Relationship between daily dose of oral medications and idiosyncratic drug-induced liver injury: search for signals

Role of Gut Microecology in the Pathogenesis of Drug-Induced Liver Injury and Emerging Therapeutic Strategies

Drug-induced liver injury (DILI) is a common clinical pharmacogenic disease. In the United States and Europe, DILI is the most common cause of acute liver failure. Drugs can cause hepatic damage either directly through inherent hepatotoxic properties or indirectly by inducing oxidative stress, immune responses, and inflammatory processes. These pathways can culminate in hepatocyte necrosis. The role of the gut microecology in human health and diseases is well recognized. Recent studies have revealed that the imbalance in the gut microecology is closely related to the occurrence and development of DILI. The gut microecology plays an important role in liver injury caused by different drugs. Recent research has revealed significant changes in the composition, relative abundance, and distribution of gut microbiota in both patients and animal models with DILI. Imbalance in the gut microecology causes intestinal barrier destruction and microorganism translocation; the alteration in microbial metabolites may initiate or aggravate DILI, and regulation and control of intestinal microbiota can effectively mitigate drug-induced liver injury. In this paper, we provide an overview on the present knowledge of the mechanisms by which DILI occurs, the common drugs that cause DILI, the gut microbiota and gut barrier composition, and the effects of the gut microbiota and gut barrier on DILI, emphasizing the contribution of the gut microecology to DILI.

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.

Chinese guideline for the diagnosis and treatment of drug-induced liver injury: an update

Drug-induced liver injury (DILI) is an important adverse drug reaction that can lead to acute liver failure or even death in severe cases. Currently, the diagnosis of DILI still follows the strategy of exclusion. Therefore, a detailed history taking and a thorough and careful exclusion of other potential causes of liver injury is the key to correct diagnosis. This guideline was developed based on evidence-based medicine provided by the latest research advances and aims to provide professional guidance to clinicians on how to identify suspected DILI timely and standardize the diagnosis and management in clinical practice. Based on the clinical settings in China, the guideline also specifically focused on DILI in chronic liver disease, drug-induced viral hepatitis reactivation, common causing agents of DILI (herbal and dietary supplements, anti-tuberculosis drugs, and antineoplastic drugs), and signal of DILI in clinical trials and its assessment.

Higher risk of hepatotoxicity associated with cabozantinib in cancer patients

BACKGROUND

The efficacy of cabozantinib has attracted interest in various solid tumors. The primary aim of this study was to evaluate the risk of hepatotoxicity associated with cabozantinib in the patients with cancer.

METHODS

PubMed, Cochrane, and EMBASE databases were searched for published randomized controlled trials (RCTs) from inception to September 9, 2023. The mainly outcomes were all-grade and grade ≥3 elevation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), expressed as relative risk (RR) and 95% confidence interval (CI). All data were pooled using fixed-effect or random-effects models according to the heterogeneity of the included RCTs.

RESULTS

Among the 922 records identified, 8 RCTs incorporating 2613 patients with cancer were included. For patients receiving cabozantinib, the relative risks of all-grade AST elevation (RR, 2.63; 95% CI, 2.16-3.20, P < 0.001), all-grade ALT elevation (RR, 2.89; 95% CI, 2.31-3.60, P < 0.001), grade ≥3 AST elevation (RR, 2.26; 95% CI, 1.34-3.83, P = 0.002), and grade ≥3 ALT elevation (RR, 3.40; 95% CI, 1.65-7.01, P < 0.001) were higher than those of patients who did not receive cabozantinib group. Further subgroup analysis showed that the relative risk of hepatotoxicity associated with cabozantinib was higher than that in the other TKIs (erlotinib, sunitinib, and sorafenib) and the non-TKI drug groups (everolimus, prednisone, mitoxantrone, and paclitaxel).

CONCLUSIONS

Compared with other solid tumor drugs, such as everolimus, sorafenib, sunitinib, paclitaxel, mitoxantrone-prednisone et al., cabozantinib has a higher risk of hepatotoxicity.

Venetoclax dose adjustment due to drug-drug interactions: a case report and literature review

The primary aim of the study is to discuss the potential interactions between venetoclax and common drugs used in department of hematology and the corresponding effects on the efficacy and safety of venetoclax treatment. Here, we report an acute myeloid leukemia patient treated with venetoclax and posaconazole, and the dose of venetoclax was adjusted due to drug interactions. Clinical pharmacists actively participated in treatment of this patient to provide pharmacy care to assist clinicians to identify the venetoclax-induced liver function impairment and give timely management. The case reported here is hoped to provide reference for clinical venetoclax treatment in patients with such disease. Clinical pharmacists should actively participate in clinical treatment, actively screen potential drug interactions, strengthen cooperation and communication with doctors, provide patients with high-quality pharmaceutical services, and establish clinical pharmacists' status in the multidisciplinary treatment of tumor.

Drug Discovery Efforts to Identify Novel Treatments for Neglected Tropical Diseases - Cysteine Protease Inhibitors

BACKGROUND

Neglected tropical diseases are a severe burden for mankind, affecting an increasing number of people around the globe. Many of those diseases are caused by protozoan parasites in which cysteine proteases play a key role in the parasite's pathogenesis.

OBJECTIVE

In this review article, we summarize the drug discovery efforts of the research community from 2017 - 2022 with a special focus on the optimization of small molecule cysteine protease inhibitors in terms of selectivity profiles or drug-like properties as well as in vivo studies. The cysteine proteases evaluated by this methodology include Cathepsin B1 from Schistosoma mansoni, papain, cruzain, falcipain, and rhodesain.

METHODS

Exhaustive literature searches were performed using the keywords "Cysteine Proteases" and "Neglected Tropical Diseases" including the years 2017 - 2022. Overall, approximately 3'000 scientific papers were retrieved, which were filtered using specific keywords enabling the focus on drug discovery efforts.

RESULTS AND CONCLUSION

Potent and selective cysteine protease inhibitors to treat neglected tropical diseases were identified, which progressed to pharmacokinetic and in vivo efficacy studies. As far as the authors are aware of, none of those inhibitors reached the stage of active clinical development. Either the inhibitor's potency or pharmacokinetic properties or safety profile or a combination thereof prevented further development of the compounds. More efforts with particular emphasis on optimizing pharmacokinetic and safety properties are needed, potentially by collaborations of academic and industrial research groups with complementary expertise. Furthermore, new warheads reacting with the catalytic cysteine should be exploited to advance the research field in order to make a meaningful impact on society.

NAD+ Precursors in Human Health and Disease: Current Status and Future Prospects

Significance: Nicotinamide adenine dinucleotide (NAD+) acts as a cofactor in many important biological processes. The administration of NAD+ precursors increases the intracellular NAD+ pool and has beneficial effects on physiological changes and diseases associated with aging in various organisms, including rodents and humans. Recent Advances: Evidence from preclinical studies demonstrating the beneficial effects of NAD+ precursors has rapidly increased in the last decade. The results of these studies have prompted the development of clinical trials using NAD+ precursors, particularly nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). In addition, in vivo studies of NAD+ metabolism have rapidly progressed. Critical Issues: Several studies have demonstrated that the oral administration of NAD+ precursors, such as NR and NMN, is safe and significantly increases NAD+ levels in humans. However, the efficacy of these NAD+ precursors is lower than expected from the results of preclinical studies. In addition, the identification of the contribution of the host-gut microbiota interactions to NR and NMN metabolism has added to the complexity of NAD+ metabolism. Future Directions: Further studies are required to determine the efficacy of NAD+ precursors in humans. Further in vivo studies of NAD+ metabolism are required to optimize the effects of NAD+ supplementation. There is also a need for methods of delivering NAD+ precursors to target organs or tissues to increase the outcomes of clinical trials. Antioxid. Redox Signal. 39, 1133-1149.

