Efficacy of Angiotensin Receptor-Neprilysin Inhibitor and Its Renal Outcome in Heart Failure Patients: A Systematic Review of Randomized Clinical Trials.

Heart failure (HF) is a major cause of morbidity and mortality and imposes a significant financial burden on healthcare systems globally. Angiotensin receptor-neprilysin inhibitor (ARNI), a novel neuroendocrine inhibitor, is frequently used in treating HF. However, there is still limited understanding regarding how it compares to other neuroendocrine inhibitors, such as angiotensin-converting enzyme inhibitors (ACEis) and angiotensin receptor blockers (ARBs). The purpose of this research is to present the most recent data regarding the efficacy and renal impact of ARNIs in the treatment of HF in comparison to ACE inhibitors and ARBs. Several large-scale randomized controlled trials (RCTs) have recently been conducted to evaluate the benefits of this drug in patients with different types of HF, regardless of their renal status. We searched multiple databases, including PubMed, PubMed Central (PMC), and Google Scholar, to find relevant RCTs. The efficacy outcome was a composite of the rate of death from cardiovascular causes, the frequency of HF hospitalizations (HFH), and alterations in N-terminal pro-brain natriuretic peptide (NT-proBNP) levels. The renal outcome was impairment of renal function. This systematic review analyzed large-scale RCTs involving 17,327 participants, with an average follow-up time of approximately 2.9 years. sacubitril/valsartan showed notable improvements compared to ACEis and ARBs in the following areas: reduction in NT-proBNP levels, prevention of further deterioration in renal function, and decreased hospitalizations for HF. Interestingly, there is no increased risk of mortality from cardiovascular causes with sacubitril or valsartan.

Efficacy and safety analysis of angiotensin receptor neprilysin inhibition(ARNI)in patients with heart failure: a real-world retrospective study.

BACKGROUND: In a large randomized controlled trial (PARADIGM-HF), ARNI has been shown to significantly reduce cardiovascular mortality and hospitalization for patients with reduced ejection fraction in heart failure. This study analyzed the efficacy and safety of ARNI on the basis of various types of heart failure patients in southwestern Sichuan Province. METHODS: This study included patients with heart failure who were treated at the Affiliated Hospital of North Sichuan Medical College from July 2017 to June 2021. This study analyzed the efficacy and safety of ARNI in the treatment of heart failure, and analyzed the risk factors for readmission after ARNI treatment. RESULTS: After propensity score matching, a total of 778 patients were included in the study. The readmission rate for heart failure in patients treated with ARNI (8.7%) was significantly lower than that in the standard treatment group (14.5%) (P = 0.023). Both the proportion of patients with increased LVEF and with decreased LVEF were higher in the ARNI treatment group than in the conventional therapy group. Compared with receiving standard medical treatment, combined ARNI treatment resulted in a greater reduction in SBP (-10.00, 95%CI: -24.00-1.50 vs. -7.00, 95%CI: -20.00-4.14; P = 0.016) in HF patients. Combination ARNI therapy did not increase the risk of adverse events. The study found that age (> 65 vs. ≤65 years) (OR = 4.038, 95%CI: 1.360-13.641, P = 0.013) and HFrEF (OR = 3.162, 95%CI: 1.028-9.724, P = 0.045) were independent predictors of readmission in HF patients treated with ARNI. CONCLUSION: Patients with heart failure treated with ARNI can improve clinical symptoms and reduce the risk of readmitted hospital admission. Age > ~ 65 years and HFrEF were independent predictors of readmission in HF patients treated in ARNI group.

Sacubitril/valsartan reverses cardiac structure and function in experimental model of hypertension-induced hypertrophic cardiomyopathy.

