Angiotensin receptor–neprilysin inhibitor (ARNi): Clinical studies on a new class of drugs

Protective effect of novel angiotensin receptor neprilysin inhibitor S086 on target organ injury in spontaneously hypertensive rats

BACKGROUND

Hypertension is a clinical syndrome characterized by elevated systemic arterial blood pressure associated with injury to the heart, kidney, brain, and other organs. Angiotensin receptor neprilysin inhibitors (ARNi), including angiotensin receptor blockers (ARBs) and neprilysin inhibitors (NEPi), have been shown to be safe and effective at reducing blood pressure and alleviating development of target organ injury. This study was used to develop S086 as a novel ARNi and conducted preclinical studies in animal models to evaluate the protective effects of S086 on target organs.

METHODS

This study used a 14-month-old spontaneously hypertensive rat (SHR) model to evaluate the protective effects of S086 on the cardiovascular system and organs such as heart and kidney by blood pressure monitoring, urine and blood examination, pathological examination, and immunological index detection.

RESULTS

After administering S086 orally to the SHR, their blood pressure and levels of renal injury indicators such as serum creatinine and urinary microalbumin were reduced, and myocardial cell necrosis and cardiac fibrosis of the heart were significantly improved. In addition, there were also significantly improvements in the histological lesions of blood vessels and the kidneys.

CONCLUSIONS

The findings showed that S086 effectively reduced the blood pressure of SHR and had effects on alleviating development of heart, blood vessels and kidney.

Reactive Oxygen Species Induced Pathways in Heart Failure Pathogenesis and Potential Therapeutic Strategies

With respect to structural and functional cardiac disorders, heart failure (HF) is divided into HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF). Oxidative stress contributes to the development of both HFrEF and HFpEF. Identification of a broad spectrum of reactive oxygen species (ROS)-induced pathways in preclinical models has provided new insights about the importance of ROS in HFrEF and HFpEF development. While current treatment strategies mostly concern neuroendocrine inhibition, recent data on ROS-induced metabolic pathways in cardiomyocytes may offer additional treatment strategies and targets for both of the HF forms. The purpose of this article is to summarize the results achieved in the fields of: (1) ROS importance in HFrEF and HFpEF pathophysiology, and (2) treatments for inhibiting ROS-induced pathways in HFrEF and HFpEF patients. ROS-producing pathways in cardiomyocytes, ROS-activated pathways in different HF forms, and treatment options to inhibit their action are also discussed.

Integrating High-Sensitivity Troponin T and Sacubitril/Valsartan Treatment in HFpEF: The PARAGON-HF Trial

OBJECTIVES

This study examined the relationship among high-sensitivity troponin-T (hs-TnT), outcomes, and treatment with sacubitril/valsartan in patients with heart failure (HF) and preserved ejection fraction (HFpEF).

BACKGROUND

hs-TnT is a marker of myocardial injury in HF.

METHODS

The PARAGON-HF trial randomized 4,796 patients with HFpEF to sacubitril/valsartan or valsartan. We compared the risk of the composite outcome of cardiovascular death (CVD) and total HF hospitalization (HHF) according to hs-TnT. We also assessed the effect of allocated treatment on hs-TnT.

RESULTS

hs-TnT was available in 1,141 patients (24%) at run-in (median value: 17 ng/L) and 1,260 (26%) at randomization, with 58.3% having hs-TnT >14 ng/L (upper limit of normal). During a median follow-up of 34 months, there were 393 outcome events (82 CVD, 311 HHF). Adjusting for demographics, comorbidities, left ventricular ejection fraction (LVEF), and N-terminal pro B-type natriuretic peptide (NT-proBNP), log-hs-TnT at randomization was an independent predictor of the composite outcome (HR: 1.38; 95% CI: 1.19-1.59; P < 0.001). Compared with valsartan, sacubitril/valsartan significantly reduced hs-TnT by 9% at week 16 (P < 0.001). Patients whose hs-TnT decreased from randomization to 16 weeks to at or below the median value of 17 ng/L subsequently had a lower risk of CVD/HHF compared with those with persistently elevated hs-TnT (P = 0.046). Patients with higher baseline hs-TnT (>17 ng/L) appeared to have a greater benefit from sacubitril/valsartan treatment when accounting for other potential effect modifiers (P interaction = 0.07).

