Effect of off-label targeted drugs on long-term survival in chronic thromboembolic pulmonary hypertension: Insights from a national multicentre prospective registry.

BACKGROUND AND OBJECTIVE: Off-label pulmonary arterial hypertension (PAH)-targeted drugs are commonly prescribed for non-operated chronic thromboembolic pulmonary hypertension (CTEPH), but their effect on the long-term prognosis of CTEPH remains unknown. This study investigated the effect of off-label PAH-targeted drugs on the long-term survival of CTEPH patients. METHODS: CTEPH patients were enrolled from a prospective multicentre national registry. Except for licensed riociguat and treprostinil, other PAH-targeted drugs were off-label. In the original and propensity score-matched (PSM) samples, five-year survival was compared in two groups: (a) patients not receiving off-label PAH-targeted drugs (control) versus (b) patients receiving off-label PAH-targeted drugs (treatment). The latter group was investigated for the effect of started off-label PAH-targeted drugs at baselines (initial) or during follow-up (subsequent). RESULTS: Of 347 enrolled patients, 212 were treated with off-label PAH-targeted drugs initially (n = 173) or subsequently (n = 39), and 135 were untreated. The 1-, 2-, 3- and 5-year survival of the treatment group was significantly higher than that of the control group (97.1% vs. 89.4%, 92.3% vs. 82.1%, 83.2% vs. 75.1% and 71.1% vs. 55.3%, respectively, log-rank test, p = 0.005). Initial treatment was correlated with better 5-year survival after excluding patients with subsequent treatment to reduce the immortal-time bias (hazard ratio: 0.611; 95% CI: 0.397-0.940; p = 0.025). In PSM samples, patients given initial treatment showed significantly better 5-year survival than untreated patients (68.9% vs. 49.3%, log-rank test, p = 0.008). CONCLUSION: Off-label targeted drugs contributed to improved long-term survival in CTEPH patients receiving pharmacotherapies.

Bosentan in the treatment of persistent pulmonary hypertension in newborns: a systematic review and meta-analysis.

BACKGROUND: Persistent pulmonary hypertension of the newborn is a life-threatening condition that affects about 1-2 per 1,000 live births worldwide. Bosentan is an oral dual endothelin receptor antagonist that may have a beneficial effect on persistent pulmonary hypertension of the newborn by reducing pulmonary vascular resistance and improving oxygenation. However, its role in persistent pulmonary hypertension of the newborn remains unclear. OBJECTIVES: To systematically evaluate the efficacy and safety of bosentan as an adjuvant therapy for persistent pulmonary hypertension of the newborn in newborns. METHODS: We searched six English and two Chinese databases from their inception to 1 January 2023 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We included randomised controlled trials and retrospective studies that compared bosentan with placebo or other drugs for persistent pulmonary hypertension of the newborn in newborns. We performed a meta-analysis using random-effects models and assessed the risk of bias and heterogeneity in the included studies. RESULTS: We included 10 studies with a total of 550 participants. Bosentan significantly reduced the treatment failure rate (relative risk = 0.25, P < 0.001), pulmonary artery pressure (mean difference = -11.79, P < 0.001), and length of hospital stay (mean difference = -1.04, P = 0.003), and increased the partial pressure of oxygen (mean difference = 10.02, P < 0.001) and blood oxygen saturation (SpO2) (mean difference = 8.24, P < 0.001) compared with a placebo or other drugs. The occurrence of adverse reactions was not significantly different between bosentan and a placebo or other drugs. CONCLUSIONS: Bosentan is effective in the treatment of persistent pulmonary hypertension of the newborn but adverse reactions such as abnormal liver function should be observed when using it.

The Anti-Atherosclerotic Effects of Endothelin Receptor Antagonist, Bosentan, in Combination with Atorvastatin-An Experimental Study.

