Current and emerging pharmacological options for the treatment of nonalcoholic steatohepatitis

Stergios A. Polyzos, Eun Seok Kang, Chrysoula Boutari, Eun- Jung Rhee, Christos S. Mantzoros

Abbreviation list

ACC, acetyl-CoA carboxylase; ALT, alanine transaminase; APRI, AST-to-platelet ratio index; ASK, apoptosis signal-regulating kinase; ASP, aspartate transaminase; BMI, body mass index; CAP, controlled attenuation parameter; CCR, C-C chemokine receptor; CT, computerized tomography; CVD, cardiovascular disease; DPP, dipeptidyl peptidase; F, fibrosis stage; FFAs, free fatty acids; FGF, fibroblast growth factor; FIB-4, fibrosis-4; FXR, farnesoid X receptor; GGT, gamma glutamyl transferase; GLP-1 RA, glucagon-like peptide-1 receptor agonist; HbA1c, glycated hemoglobin; HCC, hepatocellular carcinoma; HDL-C, high-density lipoprotein-cholesterol; HVPG, hepatic venous pressure gradient; IR, insulin resistance; LDL-C, low-density lipoprotein-cholesterol; LFTs, liver function tests; LOLX, lysyl oxidase like; MAPK, mitogen-activated protein kinase; MetS, metabolic syndrome; MRA, mineralocorticoid receptor antagonist; MRE, magnetic resonance elastography; MRI, magnetic resonance imaging; MRI-PDFF, magnetic resonance imaging-derived proton density fat fraction; NAFLD, nonalcoholic fatty liver disease; NAS, NAFLD activity score; NASH, nonalcoholic steatohepatitis; OCA, obeticholic acid; PPAR, peroxisome proliferator activated receptor; RCT, randomized controlled trial; SGLT-2i, sodium-glucose cotransporter-2 inhibitors; SPPARMs, selective PPAR modulators; SS, simple steatosis; T2DM, type 2 diabetes mellitus; THR, thyroid hormone receptor; TNF, tumor necrosis factor; TZDs, thiazolidinediones; UDCA, ursodeoxycholic acid; VLDL-C, very low-density lipoprotein-cholesterol.


Nonalcoholic fatty liver disease (NAFLD) is a highly prevalent disease and important unmet medical need. Current guidelines recommend, under specific restrictions, pioglitazone or vitamin E in patients with NASH and significant fibrosis, but the use of both remains off- label. We summarize evidence on medications for the treatment of nonalcoholic steatohepatitis (NASH), since NASH has been mainly associated with higher morbidity and mortality. Some of these medications are currently in phase 3 clinical trials, including obeticholic acid (a farnesoid X receptor agonist), elafibranor (a peroxisome proliferator activated receptor [PPAR]-α/δ dual agonist), cenicriviroc (a C-C chemokine receptor antagonist), MSDC-0602K (a PPAR sparing modulator), selonsertib (an apoptosis signal- regulating kinase-1 inhibitor) and resmetirom (a thyroid hormone receptor agonist). A significant research effort is also targeting PPARs and selective PPAR modulators, including INT131 and pemafibrate, with the expectation that novel drugs may have beneficial effects similar to those of pioglitazone, but without the associated adverse effects. Whether these and other medications could offer tangible therapeutic benefits, alone or in combination, apparently on a background of lifestyle modification, i.e. exercise and a healthy dietary pattern e.g. Mediterranean diet remains to be proven. In conclusion, major advances are expected for the treatment of NASH. .

Keywords: farnesoid X receptor agonist; fibrosis; nonalcoholic fatty liver disease; nonalcoholic steatohepatitis; thiazolidinediones; treatment

1. Introduction

Nonalcoholic fatty liver disease (NAFLD) is a metabolic disorder, with a projected global prevalence of 25-30% in the general population, reaching 70-90% in specific populations, e.g. patients with type 2 diabetes mellitus (T2DM) and morbidly obese individuals, and a principal cause of chronic liver disease as well as cardiovascular morbidity and mortality [1]. NAFLD includes a variety of phenotypes, starting from simple steatosis (SS) that may progress to nonalcoholic steatohepatitis (NASH), which may subsequently advance to hepatic fibrosis, cirrhosis and hepatocellular carcinoma (HCC) [2]. Importantly, NASH has emerged as a leading cause of liver transplantation [3]. Mortality is higher in NASH patients, owing to hepatic (i.e., cirrhosis and HCC) and extra-hepatic morbidity, including cardiovascular diseases (CVD) and malignancies [4]. The pathogenesis of NAFLD is multifactorial: various more (e.g., genetic polymorphisms, diet, lack of physical activity, insulin resistance [IR]) or less (e.g., dysbiosis of gut microbiota, endocrine disruptors) well established factors interact with each other and contribute, to a different degree, to different patients over time (“multiple parallel-hit” hypothesis) [5,6]. Initially, the combination of certain inciting factors leads to intra-hepatic lipid accumulation, i.e. SS. The timely management of SS seems to be important in preventing further progression of the disease; otherwise immune cells infiltrate the liver, resulting in a low-grade inflammatory process, i.e. NASH [7]. If the disease fails to be managed at this stage, hepatic fibrosis may then appear in some patients, who may also progress to advanced disease (i.e. cirrhosis) [2].

Lipotoxicity and glucotoxicity, emanating from excess availability of lipids and carbohydrates, respectively, to hepatocytes, are of critical importance for the development of SS, but also for the possible progression to more advanced disease [7]. Pathophysiological mechanisms connecting lipotoxicity and glucotoxicity with SS and NASH include mitochondrial defects, endoplasmic reticulum stress and oxidative stress [5]. During the inflammatory process, the liver is gradually infiltrated by immune cells (mainly macrophages), but also the hepatic innate immune cells (Kupffer cells, dendritic cells and hepatic stellate cells) are also activated [8]. Within the liver, the immune cells release cytokines, thus exaggerating the inflammatory activity, but also contribute to the fibrotic process, when the inflammation persists [9]. During hepatic fibrogenesis, the immune cells interact with wound-healing cells, including activated myofibroblasts, endothelial cells and progenitor cells [5]. The multiple contributors and the complex underlying pathophysiology render the treatment of NAFLD a difficult task, given that different patients have different genetic predisposition and different lifelong exposure to different pathogenetic factors, which, in addition, may dynamically change over time. Therefore, although NAFLD is a highly prevalent disease, emerging as a global health epidemic with significant economic burden [10], there is currently no approved medication for its prevention and/or treatment; thus NAFLD remains a research topic of outmost importance [11,12].

Completed and ongoing clinical trials have mainly focused on the treatment of NASH, since this has been mainly associated with higher morbidity and mortality [4]. The endpoints in clinical trials have evolved over the past decade and are expected to continue to be further refined in the near future [13]. Currently accepted endpoints in clinical trials with NASH patients are the resolution of NASH without worsening of fibrosis and/or improvement in fibrosis without worsening of NASH, on the basis of standardized evaluation of liver histology following paired liver biopsies at baseline and at the end of clinical trials [13]. This is also expected to be the basis for on label use of any medications to be approved in the near future. It should be highlighted that the hepatic fibrosis is regarded as the main histological prognostic factor of advanced disease [14] and a difficult therapeutic target [15]. The primary endpoints in clinical trials with NASH-related cirrhosis are usually clinical events, including cirrhosis decompensation, HCC, transplantation and death [13]. One could argue that other, more frequent and equally important outcomes, such as cardiovascular morbidity as well as cardiovascular and overall mortality should be additional outcomes to be considered, but these have not yet been the focus of the FDA and other regulatory agencies, as they should. In addition, given the limitations in performing liver biopsies and/or the morbidity associated with those biopsies,
“liquid biopsy” blood tests with close to 100% correspondence with biopsies are urgently needed for clinical trials and future FDA approval of NASH medications [16].

The aim of this review is to summarize evidence on medications that have been investigated or are under investigation for the treatment of NASH. For the sake of coherence, the relevant medications have been conventionally grouped into “current” and “emerging” ones. The former include largely known medications, i.e. medications that having been approved for other diseases, relevant to NASH (e.g., T2DM, dyslipidemia) [17], whereas the latter include medications under investigation for NASH, which are generally not in the market. Medications having provided null or minimal effect on NASH are not extensively reviewed herein. Based on prevailing evidence, the effects of current and emerging medications on alanine transaminase (ALT), NAFLD activity score (NAS), hepatic steatosis, inflammation and fibrosis in patients with NASH are summarized in Table 1. Ongoing randomized controlled trials (RCTs) with histological and/or hard endpoints (cirrhosis decompensation, HCC, transplantation and death), regarding pharmacological options in patients with NASH are summarized in Table 2. The effect of medications on specific hepatic lesions (i.e., steatosis, inflammation and fibrosis), based on data of clinical trials for NASH, are schematically depicted in figure 1.

2. Lifestyle modifications

Lifestyle modifications (diet and physical activity), primarily aiming at gradual weight loss, are currently proposed by all guidelines as the first step of NAFLD management [18]. Owing to the lack of approved pharmacotherapy, lifestyle modification becomes even more important. It has been proposed that the resolution of NASH could be successful in 65- 90% of patients achieving ≥7% weight loss [19]. Likewise, the cut-offs of weight loss of ≥3%, ≥5% and ≥10% have been proposed to improve steatosis, inflammation and fibrosis, respectively [20]. These cut-offs in terms of body weight loss may refer to obese, but not lean patients with NAFLD (who are estimated to be about 7% of NAFLD patients [21]), in whom genetic predisposition may be stronger or body fat distribution different [22]. Thus, given the close association between visceral fat and NAFLD [23], the loss in visceral and ectopic fat, rather than the body weight, is more important, especially for lean NAFLD patients, but the specific cut-off points needed for histological improvement are difficult to estimate and remain currently unknown. Regarding the optimal type of diet and exercise, data remain inconclusive and largely limited by the lack of large, long-term studies with histological endpoints [5]. However, it seems that the main drive for NAFLD improvement is weight loss (or, even better, visceral fat loss), whereas the macro- or micro-nutrient composition of the diet [24,25] and the type of exercise [26] are of secondary importance [5] but this remains to be fully clarified. Therefore, the recommendation for individually-tailored diet and exercise programs, which may, thus, increase the likelihood of their long-term duration [27], seems rational at this point in time, pending more studies and more detailed studies. In general, a combination of aerobic and resistance training of 150-200 min/week has been proposed by most guidelines, as reviewed elsewhere [5]. Furthermore, the Mediterranean diet remains the only diet having resulted in additional beneficial metabolic and cardiovascular effects, at least in Europe. Thus, except for weight loss, the Mediterranean diet may be beneficial not only for NAFLD but also for other comorbidities closely linked to NAFLD, including T2DM, dyslipidemia and CVD [28]. Despite their beneficial effects, lifestyle modification is difficult to achieve and probably even more difficult to maintain in the long-term [29], which necessitates pharmacological management [15].

3. Current pharmacological options

3.1. Vitamin E

Vitamin E is a potent antioxidant that may reduce oxidative stress in NAFLD. Clinical trials with vitamin E administration in NASH patients provided promising results. A large RCT, the PIVENS (“Pioglitazone, Vitamin E or Placebo for Nonalcoholic Steatohepatitis”) trial showed that NASH patients treated with vitamin E (800 IU/day) were more likely than placebo to resolve NASH (43% and 19%, respectively), and improve hepatic steatosis and lobular inflammation, but not fibrosis [30]. A subsequent analysis reported that improvement in ALT was more common in the vitamin E group compared with the placebo group [31]. On the contrary, a meta-analysis that included five trials did not find any histological benefits with vitamin E [32]. Nevertheless, there was significant heterogeneity among the studies in this meta-analysis, concerning the vitamin E formula, the population, the duration of treatment and the recommended lifestyle modifications. It should be highlighted that high-dose vitamin E in the long-term has been linked with an increase in all-cause mortality in a dose-dependent manner [33], so its prolonged use (e.g., over two years, which was equal to the duration of PIVENS trial) should be avoided. Vitamin E has also been associated with higher risk of haemorrhagic stroke [33]. Additionally, due to a potentially increased risk of prostate cancer, vitamin E should be avoided in male patients with a personal or family history of prostate cancer [34]. Along these lines, vitamin E (800 IU/day) may be used for the treatment of NASH in selected patients, according to the guidelines of the European Association for the Study of the Liver (EASL) [27], the American Association for the Study of Liver Diseases (AASLD) [35] and the Korean Association for the Study of the Liver (KASL) [36].

3.2. Thiazolidinediones

Thiazolidinediones (TZDs: pioglitazone and rosiglitazone), which are peroxisome proliferator activated receptor (PPAR)-γ ligands, are approved medications for T2DM, usually as second-line options [37]. Owing to the upregulation of adiponectin, TZDs have been used in several trials for NASH [38]. IR and LFTs were improved after TZDs [38]. Regarding histology, systematic reviews and meta-analyses showed that steatosis, lobular inflammation and ballooning, the hallmark of hepatic inflammation, were improved after TZDs [38-41]. However, this was observed after pioglitazone, but not after rosiglitazone treatment [38]. Fibrosis was marginally improved in two meta-analyses [40,41], whereas it was, again marginally, not altered in another [39]. It is highlighted that no single study of those included in the above mentioned meta-analyses showed improvement in fibrosis [39- 41], possibly owing to small samples sizes and/or short duration of treatment [38]. On the contrary, longer duration of treatment (18 months) with pioglitazone showed an improvement in mean fibrosis stage, but not in the rates of patients with improvement compared with placebo [42]. Furthermore, TZDs discontinuation led to worsening of IR, LFTs and hepatic histology [43]. The last observations may possibly imply that long-term treatment with TZDs is required to improve fibrosis and maintain the improvement achieved in histology; however, more data on the long-term efficacy and safety of TZDs in NASH are required.
Weight gain (on average 2.0-3.5 kg) is an adverse effect of TZDs treatment, which is important given that most NASH patients are obese; however, TZDs result in fat redistribution mainly from visceral to subcutaneous adipose tissue, thus exerting beneficial effects on metabolism [38]. Another major consideration is an adverse effect of rosiglitazone, but not pioglitazone, on lipid profile, leading to the restriction of rosiglitazone use owing to a slight increase in myocardial infarction risk [44].

