Therapeutic Potential of Aleglitazar,a New Dual PPAR-α/γ Agonist

Preventing morbidity and mortality from diabetes mellitus is of paramount importance as the incidence of this disease is increasing across the world. While microvascular complications of diabetes such as nephropathy, retinopathy, and neuropathy are reduced with intensive glycemic control, treatment of hyperglycemia has not been consistently shown to have effects on the macrovascular complications of diabetes such as coronary artery, cerebrovascular, and peripheral vascular disease. Preventive efforts have accordingly shifted toward the modification of other cardiovascular risk factors in diabetic patients. Agonism of the peroxisome proliferator-activated receptors (PPARs) has long been an attractive target for antidiabetic therapy due to the role of PPARs in glycemic control and lipid metabolism. PPAR-γ agonists such as rosiglitazone and pioglitazone are used in clinical practice for the treatment of diabetes, and there is some evidence that pioglitazone may have positive effects on cardiovascular complications by virtue of its favorable effects on lipid profiles. However, they have not been shown to reduce macrovascular events. PPAR-α agonism is the mechanism of action in the fibrate class of medications; these agents have been shown to increase high-density lipoprotein cholesterol (HDL-C) levels, reduce triglyceride levels, and improve cardiovascular outcomes. Given the prevalence of lipid abnormalities in patients with diabetes, dual PPAR-α/γ agonists (glitazars) could potentially benefit patients with diabetes. A phase II trial examining a novel dual PPAR agonist, aleglitazar, showed that therapy with this agent reduced hyperglycemia and favorably modified levels of HDL-C and triglycerides with an acceptable safety profile. Aleglitazar is currently being studied in large-scale clinical trials to assess whether it will reduce the risk of major cardiovascular endpoints (death, myocardial infarction, or stroke) among patients with diabetes and coronary artery disease. If ongoing studies confirm the theoretical benefit and safety of dual PPAR-α/γ agonism, aleglitazar may become the first therapy demonstrated to reduce macrovascular complications in patients with diabetes.     

Aleglitazar, a dual PPARα and PPARγ agonist for the potential oral treatment of type 2 diabetes mellitus

PPARγ and PPARα are nuclear receptors mainly involved in the regulation of glucose homeostasis and lipid levels, respectively. Aleglitazar, being developed by Roche Holding, is a dual agonist for PPARγ and PPARα for the potential simultaneous treatment of hyperglycemia and dyslipidemia in patients with type 2 diabetes mellitus (T2DM). In preclinical studies, aleglitazar decreased non-fasted glucose levels, increased glucose clearance and improved insulin resistance, while also increasing HDL-cholesterol and decreasing LDL-cholesterol levels in serum. In phase I and II clinical trials in patients with T2DM, aleglitazar demonstrated beneficial antidiabetic activities and had a higher antihyperglycemic efficacy than pioglitazone (a PPARγ agonist). Aleglitazar improved the lipid profile in patients and decreased levels of cardiovascular markers of inflammation and clotting. The observed adverse events were characteristic of either PPARγ or PPARα agonists; however, when compared to pioglitazone-PPARγ-mediated effects, such as edema and weight gain, these were less severe. PPARγ-mediated adverse events on bone have not been measured and should be addressed in the future. The PPARα-mediated adverse effects on renal function are of concern and are a primary endpoint of ongoing phase II clinical trials in patients with T2DM. A phase III clinical trial was also ongoing in patients with T2DM who had recently experienced a cardiac event.     

