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J. Sage
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MINI 27 - Biology and Other Issues in SCLC (ID 152)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Small Cell Lung Cancer
- Presentations: 15
- Moderators:P.A. Bunn, Jr, J. Sage
- Coordinates: 9/09/2015, 16:45 - 18:15, 605+607
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MINI27.01 - Investigation of Chimeric Antigen Receptor T Cells as a Novel Immunotherapy for SCLC (ID 2901)
16:45 - 16:50 | Author(s): W.L. Denning, D. Crossland, K.A. Gold, S. Ang, S. Olivares, N. Belousova, B. Glisson, L. Cooper, J.V. Heymach
- Abstract
- Presentation
Background:
Small cell lung cancer (SCLC) is an aggressive malignancy with an average of 20,000 new cases per year and 16,000 deaths per year. SCLC accounts for about 10-15% of newly diagnosed lung cancers. Even in the face of extensive research, the standard of care- platinum-based combination chemotherapy- has not changed in decades. Yet even with modern chemotherapy formulations, the two year survival rate for advanced disease stages is less than 5%. Complicating treatment is that often at the time of diagnosis, SCLC as already metastasized to the patient’s surrounding lymph nodes. Therefore, a novel therapeutic strategy will have address three disease aspects: (1) reduce primary tumor growth and eliminate metastatic spread; (2) avoid resistance mechanisms used by SCLC to escape radio- and chemotherapies; (3) synergize with or supersede current therapeutic strategies. Chimeric antigen receptor T cells, little explored in SCLC, is well suited to address these aspects.
Methods:
Human SCLC cell lines were analyzed using a 90 gene signature to establish immunological targets. Western blot analysis confirmed the expression of CD56 and other targets on SCLC cell lines. For CAR T cell generation, PBMC were electroporated with the Sleeping Beauty transposase and a transposon containing a CD56R chimeric antigen receptor. CD56R-CAR transduced T cells were cultured for 4 weeks in the presence of K562 cells expressing CD56 and the cytokines IL-2/IL-21 to expand CD56R-CAR T cells. CAR T cells were tested in vitro for killing ability in the presence of three SCLC cell lines using a chromium release assay. CAR T cells were also analysed via FACS to assess CAR expression, T cell phenotype, and memory status.
Results:
An analysis of immune markers in SCLC cell lines revealed that, compared to NSCLC lines, there is a reduction in the expression of suppressive ligands and co-stimulatory ligands, antigen presentation, and natural killer ligands. SCLC cell lines, however, express high levels of CD56. When two CD56-positive and one CD56-negative cell line was tested, CD56-CAR T cells could kill efficiency CD56 expressing cell lines, however there was little killing of the CD56-negative cell line. An analysis of PBMCs cultured after electroporation revealed that a large percentage of CD3+ T cells expressed the CD56 CAR and even after 4 weeks in culture, the CAR T cells displayed a memory phenotype.
Conclusion:
An interrogation of SCLC cell lines versus NSCLC cell lines revealed that SCLC cell lines had reduced expression of checkpoint ligands, NK cell killing ligands, antigen presentation, but consistent with their origin, high expression of CD56. Our conclusion from this analysis is that expansion of SCLC-specific immune responses in vivo or elicitation of de novo responses in vivo will be hindered. Therefore, immunotherapies centered around adoptive transfer of T cell that can kill in an HLA-independent manner maybe better suited for SCLC. In that vein, CD56R-CAR T cells effectively targeted CD56-positive SCLC in vitro, but was unable to kill CD56-negative cells- which indicates a possible escape variant. Our lab is now moving toward testing CD56R-CAR T cell in vivo in both xenograph models and spontaneous ones.
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MINI27.02 - RPS25 Is Essential for the Translation of the Seneca Valley Virus Genome and Proliferative Capacity of Small Cell Lung Cancer Cell Lines (ID 3278)
16:50 - 16:55 | Author(s): L.A. Miles, T. Hitchman, J. Poirier, C.M. Rudin
- Abstract
- Presentation
Background:
Small cell lung cancer (SCLC) is an extremely aggressive and lethal disease for which there is a desperate need for novel and more effective treatments. A recently discovered oncolytic picornavirus, Seneca Valley Virus (SVV), infects tumors with neuroendocrine features, including SCLC with high selectivity. SVV is highly effective in the eradication of solid tumors in multiple in vivo models; however the mechanism of selective tropism for SVV is unknown. Because of the strong selectivity of the virus for SCLC, we hypothesize the host determinants of SVV permissivity could constitute future druggable targets for the treatment of SCLC.
Methods:
A retroviral gene trap mutagenesis screen was utilized in HAP1, a haploid human cell line permissive to SVV, HAP1. Once mutagenized, resistant cells, or cells with retroviral insertion in a gene essential to the viral life cycle, were selected for by incubation of the pool with SVV at a high multiplicity of infection (MOI). Hits from this screen were deconvoluted using an insertion mapping approach. Illumina sequencing provided quantitative counts of each insertion site in each gene. Hits from the screen were validated using various mechanistic approaches.
Results:
Our screen identified multiple unique insertion sites in the gene RPS25 on Chromosome 11. The RPS25 protein is a ribosomal protein that is a component of the 40S subunit of the ribosome. RPS25 has been previously shown to be important for IRES-dependent translation of multiple viral genomes as well as cellular mRNAs containing IRES elements. Using the CRISPR-Cas9 approach, we knocked out the RPS25 gene in the SVV-permissive SCLC cell line, NCI-H446. Upon total knock-down of RPS25, H446 cells become completely resistant to cell killing by SVV at high MOI. Surprisingly, these cells also show a severely marked decrease in doubling time and robustness in culture. In contrast, RPS25 CRISPR knock-down in HEK293T cells has been previously shown to have no distinguishable phenotype other than defects in IRES-dependent translation. Further studies to fully characterize the interaction of RPS25 with the SVV genome as well as the importance of RPS25 in other SCLC cell lines are ongoing.
Conclusion:
We have identified a host protein that is essential for SVV replication and infection using a genome wide mutagenesis screen. SCLC cells completely defective in RPS25 are resistant to SVV-dependent cell killing. RPS25 appears to not only be important for the life cycle of SVV but may be important in proliferative capacity in SCLC. As SVV is highly selective for SCLC, we hypothesize that the host determinants of SVV tropism may be very specific to SCLC cells. Proteins important in the SVV life cycle may be novel “druggable” targets for the treatment of SCLC.
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MINI27.03 - PD-L1 Expression in Small Cell Lung Carcinoma: An Immunohistochemical Analysis of 26 Cases Using Two Anti-PD-L1 Antibodies (ID 2936)
16:55 - 17:00 | Author(s): P.B. Illei, P. Forde, C. Hann, S. Yang, R. Kelly
- Abstract
- Presentation
Background:
Small cell lung carcinoma (SCLC) represents 15% of lung cancers and is treated using chemotherapy +/- radiation but despite initial responses most recur within a few months and become resistant to therapy. Novel immune checkpoint inhibition of programmed death-1 (PD1) targeted therapy has shown promise in other solid tumors including non-small-cell lung cancer (NSCLC) and malignant melanoma. In some tumor types correlation with response and significant expression of programmed death- ligand 1 (PD-L1), the lead candidate biomarker of anti-PD-1 therapy, has been described but no data is available regarding expression levels in SCLC. Here we report the rate of PD-L1 expression in SCLC and in associated tumor infiltrating immune cells lymphocytes and macrophages.
Methods:
Immunohistochemistry (IHC) for PD-L1 using two monoclonal antibodies (clone 5H1 and clone SP142) and for CD3 (clone PS1) was performed on standard formalin fixed paraffin embedded tissue sections of 21 resected SCLC specimens (median age: 67) and three additional tumors with pre- and post-therapy biopsies. Since there is no generally accepted scoring system for PD-L1 expression we chose to evaluate staining in tumor cells and immune cells infiltrating the tumor nests and in adjacent stroma using a 4 tier semi quantitative scoring system (score 0 -no or <1%, 1+ 1-<5%, 2+ 5-25% and 3+ >25% of cells staining). Both cytoplasmic and membranous staining was accepted as positive. The number of tumor infiltrating lymphocytes (TIL) were estimated utilizing a CD3 stain while macrophages were identified on corresponding H&E stains.
Results:
PD-L1 staining of tumor cells and Immune Cells (TIL & Macrophage) are shown in the table below. Membranous PD-L1 staining was only seen in two tumors and in variable number of immune cells with 2+ or 3+ PD-L1 scores. The majority of positive staining was cytoplasmic with both antibodies. The staining intensity was stroger with the 5H1 antibody. The paired pre- and post-therapy samples were all negative for PD-L1.
* Tumors with membranous staining; IC: immune cellsClone/score PD-L1 staining in 5H1 Tumor IC in tumor IC in stroma 0 (<1%) 19/21 (90%) 7/21 (33%) 5/21 (24%) 1+ (1-<5%) 1/21 (5%)* 11/21 (53%) 6/21 (29%) 2+ (5-25%) 1/21 (5%)* 3/21 (14%) 7/21 (33%) 3+ (>25%) 3/21 (14%) SP142 Tumor IC in tumor IC in stroma 0 (<1%) 20/21 (95%) 8/21 (38%) 10/21 (48%) 1+ (1-<5%) 1/21 (5%)* 11/21 (52%) 7/21 (33%) 2+ (5-25%) 2/21 (10%) 4/21 (19%) 3+ (>25%)
Conclusion:
Most SCLC are tumor membrane PD-L1 negative by IHC. A subset of SCLC contain PD-L1 positive TILs and/or macrophages in the tumor and the stroma. No up regulation of PD-L1 expression was seen in a small pilot sample of matched pre- and post-therapy biopsies. It is unclear whether PD-L1 expression assessed by IHC will be a predictive marker for PD-1 targeted therapy in SCLC. Preliminary data indicates single agent and combined checkpoint inhibitors (PD1 plus CTLA-4 inhibitors) are active in previously treated SCLC indicating additional research is required to understand their mechanism of action in a tumor type that has seen no therapeutic advances in the last two decades.
