TYPE: Abstract TOPIC: Disorders of the Pleura PURPOSE: Malignant pleural mesothelioma (MPM) is an asbestos-related fatal cancer. Since MPM is commonly diagnosed in advanced stages, the identification of specific biomarkers of early diagnosis in high-risk subjects, is of paramount importance. In previous studies were identified dysregulated circulating miRNAs in sera from MPM patients, workers ex-exposed to asbestos fibers (WEA) and healthy subjects (HS). METHODS: The expression level of circulating miR-197-3p was quantified in larger quantity (n=236) of serum samples from three cohorts: MPM (n=99), WEA (n= 75) and healthy subjects (HS, n=62) using both Real-Time qPCR (RT-qPCR) and droplet digital PCR (ddPCR) techniques. Clinicopathological characteristics, occupational, non-occupational information and survival were analyzed. Intracellular miRNAs were analyzed by ddPCR in MPM cell lines and normal mesothelial cells. RESULTS: In MPM cohort, a mean of 549.0 and 901.2 copies/μl of miR-197-3p cDNA were detected by RT-qPCR and ddPCR. Interestingly, the expression level of mir-197-3p in sera from MPM patients tested higher compared to WEA group (p = 0.0034**) and lower compared to HS (p = 0.039*). Our data confirm that overall survival (OS) was significantly influenced by histological subtype and pleurectomy. Increased levels of miR-197-3p were detected on MPM cell lines compared to normal mesothelial cells (p<0.0001****). CONCLUSIONS: Our study indicates that miR-197-3p is significantly dysregulated in sera and cells from MPM affected patients. It is significantly up-regulated compared to WEA and down-regulated compared to HS. CLINICAL IMPLICATIONS: Dysregulated miR-197-3p is proposed as a new potential biomarker of MPM, which onset occurs in most cases, in high-risk WEA subjects. DISCLOSURE: Nothing to declare. KEYWORD: asbestos; worker; serum; microRNA; biomarker; mesothelioma

Introduction: Malignant pleural mesothelioma (MPM) is an aggressive tumor strongly associated with asbestos exposure. Patients are usually diagnosed when current treatments have limited benefits, highlighting the need for noninvasive early diagnostic tests to monitor asbestos-exposed people. Methods: We used a genome-wide methylation array to identify, in asbestos-exposed subjects, novel blood DNA methylation markers of MPM in 163 MPM cases and 137 cancer-free controls (82 MPM cases and 68 controls, training set; replication in 81 MPM cases and 69 controls, test set) sampled from the same areas. Results: Evidence of differential methylation between MPM cases and controls was found (more than 800 cytosineguanine dinucleotide sites, false discovery rate p value (p(fdr)) < 0.05), mainly in immune system-related genes. Considering the top differentially methylated signals, seven single-cytosine-guanine dinucleotides and five genomic regions of coordinated methylation replicated with similar effect size in the test set (p(fdr) < 0.05). The top hypomethylated single-CpG (cases versus controls effect size less than -0.15, p(fdr) < 0.05 in both the training and test sets) was detected in FOXK1 (Forkhead-box K1) gene, an interactor of BAP1 which was found mutated in MPM tissue and as germline mutation in familial MPM. In the test set, comparison of receiver operating characteristic curves and the area under the curve (AUC) of two models, including or excluding methylation, showed a significant increase in case/control discrimination when considering DNA methylation together with asbestos exposure (AUC = 0.81 versus AUC = 0.89, DeLong's test p = 0.0013). Conclusions: We identified signatures of differential methylation in DNA from whole blood between asbestos exposed MPM cases and controls. Our results provide the rationale to further investigate, in prospective studies, the potential use of blood DNA methylation profiles for the identification of early changes related to the MPM carcinogenic process. (C) 2018 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

Gallbladders from patients affected by both malignant pleural mesothelioma (MPM) and important gallbladder disorders were analyzed to verify the presence of asbestos fibres. Histological thin sections were analyzed by optical microscope and variable pressure scanning electron microscopy coupled with energy dispersive spectroscopy, allowing morphological and chemical characterization of each inorganic phase observed. Fibres of chrysotile and crocidolite, minerals regulated as asbestos, were identified. By immunohistochemical analysis, connective tissue was recognized as the incorporation site. These findings confirm that asbestos fibres can reach the gallbladders of patients with MPM, for whom the development of respiratory diseases confirms asbestos exposure.

