Prostanoid therapies in the management of pulmonary arterial hypertension

Non-traumatic Acute Subdural Hematoma in a Patient With Scleroderma Complicated by Pulmonary Arterial Hypertension: A Case Report

Non-traumatic acute subdural hematoma (SDH) in patients with scleroderma is infrequently described in literature reviewing the neurologic disorders in scleroderma. We report a case of a patient with scleroderma complicated by severe pulmonary arterial hypertension (PAH), and a history of pulmonary embolism on warfarin who developed an SDH, requiring hemicraniectomy after initiating therapy with IV epoprostenol. The proposed mechanisms for SDH development and management strategy are discussed.

Incidence of Bloodstream Infection in Patients with Pulmonary Hypertension under Intravenous Epoprostenol or Iloprost—A Multicentre, Retrospective Study

Intravenous synthetic prostacyclin analogs (iPCAs), such as epoprostenol, treprostinil and iloprost have been widely used for the treatment of pulmonary arterial hypertension (PAH). Despite having good outcomes, continuous infusion of iPCAs has been associated with some adverse effects. Bloodstream infection (BSI) is one of the most severe complications, although poorly recognized, especially under iloprost administration, which few studies have addressed. This study aimed to compare the BSI incidence rates between intravenous iloprost and epoprostenol administration. Patients with pulmonary hypertension (PH) functional class III or IV receiving intravenous iloprost or epoprostenol through Hickman catheter, between 2004 and 2019, were retrospectively selected from two PH treatment centers. From a total of 36 patients (13 for iloprost and 23 for epoprostenol), 75% (n = 27) fulfilled the PAH criteria, mainly belonging to the idiopathic group. Overall BSI rate was 1.5/1000 days of treatment (3.38 and 0.09/1000 days for iloprost and epoprostenol, respectively). Patients receiving iloprost were at a higher risk of developing BSI than those receiving epoprostenol (HR: 12.5; 95% CI: 1.569–99.092). A higher mortality rate from BSI was also identified in the iloprost group (p = 0.04). Twenty-seven patients developed BSI, with 92% of them requiring hospitalization. A total of 29 agents were found, 10 Gram-positive (mainly Staphylococcus aureus; n = 5) and 19 Gram-negative (mainly Pseudomonas aeruginosa; n = 6) bacteria. Iloprost administration was linked to a significantly higher incidence of BSI, worse prognosis, and more BSI-related deaths than epoprostenol. BSI due to Gram-negative, commensal, low-virulence bacteria was also higher in the iloprost group. In short, physicians should be aware when prescribing iPCA to guarantee their patients’ safety and best medical care.

Effect of Inhalation Profile on Delivery of Treprostinil Palmitil Inhalation Powder

Treprostinil palmitil (TP), a prodrug of treprostinil, is being developed as an inhalation powder (TPIP) for the treatment of patients with pulmonary arterial hypertension (PAH) and pulmonary hypertension due to interstitial lung disease (PH-ILD). In ongoing human clinical trials, TPIP is administered via a commercially available high resistance (HR) RS01 capsule-based dry powder inhaler (DPI) device manufactured by Berry Global (formerly Plastiape), which utilizes the patient's inspiratory flow to provide the required energy to deagglomerate and disperse the powder for delivery to their lungs. In this study, we characterized the aerosol performance of TPIP in response to changes in inhalation profiles to model more realistic use scenarios, i.e., for reduced inspiratory volumes and with inhalation acceleration rates that differ from those described in the compendia. The emitted dose of TP for all combinations of inhalation profiles and volumes ranged narrowly between 79 and 89% for the 16 and 32 mg TPIP capsules at the 60 LPM inspiratory flow rate but was reduced to 72-76% for the 16 mg TPIP capsule under the scenarios at the 30 LPM peak inspiratory flow rate. There were no meaningful differences in the fine particle dose (FPD) at all conditions at 60 LPM with the 4 L inhalation volume. The FPD values for the 16 mg TPIP capsule ranged narrowly between 60 and 65% of the loaded dose for all inhalation ramp rates with a 4 L volume and at both extremes of ramp rates for inhalation volumes down to 1 L, while the FPD values for the 32 mg TPIP capsule ranged between 53 and 65% of the loaded dose for all inhalation ramp rates with a 4 L volume and at both extremes of ramp rates for inhalation volumes down to 1 L for the 60 LPM flow rate. At the 30 LPM peak flow rate, the FPD values for the 16 mg TPIP capsule ranged narrowly between 54 and 58% of the loaded dose at both extremes of the ramp rates for inhalation volumes down to 1 L. Based on these in vitro findings, the TPIP delivery system appears not to be affected by the changes in inspiratory flow profiles or inspiratory volumes that might be expected to occur in patients with PAH or PH associated with underlying lung conditions such as ILD.