Microphysiological Models for Mechanistic-Based Prediction of Idiosyncratic DILI

Drug-induced liver injury (DILI) is a major contributor to high attrition rates among candidate and market drugs and a key regulatory, industry, and global health concern. While acute and dose-dependent DILI, namely, intrinsic DILI, is predictable and often reproducible in preclinical models, the nature of idiosyncratic DILI (iDILI) limits its mechanistic understanding due to the complex disease pathogenesis, and recapitulation using in vitro and in vivo models is extremely challenging. However, hepatic inflammation is a key feature of iDILI primarily orchestrated by the innate and adaptive immune system. This review summarizes the in vitro co-culture models that exploit the role of the immune system to investigate iDILI. Particularly, this review focuses on advancements in human-based 3D multicellular models attempting to supplement in vivo models that often lack predictability and display interspecies variations. Exploiting the immune-mediated mechanisms of iDILI, the inclusion of non-parenchymal cells in these hepatoxicity models, namely, Kupffer cells, stellate cells, dendritic cells, and liver sinusoidal endothelial cells, introduces heterotypic cell-cell interactions and mimics the hepatic microenvironment. Additionally, drugs recalled from the market in the US between 1996-2010 that were studies in these various models highlight the necessity for further harmonization and comparison of model characteristics. Challenges regarding disease-related endpoints, mimicking 3D architecture with different cell-cell contact, cell source, and the underlying multi-cellular and multi-stage mechanisms are described. It is our belief that progressing our understanding of the underlying pathogenesis of iDILI will provide mechanistic clues and a method for drug safety screening to better predict liver injury in clinical trials and post-marketing.

The effect of evolocumab alone and in combination with atorvastatin on atherosclerosis progression and TLRs expression

Evolocumab, a PCSK-9 inhibitor, is known for its ability to reduce low-density lipoprotein cholesterol (LDL-C). This study aimed to investigate the effects of evolocumab, alone or in combination with atorvastatin, on the progression of atherosclerosis. Fifty male domestic rabbits were randomly assigned to five groups: control, high cholesterol diet, evolocumab vehicle (dimethyl sulfoxide, DMSO), evolocumab alone, and evolocumab plus atorvastatin. Serum levels of interleukin 10 (IL-10), IL-17, IL-1β, intracellular adhesion molecule (ICAM), and vascular adhesion molecule (VCAM) were measured. Toll-like receptor (TLR) expression on monocytes was evaluated using flow cytometry. Histopathological examination and measurement of intimal thickness (IT) were also conducted. The results revealed that the evolocumab produced a statistically significant (p<0.05) reduction in lipid profile at 5 weeks, with the peak effect occurring at 10 weeks. Furthermore, the inhibitor reduced TLRs at 10 weeks to 10.83±1.8 and intimal thickness to 160.66±9.45. IL-17, IL-1β, ICAM, and VCAM were significantly reduced by evolocumab treatment, with the improvement of the histopathological changes in the aortic wall. The combination of evolocumab and atorvastatin caused a more statistically significant reduction in TLRs at 10 weeks to 5.08±1.2 and intimal thickness to 121.79±5.3. IL-17, IL-1β, ICAM, and VCAM were significantly (p<0.05) reduced by the combination, and the histopathological changes in the aortic wall were significantly improved. In conclusion, evolocumab delays the progression of atherosclerosis by modulating inflammatory pathways.

Hepatoxicity induced by clozapine: Case report and brief review

INTRODUCTION

Antipsychotics are drugs that can produce transient elevations of hepatic enzymes. Clozapine is an atypical antipsychotic used in treatment-resistant schizophrenia and there is evidence that it can produce elevations of hepatic transaminases, expression of liver damage in a hepatocellular pattern.

METHODS

Case report and non-systematic review of the relevant literature.

CASE PRESENTATION

A 39-year-old woman with a diagnosis of paranoid schizophrenia attended the emergency department of a general hospital for nausea, vomiting and jaundice that appeared after the initiation of clozapine. There was no clinical improvement during hospitalisation, and death occurred after 44 days.

LITERATURE REVIEW

Clozapine can increase the liver enzyme levels transiently and asymptomatically; however, there are clinical criteria that recommend the withdrawal of the antipsychotic.

CONCLUSIONS

This is the third case reported in the literature of a fatal outcome of clozapine-induced hepatotoxicity.

An Immunological Perspective on the Mechanism of Drug Induced Liver Injury: Focused on Drugs for Treatment of Hepatocellular Carcinoma and Liver Transplantation

The liver is frequently exposed to potentially toxic materials, and it is the primary site of clearance of foreign agents, along with many innate and adaptive immune cells. Subsequently, drug induced liver injury (DILI), which is caused by medications, herbs, and dietary supplements, often occurs and has become an important issue in liver diseases. Reactive metabolites or drug-protein complexes induce DILI via the activation of various innate and adaptive immune cells. There has been a revolutionary development of treatment drugs for hepatocellular carcinoma (HCC) and liver transplantation (LT), including immune checkpoint inhibitors (ICIs), that show high efficacy in patients with advanced HCC. Along with the high efficacy of novel drugs, DILI has become a pivotal issue in the use of new drugs, including ICIs. This review demonstrates the immunological mechanism of DILI, including the innate and adaptive immune systems. Moreover, it aims to provide drug treatment targets, describe the mechanisms of DILI, and detail the management of DILI caused by drugs for HCC and LT.

LSD1 inhibitors for cancer treatment: Focus on multi-target agents and compounds in clinical trials

Histone lysine-specific demethylase 1 (LSD1/KDM1A) was first identified in 2004 as an epigenetic enzyme able to demethylate specific lysine residues of histone H3, namely H3K4me1/2 and H3K9me1/2, using FAD as the cofactor. It is ubiquitously overexpressed in many types of cancers (breast, gastric, prostate, hepatocellular, and esophageal cancer, acute myeloid leukemia, and others) leading to block of differentiation and increase of proliferation, migration and invasiveness at cellular level. LSD1 inhibitors can be grouped in covalent and non-covalent agents. Each group includes some hybrid compounds, able to inhibit LSD1 in addition to other target(s) at the same time (dual or multitargeting compounds). To date, 9 LSD1 inhibitors have entered clinical trials, for hematological and/or solid cancers. Seven of them (tranylcypromine, iadademstat (ORY-1001), bomedemstat (IMG-7289), GSK-2879552, INCB059872, JBI-802, and Phenelzine) covalently bind the FAD cofactor, and two are non-covalent LSD1 inhibitors [pulrodemstat (CC-90011) and seclidemstat (SP-2577)]. Another TCP-based LSD1/MAO-B dual inhibitor, vafidemstat (ORY-2001), is in clinical trial for Alzheimer's diseases and personality disorders. The present review summarizes the structure and functions of LSD1, its pathological implications in cancer and non-cancer diseases, and the identification of LSD1 covalent and non-covalent inhibitors with different chemical scaffolds, including those involved in clinical trials, highlighting their potential as potent and selective anticancer agents.

