Fasiglifam (TAK-875) Alters Bile Acid Homeostasis in Rats and Dogs: A Potential Cause of Drug Induced Liver Injury

First-in-human study of CPL207280, a novel G-protein-coupled receptor 40/free fatty acid receptor 1 agonist, in healthy volunteers after single and multiple administration

AIM

To assess the safety, tolerability and pharmacokinetic (PK) profile of single and multiple doses of CPL207280, a new G-protein-coupled receptor 40 agonist developed to treat type 2 diabetes (T2D).

METHODS

The phase 1 study in healthy volunteers (White, age 18-55 years, body mass index 18.5-29.9 kg/m2 ) was performed after single (24 subjects, 5-480 mg) and multiple (32 subjects, 60-480 mg) once-daily administration of CPL207280.  The effect of food intake and interaction with metformin were evaluated in additional cohort (12 subjects, 120 mg). The primary objective was the safety and tolerability of CPL207280. Secondary objectives included PK and pharmacodynamic (PD) characteristics (glucose, insulin, C-peptide, proinsulin, glucagon levels) observed during the 14-day treatment period.

RESULTS

No deaths or serious adverse events (AEs) were reported. All reported AEs were classified as unrelated to the study product. No clinically significant differences in safety parameters were observed between cohorts and no food or metformin effect on safety parameters was identified. The ascending dose of CPL207280 caused an increase in the PK parameters maximum observed plasma concentration (Cmax ) or area under the plasma concentration-time curve up to 24 h. However, dose-normalized Cmax decreased with ascending dose. There was no relationship between the CPL207280 dose or prandial state and terminal elimination half-life and terminal elimination rate constant. No clear relationship between CPL207280 dose and PD area under the effect curve values was observed.

CONCLUSIONS

CPL207280 was found to be safe and well tolerated by healthy volunteers (with a low risk of hepatotoxicity) for up to 14 days of administration. The PK profile of CPL207280 supports single-daily administration and justifies further development of this therapy for patients with T2D.

Investigation of the Pharmacokinetics and Metabolic Fate of Fasiglifam (TAK-875) in Male and Female Rats Following Oral and Intravenous Administration

The metabolism and pharmacokinetics of fasiglifam (TAK-875, 2-[(3S)-6-[[3-[2,6-dimethyl-4-(3-methylsulfonylpropoxy)phenyl]phenyl]methoxy]-2,3-dihydro-1-benzofuran-3-yl]acetic acid), a selective free fatty acid receptor 1 (FFAR1)/GPR40 agonist, were studied following intravenous (5 mg/kg) and oral administration (10 and 50 mg/kg) to male and female Sprague Dawley rats.Following intravenous dosing at 5 mg/kg, peak observed plasma concentrations of 8.8/9.2 μg/ml were seen in male and female rats respectively.Following oral dosing, peak plasma concentrations at 1 h of ca. 12.4/12.9 μg/ml for 10 mg/kg and 76.2/83.7 μg/ml for 50 mg/kg doses were obtained for male and female rats respectively. Drug concentrations then declined in the plasma of both sexes with t_1/2's of 12.4 (male) and 11.2 h (female). Oral bioavailability was estimated to be 85-120% in males and females at both dose levels.Urinary excretion was low, but in a significant sex-related difference, female rats eliminated ca. 10-fold more drug-related material by this route.Fasiglifam was the principal drug-related compound in plasma, with 15 metabolites, including the acyl glucuronide, also detected. In addition to previously identified metabolites, a novel biotransformation, that produced a side-chain shortened metabolite via elimination of CH₂ from the acetyl side chain was noted with implications for drug toxicity.

Prospect of in vitro Bile Fluids Collection in Improving Cell-Based Assay of Liver Function

The liver plays a pivotal role in the clearance of drugs. Reliable assays for liver function are crucial for various metabolism investigation, including toxicity, disease, and pre-clinical testing for drug development. Bile is an aqueous secretion of a functioning liver. Analyses of bile are used to explain drug clearance and related effects and are thus important for toxicology and pharmacokinetic research. Bile fluids collection is extensively performed in vivo, whereas this process is rarely reproduced as in the in vitro studies. The key to success is the technology involved, which needs to satisfy multiple criteria. To ensure the accuracy of subsequent chemical analyses, certain amounts of bile are needed. Additionally, non-invasive and continuous collections are preferable in view of cell culture. In this review, we summarize recent progress and limitations in the field. We highlight attempts to develop advanced liver cultures for bile fluids collection, including methods to stimulate the secretion of bile in vitro. With these strategies, researchers have used a variety of cell sources, extracellular matrix proteins, and growth factors to investigate different cell-culture environments, including three-dimensional spheroids, cocultures, and microfluidic devices. Effective combinations of expertise and technology have the potential to overcome these obstacles to achieve reliable in vitro bile assay systems.

