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M.P. Barr
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MA02 - RNA in Lung Cancer (ID 377)
- Event: WCLC 2016
- Type: Mini Oral Session
- Track: Biology/Pathology
- Presentations: 1
- Moderators:E. Brambilla, M. Noguchi
- Coordinates: 12/05/2016, 14:20 - 15:50, Stolz 2
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MA02.02 - A Novel 5-miR Signature Shows Promise as a Diagnostic Tool and as a Predictor of Cisplatin Response in NSCLC (ID 5948)
14:26 - 14:32 | Author(s): M.P. Barr
- Abstract
Background:
MicroRNAs are a class of small non-coding RNAs that range in size from 19-25 nucleotides. They have been shown to regulate a number of processes within tumour biology, including metastasis, invasion and angiogenesis. More recently, miRNAs have been linked to chemoresistance in solid tumours, including lung cancer.
Methods:
MicroRNA expression within an isogenic panel of age-matched parent (PT) and cisplatin resistant (CisR) NSCLC cell lines was profiled using the 7[th] generation miRCURY LNA arrays (Exiqon). Significantly altered miRNAs within the CisR sublines were manipulated using antagomirs (Exiqon) and Pre-miRs (Ambion) and functional studies were carried out in the presence and absence of cisplatin. To examine the translational relevance of these miRNAs, their expression was examined in a cohort of chemo-naïve patient-matched normal and lung tumour tissue and serum from NSCLC patients of different histologies. To create a xenograft model of cisplatin resistance 1x10[3 ]cells H460 PT or CisR cells were injected into 5-7week old NOD/SCID mice. Tumour volume was measured over time and harvested once the tumour mass measured 500mm[3] and formalin-fixed and paraffin embedded (FFPE). Expression of the 5-miR signature was analysed within FFPE murine tumours and cisplatin resistance was investigated relative to cisplatin sensitive controls.
Results:
Profiling and subsequent validation revealed a 5-miR signature associated with our model of cisplatin resistance (miR-30a-3p, miR-30b-5p, miR-30c-5p, miR-34a-5p, miR-4286). Inhibition of the miR-30 family and miR-34a-5p reduced clonogenic survival of CisR cells when treated cisplatin. Expression of the miRNA signature was significantly altered in both adenocarcinoma (AD) and squamous cell carcinoma (SCC) relative to matched normal lung tissue and between SCC and AD tissue. miR-4286 was significantly up-regulated in SCC sera compared to normal control and AD sera. Similarly to the cell line expression of the miRNAs, the miR-30 family members and miR-34a-5p were up-regulated in the CisR xenograft FFPE tissue relative to PT.
Conclusion:
A novel miRNA signature associated with cisplatin resistance was identified in vitro, genetic manipulation of which altered clonogenic response to cisplatin. The 5-miR signature shows both diagnostic and prognostic biomarker potential across a number of diagnostically relevant biological mediums.
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P2.01 - Poster Session with Presenters Present (ID 461)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Biology/Pathology
- Presentations: 2
- Moderators:
- Coordinates: 12/06/2016, 14:30 - 15:45, Hall B (Poster Area)
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P2.01-031 - CCL Chemokines May Play an Important Role in Cisplatin Resistance (ID 4861)
14:30 - 14:30 | Author(s): M.P. Barr
- Abstract
Background:
In the absence of a targetable mutation, cisplatin based chemotherapy is the backbone of NSCLC treatment. However, a diverse patient population combined with complex tumour heterogeneity is hampering its’ clinical utility. Although intrinsic and acquired resistance to cisplatin is common, the mechanisms have not yet been fully elucidated. However, some studies have suggested that inflammatory pathways may play a key role in chemo-resistance. The aim of this project is to increase our understanding of inflammatory mediated cisplatin resistance in NSCLC.