Bosentan, an endothelin receptor antagonist (ERA), has potential anti-atherosclerotic properties. We investigated the complementary effects of bosentan and atorvastatin on the progression and composition of the atherosclerotic lesions in diabetic mice. Forty-eight male ApoE-/- mice were fed high-fat diet (HFD) for 14 weeks. At week 8, diabetes was induced with streptozotocin, and mice were randomized into four groups: (1) control/COG: no intervention; (2) ΒOG: bosentan 100 mg/kg/day per os; (3) ATG: atorvastatin 20 mg/kg/day per os; and (4) BO + ATG: combined administration of bosentan and atorvastatin. The intra-plaque contents of collagen, elastin, monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-a (TNF-a), matrix metalloproteinases (MMP-2, -3, -9), and TIMP-1 were determined. The percentage of lumen stenosis was significantly lower across all treated groups: BOG: 19.5 ± 2.2%, ATG: 12.8 ± 4.8%, and BO + ATG: 9.1 ± 2.7% compared to controls (24.6 ± 4.8%, p < 0.001). The administration of both atorvastatin and bosentan resulted in significantly higher collagen content and thicker fibrous cap versus COG (p < 0.01). All intervention groups showed lower relative intra-plaque concentrations of MCP-1, MMP-3, and MMP-9 and a higher TIMP-1concentration compared to COG (p < 0.001). Importantly, latter parameters presented lower levels when bosentan was combined with atorvastatin compared to COG (p < 0.05). Bosentan treatment in diabetic, atherosclerotic ApoE-/- mice delayed the atherosclerosis progression and enhanced plaques' stability, showing modest but additive effects with atorvastatin, which are promising in atherosclerotic cardiovascular diseases.

Bosentan attenuates sickle cell disease erythrocyte HbS polymerization and impaired deformability induced by endothelin-1.

The effects of endothelin-1 (ET-1) on erythrocytes from sickle cell disease (SCD) patients have been described, but mechanisms of ET-1 regarding primary erythrocyte functions remain unknown. ET-1 is a vasoconstrictor peptide produced by endothelial cells, and the expression of ET-1 is increased in SCD. The present study used ex vivo experiments with sickle cell erythrocytes, ET-1, and bosentan, a dual antagonist of ETA and ETB receptors. We performed a hemoglobin S (HbS) polymerization assay with three concentrations of ET-1 (1, 20, and 50 pg/mL) and bosentan (100 nmol/L). ET-1 increased HbS polymerization at all concentrations, and this effect was suppressed by bosentan. For the deformability assay, red blood cells (RBCs) were incubated on a Sephacryl column with the same concentrations of ET-1 and bosentan. ET-1 decreased deformability, and this effect was reversed by bosentan. To observe erythrocyte adhesion, ET-1 and bosentan were incubated with RBCs in thrombospondin-coated 96-well plate, which demonstrated that ET-1 decreased adhesion but that bosentan enhanced adhesion. We also assessed erythrocyte apoptosis and observed decreased eryptosis induced by ET-1, and these effects were inhibited bosentan. Thus, these findings demonstrated that ET-1 modulates HbS polymerization, erythrocyte deformability, adhesion to thrombospondin, and eryptosis, and these effects were suppressed or enhanced by bosentan.

Endothelin-1 Induces Cell Proliferation and Myofibroblast Differentiation through the ETAR/Gαq/ERK Signaling Pathway in Human Cardiac Fibroblasts.

Endothelin-1 (ET-1) has been implicated in the pathogenesis of cardiac fibrosis. Stimulation of endothelin receptors (ETR) with ET-1 leads to fibroblast activation and myofibroblast differentiation, which is mainly characterized by an overexpression of α-smooth muscle actin (α-SMA) and collagens. Although ET-1 is a potent profibrotic mediator, the signal transductions and subtype specificity of ETR contributing to cell proliferation, as well as α-SMA and collagen I synthesis in human cardiac fibroblasts are not well clarified. This study aimed to evaluate the subtype specificity and signal transduction of ETR on fibroblast activation and myofibroblast differentiation. Treatment with ET-1 induced fibroblast proliferation, and synthesis of myofibroblast markers, α-SMA, and collagen I through the ETAR subtype. Inhibition of Gαq protein, not Gαi or Gßγ, inhibited these effects of ET-1, indicating the essential role of Gαq protein-mediated ETAR signaling. In addition, ERK1/2 was required for ETAR/Gαq axis-induced proliferative capacity and overexpression of these myofibroblast markers. Antagonism of ETR with ETR antagonists (ERAs), ambrisentan and bosentan, inhibited ET-1-induced cell proliferation and synthesis of α-SMA and collagen I. Furthermore, ambrisentan and bosentan promoted the reversal of myofibroblasts after day 3 of treatment, with loss of proliferative ability and a reduction in α-SMA synthesis, confirming the restorative effects of ERAs. This novel work reports on the ETAR/Gαq/ERK signaling pathway for ET-1 actions and blockade of ETR signaling with ERAs, representing a promising therapeutic strategy for prevention and restoration of ET-1-induced cardiac fibrosis.