This study evaluated the effect of sacubtril/valsartan on cardiac remodeling, molecular and cellular adaptations in experimental (rat) model of hypertension-induced hypertrophic cardiomyopathy. Thirty Wistar Kyoto rats, 10 healthy (control) and 20 rats with confirmed hypertension-induced hypertrophic cardiomyopathy (HpCM), were used for this study. The HpCM group was further subdivided into untreated and sacubitril/valsartan-treated groups. Myocardial structure and function were assessed using echocardiography, Langendorff's isolated heart experiment, blood sampling and qualitative polymerase chain reaction. Echocardiographic examinations revealed protective effects of sacubitril/valsartan by improving left ventricular internal diameter in systole and diastole and fractional shortening. Additionally, sacubitril/valsartan treatment decreased systolic and diastolic blood pressures in comparison with untreated hypertensive rats. Moreover, sacubitril/valsartan treatment reduced oxidative stress and apoptosis (reduced expression of Bax and Cas9 genes) compared to untreated rats. There was a regular histomorphology of cardiomyocytes, interstitium, and blood vessels in treated rats compared to untreated HpCM rats which expressed hypertrophic cardiomyocytes, with polymorphic nuclei, prominent nucleoli and moderately dilated interstitium. In experimental model of hypertension-induced hypertrophic cardiomyopathy, sacubitril/valsartan treatment led to improved cardiac structure, haemodynamic performance, and reduced oxidative stress and apoptosis. Sacubitril/valsartan thus presents as a potential therapeutic strategy resulted in hypertension-induced hypertrophic cardiomyopathy.

Sacubitril/valsartan versus ramipril for patients with acute myocardial infarction: win-ratio analysis of the PARADISE-MI trial.

AIM: The win ratio can incorporate different types of outcomes and enhance statistical power, making it a useful method for analysing composite outcomes in cardiovascular trials. The application of this approach to the PARADISE-MI trial provides an additional perspective into understanding the effects of sacubitril/valsartan in patients with acute myocardial infarction. METHODS AND RESULTS: We conducted a post-hoc analysis of the PARADISE-MI trial, which randomly assigned patients with acute myocardial infarction complicated by a reduced left ventricular ejection fraction, pulmonary congestion, or both to receive either sacubitril/valsartan (97 mg of sacubitril and 103 mg of valsartan twice daily) or ramipril (5 mg twice daily) in addition to guideline-recommended therapy. The principal composite outcome was analysed in the hierarchical order of death due to cardiovascular causes, first hospitalization for heart failure, and first outpatient episode of symptomatic heart failure. We included events confirmed by the clinical events classification (CEC) committee as well as events identified by investigators that did not meet study definitions. Results were analysed by the unmatched win-ratio method. A win ratio that exceeds 1.00 reflects a better outcome. A total of 5661 patients underwent randomization; 2830 were assigned to receive sacubitril/valsartan and 2831 to receive ramipril. The hierarchical analysis of the principal composite outcome demonstrated a larger number of wins (1 265 767 [15.7%]) than losses (1 079 502 [13.4%]) in the sacubitril/valsartan group (win ratio of 1.17, 95% confidence interval [CI] 1.03-1.33; p = 0.015). Sensitivity analyses using alternative definitions of the composite outcome showed results similar to those of the principal analysis, except for analysis restricted to events that met CEC definitions (win ratio of 1.11, 95% CI 0.96-1.30; p = 0.16). CONCLUSION: In this post-hoc analysis of the PARADISE-MI trial using the win ratio and including investigator-identified events not having CEC confirmation, sacubitril/valsartan was superior to ramipril among high-risk survivors of acute myocardial infarction.

Remodelling is inversely proportional to left ventricular dimensions in a real-life population of patients with chronic heart failure after therapy with sacubitril/valsartan.