Transcription factors in the pathogenesis of pulmonary arterial hypertension-Current knowledge and therapeutic potential

Pulmonary arterial hypertension (PAH) is a disease characterized by elevated pulmonary vascular resistance and pulmonary artery pressure. Mortality remains high in severe cases despite significant advances in management and pharmacotherapy. Since currently approved PAH therapies are unable to significantly reverse pathological vessel remodeling, novel disease-modifying, targeted therapeutics are needed. Pathogenetically, PAH is characterized by vessel wall cell dysfunction with consecutive remodeling of the pulmonary vasculature and the right heart. Transcription factors (TFs) regulate the process of transcribing DNA into RNA and, in the pulmonary circulation, control the response of pulmonary vascular cells to macro- and microenvironmental stimuli. Often, TFs form complex protein interaction networks with other TFs or co-factors to allow for fine-tuning of gene expression. Therefore, identification of the underlying molecular mechanisms of TF (dys-)function is essential to develop tailored modulation strategies in PAH. This current review provides a compendium-style overview of TFs and TF complexes associated with PAH pathogenesis and highlights their potential as targets for vasculoregenerative or reverse remodeling therapies.

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.

Haemoptysis in Pulmonary Arterial Hypertension Associated with Congenital Heart Disease: Insights on Pathophysiology, Diagnosis and Management

Haemoptysis represents one of the most severe major bleeding manifestations in the clinical course of pulmonary arterial hypertension (PAH) associated with congenital heart disease (CHD). Accumulating evidence indicates that dysfunction of the pulmonary vascular bed in the setting of PAH predisposes patients to increased hemorrhagic diathesis, resulting in mild to massive and life-threatening episodes of haemoptysis. Despite major advances in PAH targeted treatment strategies, haemoptysis is still correlated with substantial morbidity and impaired quality of life, requiring a multidisciplinary approach by adult CHD experts in tertiary centres. Technological innovations in the field of diagnostic and interventional radiology enabled the application of bronchial artery embolization (BAE), a valuable tool to efficiently control haemoptysis in modern clinical practice. However, bleeding recurrences are still prevalent, implying that the optimum management of haemoptysis and its implications remain obscure. Moreover, regarding the use of oral anticoagulation in patients with haemoptysis, current guidelines do not provide a clear therapeutic strategy due to the lack of evidence. This review aims to discuss the main pathophysiological mechanisms of haemoptysis in PAH-CHD, present the clinical spectrum and the available diagnostic tools, summarize current therapeutic challenges, and propose directions for future research in this group of patients.

Safety, Tolerability, and Pharmacokinetics of Treprostinil Palmitil Inhalation Powder for Pulmonary Hypertension: A Phase 1, Randomized, Double-Blind, Single- and Multiple-Dose Study

INTRODUCTION

Treprostinil is a prostacyclin vasodilator widely used for the treatment of pulmonary arterial hypertension (PAH) and, in its inhaled form, for pulmonary hypertension associated with interstitial lung disease (PH-ILD). Treprostinil palmitil inhalation powder (TPIP) is a dry powder formulation of treprostinil palmitil (TP), an ester prodrug of treprostinil. TPIP is designed to provide sustained release of treprostinil in the lung over a prolonged period, potentially enabling a once-daily (QD) dosing regimen and significantly higher tolerated doses compared with currently available treprostinil formulations. This phase 1 study assessed the safety, tolerability, and pharmacokinetics of TP and treprostinil following single and multiple QD administrations of TPIP in healthy volunteers.

METHODS

Healthy adults (aged 18-45 years) were randomized to receive single or multiple QD inhalation doses of TPIP. Participants in the single-dose phase received TPIP 112.5, 225, 450, or 675 µg (n = 6/dose) or placebo (n = 2). Participants in the multiple-dose phase received TPIP 225 µg QD for 7 days (n = 6), 112.5 µg QD for 4 days followed by 225 µg QD for 3 days (n = 6), or placebo for 7 days (n = 4).

