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M.S. Tsao



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    MO05 - Prognostic and Predictive Biomarkers II (ID 95)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Medical Oncology
    • Presentations: 1
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      MO05.11 - The Effect of Two BRM Promoter Polymorphisms on the Risk of Advanced Non-Small Cell Lung Cancer (NSCLC) and Small Cell Lung Cancer (SCLC) in Smokers (ID 1987)

      17:15 - 17:20  |  Author(s): M.S. Tsao

      • Abstract
      • Presentation
      • Slides

      Background
      BRM, an ATPase subunit of the SWI/SNF chromatin remodeling complex, is a putative tumor susceptibility gene in lung cancer. Loss of BRM expression occurs in 15% of lung cancers. Two BRM promoter insertion polymorphisms (BRM-741 and BRM-1321) lead to epigenetic silencing of BRM and highly correlate with loss of BRM expression and function in lung tumors. Pharmacologic reversal of the epigenetic changes of BRM is feasible. We previously demonstrated a strong risk association between these two polymorphisms and susceptibility to early stage NSCLC. Here, we evaluate the association between the two BRM polymorphisms and risk of developing: 1) advanced NSCLC, and 2) SCLC among smokers.

      Methods
      Genotyping for BRM promoter polymorphisms was performed using TaqMan. The cohorts analyzed were: 1) 417 stage III-IV NSCLC cases and 2) 111 SCLC cases treated at the Princess Margaret Cancer Centre (PMCC), Toronto; and 3) 43 SCLC cases from the University of Florida (U of F), all with a smoking history of ≥1 pack-year. Cases were matched to healthy controls by frequency distribution (1:2 for PMCC cases; 1:1 for U of F cases) based on age, gender, pack-year smoking history, and either current smoking status (PMCC) or ethnicity (U of F). Adjusted odds ratios (aORs) with their 95% confidence intervals (CI) of the association between polymorphisms and lung cancer risk were estimated by multiple logistic regression models.

      Results
      Of the 417 NSCLC cases, 59% were male; 41%, current smokers; 63%, adenocarcinoma; 51%, stage IV; median age, 63 years. The frequency of homozygosity was BRM-741, 21%; BRM-1321, 20%; both, 11%. The homozygous variants of BRM-741 and BRM-1321 were associated with an increased risk of advanced NSCLC compared to the wild types, with aOR’s of 1.6 (95% CI: 1.1-2.2; p=0.008) and 1.4 (95% CI: 1.0-2.0; p=0.04), respectively. Being homozygous for both BRM promoter variants carried an even greater risk (aOR 2.4 [95% CI: 1.4-4.0; p=0.0009]), with the strongest effect observed among current smokers (aOR 3.4; p=0.0005), and those with a histological diagnosis other than adenocarcinoma (aOR 3.2; p=0.0005). Among the 111 PMCC SCLC cases, 62% were male; 56%, current smokers; median age 65 years; of the 43 U of F SCLC cases, 35% were male; median age, 63 years. The presence of double homozygous variants of BRM-741 and BRM-1321 had no effect on the risk of developing SCLC in either of the two cohorts analyzed, with aOR’s of 1.1 (95% CI: 0.3-3.5; p=0.94) and 0.3 [95% CI: 0.04-2.41; p=0.27), respectively.

      Conclusion
      The presence of double homozygous variants of the BRM promoter polymorphisms, BRM-741 and BRM-1321, significantly increases the risk of advanced NSCLC among individuals with a smoking history greater than one year, with the strongest effect observed among current smokers. In contrast, the same two polymorphisms had no effect on the risk of developing SCLC in either of the two cohorts analyzed. Thus, this study offers further insight into potential mechanisms underlying the genetic susceptibility to developing advanced NSCLC among smokers. Validation in larger populations is warranted.