Effectiveness of bosentan in the treatment of systemic sclerosis-related digital ulcers: Systematic review and meta-analysis.

Background: The aim of the present systematic review and meta-analysis was to evaluate the therapeutic efficacy of bosentan, a dual endothelin receptor antagonist, for systemic sclerosis (SSc) patients with digital ulcers (DUs). Materials and Methods: A systematic search of MEDLINE, Embase, Web of Science, and Scopus was done using appropriate keywords till September 2021. Weighted mean difference (WMD) as the effect of therapeutic efficacy of bosentan on continuous outcomes was an estimate. Furthermore, the pooled prevalence of diffuse SSc and limited SSc was computed. Fixed or random effects models when appropriate were used for data synthesis. Results: Totally, 469 patients, with a mean age ranging from 48.1 to 63.7 years, from 8 studies were included in the systematic review and meta-analysis. The pooled frequency of diffuse SSc and limited SSc was 56% (95% confidence interval [CI]: 39%, 73%) and 44% (95% CI: 27%, 61%). The pooled prevalence of new DUs following bosentan treatment was 21% (95% CI: 10%, 33%). The results of the meta-analysis showed a pooled mean decrease of WMD: -0.09 (95% CI: -0.020, 0.02, P = 0.10), WMD: -2.82 (95% CI: -5.91, 0.27, P = 0.07), and WMD: -6.65 (95% CI: -9.49, -3.82, P < 0.001) in mean SSc-Health Assessment Questionnaire, pain, and Rodnan score, respectively. Our meta-analysis also indicated a significant pooled decrease in the number of new DUs in SSc patients compared to placebo subjects (WMD: -0.89 [95% CI: -1.40, -0.37; P = 0.001]) and baseline values (WMD: -1.34 (95% CI: -1.95, -0.73; P < 0.001). Conclusion: Bosentan possibly is an efficacious treatment option for SSc-related DUs. Although further large-scale randomized clinical trials are required to confirm the preliminary finding and underlying mechanisms of action.

Dual endothelin receptor antagonism increases resting energy expenditure in people with increased adiposity.

Increased adiposity is associated with dysregulation of the endothelin system, both of which increase the risk of cardiovascular disease (CVD). Preclinical data indicate that endothelin dysregulation also reduces resting energy expenditure (REE). The objective was to test the hypothesis that endothelin receptor antagonism will increase REE in people with obesity compared with healthy weight individuals. Using a double blind, placebo-controlled, crossover design, 32 participants [healthy weight (HW): n = 16, BMI: 21.3 ± 2.8 kg/m2, age: 26 ± 7 yr and overweight/obese (OB): n = 16, BMI: 33.5 ± 9.5 kg/m2, age: 31 ± 6 yr] were randomized to receive either 125 mg of bosentan (ETA/B antagonism) or placebo twice per day for 3 days. Breath-by-breath gas exchange data were collected and REE was assessed by indirect calorimetry. Venous blood samples were analyzed for concentrations of endothelin-1 (ET-1). Treatment with bosentan increased plasma ET-1 in both OB and HW groups. Within the OB group, the changes in absolute REE (PLA: -77.6 ± 127.6 vs. BOS: 72.2 ± 146.6 kcal/day; P = 0.046). The change in REE was not different following either treatment in the HW group. Overall, absolute plasma concentrations of ET-1 following treatment with bosentan were significantly associated with kcal/day of fat (r = 0.488, P = 0.005), percentage of fat utilization (r = 0.415, P = 0.020), and inversely associated with the percentage of carbohydrates (r = -0.419, P = 0.019), and respiratory exchange ratio (r = -0.407, P = 0.023). Taken together, these results suggest that modulation of the endothelin system may represent a novel therapeutic approach to increase both resting metabolism and caloric expenditure, and reduce CVD risk in people with increased adiposity.NEW & NOTEWORTHY Findings from our current translational investigation demonstrate that dual endothelin A/B receptor antagonism increases total REE in overweight/obese individuals. These results suggest that modulation of the endothelin system may represent a novel therapeutic target to increase both resting metabolism and caloric expenditure, enhance weight loss, and reduce CVD risk in seemingly healthy individuals with elevated adiposity.

