An Organoid/Immune Cell Co‐Culture as a Predictive Model for the Treatment of Pancreatic Cancer

Abstract

BackgroundDue to late stage diagnosis and resistance to chemotherapy, pancreatic ductal adenocarcinoma (PDAC) has the lowest five‐year survival rate of all cancers in the United States. Programmed death 1 receptor (PD1)‐programmed death ligand 1 (PD‐L1) immune checkpoint inhibition is found to be unsuccessful in clinical trials. Myeloid derived suppressor cells (MDSCs) are found to be in high abundance in the pancreatic cancer microenvironment.HypothesisElevated infiltration of granulocytic (G)‐MDSCs within the PDAC tumor microenvironment inhibit T cell effector function regardless of anti‐PD1 immunotherapy.MethodsPDAC organoids were generated from C57BL/6 mice orthotopically transplanted with 7940B pancreatic cancer cells, or patient resected tumors. CD8+ cytotoxic T lymphocytes (CTLs) were extracted from mouse spleens. Dendritic cells and monocytes were extracted from mouse bone marrow. CTLs, dendritic cells and monocytes were extracted from the patient whole blood. Mouse and human pancreatic cancer organoids were co‐cultured with autologous immune cells. Co‐cultures were treated with anti‐PD1 therapy, standard‐of‐care chemotherapeutics (gemcitabine and abraxane) and MDSC inhibitor cabozantinib (cabo). In a separate series of experiments, C57BL/6 mice purchased from Jackson Laboratories were orthotopically transplanted with 7940B pancreatic cancer cells. Seven days post‐transplantation, mice were treated with chemotherapeutics, Nivolumab (PD‐1 neutralizing antibody), cabo or a combination of 2 or 3 of these drugs for a further 7 days. Tumor tissue was analyzed for changes in weight and size using 18F‐FDG PET/CT imaging, and infiltration of MDSCs and PD‐L1‐expressing cells by flow cytometry.ResultsMice that developed high grade pancreatic cancer and patients with advanced stage PDAC had an increased infiltration of G‐MDSCs. In vivo, mice with tumors did not respond to anti‐PD1 therapy even in combination with chemotherapy. The co‐administration of cabozantinib resulted in significantly smaller tumors. Mouse‐derived pancreatic cancer organoid/CTL/MDSC co‐cultures treated with anti‐PD1 therapy exhibited low CTL cell proliferation that correlated with PD‐L1‐expressing organoid cell survival. Depletion of MDSCs from culture induced CTL proliferation and organoid death. Human‐derived organoid/immune cell co‐culture responses to therapy correlated with the patient's immune phenotype within tumor tissue and patient prognosis.ConclusionWe report a pre‐clinical model that may predict the efficacy of targeted therapies to improve the outcome of patients.Support or Funding InformationGoldman Grant (Zavros, University of Cincinnati) F31DK120206 (Holokai) Ohio Physiological SocietyThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.