Aprocitentan, a dual endothelin-1 (ET-1) antagonist for treating resistant hypertension: Mechanism of action and therapeutic potential

Research trends and performance of endothelin A receptor antagonist in kidney care: a bibliometric analysis

BACKGROUND

Endothelin A receptor antagonists (ERAs) have emerged as pivotal therapeutic agents in managing pulmonary hypertension (PH) and various kidney disorders, including chronic kidney disease (CKD) and proteinuric glomerular diseases such as IgA nephropathy (IgAN) and focal segmental glomerulosclerosis (FSGS). Although initially developed for pulmonary applications, recent research has highlighted their renoprotective effects, expanding their role in nephrology. This study presents a comprehensive bibliometric analysis of global research trends, key contributors, and emerging applications of ERAs in kidney care over the past three decades.

METHODS

A bibliometric analysis was performed using the Science Citation Index Expanded database (1992-2023). Relevant kidney-related publications were identified through specific keyword searches. Author performance was assessed using the Y-index.

RESULTS

ERA-related research has shown significant growth, particularly in nephrology. The United States and the University of Groningen lead in publication volume and international collaborations, with H.J.L. Heerspink emerging as a key contributor. While PH remains the dominant research focus, nephrology applications are rapidly increasing, particularly in CKD, diabetic nephropathy (DN), and glomerular diseases. A major milestone was the accelerated FDA approval of sparsentan for IgAN in 2023, followed by full approval in 2024 based on confirmatory efficacy data. However, challenges such as fluid retention and cardiovascular risks remain, necessitating further investigation into optimized ERA therapies, including combination strategies with SGLT2 inhibitors.

CONCLUSIONS

The expanding role of ERAs in nephrology underscores their potential in treating proteinuric kidney diseases. Ongoing international collaborations are advancing research on ERA safety, efficacy, and novel therapeutic strategies, supporting their broader clinical application.

Novel drugs approved by the EMA, the FDA and the MHRA in 2024: A year in review

In the past year, the European Medicines Agency (EMA), the Food and Drug Administration (FDA) and the Medicines and Healthcare Products Regulatory Agency (MHRA) authorised 53 novel drugs. While the 2024 harvest is not as rich as in 2023, when 70 new chemical entities were approved, the number of 'orphan' drug authorisations in 2024 (21) is similar to that of 2023 (24), illustrating the dynamic development of therapeutics in areas of unmet need. The 2024 approvals of novel protein therapeutics (15) and advanced therapy medicinal products (ATMPs, 6) indicate a sustained trend also noticeable in the 2023 new drugs reviewed in this journal last year (16 and 11, respectively). Clearly, the most striking characteristic of the 2024 drug yield is the creative pharmacological design, which allows these medicines to employ a novel approach to target a disease. Some notable examples are the first drug successfully using a 'dock-and-block' mechanism of inhibition (zenocutuzumab), the first approved drug for schizophrenia designed as an agonist of M1/M4 muscarinic receptors (xanomeline), the first biparatopic antibody (zanidatamab), binding two distinct epitopes of the same molecule, the first haemophilia therapy that instead of relying on external supplementation of clotting factors, restores Factor Xa activity by inhibiting TFPI (marstacimab), or the first ever authorised direct telomerase inhibitor (imetelstat) that reprogrammes the oncogenic drive of tumour cells. In addition, an impressive percentage of novel drugs were first in class (28 out of 53 or 53% of the total) and a substantial number can be considered disease agnostic, indicating the possibility of future approved extensions of their use for additional indications. The 2024 harvest demonstrates the therapeutic potential of innovative pharmacological design, which allows the effective targeting of intractable disorders and addresses crucial, unmet therapeutic needs.

Transpulmonary Plasma Endothelin-1 Arterial:Venous Ratio Differentiates Survivors from Non-Survivors in Critically Ill Patients with COVID-19-Induced Acute Respiratory Distress Syndrome