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- Abstract
- Presentation
Background:
Blocking the interaction between the programmed cell death (PD)-1 protein and one of its ligands, PD-L1, has been reported to have impressive antitumor responses. PD-L1 interaction is a major pathway often hijacked by tumors to suppress immune control. Studies on the roles of PD-L1 in non-small cell lung cancer (NSCLC) are controversial, but its roles in small cell lung cancer (SCLC) are rare and unclear. Moreover, MET/HGF axis seems to be the other one of the most aberrant signaling pathways in SCLC. The aim of our study was to investigate the expression and prognostic roles of PD-L1 and cellular-mesenchymal to epithelial transition factor(c-MET) in SCLC.
Methods:
The expression of PD-L1 and c-MET were evaluated by immunohistochemical analysis in 83 specimens of SCLC, including 47 limited disease (LD) and 36 extensive disease(ED). Tumors with PD-L1 staining in over 5% of tumor cells were scored as positive for PD-L1 expression. Tumors with c-MET strong staining in at least 10% or weak to moderate staining in at least 40% of tumor cells were scored as positive for c-MET expression. Survival analysis was performed using the Kaplan-Meier method.
Results:
The positive rate of PD-L1 and c-MET in SCLC specimens were 51.8% and 25.3% respectively. The higher expression level of PD-L1 in tumor specimens was significantly correlated with a limited disease (LD) stage (p=0.004), a normal serum LDH level (p=0.031), and a normal NSE level (p=0.005). No association was found between the expression level of c-MET and PD-L1 , or c-MET expression with the other clinical characteristics of SCLC patients. SCLC patients with PD-L1-positive tumors showed significantly longer overall survival (OS) than those with PD-L1-negative (median OS, 17.0 vs 9.0, p=0.018). SCLC patients with positive c-MET expression showed a trend of shorter overall survival (12.0 vs 15.0, p=0.186). But sub-analysis of Limited disease (LD)-stage patients showed that the c-MET negative group had a longer OS (25.0 vs 14.0; p=0.011). Multivariate analyses revealed that LD stage, good performance status but except for PD-L1 or c-MET immunoreactivity were independently predictive of better OS.
Conclusion:
In patients with SCLC, expression of PD-L1 was positively correlated with a LD stage and better OS, but was not an independently predictive factor of outcome. High expression level of c-MET revealed a trend of worse outcome. It was associated with poor prognosis especially in LD-Stage patients.
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MINI27.05 - Discussant for MINI27.01, MINI27.02, MINI27.03, MINI27.04 (ID 3379)
17:05 - 17:15 | Author(s): J.W. Neal
- Abstract
- Presentation
Abstract not provided
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- Abstract
- Presentation
Background:
As a subtype of lung cancer, small cell lung cancer (SCLC) remains a severe threat to human health. Although it is initially a chemosensitive disease, development of acquired resistance is a major problem. Studies in recent years revealed that cancer stem cell (CSC) could play a role in this process. However, the CSC specific marker and the detailed signal pathway associated with acquired resistance in SCLC is unknown yet. It was recently reported that the voltage-dependent calcium channel α2δ1 subunit positive cells is a CSC marker in hepatic cell cancer and that 1B50-1 is the specific monoclonal antibody of the α2δ1 subunit. In present study, we attempted to disclose that α2δ1 could play a role in acquired resistance of SCLC. Also we investigated possible molecular mechanism of α2δ1 mediated resistance in SCLC and finally provided the potential strategies overcoming the resistance.
Methods:
We screened for positive expression of 1B50-1and CD133 in SCLC cell lines and in patient-derived xenograft (PDX) models, and we used flow cytometry to verify the properties of CSCs. We recorded the expression of 1B50-1 before and after chemotherapy in PDXs in chemosensitive and resistant models to determine if α2δ1 subunit-positive cells were related to acquired resistance. We used exome and transcriptome sequencing to explore the expression of genes related to stem cell properties and drug resistance. We used Western blotting to verify the key molecules and pathways in the process of drug resistance. On the basis of these results, we explored the mechanisms of acquired drug resistance that are mediated by the α2δ1 subunit.
Results:
We observed a difference in the positive expression levels of 1B50-1 and CD133 in SCLC cell lines (H1048, H69, and H209) and PDX models. Both 1B50-1-positive and CD133-positive cells exhibited stem cell-like properties such as the capacity to self-renew in vitro, tumorigenesis in vivo, the potential for differentiation, and high expression levels of genes related to CSCs and drug resistance. Chemotherapy could induce the enrichment of 1B50-1-positive cells but not CD133-positive cells in PDXs. Also, high rates of 1B50-1-positive cells corresponded to high levels of resistance. Together, these findings indicated that the expression of 1B50-1 is related to chemoresistance. Exome and transcriptome sequencing revealed that the expressions of multiple pathway related genes in pathways, including MAPK, CAMs, TGFβ, and Notch, were increased in 1B50-1-positive H1048 cells. Western blotting revealed the activation of the Erk protein in the MAPK pathway and the over-expression of the Erk protein in 1B50-1-positive H1048 cells. The specific α2δ1 antibody 1B50-1 improved response to chemotherapy and delayed relapse when combined with chemotherapy or used y as maintenance therapy.
Conclusion:
The α2δ1 subunit positive SCLC cells (1B50-1+) displayed CSC properties, and were associated with acquired resistance. The Erk protein in the MAPK pathway was highly expressed in the 1B50-1-positive H1048 cell line, and might be the key molecule involved in resistance mediated by the α2δ1 subunit. The α2δ1 subunit-specific antibody 1B50-1 could improve response to chemotherapy and delay relapse when combined with chemotherapy or when used as sequential therapy.
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MINI27.07 - Targeting Cancer Stem Cells in Small Cell Lung Cancer (ID 2727)
17:20 - 17:25 | Author(s): V. Kolev, Y. Wang, M. Padval, J. Pachter, D. Weaver
- Abstract
- Presentation
Background:
Small cell lung cancer (SCLC) is an extremely aggressive cancer with limited treatment options and poor outcome. The majority of SCLC patients respond to frontline chemotherapy, but experience rapid recurrence with metastasis, that may be attributed to the prevalence of cancer stem cells (CSCs). We previously demonstrated that PI3K/mTOR signaling is key for CSCs in cell culture and solid tumor models. As shown with a dual PI3K/mTOR inhibitor, VS-5584, inhibition of multiple PI3K isoforms and mTOR is necessary to achieve preferential targeting of CSCs.
Methods:
Antitumor activity of VS-5584 was assessed by in vitro proliferation assay as well as in multiple xenograft models in vivo, including patient-derived xenograft models. Anti-CSC activity was measured by the side-population CSC assay in vitro and in limiting dilution tumor initiation assay in vivo.
Results:
VS-5584 inhibited SCLC growth in vitro at sub-µM IC50, and was synergistic with cisplatin and etoposide in reducing the viability of SCLC cells. In vivo, single agent VS-5584 (20 mg/kg, 3 days per week dosing, MWF) demonstrated robust anti-CSC activity in the NCI-H841 SCLC model by reducing tumor initiating potential 70-fold (p=5x10[-6]). In tandem, VS-5584 partially reduced tumor growth of the NCI-H841 xenograft tumors. Furthermore, a VS-5584 dose dependency was evident, both for tumor initiating potential and tumor growth reduction. When VS-5584 was combined with cisplatin and etoposide, the standard of care agents for SCLC, an increased tumor growth inhibition was observed whether VS-5584 was concurrently administered or added sequentially following the dual chemotherapy. In the SCLC PDX model, combination treatment also suppressed the regrowth of the tumor following cessation of chemotherapy for extended duration. VS-5584 was found to preferentially induce apoptosis in CSCs in multiple cell lines, indicating that these cells are eliminated through cell death-related mechanism. Importantly, we demonstrated that for eradication of CSCs it is necessary to inhibit simultaneously multiple PI3K isoforms and mTOR pathways.
Conclusion:
The VS-5584 pre-clinical findings support the preferential targeting of CSCs in SCLC models and provide an important rationale for advancing clinical development of the compound. A phase 1 dose finding clinical trial is on-going to establish a Phase 2 dose of VS-5584 and explore target inhibition. VS-5584 alone or in combination with standard of care chemotherapy may lengthen the time to relapse and improve outcome for patients with small cell lung cancer.
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MINI27.08 - NOTCH3 Protein Expression and Outcome in Small Cell Lung Cancer (SCLC) and Therapeutic Targeting with Tarextumab (Anti-Notch 2/3) (ID 2999)
17:25 - 17:30 | Author(s): A. Chiang, J. McLaughlin, M.C. Pietanza, A. Spira, R. Jotte, S. Gadgeel, A. Mita, L. Gluck, S. Liu, A. Kapoun, D. Hill, R. Herbst, L. Zhou, J. Dupont, D.R. Spigel
- Abstract
- Presentation
Background:
NOTCH expression is associated with cancer cell survival via effects on cancer stem/progenitor cells. Targeting NOTCH2 and 3 decreases growth and survival of SCLC patient-derived human tumor xenografts (PDX). Phase1b/2 trials testing Tarextumab (TRXT) anti-NOTCH2/3 therapy are underway (NCT01647828 and NCT01859741) and show promising anti-tumor activity. Here, we studied NOTCH3 protein expression using immunohistochemistry (IHC) in SCLC human tissues and correlated with survival. Also, we studied NOTCH3 gene expression in phase 1b patients (pts) treated with TRXT.