Pioglitazone use has been also linked to a possibly slight increase in bladder cancer risk after long-term use in T2DM patients [45]. Such bladder cancer risk remains controversial, since other authors did not observe an association between pioglitazone use and bladder cancer risk and the authors of a recent meta- analysis concluded that the beneficial effects of pioglitazone on NASH and CVD are much greater than the possible slight increase in bladder cancer risk [46,47]. However, based on these findings, pioglitazone has been suspended in some European countries and India; FDA made a “black box statement” that pioglitazone may be linked to increased risk of bladder cancer and a warning against pioglitazone use by patients with bladder cancer [45]. There are also observations on an association between ever use of pioglitazone and higher risk of prostate and pancreatic cancer that remain to be fully confirmed or refuted [47], since other authors observed lower risk of prostate cancer in pioglitazone users [48]. In addition, pioglitazone use has been proposed to be useful against pancreatic cancer, since the activation of PPAR-γ inhibits nuclear factor-κB pathway, thus inhibiting cell proliferation, apoptosis resistance and synthesis of inflammatory cytokines in cancer cells [49]. Thus, findings of observational studies on the association of pioglitazone and prostate or pancreatic cancer risk needs further investigation to exclude the effect of residual confounding or reverse causality [47]. More safety data are also required for TZDs on bone metabolism [38]; until definite conclusions are available, pioglitazone should be avoided in NASH patients with high risk of fractures. Thus, under strictly personalized criteria, pioglitazone may be used for the treatment of NASH in selected diabetic patients, according to the guidelines of the EASL [27], the AASLD [35] and the KASL [36]. Of course, pioglitazone should not be administered in patients with bladder cancer, and should be currently avoided in those with prostate or pancreatic cancer and/or in nondiabetic subjects. Furthermore, patients with long- term exposure to pioglitazone may be regularly monitored for signs of bladder cancer (e.g. hematuria) [45].

3.3. Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors

GLP-1 RAs have many biological effects that make them a promising candidate treatment option for NASH. They reduce glucagon secretion from pancreatic α-cells, increase insulin secretion in a glucose-dependent manner, suppress hepatic de novo lipogenesis, increase fatty acid oxidation, delay gastric emptying, and suppress appetite [50,51]. Several GLP-1 RAs have been developed and used for T2DM and obesity. However, none of them has been approved for the treatment of NASH due to limited data. The LEAN study (“Liraglutide Efficacy and Action in Non-alcoholic steatohepatitis”) is a phase 2 clinical trial that examines the effects of liraglutide on NASH [52]. Fifty-two patients with biopsy- confirmed NASH were randomized to receive either 1.8 mg/day of liraglutide subcutaneously or placebo for 48 weeks. Improvement of steatosis was more common on liraglutide than placebo (83% vs. 45%, respectively), and worsening of fibrosis was less frequent on liraglutide (9% vs. 36%, respectively); however, liraglutide did not improve fibrosis in higher rates than placebo. Resolution of NASH without worsening of fibrosis was observed in 39% of liraglutide group and 9% of placebo group; however, the mean change in NAS was similar
between groups [52]. Notably, there was greater weight loss in patients on liraglutide than those on placebo (−5.5 vs. −0.6 kg, respectively).

The “Liraglutide Effect and Action in Diabetes” (LEAD)-2 sub-study showed that liraglutide had a tendency towards improving hepatic steatosis vs. placebo on liver-to-spleen attenuation ratio on computerized tomography (CT) [53]. In LEAN-J study, 19 Japanese patients with biopsy-confirmed NASH and high ALT level received liraglutide 0.9 mg/day for 24 weeks [54]. Liraglutide treatment significantly improved BMI, visceral fat, LFTs and glucose tolerance. The Lira-NAFLD trial (“Effect of Liraglutide Therapy on Liver Fat Content in Patients With Inadequately Controlled Type 2 Diabetes”) [55] showed that 6 months of treatment using 1.2 mg of liraglutide in 68 patients with uncontrolled T2DM was associated with a 31% reduction in liver fat content, as measured by magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF). However, instead of phase 3 trial with liraglutide in NASH, the same pharmaceutical company initiated a phase 2b trial (NCT02970942) investigating the efficacy and safety of semaglutide for 72 weeks of treatment in 372 patients with NASH. The trial is scheduled to be finished in July 2020. There have been some studies using exenatide [56,57] or dulaglutide [58] that showed modest improvement in NAFLD. No RCTs on lixisenatide for NAFLD have been reported. For now, further studies are needed to confirm whether the effects of GLP-1 RAs on NAFLD are “class effects”. Although DPP-4 inhibitors are widely used to treat T2DM, results from many studies showed no beneficial effects on NAFLD. Sitagliptin decreased aspartate transaminase (AST), ALT, and gamma glutamyl transferase (GGT) in patients with NAFLD and T2DM [59]. In a 1-year RCT, sitagliptin decreased hepatocellular ballooning and NAS, but not steatosis, lobular inflammation and fibrosis, more than placebo [60]. One study investigated the effect of vildagliptin on hepatic triglyceride levels in 44 patients with T2DM [61]. Vildagliptin was shown to decrease hepatic triglyceride levels and ALT during 6 months of therapy. On the contrary, other studies in patients with NAFLD demonstrated that sitagliptin had no beneficial effect on liver enzymes [62,63], liver steatosis [64,65] or liver stiffness [63].

3.4. Sodium glucose cotransporter-2 inhibitors (SGLT-2i)

SGLT-2i decrease blood glucose by inhibiting renal glucose reabsorption, thereby inducing glycosuria, which in turn promotes weight loss. The outcomes of several cardiovascular trials on SGLT-2i showed attenuating kidney disease progression and cardiovascular events in patients with T2DM [66-68]. E-LIFT trial (“Effect of Empagliflozin on Liver Fat in Patients With Type 2 Diabetes and Nonalcoholic Fatty Liver Disease”) investigated the effect of empagliflozin on liver fat using MRI-PDFF [69]. Fifty patients with T2DM and NAFLD were randomly assigned to either empagliflozin or placebo for 20 weeks. Empagliflozin significantly reduced liver fat (from 16% to 11%) and serum ALT. Shimizu et al. [70] evaluated the effects of 24 weeks dapagliflozin on hepatic steatosis and fibrosis using transient elastography in 57 patients with T2DM and NAFLD. The dapagliflozin group demonstrated a significant decrease in steatosis, as evaluated by controlled attenuation parameter (CAP) score. A randomized 6-month trial in 55 Japanese patients with T2DM showed that dapagliflozin treatment reduced liver fat, as evaluated by liver-to-spleen ratio on CT [71]. In another study, 11 Japanese patients with biopsy-confirmed NASH and T2DM were treated with dapagliflozin for 24 weeks [72]. Dapagliflozin treatment showed improvement in serum ALT and AST and reduction in visceral fat. One study evaluated the effect of 12-month treatment with canagliflozin on hepatic fat fraction with MRI-PDFF in 20 subjects with NAFLD and T2DM. Liver fat fraction decreased from 18% to 12% after canagliflozin treatment [73]. Moreover, canagliflozin for 12 weeks in 10 patients with T2DM and NASH improved ALT, AST, and fibrosis-4 (FIB-4), a non-invasive index of fibrosis [74]. Another study showed that a 24-week treatment with canagliflozin decreased intrahepatic triglyceride, as measured by MRI-PDFF, as compared to placebo [75]. Similarly, ipragliflozin treatment reduced liver stiffness, as measured by Fibroscan, in 43 patients with NAFLD and T2DM [76]. In a 24-week, head-to-head comparative study (ipragliflozin vs. pioglitazone) [77] in 66 patients with T2DM and NAFLD both groups hepatic steatosis, assessed by liver-to-spleen ratio on CT, was improved in both groups. Notably, the FIB-4 index decreased in ipragliflozin, but not pioglitazone group. As expected, unlike pioglitazone, ipragliflozin induced weight loss. Last but not least, the combination of dapagliflozin and exenatide (a GLP-1 RA) reduced non-invasive indices of steatosis (fatty liver index) and fibrosis (FIB-4) more effectively than each monotherapy in patients with T2DM, as shown in a post-hoc analysis of DURATION-8 (“Phase 3 28-Week Study With 24-Week and 52-week Extension Phases to Evaluate Efficacy and Safety of Exenatide Once Weekly and Dapagliflozin Versus Exenatide and Dapagliflozin Matching Placebo” [78]. However, although appealing, more safety data and data with histological endpoints are needed for the combinations of GLP-1 RA and SGLT-2i.

3.5. Statins

Patients with NASH are at increased cardiovascular risk [79]. Thus, the treatment of dyslipidemia is of high importance. Statins are well established in the treatment of dyslipidemia and the prevention of cardiovascular events. Despite the notion of their harmful effect in patients with elevated LFTs in the past [80], their use in NAFLD patients was shown to reduce the mean LFTs and improve cardiovascular mortality more in patients than mild-to- moderately abnormal LFTs than in those with normal LFTs in the GREACE (“Greek Atorvastatin and Coronary Heart Disease Evaluation”) study [81]. These findings were subsequently validated by the post-hoc analysis of the IDEAL (“Incremental Decrease in End Points Through Aggressive Lipid Lowering”) trial [82], which compared the effects of atorvastatin or simvastatin in a large Scandinavian population with established cardiovascular disease. In the IDEAL trial, atorvastatin normalized LFTs in patients with initially elevated LFTs and resulted in a greater reduction in the risk of major cardiovascular events, compared to simvastatin. Likewise, the sub-analysis of the ATTEMPT (“Assessing the treatment effect in metabolic syndrome without perceptible diabetes”) study [83] showed that atorvastatin normalized the LFTs and improved ultrasonographic findings in patients with metabolic syndrome. All the above considering, the use of statins in NASH patients must not be avoided, at least for the protection of cardiovascular events, which is the primary cause of mortality in NASH patients [84].

Nonetheless, studies with histological endpoints have provided conflicting results: some studies showed a beneficial effect of statins on hepatic histology [85-87], whereas others provided null effects [88,89]. In a meta-analysis, statins were shown to decrease LFTs and hepatic steatosis, but have no effect on fibrosis [90]. Regarding hepatic inflammation, some, but not all studies, reported its improvement [90]. A given limitation of existing RCTs of statins in NASH patients, beyond the fact they have not been specifically designed for NASH, is their duration, which may be too short for a hard endpoint like fibrosis to improve. Thus, longer-term studies with statins in NASH are warranted to clarify whether the initial improvement in hepatic steatosis, observed relatively soon after their administration, is translated in an improvement in fibrosis later, if statin use is prolonged [91]. In a US nationwide study with chronic viral hepatitis, lipophilic statin use (atorvastatin, simvastatin, lovastatin and fluvastatin) was associated with reduced risk of 10- year incident HCC and all-cause mortality. Although hydrophilic statin use (rosuvastatin and pravastatin) also reduced all-cause mortality, they did not reduce the 10-year risk of HCC [92]. This study warrants similar studies in large NAFLD populations to investigate whether statin use is translated in reduced all-cause mortality in NAFLD too and whether the lipophilic statins have an advantage over the hydrophilic ones in terms of HCC.

3.6. Omega-3 polyunsaturated fatty acids

Omega-3 polyunsaturated fatty acids are frequently administered to treat hypertriglyceridemia and have been investigated in patients with NAFLD to improve liver disease. A meta-analysis initially showed that omega-3 may be effective in improving LFTs and hepatic steatosis [93]. However, the subsequent EPE-A (“Ethyl-eicosapentanoic acid”) study [94] and WELCOME (“Wessex Evaluation of fatty Liver and Cardiovascular markers in NAFLD with OMacor therapy”) study [95], performed to evaluate the effects of omega-3 fatty acids in patients with NASH (ethyl-eicosapentanoic acid) and NAFLD (eicosapentanoic acid plus docosahexaenoic acid), respectively, did not provide favorable results. EPA-E failed to show any improvement in hepatic histology [94], and, likewise, the primary analysis of the WELCOME did not show improvement in liver fat or non-invasive indices of fibrosis [95]. Based on these results, omega-3 fatty acids are not currently recommended for the treatment of NASH [35].

3.7. Orlistat

Orlistat is an anti-obesity medication, approved since 1998 and 1999 in the USA and Europe, respectively. It is a saturated derivative of lipostatin acting by inhibiting gut and pancreatic lipases, and prevents the absorption of dietary triglycerides, thereby promoting weight loss. In a 6-month RCT in patients with ultrasound-diagnosed NAFLD, orlistat treatment showed a 2-fold reduction in serum ALT and improved steatosis [96]. In a 6-month uncontrolled study with obese NASH patients subjected to paired liver biopsies (n = 14), orlistat reduced ALT and steatosis in 10, inflammation in 11 and fibrosis in 10 of these patients [97]. These rates of improvement have been considered as higher than expected. In another uncontrolled study with obese NASH patients with paired liver biopsies (n = 10) on orlistat, steatosis was reduced in six, inflammation in two and fibrosis in one (whereas fibrosis worsened in another one) [98]. In this study, a 10% weight loss was needed to improve fibrosis [98]. In 9-month comparative RCT (vitamin E monotherapy with the combination of vitamin E and orlistat), orlistat failed to show an additive effect on NAFLD [99]. When the patients were stratified according to weight loss instead of treatment group, steatosis was improved after a 5% weight loss and hepatic inflammation after a 9% weight loss, as expected [99]. This study implies that the improvement in hepatic histology is driven by weight loss and not orlistat itself [5]. In a recent meta-analysis analyzing three RCTs and four single-arm trials, orlistat was shown to improve BMI, LFTs and insulin resistance, but not hepatic fibrosis [100]. These results indicate that orlistat could be considered for the improvement of hepatic steatosis and possibly inflammation, but this effect is observed only in those who achieve significant weight loss.

