Genome-wide Analysis Identifies Nuclear Factor 1C as a Novel Transcription Factor and Potential Therapeutic Target in Small Cell Lung Cancer

BACKGROUND

Recent insights regarding mechanisms mediating stemness, heterogeneity, and metastatic potential of lung cancers have yet to be fully translated to effective regimens for the treatment of these malignancies. This study sought to identify novel targets for lung cancer therapy.

METHODS

Transcriptomes and DNA methylomes of 14 SCLC and 10 NSCLC lines were compared to normal human small airway epithelial cells (SAEC) and induced pluripotent stem cell (iPSC) clones derived from SAEC. SCLC lines, lung iPSC (Lu-iPSC), and SAEC were further evaluated by DNase I hypersensitivity (DHS-seq). Changes in chromatin accessibility and depths of transcription factor (TF) footprints were quantified using Bivariate analysis of Genomic Footprint. Standard techniques were used to examine growth and tumorigenencity as well as changes in transcriptomes and glucose metabolism of SCLC cells following Nuclear Factor 1C (NFIC) knockdown, and to examine NFIC expression in SCLC cells following exposure to BET inhibitors.

RESULTS

Significant commonality of transcriptomes and DNA methylomes was observed between Lu-iPSC and SCLC; however, this analysis was uninformative regarding pathways unique to lung cancer. Linking results of DNase-seq to RNA-seq enabled identification of networks not previously associated with SCLC. When combined with footprint depth, NFIC, a transcription factor not previously associated with SCLC, had the highest score of occupancy at open chromatin sites. Knockdown of NFIC impaired glucose metabolism, decreased stemness, and inhibited growth of SCLC cells in-vitro and in-vivo. ChIP-seq analysis identified numerous sites occupied by Bromodomain-containing protein 4 (BRD4) in the NFIC promoter region. Knock-down of BRD4 or treatment with Bromodomain and extra-terminal domain (BET) inhibitors (BETi) markedly reduced NFIC expression in SCLC cells and SCLC PDX models. Approximately 8% of genes downregulated by BETi treatment were repressed by NFIC knockdown in SCLC, while 34% of genes repressed following NFIC knockdown were also downregulated in SCLC cells following BETi treatment.

CONCLUSIONS

NFIC is a key TF and possible mediator of transcriptional regulation by BET family proteins in SCLC. Our findings highlight the potential of genome-wide chromatin accessibility analysis for elucidating mechanisms of pulmonary carcinogenesis and identifying novel targets for lung cancer therapy.

Characterization of pleural mesothelioma by hierarchical clustering analyses using immune cells within tumor microenvironment

INTRODUCTION

Over the past decade, classifications using immune cell infiltration have been applied to many types of tumors; however, mesotheliomas have been less frequently evaluated.

METHODS

In this study, 60 well-characterized pleural mesotheliomas (PMs) were evaluated immunohistochemically for the characteristics of immune cells within tumor microenvironment (TME) using 10 immunohistochemical markers CD3, CD4, CD8, CD56, CD68, CD163, FOXP3, CD27, PD-1 and TIM-3. For further characterization of PMs, hierarchical clustering analyses using these 10 markers were performed.

RESULTS

Among the immune cell markers, CD3 (P < 0.0001), CD4 (P = 0.0016), CD8 (P = 0.00094), CD163+ (P = 0.042) and FOXP3+ (P = 0.025) were significantly associated with unfavorable clinical outcome. Immune checkpoint receptor expressions on tumor-infiltrating lymphocytes such as PD-1 (P = 0.050), CD27 (P = 0.014) and TIM-3 (P = 0.0098) were also associated with unfavorable survival. Hierarchical clustering analyses identified three groups showing specific characteristics and significant associations with patient survival (P = 0.011): the highest number of immune cells (ICHigh); the lowest number of immune cells, especially CD8+ and CD163+ cells (ICLow); and intermediate number of immune cells (ICInt). ICHigh tumors showed significantly higher expression of PD-L1 (P = 0.00038). Cox proportional hazard model identified ICHigh [hazard ratio (HR) = 2.90] and ICInt (HR = 2.97) as potential risk factors compared with ICLow. Tumor CD47 (HR = 2.36), tumor CD70 (HR = 3.04) and tumor PD-L1 (HR = 3.21) expressions were also identified as potential risk factors for PM patients.

CONCLUSION

Our findings indicate immune checkpoint and/or immune cell-targeting therapies against CD70-CD27 and/or CD47-SIRPA axes may be applied for PM patients in combination with PD-L1-PD-1 targeting therapies in accordance with their tumor immune microenvironment characteristics.

Pulmonary Metastasectomy for Adrenocortical Carcinoma-Not If, but When

BACKGROUND

Adrenocortical carcinoma (ACC) commonly metastasizes to the lungs, and pulmonary metastasectomy (PM) is utilized due to limited systemic options.

METHODS

All ACC patients with initially only lung metastases (LM) from a single institution constituted this observational case series. Kaplan-Meier and Cox proportional hazard analyses evaluated the association with potential prognostic factors and outcomes. Overall survival (OS) was calculated from the date of the PM or, in those patients who did not undergo surgery, from the development of LM.

RESULTS

A total of 75 ACC patients over a 45-year period met the criteria; 52 underwent PM, and 23 did not. The patients undergoing PM had a median OS of 3.1 years (95% CI: 2.4, 4.7 years) with the 5- and 10-year OS being 35.5% and 32.8%, respectively. The total resected LM did not impact the OS nor the DFS. The patients who developed LM after 11 months from the initial ACC resection had an improved OS (4.2 years; 95% CI: 3.2, NR; p = 0.0096) compared to those developing metastases earlier (2.4 years; 95% CI: 1.6, 2.8). Patients who underwent PM within 11 months of adrenalectomy demonstrated a reduced OS (2.2 years; 95% CI: 1.0, 2.7) compared to those after 11 months (3.6 years, 95% CI: 2.6, NR; p = 0.0045). PM may provide benefit to those patients with LM at presentation (HR: 0.5; p = 0.2827), with the time to first PM as a time-varying covariate.

CONCLUSIONS

PM appears to have a role in ACC patients. The number of nodules should not be an exclusion factor. Patients developing LM within a year of primary tumor resection may benefit from waiting before further surgeries, which may provide additional insight into who may benefit from PM.

Clinical utility of immunohistochemical subtyping in patients with small cell lung cancer

OBJECTIVES

Molecular subtyping of small cell lung cancer (SCLC) tumors based on the expression of four transcription factors (ASCL1, NEUROD1, POU2F3, and YAP1) using immunohistochemical (IHC) staining has recently emerged as a proposed approach. This study was aimed to examine this subtyping method in Asian patients with SCLC and investigate its correlation with treatment efficacy.

MATERIALS AND METHODS

Seventy-two tumor samples from patients with SCLC, including de novo cases and those transformed from EGFR-mutant tumors, were analyzed. IHC staining was used to measure the expression of the four transcription factors and conventional SCLC markers. Subtypes were defined based on relative expression levels. The treatment response and outcome of patients receiving immune checkpoint inhibitors and chemotherapy were also reviewed.

RESULTS

ASCL1 was the most common subtype, observed in 55.2 % of the samples, followed by NEUROD1 (26.9 %) and POU2F3 (9 %). No tumor exhibited predominant YAP1 positivity, while 41.8 % of the samples demonstrated positivity for two subtype markers. Approximately 50 % of the patients experienced a subtype switch after disease progression. Patients with the ASCL1/NEUROD1 (SCLC-A/N) subtype had similar progression-free survival (PFS) compared to non-SCLC-A/N patients after treatment with immune checkpoint inhibitors plus chemotherapy. Transformed SCLC patients had significantly worse PFS than de novo SCLC patients after chemoimmunotherapy. (2.1 vs. 5.4 months, P = 0.023) CONCLUSIONS: This study revealed the challenges associated with using IHC alone for molecular subtyping, highlighting the frequent co-expression of subtypes and temporal changes following treatment. Further research is warranted to explore the prognostic and therapeutic implications of IHC subtyping in patients with SCLC.

Current status of National Institutes of Health funding for thoracic surgeons in the United States: Beacon of hope or candle in the wind?

OBJECTIVE

Increasing forces threaten the viability of thoracic surgeon-initiated research, a core component of our academic mission. National Institutes of Health funding is a benchmark of research productivity and innovation. This study examined the current status of National Institutes of Health funding for thoracic surgeons.

METHODS

Thoracic surgeon principal investigators on National Institutes of Health-funded grants during June 2010, June 2015, and June 2020 were identified using National Institutes of Health iSearchGrants (version 2.4). American Association of Medical Colleges data were used to identify all surgeons in the United States. Types and total costs of National Institutes of Health-funded grants were compared relative to other surgical specialties.

RESULTS

A total of 61 of 4681 (1.3%), 63 of 4484 (1.4%), and 60 of 4497 (1.3%) thoracic surgeons were principal investigators on 79, 76, and 87 National Institutes of Health-funded grants in 2010, 2015, and 2020, respectively; these rates were higher than those for most other surgical specialties (P ≤ .0001). Total National Institutes of Health costs for Thoracic Surgeon-initiated grants increased 57% from 2010 to 2020, outpacing the 33% increase in total National Institutes of Health budget. Numbers and types of grants varied among cardiovascular, transplant, and oncology subgroups. Although the majority of grants and costs were cardiovascular related, increased National Institutes of Health expenditures primarily were due to funding for transplant and oncology grants. Per-capita costs were highest for transplant-related grants during both years. Percentages of R01-to-total costs were constant at 55%. Rates and levels of funding for female versus male thoracic surgeons were comparable. Awards to 5 surgeons accounted for 33% of National Institutes of Health costs for thoracic surgeon principal investigators in 2020; a similar phenomenon was observed for 2010 and 2015.

CONCLUSIONS

Long-term structural changes must be implemented to more effectively nurture the next generation of thoracic surgeon scientists.

Targeting FAcilitates Chromatin Transcription complex inhibits pleural mesothelioma and enhances immunotherapy

BACKGROUND

Diffuse pleural mesothelioma (DPM) is an aggressive therapy-resistant cancer with unique molecular features. Numerous agents have been tested, but clinically effective ones remain elusive. Herein, we propose to use a small molecule CBL0137 (curaxin) that simultaneously suppresses nuclear factor-κB (NF-κB) and activates tumor suppressor p53 via targeting FAcilitates Chromatin Transcription (FACT) complex, a histone chaperone critical for DNA repair.