Estimating drug-induced liver injury risk by in vitro molecular initiation response and pharmacokinetic parameters for during early drug development

Drug-induced liver injury (DILI) is a major factor influencing new drug withdrawal; therefore, an appropriate toxicity assessment at the preclinical stage is required. Previous in silico models have been established using compound information listed in large data sources, thereby limiting the DILI risk prediction for new drugs. Herein, we first constructed a model to predict DILI risk based on a molecular initiating event (MIE) predicted by quantitative structure-activity relationships, admetSAR parameters (e.g. cytochrome P450 reactivity, plasma protein binding, and water-solubility), and clinical information (maximum daily dose [MDD] and reactive metabolite [RM]) for 186 compounds. The accuracy of the models using MIE, MDD, RM, and admetSAR alone were 43.2%, 47.3%, 77.0%, and 68.9%, while the "predicted MIE + admetSAR + MDD + RM" model's accuracy was 75.7%. The contribution of MIE to the overall prediction accuracy was little effect or rather worsening it. However, it was considered that MIE was a valuable parameter and that it contributed to detect high DILI risk compounds in the early development stage. We next examined the effect of stepwise changes in MDD on altering the DILI risk and estimating the maximum safety dose (MSD) for clinical use based on structural information, admetSAR, and MIE parameters because it is important to estimate the dose that could prevent the DILI onset in clinical conditions. Low-MSD compounds might increase the DILI risk, as these compounds were classified as "most-DILI concern" at low doses. In conclusion, MIE parameters were especially useful to check the DILI concern compounds and to prevent the underestimation of DILI risk in the early stage of drug development.

Review article: clinical assessment of suspected drug-induced liver injury and its management

BACKGROUND

Idisyncratic drug-induced liver injury (DILI) is a rare instance of liver injury after exposure to an otherwise safe drug or herbal or dietary supplement. DILI can be associated with significant morbidity and mortality. Furthermore, it is an important consideration in drug development due to safety concerns.

AIMS AND METHODS

To highlight pearls and pitfalls to aid clinicians in diagnosing DILI and surmising the management options. We also share the best practices from personal insights developed from decades long participation in the causality assessment committee meetings of the DILI Network.

RESULTS

DILI lacks a diagnostic test and is currently diagnosed through a process of exclusion of competing aetiologies of liver injury. This requires a high degree of suspicion to consider the possibility of DILI, skill in ruling out the obvious and less obvious competing liver insults, and an understanding of the expected phenotypes of DILI. The facets of DILI cover multiple aspects, including the latency, liver injury pattern, course of injury, and associated autoimmune or immuno-allergic features. Care for patients with DILI is geared towards stopping the offending drug and symptom management that include the use of corticosteroids in select cases.

CONCLUSION

The diagnosis of DILI is challenging and is primarily made through a carefully crafted patient interview, temporal relationship with the implicated drug or supplement, and exclusion of competing aetiology. LiverTox is a useful resource for clinicians to review the literature and recognise the likelihood of the implicated agent in causing DILI.

Toxicological assessment of SGLT2 inhibitors metabolites using in silico approach

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are the latest class of drugs approved to treat type 2 DM (T2DM). Although adverse effects are often caused by a metabolite rather than the drug itself, only the safety assessment of disproportionate drug metabolites is usually performed, which is of particular concern for drugs of chronic use, such as SGLT2i. Bearing this in mind, in silico tools are efficient strategies to reveal the risk assessment of metabolites, being endorsed by many regulatory agencies. Thereby, the goal of this study was to apply in silico methods to provide the metabolites toxicity assessment of the SGLT2i. Toxicological assessment from SGLT2i metabolites retrieved from the literature was estimated using the structure and/or statistical-based alert implemented in DataWarrior and ADMET predictorTM softwares. The drugs and their metabolites displayed no mutagenic, tumorigenic or cardiotoxic risks. Still, M1-2 and M3-1 were recognized as potential hepatotoxic compounds and M1-2, M1-3, M3-1, M3-2, M3-3 and M4-3, were estimated to have very toxic LD50 values in rats. All SGLT2i and the metabolites M3-4, M4-1 and M4-2, were predicted to have reproductive toxicity. These results support the awareness that metabolites may be potential mediators of drug-induced toxicities of the therapeutic agents.

Incidence and risk factors of drug-induced liver injury

The epidemiology and aetiology of drug-induced liver injury (DILI) vary across different countries and populations. Overall, DILI is rare in the general population but has become more prevalent in hospitalized patients, especially among patients with unexplained liver conditions. In addition, drugs implicated in DILI differ between Western and Eastern countries. Antibiotics are the leading drugs implicated in DILI in the West, whereas traditional Chinese medicine is the primary cause implicated in DILI in the East. The incidence of herbal and dietary supplements-induced hepatotoxicity is increasing globally. Several genetic and nongenetic risk factors associated with DILI have been described in the literature; however, there are no confirmed risk factors for all-cause DILI. Some factors may contribute to the risk of DILI in a drug-specific manner.

The role of cytokines, adhesion molecules, and toll-like receptors in atherosclerosis progression: the effect of Atorvastatin

Inflammatory cytokines, cell adhesion molecules, and toll-like receptors (TLRs) play an important role in atherosclerosis. The aim of this study was to further evaluate the role of inflammatory cytokines, cell adhesion molecules, and toll-like receptors in atherosclerosis. Forty local breed domestic male rabbits were divided randomly into 4 groups, 10 rabbits each. Group I was the control group, group II received a high cholesterol diet, group III received the drug solvent dimethyl sulfoxide (DMSO), and group IV received Atorvastatin (3.5 mg/kg/day). Blood samples were collected at 0 times, 5 weeks, and at the end of 10 weeks. TLRs expression on monocyte was measured by flow cytometry, IL-10, IL-17, IL-1β, intracellular adhesion molecule (ICAM), and vascular cell adhesion molecule (VCAM) were measured by ELISA. In group II, a high cholesterol diet led to a statistically significant elevation of lipids profile (TC, TG, and LDL) at both 5 weeks and 10 weeks compared to the control. The expression of TLRs was also increased compared to the control (13.53±2.5 to 25.79±6.5). The intimal thickness increased from 103.46±13.85 to 248.43±11.11. IL-17 increased significantly from 3.4±0.4 to 7.7±1.00, and IL-1β increased from 1.04±0.19 to 9.66±1.4 (P 0.05) at 10 weeks. ICAM and VCAM increased from 1.7±0.16 to 8.2±0.74 and from 0.89±0.07 to 5.2±0.45, respectively. Atorvastatin significantly reduced TLRs at 10 weeks to 21.98±3.4 and intimal thickness to 191.6±15.59. IL-17, IL-1β, ICAM, and VCAM were significantly reduced by Atorvastatin. Cytokines, cellular adhesion molecules, and probably TLRs have a role in the pathogenesis of hyperlipidemia and atherosclerosis.

