Endothelin Receptor Antagonists in Kidney Disease

Endothelin (ET) is found to be increased in kidney disease secondary to hyperglycaemia, hypertension, acidosis, and the presence of insulin or proinflammatory cytokines. In this context, ET, via the endothelin receptor type A (ET_A) activation, causes sustained vasoconstriction of the afferent arterioles that produces deleterious effects such as hyperfiltration, podocyte damage, proteinuria and, eventually, GFR decline. Therefore, endothelin receptor antagonists (ERAs) have been proposed as a therapeutic strategy to reduce proteinuria and slow the progression of kidney disease. Preclinical and clinical evidence has revealed that the administration of ERAs reduces kidney fibrosis, inflammation and proteinuria. Currently, the efficacy of many ERAs to treat kidney disease is being tested in randomized controlled trials; however, some of these, such as avosentan and atrasentan, were not commercialized due to the adverse events related to their use. Therefore, to take advantage of the protective properties of the ERAs, the use of ET_A receptor-specific antagonists and/or combining them with sodium-glucose cotransporter 2 inhibitors (SGLT2i) has been proposed to prevent oedemas, the main ERAs-related deleterious effect. The use of a dual angiotensin-II type 1/endothelin receptor blocker (sparsentan) is also being evaluated to treat kidney disease. Here, we reviewed the main ERAs developed and the preclinical and clinical evidence of their kidney-protective effects. Additionally, we provided an overview of new strategies that have been proposed to integrate ERAs in kidney disease treatment.

Endothelin-1 is increased in the plasma of patients hospitalised with Covid-19

Virus induced endothelial dysregulation is a well-recognised feature of severe Covid-19 infection. Endothelin-1 (ET-1) is the most highly expressed peptide in endothelial cells and a potent vasoconstrictor, thus representing a potential therapeutic target. ET-1 plasma levels were measured in a cohort of 194 Covid-19 patients stratified according to the clinical severity of their illness. Hospitalised patients, including those who died and those developing acute myocardial or kidney injury, had significantly elevated ET-1 plasma levels during the acute phase of infection. The results support the hypothesis that endothelin receptor antagonists may provide clinical benefit for certain Covid-19 patients.

Prostacyclins and pulmonary arterial hypertension in children

OBJECTIVE

Despite its low incidence, pulmonary hypertension in children places a substantial burden on families and society because survival can be shorter than 10 months and treatment options are limited and ineffective. Drugs to treat pulmonary hypertension include endothelin antagonists, phosphodiesterase type 5 inhibitors and prostacyclin, which is the most widely used to treat pediatric pulmonary hypertension. The main aim of this study was to provide a comprehensive overview of the advantages and disadvantages of prostacyclin and its analogs for treating pulmonary hypertension in children.

MATERIALS AND METHODS

To retrieve a thorough collection of studies, we performed a search in PubMed using the following combination of keywords: (Prostacyclins) or (Epoprostenol) or (Iloprost) or (Treprostinil) or (Beraprost), (children) and (pulmonary arterial hypertension). The time limits used for the search were December 1983 to May 2021.

RESULTS

The search retrieved a total of 238 articles. Titles and abstracts of articles were screened for relevance, and all relevant articles published in English were included.

CONCLUSIONS

Epoprostenol can be effective against severe pulmonary hypertension. Iloprost can treat severe persistent pulmonary hypertension in newborns and inhaled iloprost can be used in pulmonary vasoreactivity testing. Treprostinil is a long-acting prostacyclin analog, and it shows the highest antiproliferative activity among prostacyclins. Beraprost may be effective in premature infants, but available evidence comes from only one patient, so more clinical testing is needed.

Ameliorative role of bosentan, an endothelin receptor antagonist, against sodium arsenite-induced renal dysfunction in rats

