HepG2 (C3A) spheroids show higher sensitivity compared to HepaRG spheroids for drug-induced liver injury (DILI)

High-throughput, automation-friendly and therapeutically-predictive assays are needed in early drug discovery in order to prioritise compounds and reduce the risk of new drugs causing Drug-Induced Liver Injury (DILI). We evaluated the suitability of high-throughput 3D liver spheroid models of HepG2 (C3A clone) and HepaRG cell lines to predict DILI in early drug development. Spheroids were formed in 384-well ultra-low-attachment plates and dosed via direct acoustic droplet ejection at nine half-log spaced concentrations per compound. Spheroid viability was quantified with an ATP endpoint after a 4-day incubation with 150 drugs with known DILI liability. We derived a margin of safety for each cell line defined as the ratio between the IC₅₀ values generated for each compound to their maximum plasma concentration C_max which resulted in optimal classification accuracy. The margin of safety can be used to estimate a maximum safe C_max for compounds in early drug discovery for which C_max is not yet known. Both cell lines had similar level of accuracy in predicting DILI, with HepG2 spheroids being more sensitive. HepG2 spheroids had a sensitivity of 58% and a specificity of 83%, while HepaRG spheroids had a sensitivity of 47% and specificity of 86%. Ninety-nine of the 150 compounds were used to compare the relative sensitivities of HepG2 and HepaRG spheroids. HepaRG spheroids were more sensitive to 7 compounds and HepG2 spheroids were more sensitive to 34 compounds. In conclusion, across a diverse group of drugs HepG2 spheroids were more predictive of DILI compared to HepaRG spheroids.