3.8. Ursodeoxycholic acid

Abnormal lipid metabolism and dysregulation of pro-inflammatory factors contribute to the progression of NASH [101]. Consequently, the exogenous administration of a non- toxic bile acid, such as ursodeoxycholic acid (UDCA) may act cytoprotectively. Animal studies attributed insulin-sensitizing, anti-inflammatory (reduction in pro-inflammatory cytokines) and anti-apoptotic properties to UDCA; UCDA may also be protective against mitochondrial lesions [102-104]. A systematic review of 12 RCTs [105] reported that UDCA is effective in NASH, especially when combined with other drugs, anti-oxidants to the most, such as vitamin E, vitamin C, polyene phosphatidylcholine, silymarin, glycyrrhizin or tiopronin. However, most of the included studies were of low quality and the meta-analysis showed high heterogeneity. Thus, there is currently limited evidence to support the widespread use of UDCA in NASH patients. However, since it is not associated with considerable adverse effects over prolonged periods, it has been proposed that UDCA can reach the dose of 13-15 mg/kg/day and should be discontinued if the goal of LFTs normalization is not reached within 3-6 months [101].

3.9. Mineralocorticoid receptor antagonists

Spironolactone, a mineralocorticoid receptor antagonist (MRA), was shown to improve IR, hepatic steatosis and suppress lipogenic and inflammatory genes in the liver of a mouse model with T2DM and NAFLD [106]. Low-dose spironolactone (25 mg/d) in combination with vitamin E decreased IR more than vitamin E monotherapy after a 2-month treatment in NAFLD patients [107]. After a 1-year treatment, the combination of spironolactone and vitamin E decreased NAFLD liver fat score, a noninvasive index of hepatic steatosis, more the vitamin E monotherapy [108]. Adverse effects were similar between groups without any serious ones [108]. This possible effect of spironolactone was not shown to be mediated by noggin [109] or asporin [110] in post-hoc analyses. Although this study did not show an effect of spironolactone on AST-to-platelet ratio index (APRI), an noninvasive index of hepatic fibrosis, further studies with paired liver biopsies in NASH patients with advanced fibrosis are warranted to elucidate whether spironolactone, an inexpensive medication, may provide benefit in hepatic fibrosis. In this regard, a placebo controlled RCT with spironolactone (100 mg/d) in women with NASH is ongoing with primary endpoint the liver stiffness, assessed by magnetic resonance elastography (NCT03576755).

4. Emerging pharmacological options

4.1. Farnesoid X receptor (FXR) agonists

FXR is a member of the nuclear receptor superfamily controlling a variety of genes involved in bile acid synthesis and transport, but also in glucose and lipid metabolism [111]. Obeticholic acid (OCA), an FXR agonist approved for the treatment of primary biliary cholangitis, has provided encouraging results in patients with NASH and fibrosis [112-115]. In a phase 2 RCT, a 6-week OCA treatment improved IR and LFTs more than placebo in patients with NAFLD and T2DM [112]. Notably, OCA 25 mg was more effective than 50 mg. Next, a phase 2b RCT, named “The Farnesoid X Receptor Ligand Obeticholic Acid in NASH Treatment” (FLINT), showed that a 72-week treatment with OCA 25 mg (vs. placebo) improved hepatic histology in NASH patients without cirrhosis [113]. More specifically, hepatic steatosis (61% vs. 38%), lobular inflammation (53% vs. 35%), hepatocellular ballooning (46% vs. 31%) and, importantly, fibrosis (35% vs. 19%) decreased more in the OCA than the placebo group, respectively [113]. Likewise, an 18-month interim analysis of an ongoing RCT in NASH patients without cirrhosis, named “The Randomized Global Phase 3 Study to Evaluate the Impact on NASH With Fibrosis of Obeticholic Acid Treatment” (REGENERATE), showed higher rates of fibrosis improvement (without worsening of NASH) in OCA 25 mg and 10 mg vs. placebo (23% vs. 18% vs. 12%, respectively) [115]. Nevertheless, adverse effects were observed in OCA groups, the most common being pruritus (51% and 28% in OCA 25 mg and 10 mg groups, respectively, in the interim analysis of REGENERATE [115]) and unfavorable changes in the lipid profile (increase in low-density
lipoprotein-cholesterol [LDL-C] and decrease in high-density lipoprotein-cholesterol [HDL- C]) [113,115], leading to discontinuation of treatment in some patients. A post-hoc analysis of FLINT trial showed that OCA specifically increases small very low-density lipoprotein- cholesterol (VLDL-C) particles, large and small LDL-C particles, and decreases HDL-C particles at 12 weeks [116]. For this reason, another RCT, named “Clinical Study Investigating the Effects of Obeticholic Acid and Atorvastatin Treatment on Lipoprotein Metabolism in Subjects With Nonalcoholic Steatohepatitis” (CONTROL), showed that the co-administration of atorvastatin 10 mg with OCA may mitigate the unfavorable effect of OCA on LDL-C, but not on HDL-C [114].

Except for OCA, other FXR agonists are currently investigated for the treatment of NASH. For example, preliminary data on a 12-week cilofexor (GS-9674) treatment, in combination with firsocostat (an acetyl-CoA carboxylase [ACC] inhibitor), improved LFTs, hepatic steatosis, liver stiffness and serum fibrosis markers, without causing pruritus [117]. Tropifexor also provided favorable results in rodents with NASH [118]. Ongoing RCTs evaluating FXR agonists, including cilofexor and tropifexor are summarized in Table 2. Nidufexor (LMB763) is a recently introduced FXR agonist, designed to mitigate the adverse lipid effects observed with OCA. Nidufexor provided favorable results on hepatic histology in murine NASH models and was well tolerated in a phase 1 study, thus phase 2 studies in NASH patients are expected [119]. In conclusion, FXR agonists seem to be promising for the treatment of NASH, given their effectiveness in improving hepatic fibrosis; however, improvement of their safety profile is needed, since NASH patients have commonly dyslipidemia and are on high CVD risk [120].

4.2. PPARs and selective PPAR-γ modulators

Based on the above mentioned adverse effects and the safety considerations of TZDs, selective PPAR-γ or other PPARs modulators are under evaluation in NASH patients, aiming to limit the adverse effects of TZDs. Elafibranor (GFT505) is PPAR-α/δ dual agonist. Following favorable results in rodents [121], a 8-week treatment with elafibranor (80 mg/d) reduced LFTs, triglycerides, LDL-C and hepatic IR in obese individuals [122]. Of note, target genes were not induced in the skeletal muscle, thus elafibranor possibly showing a hepatic selectivity [122]. Contrary to PPAR-γ agonists, elafibranor reduced adiponectin levels [122], which however, may implicate NASH treatment, since adiponectin seems to be possibly associated with the disease severity [123]. In a subsequent phase 2, 1-year RCT (GOLDEN-505), elafibranor 120 mg/d, but not 80 mg/d, met the primary outcome, being reversal of NASH without worsening of fibrosis, for patients with NASH ≥4, but not those with <4 [124]. Hepatic steatosis, inflammation and fibrosis were not significantly improved with elafibranor, showing a trend towards improvement in patients with more severe disease [124]. Both 80 and 120 mg/d of elafibranor improved LFTs and lipid profile, and HOMA-IR in T2DM patients. Body weight remained essentially unchanged, contrary to PPAR-γ full agonists [124]. Elafibranor was well tolerated and no major adverse events were recorded. A reportedly mild and reversible increase in creatinine, however, needs further evaluation [124]. Elafibranor is currently investigated vs. placebo in a phase 3 RCT (NCT02704403; Table 2). Saroglitazar is a PPAR-α/γ dual agonist. It reduced LFTs, hepatic steatosis, inflammation and possibly fibrosis in mice with NASH [125]. It also reduced NAS more than pioglitazone (PPAR-γ agonist) or fenofibrate (PPAR-α agonist) [125]. In patients with diabetic dyslipidemia, saroglitazar had beneficial effect on lipid profile, glycated hemoglobin (HbA1c), ALT and liver imaging, without affecting body weight and without major adverse events [126]. Based on these considerations, there are two ongoing RCTs with saroglitazar and histological endpoints, as presented in Table 2. Lanifibranor (IVA337) is a pan-PPAR agonist (PPAR-α/γ/δ) designed as anti-fibrotic agent [127]. In mice with NASH, lanifibranor improved hepatic steatosis, inflammation and fibrosis. Notably, lanifibranor increased adiponectin as pioglitazone and decreased triglycerides as fenofibrate, possibly combining the beneficial effects of PPAR-γ and PPAR-α [128]. A phase 2 RCT with lanifibranor in NASH patients is ongoing (NCT03008070; Table 2). MSDC-0602K is a second generation TZD, designed to selectively modulate the mitochondrial pyruvate carrier, as the first generation TZDs (pioglitazone, rosiglitazone); however, its PPAR-γ activity is reportedly limited (PPAR-γ sparing modulator), which is expected to reduce the adverse effects observed with the first generation TZDs [129]. EMMINENCE (“A Study to Evaluate the Safety, Tolerability & Efficacy of MSDC 0602K in Patients With NASH”) is a 1-year, phase 2 RCT with MSDC-0602K in NASH. In an interim (6-month) analysis, MSDC-0602K showed favorable effects on LFTs and noninvasive indices of fibrosis [129]. In the final analysis, MSDC-0602K, at the dose of 125 and 250 mg, improved glucose, IR, LFTs and NAS compared with placebo, but failed to meet the primary endpoint of the study, being the improvement of at least two points in NAS with a ≥1-point reduction in either ballooning or lobular inflammation and no increase in fibrosis stage [130]. Steatosis was decreased only in the high MSDC-0602K dose compared with placebo, whereas MSDC-0602K did not reduced inflammation and fibrosis [130]. As expected, safety limitations observed with the first generation PPAR-γ (TZDs) were not evident with MSDC- 0602K. INT131 (formerly AMG131) is a non-TZD, selective PPAR-γ modulator (SPPARM)- γ, designed to exhibit a strong efficacy, but minimal side effects compared to PPAR-γ full agonists. INT131 increases adiponectin in a dose- and a time-response fashion [131-133]. INT131 decreased HbA1c in a dose-dependent fashion and was well tolerated in phase 2 RCTs on T2DM patients [132,133]. Notably, less adverse events were recorded compared to rosiglitazone [132] or pioglitazone [133], including weight gain and fluid retention. In this regard, trials with INT131 in NASH patients are warranted, and are expected to demonstrate beneficial effects on hepatic histology without the adverse events of rosiglitazone or pioglitazone [38]. Pemafibrate (K-877) is a novel SPPARM-α having provided favorable results in rodents with NASH [134]. In patients with dyslipidemia, a 6-month pemafibrate treatment reduced triglyceride levels more than fenofibrate (full PPAR-α agonist) [135]. Importantly, pemafibrate decreased ALT and GGT, whereas fenofibrate increased both [135]. Pemafibrate was generally well tolerated in this study [135]. Based on these findings an RCT with pemafibrate in NAFLD patients (without histological endpoints) is ongoing (NCT03350165). 4.3. C-C chemokine receptor (CCR)2/5 antagonists Cenicriviroc is a dual CCR2/CCR5 inhibitor, and it shows anti-inflammatory and anti-fibrotic effects on animals [136,137]. Cenicriviroc is being evaluated in clinical trials with NASH patients. CENTAUR (“Cenicriviroc for the Treatment of NASH in Adult Participants With Liver Fibrosis”; NCT02217475), a 2-year, phase 2b study of cenicriviroc (150 mg daily) in 289 patients with F1-F3 fibrosis, is currently ongoing [138]. In the 1-year interim analysis, cenicriviroc did not meet the primary endpoint, being an at least 2-point improvement in NASH without worsening of fibrosis. However, cenicriviroc met the endpoint in a subset of patients with more severe NASH (defined as NAS ≥5) [138]. Importantly, more patients on cenicriviroc (20%) than on placebo (10%) met the secondary endpoint, being improvement in fibrosis, by at least one stage without worsening of NAS. Hepatocellular ballooning was improved only in a subset of patients with prominent baseline ballooning (grade 2). LFTs and hepatic steatosis were not improved by cenicriviroc [138]. Over the 2-year treatment period, a similar proportion of patients receiving CVC or placebo achieved ≥1-stage fibrosis improvement without worsening of NASH [139]. However, the effect on fibrosis achieved at year 1 was maintained at year 2 in higher rates in CVC group, particularly in the subset of patients with advanced fibrosis. Most specifically, 60% of patients on CVC achieved ≥1-stage fibrosis improvement at the end of year 1 and maintained this response at year 2 as compared to the 30% of those on placebo [139]. CVC was well tolerated, with a similar safety profile as placebo [139]. Based on these results, a phase 3 trial of cenicriviroc in NASH is ongoing (NCT03028740) [140]. 4.4. Apoptosis signal-regulating kinase 1 (ASK1) inhibitors ASK1 is a mitogen-activated protein kinase (MAPK)3 that, upon activation by extracellular tumor necrosis factors (TNF)-α, intracellular oxidative or endoplasmic reticulum stress, activates p38/Janus kinase (JNK) pathway, resulting in hepatocyte apoptosis and fibrosis [141]. Selonsertib (GS-4997), an oral ASK1 inhibitor, when given to animals with NASH, showed a significant improvement in hepatic steatosis, fibrosis, IR and fasting blood glucose levels [142]. In a phase 2 RCT evaluating the effects of selonsertib, alone or in combination with simtuzumab, in NASH patient with hepatic fibrosis, patients receiving selonsertib demonstrated improvement in hepatic fibrosis, liver stiffness and liver fat content; furthermore progression to cirrhosis was observed in lower rates in patients on selonsertib [143]. There was no additive effect of simtuzumab on selonsertib. A given limitation of this study is the lack of placebo group, even if the effect of simtuzumab on NASH is minimal, as mentioned above. Based on these findings, phase 3 trials evaluating selonsertib among patients with NASH (STELLAR3; NCT03053050) or NASH-related cirrhosis (STELLAR4; NCT03053063) are ongoing (Table 2). 4.5. Fibroblast growth factor 21 (FGF21) analogues FGF21 is produced in the liver, where it reduces hepatic lipogenesis and enhances fatty acid oxidation [144]. FGF21 improves glucose metabolism by enhancing insulin sensitivity via promoting glucose uptake in the skeletal muscle and brown adipose tissue [145]. FGF21 is also reported to have anti-fibrotic effects in the liver. Several FGF21 mimetics have been developed in recent years. LY2405319 is the first FGF21-based drug studied in patients with obesity and T2DM. Daily injections of LY2405319 for 28 days resulted in improvement of lipid profile as well as in reduction of body weight and fasting insulin levels [146]. In obese people with T2DM, PF-05231023 significantly reduced body weight and improved lipid profile [147]. Pegbelfermin (BMS-986036; a PEGylated human recombinant FGF21 analogue) has been studied in patients with NASH in a phase 2a RCT (NCT02413372) [148]. In this study, 75 patients with biopsy-proven NASH and hepatic fat fraction ≥10%, as assessed by MRI-PDFF, were randomly assigned to receive subcutaneous injection of 10 mg daily, 20 mg weekly, or placebo daily for 16 weeks. At the end of the study, hepatic fat fraction was decreased in both active arms compared to the placebo arm. It improved Pro-C3, a fibrosis biomarker [149], as well as liver stiffness and LFTs. However, this study did not evaluate the effects of pegbelfermin on liver histology. An international phase 3 clinical study of pegbelfermin for the treatment of NASH with fibrosis stage 3/4 is set to be performed in the near future. 4.6. ACC inhibitors The rate-limiting step in de novo lipogenesis is the conversion of acetyl-CoA to malonyl-CoA, which is medicated by the enzyme ACC. Therefore, it has been thought that ACC inhibition could attenuate hepatic steatosis. In a pilot open-label, prospective study, 10 patients with possible NASH, as diagnosed with MRI-PDFF and magnetic resonance elastography (MRE), received firsocostat (GS-0976; an ACC inhibitor) for 12 weeks (NCT02856555) [150]. Hepatic de novo lipogenesis was reduced by 22% with firsocostat treatment. Hepatic steatosis, estimated by MRI-PDFF, was reduced by 43%, and hepatic stiffness, measured by MRE, decreased by 9% at 12 weeks. Adiponectin was decreased following firsocostat treatment, but LFTs and lipid profile did not significantly change [150]. In a subsequent phase 2 clinical RCT, 126 patients with possible NASH and estimated F1–F3 fibrosis were assigned to receive either firsocostat or placebo for 12 weeks [151]. Firsocostat showed >30% decrease in steatosis in 23% and 48% of patients (on 5 mg/day and 20 mg/day, respectively) compared to 15% in the placebo group, as assessed by MRI-PDFF. However, it did not change LFTs and liver stiffness, assessed by MRE. Serum tissue inhibitor of metalloproteinase 1was decreased with firsocostat, but not procollagen III N-terminal peptide or hyaluronic acid, all used as fibrosis markers [151]. A 13% increase in serum levels of triglycerides was observed in patients who were treated with firsocostat. The elevation in serum triglycerides is believed to be due to the increase in VLDL-C synthesis and decrease in lipoprotein lipase activity [152,153]. Firsocostat is currently evaluated, alone or in combination with an FXR analogue and an ASK1 inhibitor, in NASH (NCT03449446; Table 2).

