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N. Van Zandwijk



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    MO09 - Mesothelioma I (ID 120)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track:
    • Presentations: 1
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      MO09.07 - Disease and Patient Characteristics related to Survival in a large population-based cohort of patients with Malignant Pleural Mesothelioma (MPM) (ID 3184)

      16:15 - 17:45  |  Author(s): N. Van Zandwijk

      • Abstract
      • Presentation
      • Slides

      Background
      Despite advances in therapy, the prognosis of MPM remains poor (median overall survival (OS) of 9-12 months). Nevertheless, as described in surgical series, a small proportion of patients survive far longer. Previously identified prognostic factors in patients undergoing extra-pleural pneumonectomy (EPP) include histological subtype, gender and neutrophil-lymphocyte ratio (NLR). Similar factors including stage and performance status have also been shown to be prognostic in chemotherapy studies. We aim to assess in the general MPM patient population, what factors predict for better prognosis independent of the treatment path chosen.

      Methods
      We reviewed records of patients registered (2002 -2009) with the NSW Dust Diseases Board; a government compensation body for NSW workers with occupational asbestos exposure. We evaluated a priori prognostic factors including age, gender, histological subtype, staging on CT imaging and NLR using Kaplan Meier and Cox regression analysis, and by treatment interventions, smoking and asbestos exposure history. Exploratory subgroup analyses compared these factors in long-term (>20 months) survivors versus the remainder of the study population.

      Results
      We identified 913 patients: 90% male; median age 71.9 years; histological subtype (epithelioid 54%; biphasic 11%; sarcomatoid 16.3%; unknown 19%); stage on CT imaging (Tx-I-II 49%; III-IV 51%). 51% of patients received chemotherapy and 6% underwent EPP (of which 67% received chemotherapy. Median age of first occupational asbestos exposure was 18 years, cumulative duration of exposure, 24 years and latency from exposure to diagnosis, 50 years. Median OS was 10.0 months, 15.0 months (range(1-120) in patients receiving chemotherapy and/or EPP and 5.8 months (range 0-125) in patients receiving neither. On univariate analysis, younger age (<70 vs. >70yrs at diagnosis; 13.1 vs. 8.5 months; p<0.001); female gender (12.0 vs. 9.8months; p<0.001); epithelioid subtype (11.8 vs. 7.2 months ;p>0.001); and NLR <5 (12.9 vs. 7.5months; p<0.001) were associated with prolonged OS. Patients who underwent chemotherapy (13.6 vs. 7.2 months; p<0.001) and EPP (17.9 vs. 9.6 months; p<0.001) also had an improved survival. Smoking history (current/ex vs. never) and cumulative asbestos exposure did not affect survival. A trend to improved survival was noted with early stage disease (11.2 vs. 9.1 months; p=0.284) and younger age at first exposure (<18 vs. >18 years of age; 10.9 vs. 9.4 months; p=0.091). On multivariate analysis, age, gender, histological subtype, NLR, EPP and chemotherapy administration remained significant. 24% of patients demonstrated survival over 20 months. Of those, 14% underwent EPP, and 63% received chemotherapy. On multivariate analysis, epithelioid histology (p<0.001), chemotherapy use(p=0.002), undergoing EPP(p=0.01) and NLR<5(p=0.007) were independently associated with survival over 20 months.

      Conclusion
      In this large, population based cohort of MPM patients, we have validated age, gender, histological subtype and NLR as significant prognostic factors. Patients undergoing interventions such as EPP or chemotherapy demonstrated more favourable survival, however it is important to note that 86% of long survivors did not receive radical surgery, and 37% did not receive chemotherapy. As such, we hypothesise that apart from active treatment and inherent selection criteria, there are additional factors, such as favourable tumour biology, that seem to positively influence survival of MPM patients.