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    O01 - Prognostic and Predictive Biomarkers I (ID 94)

    • Event: WCLC 2013
    • Type: Oral Abstract Session
    • Track: Medical Oncology
    • Presentations: 1
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      O01.03 - BRM Promoter Variants and Survival Outcomes of Advanced Non-Small Cell Lung Cancer (NSCLC) Patients: A Validation Study in the NCIC Clinical Trials Group (NCIC-CTG) BR24 Clinical Trial (ID 1999)

      10:50 - 11:00  |  Author(s): M.S. Tsao

      • Abstract
      • Presentation
      • Slides

      Background
      BRM, an ATPase subunit of the SWI/SNF chromatin remodeling complex, is a putative tumor susceptibility gene in NSCLC. Loss of BRM expression occurs in 15% of NSCLC, and has been linked to adverse outcome. Two BRM promoter insertion variants (BRM-741 and BRM-1321) result in epigenetic silencing of BRM through recruitment of histone deacetylases. The presence of double homozygous BRM variants is linked to loss of BRM expression and function in lung tumors, and double the risk of lung cancer. Pharmacological reversal of the epigenetic changes of BRM is feasible. In this study we evaluated the association between the BRM promoter variants and survival outcomes of advanced NSCLC patients.

      Methods
      The training cohort consisted of 564 stage III-IV NSCLC patients treated at the Princess Margaret Cancer Centre, Toronto 2006-2010. The validation cohort comprised 219 stage IIIb-IV NSCLC patients from the NCIC-CTG BR24 clinical trial, a phase II/III double-blind randomized trial of cediranib versus placebo in patients receiving carboplatin/paclitaxel for the treatment of advanced or metastatic NSCLC. Genotyping for the BRM promoter variants was performed using Taqman. Associations of BRM promoter variants and overall (OS) and progression free survival (PFS) were assessed using Cox proportional hazard models adjusted for clinically relevant variables, and in the case of the BR24 population, stratified by treatment arm.

      Results
      Among the training cohort, 73% were Caucasian, 52% male, median age 63 yrs, 55% stage IV disease, and 67% adenocarcinoma. Median OS was 1.6yrs; median follow up, 3.6yrs. The frequency of homozygosity was BRM-741, 23%; BRM-1321, 21%; both 12%. Homozygous variants of BRM-741 were strongly associated with worse OS (adjusted HR [aHR] 2.5 [95% CI: 1.9-3.3; p=6x10E-10]) and PFS (aHR 2.0 [95% CI: 1.6-2.6; p=9x10E-8]) compared to the wild types. Similar findings were observed for the BRM-1321 homozygous variants (aHR for OS of 2.0 [95% CI: 1.5-2.6; p=2x10E-6]; aHR for PFS of 1.8 [95% CI: 1.4-2.4; p=3x10E-6]). The presence of double homozygous BRM-741 and BRM-1321 variants was strongly associated with worse OS (aHR 2.8 [95% CI: 1.9-4.0; p=7x10E-8]) and PFS (aHR 2.7 [95% CI: 1.9-3.8; p=1x10E-8]). Genotyping was possible for 219/296 BR24 participants. Of these, 59% were male, median age 59 yrs, 83% stage IV, 46% adenocarcinoma, with 50% receiving cediranib. Individuals carrying the homozygous variants of both BRM-741 and BRM-1321 (13% of cases) had a substantially worse OS (aHR 9.0 [95% CI: 4.3-18.5; p=1x10E-9]) and PFS (aHR 3.8 [95% CI: 1.9-7.3; p=3x10E-5]) compared to the wild types, irrespective of whether they were treated with cediranib (aHR for OS of 6.4; p=1x10E-4; aHR for PFS of 2.1; p=0.02) or placebo (aHR for OS of 16.8; p=2x10E-7; aHR for PFS of 8.3; p=1x10E-4).

      Conclusion
      The same two homozygous BRM promoter variants that are associated with increased risk of NSCLC are also strongly associated with adverse OS and PFS in this study of advanced NSCLC patients. We are completing additional studies focusing on the relationship between the BRM promoter variants and BRM protein expression; results will be presented at the meeting.

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    P2.06 - Poster Session 2 - Prognostic and Predictive Biomarkers (ID 165)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
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      P2.06-023 - Gene expression signature and immunohistochemical assessment of NRF2 pathway activation for adjuvant chemotherapy benefit in lung squamous cell carcinoma (SqCC) (ID 1990)

      09:30 - 09:30  |  Author(s): M.S. Tsao

      • Abstract

      Background
      Genomic profiling of SqCC has identified somatic alterations in NRF2 or its negative regulators (NFE2L2 mutations/amplifications, KEAP1 or CUL3 mutations/deletions) in ~1/3 of tumors. These alterations result in activation of the NRF2 transcriptional program, but the clinical significance of this pathway in lung SqCC patients is unknown. We hypothesize that a gene expression signature that reflects somatic NRF2-activating alterations may be identified and correlated with NRF2 protein over-expression. Furthermore, such gene expression or its immunohistochemical correlates may have prognostic significance and/or may be predictive of adjuvant chemotherapy benefit in early stage resectable lung SqCC patients.

