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J.V. DeGregori
Moderator of
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ORAL 42 - Drug Resistance (ID 160)
- Event: WCLC 2015
- Type: Oral Session
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 7
- Moderators:R.C. Doebele, J.V. DeGregori
- Coordinates: 9/09/2015, 18:30 - 20:00, Mile High Ballroom 4a-4f
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ORAL42.01 - ALK-Rearranged NSCLC Adaptive Cell Plasticity with Early Onset TGFb2 Mediated Precision Drug Escape through PRC-2 Epigenetic Reprogramming (ID 3111)
18:30 - 18:41 | Author(s): P.C. Ma, L. Yin, W. Zhang, I. Shi, X. Wu, J. Phillips, H. Choi, H. Makishima, D. Lindner, Y. Feng, F. Almeida, J.P. Maciejewski, Y. Saunthararajah, Z. Zhang
- Abstract
Background:
ALK-tyrosine kinase inhibitor (ALKi) is currently the standard precision therapy for advanced ALK(2p23)-rearranged (ALK+) non-small cell lung cancer (NSCLC), often with impressive primary responses. Nonetheless, acquired clinical resistance even in excellent/complete responders still develops ultimately with time; thus hampering long term benefits. Classic tumor rebiopsy studies that deciphered drug-resistance mechanisms focused on the “late phase” resistance at time of clinical progression in treated ALK+ NSCLC. These studies identified diverse pattern of drug-resistance mechanisms, including numerous non-dominant secondary drug-resistant ALK kinase mutations (e.g. C1156Y and L1196M), bypass signaling pathways (e.g. EGFR, KIT signaling), ALK gene amplification, and overexpression of microenvironmental factors (e.g. EGF, TGF-α, HGF). The mechanisms underlying the initial and early emergence of drug-resistance under precision therapy are poorly understood.
Methods:
EML4-ALK(+) H3122 and patient-derived ALKi acquired resistant biopsied-lung tumor tissue cells were used to investigate drug-escape mechanisms. Stem cell transcription factors QPCR array and RNA-sequencing profiling were performed on H3122 cells under ALKi up to day 14, compared with untreated and drug-washout controls. MTS cell viability assays using ALKis, in vitro and in vivo tissues QPCR assays, as well as in vivo xenograft IHC analyses were also performed. Patient-derived bronchoscopic biopsied NSCLC tissues (Ma0083) during ALKi resistance was procured and propagated in cell culture in accordance with approved institutional protocols.
Results:
We identified that H3122 cells displayed cell plasticity and can escape ALKi’s (TAE-684, crizotinib) remarkably early after precision therapy initiation, with augmented prosurvival signaling via upregulated autocrine TGFβ2 signaling, but not TGFβ1 or β3, as early as day 14 post-treatment. We validated using both in vitro and in vivo models the upregulated cascade of tumoral TGFβ2-HOXB3-mitochondrial priming during adaptive drug-escape. The early onset drug-resistant cells were marked by reversible autocrine TGFβ2-mediated transcriptome reprogramming with reversibly enhanced EMT-ness and cancer stemness. Moreover, RNA-seq findings strongly suggest a “reverse Warburg” cell state during adaptive drug-escape. The adaptive cellular plasticity was verified also in patient-derived bronchoscopic biopsied NSCLC tissues (Ma0083) with ALKi resistance. Interestingly, inhibiting mitochondrial priming using dual BCL-2/BCL-xL BH3-mimetics ABT-263 was effective to suppress early drug-escape, but not with the BCL-2-specific agent ABT-199, suggesting BCL-xL is a key target. Importantly, we also identified upregulated HOXB3 expression correlated with the early adaptive drug-resistance cell state, emerged through dynamic remodeling of EZH2/UTX in the polycomb repressive complex-2 (PRC-2). Deregulated EZH2/UTX epigenetic balance impacted the poised chromatin state of HOXB3 promoter H3K27me3/H3K4me3 histone marks. Early drug-escape cell state was correlated with suppressed EZH2 expression, at mRNA and also protein levels, in both in vitro and in vivo models. Finally, our results showed that specific EZH2 inhibitor GSK126 promoted ALKi drug-resistance, while UTX inhibitor GSK-J4 eradicated ALKi adaptive drug-resistance.