METHODS

We used DPM cell lines, murine models (xeno- and allo-grafts), plus DPM patient samples to characterize anti-tumor effects of CBL0137 and to delineate specific molecular mechanisms.

RESULTS

We verified that CBL0137 induced cell cycle arrest and apoptosis. We also discovered that DPM is a FACT-dependent cancer with overexpression of both subunits structure-specific recognition protein 1 (SSRP1), a poor prognosis indicator, and suppressor of Ty 16 (SUPT16H). We defined several novel uses of CBL0137 in DPM therapy. In combination with cisplatin, CBL0137 exhibited additive anti-tumor activity compared to monotherapy. Similarly, CBL0137 (systemic) could be combined with other novel agents like microRNA-215 (intrapleural) as a more effective regimen. Importantly, we established that CBL0137 induces immunogenic cell death that contributes to activating immune response pathways in DPM. Therefore, when CBL0137 is combined with dual immune checkpoint inhibitors DPM tumor growth is significantly suppressed.

CONCLUSIONS

We identified an unrecognized molecular vulnerability of DPM based on FACT dependency. CBL0137 alone and in several combinations with different therapeutics showed promising efficacy, including that of improved anti-tumor immunity. Overall, these preclinical findings suggest that CBL0137 could be ideally suited for use in DPM clinical trials.

Neuroendocrine lineage commitment of small cell lung cancers can be leveraged into p53-independent non-cytotoxic therapy

Small cell lung cancers (SCLCs) rapidly resist cytotoxic chemotherapy and immune checkpoint inhibitor (ICI) treatments. New, non-cross-resistant therapies are thus needed. SCLC cells are committed into neuroendocrine lineage then maturation arrested. Implicating DNA methyltransferase 1 (DNMT1) in the maturation arrests, we find (1) the repression mark methylated CpG, written by DNMT1, is retained at suppressed neuroendocrine-lineage genes, even as other repression marks are erased; (2) DNMT1 is recurrently amplified, whereas Ten-Eleven-Translocation 2 (TET2), which functionally opposes DNMT1, is deleted; (3) DNMT1 is recruited into neuroendocrine-lineage master transcription factor (ASCL1, NEUROD1) hubs in SCLC cells; and (4) DNMT1 knockdown activated ASCL1-target genes and released SCLC cell-cycling exits by terminal lineage maturation, which are cycling exits that do not require the p53/apoptosis pathway used by cytotoxic chemotherapy. Inhibiting DNMT1/corepressors with clinical compounds accordingly extended survival of mice with chemorefractory and ICI-refractory, p53-null, disseminated SCLC. Lineage commitment of SCLC cells can hence be leveraged into non-cytotoxic therapy able to treat chemo/ICI-refractory SCLC.

A Unique Gene Signature Predicting Recurrence Free Survival in Stage IA Lung Adenocarcinoma

Objective

Resected stage IA lung adenocarcinoma (LUAD) has a reported 5-year recurrence free survival (RFS) of 63-81%. A unique gene signature stratifying patients with early stage LUAD as high or low-risk of recurrence would be valuable.

Methods

GEO datasets combining European and North American LUAD patients (n=684) were filtered for stage IA (n=105) to develop a robust signature for recurrence (RFSscore). Univariate Cox proportional hazard regression model was used to assess associations of gene expression with RFS and OS. Leveraging a bootstrap approach of these identified upregulated genes allowed construction of a model which was evaluated by Area Under the Received Operating Characteristics. The optimal signature has RFSscore calculated via a linear combination of expression of selected genes weighted by the corresponding Cox regression derived coefficients. Log-rank analysis calculated RFS and OS. Results were validated using the LUAD TCGA transcriptomic NGS based dataset.

Results

Rigorous bioinformatic analysis identified a signature of 4 genes: KNSTRN, PAFAH1B3, MIF, CHEK1. Kaplan-Meier analysis of stage IA LUAD with this signature resulted in 5-year RFS for low-risk of 90% compared to 53% for high-risk (HR 6.55, 95%CI 2.65-16.18, p-value <0.001), confirming the robustness of the gene signature with its clinical significance. Validation of the signature using TCGA dataset resulted in an AUC of 0.797 and 5-year RFS for low and high-risk stage IA patients being 91% and 67%, respectively (HR 3.44, 95%CI 1.16-10.23, p-value=0.044).

Conclusions

This 4 gene signature stratifies European and North American patients with pathologically confirmed stage IA LUAD into low and high-risk groups for OS and more importantly RFS.

Cigarette Smoke Enhances the Malignant Phenotype of Esophageal Adenocarcinoma Cells by Disrupting a Repressive Regulatory Interaction Between miR-145 and LOXL2

Although linked to esophageal carcinogenesis, the mechanisms by which cigarette smoke mediates initiation and progression of esophageal adenocarcinomas (EAC) have not been fully elucidated. In this study, immortalized esophageal epithelial cells and EAC cells (EACCs) were cultured with or without cigarette smoke condensate (CSC) under relevant exposure conditions. Endogenous levels of microRNA (miR)-145 and lysyl-likeoxidase 2 (LOXL2) were inversely correlated in EAC lines/tumors compared with that in immortalized cells/normal mucosa. The CSC repressed miR-145 and upregulated LOXL2 in immortalized esophageal epithelial cells and EACCs. Knockdown or constitutive overexpression of miR-145 activated or depleted LOXL2, respectively, which enhanced or reduced proliferation, invasion, and tumorigenicity of EACC, respectively. LOXL2 was identified as a novel target of miR-145 as well as a negative regulator of this miR in EAC lines/Barrett's epithelia. Mechanistically, CSC induced recruitment of SP1 to the LOXL2 promoter; LOXL2 upregulation coincided with LOXL2 enrichment and concomitant reduction of H3K4me3 levels within the promoter of miR143HG (host gene for miR-145). Mithramycin downregulated LOXL2 and restored miR-145 expression in EACC and abrogated LOXL2-mediated repression of miR-145 by CSC. These findings implicate cigarette smoke in the pathogenesis of EAC and demonstrate that oncogenic miR-145-LOXL2 axis dysregulation is potentially druggable for the treatment and possible prevention of these malignancies.

mTOR inhibition overcomes RSK3-mediated resistance to BET inhibitors in small cell lung cancer

Small cell lung cancer (SCLC) is a recalcitrant malignancy with limited treatment options. Bromodomain and extraterminal domain inhibitors (BETis) have shown promising preclinical activity in SCLC, but the broad sensitivity spectrum limits their clinical prospects. Here, we performed unbiased high-throughput drug combination screens to identify therapeutics that could augment the antitumor activities of BETis in SCLC. We found that multiple drugs targeting the PI-3K-AKT-mTOR pathway synergize with BETis, among which mTOR inhibitors (mTORis) show the highest synergy. Using various molecular subtypes of the xenograft models derived from patients with SCLC, we confirmed that mTOR inhibition potentiates the antitumor activities of BETis in vivo without substantially increasing toxicity. Furthermore, BETis induce apoptosis in both in vitro and in vivo SCLC models, and this antitumor effect is further amplified by combining mTOR inhibition. Mechanistically, BETis induce apoptosis in SCLC by activating the intrinsic apoptotic pathway. However, BET inhibition leads to RSK3 upregulation, which promotes survival by activating the TSC2-mTOR-p70S6K1-BAD cascade. mTORis block this protective signaling and augment the apoptosis induced by BET inhibition. Our findings reveal a critical role of RSK3 induction in tumor survival upon BET inhibition and warrant further evaluation of the combination of mTORis and BETis in patients with SCLC.

CD70 and PD-L1 (CD274) co-expression predicts poor clinical outcomes in patients with pleural mesothelioma

Diffuse pleural mesothelioma (PM) is a highly aggressive tumour typically associated with short survival. Recently, the effectiveness of first-line immune checkpoint inhibitors in patients with unresectable PM was reported. CD70-CD27 signalling plays a co-stimulatory role in promoting T cell expansion and differentiation through the nuclear factor κB (NF-κB) pathway. Conversely, the PD-L1 (CD274)-PD-1 (PDCD1) pathway is crucial for the modulation of immune responses in normal conditions. Nevertheless, pathological activation of both the CD70-CD27 and PD-L1-PD-1 pathways by aberrantly expressed CD70 and PD-L1 participates in the immune evasion of tumour cells. In this study, 171 well-characterised PMs including epithelioid (n = 144), biphasic (n = 15), and sarcomatoid (n = 12) histotypes were evaluated immunohistochemically for CD70, PD-L1, and immune cell markers such as CD3, CD4, CD8, CD56, PD-1, FOXP3, CD68, and CD163. Eight percent (14/171) of mesotheliomas simultaneously expressed CD70 and PD-L1 on the tumour cell membrane. PMs co-expressing CD70 and PD-L1 contained significantly higher numbers of CD8+ (p = 0.0016), FOXP3+ (p = 0.00075), and CD163+ (p = 0.0011) immune cells within their microenvironments. Overall survival was significantly decreased in the cohort of patients with PM co-expressing CD70 and PD-L1 (p < 0.0001). In vitro experiments revealed that PD-L1 and CD70 additively enhanced the motility and invasiveness of PM cells. In contrast, PM cell proliferation was suppressed by PD-L1. PD-L1 enhanced mesenchymal phenotypes such as N-cadherin up-regulation. Collectively, these findings suggest that CD70 and PD-L1 both enhance the malignant phenotypes of PM and diminish anti-tumour immune responses. Based on our observations, combination therapy targeting these signalling pathways might be useful in patients with PM.

BET Inhibitors Target the SCLC-N Subtype of Small-Cell Lung Cancer by Blocking NEUROD1 Transactivation

Small-cell lung cancer (SCLC) is a recalcitrant malignancy that urgently needs new therapies. Four master transcription factors (ASCL1, NEUROD1, POU2F3, and YAP1) have been identified in SCLC, and each defines the transcriptome landscape of one molecular subtype. However, these master transcription factors have not been found directly druggable. We hypothesized that blocking their transcriptional coactivator(s) could provide an alternative approach to target these master transcription factors. Here, we identify that BET proteins physically interact with NEUROD1 and function as transcriptional coactivators. Using CRISPR knockout and ChIP-seq, we demonstrate that NEUROD1 plays a critical role in defining the landscapes of BET proteins in the SCLC genome. Blocking BET proteins by inhibitors led to broad suppression of the NEUROD1-target genes, especially those associated with superenhancers, resulting in the inhibition of SCLC growth in vitro and in vivo. LSAMP, a membrane protein in the IgLON family, was identified as one of the NEUROD1-target genes mediating BET inhibitor sensitivity in SCLC. Altogether, our study reveals that BET proteins are essential in regulating NEUROD1 transactivation and are promising targets in SCLC-N subtype tumors.

