Glucocorticoids are differentially synthesized along the murine and human respiratory tree.

BACKGROUND: Synthetic glucocorticoids (GC) are effective in the treatment of inflammatory diseases of the lung. However, long-term use leads to severe side effects. Endogenous GC can be synthesized locally, either de novo from cholesterol in a 11ß-hydroxylase (Cyp11b1)-dependent manner, or by reactivation from 11-dehydrocorticosterone/cortisone by 11ß-hydroxysteroid dehydrogenase 1 (Hsd11b1). We aimed to define the molecular pathways of endogenous GC synthesis along the respiratory tree to provide a basis for understanding how local GC synthesis contributes to tissue homeostasis. METHODS: Expression of steroidogenic enzymes in murine lung epithelium was analyzed by macroscopic and laser capture microdissection, followed by RT-qPCR. Flow cytometry analysis was performed to identify the cellular source of steroidogenic enzymes. Additionally, the induction of steroidogenic enzyme expression in the lung was analyzed after lipopolysaccharide (LPS) injection. mRNA and protein expression of steroidogenic enzymes was confirmed in human lung tissue by RT-qPCR and immunohistochemistry. Furthermore, GC synthesis was examined in ex vivo cultures of fresh tissue from mice and human lobectomy patients. RESULTS: We observed that the murine and human lung tissue differentially expresses synthesis pathway-determining enzymes along the respiratory tree. We detected Hsd11b1 expression in bronchial, alveolar, club and basal epithelial cells, whereas Cyp11b1 expression was detectable only in tracheal epithelial cells of mice. Accordingly, de novo synthesis of bioactive GC occurred in the large conducting airways, whereas reactivation occurred everywhere along the respiratory tree. Strikingly, Cyp11b1 but not Hsd11b1 expression was enhanced in the trachea upon LPS injection in mice. CONCLUSION: We report here the differential synthesis of bioactive GC along the murine and human respiratory tree. Thus, extra-adrenal de novo GC synthesis and reactivation may differentially contribute to the regulation of immunological and inflammatory processes in the lung.

Discrepancies of asbestos body and fiber content between formalin-fixed and corresponding paraffin embedded lung tissue.

BACKGROUND: Formalin-fixed lung tissue and paraffin blocks containing peripheral lung tissue obtained from subjects with an occupational asbestos exposure are both regarded to be suitable to determine asbestos load. Because sample preparation of paraffin blocks requires a more intense treatment than formalin-fixed tissue, we tested whether asbestos analysis of formalin-fixed lung tissue and paraffin blocks obtained from the same patients deliver comparable results. MATERIALS AND METHODS: We determined numbers of asbestos bodies (AB) and amphibole asbestos fibers (AF) in formalin-fixed lung tissue and corresponding paraffin blocks from 36 patients. For AB counts, samples were digested in sodium hypochlorite. For AF analysis, tissue was freeze-dried and then ashed. Results were reported as numbers of AB and AF per gram dry lung tissue. RESULTS: Both AB counts as well as AF counts were lower in paraffin blocks than formalin-fixed lung tissue. Compared to formalin-fixed tissue, the limit of detection was higher for paraffin blocks, rendering more results from paraffin blocks not interpretable than from formalin-fixed tissue (8 samples versus 1 for AB and 15 samples versus 4 for AF). DISCUSSION AND CONCLUSION: Asbestos analysis of paraffin blocks may lead to underestimation of asbestos exposure. This should be considered when assessing occupational asbestos exposure through lung dust analysis in medico-legal evaluation.

Visualisation of interstitial lung disease by molecular imaging of integrin αvß3 and somatostatin receptor 2.