No evidence of QT prolongation with supratherapeutic doses of aleglitazar

Aleglitazar is a dual peroxisome proliferator-activated receptor (PPAR)-α/γ agonist in clinical development, designed to offer a balanced activation of PPAR-α and PPAR-γ. A phase 2 trial has demonstrated improvements in dyslipidemia and glycemic control and reduction of cardiovascular risk markers in patients with type 2 diabetes mellitus treated with aleglitazar. This study evaluated whether supratherapeutic doses of aleglitazar affect cardiac repolarization, as detected by changes in the QT interval.Healthy subjects were randomized to receive single oral doses of placebo, 300 μg aleglitazar, 3000 μg aleglitazar, and 400 mg moxifloxacin, in 1 of 4 sequences. Triplicate 12-lead electrocardiogram measurements were recorded predose and regularly (0.75-72 hours) after each treatment. The primary outcome was measurement of QT interval using a study-specific correction factor for heart rate.Administration of aleglitazar (300 μg and 3000 μg) did not cause any significant QT prolongation and after aleglitazar treatment any mean increases from placebo were <5 msec, at all time points. There was a trend for aleglitazar to cause a small dose-dependent decrease in QT interval using a study-specific correction factor for heart rate. The incidence of adverse events was similar with aleglitazar (18%-20%) and placebo (26%).Single supratherapeutic doses of aleglitazar are not associated with prolongation of the QT interval corrected for heart rate.     

Multitargeted bioactive ligands for PPARs discovered in the last decade

Type 2 diabetes took insulin resistance as the main clinical manifestation. PPARs have been reported to be the therapeutic targets of metabolic disorders, such as obesity, hypertension, diabetes, and cardiovascular disease. Previously, PPARγ agonist rosiglitazone was restricted in clinic due to cardiomyocytes infarction, weight gain, and other serious side‐effects, which were mainly due to the single and selective PPARγ agonism. In recent years, multitarget‐directed PPAR agonists with synergistic reaction as well as fewer side‐effect have been the hot topic in designing promising agents. In this review, we updated and generalized the development of PPARγ partial agonists, PPARγ antagonists, PPARα/γ dual agonists, PPARδ partial agonists, PPARδ antagonists, PPARα/δ dual agonists, PPARγ/δ dual agonists, and PPARα/γ/δ pan‐agonists published in recent decade. Most of these molecules were modified from known structures or came from high‐throughput screening. Among these molecules, some were expected to be promising drugs against metabolic disorders, while others seemed to provide new insight for designing novel PPAR agents.     

Non-clinical safety evaluation and risk assessment to human of aleglitazar,a dual PPAR α/γ agonist,and its major human metabolite

The non-clinical safety profile of aleglitazar, a peroxisome proliferator activated receptor alpha/gamma agonist, and its major human metabolite M6 was studied in a complete package consisting of drug metabolism and pharmacokinetics characterization, safety pharmacology, genotoxicity, repeat dose toxicity, reproductive toxicity and carcinogenicity studies. These studies identified the following main targets similar to other PPAR agonists: red blood cell parameters, liver, heart, kidney, ovaries, testes, bone marrow, adipose tissue, and fluid accumulation. Additionally, and in the 12-month monkey study only, an increased incidence of generalized hair loss/thinning was observed in all groups including controls. In the rat carcinogenicity study there was no statistically significant increase in tumors. In the mouse carcinogenicity study, there was an increased incidence of angiomatous tumors and there were three males with gallbladder adenoma. No relevant compound-related effects were observed in safety pharmacology, genotoxicity, and a 28-day immunotoxicity rat study. Effects observed in reproductive toxicity studies were similar to those known for other PPARγ agonists. Separate studies with the human metabolite M6 did not reveal findings that would prevent human dosing. Overall, the results from the non-clinical safety studies conducted with aleglitazar and the human metabolite M6 were considered to support the clinical Phase 3 program.     

Peroxisome proliferator-activated receptor ligands in atherosclerosis

In this review, the effect of peroxisome proliferator-activated receptor (PPAR) ligands on atherosclerosis is examined. The PPAR-γ agonist thiazolidinediones are currently indicated for the management of Type 2 diabetes mellitus, and the PPAR-α agonist fibrates are used in dyslipidaemia. Here their mechanism of action and the pre-clinical and clinical evidence for the use of these medications for the prevention and treatment of atherosclerotic disease is explored. In addition, the role of PPAR-δ and the possibilities for the role of dual-binding agonists are examined.     