Malignant pleural mesothelioma (MPM) is a rare, aggressive cancer caused by asbestos exposure. An inherited predisposition has been suggested to explain multiple cases in the same family and the observation that not all individuals highly exposed to asbestos develop the tumor. Germline mutations in BAPI are responsible for a rare cancer predisposition syndrome that includes predisposition to mesothelioma. We hypothesized that other genes involved in hereditary cancer syndromes could be responsible for the inherited mesothelioma predisposition. We investigated the prevalence of germline variants in 94 cancer-predisposing genes in 93 MPM patients with a quantified asbestos exposure. Ten pathogenic truncating variants (PTVs) were identified in PALB2, BRCA1, FANCI, ATM, SLX4, BRCA2, FANCC, FANCF, PMSI and XPC. All these genes are involved in DNA repair pathways, mostly in homologous recombination repair. Patients carrying PTVs represented 9.7% of the panel and showed lower asbestos exposure than did all the other patients (p = 0.0015). This suggests that they did not efficiently repair the DNA damage induced by asbestos and leading to carcinogenesis.This study shows that germline variants in several genes may increase MPM susceptibility in the presence of asbestos exposure and may be important for specific treatment. (C) 2017 The Authors. Published by Elsevier B.V.

MPM is a deadly cancer whose lethality is almost invariably due to thoracic loco regional progression, whereas distant metastasis (mets) are rarely reported and their prognostic impact remains unclear. The aim of this study is to describe the incidence and patterns of metastatization and to explore their potential prognostic role in a large series of MPM patients (pts) in the highly asbestos polluted area of Casale Monferrato, in the North of Italy. Data from a dedicated MPM database were retrieved and analyzed with MedCalc Statistical Software version 16.1. From 2009/1 to 2016/1, 368 pts (118 females, 250 males), median age 70.5 (range 28 – 91, IQR 63 – 77) were treated at our institution. Pts characteristics were as follows: asbestos exposure certain professional in 147 (40%), certain domestic in 51 (14%), environmental in 170 (56%); PS 0 in 239 (75%), 1 in 95 (26%), ≥ 2 in 34 (9%); histology epithelioid in 271 (74%), biphasic in 50 (14%), sarcomatoid in 46 (12%); stage at diagnosis I – II in 147 (40%), III – IV in 221 (60%). With a median 30 months (mths) follow up, overall survival (OS) was 14.5 mths (95% CI 13.2 – 16.6). Sixty-eight pts (18%, 24 females, 44 males), 51 epithelioid, 11 biphasic and 6 sarcomatoid, had distant mets, of which 13 already had mets at diagnosis (3.5%). The other 55 patients developed mets at a median time-interval of 10 mths (95% CI 7.1 – 12.4) from diagnosis. The most common sites of mets were: lung in 26 pts (7%), peritoneum in 23 (6%), liver in 19 (5%), and bone in 16 (4%). Median OS in mets pts (n = 68) was 19 mths (95% CI 16 – 21.8). Median OS in non-distant mets pts (n = 300) was 13.4 mths (95% CI 11.7 – 15.5). Eighteen % of pts in this series had distant mets, mainly in lung, liver, peritoneum and bone. Distant mets are rarely found at diagnosis (3.5%) but usually are a late event and develop at approximately two-thirds of the natural history of MPM. Acknowledging the limits of the small numbers, our results suggest that distant disease likely does not negatively affect OS compared with loco-regional progression. The longer OS of distant mets patients may indeed suggest a better controlled or a less aggressive thoracic disease.

BAP1 germline mutations predispose to a cancer predisposition syndrome that includes mesothelioma, cutaneous melanoma, uveal melanoma and other cancers. This co-occurrence suggests that these tumors share a common carcinogenic pathway. To evaluate this hypothesis, we studied 40 Italian families with mesothelioma and/or melanoma. The probands were sequenced for BAP1 and for the most common melanoma predisposition genes (i.e. CDKN2A, CDK4, TERT, MITE and POT1) to investigate if these genes may also confer susceptibility to mesothelioma.In two out of six families with both mesothelioma and melanoma we identified either a germline nonsense mutation (c.1153C>T, p.Arg385*) in BAP1 or a recurrent pathogenic germline mutation (c.301G > T, p.Gly101Trp) in CDKN2A.Our study suggests that CDKN2A, in addition to BAP1, could be involved in the melanoma and mesothelioma susceptibility, leading to the rare familial cancer syndromes. It also suggests that these tumors share key steps that drive carcinogenesis and that other genes may be involved in inherited predisposition to malignant mesothelioma and melanoma. (C) 2016 Elsevier Ireland Ltd. All rights reserved.