RESULTS

Overall, 41 of 42 participants (97.6%) completed the study. In the single-dose phase, 70.8% (n = 17/24) of TPIP-treated participants experienced a treatment-emergent adverse event (TEAE) vs 0% (n = 0/2) of placebo-treated participants; the most common TEAEs (≥ 20%) were cough (45.8%), dizziness (29.2%), and throat irritation (20.8%). In the multiple-dose phase, 83.3% (n = 10/12) of TPIP-treated participants experienced a TEAE vs 50.0% of placebo-treated participants (n = 2/4); the most common TEAEs were cough (58.3% TPIP vs 50.0% placebo), headache (50.0% vs 0%), nausea (33.3% vs 0%), chest discomfort (33.3% vs 0%), and dizziness (25.0% vs 0%). Most TEAEs were mild; only seven patients experienced a moderate TEAE, and no severe or serious TEAEs occurred. In the multiple-dose phase, participants whose doses were titrated from TPIP 112.5 µg QD to 225 µg QD experienced fewer TEAEs than those who received 225 µg QD at treatment initiation (66.7% vs 100.0%), and all TEAEs with dose titration were mild. After a single dose of TPIP, treprostinil elimination t_1/2 was 8.67-11.6 h and exposure was dose proportional, with mean (CV%) C_max 78.4-717 pg/mL (38.6-72.9%) and AUC_0-∞ 1090-5480 pg·h/mL (11.5-30.0%). At steady state (TPIP 225 µg), the mean (CV%) of C_max, C_min, and AUC_τ were 193-228 pg/mL (32.9-46.4%), 17.6-22.8 ng/mL (43.7-64.4%), and 1680-1820 pg·h/mL (28.7-36.6%), respectively. The elimination t_1/2 was 6.84-8.82 h after repeat dosing. No steady-state accumulation was observed. Plasma concentrations of TP were below the limit of quantification (100 pg/mL) at all time points measured.

CONCLUSION

TPIP was well tolerated at the doses tested, and dose titration improved tolerability. Treprostinil pharmacokinetics were linear and supportive of a QD treatment regimen. These results support further development of TPIP in patients with PAH and PH-ILD.

Prostaglandin I2 signaling licenses Treg suppressive function and prevents pathogenic reprogramming

Tregs restrain both the innate and adaptive immune systems to maintain homeostasis. Allergic airway inflammation, characterized by a Th2 response that results from a breakdown of tolerance to innocuous environmental antigens, is negatively regulated by Tregs. We previously reported that prostaglandin I2 (PGI2) promoted immune tolerance in models of allergic inflammation; however, the effect of PGI2 on Treg function was not investigated. Tregs from mice deficient in the PGI2 receptor IP (IP KO) had impaired suppressive capabilities during allergic airway inflammatory responses compared with mice in which PGI2 signaling was intact. IP KO Tregs had significantly enhanced expression of immunoglobulin-like transcript 3 (ILT3) compared with WT Tregs, which may contribute to the impairment of the IP KO Treg's ability to suppress Th2 responses. Using fate-mapping mice, we reported that PGI2 signaling prevents Treg reprogramming toward a pathogenic phenotype. PGI2 analogs promoted the differentiation of naive T cells to Tregs in both mice and humans via repression of β-catenin signaling. Finally, a missense variant in IP in humans was strongly associated with chronic obstructive asthma. Together, these data support that PGI2 signaling licenses Treg suppressive function and that PGI2 is a therapeutic target for enhancing Treg function.

Characterisation of cough evoked by inhaled treprostinil and treprostinil palmitil

Cough is induced by inhaled prostacyclin analogues including treprostinil (TRE), and, at higher doses, treprostinil palmitil (TP), a prodrug of TRE. In this report, we have investigated mechanisms involved in TRE- and TP-induced cough, using a dry powder formulation of TP (TPIP) to supplement previous data obtained with an aqueous suspension formulation of TP (TPIS).

Experiments in guinea pigs and rats investigated the prostanoid receptor subtype producing cough and whether it involved activation of sensory nerves in the airways and vasculature. Experiments involved treatment with prostanoid, tachykinin and bradykinin receptor antagonists, a cyclooxygenase inhibitor and TRE administration to the isolated larynx or intravenously.