Conclusion:
Our study findings provide novel insights into the initial emergence and evolution of ALK precision drug-resistance and highlighted the significance of understanding the role of adaptive tumor cell plasticity in the early drug-escape process with important therapeutic implications. Therapeutic modulation of the coordinated EZH2/UTX balance in the PRC-2 complex can profoundly impact ALKi drug treatment outcome.
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ORAL42.02 - Qualitative and Quantitative Heterogeniety in Acquiring Resistance to EGFR Kinase Inhibitors in Lung Cancer (ID 572)
18:41 - 18:52 | Author(s): K. Suda, I. Murakami, K. Sakai, H. Mizuuchi, K. Sato, K. Tomizawa, K. Nishio, T. Mitsudomi
- Abstract
- Presentation
Background:
Acquisition of resistance to EGFR- tyrosine kinase inhibitors (TKIs) is one of important issues in lung cancer researches. Several resistance mechanisms have been identified. However, inter-tumor heterogeneity in acquisition of resistance to EGFR-TKIs is currently unclear.
Methods:
Eleven autopsied patients who developed acquired resistance to EGFR-TKI monotherapy were included in this study. All patients harbored activating EGFR mutations (exon 19 deletion or L858R mutation), and developed acquired resistance to EGFR-TKI after initial response to the drug. Details of patient characteristics are summarized in Table 1. The resistance mechanisms of seven patients have been reported in our previous analyses (Suda K, et al. Clin Cancer Res 2010, and Suda K, et al. APLCC 2014). In this study, we analyzed acquired resistance mechanisms in twenty-eight tumor samples obtained from the four additional patients using target sequencing technique by next-generation sequencer.
Results:
Among eleven patients, four developed T790M EGFR secondary mutation in all TKI-refractory lesions. One patient developed MET amplification in all TKI-refractory lesions. Three patients harbored both TKI-refractory lesions with T790M mutation and those with MET amplification. The other three patients showed respective resistance mechanisms (Table 1).Table 1. Summary of resistant mechanisms in eleven patients.
In the target sequence analysis, allele count data were further analyzed in tumor samples with T790M mutation, and we observed diverse T790M/activating EGFR mutation allele ratio ranging from 2 – 51%. In the analysis for time to treatment failure (TTF), we observed longer TTF in patients who developed single resistance mechanism compared with those who developed multiple resistance mechanisms (Fig. 1; p = 0.055). Figure 1Pt. ID Age/Sex Pack-Year Resistant Mechanisms TTF (m) C1 57/F 0 T790M or MET 13.8 C2 48/F 0 T790M or MET 11.0 C3 58/M 34 MET 14.5 C4 75/M 0 T790M 43.9 C5 93/F 0 T790M 14.8 C6 62/M 26 T790M 9.1 P1 86/F 0 T790M 10.8 P2 72/M 27 T790M or MET 3.8 P3 89/F 0 EGFR loss with MET or Unknown 9.0 P4 84/F 0 Unknown 22.6 A1 76/F 0 SCLC transformation or T790M 5.0
Conclusion:
In this study, we observed qualitative heterogeneity and quantitative heterogeneity of T790M allele ratio in acquisition of resistance to EGFR-TKIs in lung cancers. Qualitative heterogeneity in resistance mechanisms would have a correlation with TTF of EGFR-TKIs.