4.7 Lysyl oxidase like (LOXL) inhibitors

Lysyl oxidase and LOXL are a family of enzymes expressed and secreted by fibrogenic cells and catalyze oxidative deamination of lysyl and hydroxylysine residues in collagen precursors and elastin, resulting in covalent cross-linking of the extracellular matrix, which is believed to contribute to the dissolution of hepatic scarring [154,155]. LOXL2 is upregulated in hepatocytes and its expression is correlated with collagen deposition in various hepatic fibrotic diseases [156]. Simtuzumab is a monoclonal antibody against LOXL2 that can be administered intravenously or subcutaneously. Despite initial expectations, i.e, simtuzumab acting as an anti-fibrotic agent, in two phase 2b trials performed in NASH patients with bridging fibrosis or compensated cirrhosis, respectively, simtuzumab was ineffective in decreasing hepatic collagen content or hepatic venous pressure gradient, respectively [157]. In conclusion, simtuzumab was withdrawn as a candidate for NASH treatment. Other LOXL inhibitors may prove to be more effective to reduce hepatic fibrosis in the future.

4.8. Gallectin-3 inhibitors

Modulating cellular responses against inflammation or fibrosis seems to be promising for NASH treatment [158]. Galectin-3 plays a key role in the development of hepatic fibrosis and is increased in NASH; its highest levels are observed in macrophages surrounding lipid- laden hepatocytes. Galectin-3 inhibition in animal models resulted in improvement of hepatic fibrosis [159]. In a phase 2a trial in NASH patients with advanced fibrosis [160], no significant effect was observed in the non-invasive tests of hepatic fibrosis [161]. Belapectin (GR-MD-02) is now under clinical evaluation, with some initial data reporting its beneficial effect on portal hypertension in patients with compensated liver cirrhosis [162]. Another agent of this category is GB1211, an orally administered drug, which is currently under
safety, tolerability, and pharmacokinetics evaluation in healthy adults and subjects with NASH and hepatic fibrosis (NCT03809052).

4.9. β-selective thyroid hormone receptor (THR) agonists

Thyroid hormone receptor β (THRβ) is predominant in the liver. Activating this receptor showed improved lipid profile without symptoms of thyrotoxicosis, which was mediated by THRα. Resmetirom (MGL-3196), a highly selective THRβ agonist, has been developed to target dyslipidemia [163,164], but it has also been shown to reduce hepatic steatosis in rats. In a phase 2 RCT (NCT02912260), 125 patients with biopsy-proven NASH and ≥10% liver steatosis were assigned to either resmetirom (80 mg) or placebo for 36 weeks [165]. A highly significant reduction in liver fat was observed in patients who received resmetirom compared to those who received placebo. Hepatic inflammation, but not fibrosis, was improved more with resmetirom treatment. Notably, NAS was resolved in higher rates in the resmetirom group than control. Lipid profile, LFTs, adiponectin and serum fibrosis markers were improved in the resmetirom-treated group. Adverse events were generally balanced between groups, except for a higher incidence of transient mild diarrhea and nausea with resmetirom [165]. Based on these findings, a phase 3 RCT in patients with NASH and fibrosis is being developed (MAESTRO-NASH, NCT03900429).

4.10. Caspase inhibitors

TNF-α pathway is a major signaling pathway that drives hepatocyte injury and apoptosis in NASH [166,167]. Caspases are enzymes which are required for the completion of various apoptotic pathways and can be potential therapeutic targets. Emricasan is an oral irreversible pan-caspase inhibitor that has shown to decrease LFTs in patients with chronic hepatitis C [168,169]. In preclinical NASH murine models, emricasan has shown to improve NAS and fibrosis [170]. In a preliminary phase 2 study performed in patients with non- cirrhotic NAFLD and elevated transaminases, emricasan-treated groups demonstrated decrease in LFTs and serum cytokeratin-18 fragments, a marker of liver apoptosis [171]. These results led to 18-month, phase 2b RCT (n=318) that evaluated the efficacy of emricasan (5 mg or 50 mg) vs. placebo in patients with biopsy-proven NASH and fibrosis (F1-F3) (ENCORE-NF) [172]. However, emricasan did not meet the primary endpoint of this study, being the improvement in fibrosis without worsening of NASH, or the secondary endpoint, being NASH resolution without worsening of fibrosis [172]. Emricasan improved steatosis in higher rates (20.0% and 25.8% in the 5 mg and 50 mg groups, respectively) than placebo (12.9%). On the contrary, more placebo-treated patients improved ballooning, lobular inflammation and NAS compared with the emricasan-treated groups [172]. In another 1-year, phase 2 RCT (n=263), emricasan (5 mg or 25 mg or 50 mg) or placebo were administered in patients with NASH-related cirrhosis and severe portal hypertension (ENCORE-PH) [173]. Emricasan also failed to meet the primary endpoint of this study, being the improvement in hepatic venous pressure gradient (HVPG). However, patients with compensated cirrhosis and higher baseline HVPG had a small treatment effect. Furthermore, LFTs, cytokeratin-18 and liver stiffness, being secondary endpoints, were improved after emricasan treatment [173]. There is also an ongoing RCT evaluating the efficacy of emricasan in reducing the event-free survival in patients with decompensated NASH-related cirrhosis (ENCORE-LF; NCT03205345; Table 2).

4.11. Selective mineralocorticoid receptor antagonists

Like spironolactone, eplerenone, a selective MRA, improved hepatic steatosis and fibrosis in mouse models of NAFLD/NASH [174,175]. However, to the best of our knowledge, there is no ongoing study evaluating eplerenone in NASH. Another selective, non-steroidal MRA, apararenone (MT-3995), is currently on a phase 2 RCT in NASH patients; the primary endpoint of this RCT is the 24-week change in ALT (NCT02923154).

4.12. Adipokines

Adipokines are peptides produced and secreted by the adipose tissue. Variation of adipokines occurring during the expansion of adipose tissue have been associated with the pathogenesis of SS and NASH and the progression to advanced disease [9]. Two well-studied adipokines in NAFLD are leptin and adiponectin [123,176]. Leptin levels seem to progressively increase [177], whereas adiponectin levels progressively decrease [178] with disease severity. This association raised expectations for a therapeutic potential of leptin and adiponectin in NASH. Pilot studies of leptin, using recombinant leptin (i.e., metreleptin), which is currently commercially available for the treatment of some forms of congenital and acquired lipodystrophy, are ongoing in subjects with absolute or relative hypoleptinemia and NASH and results are expected soon [179]. However, most NAFLD patients are obese and have hyperleptinemia. In those patients, leptin administration is expected to have minimal or null effect(s) on hepatic histology [180]. Furthermore, based on animal models, excess of leptin could potentially affect hepatic fibrosis adversely, but this has not yet been shown in studies in humans [181]. Therefore, metreleptin investigation is apparently warranted in the minority of NASH patients with hypoleptinemia, in whom leptin replacement is expected to have beneficial effects in hepatic histology, similarly to its effects on other metabolic aberrations, i.e. glucose dysregulation and dyslipidemia [179].
Adiponectin would also be an appealing therapeutic target for NASH. Indeed, recombinant adiponectin was shown to exert hepatoprotective effects in mouse models of NASH [182,183]. Since adiponectin is secreted in complex multimers and is subjected to multiple post-translational modifications before secretion, the production of functionally active recombinant adiponectin has been proven to be extremely difficult [184,185]. Alternatively, adiponectin analogues, such as osmotin [186], or medications that upregulate endogenous adiponectin production (e.g., pioglitazone, INT131) [38], or small molecules that act as adiponectin receptor agonists may be developed and tested for NASH [187,188].

5. Closing remarks

NAFLD is a highly prevalent disease without any approved pharmacological treatment to date. Current guidelines recommend, under specific restrictions, pioglitazone or vitamin E in patients with NASH and significant fibrosis [27,35], but the use of both medications remains off-label. Based on these considerations, developing novel NASH therapeutics remains highly appealing since it has been estimated that the market for approved drugs for NASH may be worth US $ 25 billion in the USA, Japan, and European Union-5 (England, France, Germany, Italy and Spain) in 2026 [189]. Therefore, the explosion in the drug development pipeline is not unexpected, with more than 300 agents being in clinical trials for NASH in 2018 [190]. Some of these medications are in phase 3 clinical trials, as summarized in Table 2. Therefore, we estimate that we are not far from the era of the first pharmacological approval for NASH. OCA may be closer to determination of approval or not in relation to other medications in the pipeline, since the final results of REGENARATE (Table 2) are expected in the near future.
A significant amount of research is also ongoing in the field of PPARs and SPPARMs. Dual or pan-PPAR agonists, including elafibranor, saroglitazar and lanifibranor, targeting simultaneously more than one PPAR, in contrast to pioglitazone that targets only PPAR-γ are currently under investigation. SPPARMs, including INT131 and pemafibrate, are expected to exhibit beneficial effects similar to those of pioglitazone, but with none or minimal of its adverse effects on weight, bone metabolism and bladder.

Many medications to date have failed to provide beneficial effects on hepatic histology, whereas this was highly expected from a pathophysiological viewpoint and/or after successful preclinical studies. Such medications include, but are not limited to metformin, fibrates, omega-3 polyunsaturated fatty acids, pentoxifylline and probiotics. For example, metformin decreases IR and hepatic de novo lipogenesis, whereas it increases fatty acid oxidation [191]. These properties together with its low cost and safe profile would render metformin an ideal candidate for the treatment of NASH. Nonetheless, no robust data for its effect on hepatic histology were reached in clinical trials [191]. Another example is fibrates, PPAR-α agonists primarily targeting hypertriglyceridemia, which is closely related to the pathophysiology of NAFLD. Again, the effect of fibrates on hepatic histology was rather neutral [11]. Probiotics provided favorable preclinical data on NAFLD, but clinical data remain controversial and largely limited by the different formulas and dosage schemes used
in different studies, as well as the diversity and heterogeneity of gut microbiota in different human populations [11]. In a meta-analysis of nine RCTs, probiotics were shown to decrease LFTs [192]. However, in a recent study, a symbiotic combination (probiotic and prebiotic) did not reduce liver fat content or markers of liver fibrosis, despite affecting the fecal microbiome [193]. Until data from ongoing clinical trials become available, the use of probiotics is not recommended for the treatment of NASH.