In guinea pigs, cough with inhaled TRE (1.23 µg·kg⁻¹) was not observed with an equivalent dose of TPIP and required higher inhaled doses (12.8 and 35.8 µg·kg⁻¹) to induce cough. TRE cough was blocked with IP and tachykinin NK₁ receptor antagonists but not with EP₁, EP₂, EP₃, DP₁ or bradykinin B₂ antagonists or a cyclooxygenase inhibitor. TRE administered to the isolated larynx or intravenously in rats produced no apnoea or swallowing, whereas citric acid, capsaicin and hypertonic saline had significant effects.

The mechanisms inducing cough with inhaled TRE likely involves the activation of prostanoid IP receptors on jugular C-fibres in the tracheobronchial airways. Cough induced by inhaled dry powder and nebulised formulations of TP occurs at higher inhaled doses than TRE, presumably due to the slow, sustained release of TRE from the prodrug resulting in lower concentrations of TRE at the airway sensory nerves.

Cough induced by inhaled treprostinil and treprostinil palmitil involves the activation of prostacyclin (IP) receptors located on airway tachykinin nerveshttps://bit.ly/37sXz1I

Temporarily switching from oral to intravenous selexipag in patients with pulmonary arterial hypertension: safety, tolerability, and pharmacokinetic results from an open-label, phase III study

BACKGROUND

The oral IP receptor agonist selexipag is approved for the long-term treatment of pulmonary arterial hypertension (PAH). Treatment interruptions should be avoided due to the progressive nature of the disease. An intravenous (IV) formulation of selexipag was developed to provide a treatment option for short-term interruptions to oral selexipag. In this prospective, multicenter, open-label study, the safety, tolerability, and pharmacokinetics of temporarily switching between oral and IV selexipag were investigated (NCT03187678, ClinicalTrials.gov).

METHODS

PAH patients receiving stable oral selexipag doses were enrolled. Following three consecutive IV selexipag infusions patients resumed oral selexipag. Corresponding IV and oral doses were selected to achieve comparable exposure to the active metabolite of selexipag. Safety outcomes were monitored throughout, and pharmacokinetic samples were obtained after oral and IV administration.

RESULTS

All 20 patients completed the study. Fifteen patients had adverse events (AEs), most were mild, and none resulted in discontinuation. Headache was the most common AE throughout the study (four patients). Three serious AEs occurred in two patients with underlying comorbidities when oral dosing had resumed. There were no changes in WHO functional class for any patient and no clinically symptomatic changes in blood pressure were observed. Comparable exposure to the active metabolite of selexipag was demonstrated following corresponding oral and IV selexipag doses.

CONCLUSIONS

Temporarily switching between corresponding doses of oral and IV selexipag was well-tolerated with no unexpected safety findings and comparable exposure to the active metabolite. Treatment with IV selexipag is a feasible option to bridge temporary oral selexipag treatment interruptions.

Development and Characterization of Treprostinil Palmitil Inhalation Aerosol for the Investigational Treatment of Pulmonary Arterial Hypertension

Treprostinil palmitil (TP) is a prodrug of treprostinil (TRE), a pulmonary vasodilator that has been previously formulated for inhaled administration via a nebulizer. TP demonstrates a sustained presence in the lungs with reduced systemic exposure and prolonged inhibition of hypoxia-induced pulmonary vasoconstriction in vivo. Here, we report on re-formulation efforts to develop a more convenient solution-based metered-dose inhaler (MDI) formulation of TP, a treprostinil palmitil inhalation aerosol (TPIA) that matches the pharmacokinetic (PK) and efficacy profile of a nebulized TP formulation, treprostinil palmitil inhalation suspension (TPIS). MDI canisters were manufactured using a two-stage filling method. Aerosol performance, formulation solubility, and chemical stability assays were utilized for in vitro evaluation. For in vivo studies, TPIA formulations were delivered to rodents using an inhalation tower modified for MDI delivery. Using an iterative process involving evaluation of formulation performance in vitro (TP and excipient solubility, chemical stability, physical stability, and aerosol properties) and confirmatory testing in vivo (rat PK and efficacy, guinea pig cough), a promising formulation was identified. The optimized formulation, TPIA-W, demonstrates uniform in vitro drug delivery, a PK profile suitable for a once-daily administration, efficacy lasting at least 12 h in a hypoxic challenge model, and a significantly higher cough threshold than the parent drug treprostinil.

