Development and Validation of a Test to Identify Drugs That Cause Idiosyncratic Drug-Induced Liver Injury

Decreased Hepatic Functional Reserve Increases the Risk of Piperacillin/Tazobactam-Induced Abnormal Liver Enzyme Levels: A Retrospective Case-Control Study

BACKGROUND

Piperacillin/tazobactam (PIPC/TAZ), which is a combination of a beta-lactam/beta-lactamase inhibitor, often causes liver enzyme abnormalities. The albumin-bilirubin (ALBI) score is a simple index that uses the serum albumin and total bilirubin levels for estimating hepatic functional reserve. Although patients with low hepatic reserve may be at high risk for drug-induced liver enzyme abnormalities, the relationship between PIPC/TAZ-induced abnormal liver enzymes levels and the ALBI score remains unknown.

OBJECTIVE

This study aimed to elucidate the relationship between PIPC/TAZ-induced abnormal liver enzyme levels and the ALBI score.

METHODS

This single-center retrospective case-control study included 335 patients. The primary outcome was PIPC/TAZ-induced abnormal liver enzyme levels. We performed COX regression analysis with male gender, age (≥75 years), alanine aminotransferase level (≥20 IU/L), and ALBI score (≥-2.00) as explanatory factors. To investigate the influence of the ALBI score on the development of abnormal liver enzyme levels, 1:1 propensity score matching between the ≤-2.00 and ≥-2.00 ALBI score groups was performed using the risk factors for drug-induced abnormal liver enzyme levels.

RESULTS

The incidence of abnormal liver enzyme levels was 14.0% (47/335). COX regression analysis revealed that an ALBI score ≥-2.00 was an independent risk factor for PIPC/TAZ-induced abnormal liver enzyme levels (adjusted hazard ratio: 3.08, 95% coefficient interval: 1.207-7.835, P = 0.019). After 1:1 propensity score matching, the Kaplan-Meier curve revealed that the cumulative risk for PIPC/TAZ-induced abnormal liver enzyme levels was significantly higher in the ALBI score ≥-2.00 group (n = 76) than in the <-2.00 group (n = 76) (P = 0.033).

CONCLUSION AND RELEVANCE

An ALBI score ≥-2.00 may predict the development of PIPC/TAZ-induced abnormal liver enzyme levels. Therefore, frequent monitoring of liver enzymes should be conducted to minimize the risk of severe PIPC/TAZ-induced abnormal liver enzyme levels in patients with low hepatic functional reserve.

Hepatotoxicity of Antibiotics and Antifungals and Their Safe Use in Hepatic Impairment

Idiosyncratic drug-induced liver injury (DILI) is a rare and unpredictable form of hepatotoxicity. While its clinical course is usually benign, cases leading to liver transplantation or death can occur. Based on modern prospective registries, antimicrobials including antibiotics and antifungals are frequently implicated as common causes. Amoxicillin-clavulanate ranks as the most common cause for DILI in the Western World. Although the absolute risk of hepatotoxicity of these agents is low, as their usage is quite high, it is not uncommon for practitioners to encounter liver injury following the initiation of antibiotic or antifungal therapy. In this review article, mechanisms of hepatoxicity are presented. The adverse hepatic effects of well-established antibiotic and antifungal agents are described, including their frequency, severity, and pattern of injury and their HLA risks. We also review the drug labeling and prescription guidance from regulatory bodies, with a focus on individuals with hepatic impairment.

Drug interference with biochemical laboratory tests

Clinical laboratory practice represents an essential part of clinical decision-making, as it influences 60-70% of medical decisions at all levels of health care. Results of biochemical laboratory tests (BLTs) have a key role in establishment of adequate diagnosis as well as in evaluation of treatment progress and outcome. The prevalence of drug-laboratory test interactions (DLTIs) is up to 43% of patients who had laboratory results influenced by drugs. Unrecognized DLTIs may lead to misinterpreted BLTs results, incorrect or delayed diagnosis, extra costs for unnecessary additional tests or inadequate therapy, as all may cause false clinical decisions. The significance of timely and adequate recognition of DLTIs is to prevent common clinical consequences such as incorrectly interpreted test results, delayed or non-treated condition due to erroneous diagnosis or unnecessary extra tests or therapy. Medical professionals should be educated that it is essential to obtain patient data about medications especially for the drugs used in the last 10 days before biological material collection. Our mini-review aims to provide a comprehensive overview of the current state in this important domain of medical biochemistry with detailed analysis of the effect of drugs on BLTs and to give detailed information to medical specialists.

Acute and sub-acute toxicity evaluation of Merremia tridentata (L.) stem extract on mice

The acute and sub-acute toxicity studies were performed in male and female Swiss albino mice as per the guidelines mentioned in OECD. The oral administration of M. tridentata stem extract (MSE) showed no treatment-related mortality and body weight change in mice up to the single dose of 30,000 mg/kg body weight in the acute toxicity study and up to a dose of 30,000 mg/kg/day body weight in the sub-acute toxicity study. Moreover, the clinical signs, body weight, gross pathology, organ weight, hematology (except for platelet count), biochemical analysis, and histopathology did not show significant variation at a medium dose of 15,000 mg/kg/day body weight compared to the control group. However, toxicological signs in behavior, very mild interstitial nephritis, as well as significant variation in platelet count and total protein parameters were observed at a dose of 30,000 mg/kg/day in the 28-day oral toxicity study. Thus, the no-observed-adverse-effect level was determined at a dose of 15,000 mg/kg/day body weight. Based on study results, it is concluded that MSE showed LD₅₀ of greater than 5000 mg/kg/day body weight. Hence, this could be a potential candidature as a future safe pharmaceutical product.

