Lack of efficacy of neutral endopeptidase inhibitor ecadotril in heart failure. The International Ecadotril Multi-centre Dose-ranging Study Investigators

Possible role of LCZ696 in atherosclerosis: new inroads and perspective

LCZ696 blocks both angiotensin receptor type 1 (ATR1) and neprilysin (NEP), which are intricate in the degradation of natriuretic peptides (NPs) and other endogenous peptides. It has been shown NEP inhibitors and LCZ696 could be effectively in the management of atherosclerosis (AS). However, the underlying mechanism of LCZ696 in AS is needed to be clarified entirely. Hence, this review is directed to reconnoiter the mechanistic role of LCZ696 in AS. The anti-inflammatory role of LCZ696 is related to the inhibition of transforming growth factor beta (TGF-β)-activated kinase 1 (TAK) and nod-like receptor pyrin 3 receptor (NLRP3) inflammasome. Moreover, LCZ696, via inhibition of pro-inflammatory cytokines, oxidative stress, apoptosis and endothelial dysfunction can attenuate the development and progression of AS. In conclusion, LCZ696 could be effective in the management of AS through modulation of inflammatory and oxidative signaling. Preclinical and clinical studies are recommended in this regard.

Neprilysin Inhibition in the Prevention of Anthracycline-Induced Cardiotoxicity

Anthracycline-induced cardiotoxicity (AIC) poses a clinical challenge in the management of cancer patients. AIC is characterized by myocardial systolic dysfunction and remodeling, caused by cardiomyocyte DNA damage, oxidative stress, mitochondrial dysfunction, or renin-angiotensin-aldosterone system (RAAS) dysregulation. In the past decade, after positive results of a PARADIGM-HF trial, a new class of drugs, namely angiotensin receptor/neprilysin inhibitors (ARNi), was incorporated into the management of patients with heart failure with reduced ejection fraction. As demonstrated in a variety of preclinical studies of cardiovascular diseases, the cardioprotective effects of ARNi administration are associated with decreased oxidative stress levels, the inhibition of myocardial inflammatory response, protection against mitochondrial damage and endothelial dysfunction, and improvement in the RAAS imbalance. However, data on ARNi's effectiveness in the prevention of AIC remains limited. Several reports of ARNi administration in animal models of AIC have shown promising results, as ARNi prevented ventricular systolic dysfunction and electrocardiographic changes and ameliorated oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, and the inflammatory response associated with anthracyclines. There is currently an ongoing PRADAII trial aimed to assess the efficacy of ARNi in patients receiving breast cancer treatment, which is expected to be completed by late 2025.

Renal events in patients receiving neprilysin inhibitors: a systematic review and meta-analysis

BACKGROUND

While it is well known that angiotensin-converting enzyme inhibitors (ACEi)/angiotensin receptor blockers (ARBs) increase the risk of acute renal failure, the role of neprilysin inhibition (NEPi) is unclear and some physicians are reluctant to prescribe sacubitril/valsartan because of safety concerns. This meta-analysis aimed to examine the risk for renal events, progression of chronic kidney disease (CKD) or progression to dialysis on combined NEPi and ACEi/ARBs compared with ACEi or ARBs.

METHODS

We performed a systematic meta-analysis including 17 randomized controlled trials (study drug sacubitril/valsartan or omapatrilat), involving a total of 23 569 patients, after searching PubMed, Cochrane, ClinicalTrials.org and Embase for eligible studies. From the included trials, all renal endpoints, including long- and short-term outcomes and hyperkalemia, were extracted. Pooled odds ratios (ORs) were calculated using the DerSimonian and Laird method. The study was registered at PROSPERO.

RESULTS

Overall, treatment with sacubitril/valsartan or omapatrilat showed a slightly lower risk of any renal event [OR 0.82 (0.7-0.97)] compared with treatment with an ACEi or ARB alone. Also, there was a decreased risk of severe acute renal events [OR 0.8 (0.69-0.93)] and a decrease in estimated glomerular filtration rate decline [mean difference -0.58 mL/min (-0.83 to -0.33 mL/min)]. There was no difference in chronic renal events [OR 0.92 (0.8-1.05)] or hyperkalemia [OR 1.02 (0.84-1.23)].

CONCLUSION

NEPi + ACEi/ARBs are safe in terms of renal adverse events. Longer trials focusing on CKD are needed to evaluate the effect of NEPi on decreasing progression of CKD.

Progress and prospects of Sacubitril/Valsartan: Based on heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is present in nearly half of patients with heart failure. The prevalence of heart failure with normal or near-normal ejection fractions increases more rapidly than in patients with reduced ejection fractions. Angiotensin-converting enzyme inhibitor (ACEI), angiotensin receptor blocker (ARB), aldosterone antagonist, β-blocker, and calcium channel blocker have not shown significant efficacy in HFpEF clinical trials. Sacubitril/Valsartan, combined angiotensin receptor blocker (Valsartan) with neprilysin inhibitor (Sacubitril), was the first-of-its-kind angiotensin receptor-neprilysin inhibitor (ARNI) to be developed. It has shown significant efficacy on HFpEF in recent studies. It is considered that most of the current Sacubitril/Valsartan studies are still concentrated in the field of heart failure, especially heart failure with reduced ejection fraction (HFrEF). This review discusses the latest advances in cardiovascular, renal, and metabolic aspects of Sacubitril/Valsartan, mainly in HFpEF, providing more evidence for further future research on Sacubitril/Valsartan and raising issues that should be paid attention. At the same time, this review will introduce the academic consensus on Sacubitril/Valsartan in treating HFpEF in China.

Neprilysin Inhibitors in Heart Failure: The Science, Mechanism of Action, Clinical Studies, and Unanswered Questions

This article provides a contemporary review and a new perspective on the role of neprilysin inhibition in heart failure (HF) in the context of recent clinical trials and addresses potential mechanisms and unanswered questions in certain HF patient populations. Neprilysin is an endopeptidase that cleaves a variety of peptides such as natriuretic peptides, bradykinin, adrenomedullin, substance P, angiotensin I and II, and endothelin. It has a broad role in cardiovascular, renal, pulmonary, gastrointestinal, endocrine, and neurologic functions. The combined angiotensin receptor and neprilysin inhibitor (ARNi) has been developed with an intent to increase vasodilatory natriuretic peptides and prevent counterregulatory activation of the angiotensin system. ARNi therapy is very effective in reducing the risks of death and hospitalization for HF in patients with HF and New York Heart Association functional class II to III symptoms, but studies failed to show any benefits with ARNi when compared with angiotensin-converting enzyme inhibitors or angiotensin receptor blocker in patients with advanced HF with reduced ejection fraction or in patients following myocardial infarction with left ventricular dysfunction but without HF. These raise the questions about whether the enzymatic breakdown of natriuretic peptides may not be a very effective solution in advanced HF patients when there is downstream blunting of the response to natriuretic peptides or among post-myocardial infarction patients in the absence of HF when there may not be a need for increased natriuretic peptide availability. Furthermore, there is a need for additional studies to determine the long-term effects of ARNi on albuminuria, obesity, glycemic control and lipid profile, blood pressure, and cognitive function in patients with HF.

Molecular mechanisms of sacubitril/valsartan in cardiac remodeling

Cardiovascular diseases have become a major clinical burden globally. Heart failure is one of the diseases that commonly emanates from progressive uncontrolled hypertension. This gives rise to the need for a new treatment for the disease. Sacubitril/valsartan is a new drug combination that has been approved for patients with heart failure. This review aims to detail the mechanism of action for sacubitril/valsartan in cardiac remodeling, a cellular and molecular process that occurs during the development of heart failure. Accumulating evidence has unveiled the cardioprotective effects of sacubitril/valsartan on cellular and molecular modulation in cardiac remodeling, with recent large-scale randomized clinical trials confirming its supremacy over other traditional heart failure treatments. However, its molecular mechanism of action in cardiac remodeling remains obscure. Therefore, comprehending the molecular mechanism of action of sacubitril/valsartan could help future research to study the drug’s potential therapy to reduce the severity of heart failure.

