The in vitro cytotoxicity assay using the human hepatocellular carcinoma (HepG2) cell line is a widely-used screen for the both the detection of hepatotoxic potential and the identification of detrimental pharmacological activities associated with a candidate drug. A retrospective attrition analysis at Takeda showed that only 31% of internal candidate drugs that displayed adverse findings in an in vivo toxicity study at low doses (Total Cmax &lt; 10uM) were cytotoxic against the HepG2 cell line. To understand the value of additional or replacement cytotoxicity assays towards the prediction of low-dose in vivo toxicity, we evaluated five types of primary human cells against 117 internal candidate compounds with in vivo toxicity data. Our results indicate that primary human hepatocytes and HUVECs are the most sensitive (hit rates 41% and 44%, respectively) when compared to HepG2 (hit rate 26%). However, these cells were less specific than HepG2 towards the prediction of compounds known to have toxic findings below the Cmax level of 10uM. This may limit their impact in early drug discovery where high specificity is valued so that compounds are not unnecessarily deprioritized. Primary cells may be more sensitive to specific pharmacological activities, as opposed to mechanisms associated with cell health, and a deeper investigation into the type of toxicity observed may be necessary to fully understand the value of these assays. Nevertheless, both primary hepatocytes and HUVECs may be useful to follow up the event of a negative response in the HepG2 assay. In this case, primary cells may be able to differentiate undesirable off-target pharmacology and metabolism profiles of lead compounds within the same chemotype. Case studies of recent projects at Takeda will be presented to support this conclusion as well as the activity profiles of these assays against the compounds in the dataset.

Evaluating the value of primary human cells for the prediction of in vivo toxicity in early drug discovery

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.