Endothelin-1 as a novel target for the prevention of metabolic dysfunction with intermittent hypoxia in male participants.

We examined the effect of intermittent hypoxia (IH, a hallmark feature of sleep apnea) on adipose tissue lipolysis and the role of endothelin-1 (ET-1) in this response. We hypothesized that IH can increase ET-1 secretion and plasma free fatty acid (FFA) concentrations. We further hypothesized that inhibition of ET-1 receptor activation with bosentan could prevent any IH-mediated increase in FFA. To test this hypothesis, 16 healthy male participants (32 ± 5 yr, 26 ± 2 kg/m2) were exposed to 30 min of IH in the absence (control) and presence of bosentan (62.5 mg oral twice daily for 3 days prior). Arterial blood samples for ET-1, epinephrine, and FFA concentrations, as well as abdominal subcutaneous adipose tissue biopsies (to assess transcription of cellular receptors/proteins involved in lipolysis), were collected. Additional proof-of-concept studies were conducted in vitro using primary differentiated human white preadipocytes (HWPs). We show that IH increased circulating ET-1, epinephrine, and FFA (P < 0.05). Bosentan treatment reduced plasma epinephrine concentrations and blunted IH-mediated increases in FFA (P < 0.01). In adipose tissue, bosentan had no effect on cellular receptors and proteins involved in lipolysis (P > 0.05). ET-1 treatment did not directly induce lipolysis in differentiated HWP. In conclusion, IH increases plasma ET-1 and FFA concentrations. Inhibition of ET-1 receptors with bosentan attenuates the FFA increase in response to IH. Based on a lack of a direct effect of ET-1 in HWP, we speculate the effect of bosentan on circulating FFA in vivo may be secondary to its ability to reduce sympathoadrenal tone.

Studies on the Vitrified and Cryomilled Bosentan.

In this paper, several experimental techniques [X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetry, Fourier transform infrared spectroscopy, and broad-band dielectric spectroscopy] have been applied to characterize the structural and thermal properties, H-bonding pattern, and molecular dynamics of amorphous bosentan (BOS) obtained by vitrification and cryomilling of the monohydrate crystalline form of this drug. Samples prepared by these two methods were found to be similar with regard to their internal structure, H-bonding scheme, and structural (α) dynamics in the supercooled liquid state. However, based on the analysis of α-relaxation times (dielectric measurements) predicted for temperatures below the glass-transition temperature (Tg), as well as DSC thermograms, it was concluded that the cryoground sample is more aged (and probably more physically stable) compared to the vitrified one. Interestingly, such differences in physical properties turned out to be reflected in the lower intrinsic dissolution rate of BOS obtained by cryomilling (in the first 15 min of dissolution test) in comparison to the vitrified drug. Furthermore, we showed that cryogrinding of the crystalline BOS monohydrate leads to the formation of a nearly anhydrous amorphous sample. This finding, different from that reported by Megarry et al. [ Carbohydr. Res. 2011, 346, 1061-1064] for trehalose (TRE), was revealed on the basis of infrared and thermal measurements. Finally, two various hypotheses explaining water removal upon cryomilling have been discussed in the manuscript.

Effects of Concomitant Administration of PXR Ligand Drugs on the Anticoagulant Effects of Warfarin.

We encountered cases in which the anticoagulant effects of warfarin (CYP2C9 substrate) were reversibly attenuated by the concomitant administration of rifampicin or bosentan, which are potent pregnane X receptor (PXR) ligands. The purpose of the present study is to report the previous case with rifampicin, and to evaluate the changes in the warfarin anticoagulant effects when withdrawing or switching bosentan treatment. The former is a case study of a 4-year-old girl undergoing warfarin treatment. The latter is a longitudinal study of 20 pediatric patients receiving stable warfarin treatment. The prothrombin time and international normalized ratio (PT-INR) values were extracted from the medical records and normalized by the daily-dose per body size as an index for the warfarin anticoagulant effects. Rifampicin treatment resulted in a 52.0% decrease in the anticoagulant index. On the other hand, 10 of 20 patients started bosentan and their anticoagulant index was reduced by a median of 2.00. Bosentan was withdrawn in 4 of 20 patients and their anticoagulant index increased by a median of 3.67. Six of 20 patients switched from bosentan to macitentan, which is considered not to activate PXR in clinical settings. However, switching from bosentan to macitentan resulted in a median of 2.25 reduction of the anticoagulant index rather than recovery of the response to warfarin. This study suggests not only the possibility of heterogeneity in the response to PXR activation and deactivation, but also the importance of long-term monitoring of drug-drug interactions when switching from bosentan to macitentan.