Early Drug-Induced Liver Injury (DILI) Risk Screening: "Free", as good as it gets

For all the promise of and need for clinical drug-induced liver injury (DILI) risk screening systems, demonstrating the predictive value of these systems versus readily available physicochemical properties and inherent dosing information has not been thoroughly evaluated. Therefore, we utilized a systematic approach to evaluate the predictive value of in vitro safety assays including Bile Salt Export Pump (BSEP) transporter inhibition and cytotoxicity in HepG2 and transformed human liver epithelial (THLE) along with physicochemical properties. We also evaluated the predictive value of in vitro ADME assays including hepatic partition coefficient (Kp) and its unbound counterpart since they provide insight on hepatic accumulation potential. The datasets comprised of 569 marketed drugs with FDA DILIrank annotation (Most vs Less/None), dose and physicochemical information, 384 drugs with Kp and plasma protein binding data, and 279 drugs with safety assay data. For each dataset and combination of input parameters, we developed random forest machine learning models and measured model performance using the receiver operator characteristic area-under-the-curve (ROC AUC). The median ROC AUC across the various data and parameters sets ranged from 0.67 to 0.77 with little evidence of additive predictivity when including safety or ADME assay data. Subsequent machine learning models consistently demonstrated daily dose, fraction sp3 or ionization, and cLogP/D inputs produced the best, simplest model for predicting clinical DILI risk with an ROC AUC of 0.75. This systematic framework should be used for future assay predictive value assessments and highlights the need for continued improvements to clinical DILI risk annotation.

Study on the Characteristics of Small-Molecule Kinase Inhibitors-Related Drug-Induced Liver Injury

Background and Aim: More than half of the small-molecule kinase inhibitors (KIs) induced liver injury clinically. Meanwhile, studies have shown a close relationship between mitochondrial damage and drug-induced liver injury (DILI). We aimed to study KIs and the binding between drugs and mitochondrial proteins to find factors related to DILI occurrence.

Methods: A total of 1,223 oral FDA-approved drugs were collected and analyzed, including 44 KIs. Fisher’s exact test was used to analyze DILI potential and risk of different factors. A total of 187 human mitochondrial proteins were further collected, and high-throughput molecular docking was performed between human mitochondrial proteins and drugs in the data set. The molecular dynamics simulation was used to optimize and evaluate the dynamic binding behavior of the selected mitochondrial protein/KI complexes.

Results: The possibility of KIs to produce DILI is much higher than that of other types (OR = 46.89, p = 9.28E-13). A few DILI risk factors were identified, including molecular weight (MW) between 400 and 600, the defined daily dose (DDD) ≥ 100 mg/day, the octanol–water partition coefficient (LogP) ≥ 3, and the degree of liver metabolism (LM) more than 50%. Drugs that met this combination of rules were found to have a higher DILI risk than controls (OR = 8.28, p = 4.82E-05) and were more likely to cause severe DILI (OR = 8.26, p = 5.06E-04). The docking results showed that KIs had a significant higher affinity with human mitochondrial proteins (p = 4.19E-11) than other drug types. Furthermore, the five proteins with the lowest docking score were selected for molecular dynamics simulation, and the smallest fluctuation of the backbone RMSD curve was found in the protein 5FS8/KI complexes, which indicated the best stability of the protein 5FS8 bound to KIs.

Conclusions: KIs were found to have the highest odds ratio of causing DILI. MW was significantly related to the production of DILI, and the average docking scores of KI drugs were found to be significantly different from other classes. Further analysis identified the top binding mitochondrial proteins for KIs, and specific binding sites were analyzed. The optimization of molecular docking results by molecular dynamics simulation may contribute to further studying the mechanism of DILI.

Secular Trends in Severe Idiosyncratic Drug-Induced Liver Injury in North America: An Update From the Acute Liver Failure Study Group Registry

INTRODUCTION

Idiosyncratic drug-induced liver injury (DILI) is the second leading cause of acute liver failure (ALF) in the United States. Our study aims were to characterize secular trends in the implicated agents, clinical features, and outcomes of adults with DILI ALF over a 20-year period.

METHODS

Among 2,332 patients with ALF enrolled in the ALF Study Group registry, 277 (11.9%) were adjudicated as idiosyncratic DILI ALF (INR ≥ 1.5 and hepatic encephalopathy) through expert opinion. The 155 cases in era 1 (January 20, 1998-January 20, 2008) were compared with the 122 cases in era 2 (January 21, 2008-January 20, 2018).

RESULTS

Among 277 cases of DILI ALF, 97 different agents, alone or in combination, were implicated: antimicrobials, n = 118 (43%); herbal/dietary supplements (HDS), n = 42 (15%); central nervous system agents/illicit substances, n = 37 (13%); oncologic/biologic agents, n = 29 (10%); and other, n = 51 (18%). Significant trends over time included (i) an increase in HDS DILI ALF (9.7% vs 22%, P < 0.01) and decrease in antimicrobial-induced DILI ALF (45.8% vs. 38.5%, P = 0.03) and (ii) improved overall transplant-free survival (23.5%-38.7%, P < 0.01) while the number of patients transplanted declined (46.4% vs 33.6%, P < 0.03).

DISCUSSION

DILI ALF in North America is evolving, with HDS cases rising and other categories of suspect drugs declining. The reasons for a significant increase in transplant-free survival and reduced need for liver transplantation over time remain unclear but may be due to improvements in critical care, increased NAC utilization, and improved patient prognostication.

Drug-induced liver injury: Pathogenesis, epidemiology, clinical features, and practical management

Drug-induced liver injury (DILI) is an important but rare adverse event which can range from mild liver enzyme elevations to liver failure, transplantation or death. A large proportion of commonly used medications, in addition to herbal and dietary supplements, can cause liver injury. DILI has been categorized as direct or idiosyncratic but indirect liver injury has emerged as a third type of drug-induced liver injury. These types of liver injury may warrant different clinical approach and treatment. Associations of HLA genotypes and risk of DILI have highlighted the importance of the immune system in the pathogenesis of DILI. Furthermore, novel agents affecting the immune response can lead to liver injury, often associated with autoimmune features in serologic tests and liver biopsies. Overall, the diagnosis of DILI remains a challenge as it is requires detailed case evaluation in addition to reviewing the hepatotoxic potentials and clinical signatures of the implicated agents. Biochemical profiles vary between agents and although individual drugs tend to portray a consistent clinicopathologic signature, many drugs have multiple signatures. Thanks to multicenter prospective studies on DILI and websites in the public domain such as LiverTox, physicians are provided with tools to investigate suspected DILI cases to increase the likelihood of establishing adiagnosis. The pathogenesis of DILI, epidemiology and current challenges in the diagnosis and management of the disease are reviewed in the paper.

