PI-081 - ELEXACAFTOR/TEZACAFTOR/IVACAFTOR (ETI) -INDUCED REACTIVE OXYGEN SPECIES (ROS) PRODUCTION IN HEPG2 CELLS: A POTENTIAL MECHANISM OF DRUG-INDUCED LIVER INJURY (DILI)

A. Shi, P. Beringer; University of Southern California, Los Angeles, CA, USA.

Background: The introduction of elexacaftor/tezacaftor/ivacaftor (ETI) has significantly improved lung function and nutritional status for nearly 90% of people with cystic fibrosis (CF). However, 6% of individuals receiving ETI experience elevations in hepatic transaminases > 3 times the upper limit of normal and several cases of DILI have been reported including a case resulting in fulminant hepatic failure requiring a liver transplantation. The precise mechanism(s) involved in ETI-mediated DILI are currently unknown. We aim to uncover the mechanisms of DILI caused by ETI, including the effect on ROS production, mitochondrial respiration, and bile acid transport.

Methods: HepG2 cells were incubated for 24 hours with either elexacaftor (ELX), tezacaftor (TEZ), or ivacaftor (IVA) in a range of concentrations, and stained with dihydroethidium (a fluorescent indicator of ROS). The fluorescence level was captured using the Cytation 5 imager, and the mean cell-count-normalized fluorescence intensity was calculated for each ETI compound concentration to determine relative ROS levels. Experiments investigating the effect of ETI on mitochondrial respiration and bile acid transport are underway.

Results: ROS levels for IVA and TEZ increased in a dose-dependent manner. The highest IVA concentrations, 10 µM and 25 µM, had ROS levels significantly above the negative control baseline (0.2% DMSO vehicle) by 1.5x (P = 0.0419) and 2.4x (P = 0.0002), respectively. The highest TEZ concentration, 10 µM, had ROS levels significantly above baseline by 1.4x (P = 0.0140). ROS levels for all ELX concentrations were not significantly different from baseline.

Conclusion: IVA and TEZ increase ROS production in HepG2 cells and provide a potential mechanistic basis for ETI-induced DILI in people with CF.