Endothelin Receptor Antagonist Research Articles

Targeting the endothelium by combining endothelin-1 antagonism and SGLT-2 inhibition: better together?

Endothelin A and B receptors, together with sodium-glucose cotransporter-2 (SGLT-2) channels are important targets in improving endothelial function and intervention with inhibitors has been the subject of multiple mechanistic and clinical outcome trials over recent years. Notable successes include the treatment of pulmonary hypertension with endothelin receptor antagonists, and the treatment of heart failure and chronic kidney disease with SGLT-2 inhibitors. With distinct and complementary mechanisms, in this review, we explore the logic of combination therapy for a number of diseases which have endothelial dysfunction at their heart.

US commercial health plan coverage dynamics in pulmonary arterial hypertension therapies.

Health plan coverage is central to patient access to care, especially for rare, chronic diseases. For specialty drugs, coverage varies, resulting in barriers to access. Pulmonary arterial hypertension (PAH) is a rare, progressive, and fatal disease. Guidelines suggest starting or rapidly escalating to combination therapy with drugs of differing classes (phosphodiesterase 5 inhibitors [PDE5is], soluble guanylate cyclase stimulators [sGC stimulators], endothelin receptor antagonists [ERAs], and prostacyclin pathway agents [PPAs]). To assess the variation in commercial health plan coverage for PAH treatments and how coverage has evolved. To examine the frequency of coverage updates and evidence cited in plan policies. We used the Tufts Medical Center Specialty Drug Evidence and Coverage database, which includes publicly available specialty drug coverage policies. Overall, and at the drug and treatment class level, we identified plan-imposed coverage restrictions beyond the drug's US Food and Drug Administration label, including step therapy protocols, clinical restrictions (eg, disease severity), and prescriber specialty requirements. We analyzed variation in coverage restrictiveness and how coverage has changed over time. We determined how often plans update their policies. Finally, we categorized the cited evidence into 6 different types. Results reflected plan coverage policies for 13 PAH drugs active between August 2017 and August 2022 and issued by 17 large US commercial health plans, representing 70% of covered lives. Coverage restrictions varied mainly by step therapy protocols and prescriber restrictions. Seven plans had step therapy protocols for most drugs, 9 for at least one drug, and 1 had none. Ten plans required specialist (cardiologist or pulmonologist) prescribing for at least one drug, and 7 did not. Coverage restrictions increased over time: the proportion of policies with at least 1 restriction increased from 38% to 73%, and the proportion with step therapy protocols increased from 29% to 46%, with generics as the most common step. The proportion of policies with step therapy protocols increased for every therapy class with generic availability: 18% to 59% for ERAs, 33% to 77% for PDE5is, and 33% to 43% for PPAs. The proportion of policies with prescriber requirements increased from 24% to 48%. Plans updated their policies 58% of the time annually and most often cited the 2019 CHEST clinical guidelines, followed by randomized controlled trials. Plan use of coverage restrictions for PAH therapies increased over time and varied across both drugs and plans. Inconsistency among health plans may complicate patient access and reduce the proportion who can persist on PAH treatments.

Is endothelin targeting finally ready for prime time?

The endothelin family of peptides has long been recognized as a physiological regulator of diverse biological functions and mechanistically involved in various disease states, encompassing, among others, the cardiovascular system, the kidney, and the nervous system. Pharmacological blockade of the endothelin system, however, has encountered strong obstacles in its entry into the clinical mainstream, having obtained only a few proven indications until recently. This translational gap has been attributable predominantly to the relevant side effects associated with endothelin receptor antagonism (ERA), particularly fluid retention. Of recent, however, an expanding understanding of the pathophysiological processes involving endothelin, in conjunction with the development of new antagonists of endothelin receptors or adjustment of their doses, has driven a flourish of new clinical trials. The favorable results of some of them have extended the proven indications for ET targeting to a variety of clinical conditions, including resistant arterial hypertension and glomerulopathies. In addition, on the ground of strong preclinical evidence, other studies are ongoing to test the potential benefits of ERA in combination with other treatments, such as sodium-glucose co-transporter 2 inhibition in fluid retentive states or anti-cancer therapies in solid tumors. Furthermore, antibodies providing long-term blockade of endothelin receptors are under testing to overcome the short half-life of most small molecule endothelin antagonists. These efforts may yet bring new life to the translation of endothelin targeting strategies in clinical practice.