Pharmacokinetics and tolerability of LIQ861, a novel dry-powder formulation of treprostinil

A dry-powder inhaled formulation of treprostinil (LIQ861) produced using PRINT® technology offers a substantial advantage over current nebulized therapy. Treprostinil is a synthetic prostacyclin analogue that is currently approved for inhalation administration to patients with pulmonary arterial hypertension via nebulized Tyvaso® inhalation solution. LTI-101 was a phase 1, placebo-controlled, double-blind, randomized, single-center study that evaluated the ascending single-dose pharmacokinetics of LIQ861 in healthy subjects. Six sequential, escalating doses (25, 50, 75, 100, 125, and 150 mcg) were studied to investigate treprostinil exposure from LIQ861 inhalation. Subjects (n = 57) were randomly assigned in a 3:1 ratio to receive a single dose of either LIQ861 (n = 43) or placebo (n = 14); 56 subjects completed all protocol-defined assessments. Following single-dose administration, treprostinil exposure from LIQ861 increased proportionally across the dose range studied, and the pharmacokinetics profile of treprostinil administered as LIQ861 was similar to prior reports of inhaled treprostinil. All doses of LIQ861 were generally well-tolerated with no deaths, serious adverse events, or dose-limiting toxicities. The most frequently reported treatment-emergent adverse events related to study drug administration were coughing and throat irritation, which are common to dry-powder formulations. Treatment-related treatment-emergent adverse events were reported more frequently at higher dose levels; however, all were assessed as mild in severity. We conclude that the pharmacokinetics profile of treprostinil using a dry-powder inhaled formulation increased in proportion to dose as anticipated and was similar to earlier reports of inhaled, nebulized treprostinil (Tyvaso®). Based on these results, a phase 3 study (INSPIRE; Clinicaltrials.gov Identifier NCT03399604) evaluating the long-term safety and tolerability of LIQ861 in patients with pulmonary arterial hypertension was initiated.

Downregulation of PGI2 pathway in Pulmonary Hypertension Group-III patients

Pulmonary hypertension (PH) is a progressive and life-threating lung disorder characterized by elevated pulmonary artery pressure and vascular remodeling. PH is classified into five groups, and one of the most common and lethal forms, PH Group-III is defined as PH due to lung diseases and/or hypoxia. Due to the lack of studies in this group, PH-specific drug therapies including prostacyclin (PGI₂) analogues have not been approved or recommended for use in these patients. PGI₂ is synthesized by the PGI₂ synthase (PGIS) enzyme, and its production is determined by measuring its stable metabolite, 6-keto-PGF_1α. An impaired PGI₂ pathway has been observed in PH animal models and in PH Group-I patients; however, there are contradictory results. The aim of this study is to determine whether PH Group-III is associated with altered expression of PGIS and production of PGI₂ in humans. To explore this hypothesis, we measured PGIS expression (by western blot) and PGI₂ production (by ELISA) in a large variety of preparations from the pulmonary circulation including human pulmonary artery, pulmonary vein, distal lung tissue, pulmonary artery smooth muscle cells (hPASMC), and bronchi in PH Group-III (n = 35) and control patients (n = 32). Our results showed decreased PGIS expression and/or 6-keto-PGF_1α levels in human pulmonary artery, hPASMC, and distal lung tissue derived from PH Group-III patients. Moreover, the production of 6-keto-PGF_1α from hPASMC positively correlated with PGIS expression and was inversely correlated with mean pulmonary artery pressure. On the other hand, PH Group-III pulmonary veins and bronchi did not show altered PGI₂ production compared to controls. The deficit in PGIS expression and/or PGI₂ production observed in pulmonary artery and distal lung tissue in PH Group-III patients may have important implications in the pathogenesis and treatment of PH Group-III.