BACKGROUND: Left ventricular (LV) remodelling is a major mechanism underlying disease progression in patients with heart failure (HF) with reduced ejection fraction (EF). Previous studies that LVEF improvement and reverse remodelling can be achieved after therapy with Sacubitril/Valsartan in real-world settings. Therefore, we sought to investigate possible predictors of LV remodelling, in particular echocardiographic parameters derived by Tissue Doppler Imaging. METHODS: Patients with chronic HF, LV dysfunction (EF < 35%), NYHA class II-III were followed up between September 2016 and January 2019. All patients underwent clinical and echocardiography follow up at baseline and after 12 months of therapy with sacubitril/valsartan. RESULTS: Fifty-four consecutive outpatients were enrolled in the study. At follow-up visit LVEF (38 ± 9 vs. 30 ± 5%, p < 0.0001), LVEDD (61 ± 8 vs. 62 ± 8 mm, p = 0.0085), LVESV (114 ± 57 vs. 130 ± 56 mm3, p = 0.0001), mitral regurgitation severity (1 ± 1 vs. 2 ± 1, p < 0.0001), and left atrial area (23 ± 6 vs. 24 ± 6 mm2, p = 0.0121) changed compared to the baseline value. Changes in LVEF (follow up vs baseline) correlated with baseline levels of heart rate (r = 0.24, p = 0.048), LVEDD (r= -0.33, p = 0.004), LVEDV (r= -0.39, p = 0.001), LVESV (r = 0.37, p = 0.002), and changes in LVESV (r=-0.34, p = 0.006). Correlations remained significant even after correction at multivariate analysis including age and gender. CONCLUSIONS: Treatment with sacubitril/valsartan in patients with systolic dysfunction is associated with an improvement in LVEF in a real world scenario. Smaller LV volumes are associated with better reverse LV remodelling.

Potential effects and application prospect of angiotensin receptor-neprilysin inhibitor in diabetic kidney disease.

Diabetic kidney disease (DKD) is one of the main causes of end-stage renal disease (ESRD) and all-cause mortality in diabetic patients, despite the extensive use of angiotensin-converting enzyme inhibitor (ACEI) and angiotensin II receptor blocker (ARB). Angiotensin receptor-neprilysin inhibitor (ARNI), combining ARB and neutral endopeptidase inhibitor (NEPI), is likely to have potential favorable effects in DKD. This review summarizes existing preclinical and clinical studies on mechanism of ARNI and its potential effects on DKD. In preclinical studies, ARNI manifested its renoprotective effects by improving natriuresis, ameliorating inflammation, oxidative stress and renal dysfunction, and slowing down glomerulosclerosis and tubulointerstitial injury of kidney, but its effect on proteinuria is still controversial. Beneficial effects of ARNI on blood glucose regulation and glycometabolism have also been reported. There are no clinical studies of ARNI that specifically focus on DKD patients so far. ARNI has application potential in DKD, but there still need clinical studies that focus on DKD patients to determine its effectiveness, safety and underlying mechanism.

Sacubitril-Valsartan, Clinical Benefits and Related Mechanisms of Action in Heart Failure With Reduced Ejection Fraction. A Review.

Heart failure (HF) is a clinical syndrome characterized by the presence of dyspnea or limited exertion due to impaired cardiac ventricular filling and/or blood ejection. Because of its high prevalence, it is a major health and economic burden worldwide. Several mechanisms are involved in the pathophysiology of HF. First, the renin-angiotensin-aldosterone system (RAAS) is over-activated, causing vasoconstriction, hypertension, elevated aldosterone levels and sympathetic tone, and eventually cardiac remodeling. Second, an endogenous compensatory mechanism, the natriuretic peptide (NP) system is also activated, albeit insufficiently to counteract the RAAS effects. Since NPs are degraded by the enzyme neprilysin, it was hypothesized that its inhibition could be an important therapeutic target in HF. Sacubitril/valsartan is the first of the class of dual neprilysin and angiotensin receptor inhibitors (ARNI). In patients with HFrEF, treatment with sacubitril/valsartan has demonstrated to significantly reduce mortality and the rates of hospitalization and rehospitalization for HF when compared to enalapril. This communication reviews in detail the demonstrated benefits of sacubitril/valsartan in the treatment of patients with HFrEF, including reduction of mortality and disease progression as well as improvement in cardiac remodeling and quality of life. The hemodynamic and organic effects arising from its dual mechanism of action, including the impact of neprilysin inhibition at the renal level, especially relevant in patients with type 2 diabetes mellitus, are also reviewed. Finally, the evidence on the demonstrated safety and tolerability profile of sacubitril/valsartan in the different subpopulations studied has been compiled. The review of this evidence, together with the recommendations of the latest clinical guidelines, position sacubitril/valsartan as a fundamental pillar in the treatment of patients with HFrEF.

Sacubitril/valsartan inhibits obesity-associated diastolic dysfunction through suppression of ventricular-vascular stiffness.

