Abstract A139: The use of multi-species organoids as tools to assess cancer therapy induced intestinal toxicity

The mouse intestinal organoid model was first described 10 years ago and has been adopted as a tool assay for several disease indications and treatments, including cancers. Gastrointestinal (GI) toxicity is a common and often severe dose limiting side effect of both conventional chemotherapy and the more recent ‘targeted’ therapies that cause adverse ‘off tissue’ responses. Symptoms often include diarrhoea, dehydration and ulceration, leading to increased susceptibility to infection, due in part to impaired barrier function as a result of damage to the crypt and/or villus structures. As improvements in oncology therapeutics are pursued to acquire more efficacious agents, assessment of their potential GI toxicity remains crucial. We have further developed and validated the organoid model as a screening tool to predict GI toxicity and subsequent mucosal regeneration in order to assess both comparative species toxicities (mouse, rat, dog and human) and the underlying pathways that are affected. All culture conditions are designed to mimic the stem cell niche and allow cell differentiation and proliferation to occur. Agents screened to-date include Wnt pathway regulators, cytokines, growth factors, chemotherapy drugs, steroids and lectins. The toxic effects of irradiation have also been measured. For the assay, intestinal crypts were isolated using chelating agents and cultured in media adapted from that described by Sato et al in 2009. Organoids were broken into fragments, plated into multi-well plates in the presence of test drugs. Levels of toxicity associated with conventional chemotherapy agents such as Oxaliplatin, 5-Fluorouracil, CPT-11 and SN38 were determined by calculation of IC50 values. For routine IC50 assays the number of dead, unbranched and branched organoids were counted and presented as percentage viable and viable branched organoids. The total viable cell number was measured using a colorimetric cell proliferation assay or via live imaging. These values were then compared between species to inform on species sensitivity. Data was shown to highly correlate with published data on in vivo toxicity within the four species. Proof of concept gene expression data was also generated by both microarray and RNASeq to demonstrate the affected pathways. These were also linked to in vivo gene expression profiling and histopathology to demonstrate PD linkages – an example being recapitulation of induced Goblet cell hyperplasias. Specific changes in stem cell number were also assessed using in situ hybridisation via RNAscope to visualise the Lgr5 positive cell number and location before and after treatment. We conclude that organoids are a predictive preclinical model that can be used to identify any potential on-target, off-tissue GI toxicities induced by novel oncology therapeutics. Toxicity and mechanism of action can all be addressed in vitro to potentially reduce in vivo experimentation. Citation Format: Valentina Ubertini, Sarah Hoyle, Aude-Marine Bonavita, Francesca Phillips, Alan Murdoch, Nicola Tonge, Cath Booth. The use of multi-species organoids as tools to assess cancer therapy induced intestinal toxicity [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A139. doi:10.1158/1535-7163.TARG-19-A139