Methods:
For NOTCH IHC staining, murine monoclonal antibodies were generated by immunizing mice with a NOTCH3 extracellular domain (ECD) protein, then creating hybridomas. Clones were screened by FACS and western blots for specificity to NOTCH3.ECD. A lead clone was selected for NOTCH3 protein measurement in 47 SCLC samples represented in a tissue microarray from Yale Pathology Tissue Services (YPTS). NOTCH3 signal was determined in tumors using H-scores generated by Leica Aperio Scanscope IHC membrane image analysis. For survival analysis, NOTCH3 signal was binarized with cutoffs defined by X-tile software. For the phase 1b clinical trial, a standard 3+3 dose escalation design was employed with cohorts of 3 to 6 pts treated at each dose level. TRXT was given IV on Day 1 of each 21 day cycle with etoposide 100 mg/m[2] (Days 1-3) and cisplatin 80 mg/m[2 ]or carboplatin at AUC 5 (Day 1) for 6 cycles, followed by TRXT alone every 21 days until progression of disease or unacceptable toxicities. Then, the MTD TRXT plus etoposide and carboplatin was confirmed in a cohort of 6 subjects. All pts are required to submit tissues for Notch 3 gene expression and IHC staining.
Results:
A single hybridoma clone demonstrating specific reproducible membranous staining with a dynamic range for NOTCH3.ECD in control and PDX tissues was chosen for IHC analysis in SCLC human FFPE tissues (n=47). Forty cases (85.1%) demonstrated NOTCH3 signal, with eighteen (38.3%) having none to very low signal. Of the 31 cases with adequate follow-up, there was a strong trend with worse outcome and high NOTCH3 expression in the extensive stage (p=0.063), but not in limited stage (p=0.857). The level of significance was a function of the experimental cut-point and can only be considered exploratory. Finally, 27 pts were treated with TRXT in the phase 1b trial, with an overall response rate of 84%. The median duration of treatment was 128 days (6 cycles) with mPFS and mOS of 124 and 228 days, respectively. The median follow-up for PFS and OS was 86 and 107 days, respectively. Twenty-five pts have tissues evaluable for NOTCH3 gene expression and the analysis is underway.
Conclusion:
NOTCH3 IHC staining showed expression in most SCLC cases, with high NOTCH3 trending towards worse survival in extensive stage. This supports the rationale of targeting NOTCH3 by TXRT in SCLC pts. Further evaluation of the prognostic and predictive value of TRXT for anti-Notch therapies in SCLC is underway in an ongoing Phase 2 clinical trial.
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MINI27.09 - A DLL3-Targeted ADC Effectively Targets Pulmonary Neuroendocrine Tumor-Initiating Cells to Result in Sustained Tumor Regressions (ID 2533)
17:30 - 17:35 | Author(s): L.R. Saunders, A.J. Bankovich, W.A. Anderson, M. Aujay, S. Bheddah, K.A. Black, R. Desai, P. Escarpe, J. Hampl, A. Park, A. Laysang, D. Liu, J. Lopez-Molina, M. Milton, M. Pysz, H. Shao, M. Torgov, S. Williams, O. Foord, P. Howard, J.T. Poirier, M.C. Pietanza, P.P. Massion, C.M. Rudin, R.A. Stull, B.S. Slingerland, S.J. Dylla
- Abstract
- Presentation
Background:
Pulmonary neuroendocrine tumors such as small cell lung cancer (SCLC) and large cell neuroendocrine cancer (LCNEC) remain among the most deadly malignancies and are increasing in incidence. Patient-derived xenograft (PDX) tumors provide excellent models to study tumor biology and discover tumor-initiating cell (TIC) populations. Novel therapies that target and eradicate TIC represent a promising strategy to improve survival. An effectively targeted antibody-drug conjugate (ADC) carrying a cell-cycle independent toxin should result in significant anti-tumor activity and eliminate TIC.
Methods:
Whole transcriptome sequencing was performed using TIC isolated by fluorescence-activated cell sorting from SCLC and LCNEC PDX tumors. Quantitative RT-PCR, microarray analysis of PDX tumors and cell lines, and mining of publically available transcriptome and proteome datasets were executed to validate that prospective targets, such as Delta-like protein 3 (DLL3), were highly expressed in neuroendocrine tumors, but limited in their expression in normal tissues. DLL3-specific monoclonal antibodies were generated and used to determine protein expression by immunohistochemistry, flow cytometry and ELISA. Select DLL3-specific antibodies were conjugated to a cell-cycle independent pyrrolobenzodiazepine (PBD) dimer toxin and evaluated for their ability to internalize and mediate cell killing. Finally, established SCLC and LCNEC PDX tumors were treated in vivo with a lead anti-DLL3 ADC (i.e. SC16LD6.5). Limiting dilution assay (LDA) serial transplantation experiments were executed to assess the impact of SC16LD6.5 on TIC.
Results:
Elevated expression of DLL3 mRNA was discovered in TIC of SCLC and LCNEC PDX tumors and confirmed in additional distinct primary SCLC and LCNEC tumor samples and PDX tumors. In contrast, little to no mRNA expression was detected in vital organs and other normal tissues outside of the brain. DLL3-specific antibodies confirmed protein expression on the cell surface in both primary SCLC and LCNEC tumors and in PDX tumors initiated from patients with these diseases, whereas protein was scarce in normal tissues. SC16LD6.5 rapidly internalizes and localizes to late endosomes, and treatment of 10 SCLC and 2 LCNEC PDX tumor models resulted in significant and durable tumor regression with a median time to progression benefit of 75 days versus 16 days with standard-of-care (SOC: SCLC, cisplatin/etoposide; LCNEC, cisplatin). During the course of these in vivo studies, many mice were cured as tumors often did not recur despite being followed for 120+ days post-randomization and treatment. LDA experiments executed using tumors actively responding to SC16LD6.5 provided further functional evidence that the common lack of tumor recurrence following treatment resulted from effective targeting of DLL3-expressing TIC. In vivo efficacy strongly correlated with DLL3 protein expression, and responses were observed in PDX tumor models initiated from patients with both limited and extensive stage disease and independent of their sensitivity to SOC.
Conclusion:
The DLL3-targeted ADC, SC16LD6.5, effectively targets and eradicates TIC in SCLC and LCNEC PDX tumors. SC16LD6.5 (i.e. rovalpituzumab teserine) is currently concluding Phase 1b trials and is a promising first-in-class therapeutic for the treatment of high grade pulmonary neuroendocrine tumors.
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MINI27.10 - Discussant for MINI27.06, MINI27.07, MINI27.08, MINI27.09 (ID 3380)
17:35 - 17:45 | Author(s): D.L. Gibbons
- Abstract
- Presentation
Abstract not provided
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MINI27.11 - Comprehensive Mutation Analysis of Never-Smokers with Small Cell Lung Cancer (SCLC) (ID 3135)
17:45 - 17:50 | Author(s): M.C. Pietanza, H. Won, L.M. Krug, A.M. Varghese, G.J. Riely, N. Rekhtman, L. Wang, W.D. Travis, M. Zakowski, M. Ladanyi, M. Berger, M.G. Kris, C.M. Rudin
- Abstract
- Presentation
Background:
Although most patients with SCLC are current or former smokers, this disease has been reported in never-smokers. In our prospective genomic profiling of SCLC patients, we have identified four never-smokers. Here, we report next generation sequencing (NGS) results for these four SCLC patients and describe how they differ from those of smokers.
Methods:
We are evaluating pathologically confirmed SCLC tumors in patients undergoing treatment. Formalin-fixed, paraffin-embedded surgical resections, core biopsies, and fine needle aspirates are being evaluated using a targeted, hybrid capture-based, NGS assay, MSK-IMPACT, which identifies single nucleotide variants, indels, and copy number alterations in 341 cancer-associated genes. We determined never-smoking status prospectively: all smoked <100 cigarettes in their lifetime. Clinical data on stage [extensive (ES), limited (LS)], treatment, and response were collected.
Results:
Four never-smokers have been identified within the 50 patient samples that have undergone NGS evaluation thus far. The median age at diagnosis of the four never-smokers is 58 (range, 47-75); 50% are male; and one presented with LS-SCLC. None of these four patients developed SCLC as acquired resistance to EGFR tyrosine kinase inhibitors after treatment for EGFR-mutant lung cancers. The tumors from the four never-smokers displayed a median of 3 non-synonymous somatic mutations, while those from moderate (<20 pack years) and heavy (20+ pack years) smokers contained 4.5 and 8 mutations, respectively (P<0.05). None of the four never-smoker samples contained smoking associated G-to-T transversions (see Table). Inactivation of RB1 and TP53 occurred in 75% and 50% of the samples, respectively. Only patient 4 had platinum-refractory disease. The median survival of these patients was 20.7 months (range, 17 to 25).Sample Gene altered Alteration Present Protein Alteration Base Pair Alteration Patient 1 PHOX2B Missense Mutation P82L G-to-A NOTCH1 Frame-Shift Insertion P2485fs RB1 Splice Site R500_splice G-to-A TP53 Frame-Shift Deletion V218fs TP53 Frame-Shift Deletion V73fs TERT Amplification Patient 2 CBL Missense Mutation C401S G-to-C GNAS Missense Mutation M102V A-to-G MYCL Amplification Patient 3 TP53 Nonsense Mutation R342 G-to-A RB1 Frame-Shift Insertion T197fs CDKN2C Amplification MYCL Amplification Patient 4 RB1 Nonsense Mutation C666 ETV1 Amplification
Conclusion:
Using a targeted NGS assay, we have shown that the molecular characteristics differ between never-smokers and smokers, while the majority of the tumors demonstrate RB loss. Whole exome sequencing of the tumors from these never-smokers is underway. Ongoing comprehensive, multiplexed genotyping is needed to fully characterize the molecular diversity of SCLC in this unique population.
