Translational analysis of esophageal adenocarcinoma (EAC) patients treated with oxaliplatin and capecitabine (Xelox) +/- the dual ErbB inhibitor AZD8931 in the DEBIOC study

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Background: The Dual Erb B Inhibition in Oesophago-gastric Cancer (DEBIOC) trial reported an acceptable safety profile for neoadjuvant Xelox +/- AZD8931 but limited efficacy. We utilized EAC patient samples from DEBIOC to evaluate the impact of neoadjuvant Xelox +/-AZD8931 on biological pathways using a unique software driven solution. Methods: 24 pre-treatment FFPE EAC biopsies and 17 matched surgical resection specimens were transcriptionally profiled using the Almac Diagnostics Xcel Array. Gene expression data was analyzed using the Almac claraT total mRNA report V3.0.0, reporting on 92 gene expression signatures and 7337 single genes associated with 10 key biologies. Paired Wilcoxon tests (5% significance level) were used to evaluate changes in claraT scores pre- and post-treatment. EGFR and Her2 expression were assessed by IHC and FISH. Results: 15 patients received Xelox+AZD8931 and 9 Xelox alone. Hierarchical clustering of biopsies identified 4 major clusters: Inflammation active, Genomic Instability active, EGFR & MAPK active, and EMT & Angiogenesis active. Comparison of signature scores pre- and post- neoadjuvant treatment demonstrated a significant reduction in scores relating to DNA damage repair (DDR) deficiency (Almac DNA Damage assay, p< 0.0001; BRCAness Profile, p= 0.0025; HRD Gene Signature, p< 0.0001; BRCA1ness Signature, p= 0.0004) and a significant increase in angiogenesis signatures (Almac Angiogenesis Assay, p= 0.0002; Angio Predictive G model, p= 0.0228; Angiogenesis Signature A, p= 0.0034) and EMT signatures (EMT Signature, p= 0.0031, EMT Enrichment Score, p= 0.0013, Pan-Can EMT Signature B, p= 0.0001). Comparing pre- and post-treatment signature scores in patients treated with Xelox +/-AZD8931 revealed a significant reduction in EGFR Sensitivity Signature ( p= 0.0088), ERBB2-specific Gene Expression Signature ( p= 0.0127) and Hallmark PI3K-AKT-MTOR Signaling ( p= 0.0195) in those treated with Xelox + AZD8931 in keeping with the mechanism of action of AZD8931. Downregulation of AKT signaling was confirmed in AZD8931 treated and resistant cell lines. Conclusions: We report the use of a novel software tool to apply 92 gene expression signatures to EAC biopsy and resection specimens from the DEBIOC trial to provide insight into mechanisms of action. Neoadjuvant treatment was associated with a reduction in DDR deficiency and an increase in angiogenesis and EMT signatures whilst a reduction in EGFR, Her2 and AKT pathways was noted with AZD8931 treatment.

Consensus gene expression analysis to identify key hallmarks of cancer in malignant melanoma

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Background: Traditionally gene expression signatures (GES) are used individually to classify patients into subgroups. Signatures targeting the same biology are often developed independently and may not classify identically. We developed the claraT software tool that uses consensus between multiple published GES categorised by the Hallmarks of Cancer (Hanahan & Weinberg, 2011) to classify cancers. As metastatic melanoma represents poor prognostic disease (5-yr survival 15-20%), we applied claraT to the TCGA melanoma dataset to identify targetable biologies, validated in a cohort of melanoma patients treated with Ipilimumab. Methods: TCGA RNA-seq data ( n= 472) was analysed using the claraT platform including GES for immune ( n= 14), angiogenesis ( n= 9) and epithelial-mesenchymal transition (EMT) ( n= 12) Hallmarks. Samples were clustered for the combined and individual Hallmarks. Median progression-free (PFS) and overall-survival (OS) differences were analysed across identified subgroups. Analysis was validated in an Ipilimumab treated melanoma dataset ( n= 42) (Van Allen, 2015). Results: Clustering the combined Hallmarks identified 4 subgroups in the TCGA cohort: 1) Immune active, 2) Immune-EMT active, 3) EMT-Angiogenesis active, 4) All inactive. Groups 1&2 had significantly improved OS compared to Groups 3&4 (HR = 0.50, p< 0.0001). Clustering using single Hallmarks revealed that immune-positive tumours had significantly improved OS (HR = 0.53, p< 0.0001) compared to immune-negative tumours. Angiogenesis-negative tumours displayed improved PFS (HR = 0.73, p= 0.03) and OS (HR = 0.53, p <0.0001) compared to angiogenesis-negative tumours. Interestingly the EMT Hallmark was not found to be individually prognostic. When validated in the Ipilimumab treated dataset, patients classified as immune-positive had improved OS (HR = 0.357, p= 0.010) when compared to immune-negative. Similar trends were also observed for angiogenesis and EMT Hallmarks. Conclusions: This study demonstrates how simultaneous analysis of multiple GES ( n= 35 in this study) can identify robust biologies through consensus expression. This platform may have value in the identification of reliable biomarkers for clinical trials and could inform how combination therapies targeting key biologies may be used in cancer treatment.