The Role of Uptake and Efflux Transporters in the Disposition of Glucuronide and Sulfate Conjugates

Glucuronidation and sulfation are the most typical phase II metabolic reactions of drugs. The resulting glucuronide and sulfate conjugates are generally considered inactive and safe. They may, however, be the most prominent drug-related material in the circulation and excreta of humans. The glucuronide and sulfate metabolites of drugs typically have limited cell membrane permeability and subsequently, their distribution and excretion from the human body requires transport proteins. Uptake transporters, such as organic anion transporters (OATs and OATPs), mediate the uptake of conjugates into the liver and kidney, while efflux transporters, such as multidrug resistance proteins (MRPs) and breast cancer resistance protein (BCRP), mediate expulsion of conjugates into bile, urine and the intestinal lumen. Understanding the active transport of conjugated drug metabolites is important for predicting the fate of a drug in the body and its safety and efficacy. The aim of this review is to compile the understanding of transporter-mediated disposition of phase II conjugates. We review the literature on hepatic, intestinal and renal uptake transporters participating in the transport of glucuronide and sulfate metabolites of drugs, other xenobiotics and endobiotics. In addition, we provide an update on the involvement of efflux transporters in the disposition of glucuronide and sulfate metabolites. Finally, we discuss the interplay between uptake and efflux transport in the intestine, liver and kidneys as well as the role of transporters in glucuronide and sulfate conjugate toxicity, drug interactions, pharmacogenetics and species differences.

Evaluation of the hepatotoxicity of the novel GPR40 (FFAR1) agonist CPL207280 in the rat and monkey

GPR40 (FFAR1) is a promising target for the managing type 2 diabetes (T2D). The most advanced GPR40 agonist TAK-875 exhibited satisfactory glucose-lowering effects in phase II and III studies. However, the phase III studies of TAK-875 revealed drug-induced liver injury (DILI). It is unknown whether DILI is a consequence of a specific GPR40 agonist or is an inherent feature of all GPR40 agonists. CPL207280 is a novel GPR40 agonist that improves diabetes in Zucker Diabetic Fatty (ZDF) rats, Goto Kakizaki (GK) rats and db/db mice. In this report, the DILI-related toxicity of CPL207280 was compared directly with that of TAK-875. In vitro studies evaluating hepatic biliary transporter inhibition, mitochondrial function, and metabolic profiling were performed in hepatocytes from different species. The long term toxicity of CPL207280 was studied in vivo in rats and monkeys. Activity of CPL207280 was one order of magnitude lesser than that of TAK-875 for the inhibition of bile acid transporters. CPL207280 had a negligible effect on the hepatic mitochondria. In contrast to TAK-875, which was metabolized through toxic glucuronidation, CPL207280 was metabolized mainly through oxidation. No deleterious hepatic effects were observed in chronically treated healthy and diabetic animals. The study presents promising data on the feasibility of creating a liver-safe GPR40 agonist. Additionally, it can be concluded that DILI is not a hallmark of GPR40 agonists; it is linked to the intrinsic properties of an individual agonist.

GPR40 receptor agonist TAK-875 improves cognitive deficits and reduces β-amyloid production in APPswe/PS1dE9 mice

RATIONALE

Alzheimer's disease (AD) is an age-related neurodegenerative disease characterized by progressive cognitive dysfunction and memory impairment. G protein-coupled receptor 40 (GPR40) is expressed in brain in addition to periphery and is associated with cognitive function such as space orientation, memory, and learning. However, the effects and mechanisms of GPR40 agonist in improving the AD progression remain largely unknown.