Methods:
A number of isogenic cell line models of NSCLC (adenocarcinoma, squamous cell carcinoma, large cell carcinoma) cisplatin resistance were utilised to assess the role of inflammation in chemo-resistance. These included a sensitive parental cell line (PT) and a matched resistant subtype (CisR). The cell lines were screened for NFKB and a number of inflammatory mediators including chemokines and TLRs at the mRNA (RT-PCR/qPCR) and protein level (Western Blot/ELISA). A specific NFKB inhibitor, DHMEQ, and recombinant chemokines were employed to further characterise inflammatory pathways in PT and CisR cells in terms of cisplatin sensitivity, proliferation (BrdU ELISA), cellular viability (Cytell Cell Imaging System) and DNA damage response (Comet). An in vivo study was also completed using DHMEQ alone and in combination with cisplatin.
Results:
A number of NFKB targets and responsive pathways are deregulated in CisR cells compared with their matched sensitive PT cell line. Amongst others, CCL2 and CCL5 were altered across all NSCLC subtypes. Preliminary data suggests that DHMEQ enhances cisplatin sensitivity in both PT and CisR cells, conversely recombinant chemokines elicit a protective effect. Additionally, DHMEQ treatment resulted in opposite affects on CCL2 and CCL5 mRNA levels in the PT and CisR cell lines. This may reflect an alternative pathway hierarchy within the cells. Further characterisation is ongoing assessing chemokine specific inhibitors. Although, in vivo data suggests a trend of decreased tumour growth in the DHMEQ cohorts compared with vehicle control, the data was not significant. However, tumour samples appeared more necrotic with DHMEQ and are currently being characterised using IHC for necrosis and proliferation.
Conclusion:
Targeting chemokines downstream of NFKB may provide a means to overcome inflammatory mediated acquired and intrinsic NSCLC chemo-resistance. Given the increased significance of immuno-oncology agents to harness the body’s own immune system in the fight against cancer, these agents may also prove fruitful in re-sensitising patients to chemotherapy.
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P2.01-066 - PD-L1 Tumor Expression and Its Effect on Overall Survival among Patients with Resected Non-Small Cell Lung Cancer (NSCLC) (ID 6110)
14:30 - 14:30 | Author(s): M.P. Barr
- Abstract
Background:
Anti-PD1 monoclonal antibodies have demonstrated survival advantage over conventional chemotherapy in progressive metastatic non-small cell lung cancer (NSCLC). The prognostic role of tumoral expression of PD-L1 in NSCLC remains conflicting. We performed this study to evaluate the impact of PD-L1 expression as a prognostic marker in non-metastatic NSCLC.
Methods:
NSCLC patients (pts) who underwent curative resection between 1998 and 2006 in St. James’s Hospital, Dublin were included. PD-L1 status was assessed using Ventana SP124 antibody on archival FFPE surgical tumor specimens, arrayed on tissue microarrays (TMAs) with triplicate 0.6 mm cores. PD-L1 was scored as positive if membranous staining was present in >1% of tumor cells aggregated across the replicate cores to address heterogeneity. Clinical characteristics of the pts were obtained from the hospital electronic database including age, gender, histological subtype, smoking status, grade, tumor size, nodal status, stage and survival data.
Results:
One-hundred and forty-seven patients from our institutional database were included, of which 92 (63.0%) were males, with a median age of 65 years (range: 42-82). 53.1% (n=78) with squamous histological subtype, 43.5% (n=60) were ex-smoker and 50.3% (n=74) had Stage I disease. PD-L1 positivity vs negativity among non-smoker, ex-smoker and current smoker were 13.0% vs 20.9%, 47.8% vs 43.3% and 39.1% vs 35.8% respectively, (p=0.708). PD-L1 expression by IHC was significantly higher in squamous NSCLC compared to non-squamous NSCLC (34.7% vs 14.6%, p=0.030). We also noted increased PD-L1 positivity with rising tumor T stage (T1 vs T2 vs T3 vs T4: 7.1% vs 30.6% vs 0% vs 60%, p=0.023) and grade of differentiation (G1 vs G2 vs G3: 11.1% vs 19.6% vs 44%, p=0.039). There was no correlation between nodal status and PD-L1 expression (N0 vs N1 vs N2: 25.5% vs 25% vs 26.3%, p=0.995). PD-L1 expression appears to be independent of overall disease stage (I vs II vs III: 27.3% vs 22.7% vs 25.0%, p=0.921). The median overall survival for PD-L1 positive vs negative pts was 22.1 vs 20.8 months with HR of 0.64 (95% CI: 0.34-1.12, p=0.123). Overall survival rates of pts with PD-L1 positive vs negative tumors at 2 years were 47.8% vs 44.8% and at 5 years were 43.5% vs 26.9%.
