Repeated weekly challenges of HDM caused increase of Penh and a marked increase in airway hyperresponsiveness for all three lung parameters (R_n , G and H) and eosinophilia. Levels of IgE, IgG₁ , IgG₂ and IL-13 were elevated in HDM-treated guinea pigs. HDM exposure induced infiltration of inflammatory cells into the airways with a pronounced increase of mast cells. Subepithelial collagen deposition, airway wall thickness and goblet cell hyperplasia were induced by repeated HDM challenge.

CONCLUSION AND CLINICAL RELEVANCE

Repeated intranasal HDM administration induces mast cell activation and hyperplasia together with an asthma-like pathophysiology in guinea pigs. This model may be suitable for mechanistic investigations of asthma, including evaluation of the role of mast cells.

T2 and T17 cytokines alter the cargo and function of airway epithelium-derived extracellular vesicles

Background

Asthma is a common and heterogeneous disease that includes subgroups characterized by type 2 (T2) or type 17 (T17) immune responses for which there is a need to identify the underlying mechanisms and biomarkers in order to develop specific therapies. These subgroups can be defined by airway epithelium gene signatures and the airway epithelium has also been implicated to play a significant role in asthma pathology. Extracellular vesicles (EVs) carry functional biomolecules and participate in cell-to-cell communication in both health and disease, properties that are likely to be involved in airway diseases such as asthma. The aim of this study was to identify stimulus-specific proteins and functionality of bronchial epithelium-derived EVs following stimulation with T2 or T17 cytokines.

Methods

EVs from cytokine-stimulated (T2: IL-4 + IL-13 or T17: IL-17A + TNFα) human bronchial epithelial cells cultured at air-liquid interface (HBEC-ALI) were isolated by density cushion centrifugation and size exclusion chromatography and characterized with Western blotting and electron microscopy. Transcriptomic (cells) and proteomic (EVs) profiling was also performed.

Results

Our data shows that EVs are secreted and can be isolated from the apical side of HBEC-ALI and that cytokine stimulation increases EV release. Genes upregulated in cells stimulated with T2 or T17 cytokines were increased also on protein level in the EVs. Proteins found in T17-derived EVs were suggested to be involved in pathways related to neutrophil movement which was supported by assessing neutrophil chemotaxis ex vivo.

Conclusions

Together, the results suggest that epithelial EVs are involved in airway inflammation and that the EV proteome may be used for discovery of disease-specific mechanisms and signatures which may enable a precision medicine approach to the treatment of asthma.

ToF-SIMS mediated analysis of human lung tissue reveals increased iron deposition in COPD (GOLD IV) patients

Chronic obstructive pulmonary disease (COPD) is a debilitating lung disease that is currently the third leading cause of death worldwide. Recent reports have indicated that dysfunctional iron handling in the lungs of COPD patients may be one contributing factor. However, a number of these studies have been limited to the qualitative assessment of iron levels through histochemical staining or to the expression levels of iron-carrier proteins in cells or bronchoalveolar lavage fluid. In this study, we have used time of flight secondary ion mass spectrometry (ToF-SIMS) to visualize and relatively quantify iron accumulation in lung tissue sections of healthy donors versus severe COPD patients. An IONTOF 5 instrument was used to perform the analysis, and further multivariate analysis was used to analyze the data. An orthogonal partial least squares discriminant analysis (OPLS-DA) score plot revealed good separation between the two groups. This separation was primarily attributed to differences in iron content, as well as differences in other chemical signals possibly associated with lipid species. Further, relative quantitative analysis revealed twelve times higher iron levels in lung tissue sections of COPD patients when compared to healthy donors. In addition, iron accumulation observed within the cells was heterogeneously distributed, indicating cellular compartmentalization.

A Disintegrin and Metalloproteinase Domain-8: A Novel Protective Proteinase in Chronic Obstructive Pulmonary Disease

RATIONALE

ADAM8 (a disintegrin and metalloproteinase domain-8) is expressed by leukocytes and epithelial cells in health, but its contribution to the pathogenesis of chronic obstructive pulmonary disease (COPD) is unknown.

OBJECTIVES

To determine whether the expression of ADAM8 is increased in the lungs of patients with COPD and cigarette smoke (CS)-exposed mice, and whether ADAM8 promotes the development of COPD.

METHODS

ADAM8 levels were measured in lung, sputum, plasma, and/or BAL fluid samples from patients with COPD, smokers, and nonsmokers, and wild-type (WT) mice exposed to CS versus air. COPD-like lung pathologies were compared in CS-exposed WT versus Adam8-/- mice.

