New trial designs and potential therapies for pulmonary artery hypertension

Designing acute kidney injury clinical trials

Acute kidney injury (AKI) is a common clinical condition with various causes and is associated with increased mortality. Despite advances in supportive care, AKI increases not only the risk of premature death compared with the general population but also the risk of developing chronic kidney disease and progressing towards kidney failure. Currently, no specific therapy exists for preventing or treating AKI other than mitigating further injury and supportive care. To address this unmet need, novel therapeutic interventions targeting the underlying pathophysiology must be developed. New and well-designed clinical trials with appropriate end points must be subsequently designed and implemented to test the efficacy of such new interventions. Herein, we discuss predictive and prognostic enrichment strategies for patient selection, as well as primary and secondary end points that can be used in different clinical trial designs (specifically, prevention and treatment trials) to evaluate novel interventions and improve the outcomes of patients at a high risk of AKI or with established AKI.

Ligustrazine alleviates pulmonary arterial hypertension in rats by promoting the formation of myocardin transcription complex in the nucleus of pulmonary artery smooth muscle cells

Pulmonary arterial hypertension (PAH) is a pathophysiological state of abnormally elevated pulmonary arterial pressure caused by drugs, inflammation, toxins, viruses, hypoxia, and other risk factors. We studied the therapeutic effect and target of tetramethylpyrazine (tetramethylpyrazine [TMP]; ligustrazine) in the treatment of PAH and we speculated that dramatic changes in myocardin levels can significantly affect the progression of PAH. In vivo, the results showed that administration of TMP significantly prolonged the survival of PAH rats by reducing the proliferative lesions, right ventricular systolic pressure (RVSP), mean pulmonary arterial pressure (mPAP), and the Fulton index in the heart and lung of PAH rats. In vitro, TMP can regulate the levels of smooth muscle protein 22-alpha (SM22-α), and myocardin as well as intracellular cytokines such as NO, transforming growth factor beta (TGF-β), and connective tissue growth factor (CTGF) in a dose-dependent manner (25, 50, or 100 μM). Transfection of myocardin small interfering RNA (siRNA) aggravated the proliferation of pulmonary artery smooth muscle cells (PSMCs), and the regulatory effect of TMP on α-smooth muscle actin (α-SMA) and osteopontin (OPN) disappeared. The application of 10 nM estrogen receptor alpha (ERα) inhibitor MPP promoted the proliferation of PSMCs, but it does not affect the inhibition of TMP on PSMCs proliferation. Finally, we found that TMP promoted the nucleation of myocardin-related transcription factor-A (MRTF-A) and combined it with myocardin. In conclusion, TMP can inhibit the transformation of PSMCs from the contractile phenotype to the proliferative phenotype by promoting the formation of the nuclear (MRTF-A/myocardin) transcription complex to treat PAH.

Mammalian Ste20-like kinase 1 inhibition as a cellular mediator of anoikis in mouse bone marrow mesenchymal stem cells

BACKGROUND

The low survival rate of mesenchymal stem cells (MSCs) caused by anoikis, a form of apoptosis, limits the therapeutic efficacy of MSCs. As a proapoptotic molecule, mammalian Ste20-like kinase 1 (Mst1) can increase the production of reactive oxygen species (ROS), thereby promoting anoikis. Recently, we found that Mst1 inhibition could protect mouse bone marrow MSCs (mBMSCs) from H₂O₂-induced cell apoptosis by inducing autophagy and reducing ROS production. However, the influence of Mst1 inhibition on anoikis in mBMSCs remains unclear.

AIM

To investigate the mechanisms by which Mst1 inhibition acts on anoikis in isolated mBMSCs.

METHODS

Poly-2-hydroxyethyl methacrylate-induced anoikis was used following the silencing of Mst1 expression by short hairpin RNA (shRNA) adenovirus transfection. Integrin (ITGs) were tested by flow cytometry. Autophagy and ITGα5β1 were inhibited using 3-methyladenine and small interfering RNA, respectively. The alterations in anoikis were measured by Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling and anoikis assays. The levels of the anoikis-related proteins ITGα5, ITGβ1, and phospho-focal adhesion kinase and the activation of caspase 3 and the autophagy-related proteins microtubules associated protein 1 light chain 3 II/I, Beclin1 and p62 were detected by Western blotting.

RESULTS

In isolated mBMSCs, Mst1 expression was upregulated, and Mst1 inhibition significantly reduced cell apoptosis, induced autophagy and decreased ROS levels. Mechanistically, we found that Mst1 inhibition could upregulate ITGα5 and ITGβ1 expression but not ITGα4, ITGαv, or ITGβ3 expression. Moreover, autophagy induced by upregulated ITGα5β1 expression following Mst1 inhibition played an essential role in the protective efficacy of Mst1 inhibition in averting anoikis.

CONCLUSION

Mst1 inhibition ameliorated autophagy formation, increased ITGα5β1 expression, and decreased the excessive production of ROS, thereby reducing cell apoptosis in isolated mBMSCs. Based on these results, Mst1 inhibition may provide a promising strategy to overcome anoikis of implanted MSCs.

Circ-calm4 regulates hypoxia-induced pulmonary artery smooth muscle autophagy by binding Purb

Pulmonary hypertension (PH) is a serious and fatal disease characterized by pulmonary vasoconstriction and pulmonary vascular remodeling. The excessive autophagy of pulmonary artery smooth muscle cells (PASMCs) is one of the important factors of pulmonary vascular remodeling. A number of studies have shown that circular RNA (circRNA) can participate in the onset of PH. Our previous studies have shown that circRNA calmodulin 4 (circ-calm4) is involved in the progression of hypoxic PH. However, the role of circ-calm4 on regulation of hypoxic PH autophagy has not been reported. In this study, we demonstrated for the first time that hypoxia-mediated upregulated circ-calm4 expression has a key regulatory effect on autophagy in hypoxia-induced PASMCs and hypoxic PH mouse models. Knockdown of circ-calm4 both in vivo and in vitro can inhibit the autophagy in PASMCs induced by hypoxia. We also performed bioinformatics predictions and conducted experiments to verify that circ-calm4 bound to the purine-rich binding protein (Purb) to promote its expression in the nucleus, thereby initiating the transcription of autophagy-related protein Beclin1. Interestingly, we found that Beclin1 transcription initiated by Purb was accompanied by a modification of Beclin1 super-enhancer to improve transcription activity and efficiency. Overall, our results confirm that the circ-calm4/Purb/Beclin1 signal axis is involved in the occurrence of hypoxia-induced PASMCs autophagy, and the novel regulatory mechanisms and signals transduction pathways in PASMC autophagy induced by hypoxia.

Efficacy, safety, and pharmacokinetics of inhaled treprostinil in Japanese patients with pulmonary arterial hypertension

Treprostinil is a chemically stable analog of prostacyclin, and inhaled treprostinil was developed to deliver the effects directly to the pulmonary vasculature while minimizing systemic side effects. The objective of the study was to evaluate the efficacy on hemodynamics and exercise capacity, safety, and pharmacokinetics (PK) of inhaled treprostinil in Japanese patients with pulmonary arterial hypertension (PAH). Inhaled treprostinil was administered at three breaths (18 μg)/session four times daily, and the dose was gradually increased to a maximum of nine breaths (54 μg)/session. Endpoints included change in pulmonary vascular resistance index (PVRI) as primary, other efficacy parameters, safety, and PK. Seventeen PAH patients, the majority of whom (76.5%) had been receiving both an endothelin receptor antagonist (ERA) and a phosphodiesterase type-5 (PDE5) inhibitor/soluble guanylate cyclase (sGC) stimulator, received inhaled treprostinil. At Week 12, PVRI statistically decreased by -39.4 ± 25.5% (95% confidence interval: -52.6 to -26.3). The most frequently reported adverse events related to treprostinil were headache, cough, throat irritation, and hot flush. Regarding PK, there were no notable differences in the geometric mean C _max and AUC_last between Japanese and non-Japanese patients. Treatment with inhaled treprostinil using the dosing regimen approved in the United States resulted in significant improvement in hemodynamics, exercise capacity, and symptoms with a favorable tolerability and safety profile in Japanese patients. Inhaled treprostinil could be a valuable therapeutic option for Japanese patients with PAH, including those receiving a combination therapy with an ERA and a PDE5 inhibitor/sGC stimulator. Trial registration: JAPIC Clinical Trials Information [JapicCTI-194651].