Arsenic exposure is well documented to cause serious health hazards, such as cardiovascular abnormalities, neurotoxicity and nephrotoxicity. In the present study, we intended to explore the role of bosentan, an endothelial receptor antagonist, against sodium arsenite-induced nephrotoxicity and hepatotoxicity in rats. Sodium arsenite (5 mg/kg, oral) was administered for 4 weeks to induce renal dysfunction in rats. Sodium arsenite intoxicated rats were treated with bosentan (50 and 100 mg/kg, oral) for 4 weeks. Arsenic led renal damage was demonstrated by significant increase in serum creatinine, urea, uric acid, potassium, fractional excretion of sodium, microproteinuria and decreased creatinine clearance in rats. Sodium arsenite resulted in marked oxidative stress in rat kidneys as indicated by profound increase in lipid peroxides, and superoxide anion generation alongwith decrease in reduced glutathione levels. Hydroxyproline assay highlighted arsenic-induced renal fibrosis in rats. Hematoxylin-eosin staining indicated glomerular and tubular changes in rat kidneys. Picrosirius red staining highlighted collagen deposition in renal tissues of arsenic treated rats. Immunohistological results demonstrated the reduction of renal eNOS expression in arsenic treated rats. Notably, treatment with bosentan attenuated arsenic-induced renal damage and resisted arsenic-led reduction in renal eNOS expression. In addition, sodium arsenite-induced alteration in hepatic parameters (serum aspartate aminotransferase, alanine transferase, alkaline phosphatase, bilirubin), oxidative stress and histological changes were abrogated by bosentan treatment in rats. Hence, we conclude that bosentan treatment attenuated sodium arsenite-induced oxidative stress, fibrosis and reduction in renal eNOS expression in rat kidneys. Moreover, bosentan abrogated arsenic led hepatic changes in rats.

Collaborative registry of pulmonary hypertension in Argentina (RECOPILAR). Final analysis

The epidemiology of pulmonary hypertension (PH), especially pulmonary arterial hypertension (PAH), has not been evaluated in our country, therefore there is no reference parameter to establishing the representativeness of this information in the national order. This registry represents the first collaborative effort to provide a knowledge base of this disease, including 5 scientific societies that represent different specialties (pediatrics, rheumatology, pulmonology and cardiology) with data from 23 Argentine provinces. These efforts involved five societies of various adult (cardiology, rheumatology, and pulmonology) and pediatric (cardiology) specialties. Subjects were grouped (1-5) in accord with the 2013 Nice classification. A total of 627 patients (mean age, 50.8 ± 18 years; women, 69.2%) were recruited. Incident cases accounted for 53%. Functional class III-IV accounted for 69% at time of diagnosis and 33.4% at time of inclusion. Distributions in groups 1-5 were 63.6%, 15.9%, 8.3%, 9.7%, and 2.4%, respectively. Treatment consisted of diuretics (51.2%), mineralocorticoid receptor antagonists (44.7%), digoxin (16.6%), anticoagulants (39.2%), renin-angiotensin antagonists (15.5%), beta blockers (15.6%), and calcium channel blockers (8%). Rates of specific therapies usage in PAH vs. non-PAH group were 80.5% vs. 40.8% (phosphodiesterase-5 inhibitors: 71% vs. 38.6%; endothelin receptor antagonists: 54.4% vs. 14.5%; prostanoids: 14.3 vs. 3.1%; all p < 0.001). Three-year survival in PAH and non-PAH differed significantly (82.8% vs. 73.3%; p = 0.001). In the Argentine RECOPILAR registry, the clinic-epidemiologic profile was that of advanced-stage disease. Diagnostic workups and therapeutics interventions, including use of specific therapy for PAH, were consistent with current recommendations. Despite delays in diagnosis, survival was aligned with other contemporary registries.

[Pulmonary arterial hypertension (PAH ) : a new era of pulmonary arterial vasodilatators]

Pulmonary arterial hypertension (PAH) is a rare disease, characterized by a progressive increase in pulmonary arterial pressure. The therapeutic management of PAH patients has evolved significantly over the past decades following the appearance of new specific therapies, but also the performance of multiple clinical studies in an otherwise rare pathology. As a result, the care is very well codified and makes it possible to treat all patients at best. To date, we can cite four therapeutic families: endothelin receptor antagonists (ERA), drugs that interfere with the cyclic guanosine monophosphate (cGMP) pathway such as phosphodiesterase type 5 inhibitors (PDE5i) or the stimulator of soluble guanylate cyclase, prostacyclin analogues, and, finally, calcium antagonists. The therapeutic approach, formerly sequential, has proven to be insufficient in favor of an aggressive and rapidly progressive upfront therapeutic approach, making it possible to greatly improve the morbidity and mortality of patients. In this context, early management remains the most appropriate attitude and justifies recourse, from the first symptoms, to a competence center.