OBJECTIVES

The present study aimed to investigate the therapeutic effects and mechanisms of a potent and selective GPR40 agonist TAK-875 on the APPswe/PS1dE9 mice.

RESULTS

The results showed that intracerebroventricular administration of TAK-875 significantly rescued cognitive deficits in APPswe/PS1dE9 mice, and these effects may be mediated by the regulation of phospholipase C/protein kinase C signaling pathway, which enhanced α-secretase ADAM10 activity, promoted amyloid precursor protein non-amyloidogenic processing pathway, and reduced β-amyloid production.

CONCLUSIONS

These results suggest that GPR40 may be a potential therapeutic target for AD, and GPR40 agonists may become promising AD drugs in the future.

Novel therapies with precision mechanisms for type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is one of the greatest health crises of our time and its prevalence is projected to increase by >50% globally by 2045. Currently, 10 classes of drugs are approved by the US Food and Drug Administration for the treatment of T2DM. Drugs in development for T2DM must show meaningful reductions in glycaemic parameters as well as cardiovascular safety. Results from an increasing number of cardiovascular outcome trials using modern T2DM therapeutics have shown a reduced risk of atherosclerotic cardiovascular disease, congestive heart failure and chronic kidney disease. Hence, guidelines have become increasingly evidence based and more patient centred, focusing on reaching individualized glycaemic goals while optimizing safety, non-glycaemic benefits and the prevention of complications. The bar has been raised for novel therapies under development for T2DM as they are now expected to achieve these aims and possibly even treat concurrent comorbidities. Indeed, the pharmaceutical pipeline for T2DM is fertile. Drugs that augment insulin sensitivity, stimulate insulin secretion or the incretin axis, or suppress hepatic glucose production are active in more than 7,000 global trials using new mechanisms of action. Our collective goal of being able to truly personalize medicine for T2DM has never been closer at hand.

Targeting lipid GPCRs to treat type 2 diabetes mellitus - progress and challenges

Therapeutic approaches to the treatment of type 2 diabetes mellitus that are designed to increase insulin secretion either directly target β-cells or indirectly target gastrointestinal enteroendocrine cells (EECs), which release hormones that modulate insulin secretion (for example, incretins). Given that β-cells and EECs both express a large array of G protein-coupled receptors (GPCRs) that modulate insulin secretion, considerable research and development efforts have been undertaken to design therapeutic drugs targeting these GPCRs. Among them are GPCRs specific for free fatty acid ligands (lipid GPCRs), including free fatty acid receptor 1 (FFA1, otherwise known as GPR40), FFA2 (GPR43), FFA3 (GPR41) and FFA4 (GPR120), as well as the lipid metabolite binding glucose-dependent insulinotropic receptor (GPR119). These lipid GPCRs have demonstrated important roles in the control of islet and gut hormone secretion. Advances in lipid GPCR pharmacology have led to the identification of a number of synthetic agonists that exert beneficial effects on glucose homeostasis in preclinical studies. Yet, translation of these promising results to the clinic has so far been disappointing. In this Review, we present the physiological roles, pharmacology and clinical studies of these lipid receptors and discuss the challenges associated with their clinical development for the treatment of type 2 diabetes mellitus.

In vitro assessment of farnesoid X receptor antagonism to predict drug-induced liver injury risk

Drug-induced liver injury (DILI) continues to be a major cause of drug attrition and restrictive labeling. Given the importance of farnesoid X receptor (FXR) in bile acid homeostasis, drug-related FXR antagonism may be an important mechanism of DILI. However, a comprehensive assessment of this phenomenon broadly in the context of DILI is lacking. As such, we used an orthogonal approach comprising a FXR target gene assay in primary human hepatocytes and a commercially available FXR reporter assay to investigate the potential FXR antagonistic effects of an extensive test set of 159 compounds with and without association with clinical DILI. Data were omitted from analysis based on the presence of cytotoxicity to minimize false positive assay signals and other complications in data interpretation. Based on the experimental approaches employed and corresponding data, the prevalence of FXR antagonism was relatively low across this broad DILI test set, with 16-24% prevalence based on individual assay results or combined signals in both assays. Moreover, FXR antagonism was not highly predictive for identifying clinically relevant hepatotoxicants retrospectively, where FXR antagonist classification alone had minimal to moderate predictive value as represented by positive and negative likelihood ratios of 2.24-3.84 and 0.72-0.85, respectively. The predictivity did not increase significantly when considering only compounds with high clinical exposure (maximal or efficacious plasma exposures > 1.0 μM). In contrast, modest gains in predictive value of FXR antagonism were observed considering compounds that also inhibit bile salt export pump. In addition, we have identified novel FXR antagonistic effects of well-studied hepatotoxic drugs, including bosentan, tolcapone and ritonavir. In conclusion, this work represents a comprehensive evaluation of FXR antagonism in the context of DILI, including its overall predictivity and challenges associated with detecting this phenomenon in vitro.