Dynamics of 6-Minute Walk Distance as a Predictor of Efficiency Specific Pulmonary Vasodilators

Pulmonary hypertension is a severe and often rapidly progressive disease with a fatal outcome. Approved specific therapy with five classes of drugs – prostanoids, endothelin receptor antagonists, phosphodiesterase-5 inhibitors, soluble guanylate cyclase stimulators and prostacyclin receptor agonists has significantly improved the prognosis of patients. An accessible and reproducible criterion of exercise tolerance – a distance walked in six-minute walk test (6MXD) – occupies one of the central places among the performance indicators (clinical, echocardiographic and hemodynamic) of specific pulmonary vasodilators. Reflecting the clinical severity of pulmonary hypertension and, according to some data, its long-term prognosis, the dynamics of 6MXD is an integral component of the combined primary endpoints of randomized controlled trials. In the CHEST-2019 recommendations, the dynamics of the 6MXD was used to standardize the randomized controlled trials. The 6MXD is indispensable for dynamic observation and decisionmaking on further treatment tactics 

Comparison of Healthcare Encounters and Drug Persistence in Patients With Pulmonary Arterial Hypertension Receiving Oral Selexipag, Inhaled Iloprost, or Parenteral Treprostinil: A Retrospective Database Analysis

Background: Agents targeting the prostacyclin (PGI₂) pathway are important in managing pulmonary arterial hypertension (PAH). No head-to-head clinical trials have compared outcomes between the 3 different PGI₂-pathway drugs most commonly available in countries with advanced healthcare: oral selexipag, inhaled iloprost, and parenteral (subcutaneous or intravenous) treprostinil. Objectives: To conduct retrospective database analyses to describe characteristics of patients with PAH initiating therapy with these agents and compare the rate and risk of healthcare facility encounters and drug persistence. Methods: Data were obtained from the Optum™ Clinformatics® Data Mart and Truven™ Health Analytics® MarketScan® Commercial Claims and Encounters databases from July 1, 2008, to September 30, 2020 (Optum™), or October 31, 2020 (Truven™). Patients were categorized into index-drug cohorts based on first pharmacy claims for selexipag, inhaled iloprost, or parenteral treprostinil. Eligible patients were ≥18 years of age with ≥1 ICD-9-CM or ICD-10-CM diagnosis code indicating pulmonary hypertension and no diagnosis code suggesting Group 3-5 pulmonary hypertension. Rates of hospitalization (inpatient admissions), emergency room visits, or outpatient visits per person-year were calculated. Drug persistence was measured as time to discontinuation of index drug. Multivariable analyses were performed to compare outcomes with selexipag vs inhaled iloprost and parenteral treprostinil, adjusting for baseline characteristics using inverse probability of treatment weighting. Results: Overall, 583 patients were included in the Optum™ sample and 482 in the Truven™ sample. Mean (SD) age was 61.7 (14.5) and 49.3 (11.3) years, respectively; 74.4% and 75.7% of patients, respectively, were women. In the pooled samples, after adjustment for baseline characteristics, selexipag had a lower risk than inhaled iloprost or parenteral treprostinil for hospitalization (relative rate ratio [95% CI], 0.40 [0.22, 0.75], and 0.26 [0.17, 0.39]) and outpatient visits (0.66 [0.56, 0.78] and 0.76 [0.66, 0.88]). Trends toward lower risk of emergency room visits did not attain statistical significance. Drug discontinuation risk was 16% and 36% lower with selexipag vs parenteral treprostinil and inhaled iloprost, respectively. Conclusions: In real-world use, selexipag appears to be associated with lower rates of hospitalization and outpatient visits than inhaled iloprost or parenteral treprostinil. Further research is required to identify factors underlying these differences.

LncPTSR Triggers Vascular Remodeling in Pulmonary Hypertension by Regulating [Ca2+]i in Pulmonary Arterial Smooth Muscle Cells

Pulmonary hypertension (PH) is characterized by vascular remodeling and sustained increase in right ventricular systolic pressure (RVSP). The molecular mechanisms behind PH development remain unclear. Here, a long non-coding RNA (lncRNA) attenuated by platelet-derived growth factor BB (PDGF-BB) was identified and its functional roles were investigated in vitro and in vivo. Using RNA-seq data and rapid amplification of cDNA ends, a lncRNA neighboring the locus of plasma membrane calcium transporting ATPase 4 (PMCA4) was identified and named lncPTSR. It is a highly-conserved nuclear lncRNA, and was downregulated in pulmonary arterial smooth muscle cells (PASMCs) with PDGF-BB stimulation or hypoxia induction. Gene interruption/overexpression assays revealed that lncPTSR negatively regulates rat PASMCs proliferation, apoptosis, and migration. LncPTSR interruption in Sprague Dawley (SD) rats using adenovirus associated virus type 9 (AAV9)-mediated short-hairpin RNA (shRNA) resulted in a significant increase in RVSP and vascular remodeling in normoxic condition. LncPTSR knockdown also suppressed PMCA4 expression and attenuated the intracellular Ca2+ efflux of PASMCs in vitro and in vivo. Further studies suggest a complex cross-talk between lncPTSR and mitogen-activated protein kinase (MAPK) pathway: inhibition of mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated kinase (ERK) abolishes the PDGF-BB-mediated lncPTSR downregulation, and lncPTSR plays a feedback regulation for MAPK signaling molecules. The present study suggests that lncPTSR participates in pulmonary artery (PA) remodeling via modulating the expression of PMCA4 and intracellular Ca2+ homeostasis downstream of PDGF-BB driven MEK/ERK signaling. These results suggest lncPTSR may be a promising therapeutic target in PH treatment.

Bioactivities and mechanisms of natural medicines in the management of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive and rare disease without obvious clinical symptoms that shares characteristics with pulmonary vascular remodeling. Right heart failure in the terminal phase of PAH seriously threatens the lives of patients. This review attempts to comprehensively outline the current state of knowledge on PAH its pathology, pathogenesis, natural medicines therapy, mechanisms and clinical studies to provide potential treatment strategies. Although PAH and pulmonary hypertension have similar pathological features, PAH exhibits significantly elevated pulmonary vascular resistance caused by vascular stenosis and occlusion. Currently, the pathogenesis of PAH is thought to involve multiple factors, primarily including genetic/epigenetic factors, vascular cellular dysregulation, metabolic dysfunction, even inflammation and immunization. Yet many issues regarding PAH need to be clarified, such as the "oestrogen paradox". About 25 kinds monomers derived from natural medicine have been verified to protect against to PAH via modulating BMPR2/Smad, HIF-1α, PI3K/Akt/mTOR and eNOS/NO/cGMP signalling pathways. Yet limited and single PAH animal models may not corroborate the efficacy of natural medicines, and those natural compounds how to regulate crucial genes, proteins and even microRNA and lncRNA still need to put great attention. Additionally, pharmacokinetic studies and safety evaluation of natural medicines for the treatment of PAH should be undertaken in future studies. Meanwhile, methods for validating the efficacy of natural drugs in multiple PAH animal models and precise clinical design are also urgently needed to promote advances in PAH.

The Differentiation of Pluripotent Stem Cells towards Endothelial Progenitor Cells - Potential Application in Pulmonary Arterial Hypertension

Background and Objectives

Endothelial progenitor cells (EPCs) and endothelial cells (ECs) have been applied in the clinic to treat pulmonary arterial hypertension (PAH), a disease characterized by disordered pulmonary vasculature. However, the lack of sufficient transplantable cells before the deterioration of disease condition is a current limitation to apply cell therapy in patients. It is necessary to differentiate pluripotent stem cells (PSCs) into EPCs and identify their characteristics.

Methods and Results

Comparing previously reported methods of human PSCs-derived ECs, we optimized a highly efficient differentiation protocol to obtain cells that match the phenotype of isolated EPCs from healthy donors. The protocol is compatible with chemically defined medium (CDM), it could produce a large number of clinically applicable cells with low cost. Moreover, we also found PSCs-derived EPCs express CD133, have some characteristics of mesenchymal stem cells and are capable of homing to repair blood vessels in zebrafish xenograft assays. In addition, we further revealed that IPAH PSCs-derived EPCs have higher expression of proliferation-related genes and lower expression of immune-related genes than normal EPCs and PSCs-derived EPCs through microarray analysis.

Conclusions

In conclusion, we optimized a highly efficient differentiation protocol to obtain PSCs-derived EPCs with the phenotypic and molecular characteristics of EPCs from healthy donors which distinguished them from EPCs from PAH.

The benefit of exercise-based rehabilitation programs in patients with pulmonary hypertension: a systematic review and meta-analysis of randomized controlled trials

Several studies have suggested that exercise capacity and quality of life are reduced in patients with pulmonary hypertension, and exercise-based rehabilitation can improve exercise capacity and quality of life in patients with pulmonary hypertension. The aim of this study is to assess the efficacy and safety of exercise-based rehabilitation in patients with pulmonary hypertension through a meta-analysis of randomized controlled trials. We searched PubMed, Embase, Medline, and the Cochrane Central Register of Controlled Trials up to November 2018. All randomized controlled trials comparing exercise capacity and quality of life between patients undergoing exercise-based rehabilitation and those undergoing non-exercise training were included. Data were extracted separately and independently by two investigators, and discrepancies were arbitrated by the third investigator. We used the random-effects model to analyze the results, the GRADE to assess the risk of bias in the included studies, and I² statistic to estimate the degree of heterogeneity. Nine randomized controlled trials are included; however, only seven randomized controlled trials were able to extract data. Including inpatients and outpatients, the total number of participants was 234, most of whom were diagnosed as pulmonary artery hypertension. The study duration ranged from 3 to 15 weeks. The mean six-minute walking distance after exercise training was 51.94 m higher than control (27.65-76.23 m, n = 234, 7 randomized controlled trials, low quality evidence), the mean peak oxygen uptake was 2.96 ml/kg/min higher (2.49-3.43 ml/kg/min, n = 179, 4 randomized controlled trials, low-quality evidence) than in the control group. In conclusion, our finding suggests that an exercise-based training program positively influences exercise capacity in patients with pulmonary hypertension.

