Abstract 5786: Histopathology of patient derived organoids for the quantitative analysis of response to microenvironmental perturbations
Authors: Choung Sarah J. , Spiller Erin , Lau Roy , Mumenthaler Shannon 
Published: July 2017

Abstract
Patient derived organoids are becoming a popular 3D in vitro model that more accurately recapitulate in vivo conditions compared to standard 2D culture systems. Organoids consist of epithelial cells and lack stroma and mesenchyme, allowing cells of interest to be studied as an isolated system. However, the tunability of the organoid model also permits the re-addition of microenvironmental factors, i.e. cancer associated fibroblasts (CAFs), resulting in a wide range of experimental capabilities. Organoids are easily scalable, making them more efficient and cost-effective than traditional animal models. Despite the popularity of animal models for pre-clinical drug testing, there still remain issues with translating results from animal testing to patient outcomes; even patient-derived xenograph models experience non-physiological mouse-human interactions. Therefore, studying the impact of microenvironmental perturbations, such as the presence of CAFs, or nutrient and drug gradients, on organoids may reduce translational error. Using our biorepository of patient derived colon cancer (primary and liver metastases) organoids, we can observe changes in tumor architecture and cell growth or death, allowing us to more accurately assess the efficacy of drug therapies and observe how interpatient heterogeneity impacts their efficacy. Here we focus on the histopathology of different patient derived organoids to quantitatively study cell growth or death under drug treatments (+/- CAFs) which could ultimately become a standard procedure for drug screening.
Here we investigate the effects of CAF co-culture in patient derived organoids in response to standard chemotherapies such as Irinotecan and Oxaliplatin. Following treatment, the organoids are paraffin fixed to retain their structural integrity, then sectioned. The samples are stained with H&E to show the tumor architecture, and immunofluorescent antibodies (IF) to identify cells that are proliferating (Ki67) or apoptotic (TUNEL). As a result, we are able to investigate how tumor microenvironmental factors affect the tumor architecture of an individual patient tumor. We also examine the cytotoxic or cytostatic effects of standard chemotherapies by quantitating the number of proliferative and apoptotic cells, as well as their location within the tumor, in response to the presence of both CAFs and therapy.
Ultimately, we envision the method outlined here will further personalize medicine by allowing physicians to more rapidly assess an individual patient’s response to therapy and adjust treatment accordingly. Additionally, this method could prove to be a more inexpensive and faster means of screening new drug compounds. By creating a system that more closely recapitulates patient outcomes, we hope to move therapies towards faster approval while still retaining results representative of in vivo outcomes.
Citation Format: Sarah J. Choung, Erin Spiller, Roy Lau, Shannon Mumenthaler. Histopathology of patient derived organoids for the quantitative analysis of response to microenvironmental perturbations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5786. doi:10.1158/1538-7445.AM2017-5786