Anti-obesity medications, including orlistat and liraglutide, have provided beneficial effects on hepatic histology, at least on hepatic steatosis and possibly on inflammation [5]. It seems that weight loss is the main driving force for most of these medications. Therefore, in the cases of weight regain, e.g., after the discontinuation of any anti-obesity medication, any beneficial effect on hepatic histology soon disappears [5]. The effect of many medications approved for obesity on hepatic histology has not yet been investigated. Such medications include phentermine, lorcaserin and the combinations phentermine/topiramate and bupropion/naltrexone. Importantly, most of the anti-obesity medications can achieve a 3-8% mean weight loss and then they reach a plateau [5]. This means that in most cases they cannot help patients achieve at least 10% weight loss, an important cut-off point, which is required for the improvement in fibrosis, as mentioned above. This cut-off can be achieved via bariatric surgery, which may be performed in selected NASH individuals and leads to NASH resolution in most of them. However, there are still considerations about the potential worsening of hepatic histology in some morbidly obese individuals observed after drastic weight loss induced by bariatric surgery [5] and a full cost effectiveness analysis has not been performed. The response to any treatment is usually depended on the underlying mechanism of action of any medication. In this regard, certain medications primarily target the metabolic derangements (e.g., TZDs, GLP-1 RA, SGLT-2), whereas other primarily target liver damage, i.e., anti-fibrotic medications (e.g., CCR2/5 antagonists, ASK1 inhibitors). Based on these different primary targets, it is not unexpected that the former are more effective on steatosis, whereas the latter on fibrosis (Table 1). Combination treatments targeting for example metabolic derangements and liver fibrosis at the same time, by using, for example, pioglitazone (or a SPPARM) and cenicriviroc, or liraglutide and selonsertib, may prove to be more suitable for NASH in the long term. This multifactorial management seems to be rational given the multiple-hit pathogenesis of the disease, but whether this will be translated into therapeutic advances remains to be shown by future clinical trials [15,194].

While waiting for the approval of medications for NASH, a diabetes-like approach should be possibly considered and followed, i.e., the management of other metabolic comorbidities of NASH patients in the setting of the IR syndrome, by using an individualized approach [15,194]. In this regard, special care should be taken to control weight, glucose, lipids and arterial pressure, since their appropriate management may be beneficial for the regression of NASH. Although cut-offs specifically for NASH patients do not exist for all these metabolic parameters, the established cut-offs for patients with T2DM may be adopted, given the close relationship between NAFLD and T2DM [11] .Efforts to develop noninvasive diagnostic tests with high sensitivity and specificity, and efforts to enhance awareness and encourage screening programs for the diagnosis and the prevention or treatment of the disease, which may decrease the disease burden in terms of cardiovascular and hepatic morbidity and mortality, need to be created and propagated. Policies and protocols may serve the patients better by targeting regression of the disease in its earlier stages, before the need of usually costly novel medications. Engagement in weight loss strategies with the promotion of healthier dietary habits and support of sustained exercise programs may sideline the extensive need of expensive medications for NASH. In conclusion, advances in pathophysiology and pharmacology will drive the treatment of NASH in the near future, when more than one safe and effective medications are expected to be approved.

Funding: No sources of financial support for this study.

Disclosure statement

SAP: No conflict of interest ESK: No conflict of interest CB: No conflict of interest EJR: No conflict of interest
CSM: served as a consultant for Aegerion, Regeneron, Coherus, Genfit and NovoNordisk, has received grants through his Institution by Coherus, Novo Nordisk and Esai and is shareholder of Coherus, Pangea Inc.