Activation of AMPK inhibits Galectin-3-induced pulmonary artery smooth muscle cells proliferation by upregulating hippo signaling effector YAP

Galectin-3(Gal-3) is an effective regulator in the pathological process of pulmonary arterial hypertension (PAH). However, the detailed mechanisms underlying Gal-3 contribution to PAH are not yet entirely clear. The aim of the present study was to explore these issues. Proliferation of rat pulmonary arterial smooth muscle cells (PASMCs) was determined using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Small interfering RNA (siRNA) was applied to silence the expression of yes-associated protein (YAP) and Forkhead box M1 (FOXM1). The protein expression and phosphorylation were measured by immunoblotting. The subcellular location of YAP was determined using immunoblotting and immunofluorescence. Gal-3-stimulated PASMCs proliferation in a time- and dose-dependent manner, this was accompanied with, YAP upregulation, dephosphorylation, and nucleus translocation. Gal-3 further increased FOXM1 and cyclinD1 expression via YAP activation. Interfering YAP/FOXM1 axis suppressed Gal-3-induced PASMCs proliferation. Activation of AMPK also inhibited Gal-3-triggered cells proliferation by targeting YAP/FOXM1/cyclinD1 pathway. Gal-3 induced PASMCs proliferation by regulating YAP/FOXM1/cyclinD1 signaling cascade, and activation of AMPK targeted on this axis and suppressed Gal-3-stimulated PASMCs proliferation. Our study provides novel therapeutic targets for prevention and treatment of PAH.

Exercise Training for Pulmonary Hypertension: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Pulmonary hypertension (PH) is a chronic disease with a notable health burden; regular exercise may improve specific health outcome measures.

OBJECTIVE

The objective of this meta-analysis was to estimate the effectiveness of exercise training for PH patients.

DATA SOURCES

PubMed, CINAHL, SportDiscuss and Google Scholar databases and reference lists of included studies were searched.

STUDY SELECTION

The selection criteria were randomized controlled trials (RCTs) employing an exercise training intervention. Data were extracted from the entered studies for analysis. The primary outcomes were peak oxygen uptake (VO_2peak), anaerobic threshold (AT), 6-minute walk distance (6-MWD), and quality of life (QoL) measures (physical component score and mental component score). The analysis included 9 articles with a total of 302 participants: intervention (n = 154), and control (n = 148).

RESULTS

In the pooled analysis, improvements were seen in: VO_2peak, mean difference (MD) 2.79 ml/kg/min (95% CI 2.00 to 3.59, p < 0.00001); AT, MD 107.83 ml/min (95% CI 39.64 to 176.00, p = 0.002); and 6-MWD, MD 46.67 meters (95% CI 32.39 to 60.96, p < 0.00001). Differences were found in the SF-36 physical component score MD 3.57 (95% CI 2.04 to 5.10, p < 0.00001) and the SF-36 mental component score MD 3.92 (95% CI 1.92 to 5.91, p = 0.001).

CONCLUSION

This meta-analysis demonstrates exercise training has a beneficial effect on fitness, walking performance, and self-reported QoL in PH patients.

Comparative effectiveness of oral prostacyclin pathway drugs on hospitalization in patients with pulmonary hypertension in the United States: a retrospective database analysis

Two oral medications targeting the prostacyclin pathway are available to treat pulmonary arterial hypertension in the United States: oral treprostinil and selexipag. We compared real-world hospitalization in patients receiving these medications. A retrospective administrative claims study was conducted using the Optum® Clinformatics® Data Mart database. Patients with pulmonary hypertension were identified using diagnostic codes. Cohort inclusion required age ≥ 18 years, first oral treprostinil or selexipag prescription between 1 January 2015 and 30 September 2017 (index date), and continuous enrollment in the prior ≥6 months. Patients who switched index drug were excluded. Follow-up was from index date until the first of end of index drug exposure, end of continuous enrollment, death, or 31 December 2017. Multivariable Cox proportional hazard and Poisson regression were used to compare risk and rate, respectively, of hospitalization associated with oral treprostinil vs. selexipag, adjusting for potential confounders. The study cohort included 99 patients receiving oral treprostinil and 123 receiving selexipag. Mean age was 61 years, and most patients were females (71%). Compared with oral treprostinil, selexipag was associated with a 46% lower risk of all-cause hospitalization (hazard ratio 0.54, 95% confidence interval 0.31, 0.92; P = 0.02), a 47% lower risk of pulmonary hypertension-related hospitalization (hazard ratio 0.53, 95% confidence interval 0.31, 0.93; P = 0.03), a 42% lower all-cause hospitalization rate (rate ratio 0.58, 95% confidence interval 0.39, 0.87; P = 0.01), and a 46% lower pulmonary hypertension-related hospitalization rate (rate ratio 0.54, 95% confidence interval 0.35, 0.82; P = 0.004). This study suggests that selexipag is associated with lower hospitalization risk and rate than oral treprostinil.

Anticoagulation in Pulmonary Arterial Hypertension: Do We Know the Answer?

The shear stress and hypoxia in the pulmonary artery in patients with pulmonary arterial hypertension(PAH) causes endothelial dysfunction, smooth muscle proliferation and activation of thrombotic pathways leading to in situ thrombosis. Targeting the thrombotic pathways is a proposed mechanism to slow disease progression and improve survival. Over the years, the survival in patients with PAH has improved due to multiple factors with the increased use of anticoagulation as one of them. Both European Respiratory Society/European Society of Cardiology and American College of Cardiology/American Heart Association guidelines make grade II recommendations for using anticoagulation in PAH. The guidelines are based on weak observational studies with high risk of bias which have only studied warfarin as the choice of anticoagulation. In this article, we review the pathophysiology, rationale and the current literature investigating the role of anticoagulation in PAH.

Stem/Progenitor Cells and Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by endothelial dysfunction and vascular remodeling. Despite significant advancement in our understanding of the pathogenesis of PAH in recent years, treatment options for PAH are limited and their prognosis remains poor. PAH is now seen as a severe pulmonary arterial vasculopathy with structural changes driven by excessive vascular proliferation and inflammation. Perturbations of a number of cellular and molecular mechanisms have been described, including pathways involving growth factors, cytokines, metabolic signaling, elastases, and proteases, underscoring the complexity of the disease pathogenesis. Interestingly, emerging evidence suggests that stem/progenitor cells may have an impact on disease development and therapy. In preclinical studies, stem/progenitor cells displayed an ability to promote endothelial repair of dysfunctional arteries and induce neovascularization. The stem cell-based therapy for PAH are now under active investigation. This review article will briefly summarize the updates in the research field, with a special focus on the contribution of stem/progenitor cells to lesion formation via influencing vascular cell functions and highlight the potential clinical application of stem/progenitor cell therapy to PAH.

Clinical trial design in phase 2 and 3 trials for pulmonary hypertension

This article on clinical trial design incorporates the broad experience of members of the Pulmonary Vascular Research Institute's (PVRI) Innovative Drug Development Initiative (IDDI) as an open debate platform for academia, the pharmaceutical industry and regulatory experts surrounding the future design of clinical trials in pulmonary hypertension. It is increasingly clear that the design of phase 2 and 3 trials in pulmonary hypertension will have to diversify from the traditional randomised double-blind design, given the anticipated need to trial novel therapeutic approaches in the immediate future. This article reviews a wide range of differing approaches and places these into context within the field of pulmonary hypertension.

Pulmonary Arterial Hypertension-Symptoms and Impact Questionnaire: feasibility of utilizing one-day versus seven-day symptom reporting

Patient-reported outcomes are important measures to include in pulmonary arterial hypertension clinical trials but are not widely utilized in clinical practice. Pulmonary Arterial Hypertension—Symptoms and Impact Questionnaire (PAH-SYMPACT) is the only pulmonary arterial hypertension-specific patient-reported outcomes instrument developed and validated in accordance with the US Food and Drug Administration guidance on patient-reported outcomes development. The PAH-SYMPACT tool measures pulmonary arterial hypertension-related symptoms and impact of pulmonary arterial hypertension on daily life. Symptoms are reported each day for seven consecutive days, and the impact of pulmonary arterial hypertension over one week is recalled and reported on day 7; however, daily symptom reporting may overburden patients and healthcare resources, limiting the practicality of PAH-SYMPACT outside of clinical trials. To determine the practicability of an abridged version of PAH-SYMPACT for which all reporting is completed on one day, symptom data from the SYMPHONY trial (NCT01841762; PAH-SYMPACT validation study) were retrospectively analyzed to assess whether symptoms reported on each day correlated with the weekly average and whether one-day symptom scores were sensitive to disease severity. Correlation coefficients comparing the weekly average and individual day symptom scores were mostly high or very high regardless of the day they were measured. Findings were similar when using either Spearman's rank correlation or weighted kappa method. One-day symptom scores differentiated well between World Health Organization functional classes II and III/IV pulmonary arterial hypertension and were sensitive to change in disease severity as measured by the Patient Global Assessment of Disease Severity. These data suggest that the one-day PAH-SYMPACT is feasible and appropriate for routine implementation in clinical practice.