What the near Future Holds for Sacubitril/Valsartan: A Summary of Major Ongoing Studies

Early research on neprilysin inhibition showed that sacubitril/valsartan, a combination of the valsartan and the neprilysin inhibitor sacubitril, was superior to enalapril in patients with heart failure with reduced ejection fraction (HFrEF) in the PARADIGM-HF study in 2014. Therefore, for patients with HFrEF, worldwide recommendations have been reformed to include sacubitril/valsartan. In addition, sacubitril/valsartan has been investigated in other cardiovascular disease states, such as patients with heart failure and preserved ejection fraction (HFpEF) and following myocardial infarction (MI) events. In February 2021, the FDA expanded the indication use of sacubitril/valsartan to include the HFpEF patient population based on the results of the PARAGON-HF trial. However, randomized clinical trials post-MI did not show promising results. Sacubitril/valsartan is currently being investigated in many other cardiovascular and non-cardiovascular conditions. This review aims to shed light and summarize the ongoing sacubitril/valsartan registered studies on the United States National Library of Medicine clinical trials registry.

Emerging therapies: The potential roles SGLT2 inhibitors, GLP1 agonists, and ARNI therapy for ARNI pulmonary hypertension

Pulmonary hypertension (PH) is a highly morbid condition. PH due to left heart disease (PH-LHD) has no specific therapies and pulmonary arterial hypertension (PAH) has substantial residual risk despite several approved therapies. Multiple lines of experimental evidence link metabolic dysfunction to the pathogenesis and outcomes in PH-LHD and PAH, and novel metabolic agents hold promise to improve outcomes in these populations. The antidiabetic sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP1) agonists targeting metabolic dysfunction and improve outcomes in patients with LHD but have not been tested specifically in patients with PH. The angiotensin receptor/neprilysin inhibitors (ARNIs) produce significant improvements in cardiac hemodynamics and may improve metabolic dysfunction that could benefit the pulmonary circulation and right ventricle function. On the basis of promising preclinical work with these medications and clinical rationale, we explore the potential of SGLT2 inhibitors, GLP1 agonists, and ARNIs as therapies for both PH-LHD and PAH.

Toward a New Paradigm for Targeted Natriuretic Peptide Enhancement in Heart Failure

The natriuretic peptide system (NPS) plays a fundamental role in maintaining cardiorenal homeostasis, and its potent filling pressure-regulated diuretic and vasodilatory effects constitute a beneficial compensatory mechanism in heart failure (HF). Leveraging the NPS for therapeutic benefit in HF has been the subject of intense investigation during the last three decades and has ultimately reached widespread clinical use in the form of angiotensin receptor-neprilysin inhibition (ARNi). NPS enhancement via ARNi confers beneficial effects on mortality and hospitalization in HF, but inhibition of neprilysin leads to the accumulation of a number of other vasoactive peptides in the circulation, often resulting in hypotension and raising potential concerns over long-term adverse effects. Moreover, ARNi is less effective in the large group of HF patients with preserved ejection fraction. Alternative approaches for therapeutic augmentation of the NPS with increased specificity and efficacy are therefore warranted, and are now becoming feasible particularly with recent development of RNA therapeutics. In this review, the current state-of-the-art in terms of experimental and clinical strategies for NPS augmentation and their implementation will be reviewed and discussed.

Cardioprotective effects of early intervention with sacubitril/valsartan on pressure overloaded rat hearts

Left ventricular remodeling due to pressure overload is associated with poor prognosis. Sacubitril/valsartan is the first-in-class Angiotensin Receptor Neprilysin Inhibitor and has been demonstrated to have superior beneficial effects in the settings of heart failure. The aim of this study was to determine whether sacubitril/valsartan has cardioprotective effect in the early intervention of pressure overloaded hearts and whether it is superior to valsartan alone. We induced persistent left ventricular pressure overload in rats by ascending aortic constriction surgery and orally administrated sacubitril/valsartan, valsartan, or vehicle one week post operation for 10 weeks. We also determined the effects of sacubitril/valsartan over valsartan on adult ventricular myocytes and fibroblasts that were isolated from healthy rats and treated in culture. We found that early intervention with sacubitril/valsartan is superior to valsartan in reducing pressure overload-induced ventricular fibrosis and in reducing angiotensin II-induced adult ventricular fibroblast activation. While neither sacubitril/valsartan nor valsartan changes cardiac hypertrophy development, early intervention with sacubitril/valsartan protects ventricular myocytes from mitochondrial dysfunction and is superior to valsartan in reducing mitochondrial oxidative stress in response to persistent left ventricular pressure overload. In conclusion, our findings demonstrate that sacubitril/valsartan has a superior cardioprotective effect over valsartan in the early intervention of pressure overloaded hearts, which is independent of the reduction of left ventricular afterload. Our study provides evidence in support of potential benefits of the use of sacubitril/valsartan in patients with resistant hypertension or in patients with severe aortic stenosis.

Sympathoinhibitory effect of sacubitril-valsartan in heart failure with reduced ejection fraction: A pilot study

Chronic sympathetic nervous system (SNS) overactivity, characteristic of heart failure (HF) with reduced ejection fraction (HFrEF), is associated with poor prognosis and contributes to increased mortality risk. Sacubitril-valsartan is a recently approved, first-in-class, angiotensin receptor neprilysin inhibitor (ARNI) drug that markedly reduces the risks of death from cardiovascular causes and hospitalization for HF in patients with HFrEF, but the physiological mechanisms underlying these benefits are not fully understood. This single-arm, open-label, prospective study sought to test the hypothesis that short-term treatment with sacubitril-valsartan reduces SNS activity, measured directly via muscle sympathetic nerve activity (MSNA), in patients with HFrEF. MSNA, heart rate (HR), and arterial blood pressure (BP) were assessed in stable Class II and III patients with HFrEF (n = 9, 69 ± 8 yrs.; 28.6 ± 3.6 kg/m²) on contemporary, guideline-directed medical treatment who were subsequently started on sacubitril-valsartan. These measurements were repeated after two months of treatment with sacubitril-valsartan. Sacubitril-valsartan reduced MSNA burst frequency (baseline: 43 ± 10 bursts/min; 2-month: 36 ± 10 bursts/min, p = 0.05) and burst incidence (baseline: 68 ± 16 bursts/100 heartbeats; 2-month: 55 ± 16 bursts/100 heartbeats, p = 0.02), while HR and BP were unchanged following of treatment (p > 0.05). These preliminary findings provide new evidence regarding the ability of sacubitril-valsartan to rapidly reduce SNS activity in patients with HFrEF, suggesting the presence of a novel sympathoinhibitory effect of this new drug class.

Angiotensin Receptor-Neprilysin Inhibitors and the Natriuretic Peptide Axis

PURPOSE OF THE REVIEW

The purpose of this review is to describe the effects of angiotensin receptor neprilysin inhibitor (ARNI) therapy on the natriuretic peptide axis (NPA), with a particular focus on B-type natriuretic peptide (BNP), atrial natriuretic peptide (ANP), and C-type natriuretic peptide (CNP) to better understand the biology behind the improved outcomes in patients with heart failure with reduced ejection fraction (HFrEF).