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ORAL42.03 - Discussant for ORAL42.01, ORAL42.02 (ID 3441)
18:52 - 19:02 | Author(s): L. Heasley
- Abstract
- Presentation
Abstract not provided
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ORAL42.04 - Rictor Alterations Elicit Mechanisms of Survival Advantage and Resistance to Targeted Therapy in Non-Small Cell Lung Cancer (NCSLC) (ID 2991)
19:02 - 19:13 | Author(s): D. Ruder, V. Papadimitrakopoulou, L. Shen, R. Herbst, L. Girard, J. Wang, G.M. Frampton, V. Miller, J. Minna, W.K. Hong, I.I. Wistuba, J.G. Izzo
- Abstract
- Presentation
Background:
Rictor (RPTOR independent companion of MTOR, complex 2) is a highly conserved protein and is a critical component for assembly and functionality of the mTORC2 complex. Alterations of the PI3K/mTOR/AKT pathway are hallmark of many cancer types, underscoring the potential important role of Rictor. The goal of our current study was to characterize the functional consequences of genomic alterations of Rictor in advanced refractory NSCLC. Our preliminary data suggest that Rictor alterations have the potential to, not only signal canonically (via activation of AKT), but also provide cancer cells with alternate, more advantageous oncogenic signaling via non-canonical mechanisms.
Methods:
We correlated genomic data (DNA next generation sequencing (NGS), Foundation Medicine, Inc) gene expression profiling, and clinical outcome in the context of the ongoing BATTLE-2 clinical trial of targeted therapies in chemo-refractory NSCLC(198 cases). We further (1) surveyed early stage NSCLC cases(230 cases) in The Cancer Genome Atlas (TCGA) database to perform two-way hierarchical clustering comparing gene expression profiling in amplified vs diploid cases; (2) utilized a single-nucleotide polymorphism array to select Rictor amplified and diploid NSCLC cell lines; (3) assessed Rictor protein and RNA expression by Western blot and qRT-PCR, respectively; (4) performed Rictor knockdown (siRNA), and (5) performed drug sensitivity to targeted therapies by MTS assay.
Results:
In the Battle-2 cases, we identified 15% of Rictor alterations (9% gene amplifications, 6.6% mutations, non-concomitant). Among the mutations, 1 was mapped to an N-terminal phosphorylation site, while all others are of unknown significance to date. Rictor alterations were significantly associated with lack of 8-week disease control in the AKTi+MEKi therapeutic arm. In the TCGA we found: (1) 10% Rictor amplifications and 3% mutations; (2) significant correlation between amplification and elevated Rictor gene expression; (3) a putative functional gene expression signature associated with Rictor amplification. In diploid cell lines we found concordance between AKT phosphorylation and activation of other downstream mTORC2 targets (i.e. SGK1 and PKCα), but in Rictor amplified cell lines we witnessed a discordant activation of these pathways. Furthermore, following Rictor knockdown in our amplified cell lines, a significant reduction of colony formation, migratory, and invasive potential was seen in a pathway-differential manner. Thus, suggesting that Rictor amplifications may provide survival advantage in select cancer cells by tipping the signaling balance toward a non-canonical oncogenic pathway (AKT-independent[I1] ).Also in a differential pathway manner, Rictor gene amplification and overexpression contributed to resistance to a number of targeted therapies
Conclusion:
Rictor alterations may constitute a potential novel mechanism of targeted therapy resistance via the activation of non-canonical signaling pathways. These alterations could define new molecular NSCLC subtypes with distinct biology that expose unique avenues for therapeutic implication. Ongoing studies are exploring therapeutic vulnerabilities, non-canonical signaling and Rictor mutations.
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ORAL42.05 - <em>SMARCA4</em>/BRG1 Is a Biomarker for Predicting Efficacy of Cisplatin-Based Chemotherapy in Non-Small Cell Lung Cancer (NSCLC) (ID 849)
19:13 - 19:24 | Author(s): E.H. Bell, A.R. Chakraborty, X. Mo, Z. Liu, K. Shilo, S. Kirste, P. Stegmaier, M. McNulty, N. Karachaliou, R. Rosell, G. Bepler, D.P. Carbone, A. Chakravarti
- Abstract
Background:
Adjuvant platinum-based chemotherapy remains a primary treatment of non-small-cell lung cancer (NSCLC); however, identification of predictive biomarkers is critically needed to improve the selection of patients who derive the most benefit. In this study, we hypothesized that decreased expression of SMARCA4/BRG1, a known regulator of transcription and DNA repair, is a predictive biomarker of increased sensitivity to platinum-based therapies in NSCLC. Moreover, this study also sought to confirm the prognostic role of SMARCA4/BRG1 in NSCLC.