Association between splenectomy and portal hypertension in the development of pulmonary hypertension

Both portal hypertension and splenectomy are risk factors for pulmonary hypertension. However, the interactions between portal hypertension and splenectomy in the development of pulmonary hypertension remain unclear. Twelve newly diagnosed pulmonary hypertension patients with a previous history of splenectomy induced by portal hypertension were recruited between November 2008 and May 2017. We compared their clinical features, hemodynamics, and prognosis with idiopathic pulmonary arterial hypertension patients, who were matched by cardiac index, mean pulmonary arterial pressure, and pulmonary vascular resistance. We also compared the clinical characteristics of portal hypertension-post-splenectomy-pulmonary hypertension patients with eight portopulmonary hypertension patients. Compared with the matched idiopathic pulmonary arterial hypertension patients, the portal hypertension-post-splenectomy-pulmonary hypertension patients showed significantly wider red blood cell distribution width (16.7 ± 2.8% versus 13.3 ± 1.7%, p = 0.004), higher total bilirubin concentration (31.0 ± 13.8 µmol/l versus 18.9 ± 10.0 µmol/l, p = 0.010), and higher lactate dehydrogenase concentration (321.5 ± 41.2 IU/l versus 229.2 ± 69.4 IU/l, p = 0.001). Kaplan-Meier survival analyses showed that the portal hypertension-post-splenectomy-pulmonary hypertension patients tended to have poorer prognosis than the matched idiopathic pulmonary arterial hypertension patients (log-rank test: p = 0.010). Compared with the portal hypertension-post-splenectomy-pulmonary hypertension patients, the portopulmonary hypertension cohort appeared to exhibit poorer clinical conditions, including significantly lower mixed venous oxygen saturation (62.9 ± 8.0% versus 73.9 ± 6.5%, p = 0.004) and a significantly higher proportion of pericardial effusion (75.0% versus 8.3%, p = 0.004), even though the two cohorts showed similar hemodynamics. The mean intervals from diagnosis of portal hypertension to pulmonary hypertension in portopulmonary hypertension patients were significantly shorter than the intervals from splenectomy to diagnosis of pulmonary hypertension in portal hypertension-post-splenectomy-pulmonary hypertension patients (5.5 ± 5.2 years versus 13.1 ± 5.9 years, p = 0.008). Splenectomy might be involved in the initiation and development of pulmonary hypertension in patients with portal hypertension, although the precise mechanisms involved remain unknown. Portal hypertension-post-splenectomy-pulmonary hypertension patients might have poorer prognosis even with mild hemodynamics.

Pulmonary Artery Denervation as an Innovative Treatment for Pulmonary Hypertension With and Without Heart Failure

Pulmonary hypertension (PH) is categorized into 5 groups based on etiology. The 2 most prevalent forms are pulmonary arterial hypertension (PAH) and PH due to left heart disease (PH-LHD). Therapeutic options do exist for PAH to decrease symptoms and improve functional capacity; however, the mortality rate remains high and clinical improvements are limited. PH-LHD is the most common cause of PH; however, no treatment exists and the use of PAH-therapies is discouraged. Pulmonary artery denervation (PADN) is an innovative catheter-based ablation technique targeting the afferent and efferent fibers of a baroreceptor reflex in the main pulmonary artery (PA) trunk and its bifurcation. This reflex is involved in the elevation of the PA pressure seen in PH. Since 2013, both animal trials and human trials have shown the efficacy of PADN in improving PAH, including improved hemodynamic parameters, increased functional capacity, decreased PA remodeling, and much more. PADN has been shown to decrease the rate of rehospitalization, PH-related complications, and death, and is an overall safe procedure. PADN has also been shown to be effective for PH-LHD. Additional therapeutic mechanisms and benefits of PADN are discussed along with new PADN techniques. PADN has shown efficacy and safety as a potential treatment option for PH.

Medication adherence, hospitalization, and healthcare resource utilization and costs in patients with pulmonary arterial hypertension treated with endothelin receptor antagonists or phosphodiesterase type-5 inhibitors

Adherence to therapy for pulmonary arterial hypertension is essential to optimize patient outcomes, but data on real-world adherence to different pulmonary arterial hypertension drug classes are limited. This retrospective database analysis evaluated relationships between adherence, hospitalization, and healthcare costs in pulmonary arterial hypertension patients treated with endothelin receptor antagonists or phosphodiesterase type-5 inhibitors. From the IQVIA Adjudicated Health Plan Database, patients with pulmonary arterial hypertension were identified based on diagnostic codes and prescriptions for endothelin receptor antagonists (ambrisentan, bosentan, macitentan) or phosphodiesterase type-5 inhibitors (sildenafil, tadalafil) approved for pulmonary arterial hypertension. Patients were assigned to the class of their most recently initiated (index) pulmonary arterial hypertension therapy between 1 January 2009 and 30 June 2015. Medication adherence was measured by proportion of days covered; patients with proportion of days covered ≥80% were considered adherent. The proportion of adherent patients was higher for endothelin receptor antagonists (571/755; 75.6%) than for phosphodiesterase type-5 inhibitors (970/1578; 61.5%; P < 0.0001). In both groups, hospitalizations declined as proportion of days covered increased. Among adherent patients, those on endothelin receptor antagonists had a significantly lower hospitalization rate than those on phosphodiesterase type-5 inhibitors (23.1% versus 28.5%, P = 0. 0218), fewer hospitalizations (mean (standard deviation) 0.4 (0.8) versus 0.5 (0.9); P = 0.02), and mean hospitalization costs during the six-month post-index ($9510 versus $15,726, P = 0.0318). Increasing adherence reduced hospitalization risk more for endothelin receptor antagonists than for phosphodiesterase type-5 inhibitors (hazard ratio 0.176 versus 0.549, P = 0.001). Rates and numbers of rehospitalizations within 30 days post-discharge were similar between groups. Mean total costs were higher with endothelin receptor antagonists than phosphodiesterase type-5 inhibitors in all patients ($91,328 versus $72,401, P = 0.0003) and in adherent patients ($88,867 versus $56,300, P < 0.0001), driven by higher drug costs.

Plasma receptor tyrosine kinase RET in pulmonary arterial hypertension diagnosis and differentiation

Background

Pulmonary arterial hypertension (PAH) is a serious disease exhibiting unspecific symptoms, as a result of which diagnosis is often delayed and prognosis is poor. The underlying pathophysiology includes vasoconstriction and remodelling of small pulmonary arteries. As receptor tyrosine kinases (RTKs) and their ligands have been shown to promote PAH remodelling, our aim was to evaluate if their plasma levels may be utilised to differentiate between various causes of pulmonary hypertension.

Methods

28 biomarkers involved in RTK signalling were measured using proximity extension assays in venous plasma from patients with PAH (n=48), chronic thromboembolic pulmonary hypertension (CTEPH) (n=20), pulmonary hypertension due to diastolic (n=33) or systolic (n=36) heart failure and heart failure patients without pulmonary hypertension (n=15), as well as healthy controls (n=20).

Results

Plasma proto-oncogene tyrosine-protein kinase receptor Ret (RET) was decreased (p<0.04) in PAH compared with all disease groups and controls. RET generated a sensitivity of 64.6% and a specificity of 81.6% for detecting PAH from other disease groups. PAH and the other pulmonary hypertension groups showed elevated plasma tyrosine-protein kinase MER (p<0.01), vascular endothelial growth factor (VEGF)-A (p<0.02), VEGF-D (p<0.01), placental growth factor (p<0.01), amphiregulin (p<0.02), hepatocyte growth factor (p<0.01) and transforming growth factor-α (p<0.05) and decreased VEGF receptor-2 (p<0.04) and epidermal growth factor receptor (p<0.01) levels compared with controls.

Conclusion

Plasma RET differentiates patients with PAH from those with CTEPH, systolic or diastolic heart failure with or without pulmonary hypertension as well as healthy controls. Future studies would be of value to determine the clinical usefulness of RET as a biomarker and its link to PAH pathophysiology.