Conclusion:
In our cohort, PD-L1 expression was not associated with poorer survival among resected NSCLC pts. Tumour size and grade of differentiation appear to correlate with PD-L1 expression which warrants further validation in future studies.
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P2.03a - Poster Session with Presenters Present (ID 464)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Advanced NSCLC
- Presentations: 3
- Moderators:
- Coordinates: 12/06/2016, 14:30 - 15:45, Hall B (Poster Area)
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P2.03a-062 - Characterisation and Targeting of the DNA Repair Gene, XRCC6BP1, in Cisplatin Resistant NSCLC (ID 5198)
14:30 - 14:30 | Author(s): M.P. Barr
- Abstract
Background:
In the absence of specific treatable mutations, platinum-based doublet chemotherapy remains the gold standard treatment for NSCLC patients. However, its clinical efficacy is hindered in many patients due to intrinsic and acquired resistance to these agents, in particular cisplatin. Alterations in the DNA repair capacity of damaged cells is now recognised as an important factor in mediating this phenomenon.
Methods:
DNA Repair Pathway RT[2 ]Profiler Arrays were used to elucidate key DNA repair genes implicated in chemoresistant NSCLC cells using cisplatin resistant (CisR) and corresponding parental (PT) H460 cells previously established in our laboratory. DNA repair genes significantly altered in CisR cells were validated at the mRNA and protein level, using RT-PCR and Western blot analysis, respectively. The translational relevance of differentially expressed genes was examined in a cohort of chemo-naïve matched normal and tumour lung tissues from NSCLC patients. Loss of function studies were carried out using siRNA technology. The effect of XRCC6BP1 gene knockdown on apoptosis was assessed by FACS using Annexin-V/PI staining. Cellular expression and localisation of XRCC6BP1 protein and γH2AX foci in response to cisplatin were examined by immunofluorescence using the Cytell™ Imaging System. To investigate a role for XRCC6BP1 in lung cancer stem cells, Side Population (SP) studies were used to characterise stem-like cells in chemoresistant cells. XRCC6BP1 mRNA analysis was also examined in ALDH1[+] and ALDH1[- ]subpopulations.
Results:
We identified a number of critical DNA repair genes that were differentially regulated between H460 PT and CisR NSCLC cells, where XRCC6BP1 mRNA and protein expression was significantly increased (mRNA; 19.4-fold) in H460 CisR cells relative to their PT counterparts. Relative to matched normal lung tissues, XRCC6BP1 mRNA was significantly increased in lung adenocarcinoma patients. Gene silencing of XRCC6BP1 induced significant apoptosis of CisR cells and reduced the DNA repair capacity of these cells relative to scrambled (negative) controls. Immunofluorescence studies showed an increase in XRCC6BP1 protein expression and γH2AX foci in CisR cells relative to their PT counterparts. SP analysis revealed a significantly higher stem cell population in CisR cells, while XRCC6BP1 mRNA expression was considerably increased in SKMES-1, H460 and H1299 ALDH1[+] CisR cells compared to ALDH1[-] cells.