MEASUREMENTS AND MAIN RESULTS

ADAM8 immunostaining was reduced in macrophages, and alveolar and bronchial epithelial cells in the lungs of patients with COPD versus control subjects, and CS- versus air-exposed WT mice. ADAM8 levels were similar in plasma, sputum, and BAL fluid samples from patients with COPD and control subjects. CS-exposed Adam8-/- mice had greater airspace enlargement and airway mucus cell metaplasia than WT mice, but similar small airway fibrosis. CS-exposed Adam8-/- mice had higher lung macrophage counts, oxidative stress levels, and alveolar septal cell death rates, but lower alveolar septal cell proliferation rates and soluble epidermal growth factor receptor BAL fluid levels than WT mice. Adam8 deficiency increased lung inflammation by reducing CS-induced activation of the intrinsic apoptosis pathway in macrophages. Human ADAM8 proteolytically shed the epidermal growth factor receptor from bronchial epithelial cells to reduce mucin expression in vitro. Adam8 bone marrow chimera studies revealed that Adam8 deficiency in leukocytes and lung parenchymal cells contributed to the exaggerated COPD-like disease in Adam8-/- mice.

CONCLUSIONS

Adam8 deficiency increases CS-induced lung inflammation, emphysema, and airway mucus cell metaplasia. Strategies that increase or prolong ADAM8's expression in the lung may have therapeutic efficacy in COPD.

Epithelial IL-6 trans-signaling defines a new asthma phenotype with increased airway inflammation

BACKGROUND

Although several studies link high levels of IL-6 and soluble IL-6 receptor (sIL-6R) to asthma severity and decreased lung function, the role of IL-6 trans-signaling (IL-6TS) in asthmatic patients is unclear.

OBJECTIVE

We sought to explore the association between epithelial IL-6TS pathway activation and molecular and clinical phenotypes in asthmatic patients.

METHODS

An IL-6TS gene signature obtained from air-liquid interface cultures of human bronchial epithelial cells stimulated with IL-6 and sIL-6R was used to stratify lung epithelial transcriptomic data (Unbiased Biomarkers in Prediction of Respiratory Disease Outcomes [U-BIOPRED] cohorts) by means of hierarchical clustering. IL-6TS-specific protein markers were used to stratify sputum biomarker data (Wessex cohort). Molecular phenotyping was based on transcriptional profiling of epithelial brushings, pathway analysis, and immunohistochemical analysis of bronchial biopsy specimens.

RESULTS

Activation of IL-6TS in air-liquid interface cultures reduced epithelial integrity and induced a specific gene signature enriched in genes associated with airway remodeling. The IL-6TS signature identified a subset of patients with IL-6TS-high asthma with increased epithelial expression of IL-6TS-inducible genes in the absence of systemic inflammation. The IL-6TS-high subset had an overrepresentation of frequent exacerbators, blood eosinophilia, and submucosal infiltration of T cells and macrophages. In bronchial brushings Toll-like receptor pathway genes were upregulated, whereas expression of cell junction genes was reduced. Sputum sIL-6R and IL-6 levels correlated with sputum markers of remodeling and innate immune activation, in particular YKL-40, matrix metalloproteinase 3, macrophage inflammatory protein 1β, IL-8, and IL-1β.

CONCLUSIONS

Local lung epithelial IL-6TS activation in the absence of type 2 airway inflammation defines a novel subset of asthmatic patients and might drive airway inflammation and epithelial dysfunction in these patients.

A Disintegrin and A Metalloproteinase-9 (ADAM9): A Novel Proteinase Culprit with Multifarious Contributions to COPD

INTRODUCTION

Proteinases with a disintegrin and a metalloproteinase domain (ADAMs) have not been well studied in COPD. We investigated whether ADAM9 is linked to COPD in humans and mice.

METHODS

ADAM9 blood and lung levels were measured in COPD patients versus controls, and air- versus cigarette smoke (CS)-exposed wild-type (WT) mice. WT and Adam9-/- mice were exposed to air or CS for 1-6 months, and COPD-like lung pathologies were measured.

RESULTS

ADAM9 staining was increased in lung epithelial cells and macrophages in smokers and even more so in COPD patients and correlated directly with pack-year smoking history and inversely with airflow obstruction and/or FEV1 % predicted. Bronchial epithelial cell ADAM9 mRNA levels were higher in COPD patients than controls and correlated directly with pack-year smoking history. Plasma, BALF and sputum ADAM9 levels were similar in COPD patients and controls. CS exposure increased Adam9 levels in WT murine lungs. Adam9-/- mice were protected from emphysema development, small airway fibrosis, and airway mucus metaplasia. CS-exposed Adam9-/- mice had reduced lung macrophage counts, alveolar septal cell apoptosis, lung elastin degradation, and shedding of VEGFR2 and EGFR in BALF samples. Recombinant ADAM9 sheds EGF and VEGF receptors from epithelial cells to reduce activation of the Akt pro-survival pathway and increase cellular apoptosis.

