Evaluation of PXL065 - deuterium-stabilized (R)-pioglitazone in patients with NASH: A phase II randomized placebo-controlled trial (DESTINY-1)

EASL-EASD-EASO Clinical Practice Guidelines on the Management of Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously termed non-alcoholic fatty liver disease (NAFLD), is defined as steatotic liver disease (SLD) in the presence of one or more cardiometabolic risk factor(s) and the absence of harmful alcohol intake. The spectrum of MASLD includes steatosis, metabolic dysfunction-associated steatohepatitis (MASH, previously NASH), fibrosis, cirrhosis and MASH-related hepatocellular carcinoma (HCC). This joint EASL-EASD-EASO guideline provides an update on definitions, prevention, screening, diagnosis and treatment for MASLD. Case-finding strategies for MASLD with liver fibrosis, using non-invasive tests, should be applied in individuals with cardiometabolic risk factors, abnormal liver enzymes, and/or radiological signs of hepatic steatosis, particularly in the presence of type 2 diabetes (T2D) or obesity with additional metabolic risk factor(s). A stepwise approach using blood-based scores (such as FIB-4) and, sequentially, imaging techniques (such as transient elastography) is suitable to rule-out/in advanced fibrosis, which is predictive of liver-related outcomes. In adults with MASLD, lifestyle modification - including weight loss, dietary changes, physical exercise and discouraging alcohol consumption - as well as optimal management of comorbidities - including use of incretin-based therapies (e.g. semaglutide, tirzepatide) for T2D or obesity, if indicated - is advised. Bariatric surgery is also an option in individuals with MASLD and obesity. If locally approved and dependent on the label, adults with non-cirrhotic MASH and significant liver fibrosis (stage ≥2) should be considered for a MASH-targeted treatment with resmetirom, which demonstrated histological effectiveness on steatohepatitis and fibrosis with an acceptable safety and tolerability profile. No MASH-targeted pharmacotherapy can currently be recommended for the cirrhotic stage. Management of MASH-related cirrhosis includes adaptations of metabolic drugs, nutritional counselling, surveillance for portal hypertension and HCC, as well as liver transplantation in decompensated cirrhosis.

EASL-EASD-EASO Clinical Practice Guidelines on the management of metabolic dysfunction-associated steatotic liver disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously termed non-alcoholic fatty liver disease (NAFLD), is defined as steatotic liver disease (SLD) in the presence of one or more cardiometabolic risk factor(s) and the absence of harmful alcohol intake. The spectrum of MASLD includes steatosis, metabolic dysfunction-associated steatohepatitis (MASH, previously NASH), fibrosis, cirrhosis and MASH-related hepatocellular carcinoma (HCC). This joint EASL-EASD-EASO guideline provides an update on definitions, prevention, screening, diagnosis and treatment for MASLD. Case-finding strategies for MASLD with liver fibrosis, using non-invasive tests, should be applied in individuals with cardiometabolic risk factors, abnormal liver enzymes, and/or radiological signs of hepatic steatosis, particularly in the presence of type 2 diabetes (T2D) or obesity with additional metabolic risk factor(s). A stepwise approach using blood-based scores (such as FIB-4) and, sequentially, imaging techniques (such as transient elastography) is suitable to rule-out/in advanced fibrosis, which is predictive of liver-related outcomes. In adults with MASLD, lifestyle modification - including weight loss, dietary changes, physical exercise and discouraging alcohol consumption - as well as optimal management of comorbidities - including use of incretin-based therapies (e.g. semaglutide, tirzepatide) for T2D or obesity, if indicated - is advised. Bariatric surgery is also an option in individuals with MASLD and obesity. If locally approved and dependent on the label, adults with non-cirrhotic MASH and significant liver fibrosis (stage ≥2) should be considered for a MASH-targeted treatment with resmetirom, which demonstrated histological effectiveness on steatohepatitis and fibrosis with an acceptable safety and tolerability profile. No MASH-targeted pharmacotherapy can currently be recommended for the cirrhotic stage. Management of MASH-related cirrhosis includes adaptations of metabolic drugs, nutritional counselling, surveillance for portal hypertension and HCC, as well as liver transplantation in decompensated cirrhosis.