Involvement of Endothelin Receptors in Peripheral Sensory Neuropathy Induced by Oxaliplatin in Mice

The aim of this study was to evaluate the participation of the endothelin ET_A and ET_B receptors and the effects of bosentan in oxaliplatin-induced peripheral sensory neuropathy (OIN) in mice. Adult male Swiss mice received 1 mg/kg of oxaliplatin intravenously, twice a week for 5 weeks. Dorsal root ganglia (DRG) and spinal cords were removed for evaluation of the endothelin ET_A and ET_B receptor expression. Afterwards, selective (BQ-123 and BQ-788; 10 nmol in 30 μL, intraplantarly) and non-selective (bosentan, 100 mg/kg, orally) antagonists were administered in order to evaluate the involvement of the endothelin receptors in OIN. Mechanical and thermal nociception tests were performed once a week for 56 days. Oxaliplatin induced mechanical and thermal hypersensitivity and increased the endothelin ET_A receptor expression in both the DRG and spinal cord (P < 0.05). Endothelin ET_B receptor expression was increased in the DRG (P < 0.05) but not in the spinal cord. Both endothelin ET_A and ET_B receptor selective antagonists partially prevented mechanical hyperalgesia in mice with OIN (P < 0.05). Moreover, bosentan prevented mechanical and thermal hypersensitivity in oxaliplatin-treated mice (P < 0.05). In conclusion, both endothelin ET_A and ET_B receptors seem to be involved in the OIN in mice and they should be considered possible targets for the management of this clinical feature.

Sitaxsentan for Treatment of Pulmonary Hypertension

Objective:

To review the literature pertinent to the efficacy and safety of sitaxsentan, a selective endothelin (ET)-A receptor antagonist under evaluation for the treatment of pulmonary arterial hypertension (PAH).

Data Sources:

Articles were identified through searches of the MEDLINE (1966–November 2006) and International Pharmaceutical Abstracts (1970–November 2006) databases, using the key words endothelin antagonist, pulmonary arterial hypertension, pulmonary hypertension, sitaxsentan, and TBC11251. Searches were limited to articles published in English.

Study Selection And Data Extraction:

Due to the limited number of articles on sitaxsentan, all studies captured in the search results were evaluated.

Data Synthesis:

Four studies of sitaxsentan in humans with PAH have been published to date. An uncontrolled open-label study and a randomized placebo-controlled study (STRIDE-1; Sitaxsentan to Relieve Impaired Exercise-1) showed sitaxsentan to improve exercise tolerance in patients with PAH, as evidenced by significant increases in the distance walked in 6 minutes. Significant hepatotoxicity developed in patients receiving sitaxsentan 300 mg. The benefits of sitaxsentan with respect to exercise tolerance and hemodynamics were sustained in a one year extension of the placebo-controlled study. The results of a multicenter, randomized, placebo-controlled trial of 2 doses of sitaxsentan with an open-label bosentan arm (STRIDE-2) suggested that only the 100 mg dose provided superior benefit in exercise tolerance and improvement in functional class. Treatment-related adverse effects were similar for all groups.

Conclusions:

Sitaxsentan appears to be superior to placebo in improving exercise tolerance in patients with PAH but may produce therapeutic outcomes similar to those of bosentan, a comparator agent. The optimal dose of sitaxsentan appears to be 100 mg once daily. Information about the use of sitaxsentan in a greater number of patients with PAH for longer periods is necessary to further define its place in the treatment of PAH.

Diurnal variation in blood pressure and arterial stiffness in chronic kidney disease: the role of endothelin-1

Hypertension and arterial stiffness are important independent cardiovascular risk factors in chronic kidney disease (CKD) to which endothelin-1 (ET-1) contributes. Loss of nocturnal blood pressure (BP) dipping is associated with CKD progression, but there are no data on 24-hour arterial stiffness variation. We examined the 24-hour variation of BP, arterial stiffness, and the ET system in healthy volunteers and patients with CKD and the effects on these of ET receptor type A receptor antagonism (sitaxentan). There were nocturnal dips in systolic BP and diastolic BP and pulse wave velocity, our measure of arterial stiffness, in 15 controls (systolic BP, −3.2±4.8%, P<0.05; diastolic BP, −6.4±6.2%, P=0.001; pulse wave velocity, −5.8±5.2%, P<0.01) but not in 15 patients with CKD. In CKD, plasma ET-1 increased by 1.2±1.4 pg/mL from midday to midnight compared with healthy volunteers (P<0.05). Urinary ET-1 did not change. In a randomized, double-blind, 3-way crossover study in 27 patients with CKD, 6-week treatment with placebo and nifedipine did not affect nocturnal dips in systolic BP or diastolic BP between baseline and week 6, whereas dipping was increased after 6-week sitaxentan treatment (baseline versus week 6, systolic BP: −7.0±6.2 versus −11.0±7.8 mm Hg, P<0.05; diastolic BP: −6.0±3.6 versus −8.3±5.1 mm Hg, P<0.05). There was no nocturnal dip in pulse pressure at baseline in the 3 phases of the study, whereas sitaxentan was linked to the development of a nocturnal dip in pulse pressure. In CKD, activation of the ET system seems to contribute not only to raised BP but also the loss of BP dipping. The clinical significance of these findings should be explored in future clinical trials.

