A Novel Patient Derived Orthotopic Xenograft Model Of Gastro-Esophageal Junction Cancer: Key Platform For Translational Discoveries.

64Background: Mouse models of gastroesophageal junction (GEJ) cancer strive to recapitulate the intratumoral heterogeneity and cellular crosstalk within patient tumors to improve clinical translation. Current GEJ models have limited applications in tumor microenvironment, immune oncology and metastatic studies. Methods: A novel patient derived tumor orthotopic xenograft (PDOX) was established from GEJ cancer via surgical implantation. Patient tumor was compared to subcutaneously implanted PDX and PDOX by Hu0026E, IHC, and next generation sequencing (T200.1 panel). Drug efficacy studies of 5-flurouracil with and without radiotherapy are being performed. Results: Mechanical abrasion of mouse GEJ prior to implantation of patient derived tumor in situ promotes tumor engraftment (100%, n = 6). Complete PDOX engraftment was observed with rapid intra and extra luminal tumor growth as evidenced by MRI. Patient derived stroma co-engrafts with tumor cells in GEJ-PDOX. PDOXs contain fibroblasts, immune and inflammatory ...