Efficacy and safety of bosentan in the treatment of persistent pulmonary hypertension of the newborn: a Metaanalysis. / æ³¢ç”Ÿå¦æ²»ç–—æ–°ç”Ÿå„¿æŒç»­æ€§è‚ºåŠ¨è„‰é«˜åŽ‹æœ‰æ•ˆæ€§åŠå®‰å ¨æ€§çš„Meta分析.

OBJECTIVES: To systematically evaluate the efficacy and safety of bosentan in the treatment of persistent pulmonary hypertension of the newborn (PPHN). METHODS: Chinese Journal Full-text Database, Weipu Database, Wanfang Data, China Biology Medicine disc, PubMed, Web of Science, Embase, and Cochrane Library were searched for literature on bosentan in the treatment of PPHN published up to August 31, 2021. RESULTS: A total of 8 randomized controlled trials were included for Meta analysis. The results of the Meta analysis showed that compared with the control group, the bosentan treatment group had a significantly lower treatment failure rate (RR=0.23, P<0.001), a significantly greater reduction in pulmonary artery pressure [mean difference (MD)=-11.79, P<0.001)], significantly greater increases in oxygen partial pressure (MD=10.21, P=0.006) and blood oxygen saturation (MD=8.30, P<0.001), and a significantly shorter length of hospital stay (MD=-1.35, P<0.001). The descriptive analysis showed that the bosentan treatment group had a lower degree of tricuspid regurgitation than the control group after treatment. The main adverse reactions of bosentan treatment included abnormal liver function, anemia and edema. The results of subgroup analysis based on treatment regimen, research area, and drug dose were consistent with those before stratification. CONCLUSIONS: Bosentan is effective in the treatment of PPHN. However, when using bosentan, attention should be paid to adverse reactions such as abnormal liver function.

Effect of endothelin on sex-dependent regulation of tone in coronary resistance vessels.

BACKGROUND/AIMS: Sex dependent differences in coronary artery vasoregulation may be due to variations in responses to endogenous vasoactive compounds including endothelin (ET-1) and nitric oxide (NO). METHODS: Septal coronary arteries (<200 µm) from healthy, sexually mature male, female and ovariectomized (i.e. surgical menopause) Sprague-Dawley rats were used. Myogenic tone, measured by pressure myography, was initially determined for all vessel segments studied before and after exposure to the nonselective ETA/ETB receptor blocker, bosentan (1 µM). Vasoconstrictor responses (vascular endothelium intact) to cumulative ET-1 (10-12 - 10-9 M) were assessed in a separate set of septal coronary vessels. Additional studies, examined the vasoconstrictor effects of ET-1 after NO blockade with L-NAME (200 µM). RESULTS: Myogenic tone was 26 ± 7% in male, 20 ± 7% in female (p = 0.04 versus male) and 24 ± 3% in ovariectomized (p = NS versus male/female) vessels. Antagonism of ET-1 receptors produced a greater reduction in myogenic tone in male, compared to female rats over a similar range of intraluminal pressure (20-80 mmHg). Robust constrictor responses to cumulative concentrations of ET-1 were observed in all vessels; however, male rats exhibited greater sensitivity to vasoconstrictor effects of ET-1. After exposure to L-NAME vessel responses to ET-1 were normalized in male and female (not studied in ovariectomized) groups. CONCLUSIONS: These findings confirm marked sex differences for myogenic tone and vessel constrictor responses to ET-1 in coronary resistance vessels. Results also suggest greater sensitivity to vasoconstrictor effects of ET-1 in male coronary resistance vessels.

Evaluation of the combination of endothelin receptor antagonists (ERA) and phosphodiesterase-5 inhibitors for the treatment of pulmonary arterial hypertension (PAH) in pathologic human pulmonary arteries in an ex-vivo organ bath model.

