A novel aldosterone synthase inhibitor ameliorates mortality in pressure-overload mice with heart failure

Emerging trends in small molecule inhibitors targeting aldosterone synthase: A new paradigm in cardiovascular disease treatment

Aldosterone synthase (CYP11B2) is the rate-limiting enzyme in aldosterone production. In recent years, CYP11B2 has become an appealing target for treating conditions associated with excess aldosterone, such as hypertension, heart failure, and cardiometabolic diseases. Several small-molecule inhibitors of CYP11B2 have demonstrated efficacy in both preclinical studies and clinical trials. Among them, the tetrahydroisoquinoline derivative Baxdrostat has entered clinical trial phases and demonstrated efficacy in treating patients with hypertension. However, the high homology (>93 %) between CYP11B2 and steroid-11β-hydroxylase (CYP11B1), which catalyzes cortisol production, implies that insufficient drug specificity can lead to severe side effects. Developing selective inhibitors for CYP11B2 remains a considerable challenge that requires ongoing attention. This review summarizes recent research progress on small-molecule inhibitors targeting CYP11B2, focusing on structure-activity relationships (SAR) and structural optimization. It discusses strategies for enhancing the specificity and inhibitory activity of inhibitors, while also exploring potential applications and future prospects for CYP11B2 inhibitors, providing a theoretical foundation for developing the new generation of CYP11B2-targeted medications.

Identification of sulfonylpyrimidines as novel selective aldosterone synthase (CYP11B2) inhibitors

4-[(5-[2-Methyl-5-(methylsulfonyl)pentan-2-yl]sulfonylpyrimidin-4-yl)amino]benzonitrile 2 was identified as a novel potent aldosterone synthase inhibitor. Compound 2 was found to inhibit human CYP11B2 in the nanomolar range, and showed an aldosterone-lowering effect in a furosemide-treated cynomolgus monkey model. Although human CYP11B2 has the high homology sequence with human CYP11B1, compound 2 showed more than 80 times higher selectivity over human CYP11B1 in vitro.

Importance of Micromilieu for Pathophysiologic Mineralocorticoid Receptor Activity—When the Mineralocorticoid Receptor Resides in the Wrong Neighborhood

The mineralocorticoid receptor (MR) is a member of the steroid receptor family and acts as a ligand-dependent transcription factor. In addition to its classical effects on water and electrolyte balance, its involvement in the pathogenesis of cardiovascular and renal diseases has been the subject of research for several years. The molecular basis of the latter has not been fully elucidated, but an isolated increase in the concentration of the MR ligand aldosterone or MR expression does not suffice to explain long-term pathologic actions of the receptor. Several studies suggest that MR activity and signal transduction are modulated by the surrounding microenvironment, which therefore plays an important role in MR pathophysiological effects. Local changes in micromilieu, including hypoxia, ischemia/reperfusion, inflammation, radical stress, and aberrant salt or glucose concentrations affect MR activation and therefore may influence the probability of unphysiological MR actions. The surrounding micromilieu may modulate genomic MR activity either by causing changes in MR expression or MR activity; for example, by inducing posttranslational modifications of the MR or novel interaction with coregulators, DNA-binding sites, or non-classical pathways. This should be considered when developing treatment options and strategies for prevention of MR-associated diseases.

Aldosterone synthase inhibitors for cardiovascular diseases: A comprehensive review of preclinical, clinical and in silico data

Aldosterone, the main mineralocorticoid hormone, plays a fundamental role in maintaining blood pressure (BP)and volume under hypovolemic conditions. However, in numerous diseases, where it is produced in excess, it plays a detrimental role and contributes to cardiovascular events and ultimately to death in a multitude of patients. The seminal observation that the fungicide-derivative fadrozole blunted steroidogenesis has led to develop several agents to inhibit aldosterone synthase (AS, CYP11B2), the mitochondrial NADH-dependent enzyme that is necessary for aldosterone biosynthesis. Aldosterone synthase inhibitors (ASI) have, thereafter, been conceived and investigated in phase I and phase II studies. We herein reviewed the ASIs available so far considering their chemical structure, the related aldosterone synthase binding and pharmacodynamic properties. We also examined the promising results obtained with ASIs that have already been tested in phase II human studies.

The endothelial mineralocorticoid receptor: Contributions to sex differences in cardiovascular disease

Cardiovascular disease remains the leading cause of death for both men and women. The observation that premenopausal women are protected from cardiovascular disease relative to age-matched men, and that this protection is lost with menopause, has led to extensive study of the role of sex steroid hormones in the pathogenesis of cardiovascular disease. However, the molecular basis for sex differences in cardiovascular disease is still not fully understood, limiting the ability to tailor therapies to male and female patients. Therefore, there is a growing need to investigate molecular pathways outside of traditional sex hormone signaling to fully understand sex differences in cardiovascular disease. Emerging evidence points to the mineralocorticoid receptor (MR), a steroid hormone receptor activated by the adrenal hormone aldosterone, as one such mediator of cardiovascular disease risk, potentially serving as a sex-dependent link between cardiovascular risk factors and disease. Enhanced activation of the MR by aldosterone is associated with increased risk of cardiovascular disease. Emerging evidence implicates the MR specifically within the endothelial cells lining the blood vessels in mediating some of the sex differences observed in cardiovascular pathology. This review summarizes the available clinical and preclinical literature concerning the role of the MR in the pathophysiology of endothelial dysfunction, hypertension, atherosclerosis, and heart failure, with a special emphasis on sex differences in the role of endothelial-specific MR in these pathologies. The available data regarding the molecular mechanisms by which endothelial-specific MR may contribute to sex differences in cardiovascular disease is also summarized. A paradigm emerges from synthesis of the literature in which endothelial-specific MR regulates vascular function in a sex-dependent manner in response to cardiovascular risk factors to contribute to disease. Limitations in this field include the relative paucity of women in clinical trials and, until recently, the nearly exclusive use of male animals in preclinical investigations. Enhanced understanding of the sex-specific roles of endothelial MR could lead to novel mechanistic insights underlying sex differences in cardiovascular disease incidence and outcomes and could identify additional therapeutic targets to effectively treat cardiovascular disease in men and women.