Introduzione: Il mesotelioma pleurico maligno è una patologia rara, ma con incidenza non trascurabile nelle aree inquinate da amianto. L’istotipo sarcomatoide (SMPM) è caratterizzato da una prognosi particolarmente infausta. Metodologia: Sono state analizzate le caratteristiche e gli outcome clinici di 80 pazienti affetti da SMPM seguiti presso gli Ospedali di Alessandria, Casale Monferrato, Rozzano, Padova. Risultati: Dopo la prima linea chemioterapica è stata osservata risposta parziale (PR) in 2 pazienti (2,5%), stabilità di malattia (SD) in 32 pazienti (40%), progressione di malattia (PD) in 25 pazienti (31%), malattia non valutabile per 21 pazienti (26%). Il time to progression (TTP) è risultato 3.5 mesi; l’overall survival (OS) è stata 7.8 mesi. L’OS dei pazienti che avevano ricevuto pemetrexed è risultata 7.5 mesi vs 8.9 mesi dei pazienti sottoposti a chemioterapia senza pemetrexed (p>0,05). Conclusione: I dati confermano come l’istotipo sarcomatoide abbia una prognosi peggiore rispetto all’epitelioide, con una minor sopravvivenza e una scarsa risposta ai trattamenti. In particolare la chemioterapia standard non ha mostrato efficacia, sottolineando la necessità di altre prospettive terapeutiche nell’ambito di studi clinici incentrati sui nuovi target biomolecolari.

La provincia di Alessandria e soprattutto l’area di Casale Monferrato sono note per l’elevata incidenza di tumori correlati all’amianto, in particolare il mesotelioma. Vi è l’impressione clinica, però, che anche l’incidenza dei tumori del tratto gastroenterico, tra cui i tumori della colecisti, sia più elevata della media nazionale in questa zona, ma non esiste un registro dedicato da cui si possano trarre dati conclusivi. La presenza delle fibre di amianto in campioni tissutali di soggetti con possibile esposizione ambientale e/o domestica ad amianto potrebbe suggerire un loro ruolo nella patogenesi delle malattie tumorali e fornire una valida motivazione per approfondire meglio in quest’area anche l’epidemiologia di altri tumori rari potenzialmente amianto correlati, mediante studi giustificati solo se effettivamente si dimostra la presenza di fibre di amianto negli organi di insorgenza.

ABSTRACT Background Peritoneum is the second most frequent site of origin of malignant mesothelioma (MM). DMPM is the most frequent primary peritoneal malignancy in developed countries. Highly specialized centres have reported improved outcomes following an aggressive loco-regional approach, including cytoreductive surgery (CRS) and perioperative intraperitoneal chemotherapy (PIC), with median overall survival (OS) approaching 50 months and almost 50% relapse-free patients at 5 years. Conversely, in population based studies prognosis still remains very poor with OS in the range of 5.7-10. To describe clinical features and prognosis in unselected consecutive patients, we report on the clinical outcome of a series of DMPM treated at a single Oncological Department, in a highly asbestos-polluted area in Piedmont. Patients and methods By using our database (MesoDB), we retrieved DMPM patients diagnosed between November 1993 and September 2011 at Alessandria and CasaleMonferratoHospitals. All cases were confirmed by the same expert pathologists. Results Among 862 MM we identified 35 patients, 9 F and 26 M. Median age at diagnosis was 67 years, IQR 61-73, range 30-83. Occupational asbestos exposure was definite in 23 and probable in 2 patients, whereas environmental in 10. The histological diagnosis followed a laparoscopic/laparotomic procedure in 25 patients, the other 10 had only US-guided, fine-needle aspiration biopsy. Only 1 patient in the series underwent CRS and PIC. The others were deemed unsuitable for surgery. Ten patients had systemic chemotherapy, 6 pemetrexed and 2 raltritrexed-based. The other 25 received only best supportive care and among these 3 received also subcutaneous IFNbeta or IL2 and 1 intraperitoneal IFNbeta. PFS of the 12 patients receiving systemic therapy was 3.9 months (range 1-7,7). Median OS was 6.1 months (95%CI 2-8,7). Conclusions DMPM accounts for 5% of MMs in our mesoDB, a percentage lower than reported in the literature. Outcomes in our patients were more disappointing compared to those reported by referral centres, but similar to population-based studies. These differences emphasize the strict selection of patients enrolled into aggressive loco-regional treatment programs and the need for new therapeutic approaches suitable for the real clinical practice setting. Disclosure All authors have declared no conflicts of interest.