CONCLUSIONS

ADAM9 levels are increased in COPD lungs and linked to key clinical variables. Adam9 promotes emphysema development, and large and small airway disease in mice. Inhibition of ADAM9 could be a therapeutic approach for multiple COPD phenotypes.

Depression or anxiety in adult twins is associated with asthma diagnosis but not with offspring asthma

BACKGROUND

Asthma is common in both children and adults in the Western world, just like anxiety and depression. While some research has revealed that these diseases might share important environmental and pathophysiological aspects, the exact mechanisms still remain unclear.

OBJECTIVE

To study the correlation firstly between depression or anxiety and asthma diagnosis in adult twins and secondly the association between parental depression or anxiety and offspring asthma in children of twins.

METHODS

In total, 24 685 adult twins aged 20-47 years were interviewed or completed a Web-based questionnaire and their children were identified through the Multi-Generation Register. Asthma diagnosis was obtained from the Patient Register and the Prescribed Drug Register. Assessment of depression and anxiety was obtained from questionnaires using Center for Epidemiologic Studies Depression Scale (CES-D), major depression and generalized anxiety disorder (GAD) from DSM-IV. The association between depression or anxiety and asthma was analyzed with logistic regression adjusting for confounders in twins and offspring. To address genetic and familial environmental confounding, we performed a cotwin analysis using disease-discordant twin pairs.

RESULTS

We found an association between asthma and CES-D, major depression and GAD, for example adjusted OR for major depression and register-based asthma 1.56 (1.36-1.79). Most of the point estimates remained in the co-twin control analysis, indicating that the association was likely not due to genetic or familial environmental factors. There was no association between parental depression and/or anxiety and asthma diagnosis in the offspring which implies lack of genetic confounding.

CONCLUSIONS

We found an association between own asthma diagnosis and anxiety or depression, but not with offspring asthma. Our results indicate that the associations were not due to confounding from genes or environment shared by the twins.

Abstract P5-08-09: Use of oral contraceptives and risk of breast cancer in BRCA1 and BRCA2 mutation carriers: An international prospective cohort study; for the studies of EMBRACE, GENEPSO, HEBON, kConFab and BCFR

This abstract was withdrawn by the authors.

Targeting non-canonical nuclear factor-κB signalling attenuates neovascularization in a novel 3D model of rheumatoid arthritis synovial angiogenesis

OBJECTIVE

Angiogenesis is crucial in RA disease progression. Lymphotoxin β receptor (LTβR)-induced activation of the non-canonical nuclear factor-κB (NF-κB) pathway via NF-κB-inducing kinase (NIK) has been implicated in this process. Consequently, inhibition of this pathway may hold therapeutic potential in RA. We describe a novel three-dimensional (3D) model of synovial angiogenesis incorporating endothelial cells (ECs), RA fibroblast-like synoviocytes (RAFLSs) and RA synovial fluid (RASF) to further investigate the contributions of NF-κB in this process.

METHODS

Spheroids consisting of RAFLSs and ECs were stimulated with RASF, the LTβR ligands LTβ and LIGHT, or growth factor bFGF and VEGF, followed by quantification of EC sprouting using confocal microscopy and digital image analysis. Next, the effects of anginex, NIK-targeting siRNA (siNIK), LTβR-Ig fusion protein (baminercept) and a novel pharmacological NIK inhibitor were investigated.

RESULTS

RASF significantly promoted sprout formation, which was blocked by the established angiogenesis inhibitor anginex (P < 0.05). LTβ and LIGHT induced significant sprouting (P < 0.05), as did bFGF/VEGF (P < 0.01). siNIK pre-treatment of ECs led to reductions in LTβR-induced vessel formation (P < 0.05). LTβR-Ig not only blocked LTβ- or LIGHT-induced sprouting, but also RASF-induced sprouting (P < 0.05). The NIK inhibitor blocked angiogenesis induced by LTβ, LIGHT, growth factors (P < 0.05) and RASF (P < 0.01).

CONCLUSION

We present a novel 3D model of synovial angiogenesis incorporating RAFLSs, ECs and RASF that mimics the in vivo situation. Using this system, we demonstrate that non-canonical NF-κB signalling promotes neovascularization and show that this model is useful for dissecting relative contributions of signalling pathways in specific cell types to angiogenic responses and for testing pharmacological inhibitors of angiogenesis.