Relationships between the Structure and Severe Drug-Induced Liver Injury for Low, Medium, and High Doses of Drugs

Assessment of structure-activity relationships (SARs) for predicting severe drug-induced liver injury (DILI) is essential since in vivo and in vitro preclinical methods cannot detect many druglike compounds disrupting liver functions. To date, plenty of SAR models for the prediction of DILI have been developed; however, none of them considered the route of drug administration and daily dose, which may introduce significant bias into prediction results. We have created a dataset of 617 drugs with parenteral and oral administration routes and consistent information on DILI severity. We have found a clear relationship between route, dose, and DILI severity. According to SAR, nearly 40% of moderate- and non-DILI-causing drugs would cause severe DILI if they were administered at high oral doses. We have proposed the following approach to predict severe DILI. New compounds recommended to be used at low oral doses (<∼10 mg daily), or parenterally, can be considered not causing severe DILI. DILI for compounds administered at medium oral doses (∼10-100 mg daily; 22.2% of drugs under consideration) can be considered unpredictable because reasonable SAR models were not obtained due to the small size and heterogeneity of the corresponding dataset. The DILI potential of the compounds recommended to be used at high oral doses (more than ∼100 mg daily) can be estimated using SAR modeling. The balanced accuracy of the approach calculated by a 10-fold cross-validation procedure is 0.803. The developed approach can be used to estimate severe DILI for druglike compounds proposed to use at low and high oral doses or parenterally at the early stages of drug development.

Robust Pharmacodynamic Effect of LY3202626, a Central Nervous System Penetrant, Low Dose BACE1 Inhibitor, in Humans and Nonclinical Species

Background: The development of beta-site amyloid-beta precursor protein cleaving enzyme (BACE) 1 inhibitors for the treatment of Alzheimer’s disease requires optimization of inhibitor potency, selectivity, and brain penetration. Moreover, there is a need for low-dose compounds since liver toxicity was found with some BACE inhibitors. Objective: To determine whether the high in vitro potency and robust pharmacodynamic effect of the BACE inhibitor LY3202626 observed in nonclinical species translated to humans. Methods: The effect of LY3202626 versus vehicle on amyloid-β (Aβ) levels was evaluated in a series of in vitro assays, as well as in in vivo and multi-part clinical pharmacology studies. Aβ levels were measured using analytical biochemistry assays in brain, plasma, and cerebrospinal fluid (CSF) of mice, dogs and humans. Nonclinical data were analyzed using an ANOVA followed by Tukey’s post hoc test and clinical data used summary statistics. Results: LY3202626 exhibited significant human BACE1 inhibition, with an IC50 of 0.615±0.101 nM in a fluorescence resonance energy transfer assay and an EC50 of 0.275±0.176 nM for lowering Aβ1–40 and 0.228±0.244 nM for Aβ1–42 in PDAPP neuronal cultures. In dogs, CSF Aβ1hboxx concentrations were significantly reduced by ∼80% at 9 hours following a 1.5 mg/kg dose. In humans, CSF Aβ1–42 was reduced by 73.1±7.96 % following administration of 6 mg QD. LY3202626 was found to freely cross the blood-brain barrier in dogs and humans. Conclusion: LY3202626 is a potent BACE1 inhibitor with high blood-brain barrier permeability. The favorable safety and pharmacokinetic/pharmacodynamic profile of LY3202626 supports further clinical development.

Utilization and Impact of Complementary and Alternative Medicines in Symptomatic Autoimmune Hepatitis Patients

BACKGROUND

Complementary and alternative medicine (CAM) use has become increasingly common. It is also prevalent in patients with chronic liver disease, but the scope, depth, and safety of use is not well known.

AIMS

This study aimed to evaluate the prevalence and patterns of CAM use in autoimmune hepatitis (AIH) patients.

METHODS

Electronic invitation to complete a 22 item CAM-specific questionnaire was posted weekly to well-established AIH Facebook communities (combined membership of 4700 individuals) during a 6-week study period. Age ≥ 18 years and AIH diagnosis made by a treating physician were the eligibility criteria.

RESULTS

The prevalence of ever CAM use among participants was 56.4%, and nearly 42% used CAM after AIH diagnosis. Among those reporting CAM use after diagnosis, 53.7% (51/95) indicated CAM was used to mitigate AIH-related phenomenon, most often targeting liver inflammation/fibrosis (67.7%), fatigue (51%), joint pain (47.1%), and sleep issues (45.1%). Most frequent physical CAM strategies were exercise (49.5%) and yoga (34%), whereas most frequent consumable CAM included healthier eating (45.3%), cannabidiol preparations (45.3%), and probiotics (44.3%). Seventy-five percent reported that CAM improved AIH symptoms and no severe adverse events were reported.

CONCLUSIONS

CAM use in AIH patients is prevalent, yet providers have historically failed to document their patient's CAM strategies. Beyond inherent drug-induced liver injury risk, drug-drug interactions remain a concern and could alter baseline immunosuppression levels in AIH. Despite a majority found CAM approaches that improved targeted symptoms, all were unable to alter the course of chronically prescribed medications by physicians.

Comprehensive in Vitro Characterization of the LSD1 Small Molecule Inhibitor Class in Oncology

Lysine-specific demethylase 1 (LSD1 or KDM1A) is a chromatin modifying enzyme playing a key role in the cell cycle and cell differentiation and proliferation through the demethylation of histones and nonhistone substrates. In addition to its enzymatic activity, LSD1 plays a fundamental scaffolding role as part of transcription silencing complexes such as rest co-repressor (CoREST) and nucleosome remodeling and deacetylase (NuRD). A host of classical amine oxidase inhibitors such as tranylcypromine, pargyline, and phenelzine together with LSD1 tool compounds such as SP-2509 and GSK-LSD1 have been extensively utilized in LSD1 mechanistic cancer studies. Additionally, several optimized new chemical entities have reached clinical trials in oncology such as ORY-1001 (iadademstat), GSK2879552, SP-2577 (seclidemstat), IMG-7289 (bomedemstat), INCB059872, and CC-90011 (pulrodemstat). Despite this, no single study exists that characterizes them all under the same experimental conditions, preventing a clear interpretation of published results. Herein, we characterize the whole LSD1 small molecule compound class as inhibitors of LSD1 catalytic activity, disruptors of SNAIL/GFI1 (SNAG)-scaffolding protein-protein interactions, inducers of cell differentiation, and potential anticancer treatments for hematological and solid tumors to yield an updated, unified perspective of this field. Our results highlight significant differences in potency and selectivity among the clinical compounds with iadademstat being the most potent and reveal that most of the tool compounds have very low activity and selectivity, suggesting some conclusions derived from their use should be taken with caution.

Regulation of the immune tolerance system determines the susceptibility to HLA-mediated abacavir-induced skin toxicity

Idiosyncratic drug toxicity (IDT) associated with specific human leukocyte antigen (HLA) allotype is a rare and unpredictable life-threatening adverse drug reaction for which prospective mechanistic studies in humans are difficult. Here, we show the importance of immune tolerance for IDT onset and determine whether it is susceptible to a common IDT, HLA-B*57:01-mediated abacavir (ABC)-induced hypersensitivity (AHS), using CD4⁺ T cell-depleted programmed death-1 receptor (PD-1)-deficient HLA-B*57:01 transgenic mice (B*57:01-Tg/PD-1^−/−). Although AHS is not observed in B*57:01-Tg mice, ABC treatment increases the proportion of cytokine- and cytolytic granule-secreting effector memory CD8⁺ T cells in CD4⁺ T cell-depleted B*57:01-Tg/PD-1^−/− mice, thereby inducing skin toxicity with CD8⁺ T cell infiltration, mimicking AHS. Our results demonstrate that individual differences in the immune tolerance system, including PD-1^highCD8⁺ T cells and regulatory CD4⁺ T cells, may affect the susceptibility of humans to HLA-mediated IDT in humans.