OBJECTIVE: Cardiac diastolic dysfunction (DD) and arterial stiffness are early manifestations of obesity-associated prediabetes, and both serve as risk factors for the development of heart failure with preserved ejection fraction (HFpEF). Since the incidence of DD and arterial stiffness are increasing worldwide due to exponential growth in obesity, an effective treatment is urgently needed to blunt their development and progression. Here we investigated whether the combination of an inhibitor of neprilysin (sacubitril), a natriuretic peptide-degrading enzyme, and an angiotensin II type 1 receptor blocker (valsartan), suppresses DD and arterial stiffness in an animal model of prediabetes more effectively than valsartan monotherapy. METHODS: Sixteen-week-old male Zucker Obese rats (ZO; n = 64) were assigned randomly to 4 different groups: Group 1: saline control (ZOC); Group 2: sacubitril/valsartan (sac/val; 68 mg•kg-1•day-1; ZOSV); Group 3: valsartan (31 mg•kg-1•day-1; ZOV) and Group 4: hydralazine, an anti-hypertensive drug (30 mg•kg-1•day-1; ZOH). Six Zucker Lean (ZL) rats that received saline only (Group 5) served as lean controls (ZLC). Drugs were administered daily for 10 weeks by oral gavage. RESULTS: Sac/val improved echocardiographic parameters of impaired left ventricular (LV) stiffness in untreated ZO rats, without altering the amount of food consumed or body weight gained. In addition to improving DD, sac/val decreased aortic stiffness and reversed impairment in nitric oxide-induced vascular relaxation in ZO rats. However, sac/val had no impact on LV hypertrophy. Notably, sac/val was more effective than val in ameliorating DD. Although, hydralazine was as effective as sac/val in improving these parameters, it adversely affected LV mass index. Further, cytokine array revealed distinct effects of sac/val, including marked suppression of Notch-1 by both valsartan and sac/val, suggesting that cardiovascular protection afforded by both share some common mechanisms; however, sac/val, but not val, increased IL-4, which is increasingly recognized for its cardiovascular protection, possibly contributing, in part, to more favorable effects of sac/val over val alone in improving obesity-associated DD. CONCLUSIONS: These studies suggest that sac/val is superior to val in reversing obesity-associated DD. It is an effective drug combination to blunt progression of asymptomatic DD and vascular stiffness to HFpEF development in a preclinical model of obesity-associated prediabetes.

Effects of Angiotensin Receptor-Neprilysin Inhibitor in Arrhythmogenicity Following Left Atrial Appendage Closure in an Animal Model.

PURPOSE: Left atrial appendage (LAA) closure decreases atrial natriuretic peptide (ANP) levels, which indirectly increases the risk of arrhythmogenicity. We aimed to determine the effect of a combined angiotensin receptor-neprilysin inhibitor (ARNi) on arrhythmogenicity following LAA closure in an animal model. METHODS: Twenty-four rabbits were randomized into four groups: (1) control, (2) LAA closure (LAAC), (3) heart failure (HF)-LAAC, and (4) HF-LAAC with sacubitril/valsartan (+ARNi). HF models were developed in the HF-LAAC and HF-LAAC+ARNi groups. Epicardial LAA exclusion was performed in the LAAC, HF-LAAC, and HF-LAAC+ARNi groups. ANP levels were measured. An electrophysiological study was performed. The myocardium was harvested for histopathological analysis. RESULTS: The ANP level decreased in the LAAC group (785 ± 103 pg/mL, p = 0.03), failed to increase in the HF-LAAC group (917 ± 172 pg/mL, p = 0.3), and increased in the HF-LAAC+ARNi group (1524 ± 126 pg/mL, p < 0.01) compared to that in the control group (1014 ± 56 pg/mL). The atrial effective refractory period (ERP) was prolonged in the HF-LAAC group and restored to baseline in the HF-LAAC+ARNi group. Ventricular ERP was the longest in the HF-LAAC group. The atrial fibrillation window of vulnerability (AF WOV) was elevated in the LAAC, HF-LAAC, and HF-LAAC+ARNi groups, with the latter group having lower AF WOV than the two former groups. Ventricular fibrillation (VF) inducibility was the highest in the HF-LAAC group (51 ± 5%, p < 0.001), followed by the LAAC group (30 ± 4%, p = 0.006) and the HF-LAAC+ARNi group (25 ± 5%, p = 0.11) when compared to the control group (18 ± 4%). Atrial and ventricular fibrosis were noted in all groups except the control group. CONCLUSION: LAA closure decreased ANP, which in turn increased AF and VF inducibility. Atrial and ventricular arrhythmogenicity was suppressed by ARNi.