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    MO14 - Mesothelioma II - Surgery and Multimodality (ID 121)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Mesothelioma
    • Presentations: 1
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      MO14.07 - Elevated tumour expression of miR-210 is associated with short survival in malignant pleural mesothelioma patients undergoing extrapleural pneumonectomy (ID 1491)

      10:30 - 12:00  |  Author(s): N. Van Zandwijk

      • Abstract
      • Presentation
      • Slides

      Background
      Malignant pleural mesothelioma (MPM) is an aggressive cancer with a median survival of around one year and a 5 year survival rate of less than 10%. A selected group of patients with a potentially resectable tumour mass and good performance status may be considered for extrapleural pneumonectomy (EPP). However the results of this form of treatment are variable. Several prognostic markers have been explored to assist with patient selection including histological subtype, neutrophil-to-lymphocyte ratio (NLR), calretinin and microRNA miR-29c* expression in tumour tissue. In the present study we used microarray profiling to identify other microRNAs which might have the potential to serve as a prognostic biomarker.

      Methods
      The study used 60 formalin-fixed paraffin embedded (FFPE) tumour tissues from MPM patients who underwent EPP and had sufficient tumour for RNA extraction, a series which had been previously used to assess the prognostic value of the NLR. MicroRNA microarray profiling was performed on RNA from the 8 patients with longest (median: 53.7 months) and the 8 patients with shortest (median: 6.4 months) survival. Candidate microRNAs were selected on a basis of biological (>2-fold difference) and statistical (p<0.05) significance, and selected candidates were independently validated in the initial profiling samples using TaqMan assay-based microRNA-specific RT-qPCR. Levels of validated candidates were then assessed by RT-qPCR in 44 additional tumour samples. Overall survival (OS) was calculated from date of EPP and date of death or last follow-up, with patients still alive at last follow-up censored. The median relative expression level of each candidate was used as cut-off to determine high and low expression for examination using the Kaplan-Meier method. Individually significant (p<0.05) variables were entered into a multivariate model together with the established risk factors age, gender, histological subtype, NLR.

      Results
      Microarray profiling identified 12 microRNAs with lower expression in long-term survivors and 4 microRNAs with higher expression in long-term survivors. None of the microRNAs with higher expression in long-term survivors could be validated using RT-qPCR. Of the microRNAs with lower expression in long-term survivors, miRs-30e, -93, -106b, -210, and -222 were validated by RT-qPCR in the same samples used for the profiling and found to be significantly different between long-term and short-term survivors. The expression levels of miR-30e and miR-210 showed a significant association with survival. MiR-30e: median OS of 24.2 months for low expression vs 13.3 months for high expression (p=0.03); miR-210: median OS of 24.2 months for low expression vs 13.7 months for high expression (p=0.008). In addition, both gender and histological subtype were significant prognostic factors using a univariate model. Multivariate analysis with age, gender, histological subtype, NLR and microRNA expression included as variables revealed that miR-210 was the only factor remaining significant (p= 0.006; hazard ratio: 0.41; 95% CI: 0.2-0.85).

      Conclusion
      This study has identified expression of miR-210 as a potential new prognostic factor for patients undergoing EPP. Further validation is needed, but this marker has the potential to assist in better selection of patients considered for radical surgery of MPM.

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    P2.06 - Poster Session 2 - Prognostic and Predictive Biomarkers (ID 165)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
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      P2.06-017 - Long non coding RNAs (lncRNAs) are dysregulated in malignant pleural mesothelioma (MPM) (ID 1524)

      09:30 - 16:30  |  Author(s): N. Van Zandwijk

      • Abstract

      Background
      Malignant Pleural Mesothelioma (MPM) is an aggressive disease, often diagnosed at an advanced stage. It is characterized by a long latency period and prior asbestos exposure. Currently accurate diagnosis of MPM is difficult due to the lack of sensitive biomarkers, and despite minor improvements in treatment, median survival rates rarely exceed 12 months. Accumulating evidence suggests that aberrant expression of long non-coding RNAs (lncRNAs) plays an important functional role in cancer biology. LncRNAs are a class of recently discovered non-protein coding RNAs >200 nucleotides in length with a role in regulating transcription. The aims of this study were to characterize the expression and function of these lncRNAs in MPM.