Immunostimulatory activity and structure-activity relationship of epimedin B from Epimedium brevicornu Maxim

Epimedii Folium (EF, Epimedium brevicornu Maxim.), a traditional botanical drug, is famous for treating bone fractures, joint diseases, and several chronic illnesses. However, some studies indicated that EF could induce idiosyncratic drug-induced liver injury (IDILI) in the clinic. The NLRP3 inflammasome plays a crucial role in the pathogenesis of various human diseases, including IDILI. In the present study, we showed that epimedin B could specifically facilitate nigericin- or ATP-induced NLRP3 inflammasome activation under synergistic induction of mitochondrial reactive oxygen species. Moreover, epimedin B resulted in activation of Caspase-1 and IL-1β secretion in a lipopolysaccharide (LPS)-mediated susceptibility mouse model. MCC950 pretreatment completely abrogated activation of the NLRP3 inflammasome and prevented liver injury. Importantly, several studies have confirmed that some active constituents of EF could enhance activation of the NLRP3 inflammasome and may be involved in the pathogenesis of EF-IDILI. No reports are available on whether the structure-activity relationship associated with the immunostimulatory activity in EF contributes to the pathogenesis of EF-IDILI. These findings have changed our conventional understanding about the more glycogen, the more immunostimulatory activity.

A novel quantitative computer-assisted drug-induced liver injury causality assessment tool (DILI-CAT)

Background and aims

We hypothesized that a drug’s clinical signature (or phenotype) of liver injury can be assessed and used to quantitatively develop a computer-assisted DILI causality assessment-tool (DILI-CAT). Therefore, we evaluated drug-specific DILI-phenotypes for amoxicillin-clavulanate (AMX/CLA), cefazolin, cyproterone, and Polygonum multiflorum using data from published case series, to develop DILI-CAT scores for each drug.

Methods

Drug specific phenotypes were made up of the following three clinical features: (1) latency, (2) R-value, and (3) AST/ALT ratio. A point allocation system was developed with points allocated depending on the variance from the norm (or “core”) for the 3 variables in published datasets.

Results

The four drugs had significantly different phenotypes based on latency, R-value, and AST/ALT ratio. The median cyproterone latency was 150 days versus < 43 days for the other three drugs (median: 26 for AMX/CLA, 20 for cefazolin, and 20 for Polygonum multiflorum; p<0.001). The R-value for the four drugs was also significantly different among drugs (cyproterone [median 12.4] and Polygonum multiflorum [median 10.9]) from AMX/CLA [median 1.44] and cefazolin [median 1.57; p<0.001]). DILI-CAT scores effectively separated cyproterone and Polygonum multiflorum from AMX/CLA and cefazolin, respectively (p<0.001). As expected, because of phenotypic overlap, AMX/CLA and cefazolin could not be well differentiated.

Conclusions

DILI-CAT is a data-driven, diagnostic tool built to define drug-specific phenotypes for DILI adjudication. The data provide proof of principle that a drug-specific, data-driven causality assessment tool can be developed for different drugs and raise the possibility that such a process could enhance causality assessment methods.

Diclofenac-Induced Cytotoxicity in Direct and Indirect Co-Culture of HepG2 Cells with Differentiated THP-1 Cells

Non-steroidal anti-inflammatory drugs (NSAIDs) such as diclofenac (DIC) frequently induce drug-induced liver injury (DILI). It is unclear whether macrophages such as M1 and M2 participate in NSAID-associated DILI; elucidating this relationship could lead to a better understanding of the detailed mechanism of DILI. We co-cultured human hepatoma HepG2 cells with M1 or M2 derived from human monocytic leukemia THP-1 cells to examine the roles of M1 and M2 in DIC-induced cytotoxicity. DIC was added to the direct or indirect co-cultures of HepG2 cells with M1 or M2 (HepG2/M1 or HepG2/M2, respectively) at cell ratios of (1:0, 1:0.1, 1:0.4, and 1:1). In both direct and indirect HepG2/M2 co-cultures (1:0.4), there was lower lactate dehydrogenase release compared with HepG2/M1 co-cultures. Other NSAIDs as well as DIC showed similar protective effects of DIC-induced cytotoxicity. There were only slight differences in mRNA levels of apoptosis- and endoplasmic reticulum stress-associated factors between M1 and M2 after DIC treatment, suggesting that other factors determined the protective effects of M2 on DIC-induced cytotoxicity. Levels of high mobility group box 1 (HMGB1) in the medium and the mRNA expression levels of HMGB1 receptors were different between M1 and M2 after DIC treatment. Increased HMGB1 concentrations and expression of toll-like receptor 2 mRNA in M1 were observed compared with M2 after DIC treatment. In conclusion, these results suggested that the HMGB1/TLR2 signaling axis can be suppressed in M2 but not M1, leading to the different roles of M1 and M2 in NSAID-induced cytotoxicity.

Prediction of biochemical nonresolution in patients with chronic drug-induced liver injury: A large multicenter study

BACKGROUND AND AIMS

To clarify high-risk factors and develop a nomogram model to predict biochemical resolution or biochemical nonresolution (BNR) in patients with chronic DILI.

APPROACH AND RESULTS

Retrospectively, 3655 of 5326 patients with chronic DILI were enrolled from nine participating hospitals, of whom 2866 underwent liver biopsy. All of these patients were followed up for over 1 year and their clinical characteristics were retrieved from electronic medical records. The endpoint was BNR, defined as alanine aminotransferase or aspartate aminotransferase >1.5× upper limit of normal or alkaline phosphatase >1.1× ULN, at 12 months from chronic DILI diagnosis. The noninvasive high-risk factors for BNR identified by multivariable logistic regression were used to establish a nomogram, which was validated in an independent external cohort. Finally, 19.3% (707 of 3655) patients presented with BNR. Histologically, with the increase in liver inflammation grades and fibrosis stages, the proportion of BNR significantly increased. The risk of BNR was increased by 21.3-fold in patients with significant inflammation compared to none or mild inflammation (p < 0.001). Biochemically, aspartate aminotransferase and total bilirubin, platelets, prothrombin time, sex, and age were associated with BNR and incorporated to construct a nomogram model (BNR-6) with a concordance index of 0.824 (95% CI, 0.798-0.849), which was highly consistent with liver histology. These results were successfully validated both in the internal cohort and external cohort.