Quantitative Systems Toxicology Analysis of In Vitro Mechanistic Assays Reveals Importance of Bile Acid Accumulation and Mitochondrial Dysfunction in TAK-875-Induced Liver Injury

TAK-875 (fasiglifam), a GPR40 agonist in development for the treatment of type 2 diabetes (T2D), was voluntarily terminated in Phase III trials due to adverse liver effects. The potential mechanisms of TAK-875 toxicity were explored by combining in vitro experiments with quantitative systems toxicology (QST) using DILIsym, a mathematical representation of drug-induced liver injury. In vitro assays revealed that bile acid transporters were inhibited by both TAK-875 and its metabolite, TAK-875-Glu. Experimental data indicated that human bile salt export pump (BSEP) inhibition by TAK-875 was mixed whereas sodium taurocholate co-transporting polypeptide (NTCP) inhibition by TAK-875 was competitive. Furthermore, experimental data demonstrated that both TAK-875 and TAK-875-Glu inhibit mitochondrial electron transport chain (ETC) enzymes. These mechanistic data were combined with a physiologically based pharmacokinetic (PBPK) model constructed within DILIsym to estimate liver exposure of TAK-875 and TAK-875-Glu. In a simulated population (SimPops) constructed to reflect T2D patients, 16/245 (6.5%) simulated individuals developed alanine aminotransferase (ALT) elevations, an incidence similar to that observed with 200 mg daily dosing in clinical trials. Determining the mode of bile acid transporter inhibition (K_i) was critical to accurate predictions. In addition, simulations conducted on a sensitive subset of individuals (SimCohorts) revealed that when either BSEP or ETC inhibition was inactive, ALT elevations were not predicted to occur, suggesting that the two mechanisms operate synergistically to produce the observed clinical response. These results demonstrate how utilizing QST methods to interpret in vitro experimental results can lead to an improved understanding of the clinically relevant mechanisms underlying drug-induced toxicity.

Roles of Hepatic Drug Transporters in Drug Disposition and Liver Toxicity

Hepatic drug transporters are mainly distributed in parenchymal liver cells (hepatocytes), contributing to drug's liver disposition and elimination. According to their functions, hepatic transporters can be roughly divided into influx and efflux transporters, translocating specific molecules from blood into hepatic cytosol and mediating the excretion of drugs and metabolites from hepatic cytosol to blood or bile, respectively. The function of hepatic transport systems can be affected by interspecies differences and inter-individual variability (polymorphism). In addition, some drugs and disease can redistribute transporters from the cell surface to the intracellular compartments, leading to the changes in the expression and function of transporters. Hepatic drug transporters have been associated with the hepatic toxicity of drugs. Gene polymorphism of transporters and altered transporter expressions and functions due to diseases are found to be susceptible factors for drug-induced liver injury (DILI). In this chapter, the localization of hepatic drug transporters, their regulatory factors, physiological roles, and their roles in drug's liver disposition and DILI are reviewed.

Designing around Structural Alerts in Drug Discovery

Cumulative research over several decades has implicated the involvement of reactive metabolites in many idiosyncratic adverse drug reactions (IADRs). Consequently, "avoidance" strategies have been inserted into drug discovery paradigms, which include the exclusion of structural alerts and possible termination of reactive metabolite-positive compounds. Several noteworthy examples where reactive metabolite-related liabilities have been resolved through structure-metabolism studies are presented herein. Considerable progress has also been made in addressing the limitations of the avoidance strategy and further refining the process of managing reactive metabolite issues in drug development. These efforts primarily stemmed from the observation that numerous drugs, which contain structural alerts and/or form reactive metabolites, are devoid of ADRs. The Perspective also dwells into an analysis of the structural alert/reactive metabolite concept with a discussion of risk mitigation tactics to support the progression of reactive metabolite-positive drug candidates.