      Methods
      To identify novel lncRNAs involved in MPM, microarray profiling was performed on five cell lines - the immortalized normal mesothelial cell line (MeT-5A) and four MPM lines (two epithelioid H28 and H226 and two biphasic MM05 and MSTO) using Invitrogen’s NCode lncRNA microarrays. These allow simultaneous assessment of mRNA and lncRNA content. High priority candidate lncRNAs were selected on the basis of statistical (P<0.05) and biological (>3-fold difference) significance. Expression of high priority candidates were technically validated using RT-qPCR, and biologically validated in three independent test sets. Pathway analyses were performed to interrogate the relationship between lncRNA and mRNA expression. Cell proliferation and colony formation assays were used to investigate lncRNA function.

      Results
      Microarray profiling and real-time qPCR validation identified 9 lncRNA candidates with significant differential expression in MPM compared with normal mesothelial cells Validation in three independent test sets by RT-qPCR analysis demonstrated consistent up-regulation of four of these lncRNAs. Receiver Operating Curve analysis showed that two of these candidates were able to separate benign pleura and MPM with high sensitivity and specificity. In addition, high expression of AK054908 was associated with nodal metastases with lower levels of AK130275 and AF268386 observed in patients receiving induction chemotherapy. Cases with higher EF177379 levels also demonstrated a trend to improved survival. The majority of mRNAs co-expressed with candidate lncRNAs were associated with cellular and metabolic processes including cell cycle, cell death and apoptosis. In functional studies, siRNA knockdown of AK130275 showed suppression of cell growth and colony formation in MPM cells with moderate changes observed following knockdown of EF177379.

      Conclusion
      To our knowledge this is the first systematic study of lncRNA expression profiles in MPM. We have found that lncRNA expression profiles can distinguish malignant mesothelium from normal pleural tissue, and that some lncRNAs are associated with nodal metastasis and long term survival. We also demonstrate that lncRNAs have potential prognostic and diagnostic utility with functional roles in regulating cell growth. Further work is required to evaluate whether these lncRNAs are capable of differentiating mesothelioma from lung cancer and benign asbestos-related diseases, and to reveal their specific functions in MPM pathogenesis.

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    P3.01 - Poster Session 3 - Cancer Biology (ID 147)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
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      P3.01-008 - The importance of the Secreted Frizzled-Related Protein (SFRP) tumour suppressor gene family and the effect of long-term asbestos exposure on SFRP expression in malignant pleural mesothelioma (MPM) (ID 3495)

      09:30 - 16:30  |  Author(s): N. Van Zandwijk

      • Abstract

      Background
      The etiology of malignant pleural mesothelioma (MPM) is closely linked with asbestos exposure. Asbestos is capable of inducing chronic inflammation which potentiates tumour suppressor gene silencing. Epigenetic silencing of the Wnt pathway, well characterized in the progression of colon cancer, is associated with chronic inflammation. As antagonists of Wnt pathways, the SFRPs are functional tumour suppressors of colon, gastric, breast, ovarian and lung cancers, with some members methylated in mesothelioma. In this study, we aimed to investigate the functional significance of the SFRP2 and 5 in MPM, and the effect of long-term asbestos exposure on epigenetic alteration in the immortalised mesothelial cell MeT-5A.

      Methods
      Gene expression and promoter DNA methylation of the SFRP family were analysed in MPM lines and MeT-5A with and without 5’Azacitidine treatment using RT-qPCR, MSP and COBRA. The effect of SFRP2 and SFRP5 re-expression on MPM cells was determined by cell growth and clonogenic assays in 2D and 3D culture. The expression and promoter DNA methylation of SFRP genes was also assessed in MPM patient samples using RT-qPCR and MSP. MeT-5A cells were cultured long-term (12 months) in the presence of asbestos, and SFRP mRNA expression and promoter DNA methylation was analysed.

      Results
      SFRP2 and SFRP5 were either absent or down-regulated MPM lines, and restored after 5’Azacitidine treatment. SFRP1 was highly expressed and unmethylated in MeT-5A line. Expression of the SFRP family was down-regulated in MPM patient samples and this correlated with methylation of promoter CpG islands. Ectopic expression of SFRP2 or SFRP5 inhibited MPM cell growth and colony formation in both 2D and 3D culture. SFRP1 was down-regulated and methylated following prolonged asbestos exposure in MeT-5A cells.

      Conclusion
      Our results indicate that both SFRP2 and SFRP5 function as tumour suppressor genes in MPM and long-term asbestos exposure induce gene silencing via DNA hypermethylation.