OBJECTIVE: To evaluate integrin αvß3 (alpha-v-beta-3)-targeted and somatostatin receptor 2 (SSTR2)-targeted nuclear imaging for the visualisation of interstitial lung disease (ILD). METHODS: The pulmonary expression of integrin αvß3 and SSTR2 was analysed in patients with different forms of ILD as well as in bleomycin (BLM)-treated mice and respective controls using immunohistochemistry. Single photon emission CT/CT (SPECT/CT) was performed on days 3, 7 and 14 after BLM instillation using the integrin αvß3-targeting 177Lu-DOTA-RGD and the SSTR2-targeting 177Lu-DOTA-NOC radiotracer. The specific pulmonary accumulation of the radiotracers over time was assessed by in vivo and ex vivo SPECT/CT scans and by biodistribution studies. RESULTS: Expression of integrin αvß3 and SSTR2 was substantially increased in human ILD regardless of the subtype. Similarly, in lungs of BLM-challenged mice, but not of controls, both imaging targets were stage-specifically overexpressed. While integrin αvß3 was most abundantly upregulated on day 7, the inflammatory stage of BLM-induced lung fibrosis, SSTR2 expression peaked on day 14, the established fibrotic stage. In agreement with the findings on tissue level, targeted nuclear imaging using SPECT/CT specifically detected both imaging targets ex vivo and in vivo, and thus visualised different stages of experimental ILD. CONCLUSION: Our preclinical proof-of-concept study suggests that specific visualisation of molecular processes in ILD by targeted nuclear imaging is feasible. If transferred into clinics, where imaging is considered an integral part of patients' management, the additional information derived from specific imaging tools could represent a first step towards precision medicine in ILD.

Nuclear grade and necrosis predict prognosis in malignant epithelioid pleural mesothelioma: a multi-institutional study.

A recently described nuclear grading system predicted survival in patients with epithelioid malignant pleural mesothelioma. The current study was undertaken to validate the grading system and to identify additional prognostic factors. We analyzed cases of epithelioid malignant pleural mesothelioma from 17 institutions across the globe from 1998 to 2014. Nuclear grade was computed combining nuclear atypia and mitotic count into a grade of I-III using the published system. Nuclear grade was assessed by one pathologist for three institutions, the remaining were scored independently. The presence or absence of necrosis and predominant growth pattern were also evaluated. Two additional scoring systems were evaluated, one combining nuclear grade and necrosis and the other mitotic count and necrosis. Median overall survival was the primary endpoint. A total of 776 cases were identified including 301 (39%) nuclear grade I tumors, 354 (45%) grade II tumors and 121 (16%) grade III tumors. The overall survival was 16 months, and correlated independently with age (P=0.006), sex (0.015), necrosis (0.030), mitotic count (0.001), nuclear atypia (0.009), nuclear grade (<0.0001), and mitosis and necrosis score (<0.0001). The addition of necrosis to nuclear grade further stratified overall survival, allowing classification of epithelioid malignant pleural mesothelioma into four distinct prognostic groups: nuclear grade I tumors without necrosis (29 months), nuclear grade I tumors with necrosis and grade II tumors without necrosis (16 months), nuclear grade II tumors with necrosis (10 months) and nuclear grade III tumors (8 months). The mitosis-necrosis score stratified patients by survival, but not as well as the combination of necrosis and nuclear grade. This study confirms that nuclear grade predicts survival in epithelioid malignant pleural mesothelioma, identifies necrosis as factor that further stratifies overall survival, and validates the grading system across multiple institutions and among both biopsy and resection specimens. An alternative scoring system, the mitosis-necrosis score is also proposed.

Heterogeneity in Malignant Pleural Mesothelioma.

Despite advances in malignant pleural mesothelioma therapy, life expectancy of affected patients remains short. The limited efficiency of treatment options is mainly caused by inter- and intra-tumor heterogeneity of mesotheliomas. This diversity can be observed at the morphological and molecular levels. Molecular analyses reveal a high heterogeneity (i) between patients; (ii) within different areas of a given tumor in terms of different clonal compositions; and (iii) during treatment over time. The aim of the present review is to highlight this diversity and its therapeutic implications.

Sarcoidosis as a rare cause for symmetrical giant bullous disease.