Obesity and MASLD: Is weight loss the (only) key to treat metabolic liver disease?

Metabolic dysfunction-associated steatotic liver disease (MASLD) closely associates with obesity and type 2 diabetes. Lifestyle intervention and bariatric surgery aiming at substantial weight loss are cornerstones of MASLD treatment by improving histological outcomes and reducing risks of comorbidities. Originally developed as antihyperglycemic drugs, incretin (co-)agonists and SGLT2 inhibitors also reduce steatosis and cardiorenovascular events. Certain incretin agonists effectively improve histological features of MASLD, but not fibrosis. Of note, beneficial effects on MASLD may not necessarily require weight loss. Despite moderate weight gain, one PPARγ agonist improved adipose tissue and MASLD with certain benefit on fibrosis in post-hoc analyses. Likewise, the first THRβ-agonist was recently provisionally approved because of significant improvements of MASLD and fibrosis. We here discuss liver-related and metabolic effects induced by different MASLD treatments and their association with weight loss. Therefore, we compare results from clinical trials on drugs acting via weight loss (incretin (co)agonists, SGLT2 inhibitors) with those exerting no weight loss (pioglitazone; resmetirom). Furthermore, other drugs in development directly targeting hepatic lipid metabolism (lipogenesis inhibitors, FGF21 analogs) are addressed. Although THRβ-agonism may effectively improve hepatic outcomes, MASLD treatment concepts should consider all cardiometabolic risk factors for effective reduction of morbidity and mortality in the affected people.

Epidemiology, screening, and co-management of type 2 diabetes mellitus and metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as NAFLD, is increasingly recognized as a prevalent global burden. Type 2 diabetes mellitus (T2DM), another important metabolic disease, is considered a major contributor to the development of MASLD. MASLD and T2DM have a strong association with each other due to shared pathogenic mechanisms. The co-existence of the 2 diseases increases the risk of liver-related adverse outcomes and imposes a heavier burden on extrahepatic outcomes, representing a substantial public health issue. Effective assessment and management of T2DM combined with MASLD necessitate a multidisciplinary approach. The emergence of numerous RCTs has shed light on the treatment of T2DM combined with MASLD. This review uncovers the epidemiology of the intertwined T2DM and MASLD, offers insights into the evaluation of hepatic fibrosis in patients with T2DM, glucose monitoring in the MASLD population, and provides comprehensive co-management strategies for addressing both diseases.

New and emerging treatments for metabolic dysfunction-associated steatohepatitis

Metabolic dysfunction-associated steatohepatitis (MASH) is a leading etiology of chronic liver disease worldwide, with increasing incidence and prevalence in the setting of the obesity epidemic. MASH is also a leading indication for liver transplantation, given its associated risk of progression to end-stage liver disease. A key challenge in managing MASH is the lack of approved pharmacotherapy. In its absence, lifestyle interventions with a focus on healthy nutrition and regular physical activity have been the cornerstone of therapy. Real-world efficacy and sustainability of lifestyle interventions are low, however. Pharmacotherapy development for MASH is emerging with promising data from several agents with different mechanisms of action (MOAs) in phase 3 clinical trials. In this review, we highlight ongoing challenges and potential solutions in drug development for MASH and provide an overview of available data from emerging therapies across multiple MOAs.

Advancements in pharmacological treatment of NAFLD/MASLD: a focus on metabolic and liver-targeted interventions

In the present narrative review, we have summarized evidence on the pharmacological treatment of non-alcoholic fatty liver disease (NAFLD)/metabolic dysfunction-associated steatotic liver disease (MASLD). We start by reviewing the epidemiology of the condition and its close association with obesity and type 2 diabetes. We then discuss how randomized-controlled trials are performed following guidance from regulatory agencies, including differences and similarities between requirements of the US Food and Drug Administration and the European Medicine Agency. Difficulties and hurdles related to limitations of liver biopsy, a large number of screening failures in recruiting patients, as well as unpredictable response rates in the placebo group are evaluated. Finally, we recapitulate the strategies employed for potential drug treatments of this orphan condition. The first is to repurpose drugs that originally targeted T2DM and/or obesity, such as pioglitazone, glucagon-like peptide 1 receptor agonists (liraglutide and semaglutide), multi-agonists (tirzepatide and retatrutide), and sodium-glucose transporter 2 inhibitors. The second is to develop drugs specifically targeting NAFLD/MASLD. Among those, we focused on resmetirom, fibroblast growth factor 21 analogs, and lanifibranor, as they are currently in Phase 3 of their clinical trial development. While many failures have characterized the field of pharmacological treatment of NAFLD/MASLD in the past, it is likely that approval of the first treatments is near. As occurs in many chronic conditions, combination therapy might lead to better outcomes. In the case of non-alcoholic steatohepatitis, we speculate that drugs treating underlying metabolic co-morbidities might play a bigger role in the earlier stages of disease, while liver-targeting molecules will become vital in patients with more advanced disease in terms of inflammation and fibrosis.