CONCLUSIONS

Significant liver inflammation is a robust predictor associated with biochemical nonresolution. The established BNR-6 model provides an easy-to-use approach to assess the outcome of chronic DILI.

Challenges and Future of Drug-Induced Liver Injury Research-Laboratory Tests

Drug-induced liver injury (DILI) is a rare but potentially severe adverse drug event, which is also a major cause of study cessation and market withdrawal during drug development. Since no acknowledged diagnostic tests are available, DILI diagnosis poses a major challenge both in clinical practice as well as in pharmacovigilance. Differentiation from other liver diseases and the identification of the causative agent in the case of polymedication are the main issues that clinicians and drug developers face in this regard. Thus, efforts have been made to establish diagnostic testing methods and biomarkers in order to safely diagnose DILI and ensure a distinguishment from alternative liver pathologies. This review provides an overview of the diagnostic methods used in differential diagnosis, especially with regards to autoimmune hepatitis (AIH) and drug-induced autoimmune hepatitis (DI-AIH), in vitro causality methods using individual blood samples, biomarkers for diagnosis and severity prediction, as well as experimental predictive models utilized in pre-clinical settings during drug development regimes.

A novel phenotype-based drug-induced liver injury causality assessment tool (DILI-CAT) allows for signal confirmation in early drug development

BACKGROUND

Drug-induced liver injury (DILI) requires accurate case adjudication, with expert opinion being the current best practice.

AIM

We utilised a novel DILI causality assessment tool (DILI-CAT), which uses drug-specific liver injury phenotypes, to examine potential DILI in early phase ximelagatran clinical development.

METHODS

We conducted a retrospective analysis of liver injury events from four Stroke Prevention using an ORal Thrombin Inhibitor in Atrial Fibrillation (SPORTIF) trials, in which patients were randomised to receive oral ximelagatran or adjusted-dose warfarin. A stepwise process was used with iterative adjustments. The DILI phenotype was characterised by latency, R-value, and AST/ALT ratio. A scoring algorithm was applied to liver events to assess how closely the liver events matched the Interquatile-Range for the working phenotype for each of the three parameters.

FINDINGS

Data from 3115 patients included in the SPORTIF trials as above were available. The initial ximelagatran phenotype was developed based on five liver injury cases from the ximelagatran arm and was then validated against an additional eight cases (5 ximelagatran, 3 warfarin); in these eight cases, there was a statistically significant difference in the total DILI-CAT scores of the two drugs (p = 0.016) between ximelagatran and warfarin. Together, these ten ximelagatran cases generated a second, refined ximelagatran phenotype, which was validated against an additional 75 cases (53 ximelagatran/22 warfarin)-again with statistically significant different DILI-CAT ximelagatran vs. warfarin scores (p < 0.001).

CONCLUSION

DILI-CAT, a clinically intuitive, data-driven, computer-assisted scoring algorithm, is a useful tool for early detection of drug's hepatotoxicity in clinical drug development.

Preclinical models of idiosyncratic drug-induced liver injury (iDILI): Moving towards prediction

Idiosyncratic drug-induced liver injury (iDILI) encompasses the unexpected harms that prescription and non-prescription drugs, herbal and dietary supplements can cause to the liver. iDILI remains a major public health problem and a major cause of drug attrition. Given the lack of biomarkers for iDILI prediction, diagnosis and prognosis, searching new models to predict and study mechanisms of iDILI is necessary. One of the major limitations of iDILI preclinical assessment has been the lack of correlation between the markers of hepatotoxicity in animal toxicological studies and clinically significant iDILI. Thus, major advances in the understanding of iDILI susceptibility and pathogenesis have come from the study of well-phenotyped iDILI patients. However, there are many gaps for explaining all the complexity of iDILI susceptibility and mechanisms. Therefore, there is a need to optimize preclinical human in vitro models to reduce the risk of iDILI during drug development. Here, the current experimental models and the future directions in iDILI modelling are thoroughly discussed, focusing on the human cellular models available to study the pathophysiological mechanisms of the disease and the most used in vivo animal iDILI models. We also comment about in silico approaches and the increasing relevance of patient-derived cellular models.

Critical Review of Gaps in the Diagnosis and Management of Drug-Induced Liver Injury Associated with Severe Cutaneous Adverse Reactions

Drug-induced liver injury (DILI) encompasses the unexpected damage that drugs can cause to the liver. DILI may develop in the context of an immunoallergic syndrome with cutaneous manifestations, which are sometimes severe (SCARs). Nevirapine, allopurinol, anti-epileptics, sulfonamides, and antibiotics are the most frequent culprit drugs for DILI associated with SCARs. Interestingly, alleles HLA-B*58:01 and HLA-A*31:01 are associated with both adverse reactions. However, there is no consensus about the criteria used for the characterization of liver injury in this context, and the different thresholds for DILI definition make it difficult to gain insight into this complex disorder. Moreover, current limitations when evaluating causality in patients with DILI associated with SCARs are related to the plethora of causality assessment methods and the lack of consensual complementary tools. Finally, the management of this condition encompasses the treatment of liver and skin injury. Although the use of immunomodulant agents is accepted for SCARs, their role in treating liver injury remains controversial. Further randomized clinical trials are needed to test their efficacy and safety to address this complex entity. Therefore, this review aims to identify the current gaps in the definition, diagnosis, prognosis, and management of DILI associated with SCARs, proposing different strategies to fill in these gaps.

Biomarkers of idiosyncratic drug-induced liver injury (DILI) - a systematic review

INTRODUCTION

Idiosyncratic drug-induced liver injury (DILI) is an unpredictable event, and there are no specific biomarkers that can distinguish DILI from alternative explanations or predict its clinical outcomes.

AREAS COVERED

This systematic review summarizes the available evidence for all biomarkers proposed to have a role in the diagnosis or prognosis of DILI. Following a comprehensive search, we included all types of studies in humans. We included DILI cases based on any threshold criteria but excluded intrinsic DILI, commonly caused by paracetamol overdose. We classified studies into diagnostic and prognostic categories and assessed their methodological quality. After reviewing the literature, 14 studies were eligible.