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MINI27.12 - Using a Cell Surface Antibody Screen to Identify Biomarkers of Drug Resistance in Small Cell Lung Cancer (SCLC) (ID 3002)
17:50 - 17:55 | Author(s): D. Meyers, A. Poeppl, V. Bhat, C. Peltier, A. Raouf, S. Banerji
- Abstract
- Presentation
Background:
SCLC is an aggressive malignancy that shows dramatic clinical responses in 70% of cases to platinum-based chemotherapy in the first line setting, while the remainder have de novo treatment resistance. Of initial treatment responders, almost all will relapse with drug-resistant disease within months of initial therapy. From a clinical perspective, the emergence of drug resistance remains one of the most important barriers to improving SCLC patient outcomes. Better models of in vitro and in vivo drug resistance are therefore required. Cell surface markers are proteins expressed on the outer surface of cells that can identify specific cell types and biologic states. Surface markers represent an attractive class of biomarkers in SCLC: 1) they are independent of cellular transport mechanisms that are known to play a role in SCLC drug resistance; and 2) they can be readily accessed for diagnostic and therapeutic purposes using commercial antibodies.
Methods:
NCI-H69 is a classic SCLC cell line derived from a patient prior to systemic treatment, and is chemotherapy sensitive. H69AR is an anthracycline-resistant derivative cell line generated through serial culture of NCI-H69 in increasing concentrations of Adriamycin. H69AR is also cross-resistant to other cytotoxic drugs commonly used to treat SCLC. We performed a pilot screen in both cell lines in duplicate using a human cell surface marker panel containing Alexa Fluor 647-conjugated antibodies against 242 unique cell surface proteins. High-throughput multiplexed flow-cytometry was performed to generate cell surface expression profiles for each antibody in each cell line.
Results:
A total of 53 markers were expressed in at least 20% of cells in either cell line, with 22 positive markers shared by both cell lines including CD44. NCI-H69 was uniquely positive for 24 markers including CD56, a neural progenitor marker used commonly to diagnose SCLC. Seven markers were uniquely positive in H69AR including CD9 and some of its known interactors. The percentage H69AR cells positive for each of the 7 markers ranged from 25% to 88%. CD9 is a member of the transmembrane 4 superfamily involved in many cellular processes including differentiation, adhesion, and signal transduction. Eighty-eight percent of H69AR cells were positive for CD9 compared to only 5.4% of H69 cells. CD9 has previously been implicated in a cell adhesion-mediated drug resistance mechanism in unrelated SCLC chemotherapy-resistant cell lines (S. Kohmo et al. Cancer Research 2010).
Conclusion:
Our pilot data provides a proof-of-concept for our surface biomarker screen-based approach to further understand mechanisms of chemotherapy-resistance in SCLC. We have expanded this screen to additional drug-sensitive and drug-resistant SCLC cell line pairs. Results of the expanded screen will be presented at the meeting.
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MINI27.13 - Progastrin-Releasing Peptide (ProGRP) as a Biomarker for Clinical Response in Small-Cell Lung Carcinoma (SCLC) (ID 1390)
17:55 - 18:00 | Author(s): T. Muley, X. Zhang, S. Holdenrieder, C.M. Korse, X. Zhi, R. Molina, Z. Liu, G. Hartmann, M. Van Den Heuvel, K. Qian, R. Marrades, C. Engel, B. Wehnl, F. Dayyani, F. Herth
- Abstract
Background:
Most cases of small-cell lung cancer (SCLC) are detected at extensive stage, where current guidelines recommend 4-6 cycles of chemotherapy. Although upfront progression to doublet platinum based chemotherapy in SCLC is <20%, current clinical practice often includes treatment monitoring with imaging, mainly with computed tomography, every two cycles. Since the purpose of imaging during treatment is identification of progression (to avoid further exposure to an ineffective but still potentially toxic regimen), we sought to evaluate whether monitoring SCLC patients during treatment with a blood-based biomarker (ProGRP) would correlate with response.
Methods:
Patients with SCLC treated with mainly standard chemotherapy at six centers worldwide (Europe and China) were included. ProGRP levels from serum or plasma were measured with a fully automated ProGRP assay in a prospective fashion prior to treatment start and repeatedly during treatment. Imaging was done and interpreted according to local guidelines at each institution. Percent change of ProGRP from baseline to the time of maximum response (‘best response’) was correlated with imaging findings, and patients were divided into two groups: Responders (= stable disease [SD] or better) vs. Non-Responders (= progression on scan). The ability of ProGRP to discriminate between Responders and Non-Responders was assessed by sensitivity and specificity.
Results:
215 patients with available CT result were included, of whom 145 had received first-line treatment (131 received platinum+VP-16 doublet). Clinical characteristics were as follows: 60.5% male, median age was 62 years, 72.1% were (ex)smokers, 93.5% with Stage IIIB or IV SCLC, and the majority of patients were either Caucasian (59.6%) or Asian (32.6%). Across all lines of treatment, 186/215 (86.5%) had SD or better as best response to treatment. There was a positive trend for higher ProGRP levels with clinical stage at presentation, and in general higher pre-treatment levels in 1[st] line compared to later lines of treatment. A decline in ProGRP levels was strongly correlated with response, whereby higher baseline levels were associated with subsequent higher relative declines of ProGRP during treatment. Using different cut-off levels for ProGRP decline during treatment (-50%, -70%, or -90%), we detected patients with no response to treatment based on ProGRP levels alone, with a sensitivity of 82.8%, 89.7% and 96.6%, and a specificity of 65.6%, 55.4%, and 39.8%, respectively. Specificity was increased by approximately 10% when only patients with baseline ProGRP levels exceeding 100 pg/ml were included.
Conclusion:
To our knowledge, this is the largest SCLC cohort to date with available ProGRP data for therapy monitoring. The data showed that ProGRP levels at baseline were positively correlated with advanced disease stage, and decline in ProGRP levels during treatment was associated with tumor control in SCLC. The ProGRP assay used in this study is currently not cleared or approved for use in the USA.
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MINI27.14 - The Aurora Kinase B Inhibitor AZD1152-HQPA Inhibitor in Small Cell Lung Cancer (SCLC) (ID 2161)
18:00 - 18:05 | Author(s): B. Helfrich, J. Kim, D. Gao, D. Chan, A. Tan, P.A. Bunn, Jr
- Abstract
- Presentation
Background:
Aurora kinase expression has been associated with a poor prognosis in non-small cell lung cancer (NSCLC) and aurora kinase inhibitors have activity in preclinical lung models. Aurora kinases are required for mitosis and cell division. Small cell lung cancer cells have rapid proliferation and higher rates of MYC family amplification, which makes aurora kinase inhibition a natural target.
Methods:
23-SCLC lines with known MYC family amplification and MYC family gene expression were exposed to varying concentrations of the specific aurora kinase B inhibitor AZD1152-HQPA. The percentage growth inhibition compared to control was determined in MTS assays at 120 hours. Cell lines were classified as “sensitive” if the GI50 concentration was < 50 nM and with ≥ 80% growth inhibition at 100 nM. Fisher’s exact test was used to determine the correlation between amplification of MYC family members and sensitivity of the cell lines to growth inhibition by AZD1152-HQPA. A two-group t-test (gene expression as a continuous variable) and an odds ratio estimate (dichotomized gene expression level) were used to determine a correlation between MYC family gene expression and growth inhibition by AZD1152-HQPA. To determine whether growth inhibition correlated with the published MYC-signature gene expression, we used Fisher’s exact test. In vivo growth inhibition by AZD1152 (prodrug) was evaluated on SCLC xenografts in nude mice.
Results:
Nine (39%) of the 23 cell lines were sensitive to AZD1152-HQPA with IC50 values < 50 nM. There was a significant association between sensitivity to growth inhibition by AZD1152-HQPA and cMYC amplification (p = 0.018). The odds of being sensitive is 16 (95% CI, 1.4, 183) times higher for cMYC amplified compared to non-cMYC amplified cell lines. By a two-group t-test, the mean cMYC gene expression of 10.9 (std 4) in sensitive lines compared to 7.2 (std 3.3) in resistant lines was also significant (p = 0.026). Cell lines were separated into two groups based on cMYC gene expression > 12.9 vs < 12.9. The odds of being sensitive is 11 (95% CI, 1.2, 103) time higher for cell lines with cMYC gene expression > 12.9 compared to cell lines with cMYC gene expression < 12.9. Sensitive cell lines were enriched in a published MYC-signature of gene expression (p = 0.042). AZD1152 (prodrug) caused significant growth delay in vivo in two of these lines. The doses of AZD1152-HQPA used in this study are within the range reported to be clinically achievable.
Conclusion:
Aurora kinase inhibitors have promise in SCLC therapy. Questions that currently need answering in translating aurora kinase inhibitors in the clinical setting are: (1) the dosing schedule to avoid myelosupression, (2) should aurora kinase inhibitors be used in maintenance therapy and (3) should the aurora kinase inhibitors be evaluating in combination with chemotherapy.