Myocardial Angiotensin Metabolism in End-Stage Heart Failure.

BACKGROUND: The myocardium exhibits an adaptive tissue-specific renin-angiotensin system (RAS), and local dysbalance may circumvent the desired effects of pharmacologic RAS inhibition, a mainstay of heart failure with reduced ejection fraction (HFrEF) therapy. OBJECTIVES: This study sought to investigate human myocardial tissue RAS regulation of the failing heart in the light of current therapy. METHODS: Fifty-two end-stage HFrEF patients undergoing heart transplantation (no RAS inhibitor: n = 9; angiotensin-converting enzyme [ACE] inhibitor: n = 28; angiotensin receptor blocker [ARB]: n = 8; angiotensin receptor neprilysin-inhibitor [ARNi]: n = 7) were enrolled. Myocardial angiotensin metabolites and enzymatic activities involved in the metabolism of the key angiotensin peptides angiotensin 1-8 (AngII) and Ang1-7 were determined in left ventricular samples by mass spectrometry. Circulating angiotensin concentrations were assessed for a subgroup of patients. RESULTS: AngII and Ang2-8 (AngIII) were the dominant peptides in the failing heart, while other metabolites, especially Ang1-7, were below the detection limit. Patients receiving an ARB component (i.e., ARB or ARNi) had significantly higher levels of cardiac AngII and AngIII (AngII: 242 [interquartile range (IQR): 145.7 to 409.9] fmol/g vs 63.0 [IQR: 19.9 to 124.1] fmol/g; p < 0.001; and AngIII: 87.4 [IQR: 46.5 to 165.3] fmol/g vs 23.0 [IQR: <5.0 to 59.3] fmol/g; p = 0.002). Myocardial AngII concentrations were strongly related to circulating AngII levels. Myocardial RAS enzyme regulation was independent from the class of RAS inhibitor used, particularly, a comparable myocardial neprilysin activity was observed for patients with or without ARNi. Tissue chymase, but not ACE, is the main enzyme for cardiac AngII generation, whereas AngII is metabolized to Ang1-7 by prolyl carboxypeptidase but not to ACE2. There was no trace of cardiac ACE2 activity. CONCLUSIONS: The failing heart contains considerable levels of classical RAS metabolites, whereas AngIII might be an unrecognized mediator of detrimental effects on cardiovascular structure. The results underline the importance of pharmacologic interventions reducing circulating AngII actions, yet offer room for cardiac tissue-specific RAS drugs aiming to limit myocardial AngII/AngIII peptide accumulation and actions.

The effect of neprilysin and renin inhibition on the renal dysfunction following ischemia-reperfusion injury in the rat.

The natriuretic peptide (NP) system counter-regulates the renin-angiotensin system (RAS), so enhancing the activity of natriuretic peptides (NPs) may be beneficial in conditions when RAS is activated such as ischemia-reperfusion injury (IRI). Neprilysin is the key enzyme responsible for the degradation of NPs. The effects of neprilysin inhibition or the combination of neprilysin inhibition and RAS inhibition on renal IRI-induced renal dysfunction have not been investigated yet. To investigate this, rats underwent sham surgery or bilateral IRI for 20 min. G-Als, G-Scb, and G-Als+Scb underwent similar protocol but received aliskiren (renin inhibitor), sacubitril (neprilysin inhibitor) or a combination of both pre- and post-IRI, respectively. IRI caused significant alterations in all renal functional parameters, markers of acute renal injury, pro-inflammatory and pro-fibrotic cytokines, and histological features. All these alterations were significantly attenuated in G-Als, G-Scb, and G-Als+Scb. The attenuations in the alterations in serum creatinine, creatinine clearance, and histological features were larger in G-Als+Scb compared to either G-Als or G-Scb. We conclude that RAS blockade by a renin inhibitor (aliskiren) or neprilysin inhibition by sacubitril separately led to significant attenuation in the renal IRI-induced renal dysfunction. The combination of aliskiren and sacubitril was more effective than either one alone.