EXPERT OPINION

Diagnostic studies were heterogeneous with regard to the study population and outcomes measured. Prognostic models were developed by integrating novel biomarkers, risk scores, and traditional biomarkers, which increased their prognostic ability to predict death or transplantation by 6 months. This systematic review highlights the case of need for non-genetic biomarkers that distinguish DILI from acute liver injury related to alternative etiology. Biomarkers with the potential to identify serious adverse outcomes from acute DILI should be validated in independent prospective cohorts with a substantial number of cases.

Marked Increase of Gamma-Glutamyltransferase as an Indicator of Drug-Induced Liver Injury in Patients without Conventional Diagnostic Criteria of Acute Liver Injury

<b><i>Introduction:</i></b> Clinically significant drug-induced liver injury (DILI) is defined by elevations of alanine aminotransferase (ALT) ≥5 times the upper limit of normal (ULN), alkaline phosphatase (ALP) ≥2 × ULN, or ALT ≥3 × ULN and total bilirubin TBIL &#x3e;2 × ULN. However, DILI might also occur in patients who do not reach those thresholds and still may benefit from discontinuation of medication. <b><i>Methods:</i></b> Fifteen patients recruited for our prospective study on potentially hepatotoxic drugs were included. DILI diagnosis was based on RUCAM (Roussel Uclaf Causality Assessment Method) score and expert opinion and was supported by an in vitro test using monocyte-derived hepatocyte-like (MH) cells. <b><i>Results:</i></b> Median RUCAM score was 6 (range 4–8), indicating that DILI was possible or probable in all cases. The predominant types of liver injury were mixed (60%) and cholestatic (40%). While no elevation above 2 × ULN of ALP and TBIL was observed, gamma-glutamyltransferase (GGT) above 2 × ULN was identified in 8 of the patients. Six of the 15 patients did not achieve full remission and showed persistent elevation of GGT, which was significantly associated with peak GGT elevation above 2 × ULN (<i>p</i> = 0.005). <b><i>Conclusion:</i></b> Here we present a case series of patients with liver enzyme elevation below the conventional thresholds who developed DILI with a predominant GGT elevation leading to drug withdrawal and/or chronic elevation of liver parameters, in particular of GGT. Thus, we propose that DILI should be considered in particular in cases with marked increase of GGT even if conventional DILI threshold levels are not reached, resulting in discontinuation of the causative drug and/or close monitoring of the patients.

Monocyte-Derived Hepatocyte-Like Cell Test: A Novel Tool for in vitro Identification of Drug-Induced Liver Injury in Patients with Herbal or Dietary Supplements

BACKGROUND

Drug-induced liver injury caused by herbal and dietary supplements (HDS) has been an increasingly important phenomenon in recent years. Diagnosis is the major challenge. Definite causality assessment, especially in patients with concomitant prescription medicine or other potential causes of liver injury, can be impossible.

OBJECTIVES

We investigated the usefulness of an in vitro test on the basis of peripheral monocytes of the individual patients in patients with acute liver injury consuming HDS.

METHOD

Patients with acute liver injury who had been prospectively recruited by the University Hospital Munich (LMU, Munich) and the Chinese University of Hong Kong (CUHK) and who took at least 1 HDS were selected for this analysis. Diagnosis of drug-induced liver injury (DILI) was based on local expert adjudication, Roussel Uclaf Causality Assessment Method (RUCAM) score, and course of the disease and was supported by the monocyte-derived hepatocyte-like (MH) cell test.

RESULTS

We identified 47 patients with liver injury and intake of at least 1 HDS: 32 (68%) were diagnosed with DILI. HDS was determined as the causative agent in 28 out of those 32 patients. The MH cell test could correctly identify 29 out of those 32 DILI cases and showed false positive results in only 2 out of the 15 non-DILI patients. The MH cell test therefore reached a sensitivity and specificity of 90.6 and 86.7%, respectively, in patients with acute liver injury and HDS intake.

CONCLUSIONS

Our data provide evidence that the MH cell test can be a useful tool to identify the role of HDS in causing DILI and therefore support causality assessment in patients consuming HDS.

Is There an Increased Risk of Hepatotoxicity with Metamizole? A Comparative Cohort Study in Incident Users

INTRODUCTION

The analgesic metamizole, which has been withdrawn from the market in several countries due to the risk of agranulocytosis but is still available on the market in Germany and some other countries, has been associated with liver injury in published case reports; however, epidemiological studies on the risk of liver injury are limited.

OBJECTIVE

The aim of this study was to compare the risk of liver injury up to 270 days after the first start of treatment with metamizole with the corresponding risk in patients starting treatment with paracetamol, using a retrospective cohort incident user design.

METHODS

The first prescription for either metamizole or paracetamol in the Intercontinental Medical Statistics (IMS)^® Disease Analyzer Germany database during the study period (2009-2018) was identified in patients with at least 365 days of observation and no prior diagnosis of liver events, cancer or HIV, or treatment within the last 6 months with hepatotoxic drugs typically administered for chronic conditions. Each patient was followed for specific liver events for 90 days after the prescription. In case of a new prescription within 90 days, a new 90-day observation period started, up to a maximum of 270 days. Cox regression was used to compare the risk of liver injury in the two groups.

RESULTS

Metamizole was associated with a higher risk of liver injury compared with paracetamol (adjusted hazard ratio 1.69, 95% confidence interval 1.46-1.97). Sensitivity analyses were performed to evaluate the robustness of these findings. In all the sensitivity analyses, metamizole was still associated with a higher risk of liver injury, including an analysis where naproxen was used as a comparator instead of paracetamol.

CONCLUSIONS

Results from this study support previous studies suggesting that metamizole is associated with a significant risk of liver injury. Nevertheless, a possible impact of residual confounding cannot be excluded.