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MINI27.15 - Discussant for MINI27.11, MINI27.12, MINI27.13, MINI27.14 (ID 3381)
18:05 - 18:15 | Author(s): M. Peifer
- Abstract
- Presentation
Abstract not provided
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ORAL 07 - Lung Cancer Pathogenesis (ID 91)
- Event: WCLC 2015
- Type: Oral Session
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 8
- Moderators:J. Sage, E. Brambilla
- Coordinates: 9/07/2015, 10:45 - 12:15, 102+104+106
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ORAL07.01 - Evaluation of Epigenetic Mechanisms of Pluripotency in Human Respiratory Epithelia (ID 3041)
10:45 - 10:56 | Author(s): V. Shukla, M. Rao, J. Beers, H. Zhang, D. Wangsa, D. Wangsa, E. Reardon, J.A. Hong, M. Zhang, S. Davis, G. Chen, T. Ried, M.M. Miettinen, D.S. Schrump
- Abstract
- Presentation
Background:
Smoking is the number one risk factor for lung cancer worldwide. Recent data indicate that stem cells situated throughout the small airway epithelium may initiate cancer formation following direct exposure to inhaled carcinogens. In the present study we sought to generate induced pluripotent stem cells (iPSCs) from normal human small airway epithelial cells (SAECs) in order to investigate epigenetic mechanisms contributing to the cancer stem cell initiation process, and possibly identify novel targets for lung cancer therapy.
Methods:
Several different stocks of SAEC were transduced with Stemcca virus containing OKSM (Yamanaka factors); multiple randomly selected clones were expanded for further analysis. Spectral karyotyping was performed to confirm the purity of pluripotent cells. iPSC cells were injected in SCID mice to study teratoma formation. RNA and DNA were extracted from iPSC and parental SAEC for qRT-PCR and RNA-Seq analyses, as well as pyrosequencing of LINE-1, NBL2 and D4Z4 DNA repetitive elements, and promoter regions of several differentially regulated genes.
Results:
SAEC were reprogrammed to a pluripotent state. Generated iPSCs demonstrated hallmarks of pluripotency including morphology, proliferation, expression of surface antigens, stemness gene expression, and in vivo teratoma formation. Interestingly, no chromosomal aberrations were observed in iPSCs. Pyrosequencing did not demonstrate any significant changes in LINE-1, NBL2 and D4Z4 DNA methylation levels in iPSC compared to parental SAEC, suggesting relatively limited global hypomethylation following reprogramming. Consistent with these observations, cancer-testis genes such as NY-ESO-1, MAGE-A1 and MAGE-A3, which are frequently upregulated by DNA demethylation in lung cancer cells, remained transcriptionally repressed in the iPSC. On the other hand, NANOG and POU5F1 genes were hypomethylated in iPSCs relative to SAEC, correlating with their over-expression in iPSCs. RNA-Seq analysis revealed up-regulation of genes encoding components of Polycomb-Repressive Complex 2 (PRC2), and down-regulation of several tumor suppressor genes such as DKK1, p16 and p21 in iPSC relative to parental SAEC. Several novel pluripotency associated genes were also noted to be up-regulated in pulmonary iPSC, which are the focus of ongoing mechanistic studies.
Conclusion:
This is the first report demonstrating successful reprogramming of human respiratory epithelia to pluripotency. This model may prove useful for elucidating fundamental epigenomic mechanisms of pulmonary carcinogenesis and identification of novel targets for lung cancer therapy.
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ORAL07.02 - Metabolic Reprogramming in the Airway Epithelium of Individuals at High Risk for Lung Cancer (ID 2493)
10:56 - 11:07 | Author(s): S.M.J. Rahman, X. Ji, L.Z. Zimmerman, M. Li, B.K. Harris, M.D. Hoeksema, Y. Zou, J. Qian, R. Slebos, Y. Shyr, A. Spira, J.D. Young, D.C. Liebler, P.P. Massion
- Abstract
- Presentation
Background:
What defines the high risk airway epithelium for lung cancer remains a major challenge. Airway epithelium is prone to assault by the risk factors and considered to be the primary cell type involved in the field cancerization. Transcriptomic aberrations in the airway epithelium of individuals at risk for lung cancer have been reported earlier. However, very limited information exists about proteomic alterations in the airway epithelium. We investigated the molecular underpinnings of risk from proteomic alterations in the cytologically normal airway epithelium from individuals at risk for developing lung cancer.
Methods:
Bronchial brushings specimens were collected from individuals categorized as low, medium and high risk groups based on Bach risk model. Shotgun proteomic profiling data were acquired by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Proteins were identified using a combination of database search tools and candidate proteins were selected based on Jonckheere-Terpstra trend analysis. Pathway analysis was performed using WebGestalt. In vitro model of human bronchial epithelial cell line treated with cigarette smoke condensate (CSC) was used for metabolic flux experiments by gas chromatography mass spectrometry (GC MS) analyses.
Results:
We identified 2901 proteins in bronchial epithelial cells from risk stratified individuals. Jonckheere-Terpstra trend test resulted significantly altered expression of 315 proteins (trend p <0.05) with 238 up and 77 down trends. KEGG pathway analysis with the 315 proteins revealed very early events of possible metabolic reprogramming in the cytologically normal bronchial epithelium of individuals at high risk for lung cancer development. Fourteen enzymes of the glycolytic pathway, TCA cycle, pentose phosphate pathway, and glycogenolysis were over expressed. Six of these fourteen enzymes, PYGB, PFKP, PFKL, PKM2, IDH1, and IDH2 were rate limiting enzymes. In in vitro culture of human bronchial epithelial cells treated with CSC, lactate production and glucose consumption were increased suggesting Warburg effect and metabolic reprogramming. Evidence of glutamine metabolism through reductive carboxylation in CSC treated cells was obtained from the metabolic flux analyses of cells from this in vitro model. Contribution of labeled carbon from [U-[13]C5]-glutamine to TCA cycle in CSC treated cells were more than untreated control cells and there was strong M+5 citrate labeling in CSC-treated cells.
Conclusion:
Shotgun proteomic analysis of cytologically normal bronchial epithelial cells in individuals at increasing risk for lung cancer revealed over expression of carbohydrate metabolic enzymes in high risk individuals suggesting possible metabolic reprogramming. The altered profile of metabolic enzymes may provide a signature of lung cancer risk assessment and serve as the basis of patient selection for surveillance programs and chemoprevention.
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ORAL07.03 - MMP12 and LMO7 Are Key Genes Involved in the Early Pathogenesis of Squamous Cell Carcinoma of the Lung (ID 1173)
11:07 - 11:18 | Author(s): V.H. Teixeira, S. Lourenco, B. Carrol, M. Falzon, A. Capitanio, J. Brown, J.P. George, S.M. Janes
- Abstract
Background:
Lung cancer is the most lethal cancer type worldwide. In order to increase patient survival it is important to improve our understanding of the early changes associated with lung cancer progression. The progression of lung squamous cell carcinoma (SqCC) from pre-invasive lesions involves a series of histological changes which includes squamous metaplasia, mild, moderate and severe dysplasia, and carcinoma in situ (CIS). In these pre-invasive lesions the basement membrane is intact and there is no possibility of metastatic spread, which is in contrast to SqCC where there is the potential for metastasis as soon as invasion occurs. Our laboratory has a unique cohort of patients with pre-invasive lung SqCC lesions. Within this cohort there is a discrepancy between the prevalence of pre-invasive lesions and the incidence of invasive lung cancer, which suggests that not all pre-invasive lesions progress to invasive carcinomas. This tissue collection forms an internationally unique resource of lesions and will shed light on the molecular characteristics of lesions that progress compared to those that either regress or remain stable. The aim of this study was to identify and characterize key genes involved in the early pathogenesis of lung SqCC.
Methods:
Following histological review by two histopathologists to confirm that pre-malignant tissue is present in the biopsy specimens, the epithelial component of interest was laser-capture micro-dissected. This is vital in order to eliminate any cross-contamination from unwanted cells and to ensure that pre-invasive CIS specific gene expression profiles are generated. We have performed genome-wide gene expression Illumina’s Whole-Genome DASL® arrays in 20 progressive and 19 regressive pre-invasive lung SqCC lesions. The protein expression of Matrix metallopeptidase 12 (MMP12) and LIM domain 7 (LMO7) was also determined in the 39 pre-invasive lung cancer lesions by immunostaining analysis. The functional role of MMP12 and LMO7 in cell migration and invasion was demonstrated by MMP12 and LMO7-shRNA knockdown in different squamous cell carcinoma cell lines and human bronchial epithelial cells (HBECs), respectively.
Results:
We found 939 genes significantly differently expressed between the progressive and the regressive pre-invasive lung SqCC lesions. We identified a remarkably elevated expression of a spectrum of genes in the progressive lung SqCC lesions involved in different related cancer pathways including chromosome instability, p53 signalling and Wnt/β-catenin signalling. MMP12 and LMO7 were found within the highest significantly differently expressed genes and were therefore chosen to pursue studies focused on understanding the potential mechanisms leading to the development of lung SqCC. In agreement with the gene expression data the expression of MMP12 and LMO7 proteins were up-regulated and down-regulated, respectively, in progressive when compared with regressive lesions. Inhibiting MMP12 by MMP12 knockdown significantly reduced the migration and invasion of different squamous cell carcinoma cell lines (A431, H357 and H376). We also established HBECs knockdown targeting LMO7. We observed a significant increase in the migration and invasion of HBECs cells in the LMO7 shRNA knockdown compared to control.
Conclusion:
Our results suggest that MMP12 and LMO7 may be potential therapeutic markers for lung cancer at early stage.