Receptor tyrosine kinases have been shown to promote PAH remodelling. Plasma RET differentiates PAH from other causes of PH. RET could have the potential to be used as a future diagnostic biomarker.http://bit.ly/2LChPUS

The Role of Noninvasive Endpoints in Predicting Long-Term Outcomes in Pulmonary Arterial Hypertension

Background

Until recently, many clinical trials in patients with pulmonary arterial hypertension (PAH) evaluated exercise capacity with 6-minute walk distance (6MWD) as the primary endpoint. Common secondary endpoints include PAH functional class (FC), which assesses symptoms, and either brain natriuretic peptide (BNP) or the inactive N-terminal cleavage product of its prohormone (NT-proBNP), which assesses cardiac function.

Objective

Examine the relationships among 6MWD, FC, and BNP/NT-proBNP measured at baseline or follow-up with long-term outcomes in PAH studies.

Methods

Relevant literature from January 1990 to April 2018 were obtained by searching PubMed, Embase, and Cochrane. Articles in English reporting on associations between 6MWD, FC, or BNP/NT-proBNP and outcomes in PAH were identified. Each endpoint was evaluated individually. Prespecified inclusion and exclusion criteria were applied at level 1 (titles/abstracts) and level 2 (full-text review).

Results

The database search yielded 836 unique records; 65 full-text articles were reviewed. Twenty-five studies were eligible for inclusion. Findings supported the importance of measuring PAH noninvasive endpoints in predicting long-term outcomes. Patients with shorter or decreased 6MWD, poor (III/IV) or declining FC (e.g., from II to III), or elevated or increasing BNP/NT-proBNP had a higher risk of death and costly events (e.g., hospitalization, lung transplant). FC also predicted health care resource utilization and costs. Collectively, these endpoints establish risk groups that predict likelihood of complications from PAH or death.

Conclusion

Assessment of 6MWD, FC, and BNP/NT-proBNP provides low-cost, efficient, and noninvasive means of predicting long-term health and economic outcomes in patients with PAH.

Pulmonary Arterial Hypertension-Related Morbidity Is Prognostic for Mortality

BACKGROUND

Registry data suggest that disease progression in pulmonary arterial hypertension (PAH) is indicative of poor prognosis. However, the prognostic relevance of PAH-related morbidity has not been formally evaluated in randomized controlled trials.

OBJECTIVES

The purpose of these analyses was to assess the impact of morbidity events on the risk of subsequent mortality using the landmark method and data from the SERAPHIN and GRIPHON studies.

METHODS

For each study, the risk of all-cause death up to the end of the study was assessed from the landmark time point (months 3, 6, and 12) according to whether a patient had experienced a primary endpoint morbidity event before the landmark. Each analysis was conducted using data from all patients who were available for survival follow-up at the landmark.

RESULTS

In the SERAPHIN study, on the basis of the 3-month landmark time point, patients who experienced a morbidity event before month 3 had an increased risk of death compared with patients who did not (hazard ratio [HR]: 3.39; 95% confidence interval [CI]: 1.94 to 5.92). In the GRIPHON study, on the basis of the 3-month landmark time point, there was also an increased risk with a HR of 4.48; (95% CI: 2.98 to 6.73). Analyses based on 6-month and 12-month landmarks also showed increased risk in patients who experienced morbidity events, albeit with a reduced HR.

CONCLUSIONS

These results demonstrate the prognostic relevance of PAH-related morbidity as defined in the SERAPHIN and GRIPHON studies, highlighting the importance of preventing disease progression in patients with PAH and supporting the clinical relevance of SERAPHIN and GRIPHON morbidity events. (Study of Macitentan [ACT-064992] on Morbidity and Mortality in Patients With Symptomatic Pulmonary Arterial Hypertension [SERAPHIN]; NCT00660179; Selexipag [ACT-293987] in Pulmonary Arterial Hypertension [GRIPHON]; NCT01106014).

Mesenchymal stem/stromal cell therapy for pulmonary arterial hypertension: Comprehensive review of preclinical studies

Pulmonary arterial hypertension (PAH) is a disease characterized by progressive pulmonary vascular remodeling, resulting in right-sided heart failure and premature death. Current available therapies for PAH have limited efficacy, and new therapeutic strategies need to be developed. Mesenchymal stem/stromal cells (MSCs) may offer a novel therapeutic approach to PAH. Since the first report in 2006, a number of preclinical studies have demonstrated a potential therapeutic effect of this approach, with attenuated hemodynamic and histological progression of PAH, in animal models of PAH. However, there remain several issues that should be addressed for this approach to be clinically successful. With the aim to highlight such issues, this review clarifies existing knowledge on MSC therapy for PAH in preclinical studies, including types of PAH animal models used for MSC therapy, MSC sources, and administration protocol (route, cell dose, and timing of administration). This review thereafter summarizes thoroughly and discusses the mechanism underpinning MSC therapy for PAH. For clinical success of MSC therapy, insufficient evidence of safety (e.g. critical risk of pulmonary embolism) and therapeutic efficacy of MSCs on established PAH with severe vascular remodeling, as well as further optimization of the MSC administration protocol, are considered as remaining issues to be addressed. In terms of the efficacy, it is controversial whether angiogenic cytokines, which are considered as one of the therapeutic mechanisms of MSC, have beneficial effect for human PAH. To address these issues, further preclinical data using more clinically-relevant animal models of PAH, such as SU5416 model, should be accumulated, whereas most preclinical studies have been conducted using monocrotaline-induced PAH model. While MSC therapy has a great potential to become a novel therapy in PAH, continuing careful preclinical research is warranted for clinical success in PAH.

The importance of patient perspectives in pulmonary hypertension

The assessment of objective measurement of cardiopulmonary status has helped us achieve better clinical outcomes for patients and develop new therapies through to the point of market access; however, patient surveys indicate that more can be done to improve holistic care and patient engagement. In this multidisciplinary review, we examine how clinical teams can acknowledge and embrace the individual patient's perspective, and thus improve the care for individual patients suffering from pulmonary hypertension by cultivating the importance and relevance of health-related quality of life in direct clinical care. At the individual level, patients should be provided with access to accredited specialist centres which provide a multidisciplinary approach where there is a culture focused on narrative medicine, quality of life, shared decision making and timely access to palliative care, and where there is participation in education. On a larger scale, we call for the development, expansion and promotion of patient associations to support patients and carers, lobby for access to best care and treatments, and provide input into the development of clinical trials and registries, focusing on the patients’ perspective.

Analysis and discussion on the importance of patients' perspectives in pulmonary hypertensionhttp://ow.ly/edOt30mgYoI

Clinical trial design and new therapies for pulmonary arterial hypertension

Until 20 years ago the treatment of pulmonary arterial hypertension (PAH) was based on case reports and small series, and was largely ineffectual. As a deeper understanding of the pathogenesis and pathophysiology of PAH evolved over the subsequent two decades, coupled with epidemiological studies defining the clinical and demographic characteristics of the condition, a renewed interest in treatment development emerged through collaborations between international experts, industry and regulatory agencies. These efforts led to the performance of robust, high-quality clinical trials of novel therapies that targeted putative pathogenic pathways, leading to the approval of more than 10 novel therapies that have beneficially impacted both the quality and duration of life. However, our understanding of PAH remains incomplete and there is no cure. Accordingly, efforts are now focused on identifying novel pathogenic pathways that may be targeted, and applying more rigorous clinical trial designs to better define the efficacy of these new potential treatments and their role in the management scheme. This article, prepared by a Task Force comprised of expert clinicians, trialists and regulators, summarises the current state of the art, and provides insight into the opportunities and challenges for identifying and assessing the efficacy and safety of new treatments for this challenging condition.

State of the art and research perspectives in clinical trial design and new therapies for pulmonary arterial hypertensionhttp://ow.ly/VHQ030mfRxc

Riociguat improves health-related quality of life for patients with pulmonary arterial hypertension: results from the phase 4 MOTION study

Pulmonary arterial hypertension (PAH) is characterized by progressive dyspnea and exercise limitation and is associated with reduced health-related quality of life. Few clinical studies have evaluated the primary effects of treatment of PAH from the patient perspective. Here, we present the impact of riociguat on patient-reported outcomes (PROs) in treatment-naïve patients with PAH. MOTION (NCT02191137) was an open-label, phase 4 trial of riociguat monotherapy in treatment-naïve patients with PAH. The primary endpoint was the change in total score from baseline to Week 24 in the Living with Pulmonary Hypertension (LPH) questionnaire. The Short Form-12 Health Survey and Work Limitations Questionnaire 8 were also utilized to assess PROs. Other secondary endpoints included change from baseline in World Health Organization functional class (WHO FC), 6-min walk distance (6MWD), Modified Borg Dyspnea Scale, and safety. At week 24 (n = 66), the mean (standard deviation [SD]) total LPH score was 37.17 (24.61), for a mean (SD) change from baseline of -10.99 (22.51). At last visit, with week 24 imputed, the mean (SD) total score was 40.63 (28.38), for a mean (SD) change from baseline of -5.40 (27.8) (n = 75; P = 0.0484). Improvement in LPH questionnaire total score was observed by week 4 and was maintained through week 24. Improvements were observed in WHO FC, Modified Borg Dyspnea Scale, and accelerometer-measured 6MWD at week 24. Treatment with riociguat had a positive impact on PROs in treatment-naïve patients with PAH and was well tolerated, with a similar safety profile to that observed in placebo-controlled phase 3 trials.