Risk of second primary cancer in patients treated with radiotherapy for rectal cancer

BACKGROUND

Many patients with rectal cancer receive radiotherapy (RT) to reduce the risk of local recurrence. Radiation may give rise to adverse effects, including second primary cancers. In view of the divergent results of previous studies, the present study evaluated the risk of second primary cancer following RT in all randomized RT rectal cancer trials conducted in Sweden and in the Swedish ColoRectal Cancer Registry (SCRCR).

METHODS

Patients included in five randomized trials and the SCRCR were linked to the Swedish Cancer Registry. Cox regression models estimated the hazard ratio (HR) of second primary cancer among patients who received RT compared with those who did not.

RESULTS

A total of 13 457 patients were included in this study; 7024 (52·2 per cent) received RT and 6433 (47·8 per cent) had surgery alone. Overall, no increased risk of second primary cancer was observed with RT (HR 1·03; 95 per cent c.i. 0·92 to 1·15), independently of follow-up time and location within or outside of the irradiated volume. In the randomized trials, with longer follow-up (maximum 31 years), a slight increase was observed outside of (HR 1·33, 1·01 to 1·74) but not within (HR 1·11, 0·73 to 1·67) the irradiated volume. Irradiated men had a lower risk of prostate cancer than those treated with surgery alone (HR 0·68, 0·51 to 0·91).

CONCLUSION

Overall, there was no increased risk of second primary cancer following RT for rectal cancer within or outside of the irradiated volume up to 20 years of follow-up. Men with rectal cancer who received RT had a reduced risk of prostate cancer.

Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort

OBJECTIVE

Women with active sunlight exposure habits experience a lower mortality rate than women who avoid sun exposure; however, they are at an increased risk of skin cancer. We aimed to explore the differences in main causes of death according to sun exposure.

METHODS

We assessed the differences in sun exposure as a risk factor for all-cause mortality in a competing risk scenario for 29 518 Swedish women in a prospective 20-year follow-up of the Melanoma in Southern Sweden (MISS) cohort. Women were recruited from 1990 to 1992 (aged 25-64 years at the start of the study). We obtained detailed information at baseline on sun exposure habits and potential confounders. The data were analysed using modern survival statistics.

RESULTS

Women with active sun exposure habits were mainly at a lower risk of cardiovascular disease (CVD) and noncancer/non-CVD death as compared to those who avoided sun exposure. As a result of their increased survival, the relative contribution of cancer death increased in these women. Nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group, indicating that avoidance of sun exposure is a risk factor for death of a similar magnitude as smoking. Compared to the highest sun exposure group, life expectancy of avoiders of sun exposure was reduced by 0.6-2.1 years.

CONCLUSION

The longer life expectancy amongst women with active sun exposure habits was related to a decrease in CVD and noncancer/non-CVD mortality, causing the relative contribution of death due to cancer to increase.

St Gallen molecular subtypes in screening-detected and symptomatic breast cancer in a prospective cohort with long-term follow-up

Background

Diagnosis by screening mammography is considered an independent positive prognostic factor, although the data are not fully in agreement. The aim of the study was to explore whether the mode of detection (screening‐detected versus symptomatic) adds prognostic information to the St Gallen molecular subtypes of primary breast cancer, in terms of 10‐year cumulative breast cancer mortality (BCM).

Methods

A prospective cohort of patients with primary breast cancer, who had regularly been invited to screening mammography, were included. Tissue microarrays were constructed from primary tumours and lymph node metastases, and evaluated by two independent pathologists. Primary tumours and lymph node metastases were classified into St Gallen molecular subtypes. Cause of death was retrieved from the Central Statistics Office.

Results

A total of 434 patients with primary breast cancer were included in the study. Some 370 primary tumours and 111 lymph node metastases were classified into St Gallen molecular subtypes. The luminal A‐like subtype was more common among the screening‐detected primary tumours (P = 0·035) and corresponding lymph node metastases (P = 0·114) than among symptomatic cancers. Patients with screening‐detected tumours had a lower BCM (P = 0·017), and for those diagnosed with luminal A‐like tumours the 10‐year cumulative BCM was 3 per cent. For patients with luminal A‐like lymph node metastases, there was no BCM. In a stepwise multivariable analysis, the prognostic information yielded by screening detection was hampered by stage and tumour biology.

Conclusion

The prognosis was excellent for patients within the screening programme who were diagnosed with a luminal A‐like primary tumour and/or lymph node metastases. Stage, molecular pathology and mode of detection help to define patients at low risk of death from breast cancer.

Low‐risk group identified

Risk of basal cell carcinoma in Swedish organ transplant recipients: a population-based study

BACKGROUND

Risk of basal cell carcinoma (BCC) has been reported to be several-fold increased among organ transplant recipients (OTRs). However, due to lack of reliable BCC registration, population-based risk estimates are scarce.