#362 Dosing low, winning high: unlocking the promise of endothelin antagonism for the treatment of CKD in the zibotentan/dapagliflozin ZENITH trials

Abstract Background and Aims The Phase 2b ZENITH-CKD trial demonstrated that combined treatment with the endothelin A receptor (ETAR) antagonist zibotentan and the sodium-glucose co-transporter-2 inhibitor (SGLT2i) dapagliflozin yields a robust and significant reduction in albuminuria in individuals with chronic kidney disease (CKD), compared to dapagliflozin treatment alone [1]. This is hypothesized to translate into a significant reduction of kidney function decline and may further confer cardiometabolic benefits including reducing blood pressure, LDL cholesterol and (in type 2 diabetes) HbA1c in the ongoing Phase 3 ZENITH High Proteinuria trial. The usage of ETAR antagonists has until now been limited by the class effect of fluid retention, which is associated with an increased risk of heart failure in the at-risk CKD population. Zibotentan has previously been investigated at 10 mg per day in Phase 3 for the treatment of prostate cancer. Method Model-Informed Drug Development (MIDD) was integrated with clinical pharmacology data to develop the dose strategy for both ZENITH trials. A low-dose strategy was selected considering the increased plasma exposure of zibotentan in kidney impairment. The Phase 2b dose steps were selected based on an exposure response model for the efficacy marker urinary albumin to creatinine ratio (uACR) and were supported using clinical trial simulations. The dose strategy for Phase 3 was defined based on a combined analysis of ZENITH-CKD results for both efficacy and tolerability: efficacy (uACR reduction on top of dapagliflozin) was analysed with a Dose-Response Mixed Model for Repeated Measures, and tolerability (fluid retention events, defined as a combination of specified body weight and BNP increase) was evaluated with Kaplan Meier analyses. Results Zibotentan doses of 0.25 mg and 1.5 mg (in a first, discontinued study part also 5 mg), in combination with dapagliflozin 10 mg, were selected for ZENITH-CKD. Clinical trial simulations indicated that inclusion of the low dose of 0.25 mg was crucial to characterise the dose-response relationship. Dose-uACR response modelling of ZENITH-CKD data predicted a zibotentan dose of 0.75 mg to result in a mean uACR reduction of around 25% in addition to the reduction with dapagliflozin. A post-hoc regression analysis of uACR mean changes from baseline, stratified by dose, showed a trend towards lower uACR reduction with higher eGFR levels. Kaplan-Meier analyses of the fluid retention risk in different eGFR subgroups indicated that the fluid retention risk increased with increasing zibotentan dose for eGFR levels <45 mL/min/1.73 m2, while for higher eGFR levels, no differences were observed between treatments with dapagliflozin alone and added zibotentan 0.25 mg or 1.5 mg. Therefore, a kidney-function based zibotentan dose strategy was selected for the ZENITH High Proteinuria trial: Combined zibotentan/dapagliflozin is being compared against dapagliflozin alone; within the combination treatment arm, 0.25 mg zibotentan is selected for participants with baseline eGFR levels <45 mL/min/1.73 m2, and 0.75 mg is selected for higher eGFR level, with a tolerance eGFR window for participants whose eGFR declines below this cut-off, and with the possibility to reduce the dose to 0.25 mg in case of tolerability findings. Conclusion The favourable benefit/risk profile that was demonstrated for combined zibotentan/dapagliflozin in ZENITH-CKD was enabled by the zibotentan low-dose strategy. The wide dose ranging and MIDD further enabled selection of a kidney-function based zibotentan dosing strategy for ZENITH High Proteinuria which is designed to further balance benefit/risk. The low-dose zibotentan strategy and the combination with dapagliflozin opened for the first time a therapeutic window for ETAR antagonists, with the potential to redefine their value for the treatment of CKD. This work was sponsored by AstraZeneca.

