Establishment of Pancreatic Tumor Organoid Models for Drug Evaluation
Pancreatic ductal adenocarcinoma (PDAC), the main form of pancreatic cancer, is the most lethal type of maligancy with five-year survival rate of ~7%, mainly due to the lack of early detection and effective treatments. To facilitate discovery of new therapeutics for PDAC, experimental models that can accurately reflect the characteristics of PDAC are needed. While 2-D cell lines and animal models such as genetically modified mouse models and mouse xenograft models are all widely used in PDAC drug development studies, they have significant drawbacks. For instance, 2-D cell cultures are unable to fully depict the heterogeneity and cell-cell interactions of natural PDAC tumors. The animal models can closely recapitulate the human PDAC but they are expensive and time consuming and therefore not amenable to high throughput assays.
Patient tumor derived organoids have recently emerged as a valuable research tool due to their resemblance to natural tumor tissues, with a 3-D structure and heterogeneous populations of cells. In this study, we sought to establish a protocol for establishing organoid models from mouse and human PDAC tissues for evaluation of investigational drugs. Single cell suspensions were first obtained from a KPC mouse tumor by mechanical and enzymatic dissociation. The cells were then mixed with Matrigel and plated into cell culture plates to form organoids. The resulting organoids were fixed, imbedded into paraffin, and stained with hematoxylin and eosin (H&E) to examine their histological features. The morphology of the organoids resembles the features of mouse and human PDAC very closely. The organoids were then used to test the antitumor activity of agents, TP0903, dBET6, CPI-0610, that are currently under investigation for potential treatment of PDAC using a cell growth assay. The IC50 of the three agents in the organoid model are 3.10, 2.17, >10 µM, respectively. These outcomes were then compared to those of 2-D cell cultures grown from the same tumor. Organoids were found to be much less sensitive towards those agents than 2-D cells with IC50 values of 1.76, .81, >10 µM, respectively.
The present study is a significant step towards developing organoid models as a tractable system for PDAC research and drug development. Further exploration will be done on establishing organoids from PDAC patients’ tumors and testing their sensitivity to different therapeutics to help the selection of treatment for individual patients (i.e. personalized therapy).