Combining Neprilysin Inhibitor With AT2R Agonist Is Superior to Combination With AT1R Blocker in Providing Reno-Protection in Obese Rats.

Clinical use of the combination therapy of the neprilysin inhibitor sacubitril and angiotensin II type 1 receptor blocker valsartan is known to be associated with albuminuria. Albuminuria is both a risk factor for and an indicator of kidney injury. Earlier work from our laboratory reported that the agonist of angiotensin II type 2 receptor Compound 21 (C21) prevents proteinuria, albuminuria, and is reno-protective in obese Zucker rats fed high salt diet (HSD). Thus, we hypothesized that sacubitril/C21 combination provides superior reno-protection compared to sacubitril/valsartan. Male obese Zucker rats 10-11 weeks old were treated daily with vehicle, sacubitril + C21, or sacubitril + valsartan while fed HSD for 16 days. HSD-feeding caused kidney dysfunction, evident by significant increases in urinary protein, osteopontin, and cystatin C. HSD-feeding lowered plasma cystatin C and creatinine concentrations suggestive of hyperfiltration, which was not affected by either treatment. Unlike sacubitril/valsartan, sacubitril/C21 treatment significantly decreases proteinuria, albuminuria, the expression of nephrin, and kidney weight, independent of hyperfiltration, compared with HSD alone. Moreover, sacubitril/valsartan therapy increased plasma renin and did not prevent HSD-induced increases in renal angiotensin II, while sacubitril/C21 completely prevented these changes. Together, this study suggests that sacubitril/C21 afforded superior reno-protection compared to sacubitril/valsartan therapy in high salt-fed obese Zucker rats.

One Step Closer to Clinical Translation: Enhanced Tumor Targeting of [99mTc]Tc-DB4 and [111In]In-SG4 in Mice Treated with Entresto.

BACKGROUND: Peptide radioligands may serve as radionuclide carriers to tumor sites overexpressing their cognate receptor for diagnostic or therapeutic purposes. Treatment of mice with the neprilysin (NEP)-inhibitor phosphoramidon was previously shown to improve the metabolic stability and tumor uptake of biodegradable radiopeptides. Aiming to clinical translation of this methodology, we herein investigated the impact of the approved pill Entresto, releasing the potent NEP-inhibitor LBQ657 in vivo, on the stability and tumor uptake of two radiopeptides. METHODS: The metabolic stability of [99mTc]Tc-DB4 (DB4, N4-Pro-Gln-Arg-Tyr-Gly-Asn-Gln-Trp-Ala-Val-Gly-His-Leu-Nle-NH2) and [111In]In-SG4 (SG4, DOTA-DGlu-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH2) was tested in LBQ657/Entresto-treated mice vs. untreated controls. The uptake in gastrin-releasing peptide receptor (GRPR)-, or cholecystokinin subtype 2 receptor (CCK2R)-positive tumors respectively, was compared between LBQ657/Entresto-treated mice and untreated controls. RESULTS: LBQ657/Entresto treatment induced marked stabilization of [99mTc] Tc-DB4 and [111In]In-SG4 in peripheral mice blood, resulting in equally enhanced tumor uptake at 4 h post-injection. Accordingly, the [99mTc]Tc-DB4 uptake of 7.13 ± 1.76%IA/g in PC-3 tumors increased to 16.17 ± 0.71/17.50 ± 3.70%IA/g (LBQ657/Entresto) and the [111In]In-SG4 uptake of 3.07 ± 0.87%IA/g in A431-CCK2R(+) tumors to 8.11 ± 1.45/9.61 ± 1.70%IA/g. Findings were visualized by SPECT/CT. CONCLUSIONS: This study has shown the efficacy of Entresto to notably improve the profile of [99mTc]Tc-DB4 and [111In]In-SG4 in mice, paving the way for clinical translation of this approach.