IMPLICATIONS

Our findings suggest that targeting transcriptional coactivators could be a novel approach to blocking the master transcription factors in SCLC for therapeutic purposes.

Targeting mutant p53-R248W reactivates WT p53 function and alters the onco-metabolic profile

TP53 is the most commonly mutated gene in cancer, and gain-of-function mutations have wide-ranging effects. Efforts to reactivate wild-type p53 function and inhibit mutant functions have been complicated by the variety of TP53 mutations. Identified from a screen, the NSC59984 compound has been shown to restore activity to mutant p53 in colorectal cancer cells. Here, we investigated its effects on esophageal adenocarcinoma cells with specific p53 hot-spot mutations. NSC59984 treatment of cells reactivated p53 transcriptional regulation, inducing mitochondrial intrinsic apoptosis. Analysis of its effects on cellular metabolism demonstrated increased utilization of the pentose phosphate pathway and inhibition of glycolysis at the fructose-1,6-bisphosphate to fructose 6-phosphate junction. Furthermore, treatment of cells with NSC59984 increased reactive oxygen species production and decreased glutathione levels; these effects were enhanced by the addition of buthionine sulfoximine and inhibited by N-acetyl cysteine. We found that the effects of NSC59984 were substantially greater in cells harboring the p53 R248W mutation. Overall, these findings demonstrate p53-dependent effects of NSC59984 on cellular metabolism, with increased activity in cells harboring the p53 R248W mutation. This research highlights the importance of defining the mutational status of a particular cancer to create a patient-centric strategy for the treatment of p53-driven cancers.

Abstract A013: Induced pluripotent stem cells derived from normal human esophageal epithelial cells identify transcription factor networks contributing to esophageal carcinogenesis

Esophageal cancer (EsC) is the sixth leading cause of cancer-related mortality worldwide. Esophageal squamous cell cancers (ESCC) typically arise in the upper and mid-esophagus, whereas esophageal adenocarcinomas (EAC) arise in the distal esophagus and gastroesophageal junction. Presently, epigenetic mechanisms contributing to initiation, progression, and dissemination of EsC have not been fully elucidated. The present study was undertaken to determine if induced pluripotent stem cells (iPSCs) derived from normal esophageal epithelial cells (Eso-iPSCs), EsC cell lines cultured in stemness enriched conditions, and cancer stem-like cells isolated from primary EsC specimens could be used to identify unique primitive stem-like transcription factor networks associated with epigenetic plasticity, chemoresistance, and metastatic potential of EsC cells. RNA-seq analysis demonstrated that genes differentially expressed in Eso-iPSC overlapped with transcriptome signatures in lung-iPSC (Lu-iPSC) which we previously generated to identify novel therapeutic targets in lung cancers; similar to Lu-iPSC, Eso-iPSC transcriptome signatures overlapped considerably more with small cell lung cancers (SCLC) compared to non-small cell lung cancers (NSCLC), possibly reflecting greater stemness in SCLC. We next compared transcriptome signatures of Eso-iPSC with stem-like-EAC enrichment models (cell lines and PDX). 6% and 8% of differentially expressed genes in Eso-iPSC uniquely overlapped with EAC or ESCC lines, respectively, whereas 24% were common to Eso-iPSC, EAC cells, and ESCC cells. Culturing of EAC cells on matrigel or propagation of EAC as primary patient derived xenografts increased commonalities of Eso-iPSC and EAC transcriptome signatures. Lastly, we compared transcriptomes of Eso-iPSC with Barrett’s esophagus (BE; a premalignant condition in which the squamous epithelium of the distal esophagus is replaced by metaplastic columnar epithelial cells) and EAC samples. By combining and stringently filtering transcriptome, ATAC-seq, DNA methylome, and ChIP-seq datasets for tissue- and disease-specific signatures, we identified several potentially druggable, master TFs mediating stemness/plasticity, chemoresistance, and metastatic potential which are shared between EsC lines and primary tumor specimens. Enrichment techniques promoted acquisition of more stem-like states in cultured EAC cells as reflected in multi-omic signatures of these cells relative to Eso-iPSC and primary EAC specimens. Collectively, these findings establish proof of principal for our experimental approach which is now being used to further characterize epigenetic mechanisms contributing to esophageal carcinogenesis and to identify novel targets for EsC therapy.

Citation Format: Haitao Wang, Ruihong Wang, Katherine P. Prothro, Sichuan Xi, Weilong Hou, Xinwei Wu, Tuana Tolunay, Vivek Shukla, Mary R. Zhang, Stephanie J. Shiffka, Sudheer Gara, David S. Schrump. Induced pluripotent stem cells derived from normal human esophageal epithelial cells identify transcription factor networks contributing to esophageal carcinogenesis. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Epigenomics; 2022 Oct 6-8; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_2):Abstract nr A013.

Smoking-associated Downregulation of FILIP1L Enhances Lung Adenocarcinoma Progression Through Mucin Production, Inflammation, and Fibrosis

Lung adenocarcinoma (LUAD) is the major subtype in lung cancer, and cigarette smoking is essentially linked to its pathogenesis. We show that downregulation of Filamin A interacting protein 1-like (FILIP1L) is a driver of LUAD progression. Cigarette smoking causes its downregulation by promoter methylation in LUAD. Loss of FILIP1L increases xenograft growth, and, in lung-specific knockout mice, induces lung adenoma formation and mucin secretion. In syngeneic allograft tumors, reduction of FILIP1L and subsequent increase in its binding partner, prefoldin 1 (PFDN1) increases mucin secretion, proliferation, inflammation, and fibrosis. Importantly, from the RNA-sequencing analysis of these tumors, reduction of FILIP1L is associated with upregulated Wnt/β-catenin signaling, which has been implicated in proliferation of cancer cells as well as inflammation and fibrosis within the tumor microenvironment. Overall, these findings suggest that down-regulation of FILIP1L is clinically relevant in LUAD, and warrant further efforts to evaluate pharmacologic regimens that either directly or indirectly restore FILIP1L-mediated gene regulation for the treatment of these neoplasms.

Significance

This study identifies FILIP1L as a tumor suppressor in LUADs and demonstrates that downregulation of FILIP1L is a clinically relevant event in the pathogenesis and clinical course of these neoplasms.

Definition of a new blood cell count score for early survival prediction for non-small cell lung cancer patients treated with atezolizumab: Integrated analysis of four multicenter clinical trials

Importance

Blood cell count test (BCT) is a robust method that provides direct quantification of various types of immune cells to reveal the immune landscape to predict atezolizumab treatment outcomes for clinicians to decide the next phase of treatment.

Objective

This study aims to define a new BCTscore model to predict atezolizumab treatment benefits in non-small lung cell cancer (NSCLC) patients.

Design, Setting, and Participants

This study analyzed four international, multicenter clinical trials (OAK, BIRCH, POPLAR, and FIR trials) to conduct post-hoc analyses of NSCLC patients undergoing atezolizumab (anti–PD-L1) single-agent treatment (n = 1,479) or docetaxel single-agent treatment (n = 707). BCT was conducted at three time points: pre-treatment (T1), the first day of treatment cycle 3 (T2), and first day of treatment cycle 5 (T3). Univariate and multivariate Cox regression analyses were conducted to identify early BCT biomarkers to predict atezolizumab treatment outcomes in NSCLC patients.

Main Outcomes and Measures

Overall survival (OS) was used as the primary end point, whereas progression-free survival (PFS) according to Response Evaluation Criteria in Solid Tumors (RECIST), clinical benefit (CB), and objective response rate (ORR) were used as secondary end points.

Results

The BCT biomarkers of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) at time point T3 and neutrophil-to-monocyte ratio (NMR) at time point T2 with absolute cutoff values of NLR_T3 = 5, PLR_T3 = 180, and NMR_T2 = 6 were identified as strong predictive biomarkers for atezolizumab (Ate)–treated NSCLC patients in comparison with docetaxel (Dtx)–treated patients regarding OS (BCTscore low risk: HR _Ate vs_{. Dtx} = 1.54 (95% CI: 1.04–2.27), P = 0.031; high risk: HR _Ate vs_{. Dtx} = 0.84 (95% CI: 0.62–1.12), P = 0.235). The identified BCTscore model showed better OS AUC in the OAK (AUC_12month = 0.696), BIRCH (AUC_12month = 0.672) and POPLAR+FIR studies (AUC_12month = 0.727) than that of each of the three single BCT biomarkers.

Conclusion and Relevance

The BCTscore model is a valid predictive and prognostic biomarker for early survival prediction in atezolizumab-treated NSCLC patients.

Spatial meta-transcriptomics reveal associations of intratumor bacteria burden with lung cancer cells showing a distinct oncogenic signature

BACKGROUND

The lung intratumor microbiome influences lung cancer tumorigenesis and treatment responses, but detailed data on the extent, location, and effects of microbes within lung tumors are missing, information needed for improved prognosis and treatment.

METHODS

To address this gap, we developed a novel spatial meta-transcriptomic method simultaneously detecting the expression level of 1,811 host genes and 3 microbe targets (bacteria, fungi, and cytomegalovirus). After rigorous validation, we analyzed the spatial meta-transcriptomic profiles of tumor cells, T cells, macrophages, other immune cells, and stroma in surgically resected tumor samples from 12 patients with early-stage lung cancer.

RESULTS

Bacterial burden was significantly higher in tumor cells compared with T cells, macrophages, other immune cells, and stroma. This burden increased from tumor-adjacent normal lung and tertiary lymphoid structures to tumor cells to the airways, suggesting that lung intratumor bacteria derive from the latter route of entry. Expression of oncogenic β-catenin was strongly correlated with bacterial burden, as were tumor histological subtypes and environmental factors.

CONCLUSIONS

Intratumor bacteria were enriched with tumor cells and associated with multiple oncogenic pathways, supporting a rationale for reducing the local intratumor microbiome in lung cancer for patient benefit.

TRIAL REGISTRATION NUMBER

NCT00242723, NCT02146170.