Methods:
The prognostic value of SMARCA4 expression levels was tested using a microarray dataset from the Director’s Challenge Lung Study (n=440). Its predictive significance was determined using a gene expression microarray dataset (n=133) from the JBR.10 trial, and RT-PCR data from 69 patients enrolled on the MADe-IT trial and 33 platinum-treated patients from an institutional cohort.
Results:
In the Director's challenge study, low expression of SMARCA4 was found to be associated with poor overall survival compared to high and intermediate expression (P = 0.006). Upon multivariate analysis, compared to high, low SMARCA4 expression predicted an increased risk of death and confirmed its prognostic significance (HR=1.75; P=0.002). In the JBR.10 trial, improved five-year disease-specific survival was noted only in patients with low SMARCA4 expression when treated with adjuvant cisplatin/vinorelbine (HR 0.1, P= 0.001 (low); HR 1.1 , P= 0.762 (high)). An interaction test showed significance (P=0.007). In addition, a trend toward improved progression-free survival was noted only in patients with low SMARCA4 receiving a carboplatin- versus a non-carboplatin-based regimen in the MADe-IT trial. Figure 1 Fig1. Low SMARCA4 correlates with improved disease-specific survival with adjuvant cisplatin-based chemotherapy in the JBR.10 trial.
Conclusion:
Although decreased expression of SMARCA4/BRG1 is significantly associated with worse prognosis, it is a novel significant predictive biomarker for increased sensitivity to platinum-based chemotherapy in NSCLC patients.
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ORAL42.06 - Cancer Stem Cells: Targeting Aldehyde Dehydrogenase 1 (ALDH1) as a Novel Strategy in Cisplatin Resistant Non-Small Cell Lung Cancer? (ID 2724)
19:24 - 19:35 | Author(s): L. Mac Donagh, S.G. Gray, K.J. O'Byrne, S. Cuffe, S.P. Finn, M.P. Barr
- Abstract
- Presentation
Background:
Cisplatin is the backbone of chemotherapeutic treatment of lung cancer. Unfortunately the development of resistance has become a major challenge in the use of this cytotoxic drug. Understanding the mechanisms underlying this resistance phenotype may potentially result in the development of novel agents that may enhance the sensitivity of cisplatin chemotherapy in the clinical setting. The root of this resistance is hypothesized to be due to the presence of a rare cancer stem cell (CSC) population within the tumour that can reform a heterogenic tumour, resulting in recurrence and resistance following cisplatin chemotherapy.
Methods:
An isogenic model of cisplatin resistance was established by chronically exposing a panel of NSCLC cell lines (H460, SKMES, H1299) to cisplatin for 12months, thereby creating cisplatin resistant (CisR) sublines and their corresponding age-matched parental (PT) cells. To identify a CSC population within the resistant sublines, PT and CisR cell lines representing the three classifications of NSCLC were stained for ALDH1 using the Aldefluor kit (Stemcell Technologies). ALDH1 positive (+ve) and negative (-ve) subpopulations were isolated and their functional characteristics assessed. Proliferation and survival of ALDH1+ve fractions in response to cisplatin was assessed using BrdU and clonogenic survival assays relative to ALDH1-ve cells. ALDH1 subpopulations were examined for asymmetric division and expression of the human embryonic stem cell markers Nanog, Oct-4, Sox-2, Klf-4 and c-Myc and CD133. To confirm that this ALDH1+ve population is associated with cisplatin treatment, PT and CisR cells were chronically exposed to high dose cisplatin for 2 weeks and stained for ALDH1 and re-assessed for stemness qualities. Apoptosis and clonogenic survival of PT and CisR cells was assessed in response to selective inhibition of ALDH1 using diethylaminobenzaldehyde (DEAB) in combination with cisplatin. Xenograft studies in NOD/SCID mice are currently under investigation to examine the tumourigenic potential of isolated subpopulations of ALDH1.