OBJECTIVES

To characterize risk of BCC among OTRs compared with the general population, and contrast with risk of cutaneous squamous cell carcinoma (SCC).

SUBJECTS AND METHODS

OTRs transplanted during 2004-2011 were identified through national healthcare registers and linked with the nationwide Swedish BCC Register initialized in 2004. Relative risk of BCC was expressed as standardized incidence ratios (SIR) with 95% confidence intervals (CI).

RESULTS

Altogether, 4023 transplanted patients developed 341 BCCs during follow-up. Compared with the general population, the relative risk of BCC was increased sixfold (SIR 6·1, 95% CI 5·4-6·9). The risk was higher in kidney and heart/lung than in liver recipients (SIRkidney 7·2, 6·3-8·3; SIRheart/lung 5·8, 4·0-8·2; SIRliver 2·6, 1·7-4·0), and risk increased with time since transplantation (Ptrend < 0·01). The SCC to BCC ratio was 1 : 1·7 and BCC developed earlier after transplantation than SCC. Distribution of anatomical sites and histological types did not differ substantially between OTR- and population-BCCs.

CONCLUSIONS

Risk of BCC was strikingly elevated in OTRs compared with the general population. Risk was higher in kidney recipients and increased with follow-up time. These findings support a tumour-promoting effect of immunosuppressive drugs in BCC development. The low SCC to BCC ratio was possibly attributed to short follow-up time.

Parallel mechanisms of polypyrrole self-discharge in aqueous media

Self-discharge of oxidized polypyrrole is composed of two parallel self-discharge mechanisms and their relative contributions depend on pH and potential.

The clinical significance of BRAF and NRAS mutations in a clinic-based metastatic melanoma cohort

BACKGROUND

BRAF and NRAS mutations are frequently found in melanoma tumours, and recently developed BRAF-targeted therapies demonstrate significant clinical benefit.

OBJECTIVES

We sought to investigate the clinical significance of BRAF and NRAS mutations in a clinic-based metastatic melanoma cohort.

METHODS

In total, 237 tumours, mostly metastatic lesions, from 203 patients were screened for mutations in exon 15 of BRAF and exon 2 of NRAS using Sanger sequencing. BRAF and NRAS mutation status was analysed in relation to clinical and histopathological characteristics, and outcome.

RESULTS

Mutation in BRAF and NRAS was present in 43% (88% V600E, 10% V600K) and 30% (48% Q61K, 40% Q61R) of metastatic melanomas, respectively. We found consistent BRAF and NRAS mutation status in all but one of 27 patients with multiple metastases. BRAF mutation was associated with younger age at primary diagnosis (P = 0.02). Among patients with distant metastatic melanoma, patients with BRAF-mutant tumours without BRAF inhibitor treatment had inferior survival compared with patients with BRAF inhibitor treatment [hazard ratio (HR) 2.35, 95% confidence interval (CI) 1.10-5.01, P = 0.03]. We also observed a trend towards better prognosis for patients with wild-type and NRAS-mutant tumours compared with BRAF V600E-mutant tumours (HR 0.64, 95% CI 0.39-1.04, P = 0.07; and HR 0.76, 95% CI 0.48-1.21, P = 0.25, respectively).

CONCLUSIONS

We were able to confirm the effect of BRAF inhibitor treatment in a single clinical institution. The results suggest further that BRAF mutation is a weak prognostic factor but a strong predictive factor and that BRAF-mutant melanoma might constitute one or more distinct subtypes of the disease with certain aetiology and clinical outcome.

Avoidance of sun exposure is a risk factor for all-cause mortality: results from the Melanoma in Southern Sweden cohort

BACKGROUND

Sunlight exposure and fair skin are major determinants of human vitamin D production, but they are also risk factors for cutaneous malignant melanoma (MM). There is epidemiological evidence that all-cause mortality is related to low vitamin D levels.

METHODS

We assessed the avoidance of sun exposure as a risk factor for all-cause mortality for 29 518 Swedish women in a prospective 20-year follow-up of the Melanoma in Southern Sweden (MISS) cohort. Women were recruited from 1990 to 1992 and were aged 25 to 64 years at the start of the study. We obtained detailed information at baseline on their sun exposure habits and potential confounders. Multivariable flexible parametric survival analysis was applied to the data.

RESULTS

There were 2545 deaths amongst the 29 518 women who responded to the initial questionnaire. We found that all-cause mortality was inversely related to sun exposure habits. The mortality rate amongst avoiders of sun exposure was approximately twofold higher compared with the highest sun exposure group, resulting in excess mortality with a population attributable risk of 3%.