RECENT FINDINGS

BNP, ANP, and CNP are the three main natriuretic peptides (NP); they share a common structure and ultimately mediate their actions by activating cyclic guanosine monophosphate (cGMP). ARNI therapy results in a decrease of N-terminal pro-BNP (NT-proBNP) and increase of BNP levels respectively. It is been questioned whether these changes may result from unique laboratory assays characteristics rather than actual biological implications. It appears to be that the prognostic accuracy of BNP for cardiovascular outcomes remains independent and comparable to that of NT-proBNP while on ARNI therapy. ANP levels also increase with ARNI therapy, but no consistent change has been described for CNP levels. There is evidence that the changes in BNP and NT-proBNP correlate with improvement in echocardiographic parameters of volume and function. The dual effect of neprilysin inhibition and angiotensin receptor blockade has substantial implications on the natriuretic peptide axis (NPA). The changes seen in BNP and NT-proBNP specifically have shown to correlate with improvement in echocardiographic parameters. Further results exploring the biologic effects of ARNI therapy on other NPs are still pending and likely will provide further insights in the mechanisms behind the improvement in cardiac function and clinical outcomes.

Myocardial protective effect of sacubitril-valsartan on rats with acute myocardial infarction

OBJECTIVE

The purpose of this study was to explore the effect of sacubitril-valsartan on rats with acute myocardial infarction.

METHODS

Sprague-dawley rats were randomly divided into six groups. Rats in Group A and B were threaded without deligation and treated with valsartan (34 mg/kg) or sacubitril-valsartan (68 mg/kg) after operation. Rats in Group C and D were given the two drugs (34 mg/kg, 68 mg/kg) after ligation of the left anterior descending branch for 40 minutes. Rats in Group E and F were restored the blood of the coronary artery after ligation, and given the two drugs (34 mg/kg, 68 mg/kg) at the same time. N-terminal pro-brain natriuretic peptide, high sensitivity troponin T, aldosterone and Cyclic guanosine monophosphate were measured and Color Doppler echocardiography was performed. Six weeks later, the rats were killed, the hearts were weighed and stained with Masson staining.

RESULTS

Compared with Group A and B, the levels of N-terminal pro-brain natriuretic peptide, high sensitivity troponin T, aldosterone and Cyclic guanosine monophosphate in other groups were significantly increased (p < 0.05). Before treatment, the left ventricular end diastolic diameter and left ventricular end systolic diameter were similar in each group. After treatment, the levels of left ventricular end diastolic diameter and left ventricular end systolic diameter, and collagen fiber range stained with blue in other groups were significantly increased in comparison with Group A and B (p < 0.05). In addition, the left ventricular volume and collagen fiber range stained with blue were notably decreased, the levels of ejection fraction (EF) were increased in sacubitril-valsartan groups in comparison with valsartan groups (p < 0.05).

CONCLUSION

Early application of sacubitril-valsartan has a protective effect on rats with acute myocardial infarction.

Natriuretic peptides and neprilysin inhibition in hypertension and hypertensive organ damage

The family of natriuretic peptides (NPs) discovered in mammalian tissues including cardiac atrium and brain consists of three members, namely, atrial, B- and C-type natriuretic peptides (ANP, BNP, CNP). Since the discovery, basic and clinical studies have been vigorously performed to explore the biological functions and pathophysiological roles of NPs in a wide range of diseases including hypertension and heart failure. These studies revealed that ANP and BNP are hormones secreted from the heart into the blood stream in response to pre- or after-load, counteracting blood pressure (BP) elevation and fluid retention through specific receptors. Meanwhile, CNP was found to be produced by the vascular endothelium, acting as a local mediator potentially serving protective functions for the blood vessels. Because NPs not only exert blood pressure lowering actions but also alleviate hypertensive organ damage, attempts have been made to develop therapeutic agents for hypertension by utilizing this family of NPs. One strategy is to inhibit neprilysin, an enzyme degrading NPs, thereby enhancing the actions of endogenous peptides. Recently, a dual inhibitor of angiotensin receptor-neprilysin was approved for heart failure, and neprilysin inhibition has also been shown to be beneficial in treating patients with hypertension. This review summarizes the roles of NPs in regulating BP, with special references to hypertension and hypertensive organ damage, and discusses the therapeutic implications of neprilysin inhibition.

Cardiovascular Outcomes with Sacubitril-Valsartan in Heart Failure: Emerging Clinical Data

One of the defining features of heart failure (HF) is neurohormonal activation. The renin-angiotensin-aldosterone-system (RAAS) and sympathetic nervous system (SNS) cause vasoconstriction and fluid retention and, in response, the secretion of natriuretic peptides (NPs) from volume and pressure-overloaded myocardium promotes vasodilation and diuresis. Inhibition of the RAAS with either angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) has been the cornerstone of medical treatment for HF with a reduced ejection fraction (HFrEF) but, until recently, it was unclear how the beneficial effects of NPs may be augmented in patients with HF. Neprilysin, a metalloproteinase widely distributed throughout the body, plays a role in degrading the gross excess of circulating NPs in patients with HF. Early studies of neprilysin inhibition suggested possible physiological benefits. In 2014, the PARADIGM-HF trial found that sacubitril-valsartan, a combination of the ARB valsartan, and the neprilysin inhibitor sacubitril, was superior to enalapril in patients with HFrEF, reducing the relative risk of cardiovascular (CV) death or first hospitalisation with HF by 20%. Almost half of the patients with HF symptoms have a “preserved” ejection fraction (HFpEF); however, the PARAGON-HF study found that sacubitril-valsartan in patients with LVEF ≥45% had no effect on CV death or first and recurrent hospitalisations with HF compared to valsartan. Guidelines across the world have changed to include sacubitril-valsartan for patients with HFrEF yet, nearly 6 years after PARADIGM-HF, there is still uncertainty as to when and in whom sacubitril-valsartan should be started. Furthermore, there may yet be subsets of patients with HFpEF who might benefit from treatment with sacubitril-valsartan. This review will describe the mechanisms behind the outcome benefit of sacubitril-valsartan in patients with HFrEF and to consider its future role in the management of patients with HF.

New pharmacotherapy for heart failure with reduced ejection fraction

INTRODUCTION

The European Society of Cardiology (ESC), Canadian Cardiovascular Society, and the American College of Cardiology Heart Failure (HF) guidelines all currently recommend the use of Angiotensin Converting Enzyme (ACE) inhibitors or Angiotensin Receptor Blockers (ARBs) and Beta Blockers (BB) in the treatment of HF with a reduced ejection fraction (HFrEF). Newer medications targeting combining an ARB with a neprilysin inhibitor (ARNI) sacubitril/valsartan have shown benefits in mortality and can be used in place of an ACE inhibitor or an ARB. Additionally, dapagliflozin, a medication targeting the sodium-glucose cotransporter 2 (SGLT2) can be used in addition to current therapies.

AREAS COVERED

This review provides a comprehensive analysis of the evidence around the new pharmacotherapies for HFrEF, specifically, sacubitril/valsartan and dapagliflozin. A comprehensive review of the literature using keywords such as heart failure with reduced ejection fraction, angiotensin receptor, neprilysin inhibitor, and sodium glucose transporter was conducted within the National Centre for Biotechnology Information (NCBI) and Google Scholar databases. The reference sections of articles were also examined to find additional articles.

EXPERT OPINION

Sacubitril/valsartan and dapagliflozin both show marked benefits on mortality in HFrEF patients. More research needs to be conducted on the mechanisms of action on disease modification.