PURPOSE: Medical combination therapy of pulmonary arterial hypertension (PAH) may alleviate the drawbacks of monotherapy by avoiding drug tolerance and by increasing effectiveness, as shown by the combination of ambrisentan and tadalafil (AMBITION trial). The present ex-vivo study evaluated the combination of the endothelin receptor antagonists (ERA) macitentan and bosentan with the phosphodiesterase-5 (PDE-5) inhibitor vardenafil in pulmonary arteries from patients suffering from terminal lung disease as a model of PAH. METHODS: Segments of the pulmonary vessels were excised from resected lungs of patients requiring lung transplantation (LTX). Contraction of pulmonary arteries (PA) was elicited by consecutive dose-response curves of endothelin-1 (ET-1) followed by norepinephrine (NE) to allow inhibition by different pathways. Forces were measured isometrically in an organ bath in the presence and absence of ERA and PDE-5 inhibitors and their combination. RESULTS: PA of 38 patients were examined between October 2016 and November 2019. Bosentan (1E-7 M) and macitentan (1E-8 M, 3E-8 M, 1E-7 M) inhibited ET-1 induced contractions, whereas vardenafil (1E-6 M, 3E-6 M, 1E-5 M) inhibited only the NE induced part of the contractions. Vardenafil enhanced bosentan-induced inhibition of vasoconstriction in a dose-dependent fashion. Combination effects exceeded single bosentan at 3E-6 M and 1E-5 M vardenafil, and they exceeded single vardenafil at the lower vardenafil concentrations. Macitentan showed a more pronounced inhibition than bosentan regardless of the lower concentrations. Accordingly, combination effects with vardenafil resembled those of macitentan alone. CONCLUSIONS: Macitentan and bosentan were potent antagonists of vasoconstriction in PA of LTX patients. The benefit of drug combinations was demonstrated at selected concentrations only owing to a narrow therapeutic range of vardenafil in this ex-vivo model. These results suggest the utility of drug combinations other than the established pair of ambrisentan and tadalafil in PAH treatment but also make a case for a further assessment of vasodilator properties of drugs complementing ERA.

The Influence of Bosentan on MicroRNA-27a/PPARγ/ET-1 Signaling Pathway in Pulmonary Artery Hypertension.

Pulmonary artery hypertension (PAH) is a common and serious disease which is characterized by pulmonary vascular remodeling. Bosentan (BST) is the first approved oral targeted drug of endothelin-1 (ET-1) receptor antagonists for the treatment of PAH. MicroRNA-27a (miR-27a) and peroxisome proliferator-activated receptor γ (PPARγ) were found to be related to the pathogenesis of PAH. To further explore the signal transduction mechanism of BST in the treatment of PAH, we examined the effects of BST on endothelin receptors, miR-27a, and PPARγ. Meanwhile, the influence of miR-27a in the formation and development of PAH was discussed. Our results demonstrated that during the pathophysiology of PAH, miR-27a, PPARγ, and ET-1 were cross-inhibited, which indicated that the miR-27a/PPARγ/ET-1 signaling pathway was dysregulated; in addition, BST could competitively bind to ET-1 receptors and inhibit the miR-27a/PPARγ/ET-1 signaling pathway, thereby delaying the proliferation of PASMCs and affecting the development of PAH. Our results give a new understanding of the pathogenesis and treatment of PAH and provide more reliable evidence for the application of BST in the treatment of PAH in the clinic.

Primary Human Hepatocyte Spheroids as Tools to Study the Hepatotoxic Potential of Non-Pharmaceutical Chemicals.

Drug-induced liver injury, including cholestasis, is an important clinical issue and economic burden for pharmaceutical industry and healthcare systems. However, human-relevant in vitro information on the ability of other types of chemicals to induce cholestatic hepatotoxicity is lacking. This work aimed at investigating the cholestatic potential of non-pharmaceutical chemicals using primary human hepatocytes cultured in 3D spheroids. Spheroid cultures were repeatedly (co-) exposed to drugs (cyclosporine-A, bosentan, macitentan) or non-pharmaceutical chemicals (paraquat, tartrazine, triclosan) and a concentrated mixture of bile acids for 4 weeks. Cell viability (adenosine triphosphate content) was checked every week and used to calculate the cholestatic index, an indicator of cholestatic liability. Microarray analysis was performed at specific time-points to verify the deregulation of genes related to cholestasis, steatosis and fibrosis. Despite the evident inter-donor variability, shorter exposures to cyclosporine-A consistently produced cholestatic index values below 0.80 with transcriptomic data partially supporting its cholestatic burden. Bosentan confirmed to be hepatotoxic, while macitentan was not toxic in the tested concentrations. Prolonged exposure to paraquat suggested fibrotic potential, while triclosan markedly deregulated genes involved in different types of hepatotoxicity. These results support the applicability of primary human hepatocyte spheroids to study hepatotoxicity of non-pharmaceutical chemicals in vitro.