CONCLUSIONS

Higher baseline hs-TnT was associated with increased risk of CVD/HHF, whereas hs-TnT decrease at 16 weeks led to lower subsequent risk of CVD/HHF compared with those who had persistently elevated values. Sacubitril/valsartan significantly reduced hs-TnT compared with valsartan. hs-TnT may be helpful in identifying patients with HFpEF who are more likely to benefit from sacubitril/valsartan.

Rationale for and Practical Use of Sacubitril/Valsartan in the Patient's Journey with Heart Failure and Reduced Ejection Fraction

Sacubitril with valsartan (sacubitril/valsartan) is a relatively novel compound that has become a milestone in the treatment of patients with chronic heart failure (HF) with reduced ejection fraction (HFrEF) in the last decade. Contemporary data suggest that sacubitril/valsartan is associated with improved outcomes compared with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, and has a greater beneficial effect on myocardial reverse remodelling. Additionally, two recent trials have shown that sacubitril/valsartan is well-tolerated even in the acute HF setting, thus enabling a continuum of use in the patient's journey with HFrEF. This article summarises available data on the effectiveness and tolerability of sacubitril/valsartan in patients with HFrEF, and provides the clinician with practical insights to facilitate the use of this drug in every setting, with an emphasis on acute HF, hypotension, electrolyte imbalance and renal insufficiency.

Neprilysin Inhibitors: Filling a Gap in Heart Failure Management, Albeit Amidst Controversy and at a Significant Cost

Dual angiotensin and neprilysin inhibition using the combination drug sacubitril-valsartan has ushered in a new era in the treatment of heart failure (HF). The randomized controlled PARADIGM-HF trial, which randomized 8399 patients with HF to enalapril or sacubitril-valsartan, showed a 20% reduction in mortality and HF hospitalization with the new drug. This has been heralded as a step toward filling a crucial gap in HF management by providing strong evidence that combined inhibition of the angiotensin receptor and neprilysin is superior to inhibition of the renin-angiotensin system alone in stable patients with chronic HF as it negates the deleterious effects of angiotensin while concomitantly augmenting the beneficial effects of the endogenous natriuretic peptide system. This new therapy is costly, and other confirmatory studies have been lacking for over 2 years since its approval by major regulatory authorities. As such, controversy and heated discussions have amassed, as has detailed information from a plethora of secondary analyses of this pivotal trial about the pros and cons of this promising new therapeutic strategy in HF management. The aim of this review was to provide a critical assessment of all these aspects.

Sacubitril/valsartan therapeutic strategy in HFpEF: Clinical insights and perspectives

Sacubitril/valsartan represents the first of a new class of drugs able to act as a neprilysin inhibitor and as an angiotensin receptor blocker. This double inhibition has the advantage of concomitantly blocking a pro-fibrotic/pro-hypertrophic mechanism (angiotensin receptor blocker component) while stimulating an anti-fibrotic/anti-hypertrophic mechanism (neprilysin inhibitor component). Furthermore, the novel drug has natriuretic and diuretic properties, better preserves renal function, provides better blood pressure control as compared to renin angiotensin system inhibitors, and improves ventricular-arterial coupling. Consequently, sacubitril/valsartan provides greater target organ protection than angiotensin receptor blocker therapy alone, including cardiac, vascular, and renal protection. Up to now, this drug does not have an indication in patients with heart failure with preserved ejection fraction (HFpEF). However, its complex mechanism of action and previous experimental and clinical data seem to suggest its possible success in HFpEF. In this review we highlight and discuss the rationale, clinical insights, and perspectives behind the use of sacubitril/valsartan in HFpEF, specifically referring to its possible efficacy in pathophysiologic mechanisms, such as myocardial hypertrophy, fibrosis, and ischemia, renal dysfunction, impaired ventricular-arterial coupling, which are all tightly related to elevated left ventricular end diastolic pressure, a common hallmark for this multifaceted syndrome.

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.