BACKGROUND: Sarcoidosis presents with typical clinic-radiological findings and shows histologically non-caseating granulomas. Pulmonary manifestations of sarcoidosis can be diverse, involving the intrathoracic lymph nodes and pulmonary parenchyma. CASE PRESENTATION: We here describe a case of a 35-year-old patient who presented with a history of exertion dyspnoea and coughing for the past 20 years. At the age of 15, she was exposed to smoke emanating from a fire. Later, she had exposure to mold for two years, and during her childhood, she had animals such as a cockatiel, dog, cat, gecko, and turtle. Computed tomography of the chest revealed symmetrical apical giant bullous lesions. Histology of the resected bullae showed prominent peribronchial fibrosis with non-necrotizing, non-caseating granulomas and collaps of pulmonary lobules adjacent to the bulla. The absence of granulomatous infection and a markedly elevated CD4:CD8 ratio in bronchoalveolar lavage analysis suggested that the underlying process was sarcoidosis. CONCLUSION: In very rare cases, sarcoidosis can be associated with bilateral symmetrical apical giant bullous disease due to fibrotic and granulomatous changes resulting in a restriction of lung tissue.

GAS5 long non-coding RNA in malignant pleural mesothelioma.

BACKGROUND: Malignant pleural mesothelioma (MPM) is an aggressive cancer with short overall survival. Long non-coding RNAs (lncRNA) are a class of RNAs more than 200 nucleotides long that do not code for protein and are part of the 90% of the human genome that is transcribed. Earlier experimental studies in mice showed GAS5 (growth arrest specific transcript 5) gene deletion in asbestos driven mesothelioma. GAS5 encodes for a lncRNA whose function is not well known, but it has been shown to act as glucocorticoid receptor decoy and microRNA "sponge". Our aim was to investigate the possible role of the GAS5 in the growth of MPM. METHODS: Primary MPM cultures grown in serum-free condition in 3% oxygen or MPM cell lines grown in serum-containing medium were used to investigate the modulation of GAS5 by growth arrest after inhibition of Hedgehog or PI3K/mTOR signalling. Cell cycle length was determined by EdU incorporation assay in doxycycline inducible short hairpinGAS5 clones generated from ZL55SPT cells. Gene expression was quantified by quantitative PCR. To investigate the GAS5 promoter, a 0.77 kb sequence was inserted into a pGL3 reporter vector and luciferase activity was determined after transfection into MPM cells. Localization of GAS5 lncRNA was identified by in situ hybridization. To characterize cells expressing GAS5, expression of podoplanin and Ki-67 was assessed by immunohistochemistry. RESULTS: GAS5 expression was lower in MPM cell lines compared to normal mesothelial cells. GAS5 was upregulated upon growth arrest induced by inhibition of Hedgehog and PI3K/mTOR signalling in in vitro MPM models. The increase in GAS5 lncRNA was accompanied by increased promoter activity. Silencing of GAS5 increased the expression of glucocorticoid responsive genes glucocorticoid inducible leucine-zipper and serum/glucocorticoid-regulated kinase-1 and shortened the length of the cell cycle. Drug induced growth arrest was associated with GAS5 accumulation in the nuclei. GAS5 was abundant in tumoral quiescent cells and it was correlated to podoplanin expression. CONCLUSIONS: The observations that GAS5 levels modify cell proliferation in vitro, and that GAS5 expression in MPM tissue is associated with cell quiescence and podoplanin expression support a role of GAS5 in MPM biology.

Inflammatory cytokines in pulmonary hypertension.

Pulmonary hypertension is an "umbrella term" used for a spectrum of entities resulting in an elevation of the pulmonary arterial pressure. Clinical symptoms include dyspnea and fatigue which in the absence of adequate therapeutic intervention may lead to progressive right heart failure and death. The pathogenesis of pulmonary hypertension is characterized by three major processes including vasoconstriction, vascular remodeling and microthrombotic events. In addition accumulating evidence point to a cytokine driven inflammatory process as a major contributor to the development of pulmonary hypertension.This review summarizes the latest clinical and experimental developments in inflammation associated with pulmonary hypertension with special focus on Interleukin-6, and its role in vascular remodeling in pulmonary hypertension.