Endothelin receptor antagonists

Three pathways have been identified in the pathogenesis of pulmonary arterial hypertension (PAH): the endothelin (ET), nitric oxide (NO) and prostacyclin pathways. These pathways represent the targets of approved PAH therapies and their discovery has facilitated significant progress in the understanding and treatment of PAH. The ET system is well established as a key player in the pathophysiology of PAH, with deleterious effects mediated by both the ETA and ETB receptors. Endothelin receptor antagonists (ERAs) are an important part of PAH therapy, with two ERAs currently approved for the treatment of PAH and a novel ERA that has recently been investigated in a Phase III clinical trial. This chapter describes the role of ET in the pathogenesis of PAH, reviews experimental data and examines the clinical status of ERAs in PAH treatment.

Evaluation of the endothelin receptor antagonists ambrisentan, bosentan, macitentan, and sitaxsentan as hepatobiliary transporter inhibitors and substrates in sandwich-cultured human hepatocytes

Background

Inhibition of the transporter-mediated hepatobiliary elimination of bile salts is a putative mechanism for liver toxicity observed with some endothelin receptor antagonists (ERAs).

Methods

Sandwich-cultured human hepatocytes were used to study the hepatobiliary distribution and accumulation of exogenous taurocholate, ERAs and endogenous bile acids. The molecular mechanisms for findings in hepatocytes or clinical observations were further explored using either vesicular assays (efflux transporters) or transfected cell-lines (uptake transporters). Inhibition constants (IC₅₀) were measured for the human hepatobiliary transporters bile salt export pump (BSEP), sodium taurocholate cotransporting polypeptide (NTCP), multidrug resistance protein 2 (MRP2), P-glycoprotein (Pgp), breast cancer resistance protein (BCRP), organic anion-transporting polypeptide 1B1 (OATP1B1) and OATP1B3.

Results

The ERAs showed dose-dependent reductions in exogenous taurocholate cellular accumulation in human hepatocytes, with macitentan having the greatest effect. Consistent with their effects on bile acids, the ERAs inhibited bile transporters. IC₅₀ values for OATP1B1 and OATP1B3 ranged from 2 µM for macitentan to 47 µM for ambrisentan. Macitentan and bosentan also inhibited NTCP with IC₅₀ values of 10 and 36 µM, respectively. Similar to previously reported findings with sitaxsentan, BSEP inhibition was observed for bosentan and macitentan with IC₅₀ values of 42 and 12 µM, respectively. In contrast, ambrisentan showed little or no inhibition of these transporters. Other transporters tested were weakly inhibited by the ERAs. Accumulation in hepatocytes was also a factor in the effects on bile transport. Macitentan demonstrated the greatest accumulation in human hepatocytes (∼100x) followed by sitaxsentan (∼40x), bosentan (∼20x) and ambrisentan (∼2x).

Conclusions

Significant differences in the inhibition of hepatic transporters were observed between the evaluated ERAs in vitro. Macitentan had the highest level of cellular accumulation and caused the greatest effects on bile acid distribution in human hepatocytes followed by sitaxsentan and bosentan. Ambrisentan showed a low potential to affect bile acids.

Bosentan

Bosentan (Tracleer, Actelion Pharmaceuticals Ltd) is an oral dual endothelin receptor antagonist approved for use in functional class III to IV pulmonary arterial hypertension. In two placebo-controlled trials, patients receiving bosentan showed improved functional class, 6-minute walk distance and hemodynamics over a 12- to 16-week period. Follow-up data over 3 years has shown few deteriorations,with the majority of patients maintaining their response to bosentan alone. Investigations exploring the use of bosentan as an add-on agent to intravenous epoprostenol (Flolan, GlaxoSmithKline Plc) in those with the most severe disease are ongoing. Bosentan may also have antifibrotic properties and its use in pulmonary fibrosis is being explored. Ease of administration of bosentan with twice-daily oral dosing will provide many patients with pulmonary hypertension an option for treatment without the risks and discomforts of continuous intravenous medication.