Angiotensin receptor-neprilysin inhibitor for the treatment of heart failure: a review of recent evidence

Heart failure (HF) is a growing health concern in aging societies worldwide. Sacubitril/valsartan is changing the real-world treatment in the whole spectrum of HF. The beginning was the PARADIGM-HF trial published in 2014, which demonstrated the beneficial effects of inhibiting natriuretic peptide breakdown in combination with hindering the renin-angiotensin system in HF patients with a reduced ejection fraction. Subsequent large-scale randomized trials have evaluated angiotensin receptor-neprilysin inhibitor in HF patients with acute decompensation or with preserved ejection fraction. The post hoc analyses are being conducted as well. This review summarizes the recent evidence of sacubitril/ valsartan regarding patient-centered outcomes, based on randomized controlled trials and their associated studies.

Novel Therapeutic Approaches Targeting the Renin-Angiotensin System and Associated Peptides in Hypertension and Heart Failure

Despite the success of renin-angiotensin system (RAS) blockade by angiotensin-converting enzyme (ACE) inhibitors and angiotensin II type 1 receptor (AT1R) blockers, current therapies for hypertension and related cardiovascular diseases are still inadequate. Identification of additional components of the RAS and associated vasoactive pathways, as well as new structural and functional insights into established targets, have led to novel therapeutic approaches with the potential to provide improved cardiovascular protection and better blood pressure control and/or reduced adverse side effects. The simultaneous modulation of several neurohumoral mediators in key interconnected blood pressure-regulating pathways has been an attractive approach to improve treatment efficacy, and several novel approaches involve combination therapy or dual-acting agents. In addition, increased understanding of the complexity of the RAS has led to novel approaches aimed at upregulating the ACE2/angiotensin-(1-7)/Mas axis to counter-regulate the harmful effects of the ACE/angiotensin II/angiotensin III/AT1R axis. These advances have opened new avenues for the development of novel drugs targeting the RAS to better treat hypertension and heart failure. Here we focus on new therapies in preclinical and early clinical stages of development, including novel small molecule inhibitors and receptor agonists/antagonists, less conventional strategies such as gene therapy to suppress angiotensinogen at the RNA level, recombinant ACE2 protein, and novel bispecific designer peptides.

Interaction Between Sacubitril and Valsartan in Preventing Heart Failure Induced by Aortic Valve Insufficiency in Rats

BACKGROUND

Synergistic interactions between neprilysin inhibition (NEPi) with sacubitril and angiotensin receptor type1 blockade (ARB) with valsartan have been implicated in improvement of left ventricular (LV) contractility, relaxation, exercise tolerance, and fibrosis in preexisting heart failure (HF) induced by aortic valve insufficiency (AVI). It is not known whether this pharmacologic synergy can prevent cardiovascular pathology in a similar AVI model. Our aim was to investigate the pharmacology of sacubitril/valsartan in an experimental setting with therapy beginning immediately after creation of AVI.

METHODS

HF was induced through partial disruption of the aortic valve in rats. Therapy began 3 hours after valve disruption and lasted 8 weeks. Sacubitril/valsartan (68 mg/kg), valsartan (31 mg/kg), sacubitril (31 mg/kg), or vehicle were administered daily via oral gavage (N=8 in each group). Hemodynamic assessments were conducted using Millar technology, and an exercise tolerance test was conducted using a rodent treadmill.

RESULTS

Only sacubitril/valsartan increased total arterial compliance and ejection fraction (EF). Therapies with sacubitril/valsartan and valsartan similarly improved load-dependent (dP/dt_max) and load independent indices (Ees) of LV contractility, and exercise tolerance, whereas sacubitril did not. None of the therapies improved LV relaxation (dP/dt_min), whereas all reduced myocardial fibrosis.

CONCLUSIONS

1) The synergistic interaction between NEPi and ARB in early therapy with sacubitril/valsartan leads to increased total arterial compliance and EF. 2) Improvement in indices of LV contractility, and exercise tolerance with sacubitril/valsartan is likely because of ARB effect of valsartan. 3) All three therapies provided antifibrotic effects, suggesting both ARB and NEPi are capable of reducing myocardial fibrosis.

Neprilysin inhibition for pulmonary arterial hypertension: a randomized, double-blind, placebo-controlled, proof-of-concept trial

BACKGROUND AND PURPOSE

Pulmonary arterial hypertension (PAH) is an incurable, incapacitating disorder resulting from increased pulmonary vascular resistance, pulmonary arterial remodelling, and right ventricular failure. In preclinical models, the combination of a PDE5 inhibitor (PDE5i) with a neprilysin inhibitor augments natriuretic peptide bioactivity, promotes cGMP signalling, and reverses the structural and haemodynamic deficits that characterize PAH. Herein, we conducted a randomized, double-blind, placebo-controlled trial to assess the efficacy and safety of repurposing the neprilysin inhibitor, racecadotril, in PAH.

EXPERIMENTAL APPROACH

Twenty-one PAH patients stable on PDE5i therapy were recruited. Acute haemodynamic and biochemical changes following a single dose of racecadotril or matching placebo were determined; this was followed by a 14-day safety and efficacy evaluation. The primary endpoint in both steps was the maximum change in circulating atrial natriuretic peptide (ANP) concentration (Δ_max ), with secondary outcomes including pulmonary and systemic haemodynamics plus mechanistic biomarkers.

KEY RESULTS

Acute administration of racecadotril (100 mg) resulted in a 79% increase in the plasma ANP concentration and a 106% increase in plasma cGMP levels, with a concomitant 14% fall in pulmonary vascular resistance. Racecadotril (100 mg; t.i.d.) treatment for 14 days resulted in a 19% rise in plasma ANP concentration. Neither acute nor chronic administration of racecadotril resulted in a significant drop in mean arterial BP or any serious adverse effects.

CONCLUSIONS AND IMPLICATIONS

This Phase IIa evaluation provides proof-of-principle evidence that neprilysin inhibitors may have therapeutic utility in PAH and warrants a larger scale prospective trial.

Synergy between sacubitril and valsartan leads to hemodynamic, antifibrotic, and exercise tolerance benefits in rats with preexisting heart failure

Simultaneous neprilysin inhibition (NEPi) and angiotensin receptor blockade (ARB) with sacubitril/valsartan improves cardiac function and exercise tolerance in patients with heart failure. However, it is not known whether these therapeutic benefits are primarily due to NEPi with sacubitril or ARB with valsartan or their combination. Therefore, the aim of the present study was to investigate the potential contribution of sacubitril and valsartan to the benefits of the combination therapy on left ventricular (LV) function and exercise tolerance. Heart failure was induced by volume overload via partial disruption of the aortic valve in rats. Therapy began 4 wk after valve disruption and lasted through 8 wk. Drugs were administered daily via oral gavage [sacubitril/valsartan (68 mg/kg), valsartan (31 mg/kg), and sacubitril (31 mg/kg)]. Hemodynamic assessments were conducted using Millar technology, and an exercise tolerance test was conducted using a rodent treadmill. Therapy with sacubitril/valsartan improved load-dependent indexes of LV contractility (dP/d t_max) and relaxation (dP/d t_min), exercise tolerance, and mitigated myocardial fibrosis, whereas monotherapies with valsartan, or sacubitril did not. Both sacubitril/valsartan and valsartan similarly improved a load-independent index of contractility [slope of the end-systolic pressure-volume relationship ( E_es)]. Sacubitril did not improve E_es. First, synergy of NEPi with sacubitril and ARB with valsartan leads to the improvement of load-dependent LV contractility and relaxation, exercise tolerance, and reduction of myocardial collagen content. Second, the improvement in load-independent LV contractility with sacubitril/valsartan appears to be solely due to ARB with valsartan constituent. NEW & NOTEWORTHY Our data suggest the following explanation for the effects of sacubitril/valsartan: 1) synergy of sacubitril and valsartan leads to the improvement of load-dependent left ventricular contractility and relaxation, exercise tolerance, and reduction of myocardial fibrosis and 2) improvement in load-independent left ventricular contractility is solely due to the valsartan constituent. The findings offer a better understanding of the outcomes observed in clinical studies and might facilitate the continuing development of the next generations of angiotensin receptor neprilysin inhibitors.

