Synergistic Cytotoxicity from Drugs and Cytokines In Vitro as an Approach to Classify Drugs According to Their Potential to Cause Idiosyncratic Hepatotoxicity: A Proof-of-Concept Study

Abstract

Idiosyncratic drug-induced liver injury (IDILI) typically occurs in a small fraction of patients and has resulted in removal of otherwise efficacious drugs from the market. Current preclinical testing methods are ineffective in predicting which drug candidates have IDILI liability. Recent results suggest that immune mediators such as tumor necrosis factor- (TNF) and interferon- (IFN) interact with drugs that cause IDILI to kill hepatocytes. This proof-of-concept study was designed to test the hypothesis that drugs can be classified according to their ability to cause IDILI in humans using classification modeling with covariates derived from concentration-response relationships that describe cytotoxic interaction with cytokines. Human hepatoma (HepG2) cells were treated with drugs associated with IDILI or with drugs lacking IDILI liability and cotreated with TNF and/or IFN. Detailed concentration-response relationships were determined for calculation of parameters such as the maximal cytotoxic effect, slope, and EC for use as covariates for classification modeling using logistic regression. These parameters were incorporated into multiple classification models to identify combinations of covariates that most accurately classified the drugs according to their association with human IDILI. Of 14 drugs associated with IDILI, almost all synergized with TNF to kill HepG2 cells and were successfully classified by statistical modeling. IFN enhanced the toxicity mediated by some IDILI-associated drugs in the presence of TNF. In contrast, of 10 drugs with little or no IDILI liability, none synergized with inflammatory cytokines to kill HepG2 cells and were classified accordingly. The resulting optimal model classified the drugs with extraordinary selectivity and specificity.

Betulinic Acid Exerts Cytoprotective Activity on Zika Virus-Infected Neural Progenitor Cells

“…The fact that BA at the maximum concentration tested (50 µM) is not toxic to uninfected NPCs but promoted a significant cell loss in ZIKV-infected cultures, suggests a cytotoxic interaction between BA and ZIKV-induced factors. In this regard, synergistic cytotoxicity from drugs and cytokines have been previously described ( Maiuri et al., 2017 ; Olmo et al., 2017 ). Indeed, it has been demonstrated that ZIKV infection is capable of triggering the production of proinflammatory cytokines, such as TNF and IL-β, and glutamate, mediators shown to induce neuronal cell death in ZIKV ( Olmo et al., 2017 ).…”

Beyond Metabolism: Role of the Immune System in Hepatic Toxicity

“…Many drugs associated with IDILI do not kill hepatocytes in vitro at clinically relevant concentrations; however, they become cytotoxic in the presence of nontoxic concentrations of TNFa and/or IFNg. [120][121][122][123] This synergy occurs in isolated murine and human hepatocytes as well as in transformed human hepatocytes (HepG2 cells). We hypothesized that these drugs induce cellular stress in hepatocytes, rendering the cells vulnerable to killing by cytokines.…”

“…Trovafloxacin was only cytotoxic to hepatocytes in vitro in the presence of TNF. 121,123 In HepG2 cells, treatment with trovafloxacin led to DNA strand breaks, inhibition of cell division, and replication stress, presumably due to inhibition of topoisomerase II. 124,125 The trovafloxacin-induced DNA damage was greater in magnitude and occurred earlier in the presence of TNFa, although TNFa alone was without effect.…”

Predictivity/Translatability of Toxicities Observed in Nonclinical Toxicology Studies to Clinical Safety Outcomes in Drug Development: Case Examples

“…Based on this hypothesis, we undertook a proof-of-concept study to determine whether drug-TNF interaction in vitro could classify drugs according to their IDILI liability. 35 We exposed the human hepatocyte cell line, HepG2, to various drugs in the presence and absence of TNF and elucidated detailed concentration-response curves, with cytotoxicity (lactate dehydrogenase release) as the sole end point. Our initial study employed 14 drugs that have been associated with human IDILI and 10 that have had little or no IDILI association.…”