DiscussionAuthor: Maria Twardowska
Affiliates: Malcolm Haddrick, Clare Sefton,Thierry Dorval, Yinhai Wang, Abhishek Srivastava, Claire Summers, Alison Foster, Derrick Morgan.
At AstraZeneca, as many as 60% of projects fail due to safety related attrition with hepatotoxicity being the second leading cause. It is therefore crucial to develop predictive screens at the earliest stages of drug discovery to influence chemistry design, ensure patient safety, reduce animal use and improve resource investment. In this project a novel cell technology called Upcyte® hepatocytes developed
by Medicyte GmbH was assessed for its competence to detect hepatotoxins
to screening scale. Upcytes® are primary human hepatocytes genetically engineered to have higher proliferative potential as well as maintaining phenotypic and functional hepatic characteristics such as cytochrome (CYP) enzyme expression, urea
and glycogen production. First, the optimal culture conditions were established for the 3 purchased donors: 422A-03, 153-03, 653-03. Upcytes® were then exposed to known drug-induced liver injury (DILI) compounds, the same reference set as used by the Innovative Medicine Initiative group (MIP-DILI) consortia. Initially, assay conditions were established in 2D 384-well plate format with 73 DILI compounds being tested at 24 and 72 hours. These results showed variability in response and without any significant increase in predictivity compatred to existing models. Therefore, studies progressed to a 3D format with generation of Upcyte® hepatocyte spheroids to enable 2D to 3D comparison and assessment of any predictivity advantage. Donor-to-donor specificity was observed in phenotypic and functional features such as spheroid formation, size measurements and hepatotoxic compound detection. The performance of upcyte spheroids was compared to data from human hepatic carcinoma HepG2 C3A cell line spheroids and primary human hepatocytes (Insphero). Upcytes were only able to detect 4 out of 14 hepatotxic compounds as compared to 7 for C3As and 8 for PHH. Further experiments assessed the consequences of generating mixed upcyte-C3A spheroids in various percentage combinations and exposure of these to the same compound set.
Key words: drug safety screening, hepatotoxicity, DILI, upcyte hepatocytes, spheroids