A Novel Paradigm for Sacubitril/Valsartan: Beta-Endorphin Elevation as a Contributor to Exercise Tolerance Improvement in Rats With Preexisting Heart Failure Induced by Pressure Overload

BACKGROUND

Simultaneous angiotensin receptor (AT1) blockade and neprilysin inhibition with the use of sacubitril/valsartan has been recently approved to treat patients with heart failure (HF). Therapeutic benefits of this therapy have been attributed to natriuretic peptide elevation and AT1 receptor blockade. However, that pharmacologic picture may not be complete. The aims of this study were to investigate the pharmacology of sacubitril/valsartan compared with sacubitril and valsartan alone and to examine their impact on peptides up-regulated by neprilysin inhibition, such as beta-endorphin.

METHODS AND RESULTS

An HF model was induced by pressure overload via constriction of the suprarenal abdominal aorta in rats. Sacubitril/valsartan (68 mg/kg), valsartan (31 mg/kg), sacubitril (31 mg/kg), or placebo was administered by daily oral gavage (starting 4 weeks after pressure overload onset and continued for 4 additional weeks; n = 8 in each group). Exercise tolerance testing was conducted using a rodent treadmill and hemodynamic assessments were conducted under anesthesia with the use of Millar left ventricular (LV) conductance technology. Pressure overload led to exercise intolerance by 4 weeks and to hypertension and LV dysfunction and remodeling by 8 weeks. Both sacubitril/valsartan and sacubitril elevated beta-endorphin levels, by 40% and 54%, respectively, and improved exercise tolerance, by 93% and 112%, whereas valsartan did not. Indices of LV dysfunction persisted with the use of sacubitril/valsartan and valsartan therapies and even deteriorated in sacubitril group.

CONCLUSIONS

When added to valsartan, sacubitril increases beta-endorphin concentrations and improves exercise tolerance. These data suggest beta-endorphin elevation as a potential mechanism of action leading to improvement in exercise tolerance that is seen with sacubitril/valsartan. This therapeutic benefit is potentially independent from LV function.

New antihypertensive medications and clinical implications

Hypertension remains a global public health issue and is a leading preventable risk factor for many causes of mortality and morbidity. Although it is generally managed as an outpatient chronic disease, anaesthetists will inevitably encounter patients with hypertension, ranging from undiagnosed asymptomatic to chronic forms with end-organ damage(s). An understanding of perioperative management of anti-hypertensive pharmacotherapy is crucial. Although many drugs are familiar, new drug groups that have relevance for blood pressure control and perioperative care have evolved in recent years. This article also describes new antihypertensive agents currently available or under development that could impact perioperative management.

Sacubitril/valsartan in cardiovascular disease: evidence to date and place in therapy

Cardiovascular (CV) disease is a major cause of morbidity and mortality in the developing and the developed world. Mortality from CV disease had plateaued in the recent years raising concerning alarms about the sustained efficacy of available preventive and treatment options. Heart failure (HF) is among the major contributors to the CV-related health care burden, a persisting concern despite the use of clinically proven guideline-directed therapies. A requirement for more efficient medical therapies coupled with recent advances in bio-innovation led to the creation of sacubitril/valsartan, an angiotensin receptor-neprilysin inhibitor (ARNI), which demonstrated substantial CV benefit when compared with the standard of care, enalapril, in patients with HF and reduced ejection fraction. Further investigations of this novel combination ARNI at the tissue level shed light into the anti-remodeling and cardioprotective effects of sacubitril/valsartan, while clinical studies in the phenotypes of HF with preserved ejection fraction, hypertension and subsets, coronary outcomes, postmyocardial infarction, and renal disease suggested that this combination could be beneficial across a wide spectrum of CV disease. Sacubitril/valsartan is a much-needed therapeutic advance in the avenue of CV disease.

Role of Neprilysin Inhibitors in Heart Failure

Heart failure (HF) is a complex multifactorial medical condition that should be addressed according to its complexity and diversity. Currently, there is a medical arsenal available for the management of HF, but despite the advance in medical resources, its prevalence and social and financial impacts are still worrisome for the medical community and society. Among the numerous therapeutic options for the treatment of HF, neprilysin inhibitors have changed the perspective of the approach to titrate patients who suffer from this condition because neprilysin plays a role in the degradation of natriuretic peptides and various other vasoactive compounds that are crucial to counteract the devastating pathophysiology of HF. The purpose of this review was to analyze the role of neprilysin inhibitors in HF, focusing on newer therapy such as LCZ696 and studies that sustain its potential benefits in this medical entity.

Synthesis, secretion, function, metabolism and application of natriuretic peptides in heart failure

As a family of hormones with pleiotropic effects, natriuretic peptide (NP) system includes atrial NP (ANP), B-type NP (BNP), C-type NP (CNP), dendroaspis NP and urodilatin, with NP receptor-A (guanylate cyclase-A), NP receptor-B (guanylate cyclase-B) and NP receptor-C (clearance receptor). These peptides are genetically distinct, but structurally and functionally related for regulating circulatory homeostasis in vertebrates. In humans, ANP and BNP are encoded by NP precursor A (NPPA) and NPPB genes on chromosome 1, whereas CNP is encoded by NPPC on chromosome 2. NPs are synthesized and secreted through certain mechanisms by cardiomyocytes, fibroblasts, endotheliocytes, immune cells (neutrophils, T-cells and macrophages) and immature cells (embryonic stem cells, muscle satellite cells and cardiac precursor cells). They are mainly produced by cardiovascular, brain and renal tissues in response to wall stretch and other causes. NPs provide natriuresis, diuresis, vasodilation, antiproliferation, antihypertrophy, antifibrosis and other cardiometabolic protection. NPs represent body's own antihypertensive system, and provide compensatory protection to counterbalance vasoconstrictor-mitogenic-sodium retaining hormones, released by renin-angiotensin-aldosterone system (RAAS) and sympathetic nervous system (SNS). NPs play central roles in regulation of heart failure (HF), and are inactivated through not only NP receptor-C, but also neutral endopeptidase (NEP), dipeptidyl peptidase-4 and insulin degrading enzyme. Both BNP and N-terminal proBNP are useful biomarkers to not only make the diagnosis and assess the severity of HF, but also guide the therapy and predict the prognosis in patients with HF. Current NP-augmenting strategies include the synthesis of NPs or agonists to increase NP bioactivity and inhibition of NEP to reduce NP breakdown. Nesiritide has been established as an available therapy, and angiotensin receptor blocker NEP inhibitor (ARNI, LCZ696) has obtained extremely encouraging results with decreased morbidity and mortality. Novel pharmacological approaches based on NPs may promote a therapeutic shift from suppressing the RAAS and SNS to re-balancing neuroendocrine dysregulation in patients with HF. The current review discussed the synthesis, secretion, function and metabolism of NPs, and their diagnostic, therapeutic and prognostic values in HF.