#2661 High albuminuria in CKD: prevalence and characteristics in a real-world clinical setting

Abstract Background and Aims Chronic kidney disease (CKD) is estimated to affect 1 in 10 adults globally. CKD is associated with increased morbidity, mortality and decreased quality of life, and places a financial burden on the healthcare system. Furthermore, persistently high albuminuria is associated with an especially high risk of renal and cardiovascular complications in patients with CKD. With recent advances in therapeutic approaches for CKD management, both with sodium–glucose co-transporter-2 inhibitors (SGLT2i) and endothelin receptor antagonists as add-on to renin–angiotensin system blockade, it is important to highlight patients with persistent urine albumin-creatinine ratio (UACR; ≥700 mg/g). In patients with UACR >700 mg/g, a novel and highly selective endothelin receptor A antagonist (zibotentan) plus the SGLT2i dapagliflozin significantly reduced albuminuria versus dapagliflozin plus placebo (ZENITH-CKD trial). Hence, it is important to understand the prevalence and characteristics of patients with CKD and high albuminuria in a real-world clinical setting. Methods We used a large USA claims database (Optum's de-identified Clinformatics® Data Mart Database [CDM]) to identify patients aged ≥18 years with a CKD diagnosis and a UACR measurement ≥200 mg/g. Patients were indexed on 1st January 2022 and grouped into two UACR groups: ≥700UACR group (≥700 mg/g) and <700UACR group (200–699 mg/g). Continuous variables were calculated as medians with interquartile range (IQR). Baseline characteristics and comorbidities included age, sex, median UACR, median estimated glomerular filtration rate (eGFR) and a history of heart failure. Results Of 53,306 patients with CKD and UACR ≥200 mg/g, 22,504 (42%) were in the ≥700UACR group and 30,802 (58%) in the <700UACR group (Fig. 1). Patients were more frequently men in both groups (57%). Median UACR was 1459 mg/g (IQR 977–2473) in the ≥700UACR group and 341 mg/g (IQR 256–474) in the <700UACR group. Patients in the ≥700UACR group were slightly younger (72 vs 74 years), had a higher frequency of heart failure (42% vs 34%) and lower eGFR (37 mL/min/1.73 m2 [IQR 21–55] vs 49 mL/min/1.73 m2 [IQR 34–67]) compared to the <700UACR group. Conclusions In this contemporary study of patients with albuminuric CKD, more than 4 out of 10 had UACR levels ≥700 mg/g. These patients were slightly younger, had more severe CKD, and greater prevalence of cardiorenal disease compared to those with UACR 200–699 mg/g. Patients with UACR levels ≥700 mg/g have an urgent need for improved risk management.

#1568 Cardiometabolic benefits of low dose zibotentan and dapagliflozin 10 mg in the ZENITH-CKD study

Abstract Background and Aims Positive effects of endothelin receptor antagonists on blood pressure and urinary albumin excretion have been well described, although their use in a wider population of patients with chronic kidney disease with increased cardiovascular risk has been limited by potential fluid retention. Here we present the effects of low dose zibotentan in combination with dapagliflozin on a range of cardiometabolic risk factors. Method In a post-hoc analysis of the ZENITH-CKD trial, a randomized, double-blind, active-controlled trial conducted in 170 clinical sites in 19 countries, adults with a urinary albumin-creatinine ratio (UACR) of 150 to 5000 mg/g and eGFR ≥20 mL/min/1.73 m2 not on SGLT2i were randomized to zibotentan/dapagliflozin, 0.25 mg/10 mg, zibotentan/dapagliflozin, 1.5 mg/10 mg, or placebo/dapagliflozin 10 mg. Effects on fluid retention events, defined as body weight increase from baseline >3% (of which at least 2.5% from total body water) or BNP increase >100% to >200 pg/mL without atrial fibrillation or 100% increase to >400 pg/mL with atrial fibrillation were assessed (NCT04724837). Results Data from the full analysis set is presented including 91 participants treated with 0.25 mg zibotentan and 10 mg dapagliflozin, and 177 participants treated with 10 mg dapagliflozin and placebo. UACR reduction for 0.25 mg zibotentan and 10 mg dapagliflozin was −47.7%, for 10 mg dapagliflozin alone it was −28.3%, making an adjusted mean difference for the combination versus dapagliflozin alone of −27.0%. Cardiometabolic markers are shown in the table. Conclusion In the ZENITH-CKD study zibotentan used at low dose combined with dapagliflozin had incremental effects versus dapagliflozin alone on a range of cardiometabolic risk markers including blood pressure, LDL cholesterol, HbA1c and uric acid, without a significant increase in fluid retention.