Saroglitazar for the treatment of dyslipidemia in diabetic patients

Introduction: Diabetes and dyslipidemia are commonly associated modifiable risk factors for cardiovascular diseases. Majority of patients with diabetes also suffer from dyslipidemia (diabetic dyslipidemia). Diabetic dyslipidemia is more atherogenic as it is commonly associated with high triglyceride (TG) levels, high proportion of small dense low-density lipoprotein cholesterol and low high-density lipoprotein cholesterol (HDL-C) level (atherogenic dyslipidemia). Currently used pharmacotherapies for the management of diabetes and dyslipidemia like thiazolidinediones (PPAR-γ agonist; for insulin resistance) and fibrates (PPAR-α agonist; for hypertriglyceridemia) have many limitations and side effects. Saroglitazar, a dual PPAR-α/γ agonists, is an emerging therapeutic option with its dual benefit on glycemic and lipid parameters.

Areas covered: This paper reviews the clinical development of saroglitazar for the management of diabetic dyslipidemia. The efficacy and safety profile of saroglitazar is reviewed in context to currently available therapy like pioglitazone for diabetes and fibrates for hypertriglyceridemia. In addition, this paper also reviews the association between diabetes and dyslipidemia and the role of TG in reducing cardiovascular events.

Expert opinion: Saroglitazar, a dual PPAR-α/γ agonist, is a potential therapeutic option for the management of diabetic dyslipidemia. It has dual benefit of significant improvement in glycemic parameters (glycated hemoglobin and fasting blood glucose) and significant improvement in dyslipidemia (TGs, apolipoprotein B, non-HDL-C). The results of Phase III clinical trials indicate that saroglitazar is devoid of conventional side effects of fibrates and pioglitazone. Future clinical trials of saroglitazar will further establish its place in the management of diabetes, dyslipidemia and associated cardiovascular risk.     

Early investigational drugs targeting PPAR-α for the treatment of metabolic disease

Introduction: The fibrates have been used for many years to treat dyslipidemias and have also recently been shown to have anti-inflammatory effects. They are relatively weak PPAR-α agonists and do have some adverse effects. Novel compounds are in development, which are selective PPAR modulators (SPPARMs) and have more potent PPAR-α agonist activity. These may prove to have advantages in the treatment of dyslipidemia, insulin resistance and non-alcoholic fatty liver disease (NAFLD).

Areas covered: This review focuses on PPAR-α agonists or SPPARMs in development describing the preclinical and early clinical studies. The information was obtained by searching the published literature and abstracts from recent meetings. Ongoing clinical trials were identified using the Clinicaltrial.gov database.

Expert opinion: There is still a need for new drugs to treat atherogenic dyslipidemia. The highly potent and selective PPAR-α agonist K-877 has shown beneficial effects on atherogenic dyslipidemia and absence of some adverse effects seen with fibrates. The dual PPAR-α/PPAR-δ agonist GFT-505 has shown favorable results in improving atherogenic dyslipidemia and insulin resistance and appears to be a potential candidate for the treatment of NAFLD. Long-term trials are needed to assess the safety and efficacy of these new agents for cardiovascular and liver outcomes.     

Benzimidazolones: a new class of selective peroxisome proliferator-activated receptor γ (PPARγ) modulators