Results:
A significant ALDH1+ve population was detected in CisR sublines, but not in their PT counterparts. Characterisation of the ALDH1+ve subpopulation confirmed enhanced expression of stemness markers, increased resistance and clonogenic survival in response to cisplatin compared to their ALDH1-ve counterparts, and the ability to asymmetrically divide. Chronic cisplatin treatment of the PT cell lines for 2 weeks increased resistance to cisplatin, increased stemness marker expression and induced the emergence of an ALDH1+ve population. Chronic high dose cisplatin treatment significantly expanded the ALDH1+ve population in the CisR cell lines. Importantly, inhibition of ALDH1 activity, with DEAB, decreased the mean cell viability, clonogenic survival capacity and increased cisplatin-induced apoptosis of the CisR cells when used in combination with cisplatin, an effect not seen in the PT cells.
Conclusion:
In this study, we have demonstrated the existence of a putative CSC population within our model of isogenic cisplatin resistant cell lines and suggest a role for ALDH1 inhibition as a potential therapeutic strategy in re-sensitizing chemoresistant lung cancer cells to the cytotoxic effects of cisplatin. Further studies will focus on re-purposing of FDA-approved ALDH1 inhibitor, Disulfiram (Antabuse), used in the treatment of chronic alcoholism as a potential combination therapy to prime chemoresistant cells to cisplatin.
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ORAL42.07 - Discussant for ORAL42.04, ORAL42.05, ORAL42.06 (ID 3442)
19:35 - 19:45 | Author(s): S. Yano
- Abstract
- Presentation
Abstract not provided
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Author of
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MINI 09 - Drug Resistance (ID 107)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:L. Villaruz, J. Minna
- Coordinates: 9/07/2015, 16:45 - 18:15, 205+207
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MINI09.01 - Inhibiting Tankyrase Prevents Epithelial-To-Mesenchymal Transition and Synergizes with EGFR-Inhibition in Wnt-Dependent NSCLC Lines (ID 2850)
16:45 - 16:50 | Author(s): J.V. DeGregori
- Abstract
Background:
Despite their promise, therapies targeting driver receptor tyrosine kinases (RTKs) rarely produce complete responses and have shown modest clinical benefit in NSCLC. This suggests the presence of escape mechanisms that allow cells to survive and proliferate despite inhibition of an oncogenic driver.
Methods:
Using a genome-wide shRNA screen, we identified that the canonical Wnt/β-catenin pathway contributes to the survival of NSCLC cells during inhibition of the epidermal growth factor receptor (EGFR). In order to evaluate the effects of inhibiting the Wnt pathway on EGFR-inhibited cells, we categorized NSCLC cell lines as “Wnt-responsive” or “Wnt-non-responsive” based on their ability to upregulate β-catenin-dependent targets in response to treatment with exogenous Wnt3a. Using both shRNA knockdown and a novel tankyrase inhibitor, AZ1366, we evaluated the ability of tankyrase inhibition to synergize with EGFR-inhibition in multiple Wnt-responsive and Wnt-non-responsive cell lines. We then evaluated the effects of the combination of gefitinib and AZ1366 on the survival and tumor progression in an orthotopic mouse model. In order to comprehensively query transcriptional changes brought about by treatment, we performed RNA-seq on cells treated with gefitinib, AZ1366, or the combination of the two drugs.
Results:
We have demonstrated that inhibition of tankyrase, a key player in the canonical Wnt pathway, significantly increases the induction of senescense and/or apoptosis mediated by EGFR-inhibitors in cell lines with a Wnt-responsive phenotype, and that the ability of the tankyrase inhibitor to synergistically eliminate NSCLC cells is dependent on its actions within the canonical Wnt pathway. In Wnt-non-responsive cell lines, tankyrase inhibition did not synergize with inhibition of EGFR. We have further demonstrated that Wnt-responsive cell lines show evidence of EMT in response to Wnt ligand stimulation, and that this can be prevented with tankyrase-inhibitor treatment. Additionally, we have shown that mice orthotopically implanted with Wnt-responsive cell lines and treated with a combination of a tankyrase inhibitor and an EGFR inhibitor have a substantially reduced tumor burden and a significant improvement in survival when compared to treatment with an EGFR inhibitor alone. When Wnt-non-responsive cell lines were used, we noted no improvement in survival or reduction in tumor burden. RNA-seq analysis revealed that while most transcriptional changes present in the combination were driven by gefitinib, AZ1366 had the effect of significantly amplifying many of the changes thought to be instrumental in resistance to EGFR inhibition including increased expression of TP53 and apoptosis signaling machinery, increased expression of NF-kB signaling components, and a strong decrease in cell cycle drivers. Furthermore, treatment with AZ1366 alone resulted in decreased expression of Axl and its ligand, Gas6, a known mechanism of resistance to EGFR inhibition.