      Methods
      Logistic regression (LR) and SAM analysis were applied independently to 104 SqCC cases from The Cancer Genome Atlas (TCGA) that had both microarray gene expression and mutation data to identify genes associated with NRF2 pathway mutational status. Overlapping genes were used to define the signature, which was then tested in 3 independent SqCC microarray datasets to evaluate its prognostic value. Correlation of the signature with NRF2 and KEAP1 mutations and with NRF2 and KEAP1 immunoreactive protein expression by immunohistochemistry (IHC) was evaluated. We also tested the gene expression signature as a potential predictor of adjuvant chemotherapy benefit in a subset of NCIC JBR.10 adjuvant chemotherapy trial patients with microarray data.

      Results
      A 28-gene signature that distinguished SqCC with or without aberration of the NRF2 pathway genes (NFE2L2/KEAP1/CUL3) in the TCGA dataset was identified. This gene signature that putatively represents NRF2 pathway activation status separates consistently SqCC into 2 groups in independent datasets. Both NRF2/KEAP1 mutation and NRF2 protein expression by IHC were significantly correlated with the NRF2 pathway activation signature (p<0.001 for each comparison). KEAP1 protein expression was not associated with the gene expression signature. No prognostic effect of the activated signature was observed in three independent datasets. In the JBR.10 patient cohort, a trend toward improved survival with adjuvant chemotherapy was observed in patients with the NRF2 “wild type” signature (HR 0.32, 95%CI 0.065-1.6 p=0.16), but not in patients with the “activated” signature (HR 2.28, 95%CI 0.24–22, p=0.48; interaction p=0.15).

      Conclusion
      A gene expression signature based on mutational activation of the NRF2 pathway may be predictive of benefit from adjuvant cisplatin/vinorelbine in SqCC. Patients with NRF2 pathway activating somatic alterations may have reduced benefit from this therapy. NRF2 immunohistochemistry could potentially be useful to identify NRF2-activated lung SqCC patients who may not benefit from adjuvant chemotherapy but this requires further validation.

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    P3.02 - Poster Session 3 - Novel Cancer Genes and Pathways (ID 149)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
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      P3.02-008 - TRIM14 is a Novel Tumor Suppressor Gene in Non-Small-Cell Lung Cancer (ID 1204)

      09:30 - 09:30  |  Author(s): M.S. Tsao

      • Abstract

      Background
      Non-small-cell lung carcinoma (NSCLC) accounts for 85% of all malignant lung tumors. Our group previously identified Tripartite Motif-Containing 14 (TRIM14) as a component of a prognostic multigene expression signature for NSCLC patients. TRIM14 belongs to a conserved family of Tripartite Motif-encoding genes involved in a broad range of biological processes, such as transcriptional regulation, cell proliferation, and apoptosis. However, TRIM14 itself is poorly understood. Here we investigate the functional and prognostic role of TRIM14 in NSCLC.

      Methods
      Cox proportional hazards regression analysis was done on published mRNA expression datasets of primary NSCLCs to identify whether TRIM14 expression is associated with patient survival. The expression of TRIM14 was modified in human NSCLC cell lines (NCI-H1395, NCI-H1650, NCI-H520 and NCI-H157) by lentivirus-mediated overexpression and short-hairpin RNA (shRNA)-mediated silencing. Effects were assessed by examining in vitro cell proliferation and anchorage-independent growth, and in vivo tumorigenicity in mice.

      Results
      Univariate analyses demonstrated that TRIM14 expression is significantly associated with patient survival, with loss of expression correlated with poorer prognosis in resectable early stage NSCLC patients. In vitro studies showed that TRIM14 overexpression in H1395 cells suppressed proliferation and anchorage-independent growth, whereas shRNA knockdown of TRIM14 expression in H1650, H520, and H157 cells promoted cell proliferation and colony formation. In vivo studies demonstrated that suppressing TRIM14 expression in H1650 and H157 cells significantly promotes tumor growth in immunodeficient mice.

      Conclusion
      We show that TRIM14 may function as a tumor suppressor gene in NSCLC affecting cell proliferation and anchorage-independent growth in vitro and tumor growth in mice. We provide evidence that prognostic genes identified in microarray based gene expression analyses may have a strong biological rationale.