Abstract 5470: Inhibition of facilitates chromatin transcription complex attenuates mesothelioma growth

Introduction: Malignant pleural mesothelioma (MPM) is an aggressive incurable cancer usually associated with asbestos exposure. MPM has unique molecular features such as wild-type p53 (&gt;90% regardless of histology) and aberrantly activated NF-κB. A diverse spectrum of anti-MPM therapeutic agents have been trialed, but clinically effective ones remain elusive. Herein, we propose to use a novel small molecule (CBL0137) that simultaneously suppresses NF-κB and activates tumor suppressor p53 via targeting FAcilitates Chromatin Transcription (FACT) complex, a histone chaperone critical for DNA repair in cancers.

Methods: We employed in-silico, in-vitro and in-vivo MPM models and patient tumor specimens to characterize CBL0137 efficacy in MPM. CBL0137 effects were assessed in a panel of MPM cell lines by proliferation, colony foci formation, flow cytometry, and cell cycle assays. Drug-specific mechanisms were verified at transcript and protein levels using appropriate molecular assays. Both monotherapy and combinatorial regimens were tested to evaluate the optimal deployment of CBL0137 in comparison to several controls including standard chemotherapy. Immunodeficient (NSG) mice with subcutaneous and orthotopic MPM tumor grafts were used to evaluate the anti-tumor efficacy of CBL0137. Kaplan-Meier and log-rank test were applied for survival outcomes.

Results: We observed that transcript and protein levels of SSRP1 and SPT16, subunits of the FACT complex, were significantly upregulated in our collection of MPM cell lines and specimens compared to normal. The TCGA database revealed that overexpression of these FACT subunits was associated with poor survival. As determined by western blot and luciferase-reporter assay, CBL0137 simultaneously inhibited NF-κB and activated p53 in MPM cells. CBL0137 treatment significantly (p&lt;0.05) suppressed MPM cells proliferation, invasiveness, colony foci formation, and increased the number of apoptotic cells. Interestingly, in combination with cisplatin, CBL0137 exhibited additive anti-tumor activity in much lower dose ranges compared to monotherapy. Additionally, CBL0137 synergized with different classes of agents like microRNA-215, which triggers activation of p53 via regulation of MDM2 at transcript level. In vivo, CBL0137 treatment significantly suppressed MPM tumor growth in subcutaneous and orthotopic xenograft models compared to control. Kaplan-Meier analysis showed that CBL0137 treatment improved overall survival.

Conclusions: MPM is dependent on FACT for tumor progression since higher levels of SSRP1 and SPT16 are associated with worse prognosis. This MPM vulnerability can be leveraged to identify novel therapeutic paradigms. Targeting this MPM dependency by CBL0137 (dual effects on NF-κB and p53) alone or in various combinations with different classes of drugs holds great promise for improved outcomes regardless of histotype.

Citation Format: Anand Singh, Nathanael Pruett, Roma Pahwa, Sudheer K. Gara, Shivani Dixit, Agnes Choi, David S. Schrump, Chuong D. Hoang. Inhibition of facilitates chromatin transcription complex attenuates mesothelioma growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5470.

Spatial meta-transcriptomics reveal intratumor bacterial association with lung cancer cells showing a distinct oncogenic signature

8531

Background: The lung intratumor microbiome influences lung cancer tumorigenesis and treatment responses, but detailed data on the extent, location, and effects of microbes within lung tumors is missing, information needed to improve treatment outcomes and prognosis. Methods: To address this gap, we developed a novel spatial meta-transcriptomic method simultaneously detecting the expression level of 1,811 host genes and three microbe targets (16S rRNA, 28S rRNA and CMV). After rigorous validation, we analyzed the spatial meta-transcriptomic profiles of tumor cells, T cells, macrophages, other immune cells, and stroma in tumor samples from 12 patients with early-stage lung cancer. Results: Bacterial burden was significantly higher in tumor cells compared to T cells, macrophages, other immune cells, and stroma. This burden increased from tumor-adjacent normal lung and tertiary lymphoid structures to tumor cells to the airways, suggesting that lung intratumor bacteria derive from the latter route of entry. Expression of oncogenic β-catenin and epithelial-mesenchymal transition pathway genes was strongly correlated with bacterial burden, as were tumor subtypes, mutation profile, histology and smoking history. Conclusions: Intratumor bacteria were enriched with tumor cells and associated with multiple oncogenic pathways, supporting a rationale for reducing the local intratumor microbiome in lung cancer to optimize clinical outcomes. This research was supported in part by the Intramural Research Programs of the NCI and NIAID. Other funding sources included ASCO Young Investigator Award, SITC-AstraZeneca Immunotherapy in Lung Cancer (Early Stage NSCLC) Clinical Fellowship Award, NIH Bench-to-Bedside and Back Program (BtB), NCI R00 award (CA226400), Emerson Collective Cancer Research fund, Lung Cancer Research Foundation (LCRF) pilot grant and W.W. Smith Trust Foundation award. This study was approved by NCI institutional review board (NCT00242723 and NCT02146170) and Animal Use and Care Committee at the University of Pennsylvania (#806875).

Development and validation of longitudinal c-reactive protein as dynamic response predictor for PD-L1 blockade in advanced NSCLC: Findings from four atezolizumab clinical trials

e21113

Background: Numerous studies suggested that pre-treatment C-reactive protein (CRP) is a survival predictive biomarker for cancer patients treated with anti-PD-(L)1 blockade. However, the application of longitudinal CRP levels as dynamic biomarker for advanced non-small cell lung cancer (NSCLC) patients treated with anti-PD-(L)1 remains unexplored. Methods: This study analyzed four international, multi-center clinical trials (OAK, BIRCH, POPLAR and FIR trials) to conduct post-hoc analyses of NSCLC patients undergoing atezolizumab (anti-PD-L1) single-agent treatment. CRP test was performed ≤ 96 hours before Day 1 of each cycle. 1438 patients with more than 2 times CRP results (a total of 11,253 records) in all 3 collection timepoints. The primary endpoint was overall survival (OS). First, multivariate survival analysis was conducted to include clinical factors such as gender, ECOG-PS, race and metastases as contributing risk factors. Then, multivariate joint modelling of longitudinal and time-to-event data was used to establish the relationship between longitudinal CRP and OS in the OAK study, whereas external validation was performed by time-dependent AUC analysis on the BIRCH, POPLAR and FIR studies. Results: Log-transformed longitudinal CRP levels (log(CRP)) in combination with clinical factors in absence of PD-L1 expression emerged as independent predictors of worse OS in the OAK study (HR of jointed model = 2.08, 95% CI: 1.84-2.35, p < 0.001) with a high accuracy (AUC = 0.74) for predicting OS. The predictive value of longitudinal CRP was validated in the external validation cohorts with good performance in OS (BIRCH: HR = 2.77 (95% CI: 2.31-3.44), AUC = 0.76; POPLAR: HR = 1.95 (95% CI: 1.50-2.64), AUC = 0.76; and FIR: HR = 1.83 (95% CI: 1.46 -2.39), AUC = 0.72). Conclusions: The Bayesian multivariate joint model demonstrated that longitudinal CRP is a strong survival dynamic predictor for atezolizumab-treated NSCLC patients.

Molecular Subtypes of Primary SCLC Tumors and Their Associations With Neuroendocrine and Therapeutic Markers

INTRODUCTION

A new molecular subtype classification was recently proposed for SCLC. It is necessary to validate it in primary SCLC tumors by immunohistochemical (IHC) staining and define its clinical relevance.

METHODS

We used IHC to assess four subtype markers (ASCL1, NEUROD1, POU2F3, and YAP1) in 194 cores from 146 primary SCLC tumors. The profiles of tumor-associated CD3+ and CD8+ T-cells, MYC paralogs, SLFN11, and SYP were compared among different subtypes. Validation was performed using publicly available RNA sequencing data of SCLC.

RESULTS

ASCL1, NEUROD1, POU2F3, and YAP1 were the dominant molecular subtypes in 78.2%, 5.6%, 7%, and 2.8% of the tumors, respectively; 6.3% of the tumors were negative for all four subtype markers. Notably, three cases were uniquely positive for YAP1. Substantial intratumoral heterogeneity was observed, with 17.6% and 2.8% of the tumors being positive for two and three subtype markers, respectively. The non-ASCL1/NEUROD1 tumors had more CD8+ T-cells and manifested more frequently an "inflamed" immunophenotype. L-MYC and MYC were more often associated with ASCL1/NEUROD1 subtypes and non-ASCL1/NEUROD1 subtypes, respectively. SLFN11 expression was absent in 40% of the tumors, especially those negative for the four subtype markers. SYP was often expressed in the ASCL1 and NEUROD1 subtypes and was associated with less tumor-associated CD8+ T-cells and a "desert" immunophenotype.

CONCLUSIONS

We validated the new molecular subtype classification in primary SCLC tumors by IHC and identified several intriguing associations between subtypes and therapeutic markers. The new subtype classification may potentially assist treatment decisions in SCLC.

Hookah Smoke Mediates Cancer-Associated Epigenomic and Transcriptomic Signatures in Human Respiratory Epithelial Cells

Introduction

Although communal smoking of hookah by means of water pipes is perceived to be a safe alternative to cigarette smoking, the effects of hookah smoke in respiratory epithelia have not been well characterized. This study evaluated epigenomic and transcriptomic effects of hookah smoke relative to cigarette smoke in human respiratory epithelial cells.

Methods

Primary normal human small airway epithelial cells from three donors and cdk4 and hTERT-immortalized small airway epithelial cells and human bronchial epithelial cells were cultured for 5 days in normal media with or without cigarette smoke condensates (CSCs) or water pipe condensates (WPCs). Cell count, immunoblot, RNA sequencing, quantitative real-time reverse-transcriptase polymerase chain reaction, methylation-specific polymerase chain reaction, and quantitative chromatin immunoprecipitation techniques were used to compare effects of hookah and cigarette smoke on cell proliferation, global histone marks, gene expression, and promoter-related chromatin structure.

Results

CSC and WPC decreased global H4K16ac and H4K20me3 histone marks and mediated distinct and overlapping cancer-associated transcriptome signatures and pathway modulations that were cell line dependent and stratified across lung cancer cells in a histology-specific manner. Epiregulin encoding a master regulator of EGFR signaling that is overexpressed in lung cancers was up-regulated, whereas FILIP1L and ABI3BP encoding mediators of senescence that are repressed in lung cancers were down-regulated by CSC and WPC. Induction of epiregulin and repression of FILIP1L and ABI3BP by these condensates coincided with unique epigenetic alterations within the respective promoters.

Conclusions

These findings support translational studies to ascertain if hookah-mediated epigenomic and transcriptomic alterations in cultured respiratory epithelia are detectable and clinically relevant in hookah smokers.