Using a transgenic mouse model that recapitulates abacavir hypersensitivity syndrome, an idiosyncratic adverse drug reaction, Susukida et al show that individual differences in the immune tolerance system affect the susceptibility to idiosyncratic drug toxicity.

Utilization of Metabolite Identification and Structural Data to Guide Design of Low-Dose IDO1 Inhibitors

Herein the discovery of potent IDO1 inhibitors with low predicted human dose is discussed. Metabolite identification (MetID) and structural data were used to strategically incorporate cyclopropane rings into this tetrahydronaphthyridine series of IDO1 inhibitors to improve their metabolic stability and potency. Enabling synthetic chemistry was developed to construct these unique fused cyclopropyl compounds, leading to inhibitors with improved pharmacokinetics and human whole blood potency and a predicted human oral dose as low as 9 mg once daily (QD).

Fluorovinylsulfones and -Sulfonates as Potent Covalent Reversible Inhibitors of the Trypanosomal Cysteine Protease Rhodesain: Structure-Activity Relationship, Inhibition Mechanism, Metabolism, and In Vivo Studies

Rhodesain is a major cysteine protease of Trypanosoma brucei rhodesiense, a pathogen causing Human African Trypanosomiasis, and a validated drug target. Recently, we reported the development of α-halovinylsulfones as a new class of covalent reversible cysteine protease inhibitors. Here, α-fluorovinylsulfones/-sulfonates were optimized for rhodesain based on molecular modeling approaches. 2d, the most potent and selective inhibitor in the series, shows a single-digit nanomolar affinity and high selectivity toward mammalian cathepsins B and L. Enzymatic dilution assays and MS experiments indicate that 2d is a slow-tight binder (K_i = 3 nM). Furthermore, the nonfluorinated 2d-(H) shows favorable metabolism and biodistribution by accumulation in mice brain tissue after intraperitoneal and oral administration. The highest antitrypanosomal activity was observed for inhibitors with an N-terminal 2,3-dihydrobenzo[b][1,4]dioxine group and a 4-Me-Phe residue in P2 (2e/4e) with nanomolar EC₅₀ values (0.14/0.80 μM). The different mechanisms of reversible and irreversible inhibitors were explained using QM/MM calculations and MD simulations.

Identification of average molecular weight (AMW) as a useful chemical descriptor to discriminate liver injury-inducing drugs

Drug-induced liver injury (DILI) is one of major causes of discontinuing drug development and withdrawing drugs from the market. In this study, we investigated chemical properties associated with DILI using in silico methods, to identify a physicochemical property useful for DILI screening at the early stages of drug development. Total of 652 drugs, including 432 DILI-positive drugs (DILI drugs) and 220 DILI-negative drugs (no-DILI drugs) were selected from Liver Toxicity Knowledge Base of US Food and Drug Administration. Decision tree models were constructed using 2,473 descriptors as explanatory variables. In the final model, the descriptor AMW, representing average molecular weight, was found to be at the first node and showed the highest importance value. With AMW alone, 276 DILI drugs (64%) and 156 no-DILI drugs (71%) were correctly classified. Discrimination with AMW was then performed using therapeutic category information. The performance of discrimination depended on the category and significantly high performance (>0.8 balanced accuracy) was obtained in some categories. Taken together, the present results suggest AMW as a novel descriptor useful for detecting drugs with DILI risk. The information presented may be valuable for the safety assessment of drug candidates at the early stage of drug development.

Hepatoxicity Induced by Clozapine: Case Report and Brief Review

INTRODUCTION

Antipsychotics are drugs that can produce transient elevations of hepatic enzymes. Clozapine is an atypical antipsychotic used in treatment-resistant schizophrenia and there is evidence that it can produce elevations of hepatic transaminases, expression of liver damage in a hepatocellular pattern.

METHODS

Case report and non-systematic review of the relevant literature.

CASE PRESENTATION

A 39-year-old woman with a diagnosis of paranoid schizophrenia attended the emergency department of a general hospital for nausea, vomiting and jaundice that appeared after the initiation of clozapine. There was no clinical improvement during hospitalisation, and death occurred after 44 days.

LITERATURE REVIEW

Clozapine can increase the liver enzyme levels transiently and asymptomatically; however, there are clinical criteria that recommend the withdrawal of the antipsychotic.

CONCLUSIONS

This is the third case reported in the literature of a fatal outcome of clozapine-induced hepatotoxicity.

Liver injury associated with the use of selective androgen receptor modulators and post-cycle therapy: Two case reports and literature review

BACKGROUND

Muscle growth promoters are being developed for the treatment of disease-induced loss of muscle mass. Ligandrol and ostarine are selective androgen receptor modulators (SARMs) with a non-steroidal structure and a presumably more favorable side effect profile. In recent years, these substances with or without “post-cycle therapy” (PCT) are often misused by amateur athletes aiming to promote muscle growth. At the same time, reports on their toxic effects on organ systems are emerging.

CASE SUMMARY

We report two cases of liver injury in young men who used ligandrol and/or ostarine for a few weeks followed by the use of substances for PCT. Acute liver injury occurred in both cases after stopping SARMs while on PCT. The clinical picture was dominated by jaundice and fatigue. The biochemical pattern showed a mixed type of injury with normal alkaline phosphatase and high concentrations of bilirubin and serum bile acids. Histological evidence showed predominantly cholestatic injury with canalicular bile plugs, ductopenia, and mild hepatocellular damage without significant fibrosis. The patients recovered from the condition after 3 mo. The off target effects of SARMs were likely idiosyncratic, but our report highlights the yet unrecognized effects of other toxic substances used for PCT, supra-therapeutic doses, and the complete absence of monitoring for adverse effects.

CONCLUSION

Among muscle-building amateur athletes, SARMs (ligandrol or ostarine) and/or substances in PCT may cause cholestatic liver injury with prolonged recovery.

Discovery and Early Clinical Development of LY3202626, a Low-Dose, CNS-Penetrant BACE Inhibitor

The beta-site APP cleaving enzyme 1, known as BACE1, has been a widely pursued Alzheimer's disease drug target owing to its critical role in the production of amyloid-beta. We have previously reported the clinical development of LY2811376 and LY2886721. LY2811376 advanced to Phase I before development was terminated due to nonclinical retinal toxicity. LY2886721 advanced to Phase II, but development was halted due to abnormally elevated liver enzymes. Herein, we report the discovery and clinical development of LY3202626, a highly potent, CNS-penetrant, and low-dose BACE inhibitor, which successfully addressed these key development challenges.

Mechanistic insights into antiretroviral drug-induced liver injury

All classes of antiretroviral therapy (ART) have been implicated to induce adverse drug reactions such drug-induced liver injury (DILI) and immune-mediated adverse reactions in Human Immunodeficiency Virus (HIV) infected individuals. Patients that develop adverse drug reactions tend to have prolonged stays in hospital and may require to change to alternative regimens if reactions persist upon rechallenge or if rechallenge is contraindicated due to severity of the adverse reaction. Diagnosis of DILI remains a huge obstacle that delays timely interventions, since it is still based largely on exclusion of other causes. There is an urgent need to develop robust diagnostic and predictive biomarkers that could be used alongside the available tools (biopsy, imaging, and serological tests for liver enzymes) to give a specific diagnosis of DILI. Crucial to this is also achieving consensus in the definition of DILI so that robust studies can be undertaken. Importantly, it is crucial that we gain deeper insights into the mechanism of DILI so that patients can receive appropriate management. In general, it has been demonstrated that the mechanism of ART-induced liver injury is driven by four main mechanisms: mitochondrial toxicity, metabolic host-mediated injury, immune reconstitution, and hypersensitivity reactions. The focus of this review is to discuss the type and phenotypes of DILI that are caused by the first line ART regimens. Furthermore, we will summarize recent studies that have elucidated the cellular and molecular mechanisms of DILI both in vivo and in vitro.