Phase I study of PF‐04895162, a Kv7 channel opener, reveals unexpected hepatotoxicity in healthy subjects, but not rats or monkeys: clinical evidence of disrupted bile acid homeostasis

During a randomized Phase 1 clinical trial the drug candidate, PF‐04895162 (ICA‐105665), caused transaminase elevations (≥grade 1) in six of eight healthy subjects treated at 300 mg twice daily for 2‐weeks (NCT01691274). This was unexpected since studies in rats (<6 months) and cynomolgus monkeys (<9 months) treated up to 100 mg/kg/day did not identify the liver as a target organ. Mechanistic studies showed PF‐04895162 had low cytotoxic potential in human hepatocytes, but inhibited liver mitochondrial function and bile salt export protein (BSEP) transport. Clinical relevance of these postulated mechanisms of liver injury was explored in three treated subjects that consented to analysis of residual pharmacokinetic plasma samples. Compared to a nonresponder, two subjects with transaminase elevations displayed higher levels of miRNA122 and total/conjugated bile acid species, whereas one demonstrated impaired postprandial clearance of systemic bile acids. Elevated taurine and glycine conjugated to unconjugated bile acid ratios were observed in two subjects, one before the onset of elevated transaminases. Based on the affinity of conjugated bile acid species for transport by BSEP, the profile of plasma conjugated/unconjugated bile acid species was consistent with inhibition of BSEP. These data collectively suggest that the human liver injury by PF‐04895162 was due to alterations in bile acid handling driven by dual BSEP/mitochondrial inhibition, two important risk factors associated with drug‐induced liver injury in humans. Alterations in systemic bile acid composition were more important than total bile acids in the manifestation of clinical liver injury and may be a very early biomarker of BSEP inhibition.

Liver Safety of Fasiglifam (TAK-875) in Patients with Type 2 Diabetes: Review of the Global Clinical Trial Experience

INTRODUCTION

Fasiglifam (TAK-875) is a G protein-coupled receptor 40 agonist that was being investigated for treatment of type 2 diabetes mellitus (T2DM). A development program was terminated late in phase III clinical trials due to liver safety concerns.

METHODS

The liver safety of fasiglifam was assessed from data based on six phase II and nine phase III double-blind studies and two open-label studies with emphasis on pooled data from 15 double-blind studies from both global and Japanese development programs. Taking into consideration different daily doses of fasiglifam administered in clinical studies, the primary comparisons were between all patients exposed to fasiglifam (any dose) versus placebo, and, where applicable, versus the two active comparators, sitagliptin or glimepiride. A Liver Safety Evaluation Committee consisting of hepatologists blinded to treatment assignments evaluated hepatic adverse events (AEs) and serious AEs (SAEs) for causal relationship to study drug.

RESULTS

The analysis included data from 9139 patients with T2DM in 15 double-blind controlled studies who received either fasiglifam (n = 5359, fasiglifam group), fasiglifam and sitagliptin (n = 123), or a comparator agent (n = 3657, non-exposed group consisting of placebo and other antidiabetic agents). Exposure to treatment for more than 1 year ranged from 249 patients in the placebo arm, to 370 patients in the glimepiride arm and 617 patients in the fasiglifam 50 mg arm. The primary focus of the analysis was on the hepatic safety of fasiglifam. The overall safety profile based on treatment-emergent AEs (TEAEs), SAEs, deaths, and withdrawal due to AEs was similar between fasiglifam and placebo (excluding liver test abnormalities). However, there was an increased incidence rate of serum alanine aminotransferase (ALT) elevations > 3 × upper limit of normal (ULN), 5 × ULN, and 10 × ULN in fasiglifam-treated patients compared with those treated with placebo or active comparators. ALT elevations > 3 × ULN for fasiglifam were 2.7% compared with 0.8 and 0.5% for the active comparators and placebo. There did not appear to be a clear dose response in incidence of ALT elevations between patients receiving 25 or 50 mg daily. The cumulative incidence of elevations in serum ALT > 3 × ULN was higher in the first 6 months of treatment with fasiglifam compared with both placebo and the active comparators, but the rate of new ALT elevations appeared to be similar across all treatment groups thereafter. No demographic or baseline patient characteristics were identified to predict elevations exceeding ALT > 3 × ULN in fasiglifam-treated patients. The pattern of liver injury with fasiglifam was hepatocellular, and there were no reports of liver-related deaths, liver failure or life-threatening liver injury. Most fasiglifam-associated ALT elevations were asymptomatic and resolved promptly upon discontinuing treatment, but in two patients the recovery was prolonged. Importantly, three important serious liver injury cases were identified among fasiglifam-treated patients; one case was adjudicated to be a clear Hy's Law case and the two remaining cases were considered to closely approximate Hy's Law cases.