Portopulmonary hypertension: peculiarities of diagnosis and treatment

Portopulmonary hypertension is defined as the development of pulmonary hypertension secondary to portal one. Its exact prevalence is difficult to determine due to the lack of routine screening in patients with portal hypertension. Hemodynamic changes associated with portal hypertension, including the hyperdynamic state, portosystemic shunts, and splanchnic vasodilation, cause significant disturbances in the pulmonary vasculature and play a key role in the pathogenesis of the disease. Without treatment, portopulmonary hypertension leads to progressive right ventricular failure with a poor prognosis. Although Doppler echocardiography is the best initial screening tool for symptomatic patients and candidates for liver transplant, right heart catheterization remains the gold standard for disease diagnosis. Treatment of patients with portopulmonary hypertension is aimed at improving cardiac function, reducing pulmonary vascular resistance, and optimizing functional capacity. Pulmonary hypertension-specific therapy, which includes prostacyclin and its receptor agonists, endothelin receptor antagonists, phosphodiesterase inhibitors, and guanylate cyclase stimulators, plays a key role in the treatment of patients with portopulmonary hypertension. Small uncontrolled and recent single randomized controlled trials have reported promising results of vasodilator therapy in terms of clinical and hemodynamic improvement in patients, allowing certain patients to undergo liver transplantation. This review discusses the epidemiology, approach to diagnosis and treatment of patients with portopulmonary hypertension. We used MEDLINE database on the PubMed platform and the Cochrane library to search for literature sources using the keywords: portopulmonary hypertension, portal hypertension, pulmonary hypertension, liver cirrhosis, pulmonary complications.

PULMONARY HYPERTENSION AND CONGENITAL HEART DISEASE: THE CLINIC BEYOND THE EVIDENCE

Abstract Eisenmenger syndrome (ES), first described by Victor Eisenmenger, was defined by Paul Wood in pathophysiologic terms as “pulmonary hypertension (PH) at systemic level, caused by a high pulmonary vascular resistance (PVR), with reversed or bidirectional shunt at aorto–pulmonary, ventricular, or atrial level.” It represents the most severe hemodynamic phenotype of pulmonary arterial hypertension (PAH) in association with congenital heart disease (CHD) and develops in the presence of large, unrepaired atrial or ventricular septal defects, arterial shunts, or complex forms of CHD. Although therapeutic management has rapidly advanced in recent years, these patients were not included in randomized controlled trials for specific pulmonary arterial hypertension drugs, except for bosentan. However, in clinical practice we apply treatment strategies combining drugs targeting multiple pathobiological pathways. The clinical case we describe is that of a 44–year–old patient, suffering from Down syndrome, with ES due to subaortic VSD and a a patency of Botallo duct, followed in our PH clinic of the "Ruggi D‘Aragona" University Hospital for about 9 years. The patient, on dual therapy with Macitentan 10 mg and Sildenafil 60 mg, was in the intermediate–high risk class, stationary. During the last two checks, there was a progressive worsening of the hemodynamic parameters, walking distance of only 100 meters, with SpO2 at baseline 90% and desaturation during the 6mwt. On cardiac color Doppler ultrasound evidence of TAPSE 18 mm, PAPS 100 mmHg, RAA 20 cm²; TAPSE/PAPS 0.18. The patient presented in WHO class 3. The only RCTs currently available concern the use of bosentan, but in clinical practice, initial monotherapy with an endothelin receptor antagonist or a phosphodiesterase type 5 inhibitor for symptomatic patients is proposed. Reassess and consider escalation to a double combination therapy in case of clinical worsening or inadequate clinical response. Consider uptitration with the addition of prostanoids when inadequate response and timely assess the eligibility for transplantation. For our patient therefore, in consideration of the impossibility of surgery, although there is little evidence on prospective observational studies based on cohorts of a few patients, we added selexipag 200 ug x 2/day to titrate therapy.This case opens the door to still unclear scenarios in which unfortunately the only weapon available remains the clinician‘s judgment and experience.