In-Vitro Approaches to Predict and Study T-Cell Mediated Hypersensitivity to Drugs

Mitigating the risk of drug hypersensitivity reactions is an important facet of a given pharmaceutical, with poor performance in this area of safety often leading to warnings, restrictions and withdrawals. In the last 50 years, efforts to diagnose, manage, and circumvent these obscure, iatrogenic diseases have resulted in the development of assays at all stages of a drugs lifespan. Indeed, this begins with intelligent lead compound selection/design to minimize the existence of deleterious chemical reactivity through exclusion of ominous structural moieties. Preclinical studies then investigate how compounds interact with biological systems, with emphasis placed on modeling immunological/toxicological liabilities. During clinical use, competent and accurate diagnoses are sought to effectively manage patients with such ailments, and pharmacovigilance datasets can be used for stratification of patient populations in order to optimise safety profiles. Herein, an overview of some of the in-vitro approaches to predict intrinsic immunogenicity of drugs and diagnose culprit drugs in allergic patients after exposure is detailed, with current perspectives and opportunities provided.

[Once upon a time the hepatotoxicity…]

The liver ensures a large part of xenobiotics metabolism thanks to its sizeable enzymatic equipment, its anatomical localization and its abundant vascularization. However, these various characteristics also make it a privileged target for toxic compounds, particularly in the case of a toxic metabolism. Xenobiotics-induced hepatotoxicity is a major cause of liver damage and a real challenge for clinicians, pharmaceutical industry, and health agencies. Intrinsic, i.e. predictable and reproducible hepatotoxicities occurring at threshold doses are distinguished from idiosyncratic hepatotoxicities, occurring in an unpredictable manner in people with individual susceptibilities. Among them, idiosyncratic immune-mediated hepatotoxicity pathophysiology is still unclear. However, the development of tools to improve the prediction and understanding of these disorders may open avenues to the identification of risk factors and new mechanisms of toxicity.

Oxidative Stress in Drug-Induced Liver Injury (DILI): From Mechanisms to Biomarkers for Use in Clinical Practice

Idiosyncratic drug-induced liver injury (DILI) is a type of hepatic injury caused by an uncommon drug adverse reaction that can develop to conditions spanning from asymptomatic liver laboratory abnormalities to acute liver failure (ALF) and death. The cellular and molecular mechanisms involved in DILI are poorly understood. Hepatocyte damage can be caused by the metabolic activation of chemically active intermediate metabolites that covalently bind to macromolecules (e.g., proteins, DNA), forming protein adducts-neoantigens-that lead to the generation of oxidative stress, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress, which can eventually lead to cell death. In parallel, damage-associated molecular patterns (DAMPs) stimulate the immune response, whereby inflammasomes play a pivotal role, and neoantigen presentation on specific human leukocyte antigen (HLA) molecules trigger the adaptive immune response. A wide array of antioxidant mechanisms exists to counterbalance the effect of oxidants, including glutathione (GSH), superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX), which are pivotal in detoxification. These get compromised during DILI, triggering an imbalance between oxidants and antioxidants defense systems, generating oxidative stress. As a result of exacerbated oxidative stress, several danger signals, including mitochondrial damage, cell death, and inflammatory markers, and microRNAs (miRNAs) related to extracellular vesicles (EVs) have already been reported as mechanistic biomarkers. Here, the status quo and the future directions in DILI are thoroughly discussed, with a special focus on the role of oxidative stress and the development of new biomarkers.

Liver Injury Associated with Metamizole Exposure: Features of an Underestimated Adverse Event

INTRODUCTION AND OBJECTIVE

The potential of metamizole to cause drug-induced liver injury (DILI) has received increasing attention. We investigated the distinguishing features of a case series comprising 32 patients with suspected metamizole-induced DILI.

METHODS

For the current analysis, 32 of 238 patients with DILI included in our prospective study on drugs potentially causing DILI were included. Diagnosis of DILI was based on expert opinion and RUCAM (Roussel Uclaf Causality Assessment Method) score and supported by an in vitro test using monocyte-derived hepatocyte-like cells.

RESULTS

Suspected metamizole-DILI was characterised by a female predominance, hepatocellular pattern of injury, high proportion of antinuclear antibody positivity, and predominance of eosinophilic cell infiltration and necrosis in the histopathological analysis. With 22%, a high proportion of these metamizole-associated liver injury cases developed acute liver failure, which was characterised by a longer latency of metamizole use and more pronounced liver biochemistry abnormalities at onset and peak levels. Furthermore, jaundice was a common finding in the metamizole-associated liver injury cases with 66% presenting with peak bilirubin levels of 3 mg/dL or higher, which was associated with a worse outcome and a higher frequency of acute liver failure.

CONCLUSIONS

Our analysis of a well-characterised DILI cohort further supports the potential of metamizole causing DILI and provides important features for the establishment of a signature pattern of liver injury observed in patients treated with metamizole.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: NCT02353455.

Antimitochondrial Rather than Antinuclear Antibodies Correlate with Severe Drug-Induced Liver Injury

INTRODUCTION

A proportion of patients with drug-induced liver injury (DILI) present with autoantibodies, which has led to the current concept of autoimmune-like DILI. However, no standardized definition exists and the clinical relevance has not been studied in detail yet.

METHODS

143 patients with DILI enrolled in a prospective study were analyzed. DILI diagnosis was based on the monocyte-derived hepatocyte-like cell test and supported by Roussel Uclaf Causality Assessment Method (RUCAM) and expert adjudication. Testing for antinuclear antibodies (ANA) and antimitochondrial antibodies (AMA) was performed using immunofluorescence. ANA titers ≥1:100 were considered positive and ≥1:400 clinically relevant; AMA positivity was considered at titers ≥1:100.

RESULTS

67% exhibited ANA ≥1:100 and 29% ANA ≥1:400; 10% were AMA positive. There was no significant correlation between the ANA titers and the causative drug, while AMA positive patients had taken nonsteroidal anti-inflammatory drugs more frequently. No difference was seen regarding clinical characteristics or laboratory parameters in patients with ANA ≥1:400, while patients with positive AMA presented with higher aminotransferases, bilirubin, and international normalized ratio. Significantly higher proportions of patients with ANA ≥1:400 or AMA positivity exhibited elevated immunoglobulin G levels. AMA positivity but not elevated ANA titers correlated with a higher proportion of Hy's law positivity.