CONCLUSIONS

Although the incidence of overall AEs, SAEs, and deaths was similar between fasiglifam and placebo, a liver signal was identified based primarily on the difference in liver chemistry values in the fasiglifam group compared with the placebo and active comparator groups. Three serious liver injuries were attributed to fasiglifam treatment. Clinical development of fasiglifam was halted due to these liver safety concerns.

Quantitative translational modeling to facilitate preclinical to clinical efficacy & toxicity translation in oncology

Significant scientific advances in biomedical research have expanded our knowledge of the molecular basis of carcinogenesis, mechanisms of cancer growth, and the importance of the cancer immunity cycle. However, despite scientific advances in the understanding of cancer biology, the success rate of oncology drug development remains the lowest among all therapeutic areas. In this review, some of the key translational drug development objectives in oncology will be outlined. The literature evidence of how mathematical modeling could be used to build a unifying framework to answer these questions will be summarized with recommendations on the strategies for building such a mathematical framework to facilitate the prediction of clinical efficacy and toxicity of investigational antineoplastic agents. Together, the literature evidence suggests that a rigorous and unifying preclinical to clinical translational framework based on mathematical models is extremely valuable for making go/no-go decisions in preclinical development, and for planning early clinical studies.

Evaluation of the Pharmacokinetics and Safety of a Single Oral Dose of Fasiglifam in Subjects with Mild or Moderate Hepatic Impairment

BACKGROUND AND AIMS

Fasiglifam, a potent, selective novel agonist of G protein-coupled receptor 40, stimulates insulin secretion at elevated blood glucose levels in a glucose-dependent manner. This study evaluated the potential effect of hepatic impairment on the pharmacokinetics and safety of a single dose of fasiglifam and its metabolite M-I. Fasiglifam's clinical development was halted due to liver safety concerns.

METHODS

In this phase I, open-label study, subjects with mild or moderate hepatic impairment, along with matched controls (gender, weight, age, and smoking status), received a single, 25-mg oral dose of fasiglifam. Blood samples were collected through 336 h post-dose for pharmacokinetic evaluation.

RESULTS

Overall, 73% of subjects were male with a mean age of 54 years. Compared with normal hepatic function subjects (n = 14), mean systemic fasiglifam exposure (C_max and AUC_∞) was reduced in mild (n = 8) and moderate (n = 8) hepatic impairment subjects by approximately 20-40%. However, the observed percent unbound drug plasma concentration appeared comparable across all groups. Mean oral clearance was higher and terminal half-life lower in subjects with mild or moderate hepatic impairment compared with normal hepatic function subjects. Fasiglifam M-I systemic exposure increased by approximately twofold in subjects with mild or moderate hepatic impairment compared with those with normal hepatic function. Fasiglifam was well tolerated, and there were no reports of hypoglycemia.

CONCLUSION

Hepatic status did not significantly impact systemic exposure of fasiglifam in this study, in fact, a decrease was observed, suggesting no dose reduction would be required for patients with hepatic impairment.

Dissecting the Physiology and Pathophysiology of Glucagon-Like Peptide-1

An aging world population exposed to a sedentary life style is currently plagued by chronic metabolic diseases, such as type-2 diabetes, that are spreading worldwide at an unprecedented rate. One of the most promising pharmacological approaches for the management of type 2 diabetes takes advantage of the peptide hormone glucagon-like peptide-1 (GLP-1) under the form of protease resistant mimetics, and DPP-IV inhibitors. Despite the improved quality of life, long-term treatments with these new classes of drugs are riddled with serious and life-threatening side-effects, with no overall cure of the disease. New evidence is shedding more light over the complex physiology of GLP-1 in health and metabolic diseases. Herein, we discuss the most recent advancements in the biology of gut receptors known to induce the secretion of GLP-1, to bridge the multiple gaps into our understanding of its physiology and pathology.