Severe drug-induced liver injury in patients under treatment with antipsychotic drugs: Data from the AMSP study

OBJECTIVES

Drug-induced liver injury (DILI) has been associated with various antipsychotic drugs (APDs). Comparative studies between individual APDs are largely not available.

METHODS

Antipsychotic drug utilisation data and reports of severe antipsychotic DILI were assessed by using data from an observational pharmacovigilance programme-Arzneimittelsicherheit in der Psychiatrie (AMSP)-during the period 1993-2016.

RESULTS

Of the 333,175 patients treated with APDs, a total of 246 (0.07%) events of severe DILI were identified. Phenothiazines were associated with significantly higher rates of severe DILI (0.03%, 95% CI = 0.02-0.04) than thioxanthenes (0.01%, 95% CI = 0.00-0.02) or butyrophenones (0.01%, 95% CI = 0.00-0.01). Among individual drugs, olanzapine (0.12%, 95% CI = 0.10-0.16), perazine (0.09%, 95% CI = 0.05-0.15) and clozapine (0.09%, 95% CI = 0.10-0.12 ranked highest. In 78 cases (31.7%), combination therapies with antipsychotic and antidepressant drugs or with two or more APDs were considered responsible. Male sex and a diagnosis of mania were associated with significantly higher rates of severe DILI while older patients (≥65 years old) were significantly less often affected.

CONCLUSIONS

In the present analysis of a representative psychiatric inpatient cohort, olanzapine, perazine, and clozapine were the most common individual APDs associated with severe DILI.

Drug-induced Bile Duct Injury - A Short Review

The liver represents the major site of drug metabolism, i.e. the key organ in the processes of detoxification and elimination of drugs from the organism. It is therefore often affected by toxic metabolites and suffers sometimes fatal consequences. The spectrum of pathologies differs by the cell type primarily damaged and the group of the cholangiopathies includes those conditions affecting the bile duct epithelium or the cholangiocytes. They can range from transient cholestasis to vanishing bile duct syndrome and sclerosing cholangitis, both leading eventually to the development of biliary fibrosis and cirrhosis. In this review article, we focus on the etiology, predisposing factors, clinical manifestations, and histopathological characteristics of bile duct injury as a consequence of drug treatment and discuss separately the different bile duct pathologies.

Second-Generation Cephalosporins-Associated Drug-Induced Liver Disease: A Study in VigiBase with a Focus on the Elderly

Background: The objective of this study was to characterize individual case safety reports (ICSRs) and adverse drug reactions (ADRs) related to second-generation cephalosporins and resulting in hepatobiliary disorders, in VigiBase, WHO global database. Methods: All second-generation cephalosporins hepatobiliary ADRs reported up to July 2019 were included. Characteristic of cephalosporins and ADRs, aside from disproportionality data were evaluated. Results: A total of 1343 ICSRs containing 1585 ADRs were analyzed. Cefuroxime was suspected to have caused hepatobiliary disorders in most cases—in 38% of adults and in 35% of elderly. Abnormal hepatic function was the most frequent ADR, followed by jaundice and hepatitis. For 49% of the ADRs reported in the elderly and 51% in the adult population, the outcome was favorable, with fatal outcome for 2% of the adults and 10% of the elderly. Higher proportional reporting ration (PRR) values were reported in the elderly for cefotetan-associated jaundice, cefuroxime-associated acute hepatitis and hepatitis cholestatic as well as for cefotiam and cefmetazole-associated liver disorder. Conclusion: Hepatobiliary ADRs were reported for 2nd generation cephalosporins, with over 50% of cases in adults, without gender differences. Cholestatic hepatitis was predominately reported in the elderly and this category was more prone to specific hepatic reactions.

Immune-Mediated Drug-Induced Liver Injury: Immunogenetics and Experimental Models

Drug-induced liver injury (DILI) is a challenging clinical event in medicine, particularly because of its ability to present with a variety of phenotypes including that of autoimmune hepatitis or other immune mediated liver injuries. Limited diagnostic and therapeutic tools are available, mostly because its pathogenesis has remained poorly understood for decades. The recent scientific and technological advancements in genomics and immunology are paving the way for a better understanding of the molecular aspects of DILI. This review provides an updated overview of the genetic predisposition and immunological mechanisms behind the pathogenesis of DILI and presents the state-of-the-art experimental models to study DILI at the pre-clinical level.

Pharmacokinetics, toxicological and clinical aspects of ulipristal acetate: insights into the mechanisms implicated in the hepatic toxicity

Ulipristal acetate is a drug used as emergency contraceptive (30 mg) and for the treatment of moderate to severe symptoms of uterine myomas (5 mg). After commercialization, and although the exact number is unknown, serious cases implying ulipristal acetate 5 mg as a contributing factor of liver injury, some leading to transplantation, were reported. These cases prompted to a restrict use of the drug in January 2021 by the European Medicines Agency. This work aimed to fully review pharmacokinetic aspects, namely focusing in the ulipristal acetate metabolism and other hypothetical toxicological underlying mechanisms that may predispose to drug-induced liver injury (DILI). The high lipophilicity, the extensive hepatic metabolism, the long half-life of the drug and of its major active metabolite, the long-term course of treatment, and possibility due to the formation of epoxide reactive may be contributing factors. Scientific results also points evidence to consider monitorization of liver function during ulipristal acetate treatment.

Idiosyncratic Drug Induced Liver Injury, Cytochrome P450, Metabolic Risk Factors and Lipophilicity: Highlights and Controversies

Progress in understanding the mechanisms of the idiosyncratic drug induced liver injury (iDILI) was highlighted in a scientometric investigation on the knowledge mapping of iDILI throughout the world, but uncertainty remained on metabolic risk factors of iDILI, the focus of the present review article. For the first time, a quantitative analysis of 3312 cases of iDILI assessed for causality with RUCAM (Roussel Uclaf Causality Assessment Method) showed that most drugs (61.1%) were metabolized by cytochrome P450 (CYP) isoforms: 49.6% by CYP 3A4/5, 24.6% by CYP 2C9, 13.2% by CYP 2E1, 7.3% by CYP 2C19, 3.5% by CYP 1A2 and 1.8% by CYP 2D6. Other studies showed high OR (odds ratio) for drugs metabolized by unspecified CYPs but the iDILI cases were not assessed for causality with RUCAM, a major shortcoming. In addition to critical comments on methodological flaws, several risk factors of iDILI were identified such as high but yet recommended daily drug doses, actual daily drug doses taken by the patients, hepatic drug metabolism and drug lipophilicity. These risk factors are subject to controversies by many experts seen critically also by others who outlined that none of these medication characteristics is able to predict iDILI with high confidence, leading to the statement of an outstanding caveat. It was also argued that all previous studies lacked comprehensive data because the number of examined drugs was relatively small as compared to the number of approved new molecular entities or currently used oral prescription drugs. In conclusion, trends are evident that some metabolic parameters are likely risk factors of iDILI but strong evidence can only be achieved when methodological issues will be successfully met.