[1] Fazel Y, Koenig AB, Sayiner M, Goodman ZD, Younossi ZM. Epidemiology and natural history of nonalcoholic fatty liver disease. Metabolism 2016;65:1017-25.
[2] Polyzos SA, Kountouras J, Mantzoros CS. Adipose tissue, obesity and non-alcoholic fatty liver disease. Minerva Endocrinol 2017;42:92-108.
[3] Khan RS, Newsome PN. Non-alcoholic fatty liver disease and liver transplantation. Metabolism 2016;65:1208-23.
[4] Rinella ME. Nonalcoholic fatty liver disease: a systematic review. JAMA 2015;313:2263- 73.
[5] Polyzos SA, Kountouras J, Mantzoros CS. Obesity and nonalcoholic fatty liver disease: From pathophysiology to therapeutics. Metabolism 2019;92:82-97.
[6] Buzzetti E, Pinzani M, Tsochatzis EA. The multiple-hit pathogenesis of non-alcoholic fatty liver disease (NAFLD). Metabolism 2016;65:1038-48.
[7] Mota M, Banini BA, Cazanave SC, Sanyal AJ. Molecular mechanisms of lipotoxicity and glucotoxicity in nonalcoholic fatty liver disease. Metabolism 2016;65:1049-61.
[8] Maradana MR, Yekollu SK, Zeng B, Ellis J, Clouston A, Miller G, et al. Immunomodulatory liposomes targeting liver macrophages arrest progression of nonalcoholic steatohepatitis. Metabolism 2018;78:80-94.
[9] Polyzos SA, Kountouras J, Mantzoros CS. Adipokines in nonalcoholic fatty liver disease. Metabolism 2016;65:1062-79.
[10] Younossi Z, Anstee QM, Marietti M, Hardy T, Henry L, Eslam M, et al. Global burden of NAFLD and NASH: trends, predictions, risk factors and prevention. Nat Rev Gastroenterol Hepatol 2018;15:11-20.
[11] Mintziori G, Polyzos SA. Emerging and future therapies for nonalcoholic steatohepatitis in adults. Expert Opin Pharmacother 2016;17:1937-46.
[12] Barb D, Portillo-Sanchez P, Cusi K. Pharmacological management of nonalcoholic fatty liver disease. Metabolism 2016;65:1183-95.
[13] Rinella ME, Tacke F, Sanyal AJ, Anstee QM. Report on the AASLD/EASL Joint Workshop on Clinical Trial Endpoints in NAFLD. Hepatology 2019;70:1424-36.
[14] Hagstrom H, Nasr P, Ekstedt M, Hammar U, Stal P, Hultcrantz R, et al. Fibrosis stage but not NASH predicts mortality and time to development of severe liver disease in biopsy- proven NAFLD. J Hepatol 2017;67:1265-73.
[15] Polyzos SA, Kountouras J, Zavos C, Deretzi G. Nonalcoholic fatty liver disease: Multimodal treatment options for a pathogenetically multiple-hit disease. J Clin Gastroenterol 2012;46:272-84.
[16] Perakakis N, Polyzos SA, Yazdani A, Sala-Vila A, Kountouras J, Anastasilakis AD, et al. Non-invasive diagnosis of non-alcoholic steatohepatitis and fibrosis with the use of omics and supervised learning: A proof of concept study. Metabolism 2019;101:154005.
[17] Ranjbar G, Mikhailidis DP, Sahebkar A. Effects of newer antidiabetic drugs on nonalcoholic fatty liver and steatohepatitis: Think out of the box! Metabolism 2019;101:154001.
[18] Leoni S, Tovoli F, Napoli L, Serio I, Ferri S, Bolondi L. Current guidelines for the management of non-alcoholic fatty liver disease: A systematic review with comparative analysis. World J Gastroenterol 2018;24:3361-73.
[19] Vilar-Gomez E, Martinez-Perez Y, Calzadilla-Bertot L, Torres-Gonzalez A, Gra-Oramas B, Gonzalez-Fabian L, et al. Weight Loss Through Lifestyle Modification Significantly Reduces Features of Nonalcoholic Steatohepatitis. Gastroenterology 2015;149:367-78.
[20] Hannah WN, Jr., Harrison SA. Effect of Weight Loss, Diet, Exercise, and Bariatric Surgery on Nonalcoholic Fatty Liver Disease. Clin Liver Dis 2016;20:339-50.
[21] Younossi ZM, Stepanova M, Negro F, Hallaji S, Younossi Y, Lam B, et al. Nonalcoholic fatty liver disease in lean individuals in the United States. Medicine 2012;91:319-27.
[22] Argo CK, Henry ZH. Editorial: “Lean” NAFLD: Metabolic Obesity with Normal BMI… Is It in the Genes? Am J Gastroenterol 2017;112:111-3.
[23] Polyzos SA, Kountouras J, Zavos C. Nonalcoholic fatty liver disease: the pathogenetic roles of insulin resistance and adipocytokines. Curr Mol Med 2009;72:299-314.
[24] Katsagoni CN, Georgoulis M, Papatheodoridis GV, Panagiotakos DB, Kontogianni MD. Effects of lifestyle interventions on clinical characteristics of patients with non-alcoholic fatty liver disease: A meta-analysis. Metabolism 2017;68:119-32.
[25] Ahn J, Jun DW, Lee HY, Moon JH. Critical appraisal for low-carbohydrate diet in nonalcoholic fatty liver disease: Review and meta-analyses. Clin Nutr 2019;38:2023-30.
[26] Hashida R, Kawaguchi T, Bekki M, Omoto M, Matsuse H, Nago T, et al. Aerobic vs. resistance exercise in non-alcoholic fatty liver disease: A systematic review. J Hepatol 2017;66:142-52.
[27] EASL–EASD–EASO. EASL-EASD-EASO Clinical Practice Guidelines for the management of non-alcoholic fatty liver disease. Diabetologia 2016;59:1121-40.
[28] Boutari C, Polyzos SA, Mantzoros CS. Of mice and men: Why progress in the pharmacological management of obesity is slower than anticipated and what could be done about it? Metabolism 2019;96:vi-xi.
[29] Pilitsi E, Farr OM, Polyzos SA, Perakakis N, Nolen-Doerr E, Papathanasiou AE, et al. Pharmacotherapy of obesity: Available medications and drugs under investigation. Metabolism 2018;92:170-92.
[30] Sanyal AJ, Chalasani N, Kowdley KV, McCullough A, Diehl AM, Bass NM, et al. Pioglitazone, vitamin E, or placebo for nonalcoholic steatohepatitis. N Engl J Med 2010;362:1675-85.
[31] Hoofnagle JH, Van Natta ML, Kleiner DE, Clark JM, Kowdley KV, Loomba R, et al. Vitamin E and changes in serum alanine aminotransferase levels in patients with non- alcoholic steatohepatitis. Aliment Pharmacol Ther 2013;38:134-43.
[32] Musso G, Gambino R, Cassader M, Pagano G. A meta-analysis of randomized trials for the treatment of nonalcoholic fatty liver disease. Hepatology 2010;52:79-104.
[33] Miller ER, Pastor-Barriuso R, Dalal D, Riemersma RA, Appel LJ, Guallar E. Meta- Analysis: High-Dosage Vitamin E Supplementation May Increase All-Cause Mortality. Ann Intern Med 2005;142:37-46.
[34] Klein EA, Thompson IM, Tangen CM, Crowley JJ, Lucia MS, Goodman PJ, et al. Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA 2011;306:1549-56.
[35] Chalasani N, Younossi Z, Lavine JE, Charlton M, Cusi K, Rinella M, et al. The diagnosis and management of nonalcoholic fatty liver disease: Practice guidance from the American Association for the Study of Liver Diseases. Hepatology 2018;67:328-57.
[36] KASL. KASL clinical practice guidelines: management of nonalcoholic fatty liver disease. Clin Mol Hepatol 2013;19:325-48.
[37] Upadhyay J, Polyzos SA, Perakakis N, Thakkar B, Paschou SA, Katsiki N, et al. Pharmacotherapy of type 2 diabetes: An update. Metabolism 2018;78:13-42.
[38] Polyzos SA, Mantzoros CS. Adiponectin as a target for the treatment of nonalcoholic steatohepatitis with thiazolidinediones: A systematic review. Metabolism 2016;65:1297-306.
[39] Singh S, Khera R, Allen AM, Murad MH, Loomba R. Comparative effectiveness of pharmacological interventions for nonalcoholic steatohepatitis: A systematic review and network meta-analysis. Hepatology 2015;62:1417-32.
[40] Musso G, Cassader M, Rosina F, Gambino R. Impact of current treatments on liver disease, glucose metabolism and cardiovascular risk in non-alcoholic fatty liver disease (NAFLD): a systematic review and meta-analysis of randomised trials. Diabetologia 2012;55:885-904.
[41] Mahady SE, Webster AC, Walker S, Sanyal A, George J. The role of thiazolidinediones in non-alcoholic steatohepatitis – a systematic review and meta analysis. J Hepatol 2011;55:1383-90.
[42] Cusi K, Orsak B, Bril F, Lomonaco R, Hecht J, Ortiz-Lopez C, et al. Long-Term Pioglitazone Treatment for Patients With Nonalcoholic Steatohepatitis and Prediabetes or Type 2 Diabetes Mellitus: A Randomized, Controlled Trial. Ann Intern Med 2016;165:305- 15.
[43] Lutchman G, Modi A, Kleiner DE, Promrat K, Heller T, Ghany M, et al. The effects of discontinuing pioglitazone in patients with nonalcoholic steatohepatitis. Hepatology 2007;46:424-9.
[44] Nissen SE, Wolski K. Rosiglitazone revisited: an updated meta-analysis of risk for myocardial infarction and cardiovascular mortality. Arch Intern Med 2010;170:1191-201.
[45] Tang H, Shi W, Fu S, Wang T, Zhai S, Song Y, et al. Pioglitazone and bladder cancer risk: a systematic review and meta-analysis. Cancer Med 2018;7:1070-80.
[46] Davidson MB, Pan D. An updated meta-analysis of pioglitazone exposure and bladder cancer and comparison to the drug’s effect on cardiovascular disease and non-alcoholic steatohepatitis. Diabetes Res Clin Pract 2018;135:102-10.
[47] Lewis JD, Habel LA, Quesenberry CP, Strom BL, Peng T, Hedderson MM, et al. Pioglitazone Use and Risk of Bladder Cancer and Other Common Cancers in Persons With Diabetes. JAMA 2015;314:265-77.
[48] Kao LT, Xirasagar S, Lin HC, Huang CY. Association Between Pioglitazone Use and Prostate Cancer: A Population-Based Case-Control Study in the Han Population. J Clin Pharmacol 2019;59:344-9.
[49] Elmaci I, Altinoz MA. A Metabolic Inhibitory Cocktail for Grave Cancers: Metformin, Pioglitazone and Lithium Combination in Treatment of Pancreatic Cancer and Glioblastoma Multiforme. Biochem Genet 2016;54:573-618.
[50] Armstrong MJ, Hull D, Guo K, Barton D, Hazlehurst JM, Gathercole LL, et al. Glucagon-like peptide 1 decreases lipotoxicity in non-alcoholic steatohepatitis. J Hepatol 2016;64:399-408.
[51] Gastaldelli A, Gaggini M, Daniele G, Ciociaro D, Cersosimo E, Tripathy D, et al. Exenatide improves both hepatic and adipose tissue insulin resistance: A dynamic positron emission tomography study. Hepatology 2016;64:2028-37.
[52] Armstrong MJ, Gaunt P, Aithal GP, Barton D, Hull D, Parker R, et al. Liraglutide safety and efficacy in patients with non-alcoholic steatohepatitis (LEAN): a multicentre, double- blind, randomised, placebo-controlled phase 2 study. Lancet 2016;387:679-90.
[53] Armstrong MJ, Houlihan DD, Rowe IA, Clausen WH, Elbrond B, Gough SC, et al. Safety and efficacy of liraglutide in patients with type 2 diabetes and elevated liver enzymes: individual patient data meta-analysis of the LEAD program. Aliment Pharmacol Ther 2013;37:234-42.
[54] Eguchi Y, Kitajima Y, Hyogo H, Takahashi H, Kojima M, Ono M, et al. Pilot study of liraglutide effects in non-alcoholic steatohepatitis and non-alcoholic fatty liver disease with glucose intolerance in Japanese patients (LEAN-J). Hepatol Res 2015;45:269-78.
[55] Petit JM, Cercueil JP, Loffroy R, Denimal D, Bouillet B, Fourmont C, et al. Effect of Liraglutide Therapy on Liver Fat Content in Patients With Inadequately Controlled Type 2 Diabetes: The Lira-NAFLD Study. J Clin Endocrinol Metab 2017;102:407-15.
[56] Kenny PR, Brady DE, Torres DM, Ragozzino L, Chalasani N, Harrison SA. Exenatide in the treatment of diabetic patients with non-alcoholic steatohepatitis: a case series. Am J Gastroenterol 2010;105:2707-9.
[57] Shao N, Kuang HY, Hao M, Gao XY, Lin WJ, Zou W. Benefits of exenatide on obesity and non-alcoholic fatty liver disease with elevated liver enzymes in patients with type 2 diabetes. Diabetes Metab Res Rev 2014;30:521-9.
[58] Seko Y, Sumida Y, Tanaka S, Mori K, Taketani H, Ishiba H, et al. Effect of 12-week dulaglutide therapy in Japanese patients with biopsy-proven non-alcoholic fatty liver disease and type 2 diabetes mellitus. Hepatol Res 2017;47:1206-11.
[59] Iwasaki T, Yoneda M, Inamori M, Shirakawa J, Higurashi T, Maeda S, et al. Sitagliptin as a novel treatment agent for non-alcoholic Fatty liver disease patients with type 2 diabetes mellitus. Hepatogastroenterology 2011;58:2103-5.
[60] Alam S, Ghosh J, Mustafa G, Kamal M, Ahmad N. Effect of sitagliptin on hepatic histological activity and fibrosis of nonalcoholic steatohepatitis patients: a 1-year randomized control trial. Hepat Med 2018;10:23-31.
[61] Macauley M, Hollingsworth KG, Smith FE, Thelwall PE, Al-Mrabeh A, Schweizer A, et al. Effect of vildagliptin on hepatic steatosis. J Clin Endocrinol Metab 2015;100:1578-85.
[62] Fukuhara T, Hyogo H, Ochi H, Fujino H, Kan H, Naeshiro N, et al. Efficacy and safety of sitagliptin for the treatment of nonalcoholic fatty liver disease with type 2 diabetes mellitus. Hepatogastroenterology 2014;61:323-8.
[63] Cui J, Philo L, Nguyen P, Hofflich H, Hernandez C, Bettencourt R, et al. Sitagliptin vs. placebo for non-alcoholic fatty liver disease: A randomized controlled trial. J Hepatol 2016;65:369-76.
[64] Kato H, Nagai Y, Ohta A, Tenjin A, Nakamura Y, Tsukiyama H, et al. Effect of sitagliptin on intrahepatic lipid content and body fat in patients with type 2 diabetes. Diabetes Res Clin Pract 2015;109:199-205.
[65] Joy TR, McKenzie CA, Tirona RG, Summers K, Seney S, Chakrabarti S, et al. Sitagliptin in patients with non-alcoholic steatohepatitis: A randomized, placebo-controlled trial. World J Gastroenterol 2017;23:141-50.
[66] Zinman B, Wanner C, Lachin JM, Fitchett D, Bluhmki E, Hantel S, et al. Empagliflozin, Cardiovascular Outcomes, and Mortality in Type 2 Diabetes. N Engl J Med 2015;373:2117- 28.
[67] Neal B, Perkovic V, Mahaffey KW, de Zeeuw D, Fulcher G, Erondu N, et al. Canagliflozin and Cardiovascular and Renal Events in Type 2 Diabetes. N Engl J Med 2017;377:644-57.
[68] Wiviott SD, Raz I, Bonaca MP, Mosenzon O, Kato ET, Cahn A, et al. Dapagliflozin and Cardiovascular Outcomes in Type 2 Diabetes. N Engl J Med 2019;380:347-57.
[69] Kuchay MS, Krishan S, Mishra SK, Farooqui KJ, Singh MK, Wasir JS, et al. Effect of Empagliflozin on Liver Fat in Patients With Type 2 Diabetes and Nonalcoholic Fatty Liver Disease: A Randomized Controlled Trial (E-LIFT Trial). Diabetes Care 2018;41:1801-8.
[70] Shimizu M, Suzuki K, Kato K, Jojima T, Iijima T, Murohisa T, et al. Evaluation of the effects of dapagliflozin, a sodium-glucose co-transporter-2 inhibitor, on hepatic steatosis and fibrosis using transient elastography in patients with type 2 diabetes and non-alcoholic fatty liver disease. Diabetes Obes Metab 2019;21:285-92.