Blockade of endothelin receptor A enhances the therapeutic efficacy of gemcitabine in pancreatic cancer cells.

Pancreatic adenocarcinoma is currently one of the leading causes of cancer-related death worldwide. The high rate of mortality in pancreatic cancer patients is due to the inability to detect early-stage disease and the disease being highly refractory to therapy. Gemcitabine has been the standard chemotherapy for advanced pancreatic cancer patients for the last two decades. However, gemcitabine resistance develops within a few weeks of treatment, and the associated mechanism remains poorly understood. Therefore, a novel therapeutic strategy is needed to overcome the limited clinical efficacy of gemcitabine in pancreatic adenocarcinoma. In this study, we demonstrated that ET-1/ETAR axis gene expression was upregulated in pancreatic cancer cells after treatment with gemcitabine. Additionally, ETAR expression was significantly higher in tumor tissues than in normal tissues, and patients with high ETAR expression had a notably worse overall survival rate than those with low ETAR expression. Furthermore, our results revealed that bosentan, an ETAR antagonist, enhanced the growth-inhibiting and proapoptotic effects of gemcitabine on pancreatic cancer cells. Thus, our findings indicate that blockade of the ET-1/ETAR axis signaling pathway promotes the antiproliferative effect of gemcitabine on pancreatic cancer. Therefore, combination of ETAR blockade and gemcitabine serves as an effective therapeutic approach to achieve clinical benefits in pancreatic adenocarcinoma patients.

Predictive model of bosentan-induced liver toxicity in Japanese patients with pulmonary arterial hypertension.

Bosentan, an endothelin receptor antagonist, has been widely used as a first-line medication for the treatment of pulmonary arterial hypertension (PAH). It has been shown to improve symptoms of hypertension, exercise capacity, and hemodynamics and prolong time to clinical worsening. However, liver dysfunction is a major side effect of bosentan treatment that could hamper the optimal management of patients with PAH. Previously, we demonstrated, using drug metabolism enzymes and transporters analysis, that the carbohydrate sulfotransferase 3 (CHST3) and CHST13 alleles are significantly more frequent in patients with elevated aminotransferases during therapy with bosentan than they are in patients without liver toxicity. In addition, we constructed a pharmacogenomics model to predict bosentan-induced liver injury in patients with PAH using two single-nucleotide polymorphisms and two nongenetic factors. The purpose of the present study was to externally validate the predictive model of bosentan-induced liver toxicity in Japanese patients. We evaluated five cases of patients treated with bosentan, and one presented with liver dysfunction. We applied mutation alleles of CHST3 and CHST13, serum creatinine, and age to our model to predict liver dysfunction. The sensitivity and specificity were calculated as 100% and 50%, respectively. Considering that PAH is a rare disease, multicenter collaboration would be necessary to validate our model.

Comparison of the inhibitory effect of ketoconazole, voriconazole, fluconazole, and itraconazole on the pharmacokinetics of bosentan and its corresponding active metabolite hydroxy bosentan in rats.

1. This study aimed to investigate the inhibitory effect of azole antifungal agents, including ketoconazole, voriconazole, fluconazole, and itraconazole, on the pharmacokinetics of bosentan (BOS) and its active metabolite hydroxy bosentan (OHBOS) in Sprague-Dawley (SD) rats.2. A total of 25 healthy male SD rats were divided into five groups and treated with various azole antifungal agents by gavage, followed by a single dose of BOS after 30 min.3. The study found that ketoconazole led to a significant increase (5.1-fold) in the AUC(0-t) of BOS, associated with a 5.8-fold elevation in the Cmax, which was greater than that for fluconazole (2.6- and 2.9-fold) and voriconazole (1.1- and 1.7-fold). Accordingly, the Vz/F and CLz/F of BOS reduced by 89.2% and 83.7%, respectively, on administering ketoconazole concomitantly. However, fluconazole caused a decrease in Vz/F and CLz/F by 77.4% and 72.2%, respectively, compared with voriconazole that exhibited a decrease in CLz/F by 51.7% with a negligible change in Vz/F. Also, obvious differences were observed in the pharmacokinetic parameters of OHBOS between the control and treated groups.4. Collectively, treatment with ketoconazole resulted in a prominent inhibitory effect on the metabolism of BOS, followed by treatment with fluconazole, voriconazole, and itraconazole. Therefore, these details of animal studies may help draw more attention to the safety of BOS while combining it with ketoconazole, voriconazole, fluconazole, or itraconazole clinically.