Hepatic mitochondrial reductive stress in the pathogenesis and treatment of steatotic liver disease

Steatotic liver diseases (SLDs) affect one-third of the population, but the pathogenesis underlying these diseases is not well understood, limiting the available treatments. A common factor in SLDs is increased hepatic mitochondrial reductive stress, which occurs as a result of excessive lipid and alcohol metabolism. Recent research has also shown that genetic risk factors contribute to this stress. This review aims to explore how these risk factors increase hepatic mitochondrial reductive stress and how it disrupts hepatic metabolism, leading to SLDs. Additionally, the review will discuss the latest clinical studies on pharmaceutical treatments for SLDs, specifically peroxisome proliferator-activated receptor gamma (PPAR-γ) agonists, thyroid hormone receptor (THR) agonists, acetyl-CoA carboxylase (ACC) inhibitors, and mitochondrial uncouplers. These treatments have a common effect of decreasing hepatic mitochondrial reductive stress, which has been largely overlooked.

Physiologically Based Pharmacokinetic (PBPK) Model Predictions of Disease Mediated Changes in Drug Disposition in Patients with Nonalcoholic Fatty Liver Disease (NAFLD)

PURPOSE

This study was designed to verify a virtual population representing patients with nonalcoholic fatty liver disease (NAFLD) to support the implementation of a physiologically based pharmacokinetic (PBPK) modeling approach for prediction of disease-related changes in drug pharmacokinetics.

METHODS

A virtual NAFLD patient population was developed in GastroPlus (v.9.8.2) by accounting for pathophysiological changes associated with the disease and proteomics-informed alterations in the abundance of metabolizing enzymes and transporters pertinent to drug disposition. The NAFLD population model was verified using exemplar drugs where elimination is influenced predominantly by cytochrome P450 (CYP) enzymes (chlorzoxazone, caffeine, midazolam, pioglitazone) or by transporters (rosuvastatin, 11C-metformin, morphine and the glucuronide metabolite of morphine).

RESULTS

PBPK model predictions of plasma concentrations of all the selected drugs and hepatic radioactivity levels of 11C-metformin were consistent with the clinically-observed data. Importantly, the PBPK simulations using the virtual NAFLD population model provided reliable estimates of the extent of changes in key pharmacokinetic parameters for the exemplar drugs, with mean predicted ratios (NAFLD patients divided by healthy individuals) within 0.80- to 1.25-fold of the clinically-reported values, except for midazolam (prediction-fold difference of 0.72).

CONCLUSION

A virtual NAFLD population model within the PBPK framework was successfully developed with good predictive capability of estimating disease-related changes in drug pharmacokinetics. This supports the use of a PBPK modeling approach for prediction of the pharmacokinetics of new investigational or repurposed drugs in patients with NAFLD and may help inform dose adjustments for drugs commonly used to treat comorbidities in this patient population.

