Abstract 1880: High throughput screening of 30 PDX cell lines in a 3D ECM hydrogel platform, incorporating tumor, stroma and immune components to demonstrate simultaneous investigation of multiple anti-tumor modalities
Authors: Hribar Kolin C. , Xue Bin , Harrod Christopher , Jensen Timothy , Schüler Julia 
Published: June 2022

Abstract
High throughput screening offers tangible benefits towards rapidly testing various permutations of novel or existing therapeutic agents. In particular, tumor panels that cover a range of histotypes and molecular subtypes have been previously developed, such as the NCI-60, however they utilize cell lines and, in some cases, a 2D cell culture format, which limit their translatability to preclinical and clinical trials. Moreover, the biological complexity of the tumor microenvironment (TME) has revealed a need for more translatable 3D in vitro tumor models that reflect the in vivo physiological outcome to therapies, particularly with the explosion of immunotherapy programs in drug discovery which target the immune compartment of the TME. Here, we describe for the first time a 3D in vitro PDX panel comprising 30 distinct PDX models in coculture with fibroblasts and PBMCs in engineered extracellular matrix hydrogels that display distinct similarities to the three compartments of the TME - tumor, stroma, and immune cells. Histotypes in the panel include, amongst others, Non-small cell lung, colorectal, breast, pancreatic, gastric, melanoma, and renal cancers. The panel is constructed in a high throughput 96-well format and rapidly assays tumor growth delay and other endpoints such as apoptosis in a dose-dependent manner across various drug modalities such as small molecules, biologics and cell therapy. The panel has been tested against targeted therapy (Docetaxel, Cisplatin) and immunomodulatory agents (Pembrolizumab, Atezolizumab) and the results correlate to the corresponding PDX in vivo data. Interestingly, cisplatin treatment displayed an average size reduction of &gt;30% for melanoma but a varied response in NSCLC tumors. And, several NSCLC responded more favorably to checkpoint inhibitors, however, the lung epidermoid PDX demonstrated no significant response. Moreover, subsequent cytokine analysis and immunofluorescence staining of several models revealed protein signatures of cancer-associated fibroblasts and CD3+ sequestration in the tumor stroma in some 3D models, suggesting the fibroblasts’ critical role in regulating the immune response. In short, the 30-PDX Panel described here represents a large step forward towards achieving translatable efficacy data at the earliest stages of drug discovery where little is known about the mechanism of action for a particular therapeutic agent or combination of agents.
Citation Format: Kolin C. Hribar, Bin Xue, Christopher Harrod, Timothy Jensen, Julia Schüler. High throughput screening of 30 PDX cell lines in a 3D ECM hydrogel platform, incorporating tumor, stroma and immune components to demonstrate simultaneous investigation of multiple anti-tumor modalities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1880.