Neprilysin and Natriuretic Peptide Regulation in Heart Failure

Neprilysin is acknowledged as a key player in neurohormonal regulation, a cornerstone of modern drug therapy in chronic heart failure. In the cardiovascular system, neprilysin cleaves numerous vasoactive peptides, some with mainly vasodilating effects (natriuretic peptides, adrenomedullin, bradykinin) and other with mainly vasoconstrictor effects (angiotensin I and II, endothelin-1). For decades, neprilysin has been an important biotarget. Academia and industry have combined active efforts to search for neprilysin inhibitors (NEPIs) that might be useful in clinical practice. NEPI monotherapy was initially tested with little success due to efficacy issues. Next, combination of NEPI and ACE-inhibiting activity agents were abandoned due to safety concerns. Recently, the combination of NEPI and ARB, also known as ARNI, has shown better than expected results in heart failure with reduced ejection fraction, and multitude of ongoing studies are set to prove its value across the heart failure spectrum.

LCZ696, a promising novel agent in treating hypertension (a meta-analysis of randomized controlled trials)

Background

To determine the effectiveness and safety of LCZ696 for the clinical treatment of hypertension, we performed a meta-analysis of the previous clinical trials.

Methods

Relevant English articles and randomized controlled trials were searched in Pubmed, Embase, EBSCO, Cochrane base and ClinicalTrials.gov. The last search date was July 20th, 2017.

Results

Compared with 20mg olmesartan, 200mg and 400mg LCZ696 outperformed olmesartan in terms of reducing mean sitting systolic blood pressure, mean ambulatory systolic blood pressure, mean sitting diastolic blood pressure and mean ambulatory diastolic blood pressure. Compared with 20mg olmesartan, 200mg and 400mg LCZ696 was better than olmesartan in terms of reducing mean sitting pulse pressure. And these studies showed that 400mg LCZ696 was better than 20mg olmesartan in terms of reducing mean ambulatory pulse pressure, however, there was no significant difference between 200mg LCZ696 and 20mg olmesartan in terms of redducing mean ambulatory pulse pressure. In addition, 200mg and 400mg LCZ696 was better than placebo in terms of reducing blood pressure parameters mentioned above. Compared with placebo or 20 mg olmesartan, LCZ696 showed no superiority in terms of reducing adverse events or serious adverse events.

Conclusions

LCZ696 at 200 mg or 400 mg was better at reducing most of blood pressure parameters than 20 mg olmesartan or placebo. Compared with placebo or 20 mg olmesartan, 200 mg or 400 mg LCZ696 do not result in more adverse events in treating hypertension.

Renin angiotensin aldosterone inhibition in the treatment of cardiovascular disease

A collective century of discoveries establishes the importance of the renin angiotensin aldosterone system in maintaining blood pressure, fluid volume and electrolyte homeostasis via autocrine, paracrine and endocrine signaling. While research continues to yield new functions of angiotensin II and angiotensin-(1-7), the gap between basic research and clinical application of these new findings is widening. As data accumulates on the efficacy of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers as drugs of fundamental importance in the treatment of cardiovascular and renal disorders, it is becoming apparent that the achieved clinical benefits is suboptimal and surprisingly no different than what can be achieved with other therapeutic interventions. We discuss this issue and summarize new pathways and mechanisms effecting the synthesis and actions of angiotensin II. The presence of renin-independent non-canonical pathways for angiotensin II production are largely unaffected by agents inhibiting renin angiotensin system activity. Hence, new efforts should be directed to develop drugs that can effectively block the synthesis and/or action of intracellular angiotensin II. Improved drug penetration into cardiac or renal sites of disease, inhibiting chymase the primary angiotensin II forming enzyme in the human heart, and/or inhibiting angiotensinogen synthesis would all be more effective strategies to inhibit the system. Additionally, given the role of angiotensin II in the maintenance of renal homeostatic mechanisms, any new inhibitor should possess greater selectivity of targeting pathogenic angiotensin II signaling processes and thereby limit inappropriate inhibition.

Neprilysin Inhibitors in Cardiovascular Disease

Mortality from heart failure remains high despite advances in medical therapy over the last three decades. Angiotensin receptor-neprilysin inhibitor (ARNI) combinations are the latest addition to the heart failure medical armamentarium, which is built on the cornerstone regimen of beta blockers, angiotensin converting enzyme (ACE) inhibitors/angiotensin receptor blockers, and aldosterone antagonists. Recent trial data have shown a significant mortality benefit from ARNIs, which, as of May 2016, have now received a class I recommendation for use in patients with heart failure and reduced ejection fraction from the major American and European cardiology societies.

Neprilysin Inhibition and the Treatment of Heart Failure: Recent Steps in the Right Direction

Numerous investigators have attempted to target the natriuretic peptide system in the treatment of heart failure since it was first described over 30 years ago. The history of neprilysin inhibition as a treatment for heart failure has been characterized by numerous setbacks. Recently, the PARADIGM-HF trial has shown favorable results, which may bring neprilysin inhibition into the mainstream of clinical practice. This article will review the history of the natriuretic peptide system and the investigations into it as a target for heart failure treatment, culminating in the positive results of the PARADIGM-HF trial, as well as planned and potential future directions for research.

The evolution of natriuretic peptide augmentation in management of heart failure and the role of sacubitril/valsartan

Heart failure (HF) is one of the leading causes of morbidity, mortality, and health care expenditures in the US and worldwide. For three decades, the pillars of treatment of HF with reduced ejection fraction (HFrEF) were medications that targeted the sympathetic nervous system (SNS) and the renin-angiotensin-aldosterone system (RAAS). Prior attempts to augment the natriuretic peptide system (NPS) for the management of HF failed either due to lack of significant clinical benefit or due to the unacceptable side effect profile. This review article will discuss the NPS, the failure of early drugs which targeted the NPS as therapies for HF, and the sequence of events which led to the development of sacubitril plus valsartan (Entresto; LCZ696; Novartis). LCZ696 has been shown to be superior to the standard of care available for treatment of HFrEF in several substantial hard endpoints including heart failure hospitalizations, cardiovascular mortality, and all-cause mortality.

Beneficial Effects of Combined AT1 Receptor/Neprilysin Inhibition (ARNI) Versus AT1 Receptor Blockade Alone in the Diabetic Eye

Purpose

Dysfunction of the renin-angiotensin system (RAS) contributes to pathogenesis of diabetic retinopathy (DR). Yet RAS blockers have only limited beneficial effects on progression of DR in clinical trials. The natriuretic peptide system offsets RAS, so that enhancing the activity of this system on top of RAS blockade might be beneficial. Neprilysin has an important role in the degradation of natriuretic peptides. Therefore, we hypothesize that dual angiotensin receptor-neprilysin inhibition (ARNI) may outperform angiotensin receptor blocker (ARB) in protection against DR. We tested this hypothesis in streptozotocin-induced diabetic transgenic (mRen2)27 rats.

Methods

Adult male diabetic (mRen2)27 rats were followed for 5 or 12 weeks. Treatment with vehicle, irbesartan (ARB), or ARB combined with the neprilysin inhibitor thiorphan (irbesartan+thiorphan [ARNI]) occurred during the final 3 weeks. Retinal cell death, gliosis, and capillary loss were evaluated. Real-time polymerase chain reaction (RT-PCR) analyses were performed to quantify the retinal level of inflammatory cell markers.

Results

Both ARB- and ARNI-treated groups showed similarly reduced retinal apoptotic cell death, gliosis, and capillary loss compared to the vehicle-treated group in the 5-week study. Treatment with ARNI reduced the expression of inflammatory markers more than ARB treatment in the 5-week study. In the 12-week study, ARNI treatment showed significantly more reduction in apoptotic cell death (51% vs. 25% reduction), and capillary loss (68% vs. 43% reduction) than ARB treatment.

Conclusions

Treatment with ARNI provides better protection against DR in diabetic (mRen2)27 transgenic rats, compared to ARB alone. This approach may be a promising treatment option for patients with DR.