Abstract 578: Loss of MED12 predicts for a DNA damage repair deficiency phenotype and activates immune signalling via the STING pathway

Introduction: Genome integrity is maintained by a number of pathways which recognize and repair both exogenous and endogenous DNA damage. Deficiency in these pathways results in mutations that accelerate tumorigenesis. A subgroup of cancers such as those with mutations in the BRCA/ Fanconi anemia (FA) pathway have been reported to benefit from DNA damaging chemotherapy. Previously, we identified a molecular subgroup in breast cancer characterised by upregulation of immune genes. This group referred to as the DNA damage repair deficient (DDRD) group also showed enhanced response to DNA damaging chemotherapy. Here, we identify the same subgroup in prostate cancer and investigate the mutations associated with the subgroup in prostate cancer. Experimental procedures: Unsupervised hierarchical clustering in primary prostate cancer identified a subset of patients which demonstrated activation of immune signalling genes and enrichment for BRCA mutations, representing the DDRD group. Using data from The Cancer Genome Atlas (TCGA), we show that mutation of the MED12 gene is associated with the DDRD group. In order to study the role of MED12 in prostate cancer, isogenic cell lines with knockdown of MED12 were generated using RNAi technology. We evaluated the expression of immune genes in these cell lines using RT-qPCR. Immunofluorescence, DNA-RNA immunoprecipitation and western blot analyses were also used in the characterization of these cell lines. Results: Our data reveals that the loss of MED12 leads to a significant upregulation of the immune genes associated with DNA repair deficiency; CXCL10, CCL5, MX1 and the immune check-pointing gene PD-L1 (p&lt;0.05). Accumulation of γH2AX foci was identified in cells depleted in MED12 (p&lt;0.001). A significant increase in DNA-RNA hybrids (Rloops) was also observed in MED12- deficient cells (p&lt;0.0001) indicating an endogenous source of genomic instability. Furthermore, we show the presence of cytosolic nucleic acid which triggers immune response via the STING/TBK1/IRF3 pathway which is characteristic of the DDRD-like phenotype in MED12-deficient cells.Conclusion: Mutations in the MED12 gene have previously been reported in 5 % of prostate cancer. Our findings demonstrate that the loss of MED12 in prostate cancer results in a DDRD-like phenotype. Upon further characterization, MED12 may be used as a predictor of response to stratify patients for chemotherapy or immune checkpoint targeted therapy in prostate cancer

Citation Format: Folake A. Orafidiya, Catherine Davidson, Richard D. Wilkinson, Steve M. Walker, Laura A. Knight, Paul D. Harkin, Nuala McCabe, Richard D. Kennedy. Loss of MED12 predicts for a DNA damage repair deficiency phenotype and activates immune signalling via the STING 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 578.