A CASE OF PULMONARY HYPERTENSION ASSOCIATED WITH MYELOFIBROSIS: THERAPEUTICAL CHALLENGES FROM ACUTE TO CHRONIC SETTING

Abstract A 85–year–old female was transferred to our ICCU for acute heart failure from one of our spoke hospitals. The patient had a long history of chronic myelofibrosis, treated with fedratinib as a second–line agent after ruxolitinib failure. During a recent hospital admission, transthoracic echocardiography already showed signs of severe pulmonary hypertension (PH) with right ventricular (RV) dysfunction, so diuretic was started. On admission the patient presented showed consistent with acute on chronic kidney injury (serum Cr 3.2 mg/dl), stable anemia (Hb 9.2 mg/dl) and markedly elevated Nt–proBNP. A pulmonary CT–scan excluded acute pulmonary embolism and lung parenchymal alterations, with a clear dilation of main pulmonary artery. Transthoracic echocardiography (figure 1) confirmed precapillary PH phenotype diagnosis. Electrocardiogram (figure 2) showed sinus rhythm; incomplete RBBB, T wave inversion in V2 to V4. The patient was initially treated with high dose furosemide, low flow oxygen; but later she needed multiple cycles of inotropes, vasopressors and combined diuretic therapy (metolazone and acetazolamide) to stabilize the clinical setting. The patient also experienced episodes of paroxysmal high ventricular rate atrial flutter. After resolution of volume overload, a right heart catheterization was performed and findings were consistent with severe precapillary pulmonary hypertension: PA pressure 90/58/40 mmHg, normal PCWP, high PVR, mild cardiac index reduction. Due to critical clinical situation, Sildenafil 20 mg was started as an off–label therapy for PH (group 5). Subsequently, the patient experienced gradual but constant hemodynamic and clinical improvement and was discharged in NYHA class II. At 1 month control, patient was stable, echocardiogram revealed improvement in right ventricle dimension, systolic function and right atrial enlargement. At three months, patient is still in an intermediate risk class for PH, so we are evaluating a combination therapy (either endothelin receptor antagonist or prostanoids), taking into account anemia and thrombocytopenia. Take home message: PH can be a complication of hematological disorders as myelofibrosis, included in “mixed” forms (group 5) of PH. In our patient, after a challenging management for acute right heart failure, an off–label PDE–5 inhibitor stabilized the clinical scenario: more data are needed on PH drugs use in this setting where up to now therapeutic strategies are lacking.

After 30 years, the first endothelin-receptor antagonist (Aprocitentan) is approved for the treatment of arterial hypertension.

After 30 years, the first endothelin-receptor antagonist (Aprocitentan) is approved for the treatment of arterial hypertension.

Women's health and kidney protective medications.

We discuss the sex-based differences in the pharmacokinetics and pharmacodynamics of kidney protective medications and their implications on women's health. A critical examination of adverse drug reactions highlights the underrepresentation of women in clinical trials for kidney and cardiovascular protective drugs, such as SGLT2 inhibitors, ACE inhibitors, and endothelin receptor antagonists. This underscores the need for sex-specific analyses in clinical studies to accurately assess medication efficacy and safety. The research demonstrates that women are more likely to experience adverse events and less likely to benefit from certain treatments, emphasizing the urgent need for healthcare providers to adopt a sex-informed approach in prescribing practices. Future research should prioritize sex differences from the outset to enhance understanding and improve clinical outcomes for women with chronic kidney disease and cardiovascular conditions.

Endothelin-1 Receptor Antagonism Attenuates Increased Uncoupling Protein-1 in Brown Adipose Tissue of Obese Mice

Endothelin-1 (ET-1) is increased in patients and rodent models with obesity and promotes metabolic syndrome by causing inflammation and adipocyte dysfunction. Recently, our laboratory demonstrated that treatment of obese mice with Atrasentan (Atr) and Bosentan (Bos) significantly improved fasting blood glucose, insulin, and glucose and insulin tolerance; however, the mechanisms are not completely understood. Brown adipocytes express all components of the ET-1 system and are important in limiting adiposity though an increase in uncoupling protein-1 (UCP-1) leading to increased metabolism via thermogenesis. We hypothesized that ET-1 antagonism may improve metabolism in obese mice by regulating UCP-1 in brown adipose. Mice were fed either normal (NMD) or high fat diet (HFD) for 10 week and treated with either vehicle, Atr, or Bos for the final two weeks. HFD significantly increased ET-1 and tumor necrosis factor alpha expression in brown adipose tissue compared to NMD controls with no significant effect of either ET-1 receptor antagonists. Interestingly, brown adipose expression of UCP-1 was significantly increased in HFD fed mice compared to NMD, an effect that was significantly attenuated in mice treated with atrasentan and bosentan. These data suggest that ET-1 modulates brown adipose tissue function in obesity, a potential contributor to obesity induced cardio metabolic risk. This work was supported by National Institutes of Health grant 5T32HL105324-14. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effectiveness of a Prostacyclin IP Receptor Agonist in Patients With Pulmonary Arterial Hypertension in the Real-world Andalusian Setting: The RAMPHA Study