CONCLUSION

A closer look in a causality proven DILI cohort provided no evidence that presence of ANA titers is specific for DILI by a certain medication. AMA rather than ANA positivity was related to a more pronounced liver injury.

Drug-Induced Liver Injury After Liver Transplantation

Drug-induced liver injury (DILI) is an adverse reaction to many drugs in common use that in a liver transplantation (LT) recipient may cause graft dysfunction and may even lead to graft loss and the need for retransplantation. However, several potential clinical scenarios, such as graft rejection and infection, can confound the diagnosis of suspected DILI in the setting of LT. This makes causal assessment of a new liver injury more uncertain and has traditionally precluded collection of bona fide cases of DILI affecting LT patients in prospective DILI registries and cohorts. Although no studies have yet determined a greater susceptibility of the transplant patient to DILI, these patients nevertheless present certain risk factors that can theoretically increase the risk of DILI. These include the fact that these patients are polymedicated, use drugs that are potentially hepatotoxic, and can have coexisting hepatitis B or C viruses in addition to other factors found in nontransplant patients, such as genetic variants. Therefore, awareness is crucial of any potential hepatotoxic effect of drugs used in the LT recipient and their possible implication in any case of liver dysfunction. In the present article, we review the most common drugs used in LT recipients from a liver safety perspective and address the main pitfalls in attributing causality in this clinical setting. We also affirm the need for further research and collaboration in this somewhat neglected topic in the field of DILI.

Understanding Idiosyncratic Toxicity: Lessons Learned from Drug-Induced Liver Injury

Idiosyncratic adverse drug reactions (IADRs) encompass a diverse group of toxicities that can vary by drug and patient. The complex and unpredictable nature of IADRs combined with the fact that they are rare makes them particularly difficult to predict, diagnose, and treat. Common clinical characteristics, the identification of human leukocyte antigen risk alleles, and drug-induced proliferation of lymphocytes isolated from patients support a role for the adaptive immune system in the pathogenesis of IADRs. Significant evidence also suggests a requirement for direct, drug-induced stress, neoantigen formation, and stimulation of an innate response, which can be influenced by properties intrinsic to both the drug and the patient. This Perspective will provide an overview of the clinical profile, mechanisms, and risk factors underlying IADRs as well as new approaches to study these reactions, focusing on idiosyncratic drug-induced liver injury.

Drug-Induced Liver Injury: Highlights of the Recent Literature

Drug-induced liver injury (DILI), herbal-induced liver injury, and herbal and dietary supplement (HDS)-induced liver injury are an important aspect of drug safety. Knowledge regarding responsible drugs, mechanisms, risk factors, and the diagnostic tools to detect liver injury have continued to grow in the past year. This review highlights what we considered the most significant publications from among more than 1800 articles relating to liver injury from medications, herbal products, and dietary supplements in 2017 and 2018. The US Drug-Induced Liver Injury Network (DILIN) prospective study highlighted several areas of ongoing study, including the potential utility of human leukocyte antigens and microRNAs as DILI risk factors and new data on racial differences, the role of alcohol consumption, factors associated with prognosis, and updates on the clinical signatures of autoimmune DILI, thiopurines, and HDS agents. Novel data were also generated from the Spanish and Latin American DILI registries as well as from Chinese and Korean case series. A few new agents causing DILI were added to the growing list in the past 2 years, including sodium-glucose co-transporter-2 inhibitors, as were new aspects of chemotherapy-associated liver injury. A number of cases reported previously described hepatotoxins confirmed via the Roussel Uclaf Causality Assessment Method (RUCAM; e.g., norethisterone, methylprednisolone, glatiramer acetate) and/or the DILIN method (e.g., celecoxib, dimethyl fumarate). Additionally, much work centered on elucidating the pathophysiology of DILI, including the importance of bile salt export pumps and immune-mediated mechanisms. Finally, it must be noted that, while hundreds of new studies described DILI in 2017-2018, the quality of such reports must always be addressed. Björnsson reminds us to remain very critical of the data when addressing the future utility of a study, which is why it is so important to adhere to a standardized method such as RUCAM when determining DILI causality. While drug-induced hepatotoxicity remains a diagnosis of exclusion, the diverse array of publications that appeared in 2017 and 2018 provided important advances in our understanding of DILI, paving the way for our improved ability to make a more definitive diagnosis and risk assessment.

Acute and sub-acute toxicity of Echinops kebericho decoction in rats

BACKGROUND

Echinops kebericho is widely used for treatment of a variety of diseases including infectious, non-infectious disease and fumigation during child birth. Antibacterial, antimalarial, anti-leshimania, anti-diarrheal and insect repellent activities have been elucidated. Its toxicity profile is not yet investigated and thus this study was to investigate acute and sub-acute toxicity of E. kebericho decoctions.

METHODS

Acute toxicity study was performed in female Wistar albino rats with single oral dose and followed up to 14 days. The sub-acute oral dose toxicity studies were conducted in rats of both sexes in accordance with the repeated dose 28-day oral toxicity study in rodent OECD guidelines. Physical observations were made regularly during the study period while body weight was measured weekly. Organ weight, histopathology, clinical chemistry and hematology data were collected on the 29th day. Results were presented as mean ± standard deviation. One-way analysis of variance (ANOVA) was performed if assumptions were met; otherwise Kruskal-Wallis analysis was performed.

RESULT

Oral administration of E. kebericho decoction showed no treatment-related mortality in female rats up to the dose of 5000 mg/kg. In sub-acute toxicity studies, no significant treatment-related abnormalities were observed compared to negative controls. Food consumption, body weight, organ weight, hematology, clinical chemistry, and histopathology did not show significant variation between controls and treatment groups. However, creatinine, relative lung weight, triglycerides, and monocytes were lower in treated compared to control groups. Significant variations between male and female groups in food consumption, relative organ weight, hematology, clinical chemistry were observed. Histolo-pathology of high-dose treated groups showed fatty liver.

