Abstract 2815: Patient derived orthotopic xenograft (PDOX) model developed from needle biopsy specimen replicated clinical outcomes in advanced pancreatic cancer

Introduction: A patient-derived xenograft (PDX) as a preclinical model can reflect the pathological and molecular features and drug responsibility of a patient’s tumor. PDXs have been generated by subcutaneously implanting surgically resected tumor fragments into immunodeficient mice. Unfortunately, 80 % of pancreatic cancer patients is unresectable and they show highly aggressive and metastatic tumors. In most cases, diagnoses are confirmed histologically and diagnosed through endoscopic ultrasonography-guided/fine-needle aspiration (EUS/FNA) or percutaneous liver biopsy. However, they are not suitable for subcutaneous implantation into mice due to their threadlike shape and very small size. Therefore, the lack of patient-derived model system in pancreatic cancer is in desperate need of new strategy to cover unresectable patients as well as resectable. Here, we pioneered the development of a unresectable patient-derived orthotopic xenograft (PDOX) model satisfied with short period and high success rate, and made the best use of them as the test model for drug response. Methods and Results: PDOX models were established with a technique of direct surgical orthotopic implantation into the pancreatic tail of Athymic nude mice. PDOX models using fine needle biopsy had a higher success rate of engraftment, nearly 40% (17 cases among 44 cases) in patients with a time to progression of