Conclusion:
We identified XRCC6BP1 as key DNA repair gene implicated in cisplatin resistant NSCLC. Our data highlight the potential of targeting components of the DNA repair pathway in chemoresistant lung cancer, in particular, XRCC6BP1, either alone or in combination with conventional cytotoxic therapies.
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P2.03a-063 - Small Molecule Cancer Stemness Inhibitor, BBI608, Restores Cisplatin Sensitivity in Resistant NSCLC (ID 5962)
14:30 - 14:30 | Author(s): M.P. Barr
- Abstract
Background:
The cancer stem cell (CSC) hypothesis is now a well-established and widely investigated field within oncology. It hypothesizes that there is a robustly resistant stem-like population of cells that survive initial chemotherapeutic treatment. These surviving CSCs contribute to the recapitulation of a heterogeneous tumour via a combination of asymmetric and symmetric cell division, subsequently resulting in relapse and therapeutic resistance. BBI608 is a small molecule inhibitor of cancer stemness; it targets STAT3, leading to the inhibition of critical genes required for the maintenance of cancer stemness. To date, preclinical studies investigating BBI608 in in vitro and in vivo models of pancreatic and prostate cancer have shown promise.
Methods:
Aldefluor (Stemcell Technologies) staining and flow cytometry analysis of an isogenic panel of matched parent (PT) and cisplatin resistant (CisR) NSCLC cell lines identified the ALDH1-positive (ALDH1+ve) subpopulation of cells as a key CSC subset across cisplatin resistant NSCLC cell lines. PT and CisR cell lines were treated with BBI608 (1μM) and stemness factors investigated, the presence of the ALDH1+ve CSC population was reassessed by flow cytometry and expression of stemness factors (Nanog, Oct-4, Sox-2, Klf4 and cMyc) were examined by reverse transcriptase PCR. The functional parameters of proliferation, clonogenic survival and apoptosis were investigated with increasing concentrations of cisplatin (0-100μM) in the presence and absence of 1μM BBI608.
Results:
The NSCLC CisR sublines showed a significantly greater ALDH1+ve CSC population relative to their PT counterparts. Treatment of the CisR sublines with 1μM BBI608 significantly depleted the ALDH1+ve CSC population and decreased gene expression of stemness markers. BBI608 significantly decreased the proliferative capacity and clonogenic survival of the CisR sublines when in combination with cisplatin relative to cisplatin alone. Cisplatin in combination with BBI608 significantly increased cisplatin-induced apoptosis in the CisR sublines indicating restoration of cisplatin sensitivity.
Conclusion:
To date, BBI608 has not been investigated in terms of a cisplatin resistant CSC population in lung cancer. BBI608, via the inhibition of STAT3, pharmacologically depleted the CSC subpopulation and stemness expression while simultaneously restoring cisplatin sensitivity. There are currently a number of clinical trials recruiting patients to further investigate BBI608. These data suggest a promising role for BBI608 in the treatment of non-responsive or recurrent NSCLC.
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P2.03a-064 - Inhibition and Exploitation of Aldehyde Dehydrogenase 1 as a Cancer Stem Cell Marker to Overcome Cisplatin Resistant NSCLC (ID 5954)
14:30 - 14:30 | Author(s): M.P. Barr
- Abstract
Background:
The root of therapeutic resistance is hypothesized to be the presence a rare CSC population within the tumour population which survives chemotherapeutic treatment and has the potential to recapitulate a heterogenic tumour. Aldehyde dehydrogenase 1 (ALDH1) is involved the catalytic conversion of vitamin A (retinol) to retinoic acid and has been identified as a CSC marker in a number of solid malignancies.