CONCLUSION

Echinops kebericho showed LD₅₀ of greater than 5000 mg/kg in acute toxicity study and is well tolerated up to the dose of 600 mg/kg body weight in sub-acute toxicity study.

Drug-Induced Liver Injury: Biomarkers, Requirements, Candidates, and Validation

The hepatotoxicity of drugs is the main cause of drug withdrawal from the pharmaceutical market and interruption of the development of new molecules. Biomarkers are useful in several situations. In case of suspected drug-induced liver injury (DILI), biomarkers can be used to confirm liver damage, its severity, prognosis, confirm drug causality, or define the type of DILI. In this review, we will first present the currently used biomarkers and candidate biomarkers for the future. The current biomarkers are certainly very helpful including with the assistance of diagnostic method such the Roussel Uclaf Causality Assessment Method, but provide a limited information for the early detection of liver injury, the role of specific drug and the prediction of DILI. Some biomarkers are promising but they are not yet available for routine use. Studies are still needed to confirm their interest, particularly in comparison to Roussel Uclaf Causality Assessment Method.

T-Cell Activation by Low Molecular Weight Drugs and Factors That Influence Susceptibility to Drug Hypersensitivity

Drug hypersensitivity reactions adversely affect treatment outcome, increase the length of patients' hospitalization, and limit the prescription options available to physicians. In addition, late stage drug attrition and the withdrawal of licensed drugs cost the pharmaceutical industry billions of dollars. This significantly increases the overall cost of drug development and by extension the price of licensed drugs. Drug hypersensitivity reactions are characterized by a delayed onset, and reactions tend to be more serious upon re-exposure. The role of drug-specific T-cells in the pathogenesis of drug hypersensitivity reactions and definition of the nature of the binding interaction of drugs with HLA and T-cell receptors continues to be the focus of intensive research, primarily because susceptibility is associated with expression of one or a small number of HLA alleles. This review critically examines the mechanisms of T-cell activation by drugs. Specific examples of drugs that activate T-cells via the hapten, the pharmacological interaction with immune receptors and the altered self-peptide repertoire pathways, are discussed. Furthermore, the impacts of drug metabolism, drug-protein adduct formation, and immune regulation on the development of drug antigen-responsive T-cells are highlighted. The knowledge gained from understanding the pathways of T-cell activation and susceptibility factors for drug hypersensitivity will provide the building blocks for the development of predictive in vitro assays that will prevent or help to minimize the incidence of these reactions in clinic.

Strategies for Early Prediction and Timely Recognition of Drug-Induced Liver Injury: The Case of Cyclin-Dependent Kinase 4/6 Inhibitors

The idiosyncratic nature of drug-induced liver injury (DILI) represents a current challenge for drug developers, regulators and clinicians. The myriad of agents (including medications, herbals, and dietary supplements) with recognized DILI potential not only strengthens the importance of the post-marketing phase, when urgent withdrawal sometimes occurs for rare unanticipated liver toxicity, but also shows the imperfect predictivity of pre-clinical models and the lack of validated biomarkers beyond traditional, non-specific liver function tests. After briefly reviewing proposed key mechanisms of DILI, we will focus on drug-related risk factors (physiochemical and pharmacokinetic properties) recently proposed as predictors of DILI and use cyclin-dependent kinase 4/6 inhibitors, relatively novel oral anticancer medications approved for breast cancer, as a case study to discuss the feasibility of early detection of DILI signals during drug development: published data from pivotal clinical trials, unpublished post-marketing reports of liver adverse events, and pharmacokinetic properties will be used to provide a comparative evaluation of their liver safety and gain insight into drug-related risk factors likely to explain the observed differences.

Risk profiling using metabolomic characteristics for susceptible individuals of drug-induced liver injury caused by Polygonum multiflorum

Idiosyncratic drug-induced liver injury (IDILI) is a rare but potentially severe adverse drug reaction. To date, identifying individuals at risk for IDILI remains challenging. This is a prospective study, where a nested case-control (1:5) design was adopted. For six patients who had abnormalities in liver function test after Polygonum multiflorum Thunb. (PM) ingestion (susceptible group), 30 patients with normal liver function were matched (tolerant group). Based on liquid chromatography-mass spectrometry, metabolomics analysis was done on serum samples prior to PM ingestion, to screen the differential metabolites and characterize metabolomic profiles of patient serum in the two groups. Multivariate analysis showed that there were remarkable separations between susceptible and tolerant groups. A total of 25 major differential metabolites were screened out, involving glycerophospholipid metabolism, sphingolipid metabolism, fatty acid metabolism, histidine metabolism and aromatic amino acid metabolism. Wherein, the area under the curve of the receiver operating characteristic curves of metabolites PE 22:6, crotonoyl-CoA, 2E-tetradecenoyl-CoA, phenyllactic acid, indole-5,6-quinone, phosphoribosyl-ATP were all greater than 0.9. The overall serum metabolic profile comprising of 25 metabolites could clearly distinguish susceptible and tolerant groups. This proof-of-concept study used metabolomics to characterize the metabolic profile of IDILI risk individuals before drug ingestion for the first time. The metabolome characteristics in patient serum before PM ingestion may predict the risk of liver injury after PM ingestion.

Early ALT response to corticosteroid treatment distinguishes idiosyncratic drug-induced liver injury from autoimmune hepatitis

BACKGROUND

Drug-induced liver injury (DILI) and idiopathic autoimmune hepatitis (AIH) are competing diagnoses in patients with acute liver injury (ALI) and drug intake. In absence of unequivocal markers, scores like RUCAM and AIH are used to distinguish both entities. However, in some cases the diagnosis remains ambiguous. Our aim was to identify a simple parameter to discriminate DILI and AIH shortly after starting corticosteroid treatment.