Sacubitril/Valsartan: Neprilysin Inhibition 5 Years After PARADIGM-HF.

Sacubitril/valsartan, an angiotensin receptor-neprilysin inhibitor (ARNI), has been shown to reduce the risk of cardiovascular death or heart failure hospitalization and improve symptoms among patients with chronic heart failure with reduced ejection fraction compared to enalapril, the gold standard angiotensin-converting enzyme inhibitor. In the 5 years since the publication of the results of PARADIGM-HF, further insight has been gained into integrating a neprilysin inhibitor into a comprehensive multidrug regimen, including a renin-angiotensin aldosterone system (RAS) blocker. This paper reviews the current understanding of the effects of sacubitril/valsartan and highlights expected developments over the next 5 years, including potential new indications for use. Additionally, a practical, evidence-based approach is provided to the clinical integration of sacubitril/valsartan among patients with heart failure with reduced ejection fraction.

BNP and NT-proBNP Interpretation in the Neprilysin Inhibitor Era.

PURPOSE OF REVIEW: Describe the mechanisms that may influence change in measured natriuretic peptide levels when using the neprilysin inhibitor sacubitril to treat a patient with heart failure. RECENT FINDINGS: Prior to the introduction of the neprilysin inhibitor sacubitril as part of a chemical combination with the angiotensin receptor blocker valsartan shown to reduce mortality and heart failure hospitalizations in patients with heart failure with reduced ejection fraction, the natriuretic peptide assays for B-type natriuretic peptide (BNP) and the amino-terminal proBNP (NT-proBNP) assays were shown to have similar diagnostic accuracy to differentiate heart failure from other etiologies of shortness of breath. Sacubitril/valsartan use has been shown to result in a modest and chronic elevation of BNP while reducing levels of NT-prBNP. This review explores the potential impact of these findings on interpreting natriuretic peptide results for diagnosis and prognosis, as well as explore the challenges associated with the heterogeneity of this finding, highlighting the impact of inhibiting neprilysin, a non-specific endopeptidase with multiple target sites within BNP and other proteins. With increased uptake of sacubitril/valsartan expected in patients with heart failure, interpretation of natriuretic peptide assays becomes somewhat more complex, particularly for BNP. However, knowing a baseline steady-state concentration and using the same assay can assist with BNP interpretation for diagnosis and prognosis.

[99mTc]Tc-DB1 Mimics with Different-Length PEG Spacers: Preclinical Comparison in GRPR-Positive Models.

Background: The frequent overexpression of gastrin-releasing peptide receptors (GRPRs) in human cancers provides the rationale for delivering clinically useful radionuclides to tumor sites using peptide carriers. Radiolabeled GRPR antagonists, besides being safer for human use, have often shown higher tumor uptake and faster background clearance than agonists. We herein compared the biological profiles of the GRPR-antagonist-based radiotracers [99mTc]Tc-[N4-PEGx-DPhe6,Leu-NHEt13]BBN(6-13) (N4: 6-(carboxy)-1,4,8,11-tetraazaundecane; PEG: polyethyleneglycol): (i) [99mTc]Tc-DB7 (x = 2), (ii) [99mTc]Tc-DB13 (x = 3), and (iii) [99mTc]Tc-DB14 (x = 4), in GRPR-positive cells and animal models. The impact of in situ neprilysin (NEP)-inhibition on in vivo stability and tumor uptake was also assessed by treatment of mice with phosphoramidon (PA). Methods: The GRPR affinity of DB7/DB13/DB14 was determined in PC-3 cell membranes, and cell binding of the respective [99mTc]Tc-radioligands was assessed in PC-3 cells. Each of [99mTc]Tc-DB7, [99mTc]Tc-DB13, and [99mTc]Tc-DB14 was injected into mice without or with PA coinjection and 5 min blood samples were analyzed by HPLC. Biodistribution was conducted at 4 h postinjection (pi) in severe combined immunodeficiency disease (SCID) mice bearing PC-3 xenografts without or with PA coinjection. Results: DB7, -13, and -14 displayed single-digit nanomolar affinities for GRPR. The uptake rates of [99mTc]Tc-DB7, [99mTc]Tc-DB13, and [99mTc]Tc-DB14 in PC-3 cells was comparable and consistent with a radioantagonist profile. The radiotracers were found to be ≈70% intact in mouse blood and >94% intact after coinjection of PA. Treatment of mice with PA enhanced tumor uptake. Conclusions: The present study showed that increase of PEG-spacer length in the [99mTc]Tc-DB7-[99mTc]Tc-DB13-[99mTc]Tc-DB14 series had little effect on GRPR affinity, specific uptake in PC-3 cells, in vivo stability, or tumor uptake. A significant change in in vivo stability and tumor uptake was observed only after treatment of mice with PA, without compromising the favorably low background radioactivity levels.