Newer approaches and novel drugs for inhalational therapy for pulmonary arterial hypertension

Introduction: Pulmonary arterial hypertension (PAH) is a progressive disease characterized by remodeling of small pulmonary arteries leading to increased pulmonary arterial pressure. Existing treatments acts to normalize vascular tone via three signaling pathways: the prostacyclin, the endothelin-1, and the nitric oxide. Although over the past 20 years, there has been considerable progress in terms of treatments for PAH, the disease still remains incurable with a disappointing prognosis.Areas covered: This review summarizes the pathophysiology of PAH, the advantages and disadvantages of the inhalation route, and assess the relative advantages various inhaled therapies for PAH. The recent studies concerning the development of controlled-release drug delivery systems loaded with available anti-PAH drugs have also been summarized.Expert opinion: The main obstacles of current pharmacotherapies of PAH are their short half-life, stability, and formulations, resulting in reducing the efficacy and increasing systemic side effects and unknown pathogenesis of PAH. The pulmonary route has been proposed for delivering anti-PAH drugs to overcome the shortcomings. However, the application of approved inhaled anti-PAH drugs is limited. Inhalational delivery of controlled-release nanoformulations can overcome these restrictions. Extensive studies are required to develop safe and effective drug delivery systems for PAH patients.

Ambulatory Transition from Parenteral Prostanoid to Inhaled Treprostinil in Patients with Pulmonary Arterial Hypertension

PURPOSE

The intravenous or subcutaneous delivery of prostanoid drugs for moderate to severe pulmonary arterial hypertension has been fraught with complications and patient dissatisfaction. Combination therapy including inhaled treprostinil is an attractive alternative in clinically stable patients. Uncertainties exist about the patient characteristics and the optimal setting (inpatient versus office/home) for transition.

METHODS

Sixteen stable patients with pulmonary arterial hypertension and favorable risk profile were transitioned from parenteral prostanoid to combination therapy including inhaled treprostinil in the home setting. Nine patients were using intravenous treprostinil, two patients were using subcutaneous treprostinil, and five patients were using intravenous epoprostenol at a median dose of 80 (interquartile range, IQR 72-90), 76.5 (68 and 85), and 28 (IQR 26-30) ng/kg/min respectively. Patients were followed up for a median of 732.5 days after transition (IQR 506.5-1294 days).

RESULTS

Patients tolerated the transition to inhaled treprostinil well without significant change in functional class (81.25% FC I/II before transition vs. 87.5% after), 6-min walk distance [349 m (IQR 226-461 m) to 364 m (IQR 238-565 m), p = 0.09] or NT-proBNP [149 pg/ml (IQR 71.5-383 pg/ml) to 186.5 pg/ml (IQR 83.5-444 pg/ml), p = 0.38]. Hemodynamic data, where available, showed significant improvements in mean pulmonary artery pressure and pulmonary vascular resistance from 36 mmHg (IQR 27-46.5 mmHg) and 5.2 Wood Units (WU) (IQR 3.1-5.6 WU) to 28.5 mmHg (IQR 22-35.5 mmHg) and 3.2 WU (IQR 2.4-4.2 WU) (p-values 0.022 and 0.003). More patients were on triple therapy after transition, and side effects reported were less severe.

CONCLUSION

For select patients, transition from a parenteral prostanoid-based therapy to a combination regimen including inhaled treprostinil in the home setting appears safe and well tolerated.

Efficacy of treprostinil in the SU5416-hypoxia model of severe pulmonary arterial hypertension: haemodynamic benefits are not associated with improvements in arterial remodelling

BACKGROUND AND PURPOSE

Pulmonary arterial hypertension (PAH) is a life-threatening disease that leads to progressive pulmonary hypertension, right heart failure and death. Parenteral prostaglandins (PGs), including treprostinil, a prostacyclin analogue, represent the most effective medical treatment for severe PAH. We investigated the effect of treprostinil on established severe PAH and underlying mechanisms using the rat SU5416 (SU, a VEGF receptor-2 inhibitor)-chronic hypoxia (Hx) model of PAH.

EXPERIMENTAL APPROACH

Male Sprague Dawley rats were injected with SU (20 mg·kg^-1 , s.c.) followed by 3 weeks of Hx (10% O₂ ) to induce severe PAH. Four weeks post-SU injection, baseline right ventricular (RV) systolic pressure (RVSP) was measured, and the rats were randomized to receive vehicle or treprostinil treatment (Trep-100: 100 ng·kg^-1 ·min^-1 or Trep-810: 810 ng·kg^-1 ·min^-1 ). Following 3 weeks of treatment, haemodynamic and echocardiographic assessments were performed, and tissue samples were collected for protein expression and histological analysis.