Myeloid angiogenic cells exhibit impaired migration, reduced expression of endothelial markers, and increased apoptosis in idiopathic pulmonary arterial hypertension 1

Idiopathic pulmonary arterial hypertension (IPAH) is a rare and devastating condition. There is no known cure for IPAH, and current treatment options are not always effective. Autologous myeloid angiogenic cells (MACs) have been explored as a novel therapy for IPAH, but preliminary data from clinical trials show limited beneficial effects. A complete understanding of IPAH MAC function remains elusive. This study was designed to comprehensively compare cell function between IPAH MACs and healthy control MACs. MACs were procured through the culture of peripheral blood mononuclear cells in endothelial selective medium for 7 days. Compared with healthy MACs, IPAH MACs exhibited (1) significantly lower levels of endothelial markers as shown by fluorescence microscopy; (2) a markedly higher rate of apoptosis under both normal culture condition and serum starvation as shown by the TUNEL assay; (3) significantly decreased migration towards vascular endothelial growth factor as shown by a modified Boyden chamber migration assay; and (4) similar vascular endothelial growth factor and endothelial nitric oxide synthase mRNA levels as shown by reverse transcription quantitative PCR. In conclusion, various aspects of IPAH MAC function are impaired. To achieve greater therapeutic benefits, pharmacologic and (or) genetic manipulations to improve IPAH MAC function, particularly to promote cell survival and migration, are warranted.

Pulmonary Hypertension: The Role of Lung Transplantation

Despite advances in targeted medical therapy, pulmonary arterial hypertension (PAH) remains a fatal disease because of progressive right ventricular dysfunction. For patients who are refractory to medical therapy, heart-lung and lung transplantation are important treatment options. Because of longer waiting time, surgical interventions including extracorporeal lung support and atrial septostomy can be used in PAH patients bridging to transplantation.

Exercise Training and Rehabilitation in Pulmonary Hypertension

Within the last years, exercise training and rehabilitation as add-on to medical treatment has become an emerging field in pulmonary hypertension. Owing to the beneficial effects of exercise training in pulmonary hypertension, the new European Respiratory Society/European Society of Cardiology guidelines for pulmonary hypertension recommended a supervised and closely monitored exercise and respiratory training/rehabilitation as add-on to medical therapy (class IIa, level of evidence B). In this article, different training modalities, effects of exercise training, possible pathobiological mechanisms of action, and future research questions are discussed.

Berberine attenuates pulmonary arterial hypertension via protein phosphatase 2A signaling pathway both in vivo and in vitro

Excessive proliferation, migration, and antiapoptosis of pulmonary artery (PA) smooth muscle cells (PASMCs) underlies the development of pulmonary vascular remodeling. The innervation of the PA is predominantly sympathetic, and increased levels of circulating catecholamines have been detected in pulmonary arterial hypertension (PAH), suggesting that neurotransmitters released by sympathetic overactivation may play an essential role in PAH. However, the responsible mechanism remains unclear. Here, to investigate the effects of norepinephrine (NE) on PASMCs and the related mechanism, we used 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, the proliferating cell nuclear antigen and the cell counting kit-8 assay to evaluate the proliferation of PASMCs, Boyden chamber migration, and wound-healing assays to assess migration and western blot analysis to investigate protein expression. We demonstrated that the phosphorylation level of the protein phosphatase 2A (PP2A) catalytic subunit (Y307) was higher in PAH patients and PAH models than in controls, both in vivo and in vitro. In addition, NE induced the proliferation and migration of PASMCs, which was attenuated by berberine (BBR), a Chinese herbal medicine, and/or PP2A overexpression. PP2A inhibition worsened NE-induced PAH and could not be reversed by BBR. Thus, PP2A is critical in driving PAH, and BBR may alleviate PAH via PP2A signaling pathways, thereby offering a potential therapeutic option for PAH.

Anti-platelet drugs and their necessary interaction with endothelial mediators and platelet cyclic nucleotides for therapeutic efficacy

For many millions of patients at secondary risk of coronary thrombosis pharmaceutical protection is supplied by dual anti-platelet therapy. Despite substantial therapeutic developments over the last decade recurrent thrombotic events occur, highlighting the need for further optimisation of therapies. Importantly, but often ignored, anti-platelet drugs interact with cyclic nucleotide systems in platelets and these are the same systems that mediate key endogenous pathways of platelet regulation, notably those dependent upon the vascular endothelium. The aim of this review is to highlight interactions between the anti-platelet drugs, aspirin and P2Y₁₂ receptor antagonists and endogenous pathways of platelet regulation at the level of cyclic nucleotides. These considerations are key to concepts such as anti-platelet drug resistance and individualized anti-platelet therapy which cannot be understood by study of platelets in isolation from the circulatory environment. We also explore novel and emerging therapies that focus on preserving haemostasis and how the concepts outlined in this review could be exploited therapeutically to improve anti-thrombotic efficacy whilst reducing bleeding risk.

Methods for the analysis of multiple endpoints in small populations: A review

While current guidelines generally recommend single endpoints for primary analyses of confirmatory clinical trials, it is recognized that certain settings require inference on multiple endpoints for comprehensive conclusions on treatment effects. Furthermore, combining treatment effect estimates from several outcome measures can increase the statistical power of tests. Such an efficient use of resources is of special relevance for trials in small populations. This paper reviews approaches based on a combination of test statistics or measurements across endpoints as well as multiple testing procedures that allow for confirmatory conclusions on individual endpoints. We especially focus on feasibility in trials with small sample sizes and do not solely rely on asymptotic considerations. A systematic literature search in the Scopus database, supplemented by a manual search, was performed to identify research papers on analysis methods for multiple endpoints with relevance to small populations. The identified methods were grouped into approaches that combine endpoints into a single measure to increase the power of statistical tests and methods to investigate differential treatment effects in several individual endpoints by multiple testing.

MiR-339 inhibits proliferation of pulmonary artery smooth muscle cell by targeting FGF signaling

Pulmonary artery hypertension (PAH) is a fatal disorder. Recent studies suggest that microRNA (miRNA) plays an important role in regulating proliferation of pulmonary artery smooth muscle cells (PASMC), which underlies the pathology of PAH. However, the exact mechanism of action of miRNAs remains elusive. In this study, we found that miR‐339 was highly expressed in the cardiovascular system and was downregulated by a group of cytokines and growth factors, especially PDGF‐BB and FGF2. Functional analyses revealed that miR‐339 can inhibit proliferation of PASMC. Also, miR‐339 inhibited FGF2‐induced proliferation, but had no effect on proliferation induced by PDGF‐BB. The fibroblast growth factor receptor substrate 2 (FRS2) was identified as a potential direct target of miR‐339. Consistent with the actions of miR‐339, knockdown of FRS2 only inhibited FGF2‐ but not PDGF‐BB‐induced proliferation of PASMC. In addition, our results showed that inhibition of ERK and PI3K abrogated the downregulation of miR‐339 induced by PDGF‐BB. Finally, miR‐339 expression was found to be decreased in the pulmonary arteries of rats with MCT‐induced PAH. Our study is the first report on the biological role of miR‐339 in regulating proliferation of PASMC by targeting FGF signaling, providing new mechanistic insights into PASMC proliferation and pathogenesis of PAH.

Inhaled Fasudil Lacks Pulmonary Selectivity in Thromboxane-Induced Acute Pulmonary Hypertension in Newborn Lambs

INTRODUCTION

Pulmonary hypertension (PH) is a potentially deadly disease for infants and adults with few existing medical interventions and no cure. In PH, increased blood pressure in the pulmonary artery eventually leads to heart failure. Fasudil, an antagonist of Rho-kinase, causes vasodilation leading to decreased systemic artery pressure and pulmonary artery pressure (PAP). This study compared the effects of fasudil administered as either an intravenous infusion or inhaled aerosol in newborn lambs.

HYPOTHESIS

Inhaled aerosol delivery of fasudil will provide selective pulmonary vasodilation when compared with intravenous administration.

METHODS

Newborn lambs (∼11 days) were surgically instrumented and mechanically ventilated under anesthesia. A pulmonary artery catheter and ultrasonic flow probe were inserted to measure hemodynamics. Acute PH was pharmaceutically induced via continuous intravenous infusion of thromboxane. After achieving a 2- to 3-fold elevation of PAP, fasudil was administered either as intravenous infusion (2.5 mg/kg) or inhaled aerosol (100 mg of fasudil in 2 mL of saline). Changes in PAP, mean systemic arterial pressure (MABP), pulmonary vascular resistance (PVR), systemic vascular resistance (SVR), cardiac output, and heart rate were assessed. In addition, plasma concentrations of fasudil were measured.

RESULTS

Both routes of fasudil delivery produced significant decreases in PAP and PVR but also produced similar decreases in MABP and SVR. The C_max for intravenous fasudil was greater than that for inhaled fasudil.