Two distinct classes of thymic tumors in patients with MEN1 show LOH at the MEN1 locus

Patients with the multiple endocrine neoplasia type 1 (MEN1) syndrome carry germline heterozygous loss-of-function mutations in the MEN1 gene which predisposes them to develop various endocrine and non-endocrine tumors. Over 90% of the tumors show loss of heterozygosity (LOH) at chromosome 11q13, the MEN1 locus, due to somatic loss of the wild-type MEN1 allele. Thymic neuroendocrine tumors (NETs) or thymic carcinoids are uncommon in MEN1 patients but are a major cause of mortality. LOH at the MEN1 locus has not been demonstrated in thymic tumors. The goal of this study was to investigate the molecular aspects of MEN1-associated thymic tumors including LOH at the MEN1 locus and RNA-sequencing (RNA-Seq) to identify genes associated with tumor development and potential targeted therapy. A retrospective chart review of 294 patients with MEN1 germline mutations identified 14 patients (4.8%) with thymic tumors (12 thymic NETs and 2 thymomas). LOH at the MEN1 locus was identified in 10 tumors including the 2 thymomas, demonstrating that somatic LOH at the MEN1 locus is also the mechanism for thymic tumor development. Unsupervised principal component analysis and hierarchical clustering of RNA-Seq data showed that thymic NETs formed a homogenous transcriptomic group separate from thymoma and normal thymus. KSR2 (kinase suppressor of Ras 2), that promotes Ras-mediated signaling, was abundantly expressed in thymic NETs, a potential therapeutic target. The molecular insights gained from our study about thymic tumors combined with similar data from other MEN1-associated tumors may lead to better surveillance and treatment of these rare tumors.

Sirt1 deficiency upregulates glutathione metabolism to prevent hepatocellular carcinoma initiation in mice

Sirtuin-1 (SIRT1) is involved in various metabolic pathways, including fatty acid synthesis and gluconeogenesis in the liver. However, its role in initiation and progression of liver cancer remains unclear. Studying Sirt1 liver-specific knockout (LKO) mice in combination with diethylnitrosamine (DEN) treatment, we demonstrated that loss of Sirt1 rendered mice resistant to DEN-induced hepatocellular carcinoma (HCC) development. RNA-seq revealed that livers from LKO mice exhibited an enrichment in glutathione metabolism eight months after DEN challenge. Sirt1 deficiency elevated the expression of glutathione-s-transferase family genes by increasing the level of Nrf2, a key regulator of glutathione metabolism. Hence, LKO livers displayed a reductive environment with an increased ratio of GSH to GSSG and an elevated GSH level. Furthermore, using CRISPR knockout techniques, we confirmed that the impairment of HCC formation in LKO mice is mainly dependent on NRF2 signaling. Meanwhile, HCC induced by DEN could be blocked by the administration of N-acetyl cysteine (NAC) when administered one month after DEN challenge. However, NAC treatment starting five months after DEN injection was not able to prevent tumor development. In conclusion, our findings indicate that a reductive environment orchestrated by glutathione metabolism at an early stage can prevent the initiation of HCC.

Characterization of Outcomes by Surgical Management of Lung Neuroendocrine Tumors Associated With Cushing Syndrome

IMPORTANCE

Ectopic adrenocorticotropic hormone secretion from lung tumors causing Cushing syndrome are associated with high rates of morbidity. Optimal management remains obscure because knowledge is based on rare reports with few patients.

OBJECTIVE

To characterize the outcomes of lung neuroendocrine tumors associated with Cushing syndrome.

DESIGN, SETTING, AND PARTICIPANTS

An observational case series review from 1982 to 2020 was conducted in a single institution referral center. Kaplan-Meier analysis estimated disease-free survival (DFS). Participants underwent curative-intent surgery for a lung neuroendocrine tumor causing Cushing syndrome.

EXPOSURES

Lobectomy or pneumonectomy vs sublobar resection.

MAIN OUTCOMES AND MEASURES

Disease-free survival, disease persistence/recurrence.

RESULTS

Of the 68 patients, the median age was 41 years (range, 17-80 years), 42.6% (29 of 68) were male, 81.8% (54 of 66) were White, with a mean follow-up after surgery was 16 months (range, 0.1-341 months). Lobectomy was the most common procedure (48 of 68 [70.6%]), followed by wedge resection (16 of 68 [23.5%]) and segmentectomy (3 of 68 [4.4%]). Video-assisted thoracoscopic surgery was performed in 19 of 68 (27.9%) of patients. Surgical morbidity was 19.1% (13 of 68), and perioperative mortality was 1.5% (1 of 68). Lymph node positivity was 37% (22 of 59) when evaluable. The overall incidence of persistence/recurrence was 16.2% (11 of 68) with a median time to recurrence of 55 months (range, 18-152 months). The median DFS was reached in 12.7 years (0.1-334 months). There were no statistical differences in DFS based on tumor size, stage (8th edition TNM), whether full systematic lymphadenectomy was performed or not, nodal status, or surgical approach.

CONCLUSIONS AND RELEVANCE

In this case series study, neuroendocrine pulmonary tumors associated with Cushing syndrome had increased nodal metastasis, higher recurrence, and lower DFS than quiescent bronchopulmonary carcinoid tumors, but many patients experienced favorable outcomes. This observation is underscored by the discordance of TNM-stage classifications vs prognosis. Observing no difference in surgical techniques, the implication may be that a lung-sparing approach could suffice. These results may reflect the intrinsic importance of the hormone physiology instead of the carcinoid biologic factors.

Randomized phase II trial of a first-in-human cancer cell lysate vaccine in patients with thoracic malignancies

BACKGROUND

Although most malignancies express cancer-testis antigens (CTA), immune responses to these proteins are limited in thoracic oncology patients. This trial was undertaken to examine if a cancer cell lysate vaccine could induce immunity to CTA, and to ascertain if metronomic cyclophosphamide and celecoxib enhances vaccine-induced immune responses.

METHODS

Eleven patients with primary thoracic malignancies and 10 patients with extrathoracic neoplasms metastatic to the chest rendered NED by conventional therapies were randomized to receive H1299 lung cancer cell lysates (10 mg protein/vaccine) with Iscomatrix™ adjuvant via deep intradermal injection q 4 weeks ×6 with or without daily oral metronomic cyclophosphamide/celecoxib. The primary endpoint was serologic response to purified CTA assessed 1 month after the 6th vaccination. Secondary endpoints included assessment of the effects of cyclophosphamide and celecoxib on frequency and magnitude of vaccine-induced immune responses to CTA. Exploratory endpoints included evaluation of the effects of the vaccine regimens on peripheral immune subsets. Standard of care imaging studies were obtained at baseline and 1 month after the 3rd and 6th vaccinations.

RESULTS

All patients exhibited local and systemic inflammatory responses lasting 72-96 hours following vaccinations. There were no dose limiting treatment related toxicities. Fourteen patients (67%) completed all six vaccinations. Eight of 14 patients (57%) exhibited serologic responses to NY-ESO-1. One patient developed antibodies to GAGE7; several patients exhibited reactivity to XAGE and MAGE-C2. Vaccine therapy decreased the percent of Tregs (P=0.0068), PD-1 expression on Tregs (P=0.0027), PD-L1 expression on CD14+ monocytes (P=0.0089), PD-L1 expression on classical monocytes (P=0.016), and PD-L1 expression on intermediate monocytes (P=0.0031). Cyclophosphamide/celecoxib did not appear to increase immune responses or enhance vaccine-induced alterations in peripheral immune subsets.

CONCLUSIONS

H1299 lysate vaccines with Iscomatrix™ induce immune responses to CTA and modulate peripheral immune subsets in a manner that may enhance antitumor immunity in patients with thoracic malignancies.

Adenoid cystic carcinoma of the salivary gland metastasizing to the pericardium and diaphragm: Report of a rare case

BACKGROUND

Adenoid cystic carcinoma (AdCC) is an uncommon malignancy of the salivary gland characterized by slow growth, increased risk of recurrence and poor prognosis. The annual incidence in the United States is approximately 1200 cases per year and rarely involves the body cavities.

CASE PRESENTATION

We present a case of a 48-year-old male diagnosed with AdCC of the left submandibular gland. He received his last chemotherapy in 2006 and presented with pleural metastasis. After undergoing pleurectomy and decortication procedure, pericardial fluid and biopsies from the chest wall, sixth rib, diaphragm, pleural cavity and pericardium were sent for pathologic evaluation. A diagnosis of metastatic adenoid cystic carcinoma was confirmed, including in the pericardium, pericardial fluid and diaphragm.

CONCLUSION

AdCC of the submandibular gland is a malignant tumor with a high mortality rate. It is very rare for AdCC to metastasize to the pericardium and diaphragm. Metastasis to uncommon sites such as seen in our case with metastases to the pericardium and diaphragm shows the aggressive and unpredictable nature of this tumor, requiring close follow up, and indicating the need for molecular profile analysis and biomarker-stratified clinical trials.

UHRF1 Is a Novel Druggable Epigenetic Target in Malignant Pleural Mesothelioma

INTRODUCTION

Ubiquitin-like with plant homeodomain and ring finger domains 1 (UHRF1) encodes a master regulator of DNA methylation that has emerged as an epigenetic driver in human cancers. To date, no studies have evaluated UHRF1 expression in malignant pleural mesothelioma (MPM). This study was undertaken to explore the therapeutic potential of targeting UHRF1 in MPM.

METHODS

Microarray, real-time quantitative reverse transcription-polymerase chain reaction, immunoblot, and immunohistochemistry techniques were used to evaluate UHRF1 expression in normal mesothelial cells (NMCs) cultured with or without asbestos, MPM lines, normal pleura, and primary MPM specimens. The impact of UHRF1 expression on MPM patient survival was evaluated using two independent databases. RNA-sequencing, proliferation, invasion, and colony formation assays, and murine xenograft experiments were performed to evaluate gene expression and growth of MPM cells after biochemical or pharmacologic inhibition of UHRF1 expression.

RESULTS

UHRF1 expression was significantly higher in MPM lines and specimens relative to NMC and normal pleura. Asbestos induced UHRF1 expression in NMC. The overexpression of UHRF1 was associated with decreased overall survival in patients with MPM. UHRF1 knockdown reversed genomewide DNA hypomethylation, and inhibited proliferation, invasion, and clonogenicity of MPM cells, and growth of MPM xenografts. These effects were phenocopied by the repurposed chemotherapeutic agent, mithramycin. Biochemical or pharmacologic up-regulation of p53 significantly reduced UHRF1 expression in MPM cells. RNA-sequencing experiments exhibited the pleiotropic effects of UHRF1 down-regulation and identified novel, clinically relevant biomarkers of UHRF1 expression in MPM.