Drug targets regulate systemic metabolism and provide new horizons to treat nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH), is the advanced stage of nonalcoholic fatty liver disease (NAFLD) with rapidly rising global prevalence. It is featured with severe hepatocyte apoptosis, inflammation and hepatic lipogenesis. The drugs directly targeting the processes of steatosis, inflammation and fibrosis are currently under clinical investigation. Nevertheless, the long-term ineffectiveness and remarkable adverse effects are well documented, and new concepts are required to tackle with the root causes of NASH progression. We critically assess the recently validated drug targets that regulate the systemic metabolism to ameliorate NASH. Thermogenesis promoted by mitochondrial uncouplers restores systemic energy expenditure. Furthermore, regulation of mitochondrial proteases and proteins that are pivotal for intracellular metabolic homeostasis normalize mitochondrial function. Secreted proteins also improve systemic metabolism, and NASH is ameliorated by agonizing receptors of secreted proteins with small molecules. We analyze the drug design, the advantages and shortcomings of these novel drug candidates. Meanwhile, the structural modification of current NASH therapeutics significantly increased their selectivity, efficacy and safety. Furthermore, the arising CRISPR-Cas9 screen strategy on liver organoids has enabled the identification of new genes that mediate lipid metabolism, which may serve as promising drug targets. In summary, this article discusses the in-depth novel mechanisms and the multidisciplinary approaches, and they provide new horizons to treat NASH.

MASLD treatment-a shift in the paradigm is imminent

MASLD prevalence is growing towards the leading cause of end-stage liver disease. Up to today, the most effective treatment is weight loss. Weight loss interventions are moving from lifestyle changes to bariatric surgery or endoscopy, and, more recently, to a new wave of anti-obesity drugs that can compete with bariatric surgery. Liver-targeted therapy is a necessity for those patients who already present liver fibrosis. The field is moving fast, and in the near future, we will testify to a disruptive change in MASLD treatment, similar to the paradigm-shift that occurred for hepatitis C almost one decade ago with direct antiviral agents.

Hyperinsulinemia, an overlooked clue and potential way forward in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease is closely associated with other features of the metabolic syndrome such as type 2 diabetes. The progression of the disease may lead to liver fibrosis, which is the main predictor of major adverse liver outcomes. Insulin resistance plays a major role in the pathogenesis of the disease. A component of fasting hyperinsulinemia is a failure of the liver to adjust the peripheral level of insulin due to reduced clearance. The associated fasting hyperinsulinemia has been independently associated as a predictor of major adverse liver outcomes and major adverse cardiovascular events. In this review, we discuss the potential mechanism and entanglement between liver fibrosis and hyperinsulinemia, and we hypothesize that the measure of fasting insulin could become a hepatic functional test within the armamentarium of noninvasive tests for the assessment of Metabolic dysfunction-associated steatotic liver disease.

The emerging significance of mitochondrial targeted strategies in NAFLD treatment

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease worldwide, ranging from liver steatosis to nonalcoholic steatohepatitis, which ultimately progresses to fibrosis, cirrhosis, and hepatocellular carcinoma. Individuals with NAFLD have a higher risk of developing cardiovascular and extrahepatic cancers. Despite the great progress being made in understanding the pathogenesis and the introduction of new pharmacological targets for NAFLD, no drug or intervention has been accepted for its management. Recent evidence suggests that NAFLD may be a mitochondrial disease, as mitochondrial dysfunction is involved in the pathological processes that lead to NAFLD. In this review, we describe the recent advances in our understanding of the mechanisms associated with mitochondrial dysfunction in NAFLD progression. Moreover, we discuss recent advances in the efficacy of mitochondria-targeted compounds (e.g., Mito-Q, MitoVit-E, MitoTEMPO, SS-31, mitochondrial uncouplers, and mitochondrial pyruvate carrier inhibitors) for treating NAFLD. Furthermore, we present some medications currently being tested in clinical trials for NAFLD treatment, such as exercise, mesenchymal stem cells, bile acids and their analogs, and antidiabetic drugs, with a focus on their efficacy in improving mitochondrial function. Based on this evidence, further investigations into the development of mitochondria-based agents may provide new and promising alternatives for NAFLD management.

Current Therapeutical Approaches Targeting Lipid Metabolism in NAFLD

Nonalcoholic fatty liver disease (NAFLD, including nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH)) is a high-prevalence disorder, affecting about 1 billion people, which can evolve to more severe conditions like cirrhosis or hepatocellular carcinoma. NAFLD is often concomitant with conditions of the metabolic syndrome, such as central obesity and insulin-resistance, but a specific drug able to revert NAFL and prevent its evolution towards NASH is still lacking. With the liver being a key organ in metabolic processes, the potential therapeutic strategies are many, and range from directly targeting the lipid metabolism to the prevention of tissue inflammation. However, side effects have been reported for the drugs tested up to now. In this review, different approaches to the treatment of NAFLD are presented, including newer therapies and ongoing clinical trials. Particular focus is placed on the reverse cholesterol transport system and on the agonists for nuclear factors like PPAR and FXR, but also drugs initially developed for other conditions such as incretins and thyromimetics along with validated natural compounds that have anti-inflammatory potential. This work provides an overview of the different therapeutic strategies currently being tested for NAFLD, other than, or along with, the recommendation of weight loss.

