Esophageal adenocarcinoma (EAC) has a poor outcome, and targeted therapy trials have thus far been disappointing due to a lack of robust stratification methods. Whole-genome sequencing (WGS) analysis of 129 cases demonstrates that this is a heterogeneous cancer dominated by copy number alterations with frequent large scale rearrangements. Co-amplification of receptor tyrosine kinases (RTKs) and/or downstream mitogenic activation is almost ubiquitous; thus tailored combination RTKi therapy might be required, as we demonstrate in vitro. However, mutational signatures reveal three distinct molecular subtypes with potential therapeutic relevance, which we verify in an independent cohort (n=87): i) enriched for BRCA signature with prevalent defects in the homologous recombination pathway; ii) dominant T>G mutational pattern associated with a high mutational load and neoantigen burden; iii) C>A/T mutational pattern with evidence of an ageing imprint. These subtypes could be ascertained using a clinically applicable sequencing strategy (low coverage) as a basis for therapy selection.

Esophageal adenocarcinoma (EAC) incidence is increasing while 5-year survival rates remain less than 15%. A lack of experimental models has hampered progress. We have generated clinically annotated EAC organoid cultures that recapitulate the morphology, genomic, and transcriptomic landscape of the primary tumor including point mutations, copy number alterations, and mutational signatures. Karyotyping of organoid cultures has confirmed polyclonality reflecting the clonal architecture of the primary tumor. Furthermore, subclones underwent clonal selection associated with driver gene status. Medium throughput drug sensitivity testing demonstrates the potential of targeting receptor tyrosine kinases and downstream mediators. EAC organoid cultures provide a pre-clinical tool for studies of clonal evolution and precision therapeutics.