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ORAL07.04 - Discussant for ORAL07.01, ORAL07.02, ORAL07.03 (ID 3304)
11:18 - 11:28 | Author(s): M.B. Beasley
- Abstract
- Presentation
Abstract not provided
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ORAL07.05 - Differential Tumorigenic Properties of Mesenchymal Cells From Neoplastic and Non-Neoplastic Human Lung in NSCLC (ID 1006)
11:28 - 11:39 | Author(s): D. Madeddu, A. Falco, L. Ampollini, C. Lagrasta, C. Frati, A. Gervasi, B. Lorusso, F. Saccani, G. Graiani, R. Alfieri, P. Petronini, P. Carbognani, L. Gnetti, P. Rossetti, G. Bocchialini, F. Ricci, E. Quaini, K. Urbanek, F. Quaini
- Abstract
- Presentation
Background:
Cancer Initiating Cells (CICs) and their niches may open new avenues in the pathogenesis and management of lung cancer. A relevant component of the niche is represented by supportive stromal cells that control the fate of CICs by a reciprocal cross-talk. The understanding of these cellular events could represent a significant advancement in cancer biology and treatment. Recent observations by our and other laboratories have suggested that mesenchymal stromal cells (MSC) regulate lung cancer growth and resistance, thus generating large expectations in novel anti-cancer strategies. The aim of our study was to determine whether MSC isolated from NSCLC and from non-neoplastic human lung samples possess different biologic properties and tumorigenic potential.
Methods:
Fresh samples of neoplastic and spared lungs from 58 male patients (80% smokers) affected by primary pulmonary adenocarcinoma undergoing surgical resection were processed. Stromal cells were separated from epithelial cells by negative selection using EpCAM (CD326)-based immunomagnetic sorting. After further enrichment, we could expand for at least 14 passages a population of CD90, CD105, CD73 and CD44 positive MSC from lung cancer (Lc-MSC) and non-neoplastic (Nn-MSC) lung tissue. The oncogenic potential of these cells from the same patient was tested on a Calu-3-based in vitro model of NSCLC by co-culture and conditioned media (CM) and in vivo by xenotransplantation in Balb/c Nude mice. In vivo cell tracking was achieved by pre-labeling MSC with Quantum dots 585 (Qdots). Morphometric assessment of tissue composition and immunofluorescence combined with FISH analysis of human X and Y chromosomes was performed on xenografted tumors.
Results:
Nearly 30x10[6] cells could be typically obtained after 3 passages in each case, however, compared to Nn-MSC, cultures of Lc-MSC displayed lower growth kinetic and mitotic index while higher survival and HIF-1-alpha (Hypoxia-inducible-factor-1) upregulation in response to hypoxia was observed. A larger fraction of Lc-MSC expressed transcription factors involved in stemness (Oct3/4, SOX2) and in bronchioalveolar (TTF1, ETS-1, CCL10) commitment. Co-cultures demonstrated that Lc-MSC significantly increased Calu-3 growth as compared to Nn-MSC in transwell assay and by contact. CM from Lc-MSC similarly promoted Calu-3 expansion as compared to Nn-MSC. When 2.5x10[6] Lc-MSC or Nn-MSC from the same patient were subcutaneously co-injected with Calu-3, a 38% and 17% increase in tumor volume was respectively observed, compared to the injection of an equal number of Calu-3 alone (CTRL). Lc-MSC or Nn-MSC injected alone did not generate tumors. Quantitative estimation of the in vivo expansion of neoplastic cells indicated that the addition of Lc-MSC increased by 6-fold and 29-fold Calu-3 replication compared to Nn-MSC and CTRL, respectively. Cell tracking documented that Qdots labelled MSC were located at the boundary of neoplastic epithelial glands generated by X-chromosome polysomic Calu-3 cells. A comparative molecular analysis of Lc-MSC and Nn-MSC is ongoing for the identification of distinctive signalling pathways implicated in the microenvironemental control of CIC on NSCLC development.
Conclusion:
Profound differences exist in the biology and oncogenic potential of intratumoral and normal lung MSC strongly supporting the notion that the tumor microenvironment may represent a potential target of new customized therapeutic strategies.
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ORAL07.06 - Sox2 Cooperates with Lkb1 Loss to Promote Mouse Model of Squamous Cell Lung Cancer (ID 2910)
11:39 - 11:50 | Author(s): A. Mukhopadhyay, G. Mollaoglu, B. Witt, T.G. Oliver
- Abstract
- Presentation
Background:
Squamous cell carcinoma (SCC) of the lung is the second most common subtype of lung cancer with limited treatment options and a poor survival rate. Until recently, mouse models of SCC have been limited.
Methods:
Using lentiviral delivery of Sox2 and Cre recombinase to the mouse lung, we tested the ability of Sox2 to promote tumorigenesis in multiple tumor suppressor backgrounds. Mouse lungs were imaged for tumor formation using micro-CT imaging. Resulting mouse tumors were evaluated for histological markers including Nkx2.1, Sox2, p63, cytokeratin-5, cytokeratin-14 and compared to human squamous tumors. Phospho-signaling proteins including pAkt, pErk, pStat3, pAMPK, p4EBP1 were also evaluated in mouse and human tumors by immunohistochemistry.
Results:
Expression of Sox2 specifically cooperates with loss of Lkb1 to promote squamous lung tumors. Importantly, Sox2 expression and mTOR pathway activation frequently co-occur in human squamous tumors. Mouse squamous tumors exhibit characteristic histopathology and biomarker expression similar to human SCC. They also mimic human SCCs by activation of therapeutically relevant pathways including STAT and mTOR. Sox2 expression is sufficient to induce phosphorylated Stat3 in vitro (Mukhopadhyay et al, Cell Reports, 2014). Sox2-driven tumors also exhibit immune cell infiltration consistent with other squamous lung cancer models.
Conclusion:
This mouse model of Sox2-driven squamous lung cancer may be a useful model to study immunotherapies and their mechanism of action. This model may also be used to test the contribution of additional driver alterations in SCC, as well as for preclinical drug discovery. Our data suggest mTOR, Jak-Stat and immunotherapies may be relevant targets for squamous lung cancer.
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- Abstract
Background:
Non-small-cell lung cancer (NSCLC) is featured with genetic and histopathological heterogeneity. LKB1-mutant NSCLC represents a unique and prevalent molecular subtype with limited treatment options. Originally characterized as a tumor suppressor, LKB1 phosphorylates and activates several downstream targets to inhibit cell growth; on the other hand, LKB1 also regulates cellular energy sensing and metabolic homeostasis. This raises an interesting question about how LKB1 inactivation coordinates in vivo lung tumor progression with metabolic adaptation. We have shown recently that the Kras/Lkb1 lung tumor heterogeneity results from p63-mediated ADC to SCC transdifferentiation (AST) through mixed Ad-SCC at late stage, suggesting an unexpected plasticity upon LKB1 inactivation in NSCLC. However, it remains unclear how LKB1 inactivation coordinates tumor progression with metabolic adaptation in orchestrating this tumor plasticity.
Methods:
We integratively analyze the transdifferention process of mouse lung adenocarcinoma to squamous cell carcinoma in Kras/Lkb1 Adeno-Cre nasal inhalation model as well as the lineage-defined Kras/Lkb1 model. Moreover, we have also systematically analyzed the clinical lung adenosquamous cell carcinoma to prove the findings from our animal models.
Results:
Here in Kras[G12D];Lkb1[lox/lox ](KL) mouse model, we reveal differential reactive oxygen species (ROS) levels in lung adenocarcinoma (ADC) and squamous cell carcinoma (SCC). ROS can functionally modulate the ADC-to-SCC transdifferentiation (AST). Furthermore, pentose phosphate pathway deregulation and impaired fatty acid oxidation collectively contribute to the redox imbalance and functionally affect AST. Similar tumor and redox heterogeneity also exist in human NSCLC with LKB1 inactivation. In preclinical trials towards metabolic stress, certain KL ADC can develop drug resistance through squamous transdifferentiation. This study uncovers critical redox control of tumor plasticity that may affect therapeutic response in NSCLC.
Conclusion:
LKB1-mutant tumor represents a unique and prevalent molecular subtype of NSCLC with limited treatment options. Through integrative human lung cancer sample analysis and modeling tumor development in mouse model, we have uncovered the accumulation of ROS during ADC progression, which modulates the phenotypic transition as squamous transdifferentiation and metabolic adaptation. This metabolic adaptation reflects the dynamic function of LKB1: a tumor suppressor at early lung ADC progression and an essential metabolic regulator at late phenotypic transition. The redox-controlled tumor plasticity for squamous transdifferentiation enables ADC to progress under stress, and more importantly to escape certain treatment towards cancer metabolism. The plasticity represents as a potentially important mechanism for lung cancer metabolic adaptation and drug resistance, and holds important therapeutic implications.
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ORAL07.08 - Discussant for ORAL07.05, ORAL07.06, ORAL07.07 (ID 3470)
12:01 - 12:11 | Author(s): Y. Yatabe
- Abstract
- Presentation
Abstract not provided
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ORAL 25 - Biology and Other Issues in SCLC (ID 125)
- Event: WCLC 2015
- Type: Oral Session
- Track: Small Cell Lung Cancer
- Presentations: 8
- Moderators:J. Sage, L. Montuenga
- Coordinates: 9/08/2015, 10:45 - 12:15, 605+607
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- Abstract
Background:
Given its widely metastatic nature at the time of diagnosis and the lack of effective therapies, early detection could theoretically have a beneficial impact on small cell lung cancer (SCLC) patient survival. However in the National Lung Screening Trial (NLST), there was no survival advantage for SCLC in the low dose computed tomography (LDCT) arm versus the chest radiography (CXR) arm. We investigated whether LDCT could detect SCLC and whether such screen detection offered a stage and/or survival benefit.