[Choice of novel endpoints in clinical trials evaluating the efficiency of drug therapy in patients with pulmonary hypertension]

Pulmonary hypertension (PH) is characterized by a poor prognosis: the three-year survival rate in patients with PH is not greater than 60% as evidenced by current national registries. In the past decade, there have been drugs that are able to relieve symptoms of the disease, to slow down its progression, and improve quality of life. Historically, clinical trials dealing with PH have had a fixed and rather short-tern period and most commonly used the index "the change in the distance covered in the 6-minute walk test" as a primary endpoint. Further optimization of PH therapy requires that the efficacy of drugs and the strategies of therapy be evaluated with respect to their effects on morbidity and mortality, i.e. on prognosis. The SERAPHIN trial is now the only completed and published clinical trial using the combined index of morbidity and mortality as a primary endpoint. It demonstrates that that therapy with the novel drug macitentan causes a reduction in morbidity and mortality in patients with PH.

[Bosentan: a considerable increase in the survival of patients with pulmonary hypertension associated with systemic rheumatic diseases]

AIM

To evaluate the short-term efficacy of the nonselective endothelin receptor antagonist bosentan in the treatment of pulmonary hypertension (PH) associated with diffuse connective tissue diseases (CTD), as well as its effect on survival in both monotherapy and in combination with other PH-specific agents.

SUBJECTS AND METHODS

The study included 20 CDT-associated PH patients who had been hospitalized in 2009-2013. All the patients had valid diagnoses of scleroderma systematica (SDS) (n = 18) or systemic lupus erythematosus (SLE) (n = 2). Bosentan was given in an initial dose of 62.5 mg/day twice for 4 weeks, then 125 mg/day twice.

RESULTS

Eighteen patents completed therapy at 16 weeks. One patient with Functional Class (FC) IV PH associated with SDS died after 10 weeks of treatment because of PH progression; bosentan was discontinued in another patient following 4 weeks because of the enhanced activity of transaminases. The patients who had completed the investigation showed a significant FC decrease (from 2.9 +/- 1.0 to 2.4 +/- 1.0 following 16 weeks; p = 0.03), an increase in 6-minute walking distance (from 298 +/- 140 to 375 +/- 94 m; p < 0.002), a significant reduction in mean pulmonary artery pressure (from 48.2 +/- 15.0 to 42.8 +/- 12.0 mm Hg; p = 0.002), and pulmonary vascular resistance (PVR) (from 819 +/- 539 to 529 +/- 220 din/sec/cm(-5); p = 0.003). Right atrial pressure fell from 9.8 +/- 7.0 to 8.8 +/- 7.0 mm Hg; however, the changes were insignificant. There was a significant rise in cardiac index from 2.64 +/- 0.95 to 3.26 +/- 0.75 l/min/m2 (p = 0.005) and a significant decrease in uric acid levels from 562 +/- 254 to 469 +/- 194 micromol/l (p = 0.006). Overall 1-, 3-, and 5-year survival rates in patients with PH in the presence of CTD from PH onset were 100, 93, and 72%, respectively, in their treatment with endothelin receptor antagonists and differed significantly from the historical control group (87, 30, and 4%, respectively) when PH-specific therapy was unavailable.

CONCLUSION

The survival of the bosentan-treated patients with SDS and PH becomes similar to that in the patients with classical SDS. Analysis of the findings revealed the association of survival with lower PVR at 16 weeks of bosentan therapy, which is indicative of the need for hemodynamic monitoring of therapeutic effectiveness.

[Pulmonary arterial hypertension, a rare entity]

Pulmonary arterial hypertension (PAH) is a rare disease. It is characterized by the progressive remodeling of the small pulmonary arteries that lead to an elevation of the pulmonary vascular resistance and right ventricular dysfunction. Early diagnosis and prompt treatment avoid the deterioration of the patient's quality of life. Statistics show that there are 15 cases per million people worldwide, the majority comprised of young women, with an age at diagnosis of 30 to 40 years. At present, the exact processes that initiate the pathophysiologic changes observed in PAH are unknown; it is thought to be multifactorial. Diagnosis in PAH must be done in a step by step manner. Under the suspicion of pulmonary hypertension (PH), the first thing to do is confirm the diagnosis. The second step is to identify the specific etiology and lastly evaluate the severity by echocardiography, hemodynamic parameters, biomarkers and exercise capacity. PH treatment, particularly PAH, has evolved over the last 2 decades due to the advance in disease knowledge and the availability of agents that act on different pathways. Concerning surgical treatment, it is indicated in PAH when there is not an adequate response to medical treatment. In conclusion, PAH is recognized worldwide as a rare or infrequent disease. The countries that have a registry for the diagnostics, treatment, follow-up and prevalence of PH are mainly in Europe. With the exception of the United States and Canada, there are no registries in America. Recent years have shown an important advance in Latin America.