PurposeThe pillar for therapeutic decisions in the evolution of pulmonary arterial hypertension (PAH) is the patients’ prognostic stratification. MethodsA retrospective cohort study was conducted in a Spanish real-world setting to assess the clinical improvement of PAH patients treated with selexipag measured as changes in the risk profile. Secondary objectives were to describe their baseline characteristics, initial risk status, and variables used to assess patient survival and adverse events. FindingsTotal 42 patients (mean age 52.36 [SD: 15.09] years) were included. All had received initial endothelin receptor antagonist treatment and 95.2% dual therapy with phosphodiesterase-5 inhibitor or riociguat. At 6 to 12 months from baseline, patients risk stratification tripled the percentage of patients with low risk, and a trend towards improved risk stratification (P = 0.122). World Health Organization functional class changed, with more patients in milder classes (P = 0.003), and symptom progression slowed down (P < 0.0001). At 3-years, survival was 85.7% and the estimated median survival time was 2.73 years (SD: 1.351; 95% CI: 2.51–2.95). ImplicationsSelexipag did not achieve a significant improvement in risk profile, although it did show an excellent survival rate, effectively improved functional class, and delayed symptom progression in real life. Selexipag was well tolerated and showed a favorable safety profile, supporting a clinical benefit for PAH patients.

Effect of Endothelin-1 on Resting Blood Pressure and the Blood Pressure Response to Hypoxia in Healthy Young Men

Objectives: Upregulation of endothelin-1 (ET-1) and its receptors have been linked to increases in hypoxic sensitivity of the carotid chemoreceptors and the development of hypertension. As such, chemoreflex sensitization has been shown in pre-clinical models to be attenuated by ET-1 receptor blockade. Herein, we sought to assess a role for ET-1 in the maintenance of resting blood pressure (BP) in healthy young men and determine whether chemoreflex control of BP could be altered by ET-1 blockade. We hypothesized endothelin receptor antagonism with oral bosentan would lower resting BP in healthy young men as well as the acute BP response to hypoxia. Methods: Twenty-four healthy young men (31±5 yrs, 26±3 kg/m2) completed two study visits (control, bosentan) separated by a minimum of 1 week. The nonspecific endothelin receptor antagonist bosentan (62.5 mg) was taken by mouth twice daily for 3 days prior to the second study visit. On each visit, beat-by-beat BP was assessed under 3 inspiratory air conditions: 1) steady-state normoxia (FiO2 0.21), 2) chemoreflex excitation produced by acute, graded hypoxia (FiO2 0.05 – 0.21), 3) chemoreflex inhibition elicited by transient hyperoxia (FiO2 1.00). Results: Oral bosentan treatment resulted in an increase in plasma ET-1 (0.9±0.9 to 1.3±0.6 pg/mL, p=0.004), supporting receptor blockade. Resting diastolic and mean BP were reduced following 3 days of bosentan treatment compared to control (diastolic: 73±5 to 69±7 mmHg, p=0.007; mean: 93±7 to 88±7 mmHg, p=0.005) with no change in systolic BP (p=0.507). Notably, the BP response to both acute hypoxia (-0.48±0.38 to -0.25±0.31 mmHg/%, p=0.004) and hyperoxia (main effect of bosentan, p=0.025) were attenuated following bosentan. Conclusions: Acute oral bosentan treatment resulted in a reduction in resting BP in healthy young men. The effect of endothelin receptor inhibition with bosentan further attenuated the rise in BP during chemoreflex excitation via acute, graded hypoxia as well as the fall in BP during chemoreflex inhibition (transient hyperoxia). Together these data support a role for ET-1 in control of resting BP in healthy young men, possibly through a chemoreceptor-mediated mechanism. NIH HL130339 (JL), Mayo Clinic Center for Biomedical Discovery (JL, SB). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Switching from Beraprost to Selexipag in the Treatment of Pulmonary Arterial Hypertension: Insights from a Phase IV Study of the Japanese Registry (The EXCEL Study: EXChange from bEraprost to seLexipag Study).