Sacubitrilat reduces pro-arrhythmogenic sarcoplasmic reticulum Ca2+ leak in human ventricular cardiomyocytes of patients with end-stage heart failure.

AIMS: Inhibition of neprilysin and angiotensin II receptor by sacubitril/valsartan (Val) (LCZ696) reduces mortality in heart failure (HF) patients compared with sole inhibition of renin-angiotensin system. Beneficial effects of increased natriuretic peptide levels upon neprilysin inhibition have been proposed, whereas direct effects of sacubitrilat (Sac) (LBQ657) on myocardial Ca2+ cycling remain elusive. METHODS AND RESULTS: Confocal microscopy (Fluo-4 AM) was used to investigate pro-arrhythmogenic sarcoplasmic reticulum (SR) Ca2+ leak in freshly isolated murine and human ventricular cardiomyocytes (CMs) upon Sac (40 µmol/L)/Val (13 µmol/L) treatment. The concentrations of Sac and Val equalled plasma concentrations of LCZ696 treatment used in PARADIGM-HF trial. Epifluorescence microscopy measurements (Fura-2 AM) were performed to investigate effects on systolic Ca2+ release, SR Ca2+ load, and Ca2+ -transient kinetics in freshly isolated murine ventricular CMs. The impact of Sac on myocardial contractility was evaluated using in toto-isolated, isometrically twitching ventricular trabeculae from human hearts with end-stage HF. Under basal conditions, the combination of Sac/Val did not influence diastolic Ca2+ -spark frequency (CaSpF) nor pro-arrhythmogenic SR Ca2 leak in isolated murine ventricular CMs (n CMs/hearts = 80/7 vs. 100/7, P = 0.91/0.99). In contrast, Sac/Val treatment reduced CaSpF by 35 ± 9% and SR Ca2+ leak by 45 ± 9% in CMs put under catecholaminergic stress (isoproterenol 30 nmol/L, n = 81/7 vs. 62/7, P < 0.001 each). This could be attributed to Sac, as sole Sac treatment also reduced both parameters by similar degrees (reduction of CaSpF by 57 ± 7% and SR Ca2+ leak by 76 ± 5%; n = 101/4 vs. 108/4, P < 0.01 each), whereas sole Val treatment did not. Systolic Ca2+ release, SR Ca2+ load, and Ca2+ -transient kinetics including SERCA activity (kSERCA ) were not compromised by Sac in isolated murine CMs (n = 41/6 vs. 39/6). Importantly, the combination of Sac/Val and Sac alone also reduced diastolic CaSpF and SR Ca2+ leak (reduction by 74 ± 7%) in human left ventricular CMs from patients with end-stage HF (n = 71/8 vs. 78/8, P < 0.05 each). Myocardial contractility of human ventricular trabeculae was not acutely affected by Sac treatment as the developed force remained unchanged over a time course of 30 min (n trabeculae/hearts = 3/3 vs. 4/3). CONCLUSION: This study demonstrates that neprilysin inhibitor Sac directly improves Ca2+ homeostasis in human end-stage HF by reducing pro-arrhythmogenic SR Ca2+ leak without acutely affecting systolic Ca2+ release and inotropy. These effects might contribute to the mortality benefits observed in the PARADIGM-HF trial.