CONCLUSIONS

These results suggest inhaled fasudil lacks pulmonary selectivity when compared with intravenous fasudil.

Psychometric Validation of the Pulmonary Arterial Hypertension-Symptoms and Impact (PAH-SYMPACT) Questionnaire: Results of the SYMPHONY Trial

BACKGROUND

Disease-specific patient-reported outcome (PRO) instruments are important in assessing the impact of disease and treatment. The Pulmonary Arterial Hypertension-Symptoms and Impact Questionnaire is the first instrument for quantifying pulmonary arterial hypertension (PAH) symptoms and impacts developed according to the 2009 US Food and Drug Administration PRO guidance; previous qualitative research in patients with PAH supported its initial content validity.

METHODS

Content finalization and psychometric validation were conducted by using data from A Study of Macitentan in Pulmonary Arterial Hypertension to Validate the PAH-SYMPACT (SYMPHONY), a single-arm, 16-week trial with macitentan 10 mg in US patients with PAH. Item performance, Rasch analysis, and factor analyses were used to select the final item content of the PRO and to define its domain structure. Internal consistency, test-retest reliability, known-group and construct validity, sensitivity to change, and influence of oxygen on item performance were evaluated.

RESULTS

Data from 278 patients (79% female; mean age: 60 years) were analyzed. Following removal of redundant/misfitting items, the final questionnaire has 11 symptom items across two domains (cardiopulmonary and cardiovascular symptoms) and 11 impact items across two domains (physical and cognitive/emotional impacts). Differential item function analysis confirmed that PRO scoring is unaffected by oxygen use. For all four domains, internal consistency reliability was high (Cronbach's alpha > 0.80), and scores were highly reproducible in stable patients (intraclass correlation coefficient: 0.84-0.94). Correlations with the Cambridge Pulmonary Hypertension Outcome Review questionnaire and the 36-item Medical Outcomes Study Short Form Survey were moderate to high ([r] = 0.34-0.80). The questionnaire differentiated well between patients with varying disease severity levels and was sensitive to improvements in clinician- and patient-reported disease severity.

CONCLUSIONS

The Pulmonary Arterial Hypertension-Symptoms and Impact Questionnaire is a brief, disease-specific PRO instrument possessing good psychometric properties that can be administered in clinical practice and clinical studies.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01841762; URL: www.clinicaltrials.gov.

Right atrium enlargement predicts clinically significant supraventricular arrhythmia in patients with pulmonary arterial hypertension

BACKGROUND

Right atrial (RA) enlargement is a common finding in patients with pulmonary arterial hypertension (PAH) and an important predictor of mortality, however its relation to the risk of atrial arrhythmias has not been assessed.

OBJECTIVES

To assess whether RA enlargement is associated with supraventricular arrhythmias (SVA) and whether it predicts new clinically significant SVA (csSVA).

METHODS

Patients with PAH were recruited between January 2010 and December 2014 and followed until January 2017. csSVA was diagnosed if it resulted in hospitalization. To assess predictors of new csSVA, only patients without a history of SVA at baseline were analyzed.

RESULTS

Among 97 patients, any SVA was observed in 45 (46.4%) and included permanent atrial fibrillation(AF, n = 8), paroxysmal AF (n = 10), permanent atrial flutter (AFl, n = 1), paroxysmal AFl (n = 2) or other types of supraventricular tachycardia (n = 24). Patients with SVA as compared to patients without SVA were characterized by older age, lower distance in a 6-minute test, higher NT-proBNP, higher RA area index (RAai), left atrial area index, mean right atrial pressure (mRAP) and were more commonly treated with β-blocker. Eighty five patients who were in sinus rhythm at baseline assessment and had no history of significant SVA were observed for 37 ± 19.9 months. During that time csSVA occurred in 15.3%. In univariate models, the occurrence of csSVA were predicted by age, right ventricular ejection fraction, right ventricular end diastolic index, RAai and mRAP, but in multivariate model only RAai remained significant predictor for csSVA (HR of 1.23, 95%CI: 1.11-1.36, p < 0.001). The optimal threshold for RA enlargement as discriminator of csSVA was 21.7 cm2/m2.

CONCLUSIONS

In PAH patients RA enlargement is associated with increased prevalence of SVA. RAai is an independent predictor of hospitalization due to csSVA.

Right ventricular fibrosis and dysfunction: Actual concepts and common misconceptions

Fibrosis and remodeling of the right ventricle (RV) are associated with RV dysfunction and mortality of patients with pulmonary hypertension (PH) but it is unknown how much RV fibrosis contributes to RV dysfunction and mortality. RV fibrosis manifests as fibroblast accumulation and collagen deposition which may be excessive. Although extracellular matrix deposition leads to elevated ventricular stiffness, it is not known to which extent it affects RV function. Various animal models of pulmonary hypertension have been established to investigate the role of fibrosis in RV dysfunction and failure. However, they do not perfectly resemble the human disease. In the current review we describe the major characteristics of RV fibrosis, molecular mechanisms regulating the fibrotic process, and discuss how therapeutic targeting of fibrosis might affect RV function.

MR and CT Imaging for the Evaluation of Pulmonary Hypertension

Imaging plays a central role in the diagnosis and management of all forms of pulmonary hypertension (PH). Although Doppler echocardiography is essential for the evaluation of PH, its ability to optimally evaluate the right ventricle and pulmonary vasculature is limited by its 2-dimensional planar capabilities. Magnetic resonance and computed tomography are capable of determining the etiology and pathophysiology of PH, and can be very useful in the management of these patients. Exciting new techniques such as right ventricle tissue characterization with T1 mapping, 4-dimensional flow of the right ventricle and pulmonary arteries, and computed tomography lung perfusion imaging are paving the way for a new era of imaging in PH. These imaging modalities complement echocardiography and invasive hemodynamic testing and may be useful as surrogate endpoints for early phase PH clinical trials. Here we discuss the role of magnetic resonance imaging and computed tomography in the diagnosis and management of PH, including current uses and novel research applications, and we discuss the role of value-based imaging in PH.

A study of clinical and physiological relations of daily physical activity in precapillary pulmonary hypertension

Daily physical activity is reduced in precapillary pulmonary hypertension (PH), but the underlying mechanisms are inadequately explored. We sought to investigate clinical and physiological relations of daily physical activity and profile differences between less and more active patients with precapillary PH. A prospective, cross-sectional study of 20 patients with precapillary PH who undertook 1) a comprehensive clinical assessment, 2) a preliminary treadmill test, 3) 7-day monitoring of daily walking intensity with triaxial accelerometry, and 4) a personalized treadmill test corresponding to the individual patient mean daily walking intensity with real-time physiological measurements. Significant clinical correlations with individual patient mean walking intensity [1.71 ± 0.27 (SD) m/s²] were observed for log-transformed N-terminal probrain natriuretic peptide (log NT-proBNP; r = -0.75, P = <.001), age (r = -0.70, P = 0.001), transfer factor for carbon monoxide %predicted (r = 0.51, P = 0.022), and 6-min walk distance (r = 0.50, P = 0.026). Significant physiological correlations were obtained for heart rate reserve (r = 0.68, P = 0.001), quadriceps tissue oxygenation index (Q-[Formula: see text]; r = 0.58, P = 0.008), change in Q-[Formula: see text] from rest (r = 0.60, P = 0.006), and ventilatory equivalent for oxygen uptake (r = -0.56, P = 0.013). Stepwise multiple regression analyses retained log NT-proBNP (R² = 0.55), heart rate reserve (R² = 0.44), and Q-[Formula: see text] (R² = 0.13) accounting for a significant variance in individual walking intensity. Less active patients had greater physical activity-induced cardiopulmonary impairment, worse quadriceps oxygenation profile, and compromised health-related quality of life compared with more active patients. These preliminary findings suggest a significant relation between right ventricular and peripheral muscle oxygenation status and reduced daily physical activity in precapillary PH. Further research is warranted to unravel the physiological determinants, establish clinical predictors, and identify beneficial interventions.NEW & NOTEWORTHY Daily physical activity holds promise to be a meaningful, patient-related outcome measure in pulmonary hypertension. In this study, novel findings in a representative sample of patients with precapillary pulmonary hypertension link reduced daily walking activity, as measured by triaxial accelerometry, with compromised right ventricular and pulmonary vascular status, peripheral muscle oxygenation, and health-related quality of life, providing a preliminary insight into the physiological mechanisms and clinical predictors of daily physical activity in precapillary pulmonary hypertension.

Corneal Endothelial Cell Integrity in Precut Human Donor Corneas Enhanced by Autocrine Vasoactive Intestinal Peptide

PURPOSE

To demonstrate that vasoactive intestinal peptide (VIP), a corneal endothelial (CE) cell autocrine factor, maintains the integrity of corneal endothelium in human donor corneoscleral explants precut for endothelial keratoplasty.