Pulmonary arterial hypertension (PAH) remains a significant challenge in cardiology, necessitating advancements in treatment strategies. This study explores the safety and efficacy of transitioning patients from beraprost to selexipag, a novel selective prostacyclin receptor agonist, within a Japanese cohort. Employing a multicenter, open-label, prospective design, 25 PAH patients inadequately managed on beraprost were switched to selexipag. Key inclusion criteria included ongoing beraprost therapy for ≥3 months, a diagnosis of PAH confirmed by mean pulmonary artery pressure (mPAP) ≥ 25 mmHg, and current treatment with endothelin receptor antagonists and/or phosphodiesterase type 5 inhibitors. Outcomes assessed were changes in hemodynamic parameters (mPAP, cardiac index, pulmonary vascular resistance) and the 6 min walk distance (6-MWD) over 3-6 months. The study found no statistically significant changes in these parameters post-switch. However, a subset of patients, defined as responders, demonstrated improvements in all measured hemodynamic parameters, suggesting a potential benefit in carefully selected patients. The transition was generally well-tolerated with no serious adverse events reported. This investigation underscores the importance of personalized treatment strategies in PAH, highlighting that certain patients may benefit from switching to selexipag, particularly those previously on higher doses of beraprost. Further research is needed to elucidate the predictors of positive response to selexipag and optimize treatment regimens for this complex condition.

Unmet need in PH-ILD: A clinician survey of real-world management of PH-ILD in Europe

BackgroundWith no approved therapies for pulmonary hypertension (PH) associated with interstitial lung disease (PH-ILD) in Europe, we surveyed clinician perceptions on PH-ILD management and unmet need to understand current real-world practices.Methods: An online clinician survey on PH-ILD management was conducted in France, Germany, Italy, Spain, and the UK.Results: Fifty-five clinicians (78% pulmonologists) each managing a median 20 PH-ILD patients (interquartile range [IQR]=10–50), participated. Upon PH suspicion, clinicians referred a median 50% (IQR=20–73%) of patients for echocardiography alone and 35% (IQR=20–78%) for echocardiography, followed by right heart catheterisation.Upon diagnosis, a median 20% (IQR=9–30%), 40% (IQR=20–50%) and 35% (IQR=20–55%) of patients fell under the pulmonary arterial pressure ranges of 21–24mmHg, 25–34mmHg and &gt;35mmHg respectively. Fifty percent of patients received off-label treatment for their PH and, of those, off-label phosphodiesterase-5 inhibitor (PDE-5i), endothelin receptor antagonist (ERA) and prostacyclin analogues were prescribed first-line by 78%, 9% and 7% of clinicians, respectively. Upon PDE-5i non-response, 35% of clinicians proceed with an ERA, 35% with no further therapy. Fifty-five percent of clinicians used dual therapy. Yearly median inpatient admissions and emergency visits were 2.0 (IQR=1.3–2.9) and 1.5 (IQR=1.0–2.0) respectively (n=31 responses). Most clinicians (69%) highlighted lack of efficacy or evidence for current therapies as a key gap in PH-ILD management.ConclusionsThis study gives insight into real-world European PH-ILD diagnosis and management. With significant use of off-label treatment, there is a large unmet need due to lack of approved therapies. Despite updated guidelines, more evidence is needed to standardise PH-ILD management.

IL-6/gp130 signaling in CD4+ T cells drives the pathogenesis of pulmonary hypertension

Pulmonary arterial hypertension (PAH) is characterized by stenosis and occlusions of small pulmonary arteries, leading to elevated pulmonary arterial pressure and right heart failure. Although accumulating evidence shows the importance of interleukin (IL)-6 in the pathogenesis of PAH, the target cells of IL-6 are poorly understood. Using mice harboring the floxed allele of gp130, a subunit of the IL-6 receptor, we found substantial Cre recombination in all hematopoietic cell lineages from the primitive hematopoietic stem cell level in SM22α-Cre mice. We also revealed that a CD4+ cell-specific gp130 deletion ameliorated the phenotype of hypoxia-induced pulmonary hypertension in mice. Disruption of IL-6 signaling via deletion of gp130 in CD4+ T cells inhibited phosphorylation of signal transducer and activator of transcription 3 (STAT3) and suppressed the hypoxia-induced increase in T helper 17 cells. To further examine the role of IL-6/gp130 signaling in more severe PH models, we developed Il6 knockout (KO) rats using the CRISPR/Cas9 system and showed that IL-6 deficiency could improve the pathophysiology in hypoxia-, monocrotaline-, and Sugen5416/hypoxia (SuHx)-induced rat PH models. Phosphorylation of STAT3 in CD4+ cells was also observed around the vascular lesions in the lungs of the SuHx rat model, but not in Il6 KO rats. Blockade of IL-6 signaling had an additive effect on conventional PAH therapeutics, such as endothelin receptor antagonist (macitentan) and soluble guanylyl cyclase stimulator (BAY41-2272). These findings suggest that IL-6/gp130 signaling in CD4+ cells plays a critical role in the pathogenesis of PAH.

