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R. Harvie



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    MO01 - Lung Cancer Biology - Techniques and Platforms (ID 90)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Biology
    • Presentations: 1
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      MO01.08 - Identifying Strategies For The Treatment Of Acquired EGFR Tyrosine Kinase Inhibitor Resistance (ID 3187)

      10:30 - 12:00  |  Author(s): R. Harvie

      • Abstract
      • Presentation
      • Slides

      Background
      The management of non-small cell lung cancer (NSCLC) is becoming increasingly personalised with the identification of oncogenic drivers of cancer cell growth which are able to be targeted therapeutically. The paradigm of advanced non-squamous NSCLC treatment now incorporates assessment of epidermal growth factor (EGFR) mutations and treatment with EGFR tyrosine kinase inhibitors (TKIs) in cases where sensitising mutations are found, which results in significant prolongation of progression-free survival compared to empirical chemotherapy. However, the emergence of acquired resistance to EGFR TKIs is almost universal and the two most common mechanisms of resistance include the acquisition of a second mutation in EGFR, the T790M mutation, and c-MET amplification. Approximately one-quarter of cases of resistance are yet to be defined mechanistically and furthermore, optimal subsequent treatment remains unknown. Further research is required to understand the molecular origins of the development of acquired resistance in order to develop rational treatment strategies that incorporate both targeted and cytotoxic therapies. This study is evaluating, using in vitro models, pathways involved in the development of acquired resistance to EGFR TKI and chemotherapy and evaluating critical differences according to EGFR mutation status.

      Methods
      A panel of human NSCLC cell lines with varying clinically relevant molecular characteristics is being assessed and used to develop resistance to various cytotoxic agents and EGFR TKIs, through chronic low dose exposure, as outlined in the table below:

      Cell Line Mutation Status EGFR TKI Sensitivity Resistant Cell Line Generated
      HCC827 EGFR Exon 19 deletion Sensitive Erlotinib; Cisplatin; Paclitaxel; Pemetrexed
      H1975 EGFR Exon 21 Point Mutation (L858R) and T790M mutation Resistant Cisplatin; Paclitaxel; Pemetrexed
      H1299 EGFR Wild-Type Resistant Cisplatin; Paclitaxel; Pemetrexed
      A549 EGFR Wild-Type and KRAS Mutation Resistant Cisplatin; Paclitaxel; Pemetrexed, HDAC-inhibitor
      Assessments of proliferation, cytotoxicity and key signalling pathways are being conducted to evaluate mechanisms of chemotherapeutic and targeted therapy resistance.

      Results
      Chronic low dose exposure has been successful in generating resistant cell lines to both chemotherapeutic agents and the EGFR TKI erlotinib. Cross-resistance to taxol in cisplatin-resistant cell lines has been observed, along with evidence of epithelial-to-mesenchymal transition in the development of EGFR TKI resistance. Antibody arrays of key signalling pathways are being conducted to confirm critical pathways of interest.

      Conclusion
      The panel of human NSCLC cell lines with parental lines harbouring various EGFR sensitising and resistance mutations and generated lines resistant to cytotoxic agents and EGFR TKI are a useful in vitro model to understand key pathways involved in the emergence of therapeutic resistance and to understand how both sensitising and resistant EGFR mutations influence response to cytotoxic agents. This will guide treatment strategies selected for evaluation in vivo that may influence future treatment selection for patients.

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    P2.05 - Poster Session 2 - Preclinical Models of Therapeutics/Imaging (ID 158)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
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      P2.05-011 - Characterisation of chemo-resistant syngeneic orthotopic rat pre-clinical models of mesothelioma. (ID 1718)

      09:30 - 16:30  |  Author(s): R. Harvie

      • Abstract

      Background
      Malignant mesothelioma is an aggressive cancer with a low response to current therapies and consequently a poor prognosis. There is an urgent need to identify novel and more effective treatments to improve survival and quality of life for patients with mesothelioma. While a number of novel therapeutic agents have recently been examined in clinical trials, to date none of these has resulted in changes to standard management. This is due in part to a lack of robustness and relevance of the pre-clinical models used to assess new treatments. Therefore validated and biologically relevant pre-clinical models that demonstrate the clinical behaviour and drug sensitivity of mesothelioma, as well as typical resistance mechanisms, are necessary to improve the discovery of new treatments. Here we describe the generation and evaluation of chemotherapy resistant pre-clinical models of mesothelioma derived from the previously utilized syngeneic II-45 rat mesothelioma model.