CONCLUSION

The results of this study provide observational evidence that avoiding sun exposure is a risk factor for all-cause mortality. Following sun exposure advice that is very restrictive in countries with low solar intensity might in fact be harmful to women's health.

Abstract P6-06-52: Increased expression of insulin-like growth factor-1 receptor is associated with better prognosis in a cohort of tamoxifen treated women

Background: Treatment resistance is a well-known problem in estrogen receptor (ER) positive breast cancer. Complementary therapies are investigated for women who do not respond or who develop resistance against standard ER targeted treatment. Insulin-like growth factor-1 receptor (IGF1R) and its signaling pathway has been suggested to cause estrogen-independent cell growth and survival. Therapy against targets within the pathway is currently investigated in clinical trials. The aim of this study was to investigate if the IGF1R/mTOR pathway was activated or deregulated in breast cancer patients and to explore if any of the markers were prognostic, with or without adjuvant tamoxifen.

Material and methods: Two patient cohorts were investigated by immunohistochemistry using tissue microarrays. The first cohort (N = 264) consisted of mainly post-menopausal women with stage II breast cancer treated with tamoxifen for 2 years irrespective of ER status. The second cohort (N = 206) consisted of mainly medically untreated, pre-menopausal patients with node-negative breast cancer. The protein expression of IGF1R, p-mTOR and p-S6rp were investigated. Cytoplasmic staining was evaluated for all markers and membrane staining was additionally evaluated for IGF1R. Statistical analyses were based on the intensity (0-3) of staining. Expression of IGF1R gave similar results in the cytoplasm and membrane, and p-values for cytoplasmic staining are reported below. Distant disease free survival (DDFS) at 5 years was used as end-point.

Results: IGF1R expression was positively associated with ERa (p&lt;0.001 in Mann-Whitney ranksum test), PgR (p&lt;0.001) and HER2 (p = 0.042) expression in cohort 1, and also with Ki67 (p = 0.006) in cohort 2. p-S6rp was positively associated with ERα in cohort 1 (p&lt;0.001) and HER2 (p = 0.004) in cohort 2. p-mTOR was positively associated only with Ki67 (p&lt;0.001) in cohort 1. High expression of IGF1R was associated with a significantly better prognosis in cohort 1 (HR = 0.7 per intensity step, 95% CI = 0.5-0.9, p = 0.016 using Cox regression). When stratifying for ER status the effect was found in ER negative (ER-) (N = 80, HR = 0.6, 95% CI = 0.4-1.0, p = 0.03) but not in ER positive (ER+) patients (N = 174, HR 1.2, 95% CI = 0.8-2.0, p = 0.40). Both the effect in the ER- subgroup as well as the difference between ER- and ER+ patients were confirmed in interaction analysis and remains after adjustment for age, tumor size, node status, HER2, Ki67, and menopausal status (p = 0.06 for interaction). In cohort 2, no relation to DDFS could be found for IGF1R. p-mTOR and p-S6rp showed no relationship to prognosis in either of the cohorts.

Conclusion: We found that high IGF1R expression was associated with a better prognosis for tamoxifen treated women. This effect could be seen in the ER- but not in the ER+ subgroup of patients. The lack of co-activation of downstream markers (p-mTOR and p-S6rp) in the IGF1R pathway shows that the prognostic effect is not due to complete activation of this pathway.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-06-52.

Abstract P2-18-10: High risk of late in-breast tumour recurrence after BRCA1/2-associated breast cancer

Background: In the general population, partial mastectomy followed by postoperative radiotherapy (PMRT) reduces the risk of local recurrences of breast cancers to a level comparable to the risk after mastectomy (M). However, for BRCA1/2 mutation carriers, a potentially increased risk of a new primary breast cancer in the ipsilateral breast must be taken into account when recommendations about type of surgery are given. To address this question, we conducted a retrospective study on the risk of in-breast tumor recurrence (IBTR) after PMRT in BRCA1/2 mutation carriers.

Methods: Women with invasive breast cancer from families with a pathogenic mutation in BRCA1 or BRCA2 identified at a single institution were included in the study (n = 174). Median age at diagnosis was 43 years and median follow-up was 10.8 years for patients alive at end of follow-up. Patients who were treated with PMRT (n = 45) were compared with patients who had M as primary surgery (n = 118). Endpoints were local recurrence as first failure (LR [IBTR or thoracic wall recurrence]), overall survival (OS), breast cancer-specific survuval (BCSS) and distant disease-free survival (DDFS). LR, OS, BCSS and DDFS were estimated using the Kaplan-Meier method and compared by the log-rank test. For calculation of hazard ratios and for multivariable analysis, the Cox proportional hazards model was used.