Association of a DNA damage response deficiency (DDRD) assay with prognosis in resected esophageal and gastric adenocarcinoma

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Background: Current strategies to guide the selection of neo-adjuvant or adjuvant therapy in esophageal and gastric adenocarcinomas (EAC/GAC) are inadequate. We assessed a clinically validated 44 gene DNA Damage Response Deficiency (DDRD) assay to predict prognosis following neo-adjuvant DNA damaging chemotherapy (CT) in EAC and adjuvant CT or chemo-radiotherapy (CRT) in GAC. Methods: Transcriptional profiling of 273 formalin fixed paraffin embedded pre-treatment endoscopic EAC biopsies was performed using the Almac Diagnostics Xcel array. All EAC patients were treated with cisplatin-based neo-adjuvant chemotherapy followed by surgical resection between 2003 and 2014 at four UK centers in the OCCAMS consortium. Further validation was performed using a publically available dataset of 270 resected gastric cancers treated with adjuvant platinum-based CT, CRT or surgery alone at the Samsung Medical Centre, Seoul, Korea. The association between the DDRD score and prognosis was assessed by Kaplan-Meier analysis and Cox Proportional Hazards regression. Results: A total of 66 EAC samples (24%) were characterized as DDRD positive with the remaining 207 samples (76%) being DDRD negative. DDRD assay positivity was associated with improved DFS (HR 0.58; 95% CI 0.36-0.93; p = 0.024) and OS (HR 0.56; 95% CI 0.34-0.92; p = 0.023) following multivariate analysis. DDRD positive patients had a higher pathological response rate (p = 0.033) and a higher rate of loco-regional versus distant relapse (30% vs 20%; p = 0.013). For GAC, 132 samples (49%) were characterized as DDRD positive with the remaining 138 (51%) being DDRD negative. DDRD positivity was associated with improved DFS (HR 0.48; 95% CI 0.25-0.96; p = 0.037) following D2 gastrectomy and adjuvant CT or CRT. DDRD status was not associated with DFS in the surgery alone cohort (HR 0.87; 95% CI 0.55-1.38; p = 0.562). Conclusions: The DDRD assay is strongly predictive of benefit from DNA damaging neo-adjuvant CT and esophagectomy in EAC and gastrectomy and CT/CRT in GAC and can be applied to routine diagnostic material.

A metastatic biology gene expression assay to predict the risk of distant metastases in patients with localized prostate cancer treated with primary radical treatment

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Background: Approximately 20% of patients with organ confined prostate cancer (PCa) will develop disease recurrence following radical treatment (surgery or external beam radiotherapy (EBRT)). We hypothesized that a molecular subgroup of early PCa may have metastatic potential at presentation, resulting in disease recurrence. Methods: Using unsupervised hierarchical clustering of gene expression from a PCa dataset we identified a novel molecular subgroup with a transcriptional profile similar to metastatic disease. We developed a 70 gene expression assay to prospectively identify patients within the subgroup from formalin fixed and paraffin embedded tissue (FFPE). Initial assessment found the assay to be prognostic in three independent publicly available prostatectomy datasets. We therefore assessed the prognostic value of the assay in FFPE clinical samples collected from multiple international sites. FFPE tumor resections and tumor biopsy specimens were obtained from 322 surgical patients and 248 patients treated with EBRT. Regions of highest Gleason grade were identified for macrodissection, RNA extraction and gene expression analysis. Samples were dichotomized as metastatic biology assay positive or negative using a pre-specified cut-off. The association of assay results with biochemical failure (BF) and distant metastases (DM) was tested on multivariate (MVA). Results: The assay was significantly associated with BF on MVA (HR 1.67 [1.16-2.38]; p = 0.0059), (HR 2.26 [1.26-4.04]; p = 0.0062) and DM on MVA (HR 3.39 [1.88-6.12]; p = 0.0001), (HR 3.26 [1.27-8.30]; p = 0.0137) for surgery and EBRT cohorts respectively. Importantly, in a combined model, the assay demonstrated additional information to the commonly used CAPRA clinical tool for prediction of DM, HR 2.72 [2.10-3.51]; p < 0.0001, and HR 2.72 [1.42-5.20]; p = 0.0026 (Prostate Metastatic Assay combined with CAPRA-S and CAPRA respectively). Conclusions: The metastatic biology assay predicts BF and DM in PCa patients treated with surgery or EBRT. The assay may help to select patients at risk of metastatic disease for additional treatment aimed at preventing disease recurrence.