KEY RESULTS

At week 7, no difference in RVSP or RV hypertrophy was observed between vehicle and Trep-100; however, Trep-810 significantly reduced RVSP and RV hypertrophy. Trep-810 treatment significantly improved cardiac structure and function. Further, a short-term infusion of treprostinil in rats with established PAH at 4 weeks post-SU produced an acute, dose-dependent reduction in RVSP consistent with a vasodilator effect. However, chronic Trep-810 treatment did not alter media wall thickness, degree of vascular occlusion or total vessel count in the lungs.

CONCLUSIONS AND IMPLICATIONS

Treprostinil exerts therapeutic benefits in PAH through decreased vascular resistance and improved cardiac structure and function; however, treprostinil treatment does not have direct impact vascular remodelling.

Switching inhaled iloprost formulations in patients with pulmonary arterial hypertension: the VENTASWITCH Trial

Inhaled iloprost is an effective therapy for patients with pulmonary arterial hypertension (PAH); however, some patients experience extended inhalation times when using the V10 formulation (10.0 µg/mL) to deliver a 5 -µg dose (at mouthpiece) and are at risk of incomplete inhalations and reduced inhalation frequency. VENTASWITCH was an observational, case-crossover study to evaluate inhalation behavior in patients with PAH switched from iloprost V10 to V20 (20.0 µg/mL) formulation for delivering a 5 -µg dose using the I-Neb® AAD® device. Adults with PAH participating in a German Ventavis® (iloprost) patient-support program, who were switched from the V10 to V20 formulation, were enrolled. The co-primary endpoints were mean daily proportion of complete inhalations and mean daily inhalation frequency. The secondary endpoint was mean daily inhalation duration. Data were collected for three months before and after switching. Overall, 63 patients were included. Switching from V10 to V20 resulted in a significant increase in the mean daily proportion of complete inhalations (92% vs. 97%, P < 0.0001) and inhalation frequency (4.6 vs. 4.9 inhalations/day, P = 0.0430), and reduction in mean inhalation duration (11.8 vs. 6.5 min; P < 0.0001). Greater increases in daily proportions of complete inhalations were observed in older patients (≥ 65 vs. < 65 years) and those receiving more (3 vs. < 3) concomitant PAH medications. Switching from V10 to V20 iloprost formulation significantly improved inhalation behavior in patients with PAH and may facilitate improved adherence to therapy.

Nanotherapeutics for Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a devastating and fatal chronic lung disease. While current pharmacotherapies have improved patient quality of life, PAH drugs suffer from limitations in the form of short-term pharmacokinetics, instability, and poor organ specificity. Traditionally, nanotechnology-based delivery strategies have proven advantageous at increasing both circulation lifetimes of chemotherapeutics and accumulation in tumors due to enhanced permeability through fenestrated vasculature. Importantly, increased nanoparticle (NP) accumulation in diseased tissues has been observed pre-clinically in pathologies characterized by endothelial dysfunction and remodeled vasculature, including myocardial infarction and heart failure. Recently, this phenomenon has also been observed in preclinical models of PAH, leading to the exploration of NP-based drug delivery as a therapeutic modality in PAH. Herein, we discussed the advantages of NPs for efficacious treatment of PAH, including heightened therapeutic delivery to diseased lungs for increased drug bioavailability, as well as highlighted innovative nanotherapeutic approaches for PAH.

Reoptimization of the Organocatalyzed Double Aldol Domino Process to a Key Enal Intermediate and Its Application to the Total Synthesis of Δ12 -Prostaglandin J3

Re-investigation of the l-proline catalyzed double aldol cascade dimerization of succinaldehyde for the synthesis of a key bicyclic enal intermediate, pertinent in the field of stereoselective prostaglandin synthesis, is reported. The yield of this process has been more than doubled, from 14 % to a 29 % isolated yield on a multi-gram scale (32 % NMR yield), through conducting a detailed study of the reaction solvent, temperature, and concentration, as well as a catalyst screen. The synthetic utility of this enal intermediate has been further demonstrated through the total synthesis of Δ12 -prostaglandin J3 , a compound with known anti-leukemic properties.