Methods:
Subjects randomized to the LDCT arm in NLST received three annual LDCT screens. Incident cancers were tracked with annual surveys and confirmed with medical records, with abstractors coding lung cancer stage and histology. “Best” stage was defined as pathologic stage if available, otherwise clinical stage. Deaths were tracked with the annual surveys and supplemented by the National Death Index. Cancer was denoted as screen-detected if it was diagnosed within one year of a positive screen or if it was diagnosed after a longer period but with no time gap between diagnostic procedures of more than one year. An interval cancer was defined as a cancer diagnosed within one year of a negative screen. Non-screen detected or interval cancers were denoted as non-screened if the subject did not receive any NLST screens or otherwise as post-screening.
Results:
26,722 subjects were randomized to the LDCT arm (median follow up 6.5 years; 59% men; median age at enrollment 62). 143 SCLCs were diagnosed [49 (34.2%) screen-detected, 15 (10.5%) interval, 79 (55.2%) non-screened/ post-screening]. The ratio of interval to screen detected cases was significantly higher for SCLC (15/49=0.31) than for NSCLC (29/591=0.05); p < 0.0001. 123 of 143 (86%) SCLCs were detected at late-stages (best stage III/IV); the unfavorable stage-distribution persisted among screen-detected, interval and non-screened/ post-screening cases with only 15 (10.5%) detected in early-stages. Three-year lung cancer-specific survival was 72% for early-stage versus 11% for late-stage disease. There was no significant difference in five-year survival between screen-detected, interval and non-screened/post-screening SCLCs (15.3%, 20.0% and 13.8%, respectively). Unlike NSCLC, even at small nodule sizes the proportion of screen-detected SCLCs that were late stage was very high.
Conclusion:
Analysis of SCLC detected in the NLST LDCT arm show that yearly LDCT screens do not detect a significant number of early stage SCLCs. Compared with NSCLC, a higher proportion of SCLCs are interval-detected than screen-detected. Further, there is no stage-shift or survival benefit for screen- detected SCLCs compared with interval or post-screen detected cases. To our knowledge this is the largest analysis to date of SCLC detected in a screening study. Our results indicate that in order for a screening modality to be successful for SCLC, it is necessary (but not sufficient) to be able to detect it earlier than does LDCT.
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ORAL25.02 - Vasculogenic Mimicry in Small Cell Lung Cancer (ID 2654)
10:56 - 11:07 | Author(s): K.L. Simpson, F. Trapani, R.L. Metcalf, R. Polanski, S. Williamson, R.E.B. Seftor, E.A. Seftor, A. Fusi, C.L. Hodgkinson, D. Nonaka, C.J. Morrow, M.J.C. Hendrix, F. Blackhall, C. Dive
- Abstract
Background:
Small cell lung cancer (SCLC) accounts for 15-20% of lung cancer cases worldwide and is characterised by early dissemination. Despite initial responses to chemotherapy, most patients relapse with drug resistant disease and long term survival is rare. Targeting tumour vasculature in SCLC with anti-angiogenic drugs produced disappointing results. However, angiogenesis-independent tumour vascularisation including vasculogenic mimicry (VM), warrant further investigation. VM describes the ability of aggressive tumour cells with ‘stem-like’ plasticity to adopt endothelial characteristics and form fluid conducting channel-like structures independent of host vasculature. We sought to determine the prevalence of VM in SCLC and explore associations of VM with chemotherapy sensitivity and patient outcomes. We investigated the role of a VM-associated protein, VE-Cadherin in vitro and in vivo and in SCLC CTCs. We are testing the hypothesis that VM may contribute to the high prevalence of CTCs in SCLC and components of the VM pathway may be targets for SCLC therapeutics.
Methods:
VM was evaluated using CD31/periodic acid-Schiff (PAS) staining in a tissue micro-array (TMA) from 41 limited stage SCLC chemo-naive patients and in tumours from 11 Circulating Tumour Cell (CTC) Derived Explant (CDX) models (Hodgkinson et al Nature Medicine, 2014). The relative abundance of VM channels (CD31-ve/PAS+ve) compared to host derived blood vessels (CD31+ve/PAS+ve), (VM/total vessels) in the TMA was compared to patient overall survival (OS). VM was evaluated in vitro by network formation in Matrigel (Hendrix et al., PNAS 2001) in a panel of SCLC cells lines and in H446 cells where VE-Cadherin was knocked down with shRNA. H446 cells +/- VE-Cadherin were grown in vivo as xenografts and evaluated for VM. ISET filtered, DAPI stained CTCs were immune-stained for CD45, cytokeratin and VE-cadherin and a VM score was generated.
Results:
In the TMA, a VM/Total Vessels score >10% was a poor prognostic factor for OS by univariate (p=0.011) and multivariate (p=0.014) analyses. VM was present in all CDX models provide surrogate tissues in which to study VM. Of 12 SCLC cell lines studied, H446 showed significant VE-Cadherin expression and formed networks in Matrigel; VE-Cadherin shRNA abrogated this network formation. Similarly, a pilot in vivo study demonstrated that there were fewer VM vessels when VE-Cadherin was reduced. In CTC samples 37/38 chemonaive SCLC patients contained a sub-population of VE-Cadherin expressing CTCs where the VM score ranged from 0 – 100% (median 11%, mean 21%).
Conclusion:
We present the first evidence of VM in SCLC which correlates with poor OS consistent with findings in other cancer types. VE-Cadherin is required in SCLC for VM network formation in vitro and preliminary data indicate that VE-Cadherin influences VM in vivo. Furthermore, VE-Cadherin and pan-cytokeratin co-expression was found in SCLC CTC sub-populations. We are investigating the role of VE-Cadherin in VM in SCLC and are exploring the hypotheses that VE-cadherin and VM may play a role in drug delivery and/or sensitivity and may represent an aggressive, ‘stem-like’ population that may contribute to dissemination and relapse in this highly aggressive disease.
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- Abstract
- Presentation
Background:
There were mainly two kinds of lung cancer xenograft models, xenograft models derived from stable cell lines and patient derived xenograft (PDX) models which adopted tissues resected by surgeries. However, these animal models may not reflect biological and genetic characteristics of advanced lung cancer, especially small cell lung cancer (SCLC). We utilized bronchoscopy-guided biopsy tumor tissues of advanced lung cancer to establish xenograft models and analyzed fidelity of histopathology, genetic profile and chemotherapeutic efficacy with their parental tumors. At last the molecular mechanism of drug resistance in refractory SCLC was studied.
Methods:
Primary pulmonary tumor tissues taken from bronchoscopy were implanted to NOD-SCID (nonobese diabetic-severe combined immunodeficiency disease) mice subcutaneously for model establishment and consecutive passage. The histopathology and genetic profile in samples of bronchoscopy-guided biopsy tumor tissues-derived xenograft (BDX) models and their parental tumors were detected. Parental fidelity of BDXs’ chemotherapeutic response was detected by chemosensitivity in vivo. Next generation sequencing (NGS) of target gene was taken in SCLC BDXs to analyze high-fidelity with their parental samples. Based on bioinformatic analysis, molecular mechanism of sensitive and refractory SCLC was discussed.
Results:
66 BDXs from 188 patients (35%) were successfully established. Successful rate of BDXs in SCLC was significantly higher than that in squamous cell cancer (SCC) (50.72% vs. 32.00%, p=0.005) and in adenocarcinoma (ADC) (50.72% vs. 16.22%, p=0.025). The growth rate of passage 1 BDXs in SCLC was slower than it in SCC or ADC (P<0.0001). Almost all BDXs kept similar histology, pathological marker and driver-gene mutations with their corresponding patients’ tissues. The gene mutations of which frequency was more than 10% in patient’s SCLC were kept consistent in BDXs with same genotype and frequency. Gene mutations which regulated mitogen activated protein kinase (MAPK) pathway as KRAS, KIT, MET were only detected in refractory SCLC and corresponding BDXs rather than sensitive disease. In further functional verification, the percentage of positive pERK was 100% (5/5) in refractory BDXs, but 20% (1/5) in sensitive BDXs (p=0.0476).
Conclusion:
BDXs which were successfully established with high-fidelity of histopathology, genetic profile and chemotherapeutic response could be utilized as animal models in research of unresectable lung cancer. MAPK pathway related gene mutations found in both BDXs and primary tumor tissues may be associated with resistance in refractory SCLC. PERK was promising to be used as molecular markers in genotype and prediction of chemotherapy-resistance for SCLC.
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ORAL25.04 - Discussant for ORAL25.01, ORAL25.02, ORAL25.03 (ID 3360)
11:18 - 11:28 | Author(s): C.M. Rudin
- Abstract
- Presentation
Abstract not provided
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- Abstract
- Presentation
Background:
Myeloid-derived suppressor cells (MDSCs) play a key role in microenvironment for tumor progression and have been emerged as a promising target in immunotherapy for tumor. We reported the existence and characteristics of monocytoid MDSCs in peripheral blood of patients with small-cell lung cancer (SCLC). In this study, we further identify the predictive and prognostic of MDSCs in a larger cohort of SCLC patients.
Methods:
60 healthy and 228 chemotherapy-naïve patients with SCLC participated. Peripheral venous blood samples prior to chemotherapy (baseline) and after the second cycle of chemotherapy (2[nd] cycle) were collected and detected for MDSCs (CD11b[+]HLA-DR[-]CD33[+]) by flow cytometry.