Methods:
FACS analysis of an isogenic panel of matched parent (PT) and cisplatin resistant (CisR) NSCLC cell lines identified ALDH1 as a promising CSC-marker associated with cisplatin resistance across NSCLC histologies. The H460 CisR subline was separated by FACS into ALDH1-positive and negative subpopulations and subcutaneously injected into NOD/SCID mice to assess tumour initiation and growth. ALDH1 was inhibited in vitro within the cell lines using two pharmacological ALDH1 inhibitors, DEAB and disulfiram, alone and in combination with cisplatin. Cell lines were treated in vitro with retinol and all-trans retinoic acid (ATRA) to exploit the vitamin A/retinoic acid axis in which ALDH1 is involved.
Results:
The CisR sublines showed significantly greater ALDH1 activity relative to their PT counterparts. In vivo subcutaneous injection of ALDH1-positive and negative subpopulations revealed no significant difference in tumour initiation or growth rate. ALDH1 inhibition in combination with cisplatin significantly decreased clonogenic and proliferative competencies and increased apoptosis cell death compared to cisplatin alone. Vitamin A supplementation and ATRA treatment in combination with cisplatin showed similar re-sensitising effects.
Conclusion:
This pharmacological CSC depletion in conjunction with cisplatin treatment resulted in re-sensitisation of cisplatin resistant cells to the cytotoxic effects of cisplatin. These data suggest vitamin A supplementation or the addition of ATRA or an ALDH1 inhibitor to the cisplatin-based chemotherapeutic regimen may be of clinical benefit in overcoming tumour recurrence and cisplatin resistance.
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P2.03b - Poster Session with Presenters Present (ID 465)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Advanced NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 12/06/2016, 14:30 - 15:45, Hall B (Poster Area)
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P2.03b-096 - Utilisation of a Novel 3D Culture Technology for the Assessment of Chemo-Resistance in Non-Small Cell Lung Cancer (ID 4954)
14:30 - 14:30 | Author(s): M.P. Barr
- Abstract
Background:
Elucidation of the key mechanisms underlying resistance to chemotherapy is an on-going and complex process. Owing to its suggested increased biological relevance, many are now transitioning from two-dimensional (2D) to three-dimensional (3D) cellular-based assay systems. These systems permit the formation of 3D multicellular structures (MCS). The internal micro-environment of these structures mimics closely those found in vivo. In addition they are considered to provide a more biologically relevant model of chemo-resistance. This study focuses on the utilisation of a novel 3D culture technology to compare chemo-resistant models of non-small cell lung cancer (NSCLC) in 3D culture with those cultured in 2D monolayers. Critically, this will provide a valuable tool to determine the biological discrepancies which exist between the two culture methods with the aim to identify novel mechanisms of chemo-resistance in NSCLC.
Methods:
Isogenic NSCLC models of cisplatin resistance, which encompassed sensitive parent (PT) and matched cisplatin resistant (CisR) cell lines, were used for this study. The 3D MCS were cultured in Happy Cell Advanced Suspension Medium™ and 2D monolayers as standard. Both 2D and 3D cultures were exposed to a range of cisplatin concentrations (0 – 100 µM) for a period of 72 h. Subsequently, cellular viability, hypoxia, proteomic and morphological assays were conducted in order to compare the response of both PT and CisR cells in 2D and 3D.
Results:
High content imaging has identified a central necrotic core within the 3D MCS, which is a feature of the asymmetric growth patterns observed in vivo; that being a decrease in viable cells as you move inwards from the periphery of the MCS. Preliminary data suggests that at equivalent cisplatin concentrations, H460 3D MCS exhibit increased resistance to cisplatin compared with 2D monolayers in both PT and CisR cell lines. Proteomic analysis has also identified diverse pathway modifications in 3D compared with 2D culture, with a number of proteins expressed exclusively in each. Additional cellular characterisation and further bioinformatic analysis is on-going.
Conclusion:
Chemotherapeutic intervention is most frequently employed in the treatment of NSCLC, however many patients exhibit intrinsic and acquired resistance to common chemotherapy drugs, such as cisplatin and targeted agents. As it has been argued that 3D models and their micro-environment are more reflective of the in vivo situation, 3D culture may provide a more accurate in vitro model to elucidate mechanisms of chemo-resistance and possibly aid in the identification of novel targets to re-sensitise and stratify patients for therapy.