METHODS

Twelve paired human donor corneoscleral explants used as control versus VIP-treated explants (10 nM, 30 minutes, 37°C) were shipped (4°C) to the Lions Eye Institute for Transplantation and Research for precutting (Moria CBM-ALTK Keratome), shipped back to the laboratory, and cultured in ciliary neurotrophic factor (CNTF, 0.83 nM, 37°C, 24 hours). Trephined endothelial discs (8-8.5 mm) were analyzed for differentiation markers (N-cadherin, CNTF receptor α subunit [CNTFRα], and connexin 43) by Western blot after a quarter of the discs from 4 paired explants were cut away and stained with alizarin red S for microscopic damage analysis. Two additional paired explants (6 days in culture) were stained for panoramic view of central CE damage.

RESULTS

VIP treatment increased N-cadherin and CNTFRα levels (mean ± SEM) to 1.38 ± 0.11-fold (P = 0.003) and 1.46 ± 0.22-fold (P = 0.03) of paired controls, respectively, whereas CE cell CNTF responsiveness in upregulation of connexin 43 increased to 2.02 ± 0.5 (mean ± SEM)-fold of the controls (P = 0.04). CE damage decreased from (mean ± SEM) 10.0% ± 1.2% to 1.6% ± 0.3% (P < 0.0001) and 9.1% ± 1.1% to 2.4% ± 1.0% (P = 0.0006). After 6 days in culture, the damage in whole CE discs decreased from 20.0% (control) to 5.5% (VIP treated).

CONCLUSIONS

VIP treatment before precut enhanced the preservation of corneal endothelium.

Physical Activity in Pediatric Pulmonary Arterial Hypertension Measured by Accelerometry. A Candidate Clinical Endpoint

RATIONALE

The development of evidence-based treatment guidelines for pediatric pulmonary arterial hypertension (PAH) is hampered by lack of pediatric clinical trials. Trial design is hampered by lack of a feasible clinical endpoint in this population.

OBJECTIVES

To evaluate the use of accelerometry for measuring physical activity (PA) in pediatric PAH and to investigate its correlation with clinical disease severity markers.

METHODS

We included children from the Dutch National Network for Pediatric Pulmonary Hypertension. Control patients were recruited from the outpatient cardiology clinic of the Beatrix Children's Hospital. Children were asked to wear the accelerometer for 7 days. Vector magnitude counts per minute (VM CPM) and time per day spent in different PA intensity levels were defined as accelerometer outcomes.

MEASUREMENTS AND MAIN RESULTS

VM CPM was lower in children with PAH (n = 29) than in controls (n = 60; 647 vs. 921; P < 0.001). Children with PAH spent less time in moderate and vigorous PA (13 vs. 29 min/d and 2 vs. 13 min/d, respectively; P < 0.001). Time spent in moderate and vigorous PA correlated inversely with World Health Organization functional class. Time spent in moderate PA correlated positively with 6-minute-walk distance. In post hoc analyses, VM CPM and time spent in moderate/vigorous combined and vigorous PA were associated with outcome (P ≤ 0.044).

CONCLUSIONS

PA is markedly decreased in children with PAH. Accelerometer output correlated with clinical disease severity markers and may predict outcome. We showed an exciting potential of PA as a meaningful endpoint for clinical trials in pediatric PAH, although its clinical utility and prognostic value need to be further validated.

Decreased pulmonary arterial proportional pulse pressure is associated with increased mortality in group 1 pulmonary hypertension

BACKGROUND

This study evaluated the utility of a novel index, pulmonary arterial (PA) proportional pulse pressure (PAPP; range 0-1, defined as [PA systolic pressure - PA diastolic pressure] / PA systolic pressure), in predicting mortality in patients with World Health Organization group 1 pulmonary hypertension (PH).

HYPOTHESIS

Low PAPP is associated with increased 5-year mortality independent of a validated contemporary risk-prediction equation (Pulmonary Hypertension Connection [PHC] equation).

METHODS

In a group of 262 patients in the National Institutes of Health Primary Pulmonary Hypertension (NIH-PPH) Registry, PAPP and the PHC risk equation were used to predict mortality during 5 years of follow-up using Cox proportional hazards models. Kaplan-Meier survival curves were used to compare mortality among PAPP quartiles, and significance was tested using the log-rank test.

RESULTS

Patients in the lowest quartile (PAPP ≤0.47) had a significantly higher 5-year mortality than did patients in higher quartiles (log-rank P = 0.016). In a Cox model adjusted for the PHC equation, PAPP remained significantly associated with 5-year mortality (hazard ratio: 0.74 per 0.10 increase in PAPP, 95% confidence interval: 0.61-0.90). The χ² statistic for the single PAPP covariate in this model was 8.8 (P = 0.003), which compared favorably with the χ² statistic of 15.2 (P < 0.0001) for the multivariable PHC equation.

CONCLUSIONS

PAPP, an index of ventricular-arterial coupling, is independently associated with survival in World Health Organization group 1 PH. The use of this easily measurable index for guiding risk stratification needs further investigation.

Pediatric Development of Bosentan Facilitated by Modeling and Simulation

BACKGROUND

Bosentan is approved for use in adult patients with pulmonary arterial hypertension. The primary aim of the pharmacokinetic modeling was the provision of a systematic guidance for study design and enhanced understanding of pharmacokinetics across the entire pediatric age range.

METHODS

A physiologically based pharmacokinetic model was developed for the pediatric population; starting from an adult model, the effects of body weight, age, and maturation of relevant metabolizing enzymes were incorporated to extrapolate the pharmacokinetics to children. A pediatric population pharmacokinetic model was developed to identify relevant covariates.

RESULTS

Based on model predictions, a dose of 0.5 mg/kg led to an exposure distinguishable from a dose of 2 mg/kg, and an additional blood sampling time point at 2 h (the predicted time of maximum concentration) allowed more precise estimation of bosentan exposure in children. The lower exposure observed in children compared with adults could be explained by maturation-related changes in clearance. Clinical data confirmed the model predictions.

CONCLUSIONS

Maturational changes in drug clearance and developmental changes in body weight were identified as key elements of bosentan pharmacokinetics in pediatric patients. Estimating bosentan exposure using physiologically based and population pharmacokinetic modeling and simulation supported dose selection in pediatric patients. Model-based exposure estimates helped in reducing the number of the youngest pediatric patients to be studied. Pharmacokinetic models can provide a systematic guidance for study design and enhanced understanding of pharmacokinetics across the entire pediatric age range.

Sorafenib as a potential strategy for refractory pulmonary arterial hypertension

Sorafenib is an inhibitor of multi-kinases including tyrosine and serine/threonine kinases. We investigated the efficacy and safety of sorafenib for the treatment of patients with refractory pulmonary arterial hypertension (PAH). Sorafenib was started in 9 patients (7 with idiopathic PAH, 2 with pulmonary veno-occlusive disease) who had severe PAH and right heart failure, in spite of treatment with vasodilators specific for PAH. Sorafenib was started as an add-on therapy at a dose of 50 or 100 mg/day, and increased to 100-400 mg/day. New York Heart Association functional class improved in 8 patients and did not change in 1. Mean pulmonary arterial pressure improved in 6 patients (14-28% decrease) and did not apparently change in 2 (follow-up catheterization was not performed in 1 patient). The main adverse effects of sorafenib were skin reactions on the hands and feet, which appeared in 5 patients. They were tolerable in 4 patients, but discontinuation of sorafenib was needed in only 1 patient. In conclusion, sorafenib had favorable effects to improve symptoms and objective variables in patients with refractory PAH, with tolerable adverse events. Sorafenib is an alternative strategy for patients with refractory PAH.

Characteristics of pediatric pulmonary hypertension trials registered on ClinicalTrials.gov

The investigation of pediatric pulmonary hypertension (PH) drugs has been identified as a high priority by the United States National Institutes of Health (NIH). Studying pediatric PH is challenging due to the rare and heterogeneous nature of the disease. We sought to define the pediatric PH clinical trials landscape, to evaluate areas of trial success or failure, and to identify potential obstacles to the study of pediatric PH drugs. Interventional pediatric (ages 0–17 years) PH trials registered on ClinicalTrials.gov from June 2005 through December 2014 were analyzed. There were 45 pediatric PH trials registered during the study period. Median (IQR) projected trial enrollment was 40 (24–63), with seven trials (16%) targeting > 100 participants. Industry was the most common trial sponsor (n = 23, 50%), with only two (4.4%) NIH-sponsored trials. Phosphodiesterase inhibitors were the most frequently studied drug (n = 18, 39%). Single group study designs were used in 44% (n = 20) with an active comparator (parallel, factorial, or cross-over designs) in 25 trials, including 22 with randomization and ten that were double-blinded. Study outcomes varied markedly with inconsistent use of known surrogate and composite endpoints. One-third of trials (n = 15, 33%) were terminated, predominantly due to poor participant enrollment. Of the 17 completed trials, 11 had published results and only three efficacy trials met their primary endpoint. There are unique challenges to drug development in pediatric PH, including enrolling patients, identifying appropriate study endpoints, and conducting randomized, controlled, double-blind trials where the likelihood of meeting the study endpoint is optimized.