CONCLUSIONS

UHRF1 is an epigenetic driver in MPM. These findings support the efforts to target UHRF1 expression or activity for mesothelioma therapy.

Abstract 5328: mTOR inhibitor enhances anti-tumor effect of BET bromodomain inhibitor in small cell lung cancer

Introduction: Small cell lung cancer (SCLC) is one of the two recalcitrant cancers designated by NCI, and its 2-year survival rate has not improved over the past two decades. Novel therapy is urgently needed. BET bromodomain inhibitor (BETi), which targets transcriptional coactivator BET bromodomain proteins, has been reported to be effective in SCLC. However, given that SCLC is notorious for rapid development of drug resistance, it is necessary to identify drugs that can synergize with BETi to form a combinatorial drug regimen.

Methods: A high-throughput drug combination matrix screen was performed to identify potential agents that can synergize with BETi. Synergy between the identified candidate drugs and BETi was further validated in various SCLC cell lines by using the CellTiter-Glo assay as well as in several SCLC PDX models by examining tumor growth suppression and survival of tumor-bearing mice. Cleavage of caspase 3 and poly (ADP-ribose) polymerase (PARP) was analyzed by IHC and western blot in SCLC PDX tumors and in vitro cell lines to assess apoptosis after drug treatment, respectively.

Results: The high-throughput screen identified multiple inhibitors of the PI-3K/AKT/mTOR pathway to synergize with BETi by causing a significantly higher rate of apoptosis and cell growth inhibition. A comparison among the inhibitors that specifically target PI-3K, AKT or mTOR revealed that the combination of BETi and mTOR inhibitor (mTORi) have the highest level of synergy. The BETi/mTORi combo also showed synergy in several SCLC cell lines that are initially resistant to single agent BETi. The antitumor effect of the BETi/mTORi combinatorial treatment was further confirmed in several SCLC PDX mouse models. When compared to either single agent or vehicle, the BETi/mTORi combo treatment led to a greater degree of tumor growth suppression and a more prolonged survival of the tumor-bearing mice. This enhanced antitumor effect is connected with a significantly more apoptosis (cleaved caspase 3 or PARP) found in SCLC tumor tissues and cell lines treated with the BETi/mTORi combo.

Conclusion: mTORi can enhance the antitumor effect of BETi in SCLC by causing more apoptosis.

Citation Format: ANJU KUMARI, Lisa Gesumaria, Patricia Fetsch, Markku Miettinen, Keith Hughitt, Beverly Mock, Craig Thomas, David S. Schrump, Haobin Chen. mTOR inhibitor enhances anti-tumor effect of BET bromodomain inhibitor in small cell lung cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5328.

Normal mesothelial cell lines newly derived from human pleural biopsy explants

Mesothelial cells are arranged as a monolayer on covering membranes that invest surfaces of body cavities like the pleura and peritoneum. Primary human mesothelial cell (HMC) cultures are needed for studying mesothelial cell homeostasis and developing disease models, such as wound healing or cancers. Remarkably, there is a paucity of useable HMC lines that are currently available that faithfully recapitulate normal in vivo phenotypic characteristics. Here, we present a strategy to recover HMC from human pleural tissue and to immortalize them for extended in vitro culturing. Human pleural membrane was harvested by minimally invasive surgical techniques. HMC were isolated using a two-step process combining explant cellular outgrowth from biopsy tissue and flow cytometry based on cell surface expression of cadherin-1 and CD71. Cell cultures were generated after lentiviral transfection with human telomerase. The new HMC cultures retain the same phenotypic traits and physiologic features as their in vivo counterparts, yet they can be adapted for short-term or long-term culture in large-scale in vitro experimentation. In particular, we generated a new HMC line harboring a germline mutation in breast cancer type-1-associated protein-1 (BAP1), a causal tumor suppressor gene, that could be instrumental to malignant mesothelioma research. Patient-specific, normal HMC may serve as novel discovery tools allowing more powerful research models of both normal physiology and disease processes. Our surgically driven approach leads to a limitless resource of novel mesothelial cell cultures.

Anaplastic Lymphoma Kinase Gene Rearrangement in Children and Young Adults With Mesothelioma

INTRODUCTION

Children and young adults diagnosed with malignant mesothelioma may have unique genetic characteristics. In this study, we evaluated for the presence of the anaplastic lymphoma kinase (ALK) translocations in these patients.

METHODS

In a prospective study of mesothelioma natural history (ClinicalTrials.gov number NCT01950572), we assessed for the presence of the ALK translocation in patients younger than 40 years, irrespective of the site of disease. The presence of this translocation was assessed by means of fluorescence in situ hybridization (FISH). If the patients tested positive for the ALK translocation, both immunohistochemistry and RNA sequencing were performed on the tumor specimen.

RESULTS

Between September 2013 and December 2018, 373 patients were enrolled in the mesothelioma natural history study, of which 32 patients were 40 years old or younger at the time of their mesothelioma diagnosis. There were 25 patients with peritoneal mesothelioma, five with pleural mesothelioma, one with pericardial mesothelioma, and one with bicompartmental mesothelioma. Presence of an ALK translocation by FISH was seen in two of the 32 patients (6%) with mesothelioma. Both patients, a 14-year-old female and a 27-year-old male, had peritoneal mesothelioma and had no history of asbestos exposure, prior radiation therapy, or predisposing germline mutations. Neither had detectable ALK expression by immunohistochemistry. RNA sequencing revealed the presence of an STRN fusion partner in the female patient but failed to identify any fusion protein in the male patient.

CONCLUSIONS

Young patients with peritoneal mesothelioma should be evaluated for the presence of ALK translocations. Presence of this translocation should be assessed by FISH and these patients could potentially benefit from tyrosine kinase inhibitors targeting ALK.

CD70 expression correlates with a worse prognosis in malignant pleural mesothelioma patients via immune evasion and enhanced invasiveness

Diffuse malignant mesothelioma of the pleura (MPM) is a highly aggressive tumour that typically is associated with short survival. CD70 and CD27 belong to the tumour necrosis factor (TNF) and the TNF receptor (TNFR) superfamily, respectively. Under physiological conditions, the tightly regulated interaction between CD70 and CD27 plays a co-stimulatory role in promoting T-cell expansion and differentiation through the NFκB pathway. Aberrantly high CD70 expression has been documented in haematological and solid malignancies in association with immune evasion in malignant cells. In this study, 172 well-characterised primary diffuse MPM tumours including epithelioid (n = 145), biphasic (n = 15), and sarcomatoid (n = 12) histotypes were evaluated immunohistochemically for CD70, CD27, CD3, CD4, CD8, CD56, PDCD1 (PD-1), and FOXP3 expression. Twenty per cent (34/172) of the mesothelioma cells expressed CD70 on the cell membrane. Overall survival was significantly decreased in the cohort of patients with CD70-expressing tumour cells (p < 0.01). Patients with MPM containing a higher number of CD3⁺ (p < 0.01), CD4⁺ (p < 0.01), CD8⁺ (p < 0.01), or FOXP3⁺ (p < 0.01) tumour-infiltrating lymphoid cells (TILs) showed significantly worse clinical outcomes. As potential independent risk factors for MPM patients, multivariate Cox proportional hazards regression analysis revealed CD70 expression on mesothelioma cells [hazard ratio (HR) 2.25; p = 0.010], higher FOXP3⁺ TILs (HR 2.81; p = 0.004), and higher CD3⁺ TIL accumulation (HR 6.12; p < 0.001). In contrast, as a potential independent favourable factor, higher CD27⁺ TIL accumulation (HR 0.48; p = 0.037) was identified. In vitro experiments and an immunodeficient mouse model revealed that CD70 enhances the invasiveness of MPM cells through MET-ERK axis activation. Further analyses in syngeneic mouse models demonstrated possible roles for CD70 in immune evasion. Collectively, these findings suggest that the CD70-CD27 pathway enhances the malignant phenotypes of MPM and diminishes anti-tumor immune response in patients with these neoplasms. These markers might be useful in MPM for prognostic evaluations as well as targeted therapeutics. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Abstract 2943: Severe hepatotoxicity of mithramycin therapy caused by altering expression of hepatocellular bile transporters

Mithramycin has shown significant preclinical anticancer activity, but its therapeutic dose is limited by the development of hepatotoxicity that remains poorly characterized. A pharmacogenomics characterization of mithramycin-induced transaminitis revealed that hepatotoxicity is associated with inter-individual variation in genes involved in bile disposition: ABCB4(MDR3) rs2302387 and ABCB11(BSEP) rs4668115 variants reduce transporter expression (P&lt;0.05) and were associated with ≥Grade 3 liver function test (LFT) elevations developing 24 hours after the third infusion of mithramycin (25mcg/kg, 6hr/infusion, qdx7, every 28 days;P&lt;0.0040). A similar relationship was observed in a pediatric cohort genotyped for ABCB11. We therefore undertook to characterize the mechanism of mithramycin-induced acute transaminitis. As mithramycin affects cellular response to bile acid treatment by altering the expression of multiple bile transporters (e.g., ABCB4, ABCB11, NTCP, OSTα/β) in several cell lines (Huh7, HepaRG, HepaRG BSEP (-/-)) and primary human hepatocytes, we hypothesized that mithramycin inhibited bile-mediated activation of the farnesoid X receptor (FXR). FXR was downregulated in all hepatocyte cell lines and primary human hepatocytes (P&lt;0.0001), and mithramycin inhibited CDCA- and GW4046-induced FXR-GAL4 luciferase reporter activity (P&lt;0.001). Mithramycin promoted GCDC-induced cytotoxicity in cells lacking the BSEP transporter and increased the overall intracellular concentration of bile acids in primary human hepatocytes grown in sandwich culture (P&lt;0.01). Mithramycin is an FXR expression and FXR transactivation inhibitor that inhibits bile flow and potentiates bile-induced cellular toxicity, particularly in cells with low BSEP function. These results suggest that mithramycin causes hepatotoxicity through derangement of bile acid disposition; results also suggest that pharmacogenomic markers may be useful to identify patients who may tolerate higher mithramycin doses.

