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

Abstract

4539 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.