Abstract 5033: Patient-derived xenograft screening in a three-dimensional tumor growth assay incorporating stromal elements to recapitulate the human tumor microenvironment
Authors: Jiang Simon , Wrigley Jane , Malhi Sumanjeet , Wood Jamie , Morton Stephanie , Wainwright Louise , Yin Yinfei , Kumari Rajendra 
Published: August 2018

Abstract
BACKGROUND: Pre-clinical tumour models lack human stromal cells and are inadequate for the assessment of novel tumour microenvironment targeted therapies. An increase in combination opportunities requires a higher throughput in vitro assay that utilised the patient relevant model. The 3D-tumour growth assay (3D-TGA) enables patient-derived tumour cells to be admixed with a basement membrane extract and bone marrow-derived mesenchymal stem cells (bmMSCs) in a 96-well format for screening. Response to standard of care (SoC) agents such as paclitaxel, targeted agents such as Erlotinib were compared to subcutaneous xenograft responses in vivo. METHODS: Tumour cells or xenograft material which is disaggregated to yield a pure epithelial population, are admixed and suspended in basement membrane extract (Cultrex®, Trevigen) with and without bmMSCs. Cells were maintained for three days before they were treated with a panel of test agents, such as paclitaxel, AZD2014, Erlotinib, carboplatin for lung PDX and final cell viability was determined on day 7 by alamar blue assay. IC50 curves were determined using GraphPad Prism 6.0. Subcutaneous tumour growth was evaluated three times a week by measuring the tumour in two dimensions using electronic callipers for the duration of the study and tumour volumes were estimated using length and width measurements. Treatment was initiated when tumour growth was established. RESULTS: A panel of PDX models which contain various mutation sites (e.g. EGFR, KRAS) were assessed with a range of SoC (e.g. carboplatin, pemetrexed and paclitaxel) or targeted agents (e.g. Erlotinib, AZ2014). A squamous NSCLC model LU6422, which harbours a heterozygous mutation in the EGF-R intracellular kinase domain (c.2573T&gt;G (L858R)) showed exquisite sensitivity to Erlotinib in both 3D TGA and xenograft studies. Similarly, a squamous NSCLC model LU6402 was assessed with AZD2014 and Paclitaxel in 3D-TGA in the presence of bmMSCs which showed an additive effect of AZD2014 in combination of Paclitaxel on tumour cell growth. A similar efficacy was observed in subcutaneous in vivo xenograft; however, a combination finding was not evident when the stromal cells bmMSCs were absent. The data illustrates that the comparable sensitivities to various test agents between 3D-TGA and in vivo xenograft studies was observed. CONCLUSIONS: The 3D tumour growth assay fast and simple approach to restoring the interaction between the tumour and stroma in a 96-well format enabling screening to multiple dug concentrations and combinations. This assays provide unique opportunity for interrogating therapies that target the tumour microenvironment using patient relevant models.
Citation Format: Simon Jiang, Jane Wrigley, Sumanjeet Malhi, Jamie Wood, Stephanie Morton, Louise Wainwright, Yinfei Yin, Rajendra Kumari. Patient-derived xenograft screening in a three-dimensional tumor growth assay incorporating stromal elements to recapitulate the human tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5033.