Abstract 1768: Investigating oncogene amplifications in brain metastasis of esophageal adenocarcinoma samples

Abstract Esophageal Adenocarcinoma (EAC) exhibits a rising incidence and dismal survival rate in the US, primarily attributed to frequent distant metastases. Brain metastasis, though uncommon is an aggressive tumor type, remains poorly understood in EAC. To address this knowledge gap, we conducted a comprehensive analysis of 9 brain metastasis samples, profiling their whole-genome with matched normal and comparing them to the primary EAC tumors, other EAC metastasis types and other brain metastasis types, including the Hartwig Institute and PCAWG. Overall, our sample size comprised over 4,500 tumor whole-genome data and we utilized a uniform data analysis pipeline for robust comparisons between cohorts. Our analysis revealed that brain metastasis samples have significantly higher single-nucleotide variants, however, the structural variant burden in brain metastases closely resembled those observed in the primary tumor. Notably, the incidence of whole genome doubling is significantly higher in brain metastasis compared to other primary cancer types and metastases. This significant difference stems from the higher WGD incidence in primary EACs compared to other tumor types. Mutational signature analysis revealed no significant changes compared to the primary tumor, and we observed an enrichment of SBS 17a/b, previously associated with tumor progression in primary esophageal adenocarcinoma, along with a prevalent presence of the APOBEC mutagenesis signature in most samples. Notably, ERBB2 and TP53 emerged as prominent driver genes present in most brain metastasis samples. We also observed an upregulation of ERBB2 expression in brain metastasis samples. Interestingly, ERBB2 appeared to play a more significant role in brain metastasis progression compared to the primary tumor and other metastasis types, suggesting its potential as a therapeutic target. These findings advance our comprehension of brain metastasis in EAC, providing crucial insights into genomic alterations and mutational processes that could inform future therapeutic strategies and clinical management for this previously understudied metastatic type. Citation Format: Nora Lawson, Lingqun Ye, Bo Zhao, Andy Futreal, Kadir Akdemir. Investigating oncogene amplifications in brain metastasis of esophageal adenocarcinoma samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1768.