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P3.01 - Poster Session with Presenters Present (ID 469)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Biology/Pathology
- Presentations: 2
- Moderators:
- Coordinates: 12/07/2016, 14:30 - 15:45, Hall B (Poster Area)
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P3.01-042 - Lung Cancer Cells Can Stimulate Functional and Genotypic Modifications in Normal Bronchial Epithelial Cells (ID 4852)
14:30 - 14:30 | Author(s): M.P. Barr
- Abstract
Background:
Normal lung epithelium cells may act in concert with tumour cells, given that bystander effects may exist between the two. This interaction may lead to inappropriate activation of pro-oncogenic signalling pathways, which may result in high mutational load and tumour heterogeneity. The aim of this project is to evaluate the effects of non-small cell lung cancer (NSCLC) cells on an immortalised normal bronchial epithelial cell line.
Methods:
A normal bronchial epithelial cell line (HBEC4) was exposed to A549 (adenocarcinoma), H460 (large cell carcinoma) and SK-MES-1 (squamous cell carcinoma) NSCLC cell lines in a trans-well co-culture system. Cellular characteristics were examined using a Cytell Cell Imaging System (cell number, viability, apoptosis, cell cycle). The gene expression profile was also determined in terms of inflammatory mediators, stem cell markers (RT-PCR) and miRNA profiling (Nanostring). The proliferative effect of NSCLC cancer exosomes was also examined (BrdU ELISA) on the HBEC4 cell line.
Results:
A number of functional and gene modifications were observed in the HBEC4 cell line after seven days of co-culture. While patterns were similar amongst all NSCLC subtypes, SK-MES-1 elicited the most significant effects in terms of cell number, viability, cell cycle progression and proliferative potential of isolated cancer exosome fraction. Promotion of both inflammatory mediators and stem cell marker expression was evident at the mRNA level. There was no apparent consensus between NSCLC subtypes and miRNA expression, as exposure to each cell line resulted in distinct profiles of miRNAs in HBEC4 cells. Bioinformatic analysis of miRNA target genes, demonstrated that pathways such as p53, MAPK, VEGF, TLR and Wnt were amongst those altered.
Conclusion:
Cancer cells may promote significant genotypic and phenotypic alterations within the normal lung epithelium though multiple mechanisms. These modifications may, in part, contribute to the heterogeneity of lung cancer tumours and influence response to both chemotherapeutics and targeted agents.
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P3.01-064 - The Overexpression and Cleavage of SASH1 by Caspase-3 Stimulates Cell Death in Lung Cancer Cells (ID 5811)
14:30 - 14:30 | Author(s): M.P. Barr
- Abstract
Background:
SASH1 (SAM and SH3 domain-containing protein 1) is a recently identified gene with tumour suppressor properties and has a role in induction of apoptosis. Previous work has shown that 90 % of lung cancer cell lines have a decrease in SASH1 mRNA levels (Zeller et al., 2003), however little characterisation of SASH1 function in lung cancer has been undertaken.
Methods:
We evaluated SASH1 expression in transformed normal and malignant non-small cell lung cancer cell lines. We also utilised cell based assays to study the effects of altered SASH1 levels on cell survival and proliferation. Identification of a novel SASH1 targeting drug was performed through connectivity mapping.