Clinical efficacy and safety of switch from bosentan to macitentan in children and young adults with pulmonary arterial hypertension: extended study results.

BACKGROUND: Macitentan is an orally active, potent, dual endothelin receptor antagonist and is the only registered treatment for pulmonary arterial hypertension that significantly reduced morbidity and mortality in a long-term study. AIM: We have recently reported that switch from bosentan to macitentan significantly improved exercise capacity in children and young adults with pulmonary arterial hypertension in a 24-week prospective study and well tolerated without adverse events. We now aimed to evaluate clinical efficacy, safety of switch in a larger patient population, in a 24-month prospective study. METHODS: This is a single-institution, 24-month prospective study. Patients ≥12 years with idiopathic/heritable, pulmonary arterial hypertension, or related to CHD or residual pulmonary arterial hypertension due to repaired congenital systemic-to-pulmonary shunts and on bosentan treatment were included. Concomitant treatment with oral phosphodiesterase type 5 inhibitors/inhaled prostanoids was allowed. Outcome measures included change from baseline to 24 months, in the 6-minute walk distance, functional class, oxygen saturation at rest/after walk distance test, and natriuretic peptide levels. Safety end points included adverse events, laboratory abnormalities. RESULTS: Twenty-seven patients (19 adults/8 children, mean age: 21.1 ± 6.3 years (12-36), weight: 53.1 ± 15.7 kgs (26-87)) were included. Mean duration of macitentan treatment: 22.3 ± 3.9 months (9-24). Six-minute walk distance significantly improved from baseline (mean: 458 ± 79 m (300-620)) at 6 months (mean: 501 ± 73 m (325-616) + 43 m) (p < 0.05), at 12 months (mean: 514 ± 82 m (330-626) + 56 m) (p < 0.05), and at 24 months (mean: 532 ± 85 m (330-682) + 74 m) (p < 0.05). We observed a significant improvement during the first 6 months but no incremental improvement after 6 months (p > 0.05). Macitentan did not significantly change functional class, oxygen saturation, and natriuretic levels (p > 0.05). None of the patients had anaemia, hepatotoxicity, and peripheral edema. CONCLUSIONS: Our study is the first study which showed that switch from bosentan to macitentan improved exercise capacity in children and young adults with pulmonary arterial hypertension significantly in the first 6 months and compared to baseline in 24 months and well tolerated without adverse events.

The Clinical Efficacy of Endothelin Receptor Antagonists in Patients with Pulmonary Arterial Hypertension.

Therapeutic strategies for pulmonary arterial hypertension (PAH) have made remarkable progress over the last two decades. Currently, 3 types of drugs can be used to treat PAH; prostacyclins, phosphodiesterase 5 inhibitors, and endothelin receptor antagonists (ERA). In Japan, the first generation ERA bosentan was reimbursed in 2005, following which the 2nd generation ERAs ambrisentan and macitentan were reimbursed in 2009 and 2015, respectively. The efficacy of each ERA on hemodynamics in PAH patients remains to be elucidated. The aims of this study were to evaluate the hemodynamic effects of ERAs and compare these effects among each generation of ERAs.We retrospectively examined the clinical parameters of 42 PAH patients who were prescribed an ERA (15 bosentan, 12 ambrisentan, and 15 macitentan) and who underwent a hemodynamic examination before and after ERA introduction at our institution from January 2007 to July 2019.In a total of 42 patients, mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) were significantly decreased and cardiac index was significantly increased after ERA introduction (P < 0.001) and the World Health Organization-Functional class (WHO-Fc) was significantly improved after ERA introduction (P = 0.005). Next, in a comparison between 1st and 2nd generation ERAs, 2nd generation ERAs were found to have brought about greater improvements in hemodynamic parameters (mPAP and PVR. P < 0.01), heart rate, brain natriuretic peptide, arterial oxygen saturation, and mixed venous oxygen saturation than the 1st generation ERA bosentan.We conclude that all ERAs could successfully improve the hemodynamics of PAH patients and that the newer generation ERAs, ambrisentan and macitentan, seemed to be preferable to bosentan.