Integrated ¹8F-FDG PET/perfusion CT for the monitoring of neoadjuvant chemoradiotherapy in rectal carcinoma: correlation with histopathology.

PURPOSE: The aim of this study was to prospectively monitor changes in the flow-metabolic phenotype (ΔFMP) of rectal carcinoma (RC) after neoadjuvant chemoradiotherapy (CRT) and to evaluate whether ΔFMP of RC correlate with histopathological prognostic factors including response to CRT. METHODS: Sixteen patients with RC (12 men, mean age 60.7 ± 12.8 years) underwent integrated (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/perfusion CT (PET/PCT), followed by neoadjuvant CRT and surgery. In 13 patients, PET/PCT was repeated after CRT. Perfusion [blood flow (BF), blood volume (BV), mean transit time (MTT)] and metabolic [maximum and mean standardized uptake values (SUVmax, SUVmean)] parameters as well as the FMP (BF × SUVmax) were determined before and after CRT by two independent readers and correlated to histopathological prognostic factors of RC (microvessel density, necrosis index, regression index, vascular invasion) derived from resected specimens. The diagnostic performance of ΔFMP for prediction of treatment response was determined. RESULTS: FMP significantly decreased after CRT (p < 0.001), exploiting higher changes after CRT as compared to changes of perfusion and metabolic parameters alone. Before CRT, no significant correlations were found between integrated PET/PCT and any of the histopathological parameters (all p > 0.05). After CRT, BV and SUVmax correlated positively with the necrosis index (r = 0.67/0.70), SUVmax with the invasion of blood vessels (r = 0.62) and ΔFMP with the regression index (r = 0.88; all p < 0.05). ΔFMP showed high accuracy for prediction of histopathological response to CRT (AUC 0.955, 95 % confidence interval 0.833-1.000, p < 0.01) using a cut-off value of -75%. CONCLUSION: In RC, ΔFMP derived from integrated (18)F-FDG PET/PCT is useful for monitoring the effects of neoadjuvant CRT and allows prediction of histopathological response to CRT.

Utility of BAP1, p16, and Methylthio-Adenosine Phosphorylase Immunohistochemistry in Cytological and Histological Samples of Pleural Mesotheliomas.

INTRODUCTION: In most cases, the diagnostic workup of pleural mesotheliomas (MPMs) starts with cytological examination of pleural effusion, but histology is needed to confirm the diagnosis. The introduction of BAP1 and methylthio-adenosine phosphorylase (MTAP) immunohistochemistry has become a powerful tool to confirm the malignant nature of mesothelial proliferations also in cytological specimens. The objective of this study was to determine the concordance of BAP1, MTAP, and p16 expression between cytological and histological samples of patients with MPM. METHODS: Immunohistochemistry of BAP1, MTAP, and p16 was performed on cytological samples and compared with the corresponding histological specimen of 25 patients with MPM. Inflammatory and stromal cells served as positive internal control for all three markers. In addition, samples of 11 patients with reactive mesothelial proliferations served as an external control group. RESULTS: Loss of BAP1, MTAP, and p16 expression was found in 68%, 72%, and 92% of MPM, respectively. Loss of MTAP was associated with loss of p16 expression in all cases. Concordance of BAP1 between cytological and corresponding histological samples was 100% (kappa coefficient 1; p = 0.008). For MTAP and p16, kappa coefficient was 0.9 (p = 0.01) and 0.8 (p = 0.7788), respectively. CONCLUSIONS: Concordant BAP1, MTAP, and p16 expression is found between cytological and corresponding histological samples, indicating that a reliable diagnosis of MPM can be made on cytology only. Of the three markers, BAP1 and MTAP are most reliable in distinguishing malignant from reactive mesothelial proliferations.

Deletions of CDKN2A and MTAP Detected by Copy-Number Variation Array Are Associated with Loss of p16 and MTAP Protein in Pleural Mesothelioma.