Results:
Median age of the patients was 58 years (range 18-79). MDSCs in limited-stage (n=147) and extensive-stage patients (n=81) were (16.41±8.54)% and (17.20±10.43)% respectively, higher than those in healthy control (11.04±3.76)%, P<0.001。The level of MDSCs were lower after 2[nd] cycle than those pre-treatment, (8.47±5.51)% versus (17.61±6.69)%, P<0.001. Patients with response to chemotherapy (CR+PR+SD) showed lower MDSCs level than those with progression disease at both time points, (15.85±9.07)% versus (18.42±8.89)%, P=0.026 at baseline and (8.20±5.31)% vs (10.65±6.73)%, P=0.045 after 2[nd] cycle. Patients with MDSCs level ≥22% (2 fold of healthy control) showed favorable overall survival than those with MDSCs level <22% (13.9 months versus 7.9 months respectively, log rank P=0.003). No difference regarding to median progression–free survival was observed between the two groups.
Conclusion:
MDSCs level at both baseline and after the second cycle of chemotherapy was associated with response of SCLC patients to chemotherapy and overall survival, implying it is likely a new predictive and prognostic biomarker for SCLC patients.
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ORAL25.06 - Association of Expression of PD-L1 with the Tumor Immune Microenvironment in Small Cell Lung Cancer (ID 859)
11:39 - 11:50 | Author(s): H. Yu, A. Badzio, T.A. Boyle, D. Chan, C.J. Rivard, X. Lu, A.A. Kowalewski, K. Ellison, F.R. Hirsch
- Abstract
- Presentation
Background:
Small cell lung cancer (SCLC) accounts for 15% of all lung cancers and has been under-studied relative to novel therapies. Therapeutic antibodies to immune checkpoints are showing promising clinical results. Programmed death-ligand 1 (PD-L1), which can be expressed on many cancer and immune cells, plays an important role in blocking the cancer immunity cycle by binding programmed death-ligand 1 receptor (PD-1), which is a negative regulator of T-lymphocyte activation. Since knowledge about PD-L1 expression in SCLC is limited, we aimed to characterize PD-L1 expression in a cohort of 98 SCLC patients.
Methods:
PD-L1 protein expression and mRNA levels were determined by immunohistochemistry (IHC, SP142, Spring Bioscience) and mRNA in situ hybridization (ISH) in primary tumor tissue microarrays obtained from 98 SCLC patients. Membranous staining of PD-L1 protein and mRNA expression on tumor cells and protein expression on tumor-infiltrating immune cells (TIICs) were scored separately using semi-quantitative scores (H-score 0-300 and RNA score 0-4). An H-score ≥ 5 and an RNA score > 2 were defined as the cutoffs for PD-L1 protein and RNA expression positivity. The degree of TIICs was semi-quantitatively scored on hematoxylin and eosin-stained TMA slides as having “0” (no), “1” (mild), “2” (moderate), or “3” (marked) infiltration. The data was analyzed using the Fisher’s exact test, Spearman correlation, two-sample t-test, log-rank test and Kaplan- Meier survival analysis with significance level assumed to be 0.05.
Results:
3.16% of cases (3/95) were positive for PD-L1 protein expression in tumor cells, and 30.21% were positive for PD-L1 in TIICs (29/96, p<0.0001). PD-L1 mRNA expression was positive in 15.46% of the tumor cells (15/97). PD-L1 protein and mRNA expression on tumor cells demonstrated a positive correlation (p<0.0001, r=0.431). PD-L1 mRNA expression on tumor cells positively correlated with PD-L1 protein expression on TIICs (p<0.0001, r=0.354). The degree of TIICs positively correlated with both PD-L1 protein expression in tumor cells (p=0.011, r=0.264) and PD-L1 mRNA expression in tumor cells (p<0.0001, r=0.405). The degree of TIICs positively correlated with PD-L1 protein expression in TIICs (p<0.0001, r=0.625). The only significant association observed between PD-L1 expression with clinical characteristics or prognosis of the 78 SCLC patients with clinical data, was between age of patients and PD-L1 protein (p<0.0001) and mRNA expression (p=0.0006) on tumor cells.
Conclusion:
A subset of SCLCs is characterized by positive PD-L1 protein and/or mRNA expression in tumor cells and TIICs. PD-L1 mRNA expression was more frequently positive than PD-L1 protein expression in the tumor cells. PD-L1 protein expression was expressed more in TIICs than tumor cells. Higher PD-L1 protein and mRNA expression correlated with more infiltration of TIICs. PD-L1 expression represents the immune response in SCLC. The microenvironment may play a major role on the PD-1/PD-L1 pathway of SCLC. SCLC Patients with PD-L1 expression may respond to anti-PD-L1 treatment.
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ORAL25.07 - DNA Methylation in Small Cell Lung Cancer Defines Distinct Disease Subtypes and Correlates with High Expression of EZH2 (ID 3031)
11:50 - 12:01 | Author(s): J. Poirier, E. Gardner, N. Connis, A. Moreira, E. De Stanchina, C. Hann, C.M. Rudin
- Abstract
- Presentation
Background:
Small cell lung cancer (SCLC) is an aggressive neuroendocrine lung tumor characterized by extreme plasticity, high metastatic potential, and capacity for acquired resistance to chemotherapy. Despite significant advances in our understanding of SCLC genetics and etiology, the epigenetics of this deadly disease remain under studied. This study profiles DNA methylation in primary SCLC, patient-derived xenografts (PDX) and cell lines at single-nucleotide resolution.
Methods:
This study profiled DNA methylation at single-nucleotide resolution in 47 extensively characterized SCLC samples, including 34 fresh frozen primary SCLC tumors as well as 6 distinct primary patient-derived xenografts and 7 cell lines using the Illumina Human Methylation 450k Bead Chip array. Importantly, 24 primary SCLC in this study have previously been analyzed by whole exome sequencing and RNAseq, allowing integrated analysis of these data types with measurements of DNA methylation. We applied unsupervised clustering, discrete and locally clustered differential methylation analysis, correlation with gene expression, spacial correlation with genomic features, and interrogated the role of the EZH2 methyltransferase in SCLC using bioinformatic and pharmacologic approaches.
Results:
Unsupervised clustering of all samples revealed that PDX clustered with primary SCLC, while cell lines were easily discriminated. We explored this phenomenon further and found that while the top differentially methylated CpGs in both PDX and cell lines were >80% concordant with primary SCLC, only PDX maintained high concordance across larger probe lists. Unsupervised clustering of primary SCLC revealed three distinct subgroups at both the DNA methylation and gene expression levels that correlated with expression of the neurogenic transcription factors ASCL1 and NEUROD1. The chromatin modifier EZH2 was expressed >12-fold higher in SCLC than in normal lung. In addition to the high expression observed in SCLC compared to normal lung, we observed a significant correlation between median EZH2 gene expression and promoter methylation using data from The Cancer Genome Atlas (TCGA). Overall, EZH2 expression in SCLC is greater than or comparable to that of any other tumor type represented in TCGA. EZH2 protein expression was detected by Western blot in 15/17 SCLC PDXs (88%). We assessed the efficacy of the potent EZH2 inhibitor EPZ-5687 in the LX92 SCLC PDX in vivo. EPZ-5687 was well-tolerated and demonstrated remarkable efficacy at 100 mg/kg either QD or BID.
Conclusion:
DNA methylation patterns in primary SCLC are more closely mirrored by those found in PDX, compared to cell lines, including PDX lines of very high passage. Distinct epigenetic subtypes could be observed in SCLC, even among histologically indistinguishable samples with similar mutation profiles. SCLC is notable for consistent high level DNA methylation clustered in promoters containing CpG islands. Promoter methylation in SCLC is distinct from other lung cancers and correlates strongly with high-level expression of the histone methyltransferase gene EZH2. Pharmacologic inhibition of EZH2 in a SCLC PDX markedly inhibited tumor growth. These findings point to a critical role of EZH2 in SCLC tumor biology and support further preclinical efficacy studies in models of SCLC.
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ORAL25.08 - Discussant for ORAL25.05, ORAL25.06, ORAL25.07 (ID 3361)
12:01 - 12:11 | Author(s): C. Dive
- Abstract
Abstract not provided
Author of
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MS 07 - SCLC Biology & Models (ID 25)
- Event: WCLC 2015
- Type: Mini Symposium
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:D. Carney, C.M. Rudin
- Coordinates: 9/07/2015, 14:15 - 15:45, Mile High Ballroom 4a-4f
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MS07.03 - Pre-Clinical Mouse Models of SCLC to Identify and Validate New Therapeutic Targets (ID 1874)
14:50 - 15:05 | Author(s): J. Sage
- Abstract
- Presentation
Abstract:
Small cell lung cancer (SCLC) is a neuroendocrine subtype of lung cancer characterized by a fast growth rate, extensive dissemination, and rapid resistance to chemotherapy. Survival rates are dismal and have not significantly improved in the past few decades. The group of Roman Thomas and Martin Peifer sequenced the genomes of over 100 human SCLC, which demonstrates universal inactivation of p53 and RB and identified inactivating mutations in NOTCH family genes in ~25% of tumors. Accordingly, we found that activation of Notch signaling in a pre-clinical SCLC mouse model dramatically reduces the number of tumors and extends the survival of the mutant mice. In addition to suppressing proliferation, active Notch inhibits neuroendocrine gene expression in SCLC cells. Thus, Notch plays a key tumor suppressive role in SCLC and strategies to re-activate Notch in SCLC tumors may be beneficial to patients (George, Lim, et al., in press). At the histological level, SCLC tumor cells are often viewed as homogeneous. These studies and previous studies (e.g. Calbo et al., Cancer Cell, 2011 – Berns lab) have identified several levels of intra-tumor heterogeneity in SCLC, which may contribute significantly to SCLC aggressive nature and resistance to therapy. We will also discuss the existence and the role of several subpopulations of SCLC tumor cells involved in the long-term propagation of this cancer type, the rapid acquisition of chemoresistance, and metastasis. A better understanding of the molecular underpinnings of these cellular heterogeneity may help identify novel therapeutic targets in SCLC.
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