      Methods
      Cell lines resistant to the current standard of care agents: cisplatin, pemetrexed gemcitabine, vinorelbine, and cisplatin and pemetrexed in combination, were generated by 15 rounds of exposure to the respective agent. Normal rat mesothelial cells (4/4 RM.4), the parental II-45 and the 5 resulting chemo-resistant mesothelioma cell lines were characterised for resistance to these and other agents. Tumours arising from syngeneic pleural engraftment of these cell lines were assessed by size, morphology, immunohistochemical markers of human malignancy, chromosomal changes and expression of genes involved in drug resistance and metabolism. Engrafted rats were assessed for survival, and circulating haematological, cytokine and biomarker profiles were generated and compared.

      Results
      Five different II-45 cell lines with approximately 2-fold resistance to the chemotherapeutic agent they were repeatedly exposed to, were established (cisplatin, p < 0.05; pemetrexed, gemcitabine, vinorelbine, p < 0.001). Cross resistance to other classes of anti-cancer agents also developed indicating potential multi-drug resistant phenotypes. Tumours derived from both the parental and chemo-resistant cell lines were immunohistochemically indistinct from human mesothelioma with positive labeling for WT1, calretinin, HBME-1, cytokeratin and popoplanin and negative labeling for two carcinoma related markers TTF-1 and CD15. Homozygous deletion of p16[INK4A]/p14[ARF], and increased expression of several members of the ATP-binding cassette transporter superfamily and Androgen receptor (AR) were demonstrated, consistent with findings in human mesothelioma. Corresponding with biomarkers studies in human disease, increased levels of osteopontin (p < 0.01), mesothelin (p < 0.01), vascular endothelial growth factor (p < 0.001) and neutrophil to lymphocyte ratio were identified relative to control bloods. Further, the acquisition of chemo-resistance resulted in changes to tumour morphology with tumours ranging from essentially epithelioid in the gemcitabine resistant tumours to entirely sarcomatoid in the combination (cisplatin and pemetrexed) resistant tumours. Overall survival was also affected by the acquisition of resistance with rats with pemetrexed resistant tumours having decreased survival.

      Conclusion
      These models display many features corresponding with the human disease, and thus provide powerful and robust pre-clinical platforms for in vivo mesothelioma studies.

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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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      P2.06-015 - Novel plasma proteins associated with prognosis in malignant pleural mesothelioma (ID 1337)

      09:30 - 16:30  |  Author(s): R. Harvie

      • Abstract

      Background
      The search for novel biomarkers to define more successful and individual treatment approaches represent an important challenge for those involved in the care for patients with malignant pleural mesothelioma (MPM). In this exploratory study, we have systematically investigated the proteins present in plasma of MPM patients and correlated their levels with disease outcomes.

      Methods
      Plasma samples from twelve MPM patients (6 ‘short-’ and 6 ‘long-term’ survivors from parallel phase II studies investigating thalidomide) were used for proteomic analyses. Our series included samples from 9 patients with epithelial MPM and 3 patients with biphasic MPM. Plasma samples were immuno-depleted of the 14 most abundant proteins prior to labelling for isobaric tag for relative and absolute quantitation (iTRAQ) analysis using mass spectrometry. The most promising candidates and mesothelin were chosen for selected reaction monitoring mass spectroscopy (SRM-MS) quantification and enzyme-linked immunosorbent assay (ELISA) validation. Statistical analyses using T-Test of peak areas were used to identify proteins that were differentially expressed between the short- and long-term survivor groups.

      Results
      Median survival of short- and long-term survivors (1.2 and 38.3 months, respectively) differed significantly (p = 0.001). This was also the case for the neutrophil-to-lymphocyte ratio (NLR) that was significantly higher in the group of short-term survivors (p=0.03). Other baseline characteristics did not reveal major differences between the short- and long-term survivors. The total number of proteins identified was 226 (1% false discovery rate) in iTRAQ. A number of those were found to be differentially expressed between short- and long-term survivors (≥1.2-fold change; p≤0.05) by iTRAQ: selenoprotein P; tetranectin; insulin-like growth factor-binding protein 2 (IBP2); osteonectin (SPARC); platelet basic protein (CXCL7); and attractin. Mesothelin was assessed to validate the proteomic methodology: SRM-MS quantification was highly correlated with the MESOMARK ELISA values with a Pearson correlation of 0.82 (p=0.001). SRM-MS quantification revealed that the concentrations of attractin (p=0.02), tetranectin (p=0.003) and selenoprotein P (p=0.001) were higher in long-term survivors. In contrast, there was a trend for an increase in the concentration of SPARC (p=0.32), IBP2 (p=0.12) and CXCL7 (p=0.19) to be correlated with shorter survival. Furthermore, quantification by ELISA demonstrated an association between long survival and low concentration of SPARC (p=0.07) as well as high tetranectin (p=0.13).

      Conclusion
      We have demonstrated the feasibility of using the iTRAQ and SRM-MS proteomic techniques to investigate potential prognostic protein markers in plasma of MPM patients. Potential prognostic biomarkers worthy of further studies include SPARC and tetranectin and we plan to validate these in a larger clinical cohort.