SAR Studies of Indole-5-propanoic Acid Derivatives To Develop Novel GPR40 Agonists

G-protein coupled receptor 40 (GPR40) has been considered to be an attractive drug target for the treatment of type 2 diabetes because of its role in free fatty acids-mediated enhancement of glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. A series of indole-5-propanoic acid compounds were synthesized, and their GPR40 agonistic activities were evaluated by nuclear factor of activated T-cells reporter assay and GSIS assay in the MIN-6 insulinoma cells. Three compounds, 8h (EC₅₀ = 58.6 nM), 8i (EC₅₀ = 37.8 nM), and 8o (EC₅₀ = 9.4 nM), were identified as potent GPR40 agonists with good GSIS effects.

FFA4/GPR120: Pharmacology and Therapeutic Opportunities

Free Fatty Acid receptor 4 (FFA4), also known as GPR120, is a G-protein-coupled receptor (GPCR) responsive to long-chain fatty acids that is attracting considerable attention as a potential novel therapeutic target for the treatment of type 2 diabetes mellitus (T2DM). Although no clinical studies have yet been initiated to assess efficacy in this indication, a significant number of primary publications and patents have highlighted the ability of agonists with potency at FFA4 to improve glucose disposition and enhance insulin sensitivity in animal models. However, the distribution pattern of the receptor suggests that targeting FFA4 may also be useful in other conditions, ranging from cancer to lung function. Here, we discuss and contextualise the basis for these ideas and the results to support these conclusions.

Substantial focus on the therapeutic potential of FFA4/GPR120 is currently directed towards type 2 diabetes.

Progress in the identification and characterisation of FFA4/GPR120 agonist ligands is apparent in both the primary scientific and patent literatures.

In models of glucose handling, FFA4/GPR120 agonists appear highly effective.

Recent indications provide support for consideration of FFA4/GPR120 ligands in areas of cancer treatment.

High levels of expression of FFA4/GPR120 in the lung suggest utility in analysis of the potential therapeutic roles of FFA4/GPR120 ligands in both acute and chronic airway inflammatory conditions.

Utility of spherical human liver microtissues for prediction of clinical drug-induced liver injury

Drug-induced liver injury (DILI) continues to be a major source of clinical attrition, precautionary warnings, and post-market withdrawal of drugs. Accordingly, there is a need for more predictive tools to assess hepatotoxicity risk in drug discovery. Three-dimensional (3D) spheroid hepatic cultures have emerged as promising tools to assess mechanisms of hepatotoxicity, as they demonstrate enhanced liver phenotype, metabolic activity, and stability in culture not attainable with conventional two-dimensional hepatic models. Increased sensitivity of these models to drug-induced cytotoxicity has been demonstrated with relatively small panels of hepatotoxicants. However, a comprehensive evaluation of these models is lacking. Here, the predictive value of 3D human liver microtissues (hLiMT) to identify known hepatotoxicants using a panel of 110 drugs with and without clinical DILI has been assessed in comparison to plated two-dimensional primary human hepatocytes (PHH). Compounds were treated long-term (14 days) in hLiMT and acutely (2 days) in PHH to assess drug-induced cytotoxicity over an 8-point concentration range to generate IC₅₀ values. Regardless of comparing IC₅₀ values or exposure-corrected margin of safety values, hLiMT demonstrated increased sensitivity in identifying known hepatotoxicants than PHH, while specificity was consistent across both assays. In addition, hLiMT out performed PHH in correctly classifying hepatotoxicants from different pharmacological classes of molecules. The hLiMT demonstrated sufficient capability to warrant exploratory liver injury biomarker investigation (miR-122, HMGB1, α-GST) in the cell-culture media. Taken together, this study represents the most comprehensive evaluation of 3D spheroid hepatic cultures up to now and supports their utility for hepatotoxicity risk assessment in drug discovery.