Inhibitors of Aldosterone Synthase

The mineralocorticoid aldosterone is an important regulator of blood pressure and electrolyte balance. However, excess aldosterone can be deleterious as a driver of inflammation, vascular remodeling and tissue fibrosis associated with cardiometabolic diseases. Mineralocorticoid receptor antagonists (MRA) and renin-angiotensin-aldosterone system (RAAS) antagonists are current clinical therapies used to antagonize deleterious effects of aldosterone in patients. MRAs compete with aldosterone for binding at its cognate receptor thereby limiting its effect while RAS antagonists reduce aldosterone levels indirectly by blocking the stimulatory effect of angiotensin. Both MRAs and RAS antagonists can result in incomplete inhibition of the harmful effects of excess aldosterone. Aldosterone synthase (AS) inhibitors (ASI) attenuate the production of aldosterone directly and have been proposed as an alternative to MRAs and RAS blockers. Cortisol synthase (CS) is an enzyme closely related to AS and responsible for generating the important glucocorticoid cortisol, required for maintaining critical metabolic and immune responses. The importance of selectivity against CS is shown by early examples of ASIs that were only modestly selective and as such, attenuated cortisol responses when evaluated in patients. Recently, next-generation, highly selective ASIs have been described and are presently being evaluated in the clinic as an alternative to angiotensin and MR antagonists for cardiometabolic disease. Herein we provide a brief review of the challenges associated with discovery of selective ASIs and the transition from the early compounds that paved the way toward the next-generation of highly selective ASIs currently under development.

Newer hormonal pharmacotherapies for heart failure

INTRODUCTION

Heart failure (HF) is characterized by maladaptive neurohormonal activation of the cardiovascular and renal systems resulting in circulatory inadequacy and frequent acute exacerbations. The increasing burden of HF prompted investigation of underlying pathophysiological mechanisms and the design of pharmacotherapeutics that would target these pathways.

AREAS COVERED

A MEDLINE search for relevant original investigations and review articles of newer hormonal drugs for HF since the year 2005 till October 2017 provided us with necessary literature. Major trials and relevant clinical investigations were discussed.

EXPERT COMMENTARY

A multitude of hormonal pathways central to HF were identified, including the natriuretic peptide system and neurohormones such as relaxin, arginine vasopressin, and endothelin. However, drugs targeting these novel pathways (aliskiren, tolvaptan, ularitide, serelaxin, bosentan, macitentan) failed to show mortality benefit. This emphasizes a tremendous unmet need in the pharmacotherapy for HF, especially for the subtypes of acute HF and HF with preserved ejection fraction. Sacubitril/valsartan demonstrated substantial mortality benefit in chronic systolic HF population and is endorsed by international HF guidelines. If proven to be efficacious in larger outcome trials, finerenone can be a valuable addition baseline HF therapy. More basic, translational, and phenotype specific clinical research is warranted to improve HF pharmacotherapy.

Heart failure with preserved ejection fraction: current management and future strategies : Expert opinion on the behalf of the Nucleus of the "Heart Failure Working Group" of the German Society of Cardiology (DKG)

About 50% of all patients suffering from heart failure (HF) exhibit a reduced ejection fraction (EF ≤ 40%), termed HFrEF. The others may be classified into HF with midrange EF (HFmrEF 40-50%) or preserved ejection fraction (HFpEF, EF ≥ 50%). Presentation and pathophysiology of HFpEF is heterogeneous and its management remains a challenge since evidence of therapeutic benefits on outcome is scarce. Up to now, there are no therapies improving survival in patients with HFpEF. Thus, the treatment targets symptom relief, quality of life and reduction of cardiac decompensations by controlling fluid retention and managing risk factors and comorbidities. As such, renin-angiotensin-aldosterone inhibitors, diuretics, calcium channel blockers (CBB) and beta-blockers, diet and exercise recommendations are still important in HFpEF, although these interventions are not proven to reduce mortality in large randomized controlled trials. Recently, numerous new treatment targets have been identified, which are further investigated in studies using, e.g. soluble guanylate cyclase stimulators, inorganic nitrates, the angiotensin receptor neprilysin inhibitor LCZ 696, and SGLT2 inhibitors. In addition, several devices such as the CardioMEMS, interatrial septal devices (IASD), cardiac contractility modulation (CCM), renal denervation, and baroreflex activation therapy (BAT) were investigated in different forms of HFpEF populations and some of them have the potency to offer new hopes for patients suffering from HFpEF. On the basic research field side, lot of new disease-modifying strategies are under development including anti-inflammatory drugs, mitochondrial-targeted antioxidants, new anti-fibrotic and microRNA-guided interventions are under investigation and showed already promising results. This review addresses available data of current best clinical practice and management approaches based on expert experiences and summarizes novel approaches towards HFpEF.