432. SINGLE-CELL RNA SEQUENCING OF MORPHOLOGICALLY-PURE PATIENT-DERIVED ORGANOIDS FROM ESOPHAGEAL ADENOCARCINOMA PATIENTS

We have successfully cultured esophageal adenocarcinoma (EAC) patient-derived organoids (PDOs) from endoscopic biopsies. These PDOs recapitulate the histological and molecular features of the originating tumour and frequently exhibit morphological heterogeneity within the same patient sample. The underlying biology of these morphologies and their relation to treatment response remains unknown. This study will examine the gene expression profile of morphologically pure organoids. EAC tissue samples collected from patients were processed and embedded into Matrigel to generate PDOs. Parental PDOs with heterogenous morphology were sorted to isolate clonal pure morphology organoids. Multiple clones were expanded and clones of different morphology were collected and dissociated to single cells for single-cell RNA sequencing. Multiple single morphology clones were grown from nine different mixed morphology parental PDOs, demonstrating that EAC organoids can be generated from single cells. Successful formation of organoids from single cells took between two to four weeks. The percentage of single cells successfully generating organoids was sample-dependent. Six clones of solid, cystic, budding or grape-like morphology from two PDOs have been expanded and dissociated to single cells for single-cell RNA sequencing. PDOs have emerged as a powerful tool to study drug response and personalize therapy. This study will examine the correlation of EAC organoid morphology with gene expression. Future directions will include the identification of morphology-dependent drug targets, enabling the development of more precise targeted drug screening for each patient.