Safety of the neprilysin/renin-angiotensin system inhibitor LCZ696

Objectives

The combined neprilysin/rennin-angiotensin system inhibitor sacubitril/valsartan (LCZ696) has shown its superiority over ACEI/ARB therapy. In view of the existing concern of its adverse effects, we aimed to provide evidence of the safety of the new drug.

Results

A total of 6 randomized trials with 11,821 subjects were included in this analysis. No significant differences were found in any adverse effects between LCZ696 and ACEI/ARB or placebo groups. LCZ696 significantly decreased the risks of serious adverse events and death compared with ACEI/ARB. LCZ696 also significantly decrease the risk of discontinuation of treatment for any adverse event no matter compared with ACEI/ARB or a placebo. LCZ696 significantly increased the risk of angioedema and dizziness, while it decreased the risk of renal dysfunction and bronchitis. There was no difference for hypotension, hyperkalemia, cough, upper respiratory tract inflammation, diarrhoea, back pain, nasopharyngitis, headache and influenza between the LCZ696 group and the ACEI/ARB group.

Materials and Methods

A meta-analysis of eligible studies that used LCZ696 in heart failure and hypertension was performed. Embase, PubMed and the Cochrane Library were searched for randomized controlled trials (RCTs) with data on any adverse effects, serious adverse events, discontinuation of treatment for any adverse event, death, angioedema, hypotension, hyperkalemia, and other adverse effects to perform this meta-analysis.

Conclusions

In addition to the beneficial effect of LCZ696 on end point events, the available evidences showed that LCZ696 was associated with less drug-risks than a placebo and ACEI/ARB.

Neprilysin inhibition in heart failure: mechanisms and substrates beyond modulating natriuretic peptides

The autonomic nervous system, the renin-angiotensin-aldosterone system, and the natriuretic peptide system represent critical regulatory pathways in heart failure and as such have been the major targets of pharmacological development. The introduction and approval of angiotensin receptor neprilysin inhibitors (ARNi) have broadened the available drug treatments of patients with chronic heart failure with reduced ejection fraction. Neprilysin catalyses the degradation of a number of vasodilator peptides, including the natriuretic peptides, bradykinin, substance P, and adrenomedullin, as well as vasoconstrictor peptides, including endothelin-1 and angiotensin I and II. We review the multiple, potentially competing, substrates for neprilysin inhibition, and the resultant composite clinical effects of ARNi therapy. A mechanistic understanding of this novel therapeutic class may provide important insights into the expected on-target and off-target effects when this agent is more widely prescribed.

Limitations of Sacubitril/Valsartan in the Management of Heart Failure

BACKGROUND

The PARADIGM-HF (Prospective comparison of ARNI with ACEI to Determine Impact on Global Mortality and morbidity in Heart Failure) trial was a double-blind trial that randomized 8442 patients with heart failure (HF) with reduced ejection fraction (HFrEF) to receive twice daily dosing of either 200 mg of LCZ696 or 10 mg of enalapril in addition to standard medical therapy for HF.

AREAS OF UNCERTAINTY

Limitations of this trial include (1) sacubitril has not been tested by itself in the treatment of HFrEF; (2) the maximum recommended dose of valsartan for the treatment of HFrEF was used in this trial, but the maximum recommended dose of enalapril for the treatment of HFrEF was not used; (3) a run-in phase was used in this trial to test the tolerability of LCZ696, and patients who had adverse effects in this period were excluded from randomization; (4) the percent of blacks enrolled in this trial was only 5%; (5) LCZ696 caused a 14% incidence of hypotension; (6) neprilysin inhibition might favor the development of Alzheimer dementia, which was not assessed in the PARADIGM-HF trial; (7) patients with severe symptomatic HF were underrepresented in this trial; (8) major exclusions from this trial included an acute coronary event in the last 3 months, severe pulmonary disease, hepatic impairment, and an estimated glomerular filtration rate <30 mL per minute per 1.73 m.

DATA SOURCES

Review of the PARADIGM-HF trial.

RESULTS

At 27-month follow-up, the PARADIGM-HF trial showed that compared with enalapril, LCZ696 reduced the composite of cardiovascular death or hospitalization for HF 20% (absolute risk reduction 4.7%, P < 0.001).

CONCLUSIONS

The numerous limitations discussed under the areas of uncertainty should be considered when prescribing LCZ696 for the treatment of HFrEF.

The Effects of LCZ696 in Patients With Hypertension Compared With Angiotensin Receptor Blockers

LCZ696, a first-in-class angiotensin receptor neprilysin inhibitor, has been demonstrated to have greater advantages in the treatment of heart failure compared with angiotensin-converting enzyme inhibitors, enalapril, or angiotensin receptor blockers (ARBs). However, studies that compared the efficacy and safety of LCZ696 against valsartan in patients with hypertension are limited. To provide further evidence for the benefits of LCZ696 and to make this assessment, a meta-analysis of randomized controlled trials (RCTs) was performed. The Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, MEDLINE, PubMed, and ClinicalTrials.gov were searched for RCTs. Twelve studies involving 3816 patients were eligible for inclusion. Seven studies compared LCZ696 with valsartan, and 5 studies compared LCZ696 with olmesartan. LCZ696 showed a significantly greater reduction in systolic blood pressure (BP; mean difference [MD] = −5.43 mm Hg; 95% confidence interval [CI]: −6.36 to −4.49 mm Hg; P < .001), diastolic BP (MD = −2.34 mm Hg; 95% CI: −2.67 to −2.01 mm Hg; P < .001), 24-hour ambulatory systolic BP (MD = −3.57 mm Hg, 95% CI: −4.29 to −2.85 mm Hg; P < .001), and 24-hour ambulatory diastolic BP (MD = −1.32 mm Hg, 95% CI: −1.77 to −0.78 mm Hg; P < .001) from the baseline than ARBs. LCZ696 was more effective in reducing BP (odds ratio [OR] = 5.34; 95% CI: 4.49-6.36; P < .01) and had a higher rate of BP control compared with ARBs (OR = 1.52; 95% CI: 1.37-1.69; P < .01). LCZ696 had no difference in the incidence of adverse events (OR = 1.05; 95% CI: 0.94-1.18; P = .38) or serious adverse events (OR = 0.80; 95% CI: 0.51-1.24; P = .31) compared to ARBs. This meta-analysis revealed that LCZ696 has a greater antihypertensive efficacy and an equal tolerability profile.

Chronic heart failure as a state of reduced effectiveness of the natriuretic peptide system: implications for therapy

Natriuretic peptides (NPs) promote diuresis, natriuresis and vasodilation in early chronic heart failure (CHF), countering renin-angiotensin-aldosterone system (RAAS) and sympathetic nervous system (SNS) overstimulation. Despite dramatic increases in circulating NP concentrations as CHF progresses, their effects become blunted. Increases in diuresis, natriuresis, and vasodilation after administration of exogenous atrial (ANP) or brain (BNP) natriuretic peptides are attenuated in patients with advanced CHF compared with controls. Several major factors may account for the reduced effectiveness of the natriuretic peptide system (NPS) in CHF. First, there is reduced availability of active forms of NPs, namely BNP. Second, target organ responsiveness becomes diminished. Third, the counter-regulatory hormones of the RAAS and SNS, and endothelin-1 become over-activated. Therefore, pharmacological approaches to enhance the functional effectiveness of the NPS in CHF have been explored in recent years. In terms of clinical outcomes, studies of synthetic BNP, or of neprilysin inhibitors alone or associated with an angiotensin converting enzyme inhibitor, have been controversial for several reasons. Recently, however, encouraging results have been obtained with the angiotensin receptor neprilysin inhibitor sacubitril/valsartan. The available data show that treatment with sacubitril/valsartan is associated with increased levels of NPs and their intracellular mediator cyclic guanosine monophosphate, suggesting improved functional effectiveness of the NPS, in addition to beneficial effects on mortality and morbidity outcomes. Therefore, combined targeting of the NPS and RAAS with sacubitril/valsartan emerges as the current optimal approach for redressing the neurohormonal imbalance in CHF.