Fifty years of the mitochondrial pyruvate carrier: New insights into its structure, function, and inhibition

The mitochondrial pyruvate carrier (MPC) resides in the mitochondrial inner membrane, where it links cytosolic and mitochondrial metabolism by transporting pyruvate produced in glycolysis into the mitochondrial matrix. Due to its central metabolic role, it has been proposed as a potential drug target for diabetes, non-alcoholic fatty liver disease, neurodegeneration, and cancers relying on mitochondrial metabolism. Little is known about the structure and mechanism of MPC, as the proteins involved were only identified a decade ago and technical difficulties concerning their purification and stability have hindered progress in functional and structural analyses. The functional unit of MPC is a hetero-dimer comprising two small homologous membrane proteins, MPC1/MPC2 in humans, with the alternative complex MPC1L/MPC2 forming in the testis, but MPC proteins are found throughout the tree of life. The predicted topology of each protomer consists of an amphipathic helix followed by three transmembrane helices. An increasing number of inhibitors are being identified, expanding MPC pharmacology and providing insights into the inhibitory mechanism. Here, we provide critical insights on the composition, structure, and function of the complex and we summarize the different classes of small molecule inhibitors and their potential in therapeutics.

Insulin sensitizers in 2023: lessons learned and new avenues for investigation

INTRODUCTION

'Insulin sensitizers' derived discoveries of the Takeda Company in 1970s. Pioglitazone remains the best in class with beneficial pleiotropic pharmacology, although use is limited by tolerability issues. Various attempts to expand out of this class assumed the primary molecular target was the transcription factor, PPARγ. Findings over the last 10 years have identified new targets of thiazolidinediones (TZDs) that should alter the drug discovery paradigm.

AREAS COVERED

We review structural classes of experimental insulin sensitizer drugs, some of which have attained limited approval in some markets. The TZD pioglitazone, originally approved in 1999 as a secondary treatment for type 2 diabetes, has demonstrated benefit in apparently diverse spectrums of disease from cardiovascular to neurological issues. New TZDs modulate a newly identified mitochondrial target (the mitochondrial pyruvate carrier) to reprogram metabolism and produce insulin sensitizing pharmacology devoid of tolerability issues.

EXPERT OPINION

Greater understanding of the mechanism of action of insulin sensitizing drugs can expand the rationale for the fields of treatment and potential for treatment combinations. This understanding can facilitate the registration and broader use of agents with that impact the pathophysiology that underlies chronic metabolic diseases as well as host responses to environmental insults including pathogens, insulin sensitizer, MPC, mitochondrial target, metabolic reprogramming, chronic and infectious disease.

Emerging targets for therapy in ALD: Lessons from NASH

Alcohol-associated liver disease due to harmful alcohol use and NAFLD associated with metabolic syndrome are the 2 most common liver diseases worldwide. Control of respective risk factors is the cornerstone in the long-term management of these diseases. Furthermore, there are no effective therapies. Both diseases are characterized by metabolic derangements; thus, the focus of this review was to broaden our understanding of metabolic targets investigated in NAFLD, and how these can be applied to alcohol-associated liver disease. Conserved pathogenic pathways such as dysregulated lipid metabolism, cell death pathways including apoptosis and activation of innate immune cells, and stellate cells mediate both alcohol and NAFLDs, resulting in histological abnormalities of steatosis, inflammation, fibrosis, and cirrhosis. However, pathways such as gut microbiome changes, glucose metabolism and insulin resistance, inflammatory signaling, and microRNA abnormalities are distinct in these 2 diseases. In this review article, we describe conserved and distinct pathogenic pathways highlighting therapeutic targets that may be of potential in both diseases and those that are unique to each disease.