Effect of endothelin inhibition on lung fibroblasts on patients with systemic sclerosis

AIM

The aim of the study was to investigate the effect of selective ETRA Sitaxsentan on viability and differentiation into myofibroblasts of lung fibroblasts derived from SSc-ILD patients and the ability of this drug to modify the lung fibroblast synthesis of VEGF, type I collagen and fibronectin.

METHODS

Primary human lung fibroblast cultures were obtained from BAL of SSc-ILD patients. Cell cultures were exposed for 48 h to crescent concentrations of Sitaxsentan (10 -6M to 10 -4M). In these experimental conditions we evaluated cell viability through crystal violet staining, the production and mRNA expression of VEGF, fibronectin and type I collagen respectively through ELISA and real-Time PCR. Further, we detected alpha-Smooth Muscle Actin (α-SMA) through immunocytochemical assay.

RESULTS

The lowest concentration of sitaxsentan (10-6M) did not affect fibroblasts viability; conversely at higher concentrations, sitaxsentan induced a significant inhibition of cell viability. Synthesis and mRNA expression of VEGF, type 1 collagen and fibronectin were significantly reduced in treated lung fibroblasts compared to the untreated ones, in a dose-dependent manner. At higher concentrations, Sitaxsentan reduced the expression of α-SMA.

CONCLUSION

The results of this study show that sitaxentan is able in vitro to reduce both cell viability than production of VEGF and extra-cellular matrix components in SSc lung fibroblasts, confirming the anti-fibrotic potential of ETRA in SSc. The decreased expression of α-SMA in treated cells indicate that sitaxsentan may inhibit the fibroblast differentiation toward a myo-fibroblast phenotype and further support the hypothesis that the selective ETRAs may be beneficial in patients with SSc-ILD as anti fibrotic agents.

Riociguat for the treatment of pulmonary arterial hypertension

BACKGROUND

Riociguat, a soluble guanylate cyclase stimulator, has been shown in a phase 2 trial to be beneficial in the treatment of pulmonary arterial hypertension.

METHODS

In this phase 3, double-blind study, we randomly assigned 443 patients with symptomatic pulmonary arterial hypertension to receive placebo, riociguat in individually adjusted doses of up to 2.5 mg three times daily (2.5 mg-maximum group), or riociguat in individually adjusted doses that were capped at 1.5 mg three times daily (1.5 mg-maximum group). The 1.5 mg-maximum group was included for exploratory purposes, and the data from that group were analyzed descriptively. Patients who were receiving no other treatment for pulmonary arterial hypertension and patients who were receiving endothelin-receptor antagonists or (nonintravenous) prostanoids were eligible. The primary end point was the change from baseline to the end of week 12 in the distance walked in 6 minutes. Secondary end points included the change in pulmonary vascular resistance, N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, World Health Organization (WHO) functional class, time to clinical worsening, score on the Borg dyspnea scale, quality-of-life variables, and safety.

RESULTS

By week 12, the 6-minute walk distance had increased by a mean of 30 m in the 2.5 mg-maximum group and had decreased by a mean of 6 m in the placebo group (least-squares mean difference, 36 m; 95% confidence interval, 20 to 52; P<0.001). Prespecified subgroup analyses showed that riociguat improved the 6-minute walk distance both in patients who were receiving no other treatment for the disease and in those who were receiving endothelin-receptor antagonists or prostanoids. There were significant improvements in pulmonary vascular resistance (P<0.001), NT-proBNP levels (P<0.001), WHO functional class (P=0.003), time to clinical worsening (P=0.005), and Borg dyspnea score (P=0.002). The most common serious adverse event in the placebo group and the 2.5 mg-maximum group was syncope (4% and 1%, respectively).

CONCLUSIONS

Riociguat significantly improved exercise capacity and secondary efficacy end points in patients with pulmonary arterial hypertension. (Funded by Bayer HealthCare; PATENT-1 and PATENT-2 ClinicalTrials.gov numbers, NCT00810693 and NCT00863681, respectively.).