[71] Kurinami N, Sugiyama S, Yoshida A, Hieshima K, Miyamoto F, Kajiwara K, et al. Dapagliflozin significantly reduced liver fat accumulation associated with a decrease in abdominal subcutaneous fat in patients with inadequately controlled type 2 diabetes mellitus. Diabetes Res Clin Pract 2018;142:254-63.
[72] Tobita H, Sato S, Miyake T, Ishihara S, Kinoshita Y. Effects of Dapagliflozin on Body Composition and Liver Tests in Patients with Nonalcoholic Steatohepatitis Associated with Type 2 Diabetes Mellitus: A Prospective, Open-label, Uncontrolled Study. Curr Ther Res Clin Exp 2017;87:13-9.
[73] Inoue M, Hayashi A, Taguchi T, Arai R, Sasaki S, Takano K, et al. Effects of canagliflozin on body composition and hepatic fat content in type 2 diabetes patients with non-alcoholic fatty liver disease. J Diabetes Investig 2019;10:1004-11.
[74] Seko Y, Nishikawa T, Umemura A, Yamaguchi K, Moriguchi M, Yasui K, et al. Efficacy and safety of canagliflozin in type 2 diabetes mellitus patients with biopsy-proven nonalcoholic steatohepatitis classified as stage 1-3 fibrosis. Diabetes Metab Syndr Obes 2018;11:835-43.
[75] Cusi K, Bril F, Barb D, Polidori D, Sha S, Ghosh A, et al. Effect of Canagliflozin Treatment on Hepatic Triglyceride Content and Glucose Metabolism in Patients with Type 2 Diabetes. Diabetes Obes Metab 2018; https://doi.org/10.1111/dom.13584.
[76] Miyake T, Yoshida S, Furukawa S, Sakai T, Tada F, Senba H, et al. Ipragliflozin Ameliorates Liver Damage in Non-alcoholic Fatty Liver Disease. Open Med 2018;13:402-9.
[77] Ito D, Shimizu S, Inoue K, Saito D, Yanagisawa M, Inukai K, et al. Comparison of Ipragliflozin and Pioglitazone Effects on Nonalcoholic Fatty Liver Disease in Patients With Type 2 Diabetes: A Randomized, 24-Week, Open-Label, Active-Controlled Trial. Diabetes Care 2017;40:1364-72.
[78] Gastaldelli A, Repetto E, Guja C, Hardy E, Han J, Jabbour SA, et al. Exenatide and dapagliflozin combination improves markers of liver steatosis and fibrosis in patients with type 2 diabetes. Diabetes Obes Metab 2019; https://doi.org/10.1111/dom.13907.
[79] Targher G, Day CP, Bonora E. Risk of cardiovascular disease in patients with nonalcoholic fatty liver disease. N Engl J Med 2010;363:1341-50.
[80] Parra JL, Reddy KR. Hepatotoxicity of hypolipidemic drugs. Clin Liver Dis 2003;7:415- 33.
[81] Athyros VG, Tziomalos K, Gossios TD, Griva T, Anagnostis P, Kargiotis K, et al. Safety and efficacy of long-term statin treatment for cardiovascular events in patients with coronary heart disease and abnormal liver tests in the Greek Atorvastatin and Coronary Heart Disease Evaluation (GREACE) Study: a post-hoc analysis. Lancet 2010;376:1916-22.
[82] Tikkanen MJ, Fayyad R, Faergeman O, Olsson AG, Wun C-C, Laskey R, et al. Effect of intensive lipid lowering with atorvastatin on cardiovascular outcomes in coronary heart disease patients with mild-to-moderate baseline elevations in alanine aminotransferase levels. Int J Cardiol 2013;168:3846-52.
[83] Athyros VG, Ganotakis E, Kolovou GD, Nicolaou V, Achimastos A, Bilianou E, et al. Assessing the treatment effect in metabolic syndrome without perceptible diabetes (ATTEMPT): a prospective-randomized study in middle aged men and women. Curr Vasc Pharmacol 2011;9:647-57.
[84] Athyros VG, Alexandrides TK, Bilianou H, Cholongitas E, Doumas M, Ganotakis ES, et al. The use of statins alone, or in combination with pioglitazone and other drugs, for the treatment of non-alcoholic fatty liver disease/non-alcoholic steatohepatitis and related cardiovascular risk. An Expert Panel Statement. Metabolism 2017;71:17-32.
[85] Dongiovanni P, Petta S, Mannisto V, Mancina RM, Pipitone R, Karja V, et al. Statin use and non-alcoholic steatohepatitis in at risk individuals. J Hepatol 2015;63:705-12.
[86] Kargiotis K, Athyros VG, Giouleme O, Katsiki N, Katsiki E, Anagnostis P, et al. Resolution of non-alcoholic steatohepatitis by rosuvastatin monotherapy in patients with metabolic syndrome. World J Gastroenterol 2015;21:7860-8.
[87] Nascimbeni F, Aron-Wisnewsky J, Pais R, Tordjman J, Poitou C, Charlotte F, et al. Statins, antidiabetic medications and liver histology in patients with diabetes with non- alcoholic fatty liver disease. BMJ Open Gastroenterol 2016;3:e000075.
[88] Hyogo H, Ikegami T, Tokushige K, Hashimoto E, Inui K, Matsuzaki Y, et al. Efficacy of pitavastatin for the treatment of non-alcoholic steatohepatitis with dyslipidemia: An open- label, pilot study. Hepatol Res 2011;41:1057-65.
[89] Nakahara T, Hyogo H, Kimura Y, Ishitobi T, Arihiro K, Aikata H, et al. Efficacy of rosuvastatin for the treatment of non-alcoholic steatohepatitis with dyslipidemia: An open- label, pilot study. Hepatol Res 2012;42:1065-72.
[90] Tziomalos K, Athyros VG, Paschos P, Karagiannis A. Nonalcoholic fatty liver disease and statins. Metabolism 2015;64:1215-23.
[91] Athyros VG, Polyzos SA, Kountouras J, Katsiki N, Anagnostis P, Doumas M, et al. Non- alcoholic fatty liver disease treatment in patients with type 2 diabetes mellitus; new kids on the block. Curr Vasc Pharmacol 2020;18:172-81.
[92] Simon TG, Duberg AS, Aleman S, Hagstrom H, Nguyen LH, Khalili H, et al. Lipophilic Statins and Risk for Hepatocellular Carcinoma and Death in Patients With Chronic Viral Hepatitis: Results From a Nationwide Swedish Population. Ann Intern Med 2019;171:318-27.
[93] Parker HM, Johnson NA, Burdon CA, Cohn JS, O’Connor HT, George J. Omega-3 supplementation and non-alcoholic fatty liver disease: a systematic review and meta-analysis. J Hepatol 2012;56:944-51.
[94] Sanyal AJ, Abdelmalek MF, Suzuki A, Cummings OW, Chojkier M. No significant effects of ethyl-eicosapentanoic acid on histologic features of nonalcoholic steatohepatitis in a phase 2 trial. Gastroenterology 2014;147:377-84.
[95] Scorletti E, Bhatia L, McCormick KG, Clough GF, Nash K, Hodson L, et al. Effects of purified eicosapentaenoic and docosahexaenoic acids in nonalcoholic fatty liver disease: results from the Welcome* study. Hepatology 2014;60:1211-21.
[96] Zelber-Sagi S, Kessler A, Brazowsky E, Webb M, Lurie Y, Santo M, et al. A double- blind randomized placebo-controlled trial of orlistat for the treatment of nonalcoholic fatty liver disease. Clin Gastroenterol Hepatol 2006;4:639-44.
[97] Hussein O, Grosovski M, Schlesinger S, Szvalb S, Assy N. Orlistat reverse fatty infiltration and improves hepatic fibrosis in obese patients with nonalcoholic steatohepatitis (NASH). Dig Dis Sci 2007;52:2512-9.
[98] Harrison SA, Fincke C, Helinski D, Torgerson S, Hayashi P. A pilot study of orlistat treatment in obese, non-alcoholic steatohepatitis patients. Aliment Pharmacol Ther 2004;20:623-8.
[99] Harrison SA, Fecht W, Brunt EM, Neuschwander-Tetri BA. Orlistat for overweight subjects with nonalcoholic steatohepatitis: A randomized, prospective trial. Hepatology 2009;49:80-6.
[100] Wang H, Wang L, Cheng Y, Xia Z, Liao Y, Cao J. Efficacy of orlistat in non-alcoholic fatty liver disease: A systematic review and meta-analysis. Biomed Rep 2018;9:90-6.
[101] Reardon J, Hussaini T, Alsahafi M, Azalgara VM, Erb SR, Partovi N, et al. Ursodeoxycholic Acid in Treatment of Non-cholestatic Liver Diseases: A Systematic Review. J Clin Transl Hepatol 2016;4:192-205.
[102] Neuman M, Angulo P, Malkiewicz I, Jorgensen R, Shear N, Dickson ER, et al. Tumor necrosis factor-α and transforming growth factor-β reflect severity of liver damage in primary biliary cirrhosis. J Gastroenterol Hepatol 2002;17:196-202.
[103] Pathil A, Mueller J, Warth A, Chamulitrat W, Stremmel W. Ursodeoxycholyl lysophosphatidylethanolamide improves steatosis and inflammation in murine models of nonalcoholic fatty liver disease. Hepatology 2012;55:1369-78.
[104] Rodrigues CMP, Fan G, Ma X, Kren BT, Steer CJ. A novel role for ursodeoxycholic acid in inhibiting apoptosis by modulating mitochondrial membrane perturbation. J Clin Invest 1998;101:2790-9.
[105] Xiang Z, Chen Yp, Ma Kf, Ye Yf, Zheng L, Yang Yd, et al. The role of Ursodeoxycholic acid in non-alcoholic steatohepatitis: A systematic review. BMC Gastroenterology 2013;13:140.
[106] Wada T, Kenmochi H, Miyashita Y, Sasaki M, Ojima M, Sasahara M, et al. Spironolactone Improves Glucose and Lipid Metabolism by Ameliorating Hepatic Steatosis and Inflammation and Suppressing Enhanced Gluconeogenesis Induced by High-Fat and High-Fructose Diet. Endocrinology 2010;151:2040-9.
[107] Polyzos SA, Kountouras J, Zafeiriadou E, Patsiaoura K, Katsiki E, Deretzi G, et al. Effect of spironolactone and vitamin E on serum metabolic parameters and insulin resistance in patients with nonalcoholic fatty liver disease. J Renin Angiotensin Aldosterone Syst 2011;12:498-503.
[108] Polyzos SA, Kountouras J, Mantzoros CS, Polymerou V, Katsinelos P. Effects of combined low-dose spironolactone plus vitamin E vs vitamin E monotherapy on insulin resistance, non-invasive indices of steatosis and fibrosis, and adipokine levels in non- alcoholic fatty liver disease: a randomized controlled trial. Diabetes Obes Metab 2017;19:1805-9.
[109] Polyzos SA, Kountouras J, Anastasilakis AD, Makras P, Hawa G, Sonnleitner L, et al. Noggin levels in nonalcoholic fatty liver disease: the effect of vitamin E treatment. Hormones (Athens) 2018;17:573-9.
[110] Polyzos SA, Hawa G, Jungwirth T, Karabouta Z, Kountouras J. Asporin levels are low in patients with nonalcoholic fatty liver disease and increase after vitamin E treatment. Hormones (Athens) 2019;18:519-21.
[111] Lefebvre P, Cariou B, Lien F, Kuipers F, Staels B. Role of bile acids and bile acid receptors in metabolic regulation. Physiol Rev 2009;89:147-91.
[112] Mudaliar S, Henry RR, Sanyal AJ, Morrow L, Marschall HU, Kipnes M, et al. Efficacy and safety of the farnesoid X receptor agonist obeticholic acid in patients with type 2 diabetes and nonalcoholic fatty liver disease. Gastroenterology 2013;145:574-82.
[113] Neuschwander-Tetri BA, Loomba R, Sanyal AJ, Lavine JE, Van Natta ML, Abdelmalek MF, et al. Farnesoid X nuclear receptor ligand obeticholic acid for non-cirrhotic, non-alcoholic steatohepatitis (FLINT): a multicentre, randomised, placebo-controlled trial. Lancet 2015;385:956-65.
[114] Pockros PJ, Fuchs M, Freilich B, Schiff E, Kohli A, Lawitz EJ, et al. CONTROL: a randomized phase 2 study of obeticholic acid and atorvastatin on lipoproteins in nonalcoholic steatohepatitis patients. Liver Int 2019;39:2082-93.
[115] Younossi ZM, Ratziu V, Loomba R, Rinella M, Anstee QM, Goodman Z, et al. Obeticholic acid for the treatment of non-alcoholic steatohepatitis: interim analysis from a multicentre, randomised, placebo-controlled phase 3 trial. Lancet 2019;394:2184-96.
[116] Siddiqui MS, Van Natta ML, Connelly MA, Vuppalanchi R, Neuschwander-Tetri BA, Tonascia J, et al. Impact of obeticholic acid on the lipoprotein profile in patients with non- alcoholic steatohepatitis. J Hepatol 2020;72:25-33.
[117] Lawitz E, Gane E, Ruane P, Herring R, Younes ZH, Kwo P, et al. A combination of the ACC inhibitor GS-0976 and the nonsteroidal FXR agonist GS-9674 improves hepatic steatosis, biochemistry, and stiffness in patients with non-alcoholic steatohepatitis. J Hepatol 2019;70:e794.
[118] Hernandez ED, Zheng L, Kim Y, Fang B, Liu B, Valdez RA, et al. Tropifexor- Mediated Abrogation of Steatohepatitis and Fibrosis Is Associated With the Antioxidative Gene Expression Profile in Rodents. Hepatol Commun 2019;3:1085-97.
[119] Chianelli D, Rucker PV, Roland J, Tully DC, Nelson J, Liu X, et al. Nidufexor (LMB763), a Novel FXR Modulator for the Treatment of Nonalcoholic Steatohepatitis. J Med Chem 2020; https://doi.org/10.1021/acs.jmedchem.9b01621.
[120] Venetsanaki V, Karabouta Z, Polyzos SA. Farnesoid X nuclear receptor agonists for the treatment of nonalcoholic steatohepatitis. Eur J Pharmacol 2019;863:172661.
[121] Staels B, Rubenstrunk A, Noel B, Rigou G, Delataille P, Millatt LJ, et al. Hepatoprotective effects of the dual peroxisome proliferator-activated receptor alpha/delta agonist, GFT505, in rodent models of nonalcoholic fatty liver disease/nonalcoholic steatohepatitis. Hepatology 2013;58:1941-52.
[122] Cariou B, Hanf R, Lambert-Porcheron S, Zair Y, Sauvinet V, Noel B, et al. Dual peroxisome proliferator-activated receptor alpha/delta agonist GFT505 improves hepatic and peripheral insulin sensitivity in abdominally obese subjects. Diabetes Care 2013;36:2923-30.
[123] Polyzos SA, Kountouras J, Zavos C, Tsiaousi E. The role of adiponectin in the pathogenesis and treatment of nonalcoholic fatty liver disease. Diabetes Obes Metab 2010;12:365-83.
[124] Ratziu V, Harrison SA, Francque S, Bedossa P, Lehert P, Serfaty L, et al. Elafibranor, an Agonist of the Peroxisome Proliferator-Activated Receptor-alpha and -delta, Induces Resolution of Nonalcoholic Steatohepatitis Without Fibrosis Worsening. Gastroenterology 2016;150:1147-59.
[125] Jain MR, Giri SR, Bhoi B, Trivedi C, Rath A, Rathod R, et al. Dual PPARalpha/gamma agonist saroglitazar improves liver histopathology and biochemistry in experimental NASH models. Liver Int 2018;38:1084-94.
[126] Kaul U, Parmar D, Manjunath K, Shah M, Parmar K, Patil KP, et al. New dual peroxisome proliferator activated receptor agonist-Saroglitazar in diabetic dyslipidemia and non-alcoholic fatty liver disease: integrated analysis of the real world evidence. Cardiovasc Diabetol 2019;18:80.
[127] Boubia B, Poupardin O, Barth M, Binet J, Peralba P, Mounier L, et al. Design, Synthesis, and Evaluation of a Novel Series of Indole Sulfonamide Peroxisome Proliferator Activated Receptor (PPAR) alpha/gamma/delta Triple Activators: Discovery of Lanifibranor, a New Antifibrotic Clinical Candidate. J Med Chem 2018;61:2246-65.
[128] Lefere S, Puengel T, Krenkel O, Hundertmark J, Adarbes V, Estavilet C, et al. Differential therapeutic effects of pan- and single PPAR agonists on steatosis, inflammation, macrophage composition and fibrosis in a murine model of non-alcoholic steatohepatitis. J Hepatol 2019;70:e8-e9.
[129] Harrison S, Neff G, Iwashita J, Lee J, Lazas D, Cusi K, et al. Six month interim results of MSDC-0602 K in a large phase 2b NASH study demonstrate significant improvement in liver enzymes and glycemic control. J Hepatol 2019;70:e70.