Sacubitril/Valsartan (LCZ696) in Heart Failure

It has been known since the 1990s that long-term morbidity and mortality is improved in patients with heart failure with reduced ejection fraction (HFrEF) by treatments that target the renin-angiotensin-aldosterone system (RAAS). It has also long been thought that enhancement of the activity of natriuretic peptides (NPs) could potentially benefit patients with HFrEF, but multiple attempts to realize this benefit had failed over the years - until 2014, when a large, phase III, randomized, controlled clinical trial (PARADIGM-HF) was completed comparing sacubitril/valsartan with enalapril, a well-established treatment for HFrEF. Sacubitril/valsartan (formerly known as LCZ696) is a first-in-class angiotensin receptor neprilysin inhibitor (ARNI) that simultaneously suppresses RAAS activation through blockade of angiotensin II type 1 receptors and enhances vasoactive peptides including NPs through inhibition of neprilysin, the enzyme responsible for their degradation. In PARADIGM-HF, patients with HFrEF treated with sacubitril/valsartan had 20% less risk for cardiovascular death or hospitalization for heart failure (the primary endpoint), 20% less risk for cardiovascular death, 21% less risk for first hospitalization for heart failure, and 16% less risk for death from any cause, compared with enalapril (all p < 0.001). Concerning tolerability, the sacubitril/valsartan group had higher proportions of patients with hypotension and nonserious angioedema but lower proportions with renal impairment, hyperkalemia, and cough, compared with the enalapril group. The use of sacubitril/valsartan has been endorsed by the latest heart failure treatment guidelines in Europe and the USA. This chapter reviews the discoveries, scientific reasoning, and clinical evidence that led to the development of sacubitril/valsartan, the first novel therapy in a new drug class to improve survival in HFrEF in the last 15 years.

Sacubitril/valsartan in heart failure: latest evidence and place in therapy

Despite significant therapeutic advances, patients with chronic heart failure (HF) remain at high risk for HF progression and death. Sacubitril/valsartan (previously known as LCZ696) is a first-in-class medicine that contains a neprilysin (NEP) inhibitor (sacubitril) and an angiotensin II (Ang-II) receptor blocker (valsartan). NEP is an endopeptidase that metabolizes different vasoactive peptides including natriuretic peptides, bradykinin and Ang-II. In consequence, its inhibition increases mainly the levels of both, natriuretic peptides (promoting diuresis, natriuresis and vasodilatation) and Ang-II whose effects are blocked by the angiotensin receptor blocker, valsartan (reducing vasoconstriction and aldosterone release). Results from the 8442 patient PARADIGM-HF study showed in patients with New York Heart Association (NYHA) class II-IV and reduced ejection fraction treated with LCZ696 (versus enalapril), the following benefits: reduction of the risk of death from cardiovascular causes by 20%; reduction of HF hospitalizations by 21%; reduction of the risk of all-cause mortality by 16%. Overall there was a 20% risk reduction on the primary endpoint, composite measure of cardiovascular (CV) death or time to first HF hospitalization. PARADIGM-HF was stopped early after a median follow up of 27 months. Post hoc analyses of PARADIGM-HF as well as the place in therapy of sacubitril/valsartan, including future directions, are included in the present review.

Changing the treatment of heart failure with reduced ejection fraction: clinical use of sacubitril-valsartan combination

Despite significant therapeutic advances, patients with chronic heart failure (HF) remain at high risk of morbidity and mortality. Sacubitril valsartan (previously known as LCZ696) is a new oral agent approved for the treatment of symptomatic chronic heart failure in adults with reduced ejection fraction. It is described as the first in class angiotensin receptor neprilysin inhibitor (ARNI) since it incorporates the neprilysin inhibitor, sacubitril and the angiotensin II receptor antagonist, valsartan. Neprilysin is an endopeptidase that breaks down several vasoactive peptides including natriuretic peptides (NPs), bradykinin, endothelin and angiotensin II (Ang-II). Therefore, a natural consequence of its inhibition is an increase of plasmatic levels of both, NPs and Ang-II (with opposite biological actions). So, a combined inhibition of these both systems (Sacubitril / valsartan) may enhance the benefits of NPs effects in HF (natriuresis, diuresis, etc) while Ang-II receptor is inhibited (reducing vasoconstriction and aldosterone release). In a large clinical trial (PARADIGM-HF with 8442 patients), this new agent was found to significantly reduce cardiovascular and all cause mortality as well as hospitalizations due to HF (compared to enalapril). This manuscript reviews clinical evidence for sacubitril valsartan, dosing and cautions, future directions and its considered place in the therapy of HF with reduced ejection fraction.

Combined Angiotensin Receptor Antagonism and Neprilysin Inhibition

Heart failure affects ≈5.7 million people in the United States alone. Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, β-blockers, and aldosterone antagonists have improved mortality in patients with heart failure and reduced ejection fraction, but mortality remains high. In July 2015, the US Food and Drug Administration approved the first of a new class of drugs for the treatment of heart failure: Valsartan/sacubitril (formerly known as LCZ696 and currently marketed by Novartis as Entresto) combines the angiotensin receptor blocker valsartan and the neprilysin inhibitor prodrug sacubitril in a 1:1 ratio in a sodium supramolecular complex. Sacubitril is converted by esterases to LBQ657, which inhibits neprilysin, the enzyme responsible for the degradation of the natriuretic peptides and many other vasoactive peptides. Thus, this combined angiotensin receptor antagonist and neprilysin inhibitor addresses 2 of the pathophysiological mechanisms of heart failure: activation of the renin-angiotensin-aldosterone system and decreased sensitivity to natriuretic peptides. In the Prospective Comparison of ARNI With ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure (PARADIGM-HF) trial, valsartan/sacubitril significantly reduced mortality and hospitalization for heart failure, as well as blood pressure, compared with enalapril in patients with heart failure, reduced ejection fraction, and an elevated circulating level of brain natriuretic peptide or N-terminal pro-brain natriuretic peptide. Ongoing clinical trials are evaluating the role of valsartan/sacubitril in the treatment of heart failure with preserved ejection fraction and hypertension. We review here the mechanisms of action of valsartan/sacubitril, the pharmacological properties of the drug, and its efficacy and safety in the treatment of heart failure and hypertension.

Review of novel therapeutic targets for improving heart failure treatment based on experimental and clinical studies

Heart failure (HF) is a major public health priority due to its epidemiological transition and the world's aging population. HF is typified by continuous loss of contractile function with reduced, normal, or preserved ejection fraction, elevated vascular resistance, fluid and autonomic imbalance, and ventricular dilatation. Despite considerable advances in the treatment of HF over the past few decades, mortality remains substantial. Pharmacological treatments including β-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone antagonists have been proven to prolong the survival of patients with HF. However, there are still instances where patients remain symptomatic, despite optimal use of existing therapeutic agents. This understanding that patients with chronic HF progress into advanced stages despite receiving optimal treatment has increased the quest for alternatives, exploring the roles of additional pathways that contribute to the development and progression of HF. Several pharmacological targets associated with pathogenesis of HF have been identified and novel therapies have emerged. In this work, we review recent evidence from proposed mechanisms to the outcomes of experimental and clinical studies of the novel pharmacological agents that have emerged for the treatment of HF.