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.

Sunitinib-Induced Acute Liver Failure

Drug-induced liver injury is an uncommon but life-threatening entity. Sunitinib is a tyrosine kinase inhibitor used for advanced and imatinib-refractory gastrointestinal stromal tumors. It causes transient elevation in liver enzymes. The incidence of fatal acute liver failure is rare. Five cases of sunitinib-induced acute liver injury have been reported in the literature thus far. We present a case of fatal acute liver failure and cardiomyopathy within 2 weeks of sunitinib therapy initiation for advanced pancreatic neuroendocrine carcinoma. We believe our case is unique due to the rarity of its presentation. It highlights hepatotoxicity as a potentially fatal side effect of sunitinib therapy.

Medical Therapy for Fibroids: What Next for Ulipristal Acetate?

Ulipristal acetate (UPA) was introduced as a novel progesterone receptor modulator as effective therapy for symptomatic fibroids. Randomised clinical trials established its effectiveness in the management of heavy menstrual bleeding due to uterine leiomyomas. The trials did not find any significant evidence of clinical harm to the participants. Recently, however, there have been reports of liver injury necessitating liver transplant in women who have had UPA treatment. This has led to the suspension of UPA as one of the medical therapies in the treatment for uterine fibroids while the European Medicines Agency (EMA) conducts a review of liver injury risk with its use. The European Medicine Agency safety committee has advised that women should stop taking 5 mg UPA and that no new patients should commence treatment with the medicine until the ongoing review is completed. In this article, we review the rise of UPA as one of the emerging medical therapies for symptomatic uterine fibroids and the subsequent reports of adverse events leading to the suspension of its use.

Pexidartinib Long-Term Hepatic Safety Profile in Patients with Tenosynovial Giant Cell Tumors

Background

Pexidartinib is approved in the U.S. for tenosynovial giant cell tumors (TGCTs). Herein, we assessed the hepatic safety profile of pexidartinib across patients with TGCTs receiving pexidartinib.

Materials, and Methods

Hepatic adverse reactions (ARs) were assessed by type and magnitude of liver test abnormalities, classified as (a) isolated aminotransferase elevations (alanine [ALT] or aspartate [AST], without significant alkaline phosphatase [ALP] or bilirubin elevations), or (b) mixed or cholestatic hepatotoxicity (increase in ALP with or without ALT/AST and bilirubin elevations, based on adjudication). Median follow‐up from initial pexidartinib treatment was 39 months (range, 32–82) in 140 patients with TGCTs across clinical studies NCT01004861, NCT02371369, NCT02734433, and NCT03291288.

Results

In total, 95% of patients with TGCTs (133/140) treated with pexidartinib (median duration of exposure, 19 months [range, 1–76]), experienced a hepatic AR. A total of 128 patients (91%) had reversible, low‐grade dose‐dependent isolated AST/ALT elevations without significant ALP elevations. Five patients (4%) experienced serious mixed or cholestatic injury. No case met Hy's law criteria. Onset of hepatic ARs was predominantly in the first 2 months. All five serious hepatic AR cases recovered 1–7 months following pexidartinib discontinuation. Five patients from the non‐TGCT population (N = 658) experienced serious hepatic ARs, two irreversible cases.

Conclusion

This pooled analysis provides information to help form the basis for the treating physician's risk assessment for patients with TCGTs, a locally aggressive but typically nonmetastatic tumor. In particular, long‐term treatment with pexidartinib has a predictable effect on hepatic aminotransferases and unpredictable risk of serious cholestatic or mixed liver injury.

Implications for Practice

This is the first long‐term pooled analysis to report on the long‐term hepatic safety of pexidartinib in patients with tenosynovial giant cell tumors associated with severe morbidity or functional limitations and not amenable to improvement with surgery. These findings extend beyond what has been previously published, describing the observed instances of hepatic toxicity following pexidartinib treatment across the clinical development program. This information is highly relevant for medical oncologists and orthopedic oncologists and provides guidance for its proper use for appropriate patients within the Pexidartinib Risk Evaluation and Mitigation Safety program.

Pexidartinib is approved in the U.S. for treatment of tenosynovial giant cell tumors (TGCT). This article assesses the hepatic safety profile of pexidartinib in TGCT cases and describes risk mitigation procedures designed to identify any instances of serious liver injury as early as possible to better inform prescribers and patients about this drug.

Approaches to mitigate the risk of serious adverse reactions in covalent drug design

INTRODUCTION

Covalent inhibition of target proteins using high affinity ligands bearing weakly electrophilic warheads is being adopted increasingly as design strategy in the discovery of novel therapeutics, and several covalent drugs have now received regulatory approval for indications in oncology. Experience to date with targeted covalent inhibitors has led to a number of design principles that underlie the safety and efficacy of this increasingly important class of molecules.

AREAS COVERED

A review is provided of the current status of the covalent drug approach, emphasizing the unique benefits and attendant risks associated with reversible and irreversible binders. Areas of application beyond inhibition of tyrosine kinases are presented, and design considerations to de-risk covalent inhibitors with respect to undesirable off-target effects are discussed.

EXPERT OPINION

High selectivity for the intended protein target has emerged as a key consideration in mitigating safety risks associated with widespread proteome reactivity. Powerful chemical proteomics-based techniques are now available to assess selectivity in a drug discovery setting. Optimizing pharmacokinetics to capitalize on the intrinsically high potency of covalent drugs should lead to low daily doses and greater safety margins, while minimizing susceptibility to metabolic activation likewise will attenuate the risk of covalent drug toxicity.

Worldwide Use of RUCAM for Causality Assessment in 81,856 Idiosyncratic DILI and 14,029 HILI Cases Published 1993-Mid 2020: A Comprehensive Analysis

Background: A large number of idiosyncratic drug induced liver injury (iDILI) and herb induced liver injury(HILI) cases of variable quality has been published but some are a matter of concern if the cases were not evaluated for causality using a robust causality assessment method (CAM) such as RUCAM (Roussel Uclaf Causality Assessment Method) as diagnostiinjuryc algorithm. The purpose of this analysis was to evaluate the worldwide use of RUCAM in iDILI and HILI cases. Methods: The PubMed database (1993-30 June 2020) was searched for articles by using the following key terms: Roussel Uclaf Causality Assessment Method; RUCAM; Idiosyncratic drug induced liver injury; iDILI; Herb induced liver injury; HILI. Results: Considering reports published worldwide since 1993, our analysis showed the use of RUCAM for causality assessment in 95,885 cases of liver injury including 81,856 cases of idiosyncratic DILI and 14,029 cases of HILI. Among the top countries providing RUCAM based DILI cases were, in decreasing order, China, the US, Germany, Korea, and Italy, with China, Korea, Germany, India, and the US as the top countries for HILI. Conclusion: Since 1993 RUCAM is certainly the most widely used method to assess causality in IDILI and HILI. This should encourage practitioner, experts, and regulatory agencies to use it in order to reinforce their diagnosis and to take sound decisions.