A series of benzimidazolone carboxylic acids and oxazolidinediones were designed and synthesized in search of selective PPARγ modulators (SPPARγMs) as potential therapeutic agents for the treatment of type II diabetes mellitus (T2DM) with improved safety profiles relative to rosiglitazone and pioglitazone, the currently marketed PPARγ full agonist drugs. Structure-activity relationships of these potent and highly selective SPPARγMs were studied with a focus on their unique profiles as partial agonists or modulators. A variety of methods, such as X-ray crystallographic analysis, PPARγ transactivation coactivator profiling, gene expression profiling, and mutagenesis studies, were employed to reveal the differential interactions of these new analogues with PPARγ receptor in comparison to full agonists. In rodent models of T2DM, benzimidazolone analogues such as (5R)-5-(3-{[3-(5-methoxybenzisoxazol-3-yl)benzimidazol-1-yl]methyl}phenyl)-5-methyloxazolidinedione (51) demonstrated efficacy equivalent to that of rosiglitazone. Side effects, such as fluid retention and heart weight gain associated with PPARγ full agonists, were diminished with 51 in comparison to rosiglitazone based on studies in two independent animal models.     

Dual acting and pan-PPAR activators as potential anti-diabetic therapies

The thiazolidinedione PPAR-γ activator drugs rosiglitazone and pioglitazone suppress insulin resistance in type 2 diabetic patients. They lock lipids into adipose tissue triglyceride stores, thereby preventing lipid metabolites from causing insulin resistance in liver and skeletal muscle and β-cell failure. They also reduce the secretion of inflammatory cytokines such as TNFα and increase the plasma level of adiponectin, which increases insulin sensitivity in liver and skeletal muscle. However, they have only a modest effect on dyslipidaemia, and they increase fat mass and plasma volume. Fibrate PPAR-α activator drugs decrease plasma triglycerides and increase HDL-cholesterol levels. PPAR-δ activators increase the capacity for fat oxidation in skeletal muscle.Clinical experience with bezafibrate, which activates PPAR-δ and -α, and studies on the PPAR-α/δ activator tetradecylthioacetic acid, the PPAR-δ activator GW501516, and combinations of the PPAR-α activator fenofibrate with rosiglitazone or pioglitazone have encouraged attempts to develop single molecules that activate two or all three PPARs. Most effort has focussed on dual PPAR-α/γ activators. These reduce both hyperglycaemia and dyslipidaemia, but their development has been terminated by issues such as increased weight gain, oedema, plasma creatinine and myocardial infarction or stroke. In addition, the FDA has stated that many PPAR ligands submitted to it have caused increased numbers of tumours in carcinogenicity studies.Rather than aiming for full potent agonists, it may be best to identify subtype-selective partial agonists or compounds that selectively activate PPAR signalling pathways and use these in combination. Nutrients or modified lipids that are low-affinity agonists may also have potential.     

Balaglitazone: a second generation peroxisome proliferator-activated receptor (PPAR) gamma (γ) agonist

Balaglitazone (DRF-2593) is a novel partial agonist of PPAR-gamma (γ), which is developed by Dr. Reddy's laboratories India. Balaglitazone is a second generation peroxisome proliferator-activated receptor (PPAR) gamma agonist with only partial agonistic properties. Balaglitazone is currently being evaluated in phase III clinical trial in United States and Europe. Selective PPAR-γ modulators bind in distinct manners to the ligand-binding pocket of PPAR-γ, leading to alternative receptor conformations, differential cofactor recruitment/displacement, differential gene expression, and ultimately differential biological responses. Based on this concept, new and improved novel antidiabetic agents are in current development. Clinical studies conducted with 409 subjects of randomized, double blind, parallel-group placebo and active comparator-controlled subject groups to determine the efficacy and safety of Balaglitazone. The study showed that the trial met its primary endpoint. Balaglitazone treated groups shown significantly reduce of HbA1c (%), FSG (mmol/L), postprandial glucose as comparison to pioglitazone. Phase III clinical studies data clearly shows that Balaglitazone provides robust glycemic control as an add-on to insulin therapy. Balaglitazone 10 mg and 20 mg show the similar magnitudes of the effects which comparable to the effects seen in the pioglitazone 45 mg group. The incidence of fluid retention and fat accumulation fewer than those observed with pioglitazone 45 mg. Hence, Balaglitazone is prominent candidate of new glitazone which requires fewer doses as comparison pioglitazone and shows better safety profile less incidence of special adverse effect like heart failure, peripheral oedema, and myocardial infarction. Unlike other marketed PPAR gamma agonists, Balaglitazone shows less fluid retention, less heart enlargement and no reduction of bone formation than full PPAR gamma agonists in preclinical studies. In present review, we have tried to cover classification PPARs various ligands, chemistry, physical properties, commercial synthesis, current patent status, polymorphic information, receptor interaction, pharmacophore rational, mechanism, adverse effect and clinical status of Balaglitazone, giving emphasis on medicinal chemistry aspect.     