CDKN2A deletion is a common alteration in pleural mesothelioma (PM) and frequently associated with co-deletion of MTAP. Since the standard detection method for CDKN2A deletion and FISH analysis is relatively expensive, we here investigated the suitability of inexpensive p16 and MTAP IHC by comparing concordance between IHC and OncoScan CNV arrays on samples from 52 PM patients. Concordance was determined using Cohen's kappa statistics. Loss of CDKN2A was associated with co-deletion of MTAP in 71% of cases. CDKN2A-MTAP copy-number normal cases were also IHC positive in 93% of cases for p16 and 100% for MTAP, while homozygous deletion of CDKN2A-MTAP was always associated with negative IHC for both proteins. In cases with heterozygous CDKN2A-MTAP loss, IHC expression of p16 and MTAP was negative in 100% and 71%, respectively. MTAP and p16 IHC showed high sensitivity (MTAP 86.5%, p16 100%) and specificity (MTAP 100%, p16 93.3%) for the detection of any gene loss. Loss of MTAP expression occurred exclusively in conjunction with loss of p16 labeling. Both p16 and MTAP IHC showed high concordance with Oncoscan CNV arrays (kappa = 0.952, p < 0.0001, and kappa = 0.787, p < 0.0001 respectively). We recommend combined MTAP and p16 immunohistochemistry to confirm the diagnosis of PM.

Occupations and geographical distribution of mesothelioma in Switzerland 1989-2018 - record linkage of an asbestos-exposed population with the Swiss National Cohort.

OBJECTIVE: We investigated the possibility of linking the data of the Swiss Laboratory for Particle Analysis (Silag), a valuable but incomplete data source in the field of asbestos-related diseases, to the Swiss National Cohort (SNC). With the resulting comprehensive dataset, we intended to provide a source for further research in the field. We also conducted preliminary analyses of data focusing on occupations and regional distribution of malignant pleural mesothelioma cases. METHODS: Data of asbestos-exposed individuals available from the Silag were anonymously linked with the SNC by means of deterministic record linkage. From this linkage, data on occupation classified according to the international standard classification of occupations (ISCO) as well as the canton of residence in Switzerland could be retrieved. RESULTS: Of 838 eligible individuals from the Silag data, 788 (94.0%) could be linked to the SNC database, including 476 mesothelioma cases. In 340 cases of the latter, data on occupation and industries were available. Although the majority of them were blue-collar workers, a significant proportion (n = 44, 12.9%) had executive professions. The Canton of residence in 1990 was established in 430 of subjects with mesothelioma. A cluster could be identified in eastern Switzerland, especially in the canton of Glarus. CONCLUSIONS: It was possible to link the datasets to a large extent thereby creating a data source for further research. Of note, the linkage provided data on occupation of a selection of mesothelioma cases in Switzerland.

Adrenal myelolipoma: Defining the role of surgery. A case report.

INTRODUCTION AND IMPORTANCE: Adrenal myelolipomas (AMLs) are rare, non-functional, benign tumours mostly diagnosed incidentally. They present as small and unilateral masses that are histologically composed of mature adipose tissue with admixed haemopoietic elements. In a small percentage of patients, pressure symptoms, retroperitoneal haemorrhage or tumour rupture may occur. However, indications for surgery in the majority of asymptomatic patients are poorly defined. CASE PRESENTATION: A 44-year old male patient presented with signs of gastroenteritis. Computed tomography (CT) imaging revealed an encapsulated, sharply delineated mass measuring 87 × 76 × 87 mm displacing the right adrenal gland. Average attenuation was -30 Hounsfield units. Given the pathognomonic features, an AML was suspected. The patient underwent open tumour resection and the diagnosis was histologically confirmed. CLINICAL DISCUSSION: Small (<4 cm), homogeneous, non-hormone secreting incidentalomas with an attenuation of <10 Hounsfield units on non-contrast CT are considered benign requiring neither treatment nor follow-up. Giant AMLs (>10 cm) may cause symptoms or complications and are therefore considered candidates for surgery. The treatment strategy of asymptomatic AMLs ranging from 4 cm to 10 cm, however, is controversial and poorly defined. The role of surgery in this specific subgroup of patients is studied. CONCLUSION: Surgery is indicated in the presence of a tumour diameter above 6 cm, rapid tumour growth (RECIST 1.1 criteria for progressive disease at 6-12 months follow-up), imaging suspicious of malignancy, radiological signs of local invasion, functioning ipsilateral adrenocortical adenoma, pressure-related symptoms and signs of retroperitoneal bleeding or spontaneous tumour rupture.