Citation Format: Tristan M. Sissung, Phoebe A. Huang, Ralph Hauke, Edel McCrea, Cody J. Peer, Roberto H. Barbier, Jonathan D. Strope, Ariel M. Ley, Mary Zhang, Julie A. Hong, David Venzon, Jonathan P. Jackson, Kenneth R. Brouwer, Patrick Grohar, John Glod, Brigitte C. Widemann, Theo Heller, David S. Schrump, William D. Figg. Severe hepatotoxicity of mithramycin therapy caused by altering expression of hepatocellular bile transporters [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2943.

Severe Hepatotoxicity of Mithramycin Therapy Caused by Altered Expression of Hepatocellular Bile Transporters

Mithramycin demonstrates preclinical anticancer activity, but its therapeutic dose is limited by the development of hepatotoxicity that remains poorly characterized. A pharmacogenomics characterization of mithramycin-induced transaminitis revealed that hepatotoxicity is associated with germline variants in genes involved in bile disposition: ABCB4 (multidrug resistance 3) rs2302387 and ABCB11 [bile salt export pump (BSEP)] rs4668115 reduce transporter expression (P < 0.05) and were associated with ≥grade 3 transaminitis developing 24 hours after the third infusion of mithramycin (25 mcg/kg, 6 hours/infusion, every day ×7, every 28 days; P < 0.0040). A similar relationship was observed in a pediatric cohort. We therefore undertook to characterize the mechanism of mithramycin-induced acute transaminitis. As mithramycin affects cellular response to bile acid treatment by altering the expression of multiple bile transporters (e.g., ABCB4, ABCB11, sodium/taurocholate cotransporting polypeptide, organic solute transporter α/β) in several cell lines [Huh7, HepaRG, HepaRG BSEP (-/-)] and primary human hepatocytes, we hypothesized that mithramycin inhibited bile-mediated activation of the farnesoid X receptor (FXR). FXR was downregulated in all hepatocyte cell lines and primary human hepatocytes (P < 0.0001), and mithramycin inhibited chenodeoxycholic acid- and GW4046-induced FXR-galactose-induced gene 4 luciferase reporter activity (P < 0.001). Mithramycin promoted glycochenodeoxycholic acid-induced cytotoxicity in ABCB11 (-/-) cells and increased the overall intracellular concentration of bile acids in primary human hepatocytes grown in sandwich culture (P < 0.01). Mithramycin is a FXR expression and FXR transactivation inhibitor that inhibits bile flow and potentiates bile-induced cellular toxicity, particularly in cells with low ABCB11 function. These results suggest that mithramycin causes hepatotoxicity through derangement of bile acid disposition; results also suggest that pharmacogenomic markers may be useful to identify patients who may tolerate higher mithramycin doses. SIGNIFICANCE STATEMENT: The present study characterizes a novel mechanism of drug-induced hepatotoxicity in which mithramycin not only alters farnesoid X receptor (FXR) and small heterodimer partner gene expression but also inhibits bile acid binding to FXR, resulting in deregulation of cellular bile homeostasis. Two novel single-nucleotide polymorphisms in bile flow transporters are associated with mithramycin-induced liver function test elevations, and the present results are the rationale for a genotype-directed clinical trial using mithramycin in patients with thoracic malignancies.

MicroRNA-215-5p Treatment Suppresses Mesothelioma Progression via the MDM2-p53-Signaling Axis

Malignant pleural mesothelioma (MPM) is an incurable, aggressive neoplasm with distinctive features, including preservation of wild-type p53, irrespective of histologic subtype. We posited that this consistent molecular characteristic represents an underexploited therapeutic target that can be approached by leveraging biologic effects of microRNA (miRNA). The Cancer Genome Atlas was surveyed to identify p53-responsive prognostic miRNA(s) in MPM. Using patient samples, in vitro MPM cell lines, and murine tumor xenograft models, we verified specific gene pathways targeted by these miRNAs, and we examined their therapeutic effects. miR-215-5p is a poor prognosis miRNA downregulated in MPM tissues, which has not been recognized previously. When miR-215-5p was ectopically re-expressed in MPM cells and delivered in vivo to tumor xenografts, it exerted significant cell killing by activating p53 function and inducing apoptosis. The mechanistic basis for this effect is due to combinatorial effects of a positive feedback loop of miR-215-MDM2-p53 signaling, additional mouse double minute 2 (MDM2)-p53 positive feedback loop(s) with other miRNAs such as miR-145-5p, and suppression of diverse gene targets associated with cell cycle dynamics not previously drug treatable in MPM clinical studies. Our results suggest a potential pathophysiologic role for and therapeutic significance of miR-215-5p in MPM.

Metadherin Is a Prognostic Apoptosis Modulator in Mesothelioma Induced via NF-κB-Mediated Signaling

Therapies against malignant pleural mesothelioma (MPM) have yielded disappointing results, in part, because pathologic mechanisms remain obscure. In searching for rational molecular targets, we identified metadherin (MTDH), a multifunctional gene associated with several tumor types but previously unrecognized in MPM. Cox proportional hazards regression analysis delineated associations between higher MTDH expression and lower patient survival from three independent MPM cohorts (n = 349 patients). Through in vitro assays with overexpression and downregulation constructs in MPM cells, we characterized the role of MTDH. We confirmed in vivo the phenotype of altered MTDH expression in a murine xenograft model. Transcriptional regulators of MTDH were identified by chromatin immunoprecipitation. Overexpression of both MTDH mRNA (12-fold increased) and protein levels was observed in tumor tissues. MTDH stable overexpression significantly augmented proliferation, invasiveness, colony formation, chemoresistance, and an antiapoptosis phenotype, while its suppression showed opposite effects in MPM cells. Interestingly, NF-κB and c-Myc (in a feed-forward loop motif) contributed to modulating MTDH expression. Knockdown of MTDH expression profoundly retarded xenograft tumor growth. Thus, our findings support the notion that MTDH integrates upstream signals from certain transcription factors and mediates pathogenic interactions contributing to MPM traits. MTDH represents a new MPM-associated gene that can contribute to insights of MPM biology and, as such, suggest other treatment strategies.

Immunologic Recognition of a Shared p53 Mutated Neoantigen in a Patient with Metastatic Colorectal Cancer

Adoptive cell therapy (ACT) with T cells targeting neoantigens can mediate durable responses in patients with metastatic cancer. Cell therapies targeting common shared antigens for epithelial cancers are not yet broadly available. Here, we report the identification and characterization in one patient of T-cell receptors (TCRs) recognizing mutated p53 p.R175H, which is shared among a subset of patients with cancer. Tumor-infiltrating lymphocytes were screened for recognition of mutated neoantigens in a patient with metastatic colorectal cancer. HLA-A*0201-restricted recognition of mutated p53 p.R175H was identified, and the minimal peptide epitope was HMTEVVRHC. Reactive T cells were isolated by tetramer sorting, and three TCRs were identified. These TCRs mediated recognition of commercially available ovarian cancer, uterine carcinoma, and myeloma cell lines, as well as an NIH patient-derived esophageal adenocarcinoma line that endogenously expressed p53 p.R175H and HLA-A*0201. They also mediated recognition of p53 p.R175H⁺ colon, breast, and leukemia cell lines after transduction with a retrovirus encoding HLA-A*0201. This work demonstrates that common shared mutated epitopes such as those found in p53 can elicit immunogenic responses and that the application of ACT may be extended to patients with any cancer histology that expresses both HLA-A*0201 and the p53 p.R175H mutation.

CD38 knockout suppresses tumorigenesis in mice and clonogenic growth of human lung cancer cells

The ectodomain of the plasma membrane ectoenzyme CD38 functions as both an NAD glycohydrolase and an ADP-ribosyl cyclase by catalyzing, respectively, the conversion of NAD to nicotinamide and ADP-ribose or cyclic ADP-ribose. CD38 is attracting particular attention in cancer therapy. An anti-CD38 monoclonal antibody (daratumumab) was approved for treatment of patients with multiple myeloma. However, the role of CD38 in non-hematological malignancies has not been explored. Previously, we reported that ADP-ribose-acceptor hydrolase (ARH)-1 deficiency in mice was associated with tumor development. In the present study, we found that in wild-type and ARH1-deficient mice deletion of the CD38 gene reduced tumor formation. Significant reductions in tumor number were observed in lymphomas, adenocarcinomas and hemangio/histolytic sarcomas. Consistent with a role for CD38 in tumorigenesis, CRISPR/Cas9-based knockout of CD38 in A549 human adenocarcinoma cells inhibited anchorage-independent cell growth, cell invasion and xenograft growth in nude mice. CD38 mRNA and protein expression were evaluated in human lung cancer cell lines and in human lung cancer specimens. CD38 overexpression in tumor cells was identified in 11 of 27 patient samples. In addition, some human lung cancer cell lines had dramatically higher CD38 mRNA and protein expression than normal cells. Consistent with these observations, search of the Oncomine database showed that some human lung adenocarcinomas had higher CD38 mRNA levels compared to normal lung tissues. In total, our data are consistent with the conclusion that CD38 plays a role in murine and human lung tumorigenesis and that anti-CD38 treatment may have therapeutic potential in lung cancer.

Abstract 523: miR-206 inhibits pleural mesothelioma by targeting an active KRAS/CDK4/CCND1 pathway

Introduction: Since there remains no effective, durable chemotherapy against malignant pleural mesothelioma (MPM), we propose to leverage microRNA(miR)-based approaches that recently reached phase I trial testing. We posit there are many miR with therapeutic potential yet to be identified in MPM. Methods/ Results: Our prior miRNA expression profiling results of MPM (GSE40345) were cross-referenced with a novel p-value minimization analytic technique to identify prognostic miRNA. Both MPM cell lines and tissues (tumors and normal pleura) were assessed using quantitative and functional biologic assays. In silico algorithms identified gene targets that were verified by 3'-UTR luciferase assay.In silico analyses showed underexpression of miR-206 by 12.1-fold in MPM tumors compared to normal pleura. Using our p-value minimization technique, we assessed the clinical impact of this underexpressed miR in TCGA data (n=73 MPM) and noted a significant association to worse survival for patients with lower miR-206 expression (p=0.024). We confirmed that miR-206 was significantly underexpressed in tumor tissues by qRT-PCR analysis of a new, randomly selected MPM cohort (n=41) versus normal pleura (n=14). In a set of established MPM cell lines with low endogenous miR-206 level, ectopic re-expression of miR-206 dramatically suppressed cell proliferation, invasiveness, colony foci formation, and growth in soft-agar. Treatment of non-malignant mesothelial cells MeT-5a and LP9 with ectopic miR-206 showed no untoward effects. In silico gene target predictions for miR-206 were summated across 3 databases and screened by prognostic effect based on Kaplan-Meier results from TCGA data (n=87 MPM). Interestingly, we noted several overexpressed MPM-prognostic genes (p&lt;0.05) regulated by miR-206: KRAS, CDK4, and CCND1. qRT-PCR analysis of tissues confirmed elevated transcripts of KRAS, CDK4, and CCND1 in MPM. This signaling axis of KRAS/CDK4/CCND1 is important in MPM as it summates well-known dysregulated tyrosine kinase receptors (EGF, IGF-1, VEGF, MET, etc) that are upstream. The KRAS/CDK4/CCND1 axis is associated with cell cycle progression and survival of cancer cells, but is not an easily druggable target. miR-206 treatment significantly downregulated KRAS, CDK4 and CCND1 genes in MPM cell lines. Conclusion: In vitro, miR-206 exerts tumor suppressive effects in MPM via inhibition of KRAS/CDK4/CCND1 signaling. miR-206 restoration in MPM mimics simultaneous blocking of multiple tyrosine kinases. Loss of miR-206 and concomitant overexpression of KRAS, CDK4 and CCND1 formed a poor prognostic signature of MPM. Our results identify miR-206 as a rational therapeutic agent to studied further in preclinical MPM models.