Discovery and development of selective PPARγ modulators as safe and effective antidiabetic agents

Importance of the field: PPARγ full agonists (pioglitazone and rosiglitazone) are the mainstay drugs for the treatment of type 2 diabetes; however, mechanism-based side effects have limited their full therapeutic potential. In recent years, much progress has been achieved in the discovery and development of selective PPARγ modulators (SPPARγMs) as safer alternatives to PPARγ full agonists.

Areas covered in this review: This review focuses on the preclinical and clinical data of all the SPPARγMs discovered so far, retrieved by searching PubMed, Prous Integrity database and company news updates from 1999 to date.

What the reader will gain: Here we thoroughly discuss SPPARγMs' mode of action, briefly examine new ways to identify superior SPPARγMs, and finally, compare and contrast the pharmacological and safety profile of various agents.

Take home message: The preclinical and clinical findings clearly suggest that selective PPARγ modulators have the potential to become the next generation of PPARγ agonists: effective insulin sensitizers with a superior safety profile to that of PPARγ full agonists.     

Selective peroxisome proliferator-activated receptor-γ modulation to reduce cardiovascular risk in patients with insulin resistance

The thiazolidinediones (TZDs) rosiglitazone and pioglitazone improve glucose homeostasis through activation of peroxisome proliferator-activated receptor (PPAR)-γ. Their use, however, has been limited due to adverse effects that include body weight gain and edema leading to congestive heart failure. Selective PPAR-γ modulators (SPPARMs) are second generation PPAR-γ ligands designed to improve insulin sensitivity with minimal undesirable effects associated with first generation PPAR-γ agonists. INT131 is one of the first SPPARMs to reach human trials. Early phase human studies with INT131 look promising with changes in plasma lipids and glucose being equal or better than what is seen with rosiglitazone and pioglitazone treatment but without evidence of edema. This profile of improved glucose homeostasis, improved plasma lipids, and reduced inflammation in the absence of edema would be expected to reduce cardiovascular risk in patients with Type 2 diabetes mellitus. Recent patents of novel approaches for the use of PPAR-γ related compounds with the potential for this improved risk-benefit ratio are discussed.     

Aleglitazar,a balanced PPARα/γ agonist,has no clinically relevant pharmacokinetic interaction with high-dose atorvastatin or rosuvastatin

Background: Aleglitazar, a dual PPAR-α/γ agonist, combines the lipid benefits of fibrates and the insulin-sensitizing benefits of thiazolidinediones.

Objective: To investigate the pharmacokinetic effects of co-administration of atorvastatin or rosuvastatin with aleglitazar.

Research design and methods: In a two-cohort, open-label, randomised, three-period crossover study, 44 healthy subjects received once-daily oral doses of aleglitazar 300 μg, statin (atorvastatin 80 mg or rosuvastatin 40 mg) and aleglitazar co-administered with each statin for 7 days. Plasma concentrations of each drug were measured and pharmacokinetic parameters determined on day 7 in each period.

Main outcome measures: Peak observed plasma concentration (C_max) and total exposures (AUC_{0 – 24}) of aleglitazar, atorvastatin and rosuvastatin.

Results: C_max and AUC_{0 – 24} to aleglitazar were similar, whether administered alone or in combination with a statin. Total exposure to either statin was unaffected by co-administration with aleglitazar. C_max treatment ratios for both statins exceeded the conventional no-effect boundary (1.25) when administered with aleglitazar.