Transbronchial Cryobiopsy Compared to Forceps Biopsy for Diagnosis of Acute Cellular Rejection in Lung Transplants: Analysis of 63 Consecutive Procedures.

BACKGROUND: Acute cellular rejection (ACR) is a complication after lung transplantation (LTx). The diagnosis of ACR is based on histologic findings using transbronchial forceps biopsy (FB). However, its diagnostic accuracy is limited because of the small biopsy size and crush artifacts. Transbronchial cryobiopsy (CB) provides a larger tissue size compared with FB. METHODS: FB and CB were obtained consecutively during the same bronchoscopy (February 2020-April 2021). All biopsies were scored according to the ISHLT criteria by three pathologists. Interobserver agreement was scored by the kappa index. We assessed the severity of bleeding and the presence of pneumothorax. RESULTS: In total, 35 lung transplant recipients were included, and 126 CBs and 315 FBs were performed in 63 consecutive bronchoscopies. ACR (A1-A3, minimal-moderate) was detected in 18 cases (28.6%) by CB, whereas ACR was detected in 3 cases (4.8%) by FB. Moderate and severe bleeding complicated FB and CB procedures in 23 cases (36.5%) and 1 case (1.6%), respectively. Pneumothorax occurred in 6.3% of patients. The interobserver agreement was comparable for both CB and FB. CONCLUSIONS: CB provided an improved diagnostic yield for ACR diagnosis, leading to reclassification and changes in treatment strategies in 28.6% of cases. Prospective studies should better define the role of CB after LTx.

Heterogeneous RNA editing and influence of ADAR2 on mesothelioma chemoresistance and the tumor microenvironment.

We previously observed increased levels of adenosine-deaminase-acting-on-dsRNA (Adar)-dependent RNA editing during mesothelioma development in mice exposed to asbestos. The aim of this study was to characterize and assess the role of ADAR-dependent RNA editing in mesothelioma. We found that tumors and mesothelioma primary cultures have higher ADAR-mediated RNA editing compared to mesothelial cells. Unsupervised clustering of editing in different genomic regions revealed heterogeneity between tumor samples as well as mesothelioma primary cultures. ADAR2 expression levels are higher in BRCA1-associated protein 1 wild-type tumors, with corresponding changes in RNA editing in transcripts and 3'UTR. ADAR2 knockdown and rescue models indicated a role in cell proliferation, altered cell cycle, increased sensitivity to antifolate treatment, and type-1 interferon signaling upregulation, leading to changes in the microenvironment in vivo. Our data indicate that RNA editing contributes to mesothelioma heterogeneity and highlights an important role of ADAR2 not only in growth regulation in mesothelioma but also in chemotherapy response, in addition to regulating inflammatory response downstream of sensing nucleic acid structures.

Sarcoidosis - a multisystem disease.