Endothelin-1 (ET-1) is a potent vasoconstrictor produced by endothelial cells and cleared from circulating blood mainly in the pulmonary vasculature. In a healthy pulmonary circulation, the rate of local production of ET-1 is less than its rate of clearance. In the present study, we aimed to investigate whether the abnormal pulmonary circulatory handling of ET-1 relates to poor clinical outcomes in patients with coronavirus disease 2019 (COVID-19)-induced acute respiratory distress syndrome (ARDS). To this end, central venous and systemic arterial ET-1 plasma levels were simultaneously measured on Days 1 and 3 following ICU admission in mechanically ventilated COVID-19 patients with ARDS (COVID-19 ARDS, N = 18). Central venous and systemic arterial ET-1 plasma levels were also measured in two distinct SARS-CoV-2-negative mechanically ventilated critically ill patient groups, matched for age, sex, and critical illness severity, with ARDS (non-COVID-19 ARDS, N = 14) or without ARDS (non-COVID-19 non-ARDS, N = 20). Upon ICU admission, COVID-19-induced ARDS patients had higher systemic arterial and central venous ET-1 levels compared to the non-COVID-19 ARDS and non-COVID-19 non-ARDS patients (p < 0.05), yet a normal systemic arterial:central venous (A:V) ET-1 ratio [0.63 (0.49-1.02)], suggesting that pulmonary ET-1 clearance is intact in these patients. On the other hand, the non-COVID-19 ARDS patients demonstrated abnormal ET-1 handling [A:V ET-1 ratio 1.06 (0.93-1.20)], while the non-COVID-19 non-ARDS group showed normal ET-1 handling [0.79 (0.52-1.11)]. On Day 3, the A:V ratio in all three groups was <1. When the COVID-19 ARDS patients were divided based on 28-day ICU mortality, while their systemic arterial and central venous levels did not differ, the A:V ET-1 ratio was statistically significantly higher upon ICU admission in the non-survivors [0.95 (0.78-1.34)] compared to the survivors [0.57 (0.48-0.92), p = 0.027]. Our results highlight the potential importance of ET-1 as both a biomarker and a therapeutic target in critically ill COVID-19 patients. The elevated A:V ET-1 ratio in non-survivors suggests that the early disruption of pulmonary ET-1 handling may be a key marker of poor prognosis.

A review of novel endothelin antagonists and overview of non-steroidal mineralocorticoid antagonists for treating resistant hypertension: An update

Several agents are emerging from five different novel classes of antihypertensive medications. We will focus on endothelin antagonists and non-steroidal mineralocorticoid receptor antagonists. While several agents exist in this later class, only a couple have demonstrated superior efficacy in resistant hypertension management. Endothelin receptor antagonists are effective therapy for primary and resistant hypertension, but they are not widely used. This is due to side effects demonstrated in large clinical trials, specifically increased peripheral edema and worsening heart failure in some cases, as well as the availability of many alternative agents to manage blood pressure effectively. However, the relationship between endothelin and its close ties to hypertension is evolving. Recent pre-clinical work explores new applications of more selective endothelin receptor antagonists. They suggest that specific subtypes of hypertension may benefit more from endothelin receptor blockade than simply those with primary hypertension. We review this topic and other related data. Lastly, we also provide a brief overview of non-steroidal mineralocorticoid receptor antagonists as some in the class show promise as antihypertensive agents.

How New Developments in Pharmacology Receptor Theory Are Changing (Our Understanding of) Hypertension Therapy

BACKGROUND

Many hypertension therapeutics were developed prior to major advances in drug receptor theory. Moreover, newer drugs may take advantage of some of the newly understood modalities of receptor function.

GOAL

The goal of this review is to provide an up-to-date summary of drug receptor theory. This is followed by a discussion of the drug classes recognized for treating hypertension to which new concepts in receptor theory apply.

RESULTS

We raise ideas for mechanisms of potential new antihypertensive drugs and whether they may take advantage of new theories in drug-receptor interaction.

Bosentan and Pulmonary Hypertension Caused by COVID-19: A Pilot Randomized Double-blind Clinical Study

INTRODUCTION/OBJECTIVE

Coronavirus disease 2019 (COVID-19) has been the biggest pandemic in history, with severe complications, such as acute respiratory distress syndrome and pulmonary hypertension (PH). An endothelin-1 (ET-1) receptor antagonist, such as bosentan, may be beneficial in treating elevated ET-1 levels. Hence, our study aimed to evaluate the therapeutic effects of bosentan in patients with COVID-19-induced PH.

METHODS

A single-centre, randomized, double-blind study involving 72 participants was carried out; 36 received bosentan and the other 36 received a placebo. Pulmonary arterial pressure, tricuspid valve pressure gradient, and right atrial pressure were measured using echocardiography. The Cox proportional hazards regression model was used to investigate the impact of bosentan and patients' age on mortality during a 6-month follow-up period.

RESULTS

In-hospital mortality was significantly lower in the case group (13%) compared with the control group (33.3%) (P=0.003). Additionally, bosentan improved echocardiographic parameters, such as systolic pulmonary artery pressure and tricuspid regurgitation gradient (P=0.011 and P=0.003, respectively). Bosentan use was a significant predictor of long-term mortality rates for 600 days [age-adjusted hazard ratio of 5.24 (95% CI 1.34 to 20.46)].

CONCLUSION

This study provided a mixed perspective on the use of bosentan therapy in patients with COVID-19-related PH. Bosentan effectively reduced in-hospital mortality and improved echocardiographic measures. However, the treatment group showed an increased requirement for supplemental oxygen therapy and long-term mortality. Further studies with larger sample sizes are necessary to elucidate the effects of bosentan in PH following COVID-19.