Maximizing the Therapeutic Effect of Endothelin Receptor Antagonists in Pulmonary Fibrosis: A Paradigm for Treating the Disease.

Using a lipopolysaccharide model of acute lung injury, we previously showed that endothelin-1 (ET-1), a potent mediator of vasoconstriction, may act as a "gatekeeper" for the influx of inflammatory cells into the lung. These studies provided a rationale for testing the effect of HJP272, an endothelin receptor antagonist (ERA), in hamster models of pulmonary fibrosis induced by intratracheal instillation of either bleomycin (BLM) or amiodarone (AM). To determine the temporal effects of blocking ET-1 activity, animals were given HJP272 either 1 h before initiation of lung injury or 24 h afterward. The results indicated that pretreatment with this agent caused significant reductions in various inflammatory parameters, whereas post-treatment was ineffective. This finding suggests that ERAs are only effective at a very early stage of pulmonary fibrosis and explains their lack of success in clinical trials involving patients with this disease. Nevertheless, ERAs could serve as prophylactic agents when combined with drugs that may induce pulmonary fibrosis. Furthermore, developing a biomarker for the initial changes in the lung extracellular matrix could increase the efficacy of ERAs and other therapeutic agents in preventing the progression of the disease. While no such biomarker currently exists, we propose the ratio of free to peptide-bound desmosine, a unique crosslink of elastin, as a potential candidate for detecting the earliest modifications in lung microarchitecture associated with pulmonary fibrosis.

The biased apelin receptor agonist, MM07, reverses Sugen/hypoxia-induced pulmonary arterial hypertension as effectively as the endothelin antagonist macitentan.

Introduction: Pulmonary arterial hypertension (PAH) is characterised by endothelial dysfunction and pathological vascular remodelling, resulting in the occlusion of pulmonary arteries and arterioles, right ventricular hypertrophy, and eventually fatal heart failure. Targeting the apelin receptor with the novel, G protein-biased peptide agonist, MM07, is hypothesised to reverse the developed symptoms of elevated right ventricular systolic pressure and right ventricular hypertrophy. Here, the effects of MM07 were compared with the clinical standard-of-care endothelin receptor antagonist macitentan. Methods: Male Sprague-Dawley rats were randomised and treated with either normoxia/saline, or Sugen/hypoxia (SuHx) to induce an established model of PAH, before subsequent treatment with either saline, macitentan (30mg/kg), or MM07 (10mg/kg). Rats were then anaesthetised and catheterised for haemodynamic measurements, and tissues collected for histopathological assessment. Results: The SuHx/saline group presented with significant increases in right ventricular hypertrophy, right ventricular systolic pressure, and muscularization of pulmonary arteries compared to normoxic/saline controls. Critically, MM07 was as at least as effective as macitentan in significantly reversing detrimental structural and haemodynamic changes after 4weeks of treatment. Discussion: These results support the development of G protein-biased apelin receptor agonists with improved pharmacokinetic profiles for use in human disease.

Molecular Targets of Novel Therapeutics for Diabetic Kidney Disease: A New Era of Nephroprotection.

Diabetic kidney disease (DKD) is a chronic microvascular complication in patients with diabetes mellitus (DM) and the leading cause of end-stage kidney disease (ESKD). Although glomerulosclerosis, tubular injury and interstitial fibrosis are typical damages of DKD, the interplay of different processes (metabolic factors, oxidative stress, inflammatory pathway, fibrotic signaling, and hemodynamic mechanisms) appears to drive the onset and progression of DKD. A growing understanding of the pathogenetic mechanisms, and the development of new therapeutics, is opening the way for a new era of nephroprotection based on precision-medicine approaches. This review summarizes the therapeutic options linked to specific molecular mechanisms of DKD, including renin-angiotensin-aldosterone system blockers, SGLT2 inhibitors, mineralocorticoid receptor antagonists, glucagon-like peptide-1 receptor agonists, endothelin receptor antagonists, and aldosterone synthase inhibitors. In a new era of nephroprotection, these drugs, as pillars of personalized medicine, can improve renal outcomes and enhance the quality of life for individuals with DKD.