Citation Format: Anand Singh, Roma Pahwa, Li Zhang, Nathanael Pruett, R Taylor Ripley, David S. Schrump, Chuong D. Hoang. miR-206 inhibits pleural mesothelioma by targeting an active KRAS/CDK4/CCND1 pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 523.

Induction of Thioredoxin-Interacting Protein by a Histone Deacetylase Inhibitor, Entinostat, Is Associated with DNA Damage and Apoptosis in Esophageal Adenocarcinoma

In 2017, an estimated 17,000 individuals were diagnosed with esophageal adenocarcinoma (EAC), and less than 20% will survive 5 years. Positron emission tomography avidity is indicative of high glucose utilization and is nearly universal in EAC. TXNIP blocks glucose uptake and exhibits proapoptotic functions. Higher expression in EAC has been associated with improved disease-specific survival, lack of lymph node involvement, reduced perineural invasion, and increased tumor differentiation. We hypothesized that TXNIP may act as a tumor suppressor that sensitizes EAC cells to standard chemotherapeutics. EAC cell lines and a Barrett epithelial cell line were used. qRT-PCR, immunoblot, and immunofluorescence techniques evaluated gene expression. TXNIP was stably overexpressed or knocked down using lentiviral RNA transduction techniques. Murine xenograft methods examined growth following overexpression of TXNIP. Apoptosis and DNA damage were measured by annexin V and γH2AX assays. Activation of the intrinsic apoptosis was quantitated with green fluorescence protein-caspase 3 reporter assay. In cultured cells and an esophageal tissue array, TXNIP expression was higher in Barrett epithelia and normal tissue compared with EAC. Constitutive overexpression of TXNIP decreased proliferation, clonogenicity, and tumor xenograft growth. TXNIP overexpression increased, whereas knockdown abrogated, DNA damage and apoptosis following cisplatin treatment. An HDAC inhibitor, entinostat (currently in clinical trials), upregulated TXNIP and synergistically increased cisplatin-mediated DNA damage and apoptosis. TXNIP is a tumor suppressor that is downregulated in EACC. Its reexpression dramatically sensitizes these cells to cisplatin. Our findings support phase I/II evaluation of "priming" strategies to enhance the efficacy of conventional chemotherapeutics in EAC. Mol Cancer Ther; 17(9); 2013-23. ©2018 AACR.

Metabolomic and BH3 profiling of esophageal cancers: novel assessment methods for precision therapy

BACKGROUND

Esophageal cancers accounted for nearly 16,000 deaths in 2016. The number of patients with esophageal cancers increases every year. Neoadjuvant chemoradiotherapy (nCRT) prior to esophagectomy is a standard treatment for esophageal cancers. The patients who have no residual tumor (pathological complete response (pCR)) at surgery are the most likely to experience long term survival. Accurately determining which patients will have a pCR will improve prognostic information for patients and families, confirm lack of response to nCRT, or avoid surgery if no residual tumor is present. Imaging, endoscopy, and liquid biomarkers have all failed to detect pCR without performing an esophagectomy.

METHODS

In this study, we are enrolling patients with esophageal adenocarcinoma and squamous cell carcinoma. Patients will undergo standard evaluation including CT scans, laboratory tests, endoscopy with biopsies, and evaluation by a thoracic surgeon. Tissue biopsy is required for enrollment that will be sent for BH3 profiling and metabolomics. Patients will be treated with standard nCRT followed by surgery. Patients with metastatic disease are not eligible. Surgery at the National Cancer Institute will be minimally-invasive robotic surgery. Patients will remain on study indefinitely with regular clinic visits and imaging tests.

DISCUSSION

The mitochondria are critically involved in the intrinsic pathway apoptosis. Bcl-2 homology domain 3 (BH3) profiling is a technique to measure a cell's susceptibility to apoptosis. BH3 profiling measures the relative interactions of proteins that induce or block apoptosis. The collective balance of these proteins determines whether a cell is near the threshold to undergo apoptosis. If the cell is near this threshold, then the tumor may be more likely to die when treated with nCRT. The mitochondria secrete metabolites that may be detectable as biomarkers. Metabolomics is a global assessment of all metabolite changes that has been performed for detection, monitoring, prognosis, and treatment response in cancers. Stratification of patients based on whether pCR occurs or not may elucidate metabolomic signatures that may be associated with response. We are asking whether BH3 profiling or a metabolomic signature will correlate with tumor death after nCRT for esophageal cancer.

TRIAL REGISTRATION

NCT03223662 ; Clinicaltrials.gov. July 21, 2017.

Comprehensive immunohistochemical study of mesothelin (MSLN) using different monoclonal antibodies 5B2 and MN-1 in 1562 tumors with evaluation of its prognostic value in malignant pleural mesothelioma

Mesothelin (MSLN) is a glycophosphatidylinositol (GPI)-linked cell surface protein highly expressed in several types of malignant tumors sometimes in association with increased tumor aggressiveness and poor clinical outcome. In the present study, 1562 tumors were immunohistochemically analyzed for mesothelin expression using two different types of mouse monoclonal antibodies (5B2 and MN-1) to determine the clinical usefulness of mesothelin immunohistochemistry as well as to pinpoint potential targets for future anti-mesothelin therapy. Also, characterization of selected mesothelin-positive tumors was performed by immunohistochemistry and oncogene sequencing. Among the tumors analyzed, the highest frequencies of mesothelin-positivity were detected in ovarian serous carcinoma (90% in 5B2 and 94% in MN-1). Both antibodies showed frequent positivity in pancreatic adenocarcinoma (71% using 5B2 and 87% using MN-1) and malignant pleural mesothelioma (75% using 5B2 and 78% using MN-1). In malignant mesothelioma, overall survival was significantly longer in the cohort of patients with diffuse membranous expression of mesothelin (P < 0.001). Both antibodies showed positive staining in thymic carcinoma (77% in 5B2 and 59% in MN-1), however, no expression was detected in thymoma. No correlation was detected between mesothelin expression and mismatch repair system deficient phenotype or gene mutation (BRAF and RAS) status in gastrointestinal adenocarcinomas. Mesothelin immunohistochemistry may assist the differential diagnosis of thymoma vs. thymic carcinoma as well as prognostication of mesothelioma patients. Our results demonstrate that patients with solid tumors expressing mesothelin could be targeted by anti-mesothelin therapies.

Bile acid and cigarette smoke enhance the aggressive phenotype of esophageal adenocarcinoma cells by downregulation of the mitochondrial uncoupling protein-2

Limited information is available regarding mechanisms that link the known carcinogenic risk factors of gastro-esophageal reflux and cigarette smoking to metabolic alterations in esophageal adenocarcinoma (EAC). In the present study, we utilized a novel in-vitro model to examine whether bile acid and cigarette smoke increase the aggressiveness of EAC and whether these changes are associated with metabolic changes. EAC cells (EACC) were exposed to 10 μg/ml cigarette smoke condensate (CSC) and/or 100 μM of the oncogenic bile acid, deoxycholic acid (DCA), for 5 days. These exposure conditions were chosen given their lack of effect on proliferation or viability. DCA and CSC increased invasion, migration, and clonogenicity in EAC cells. These changes were associated with concomitant increases in ATP, ROS, and lactate production indicative of increased mitochondrial respiration as well as glycolytic activity. DCA and CSC exposure significantly decreased expression of uncoupling protein-2 (UCP2), a mitochondrial inner membrane protein implicated in regulation of the proton gradient. Knockdown of UCP2 in EACC phenocopied DCA and CSC exposure as evidenced by increased cell migration, invasion, and clonogenicity, whereas over-expression of UCP2 had an inverse effect. Furthermore, over-expression of UCP2 abrogated DCA and CSC-mediated increases in lactate and ATP production in EACC. DCA and CSC promote the aggressive phenotype of EACC with concomitant metabolic changes occurring via downregulation of UCP2. These results indicate that UCP2 is integral to the aggressive phenotype of EACC. This mechanism suggests that targeting alterations in cellular energetics may be a novel strategy for EAC therapy.

Genomic profiling of multiple sequentially acquired tumor metastatic sites from an "exceptional responder" lung adenocarcinoma patient reveals extensive genomic heterogeneity and novel somatic variants driving treatment response

We used next-generation sequencing to identify somatic alterations in multiple metastatic sites from an “exceptional responder” lung adenocarcinoma patient during his 7-yr course of ERBB2-directed therapies. The degree of heterogeneity was unprecedented, with ∼1% similarity between somatic alterations of the lung and lymph nodes. One novel translocation, PLAG1-ACTA2, present in both sites, up-regulated ACTA2 expression. ERBB2, the predominant driver oncogene, was amplified in both sites, more pronounced in the lung, and harbored an L869R mutation in the lymph node. Functional studies showed increased proliferation, migration, metastasis, and resistance to ERBB2-directed therapy because of L869R mutation and increased migration because of ACTA2 overexpression. Within the lung, a nonfunctional CDK12, due to a novel G879V mutation, correlated with down-regulation of DNA damage response genes, causing genomic instability, and sensitivity to chemotherapy. We propose a model whereby a subclone metastasized early from the primary site and evolved independently in lymph nodes.