Conclusions: Co-administration of aleglitazar with a statin does not alter the pharmacokinetic profile of either drug.     

Two thiophenes compounds are partial peroxisome proliferator-activated receptor α/γ dual agonists

In our previous study, two synthetic thiophenes such as IMB-05 and IMB-15 were found as peroxisome proliferator-activated receptor gamma (PPARγ) agonists and exhibited beneficial effects on glucose tolerance of diabetic mice in vivo. In the present study, their effect on the transactivity of other nuclear receptors was further investigated. IMB-05 and IMB-15 could not only activated PPARγ but also efficiently activate PPARα in GAL4-hPPARα/γ (ligand binding domain (LBD)) chimeric receptor assay and PPAR response element (PPRE)-luc reporter gene assay with EC(50) values of 1.8-5.2 μM, whereas no activity was observed in other nuclear receptor assays. In addition, the maximal efficacy of IMB-05 and IMB-15 in activating PPARα/γ was approximately 30% of that observed with Wy14643 and rosiglitazone. These data indicate that the two thiophene derivatives are novel class of partial PPARα/γ dual agonists, which may be the mechanism underlying their regulatory effects on glucose homeostasis.     

The Monascus metabolite monascin against TNF-α-induced insulin resistance via suppressing PPAR-γ phosphorylation in C2C12 myotubes

Chronic inflammation in muscle tissue causes insulin resistance and type-2 diabetes. Peroxisome proliferator-activated receptor (PPAR) ligands are reported to activate the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, including pioglitazone, which belong to the thiazolidinedione (TZD). Monascin (MS), a Monascus metabolite, has been reported to exert anti-inflammatory activity in our recent study. Therefore, the alleviating mechanism of MS on tumor necrosis factor-α (TNF-α; 20 ng/mL) induced insulin resistance in C2C12 cells was investigated in this study. Results showed that MS increased the uptake of 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-d-glucose (2-NBDG) in C2C12 myotubes. This result was associated with both PPAR-γ activity and PI3K/Akt pathway caused by MS inhibited p-JNK activity and prevented PPAR-γ phosphorylation. Moreover, we found that MS may act a PPAR-γ agonist to improve insulin sensitivity, and this issue was further confirmed by PPAR-γ antagonist (GW9662). Briefly, MS as pioglitazone, stabilized PPAR-γ structure and diminished PPAR-γ phosphorylation thereby improving insulin resistance.     

The use of PPAR-alpha/gamma dual agonists for the treatment of metabolic syndromes

This patent application describes chiral oxazole-arylpropionic acid derivatives that are effective as peroxisome proliferator-activated receptor-α/γ (PPARα/γ) dual agonists. Some of these compounds showed well-balanced affinity for both PPARα and PPARγ, as assessed by both binding and transactivation assays. The use of these compound(s) for the treatment and/or prevention of diseases which are mediated by PPARα and/or PPARγ, such as Type 2 diabetes, is claimed.     

选择性PPARγ调节剂治疗二型糖尿病的分子机制研究进展

第一类胰岛素增敏剂——过氧化物酶体增殖体激活受体γ(PPARγ)激动剂噻唑烷二酮类药物(TZDs)曾在二型糖尿病(T2DM)治疗中具有不可替代的作用。但由于TZDs类药物存在增重、水肿、骨折、充血性心力衰竭等严重副作用,保留TZDs类药物的胰岛素增敏效果而无其副作用的选择性PPARγ调节剂(SPPARγM)是新型胰岛素增敏剂的发展方向。现有实验主要对SPPARγM候选分子影响PPARγ受体构象改变、受体磷酸化、受体对共调节因子的选择性募集和PPARγ下游靶基因选择性开启等几个层次的分子作用机制作了初步探讨。该文综述了SPPARγM治疗二型糖尿病的分子机制研究进展。