Sarcoidosis is a systemic inflammatory disease, characterised by granuloma formation upon an unknown trigger in genetically predisposed individuals. The inflammation is characterised by an activation of both the innate immune system, with macrophages differentiating into epitheloid cells and dendritic cells, and the adaptive immune system, particularly T helper (Th) 1 and Th17 cells. Since all organs can be affected to varying extents, clinical presentation is often diverse. Most commonly, the lungs, lymph nodes, skin and eyes are involved, whereas cardiac, renal and neurological manifestations are less common but associated with higher morbidity. Depending on the clinical symptoms, a detailed evaluation including thorough clinical examination, imaging and laboratory tests should explore all possible organ involvements. In some patients, fatigue manifests as a para-sarcoidosis symptom impacting quality of life, even if sarcoidosis is in remission. Some acute syndromic presentations, such as Löfgren's syndrome, have a good prognosis and are commonly self-limiting. If possible, a topical treatment, for example for cutaneous sarcoidosis or bronchial involvement, should be applied. Treatment of severe cases with persisting disease activity necessitates long-term immunosuppressive drugs, with glucocorticoids as the first-line option. Steroid-sparing and second-line drugs include methotrexate, azathioprine, mycophenolate mofetil and immunomodulators such hydroxychloroquine, with the latter being first-line therapy in cutaneous sarcoidosis. Tumour necrosis factor-alpha inhibitors (particularly adalimumab and infliximab) are used as third-line agents but are administered earlier in cases of persistent disease activity, severe organ-involvement or intolerance to conventional drugs. Treatment decisions should be based on a multidisciplinary approach, depending on organ involvement and treatment tolerability. Para-sarcoidosis manifestations, particularly fatigue, should also be carefully addressed, where the patient could also be enrolled in multidimensional rehabilitation programmes. With various organ involvement and different phenotypes, larger studies including real-world data from registries are necessary to evaluate different sarcoidosis endotypes and preferential treatment pathways.

Alterations in BAP1 Are Associated with Cisplatin Resistance through Inhibition of Apoptosis in Malignant Pleural Mesothelioma.

PURPOSE: The clinical standard treatment for patients with malignant pleural mesothelioma (MPM) includes a cisplatin-based chemotherapy, leading to reduction of tumor size in only a minority of patients. Predicting response to chemotherapy in patients with MPM by using a genetic marker would, therefore, enable patient stratification. EXPERIMENTAL DESIGN: In this retrospective biomarker study, eligible patients had resectable MPM, measurable disease, and available primary MPM tissue. All patients underwent first-line treatment with cisplatin and pemetrexed, followed by surgery. Thorough molecular analysis was performed (whole-exome and targeted deep sequencing, and copy-number analyses), and also mechanistic in vitro data (viability assays, Western blots, and immunoprecipitation) using mesothelioma cell lines with and without siRNA-mediated BRCA1-associated protein 1 (BAP1) knockdown were provided. RESULTS: In a training cohort of patients with MPM (n = 28), mutations or deletions of BAP1 each predicted resistance to chemotherapy in patients with primary MPM. The negative predictive value of BAP1 loss in patients with MPM was confirmed by amplicon sequencing and copy-number array technology in an independent test cohort (n = 39). Preliminary mechanistic studies using siRNA-based knockdown of BAP1 in MPM cell culture models along with immunoprecipitation assays confirmed chemoresistance in vitro, possibly through inhibition of apoptosis and transcriptional regulation of the BAP1/HCF1/E2F1 axis. CONCLUSIONS: Alterations in BAP1 in MPM were a negative predictor for response to chemotherapy and could possibly be used as a companion biomarker for treatment decision.

Small cell carcinoma of the lung and large cell neuroendocrine carcinoma interobserver variability.

AIMS: To test the hypothesis that the published morphological criteria permit reliable segregation of small cell carcinoma of the lung (SCLC) and large cell neuroendocrine carcinoma (LCNEC) cases by determining the interobserver variation. METHODS AND RESULTS: One hundred and seventy cases of SCLC, LCNEC and cases diagnosed as neuroendocrine lung carcinoma before LCNEC had been established as a diagnostic category were retrieved from the archives of the assessor's institutes. A representative haematoxylin and eosin section from each case was selected for review. Batches of cases were circulated among nine pathologists with a special interest in pulmonary pathology. Participants were asked to classify the cases histologically according to the 2004 World Health Organization (WHO) criteria. The diagnoses were collected and kappa values calculated. Unanimity of diagnosis was achieved for only 20 cases; a majority diagnosis was reached for 115 cases. In 35 cases no consensus diagnosis could be reached. There was striking variability amongst assessors in diagnosing SCLC and LCNEC. The overall level of agreement for all cases included in this study was fair (kappa=0.40). CONCLUSIONS: Using non-preselected cases, the morphological WHO criteria for diagnosing SCLC and LCNEC leave room for subjective pathological interpretation, which results in imprecise categorization of SCLC and LCNEC cases.