Conclusion:
Taken together, these results indicate that tankyrase inhibition impinges on multiple mechanisms of escape from EGFR-inhibition, and that its ability to synergize with EGFR-inhibition is dependent on its actions within the canonical Wnt pathway. As the goal of these studies is the development of combination therapies with EGFR inhibition, this suggest tankyrase as a promising target in the subset of NSCLC with known dependencies on signaling through the canonical Wnt pathway.
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MINI 14 - Pre-Clinical Therapy (ID 119)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:L. Fernandez-Cuesta, A.F. Gazdar
- Coordinates: 9/08/2015, 10:45 - 12:15, Mile High Ballroom 2c-3c
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MINI14.05 - Discussant for MINI14.01, MINI14.02, MINI14.03, MINI14.04 (ID 3341)
11:05 - 11:15 | Author(s): J.V. DeGregori
- Abstract
- Presentation
Abstract not provided
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P1.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 233)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P1.04-056 - Use of Pooled shRNA Synthetic Lethal Screens within an In Vivo Murine Model to Identify Microenvironment-Dependent Lung Cancer Genes (ID 3140)
09:30 - 09:30 | Author(s): J.V. DeGregori
- Abstract
Background:
Lung cancer remains the leading cause of cancer-related deaths worldwide. While significant knowledge has been gained regarding the characterization of mutational drivers in NSCLC, much less is known regarding interactions between tumor cells and the surrounding microenvironment that are critical for tumor progression. Additionally, a significant limitation in current understanding is the lack of knowledge regarding which tumor gene products are necessary for promoting cell survival in the context of the tumor microenvironment. We hypothesize that the use of pooled shRNA synthetic lethal screens within an in vivo murine model will allow for the elucidation of targetable microenvironment-dependent genes.
Methods:
We generated a custom murine shRNA lentiviral library targeting 250 genes implicated in the communication between cancer cells and the microenvironment, which was used to transduce two murine cell lines: Lewis Lung carcinoma (LLC) and CMT167 cells. Following puromycin selection of cells harboring incorporated shRNA’s of interest, populations were expanded and designated for in vitro versus in vivo replication and growth. Selected cells were allocated to either in vitro passage vs direct in vivo injection into the lungs of 18 week-old syngeneic C57BL6 mice. After 4 weeks, cells were harvested and gDNA was isolated. Sequencing and quantitation of shRNA was performed using an Illumina deep-sequencing platform. Both raw and normalized read counts were assessed and analyzed to determine the relative representation of a particular shRNA within an in vitro or in vivo sample. Following quality control assessments which demonstrated adequate read count numbers per sample, and appropriate correlation of sample similarity per groups, direct comparisons between in vitro and in vivo samples were performed.
Results:
Multiple gene candidates were identified and largely reproducible via either rank analysis, mean, or t-test analyses. Candidate genes included multiple chemokines, and their receptors, matrix proteases, complement factors, and growth factor receptors.
Conclusion:
These results suggest a list of genes that are both intriguing and diverse, pointing toward gene products that would not have been previously predicted to influence cancer cell survival and growth through a lung cancer cell-autonomous fashion. Furthermore, these genes appear to potentially interact with multiple compartments of the tumor microenvironment including the extracellular matrix, cytokine milieu, vascular structures (complement factors), and the adaptive immune system. Validation of specific gene targets are ongoing through assessment of tumor growth comparing murine cell lines transfected with individual shRNA’s of interest vs control tumor cells. Furthermore, parallel pooled shRNA synthetic lethal screens within selectively adaptive immune-deficient models are currently in progress.