METHODS

For the current analysis, 44 patients with ALI who took at least one drug and who received corticosteroids were included and comprised 22 DILI and 22 AIH cases. Scores of AIH and RUCAM were calculated at initial presentation, the final diagnosis was made from analysing the course of disease. Changes in the serum alanine aminotransferase (ALT) concentrations after starting corticosteroid treatment were determined and compared between the DILI and AIH groups.

RESULTS

Fifty-nine per cent of patients (n = 26) were correctly classified at presentation by AIH score and RUCAM respectively. However, in one-third (n = 13) of the 44 patients, results were inconclusive and five other patients were misclassified. The decrease in ALT levels 1 week after the initiation of steroid therapy was significantly more pronounced in patients with the final diagnosis of DILI than in AIH patients (accuracy 77%). This difference was also observed in the 18 initially misclassified or inconclusive cases (accuracy 83%).

CONCLUSION

Short-term response of ALT to corticosteroid therapy helps to differentiate DILI and AIH. This finding may be helpful in treatment decision for patients with inconclusive diagnostic scores.

Drug-induced liver injury

Drug-induced liver injury (DILI) is an adverse reaction to drugs or other xenobiotics that occurs either as a predictable event when an individual is exposed to toxic doses of some compounds or as an unpredictable event with many drugs in common use. Drugs can be harmful to the liver in susceptible individuals owing to genetic and environmental risk factors. These risk factors modify hepatic metabolism and excretion of the DILI-causative agent leading to cellular stress, cell death, activation of an adaptive immune response and a failure to adapt, with progression to overt liver injury. Idiosyncratic DILI is a relative rare hepatic disorder but can be severe and, in some cases, fatal, presenting with a variety of phenotypes, which mimic other hepatic diseases. The diagnosis of DILI relies on the exclusion of other aetiologies of liver disease as specific biomarkers are still lacking. Clinical scales such as CIOMS/RUCAM can support the diagnostic process but need refinement. A number of clinical variables, validated in prospective cohorts, can be used to predict a more severe DILI outcome. Although no pharmacological therapy has been adequately tested in randomized clinical trials, corticosteroids can be useful, particularly in the emergent form of DILI related to immune-checkpoint inhibitors in patients with cancer.

Drug-Drug Combinations Can Enhance Toxicity as Shown by Monocyte-Derived Hepatocyte-like Cells From Patients With Idiosyncratic Drug-Induced Liver Injury

Study identifier

ClinicalTrials.gov NCT 02353455.

Tools for causality assessment in drug-induced liver disease

PURPOSE OF REVIEW

There are three liver-specific causality assessment tools currently available to guide clinical diagnosis of Drug-Induced Liver Injury (DILI): Roussel-Uclaf Causality Assessment Method (RUCAM), Digestive-Disease-Week Japan 2004 scale (DDW-J), and Clinical Diagnostic Scale (CDS). The purpose of this review is to assess these tools and discuss how to improve the causality assessment process as a whole.

RECENT FINDINGS

Existing DILI-specific causality assessment tools are surprisingly similar and exhibit only minor differences in point allocation. But difference in threshold for likelihood of being DILI. We reviewed the literature on currently used causality assessment tools, identified areas for future improvement, and herein propose approaches for refinement. Opportunities to improve current models, as well as the assessment process, in general, include in particular provision of more precise clinical detail and to perhaps add new components to scoring systems. For example, the incorporation of drug-specific clinical signature patterns, accounting for a drug's inherent hepatotoxicity potential, and/or incorporation of other drug properties to scoring systems may allow enhancement. Further, more systemic exclusion of competing diagnoses is needed. Finally, causality assessment processes will likely benefit from a data-driven and computer-assisted approach.

SUMMARY

Current tools used for DILI adjudication are imperfect. Avenues to improve these tools are described.

Novel Approaches to Causality Adjudication in Drug-Induced Liver Disease

Purpose of Review

Drug induced liver injury (DILI) is a complex diagnosis dominantly based of exclusion.

Recent Findings

Currently available causality assessment instruments are considered to be suboptimal. Expert opinion appears to be best method to adjudicate causality, but is impractical to implement on a wide scale basis. Thus, new approaches are needed, for example improving the specificity of current scoring systems. A further option would be to develop a system that utilizes computer-based scoring - which would reduce human error. Additionally, it would be ideal to have available drug specific scoring systems, based on drugs' characteristic "phenotypes" (presentation and pattern of injury). Eventually, a validated system could be integrated within the electronic health information system.

Summary

This review highlights an avenue to an improved Causality Assessment Tool.

Proteomics Analysis of Monocyte-Derived Hepatocyte-Like Cells Identifies Integrin Beta 3 as a Specific Biomarker for Drug-Induced Liver Injury by Diclofenac

Idiosyncratic drug-induced liver injury (iDILI) is a major cause of acute liver failure resulting in liver transplantation or death. Prediction and diagnosis of iDILI remain a great challenge, as current models provide unsatisfying results in terms of sensitivity, specificity, and prognostic value. The absence of appropriate tools for iDILI detection also impairs the development of reliable biomarkers. Here, we report on a new method for identification of drug-specific biomarkers. We combined the advantages of monocyte-derived hepatocyte-like (MH) cells, able to mimic individual characteristics, with those of a novel mass spectrometry-based proteomics technology to assess potential biomarkers for Diclofenac-induced DILI. We found over 2,700 proteins differentially regulated in MH cells derived from individual patients. Herefrom, we identified integrin beta 3 (ITGB3) to be specifically upregulated in Diclofenac-treated MH cells from Diclofenac-DILI patients compared to control groups. Finally, we validated ITGB3 by flow cytometry analysis of whole blood and histological staining of liver biopsies derived from patients diagnosed with Diclofenac-DILI. In summary, our results show that biomarker candidates can be identified by proteomics analysis of MH cells. Application of this method to a broader range of drugs in the future will exploit its full potential for the development of drug-specific biomarkers. Data are available via ProteomeXchange with identifier PXD008918.