Results:
SASH1 protein expression was down regulated in two of the five lung cancer cell lines compared to immortalized normal bronchial epithelial cells. Prognoscan assessment identified decreased SASH1 mRNA expression reduced patient survival. The depletion of SASH1 in lung cells resulted in a significant increase in cellular proliferation in cancer lung cells. Connectivity mapping predicted the drug Chloropyramine would lead to an increase in SASH1 expression. We demonstrated that Chloropyramine upregulates SASH1 in malignant cell lines. In keeping with this we have demonstrated the Chloropyramine inhibited lung cancer proliferation in vitro. We also explored the role of SASH1 in apoptosis. Following ultraviolet light exposure SASH1 is cleaved by Caspase-3. The C-terminal fragment of SASH1 then translocates from the cytoplasm to the nucleus where it associates with chromatin. The overexpression of wild type SASH1 or cleaved SASH1 amino acids 231-1247 leads to an increase in apoptosis, however loss of the SASH1 cleavage site and/or nuclear translocation prevents this initiation of apoptosis. Mechanistically SASH1 cleavage is required for the translocation of the transcription factor NF-κB to the nucleus. The use of the NF-κB inhibitor DHMEQ demonstrated that the effect of SASH1 on apoptosis was dependent on NF-κB, indicating a co-dependence between SASH1 and NF-κB for this process.
Conclusion:
We have shown that SASH1 contributes to apoptosis via a NF-κB-dependent mechanism. Agents that upregulate SASH1, such as chloropyramine or SASH1 gene therapy, are potential novel approaches to the management of NSCLC in the future.
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P3.03 - Poster Session with Presenters Present (ID 473)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Mesothelioma/Thymic Malignancies/Esophageal Cancer/Other Thoracic Malignancies
- Presentations: 1
- Moderators:
- Coordinates: 12/07/2016, 14:30 - 15:45, Hall B (Poster Area)
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P3.03-021 - When RON MET TAM in Mesothelioma: All Druggable for One, and One Drug for All? (ID 5025)
14:30 - 14:30 | Author(s): M.P. Barr
- Abstract
Background:
Malignant pleural mesothelioma (MPM) is an aggressive inflammatory cancer associated with exposure to asbestos. Untreated, MPM has a median survival time of 6 months, and most patients die within 24 months of diagnosis. Therefore an urgent need exists to identify new therapies for treating MPM patients. The potential for therapeutically targeting receptor tyrosine kinase (RTK) signalling networks is emerging as a critical mechanism in ‘oncogene addicted’ cancer, with RTK inhibitors evolving as areas of considerable importance in cancer therapy. Furthermore, RTK hetero-dimerization has emerged as a key element in the development of resistance to cancer therapy. As such TKIs which target several RTKs may have superior efficacy compared with TKIs targeting individual RTKs. We and others have identified c-MET, RON, Axl and Tyro3 as RTKs frequently overexpressed and activated in MPM, making these attractive candidate therapeutic targets. A number of orally bioavailable small molecule inhibitors have been developed which can target these receptors. LCRF0004 specifically targets RON, whereas ASLAN002 (BMS-777607) or Merestinib (LY2801653) are orally bioavailable small molecule inhibitors which inhibit c-MET, RON, Axl and Tyro3 at nanomolar concentrations. These drugs may therefore have applicability in the treatment/management of MPM.
Methods:
A panel of MPM and normal pleural cell lines were screened for expression of Tyro3, c-MET, RON and Axl by RT-PCR, and subsequently examined in a cohort of patient samples comprising benign, epithelial, biphasic, and sarcomatoid histologies by qPCR. The effects of two small molecule inhibitors LCRF0004, ASLAN002 on MPM cellular health were assessed in vitro. The effects of LCRF0004 and ASLAN002 were subsequently examined in an in vivo SQ xenograft tumour model.
Results:
Expression of various RON isoforms, c-MET, Tyro3 and Axl were observed in all cell lines. Significantly higher expression of all genes were found in the malignant tumour material versus benign pleura and this was validated in other datasets. Both LCRF0004 and ASLAN002 demonstrated significant anti-tumour efficacy in vitro. In xenograft models ASLAN002 was far superior to LCRF0004.
Conclusion:
Our results suggest that a multi-TKI, targeting the RON/MET/TAM signalling pathways, may be a more effective therapeutic strategy for the treatment of MPM as opposed to targeting RON alone.