Results: In univariate analysis, no difference in OS, BCSS or DDFS was seen between the PMRT and M groups (HR 0.9 [95% CI 0.5-1.4], HR 0.9 [CI 0.5-1.7] and HR 0.8 [CI 0.5-1.5], respectively). In multivariable analysis, adjusting for tumor stage, age and use of adjuvant chemotherapy, the hazard ratios were lower (HR 0.8 [95% CI 0.4-1.3], HR 0.6 [CI 0.3-1.3] and HR 0.6 [CI 0.3-1.1], respectively), but remained inconclusive.

Compared to M, PMRT was associated with an increased risk for LR in univariate analysis (HR 4.0 [CI 1.6-9.8]). In the M group, all local recurrences were seen in the first 5 years. As opposed to this, in the PMRT group the rate of IBTR was rather constant over 15 years of follow-up. The cumulative risk for IBTR in the PMRT group was 19%, 32% and 43% after 5, 10 and 15 years, respectively.

Conclusion: BRCA1/2 mutation carriers treated with PMRT have a high risk for IBTR, many of which are new primary breast cancers. This must be thoroughly discussed with the patient and is an example of how rapid treatment-focused genetic testing already could influence choice of treatment.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-18-10.

Drug survival on TNF inhibitors in patients with rheumatoid arthritis comparison of adalimumab, etanercept and infliximab

Objective

To compare drug survival on adalimumab, etanercept and infliximab in patients with rheumatoid arthritis (RA).

Methods

Patients with RA (n=9139; 76% women; mean age 56 years) starting their first tumour necrosis factor (TNF) inhibitor between 2003 and 2011 were identified in the Swedish Biologics Register (ARTIS). Data were collected through 31 December 2011. Drug survival over up to 5 years of follow-up was compared overall and by period of treatment start (2003–2005/2006–2009; n=3168/4184) with adjustment for age, sex, education, period, health assessment questionnaire (HAQ), disease duration, concomitant disease modifying antirheumatic drug (DMARD) treatment and general frailty (using hospitalisation history as proxy).

Results

During 20 198 person-years (mean/median 2.2/1.7 years) of follow-up, 3782 patients discontinued their first biological (19/100 person-years; 51% due to inefficacy, 36% due to adverse events). Compared with etanercept, infliximab (adjusted HR 1.63, 95% CI 1.51 to 1.77) and adalimumab initiators had higher discontinuation rates (1.26, 95% CI 1.16 to 1.37), and infliximab had a higher discontinuation rate than adalimumab (1.28, 95% CI 1.18 to 1.40). These findings were consistent across periods, but were modified by time for adalimumab versus etanercept (p<0.001; between-drug difference highest the 1st year in both periods). The discontinuation rate was higher for starters in 2006–2009 than 2003–2005 (adjusted HR 1.12, 95% CI 1.04 to 1.20). The composition of 1-year discontinuations also changed from 2003–2005 vs 2006–2009: adverse events decreased from 45% to 35%, while inefficacy increased from 43% to 53% (p<0.001).

Conclusions

Discontinuation rates were higher for infliximab compared with adalimumab and etanercept initiators, and for adalimumab versus etanercept during the 1st year. Discontinuation rates increased with calendar period, as did the percentage discontinuations due to inefficacy.

Population-based data from the Swedish Colon Cancer Registry

BACKGROUND

Evaluating the external validity of clinical trials requires knowledge not only of the study population but also of a relevant reference population. The main aim of this study was to present data from a large, contemporary, population-based cohort of patients with colonic cancer.

METHODS

Data on patients diagnosed between 2007 and 2011 were extracted from the Swedish Colon Cancer Registry. The data, registered prospectively in a national population of almost 10 million, included over 99 per cent of all diagnosed adenocarcinomas of the colon.

RESULTS

This analysis included 18,889 patients with 19,526 tumours (3·0 per cent had synchronous tumours). The sex distribution was fairly equal, and the median age was 74·1 (interquartile range 65-81) years. The overall and relative (cancer-specific) survival rates after 3 years were 62·7 and 71·4 per cent respectively. Some 88·0 per cent of the patients were operated on, and 83·8 per cent had tumours resected. Median blood loss during bowel resection was 200 (mean 311) ml, and the median operating time was 160 min; 5·6 per cent of the procedures were laparoscopic. Preoperative chemotherapy was administered to 2·1 per cent of patients; postoperative chemotherapy was planned in 90·1 per cent of fit patients aged less than 75 years with stage III disease. In patients operated on in an emergency setting (21·5 per cent), the preoperative evaluation was less extensive, the proportion of R0 resections was lower, and the outcomes were poorer, in both the short and long term.