[130] Harrison SA, Alkhouri N, Davison BA, Sanyal A, Edwards C, Colca JR, et al. Insulin sensitizer MSDC-0602K in non-alcoholic steatohepatitis: A randomized, double-blind, placebo-controlled phase IIb study. J Hepatol 2019; https://doi.org/10.1016/j.jhep.2019.10.023.
[131] Higgins LS, Mantzoros CS. The Development of INT131 as a Selective PPARgamma Modulator: Approach to a Safer Insulin Sensitizer. PPAR Res 2008;2008:936906.
[132] Dunn FL, Higgins LS, Fredrickson J, DePaoli AM. Selective modulation of PPARgamma activity can lower plasma glucose without typical thiazolidinedione side-effects in patients with Type 2 diabetes. J Diabetes Complications 2011;25:151-8.
[133] DePaoli AM, Higgins LS, Henry RR, Mantzoros C, Dunn FL. Can a selective PPARgamma modulator improve glycemic control in patients with type 2 diabetes with fewer side effects compared with pioglitazone? Diabetes Care 2014;37:1918-23.
[134] Honda Y, Kessoku T, Ogawa Y, Tomeno W, Imajo K, Fujita K, et al. Pemafibrate, a novel selective peroxisome proliferator-activated receptor alpha modulator, improves the pathogenesis in a rodent model of nonalcoholic steatohepatitis. Sci Rep 2017;7:42477.
[135] Ishibashi S, Arai H, Yokote K, Araki E, Suganami H, Yamashita S. Efficacy and safety of pemafibrate (K-877), a selective peroxisome proliferator-activated receptor alpha modulator, in patients with dyslipidemia: Results from a 24-week, randomized, double blind, active-controlled, phase 3 trial. J Clin Lipidol 2018;12:173-84.
[136] Tamura Y, Sugimoto M, Murayama T, Minami M, Nishikaze Y, Ariyasu H, et al. C-C chemokine receptor 2 inhibitor improves diet-induced development of insulin resistance and hepatic steatosis in mice. J Atheroscler Thromb 2010;17:219-28.
[137] Lefebvre E, Moyle G, Reshef R, Richman LP, Thompson M, Hong F, et al. Antifibrotic Effects of the Dual CCR2/CCR5 Antagonist Cenicriviroc in Animal Models of Liver and Kidney Fibrosis. PLoS One 2016;11:e0158156.
[138] Friedman SL, Ratziu V, Harrison SA, Abdelmalek MF, Aithal GP, Caballeria J, et al. A randomized, placebo-controlled trial of cenicriviroc for treatment of nonalcoholic steatohepatitis with fibrosis. Hepatology 2018;67:1754-67.
[139] Ratziu V, Sanyal A, Harrison SA, Wong VW, Francque S, Goodman Z, et al. Cenicriviroc Treatment for Adults with Nonalcoholic Steatohepatitis and Fibrosis: Final Analysis of the Phase 2b CENTAUR Study. Hepatology 2020; https://doi.org/10.1002/hep.31108.
[140] Tacke F. Cenicriviroc for the treatment of non-alcoholic steatohepatitis and liver fibrosis. Expert Opin Investig Drugs 2018;27:301-11.
[141] Brenner C, Galluzzi L, Kepp O, Kroemer G. Decoding cell death signals in liver inflammation. J Hepatol 2013;59:583-94.
[142] Xiang M, Wang PX, Wang AB, Zhang XJ, Zhang Y, Zhang P, et al. Targeting hepatic TRAF1-ASK1 signaling to improve inflammation, insulin resistance, and hepatic steatosis. J Hepatol 2016;64:1365-77.
[143] Loomba R, Lawitz E, Mantry PS, Jayakumar S, Caldwell SH, Arnold H, et al. The ASK1 inhibitor selonsertib in patients with nonalcoholic steatohepatitis: A randomized, phase 2 trial. Hepatology 2018;67:549-59.
[144] Vila-Brau A, De Sousa-Coelho AL, Mayordomo C, Haro D, Marrero PF. Human HMGCS2 regulates mitochondrial fatty acid oxidation and FGF21 expression in HepG2 cell line. J Biol Chem 2011;286:20423-30.
[145] Kharitonenkov A, Shiyanova TL, Koester A, Ford AM, Micanovic R, Galbreath EJ, et al. FGF-21 as a novel metabolic regulator. J Clin Invest 2005;115:1627-35.
[146] Gaich G, Chien JY, Fu H, Glass LC, Deeg MA, Holland WL, et al. The effects of LY2405319, an FGF21 analog, in obese human subjects with type 2 diabetes. Cell Metab 2013;18:333-40.
[147] Talukdar S, Zhou Y, Li D, Rossulek M, Dong J, Somayaji V, et al. A Long-Acting FGF21 Molecule, PF-05231023, Decreases Body Weight and Improves Lipid Profile in Non- human Primates and Type 2 Diabetic Subjects. Cell Metab 2016;23:427-40.
[148] Sanyal A, Charles ED, Neuschwander-Tetri BA, Loomba R, Harrison SA, Abdelmalek MF, et al. Pegbelfermin (BMS-986036), a PEGylated fibroblast growth factor 21 analogue, in patients with non-alcoholic steatohepatitis: a randomised, double-blind, placebo-controlled, phase 2a trial. Lancet 2019;392:2705-17.
[149] Itoh N, Nakayama Y, Konishi M. Roles of FGFs As Paracrine or Endocrine Signals in Liver Development, Health, and Disease. Front Cell Dev Biol 2016;4:30.
[150] Lawitz EJ, Coste A, Poordad F, Alkhouri N, Loo N, McColgan BJ, et al. Acetyl-CoA Carboxylase Inhibitor GS-0976 for 12 Weeks Reduces Hepatic De Novo Lipogenesis and Steatosis in Patients With Nonalcoholic Steatohepatitis. Clin Gastroenterol Hepatol 2018;16:1983-91.
[151] Loomba R, Kayali Z, Noureddin M, Ruane P, Lawitz EJ, Bennett M, et al. GS-0976 Reduces Hepatic Steatosis and Fibrosis Markers in Patients With Nonalcoholic Fatty Liver Disease. Gastroenterology 2018;155:1463-73.
[152] Goedeke L, Bates J, Vatner DF, Perry RJ, Wang T, Ramirez R, et al. Acetyl-CoA Carboxylase Inhibition Reverses NAFLD and Hepatic Insulin Resistance but Promotes Hypertriglyceridemia in Rodents. Hepatology 2018;68:2197-211.
[153] Kim CW, Addy C, Kusunoki J, Anderson NN, Deja S, Fu X, et al. Acetyl CoA Carboxylase Inhibition Reduces Hepatic Steatosis but Elevates Plasma Triglycerides in Mice and Humans: A Bedside to Bench Investigation. Cell Metab 2017;26:394-406.
[154] Kagan HM, Li W. Lysyl oxidase: properties, specificity, and biological roles inside and outside of the cell. J Cell Biochem 2003;88:660-72.
[155] Kagan HM. Lysyl oxidase: mechanism, regulation and relationship to liver fibrosis. Pathol Res Pract 1994;190:910-9.
[156] Barry-Hamilton V, Spangler R, Marshall D, McCauley S, Rodriguez HM, Oyasu M, et al. Allosteric inhibition of lysyl oxidase-like-2 impedes the development of a pathologic microenvironment. Nat Med 2010;16:1009-17.
[157] Harrison SA, Abdelmalek MF, Caldwell S, Shiffman ML, Diehl AM, Ghalib R, et al. Simtuzumab is ineffective for patients with bridging fibrosis or compensated cirrhosis caused by nonalcoholic steatohepatitis. Gastroenterology 2018;155:1140-53.
[158] Tacke F. Targeting hepatic macrophages to treat liver diseases. J Hepatol 2017;66:1300-12.
[159] Traber PG, Chou H, Zomer E, Hong F, Klyosov A, Fiel MI, et al. Regression of Fibrosis and Reversal of Cirrhosis in Rats by Galectin Inhibitors in Thioacetamide-Induced Liver Disease. PLoS One 2013;8:e75361.
[160] Harrison SA, Marri SR, Chalasani N, Kohli R, Aronstein W, Thompson GA, et al. Randomised clinical study: GR-MD-02, a galectin-3 inhibitor, vs. placebo in patients having non-alcoholic steatohepatitis with advanced fibrosis. Aliment Pharmacol Ther 2016;44:1183- 98.
[161] Harrison SA, Dennis A, Fiore MM, Kelly MD, Kelly CJ, Paredes AH, et al. Utility and variability of three non-invasive liver fibrosis imaging modalities to evaluate efficacy of GR- MD-02 in subjects with NASH and bridging fibrosis during a phase-2 randomized clinical trial. PloS One 2018;13:e0203054.
[162] Konerman MA, Jones JC, Harrison SA. Pharmacotherapy for NASH: Current and emerging. J Hepatol 2018;68:362-75.
[163] Kelly MJ, Pietranico-Cole S, Larigan JD, Haynes NE, Reynolds CH, Scott N, et al. Discovery of 2-[3,5-dichloro-4-(5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yloxy)phenyl]- 3,5-dio xo-2,3,4,5-tetrahydro[1,2,4]triazine-6-carbonitrile (MGL-3196), a Highly Selective Thyroid Hormone Receptor beta agonist in clinical trials for the treatment of dyslipidemia. J Med Chem 2014;57:3912-23.
[164] Taub R, Chiang E, Chabot-Blanchet M, Kelly MJ, Reeves RA, Guertin MC, et al. Lipid lowering in healthy volunteers treated with multiple doses of MGL-3196, a liver-targeted thyroid hormone receptor-beta agonist. Atherosclerosis 2013;230:373-80.
[165] Harrison SA, Bashir MR, Guy CD, Zhou R, Moylan CA, Frias JP, et al. Resmetirom (MGL-3196) for the treatment of non-alcoholic steatohepatitis: a multicentre, randomised, double-blind, placebo-controlled, phase 2 trial. Lancet 2019;394:2012-24.
[166] Syn WK, Choi SS, Diehl AM. Apoptosis and cytokines in non-alcoholic steatohepatitis. Clin Liver Dis 2009;13:565-80.
[167] Feldstein AE, Gores GJ. Apoptosis in alcoholic and nonalcoholic steatohepatitis. Front Biosci 2005;10:3093-9.
[168] Pockros PJ, Schiff ER, Shiffman ML, McHutchison JG, Gish RG, Afdhal NH, et al. Oral IDN-6556, an antiapoptotic caspase inhibitor, may lower aminotransferase activity in patients with chronic hepatitis C. Hepatology 2007;46:324-9.
[169] Shiffman ML, Pockros P, McHutchison JG, Schiff ER, Morris M, Burgess G. Clinical trial: the efficacy and safety of oral PF-03491390, a pancaspase inhibitor – a randomized placebo-controlled study in patients with chronic hepatitis C. Aliment Pharmacol Ther 2010;31:969-78.
[170] Barreyro FJ, Holod S, Finocchietto PV, Camino AM, Aquino JB, Avagnina A, et al. The pan-caspase inhibitor Emricasan (IDN-6556) decreases liver injury and fibrosis in a murine model of non-alcoholic steatohepatitis. Liver Int 2015;35:953-66.
[171] Shiffman M, Freilich B, Vuppalanchi R, Watt K, Chan JL, Spada A, et al. Randomised clinical trial: emricasan versus placebo significantly decreases ALT and caspase 3/7 activation in subjects with non-alcoholic fatty liver disease. Aliment Pharmacol Ther 2019;49:64-73.
[172] Harrison SA, Goodman Z, Jabbar A, Vemulapalli R, Younes ZH, Freilich B, et al. A randomized, placebo-controlled trial of emricasan in patients with NASH and F1-F3 fibrosis. J Hepatol 2019; https://doi.org/10.1016/j.jhep.2019.11.024.
[173] Garcia-Tsao G, Bosch J, Kayali Z, Harrison SA, Abdelmalek MF, Lawitz E, et al. Randomized Placebo-Controlled Trial of Emricasan in Non-alcoholic Steatohepatitis (NASH) Cirrhosis with Severe Portal Hypertension. J Hepatol 2019; https://doi.org/10.1016/j.jhep.2019.12.010.
[174] Wada T, Miyashita Y, Sasaki M, Aruga Y, Nakamura Y, Ishii Y, et al. Eplerenone ameliorates the phenotypes of metabolic syndrome with NASH in liver-specific SREBP-1c Tg mice fed high-fat and high-fructose diet. Am J Physiol Endocrinol Metab 2013;305:E1415-25.
[175] Pizarro M, Solis N, Quintero P, Barrera F, Cabrera D, Rojas-de Santiago P, et al. Beneficial effects of mineralocorticoid receptor blockade in experimental non-alcoholic steatohepatitis. Liver Int 2015;35:2129-38.
[176] Polyzos SA, Kountouras J, Mantzoros CS. Leptin in nonalcoholic fatty liver disease: A narrative review. Metabolism 2015;64:60-78.
[177] Polyzos SA, Aronis KN, Kountouras J, Raptis DD, Vasiloglou MF, Mantzoros CS. Circulating leptin in non-alcoholic fatty liver disease: a systematic review and meta-analysis. Diabetologia 2015;59:30-43.
[178] Polyzos SA, Toulis KA, Goulis DG, Zavos C, Kountouras J. Serum total adiponectin in nonalcoholic fatty liver disease: a systematic review and meta-analysis. Metabolism 2011;60:313-26.
[179] Polyzos SA, Perakakis N, Mantzoros CS. Fatty liver in lipodystrophy: A review with a focus on therapeutic perspectives of adiponectin and/or leptin replacement. Metabolism 2019;96:66-82.
[180] Polyzos SA, Kountouras J, Zavos C, Deretzi G. The Potential Adverse Role of Leptin Resistance in Nonalcoholic Fatty Liver Disease: A Hypothesis Based on Critical Review of Literature. J Clin Gastroenterol 2011;45:50-4.
[181] Moon HS, Dalamaga M, Kim SY, Polyzos SA, Hamnvik OP, Magkos F, et al. Leptin’s role in lipodystrophic and nonlipodystrophic insulin-resistant and diabetic individuals. Endocr Rev 2013;34:377-412.
[182] Xu A, Wang Y, Keshaw H, Xu LY, Lam KS, Cooper GJ. The fat-derived hormone adiponectin alleviates alcoholic and nonalcoholic fatty liver diseases in mice. J Clin Invest 2003;112:91-100.
[183] Fukushima J, Kamada Y, Matsumoto H, Yoshida Y, Ezaki H, Takemura T, et al. Adiponectin prevents progression of steatohepatitis in mice by regulating oxidative stress and Kupffer cell phenotype polarization. Hepatol Res 2009;39:724-38.
[184] Polyzos SA, Kountouras J, Zavos C. Adiponectin as a potential therapeutic agent for nonalcoholic steatohepatitis. Hepatol Res 2010;40:446-7.
[185] Polyzos SA, Kountouras J, Zavos C. Adiponectin in non-alcoholic fatty liver disease treatment: therapeutic perspectives and unresolved dilemmas. Int J Clin Pract 2011;65:373-4.
[186] Ahmad A, Ali T, Kim MW, Khan A, Jo MH, Rehman SU, et al. Adiponectin homolog novel osmotin protects obesity/diabetes-induced NAFLD by upregulating AdipoRs/PPARalpha signaling in ob/ob and db/db transgenic mouse models. Metabolism 2019;90:31-43.
[187] Boutari C, Mantzoros CS. Adiponectin and leptin in the diagnosis and therapy of NAFLD. Metabolism 2020;103:154028.
[188] Kim YS, Lee SH, Park SG, Won BY, Chun H, Cho DY, et al. Low levels of total and high-molecular-weight adiponectin may predict non-alcoholic fatty liver in Korean adults. Metabolism 2020;103:154026.
[189] Sumida Y, Okanoue T, Nakajima A. Phase 3 drug pipelines in the treatment of non- alcoholic steatohepatitis. Hepatol Res 2019;49:1256-62.
[190] Eslam M, Alvani R, Shiha G. Obeticholic acid: towards first approval for NASH. Lancet 2019;394:2131-3.
[191] Iogna Prat L, Tsochatzis EA. The effect of antidiabetic medications on non-alcoholic fatty liver disease (NAFLD). Hormones (Athens) 2018;17:219-29.
[192] Gao X, Zhu Y, Wen Y, Liu G, Wan C. Efficacy of probiotics in non-alcoholic fatty liver disease in adult and children: A meta-analysis of randomized controlled trials. Hepatol Res 2016;46:1226-33.
[193] Scorletti E, Afolabi PR, Miles EA, Smith DE, Almehmadi A, Alshathry A, et al. Synbiotic Alters Fecal Microbiomes, but not Liver Fat or Fibrosis, in a Randomized Trial of Patients With Elafibranor Non-alcoholic Fatty Liver Disease. Gastroenterology 2020; https://doi.org/10.1053/j.gastro.2020.01.031.
[194] Polyzos SA, Kountouras J, Anastasiadis S, Doulberis M, Katsinelos P. Nonalcoholic fatty liver disease: Is it time for combination treatment and a diabetes-like approach? Hepatology 2018;68:389.