CONCLUSION

These population-based data represent good-quality reference points.

Abstract P2-10-37: Long-term prognosis of early breast cancer in a population-based cohort with a known BRCA1/2 mutation status

Background: The impact of germline BRCA1/2 mutations on breast cancer prognosis and treatment is currently not clear. We investigate how different factors, including BRCA1/2 mutation status, correlate with long-term outcome in early breast cancer in a population-based cohort.

Methods: As previously reported, all women in the Southern Health Care Region in Sweden with breast cancer diagnosed before age 41 years between 1990 and 1995 (n = 262) were contacted in 1996 and offered mutation analysis of the BRCA1 and BRCA2 genes. Mutation analysis was performed on 234 of them, the others were excluded from further studies. 23 pathogenic mutations were found; 18 in BRCA1 and 5 in BRCA2. We will now present data on tumor and patient characteristics, treatment and long-term follow-up for the patients from this population-based cohort. Three patients have declined further study follow-up and were therefore excluded. Six patients had metastatic breast cancer at the time diagnosis (one of them a BRCA2 mutation carrier) and are also excluded, leaving 225 in the present analysis.

Results: Among the 225 cases estrogen receptor (ER) status is known for 191 (49% ER+, 51% ER−); histologic grade for 169 (24% grade I; 33% grade II; 43% grade III); stage for 225 (36% stage I, 44% stage II, 20% stage III); type of surgery, adjuvant systemic treatment and postoperative radiotherapy for 225. In the cohort, 46% received adjuvant or neoadjuvant chemotherapy, whereas 15% were given adjuvant endocrine therapy. There is complete follow-up &gt; 10 years for 205 and present vital status for 224.

Of the 225 women, 128 (57%) have had a local, regional or distant recurrence of breast cancer (contralateral breast cancer not included) at the date of last follow-up. One hundred and six patients (47%) have died, 98 of whom from breast cancer and 2 from presumably radiation-induced malignancies caused by postoperative radiotherapy. Thirteen of the 22 BRCA1/2 mutation carriers (59 %) have died, all from breast cancer. Of the 9 mutation carriers that are alive today, 3 have had an in-breast tumor recurrence and 3 have had a contralateral breast cancer; the 3 women that have had neither have all performed bilateral prophylactic mastectomy as well as prophylactic salpingo-ooforectomy.

Data on how the long-term prognosis of early breast cancer is correlated to BRCA1/2 mutation status, adjuvant treatment, stage at diagnosis, histologic grade and ER status of the tumor will be presented.

Conclusion: Women with early breast cancer in this cohort from the early 90ies had a poor long-term prognosis. The prognosis for women diagnosed with early breast cancer today is likely to be better, thanks to more modern chemotherapy regimens, endocrine and targeted treatments. The prognostic significance of BRCA1/2 mutation status will be further analyzed.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-10-37.

Abstract P2-10-36: Analysis of biomarker expression and biological subtype in primary tumour, corresponding lymph node and distant metastasis with 5-year follow-up

Background: Biological variation in genotype and phenotype of primary breast cancer explains the heterogeneity of the disease and subsequent outcome. Choice of treatment is routinely based on the biomarker expression of the primary tumour with regard to estrogen- (ER) and progesterone (PR) receptor status, human epidermal growth factor receptor 2 (HER2) status and the proliferation marker Ki67, individually. Recently, gene expression profiling and subsequent immunohistochemical studies have identified biologically distinct subtypes by using a combination of biomarkers which have been shown to be of prognostic value beyond the previous known. However, tumour progression theories propose a change in biomarker expression during development from primary tumour to distant metastasis with implications on choice of therapy. The aim of this study was to compare biomarker expression individually and according to biological subtype between tumour samples from primary tumour, lymph node metastasis and distant metastasis from the same patient.

Material and methods: From an original cohort of 569 patients with primary breast cancer, tissue microarrays were constructed from archival tissue blocks of primary tumour (n = 521), paired lymph node metastasis (n = 147) and biopsies from distant metastasis (n = 42). The samples were evaluated by two independent pathologists. The individual biomarker expression as well as subtype classification (Luminal A: ER+ and/or PR+, Ki67≤ 20% and HER2−. Luminal B: ER+ and/or PR+, Ki67&gt; 20% and/or HER2+. HER2 type: ER/PR−, HER2+. Basal-like: ER/PR−, HER2−, CK5/6+ and/or EGFR+) were compared between primary tumour, lymph node metastasis and distant metastasis. Survival outcome were estimated using the Kaplan-Meier method and log rank test. The primary end-point was distant disease-free survival (DDFS).

Results: Distribution according to subtype.