Cefminox, a Dual Agonist of Prostacyclin Receptor and Peroxisome Proliferator-Activated Receptor-Gamma Identified by Virtual Screening, Has Therapeutic Efficacy against Hypoxia-Induced Pulmonary Hypertension in Rats

Prostacyclin receptor (IP) and peroxisome proliferator-activated receptor-gamma (PPARγ) are both potential targets for treatment of pulmonary arterial hypertension (PAH). Expression of IP and PPARγ decreases in PAH, suggesting that screening of dual agonists of IP and PPARγ might be an efficient method for drug discovery. Virtual screening (VS) of potential IP-PPARγ dual-targeting agonists was performed in the ZINC database. Ten of the identified compounds were further screened, and cefminox was found to dramatically inhibit growth of PASMCs with no obvious cytotoxicity. Growth inhibition by cefminox was partially reversed by both the IP antagonist RO113842 and the PPARγ antagonist GW9662. Investigation of the underlying mechanisms of action demonstrated that cefminox inhibits the protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway through up-regulation of the expression of phosphatase and tensin homolog (PTEN, which is inhibited by GW9662), and enhances cyclic adenosine monophosphate (cAMP) production in PASMCs (which is inhibited by RO113842). In a rat model of hypoxia-induced pulmonary hypertension, cefminox displayed therapeutic efficacy not inferior to that of the prostacyclin analog iloprost or the PPARγ agonist rosiglitazone. Our results identified cefminox as a dual agonist of IP and PPARγ that significantly inhibits PASMC proliferation by up-regulation of PTEN and cAMP, suggesting that it has potential for treatment of PAH.

Management of acute subdural hematoma in a patient with portopulmonary hypertension on prostanoid therapy

Background:

Treprostinil is a prostacyclin analog used to treat portopulmonary hypertension (PPHTN) and is one of several drugs shown to increase survival, but results in platelet dysfunction. Little is known about the management of patients on treprostinil who present with an acute subdural hematoma (aSDH). We describe such a case and offer our recommendations on management based on our experience and review of the literature.

Case Description:

A 63-year-old, right-handed female with a history of PPHTN presented with severe headache and was found to have a large left aSDH with midline shift on imaging. She was admitted to the neurosurgical intensive care unit (ICU) where she developed hemiparesis and subsequently underwent emergent decompression. Postoperatively she improved, but several hours after became obtunded and imaging showed reaccumulation of the aSDH, which required reoperation. At 6 months postoperatively she had only a mild hemiparesis and was being reconsidered for treprostinil therapy as a bridge to liver transplant. Only one paper in the literature thus far has reported a patient with an aSDH managed with treprostinil. The authors achieved adequate intraoperative hemostasis without the use of platelet transfusion and lack of complications intraoperatively.

Conclusion:

While concerns related to the risk of bleeding in surgery are valid, intraoperative hemostasis does not appear to be profoundly affected. Surgical intervention should not be delayed and prostanoid therapy discontinued, if possible, postoperatively. Patients should be placed in an intensive care setting with assistance from pulmonary specialists and close monitoring of neurological status and blood pressure.

The safety and pharmacokinetics of rapid iloprost aerosol delivery via the BREELIB nebulizer in pulmonary arterial hypertension

The BREELIB nebulizer was developed for iloprost to reduce inhalation times for patients with pulmonary arterial hypertension (PAH). This multicenter, randomized, unblinded, four-part study compared inhalation time, pharmacokinetics, and acute tolerability of iloprost 5 µg at mouthpiece delivered via BREELIB versus the standard I-Neb nebulizer in 27 patients with PAH. The primary safety outcome was the proportion of patients with a maximum increase in heart rate (HR) ≥ 25% and/or a maximum decrease in systolic blood pressure ≥ 20% within 30 min after inhalation. Other safety outcomes included systolic, diastolic, and mean blood pressure, HR, oxygen saturation, and adverse events (AEs). Median inhalation times were considerably shorter with BREELIB versus I-Neb (2.6 versus 10.9 min; n = 24). Maximum iloprost plasma concentration and systemic exposure (area under the plasma concentration–time curve) were 77% and 42% higher, respectively, with BREELIB versus I-Neb. Five patients experienced a maximum systolic blood pressure decrease ≥ 20%, four with BREELIB (one mildly and transiently symptomatic), and one with I-Neb; none required medical intervention. AEs reported during the study were consistent with the known safety profile of iloprost. The BREELIB nebulizer offers reduced inhalation time, good tolerability, and may improve iloprost aerosol therapy convenience and thus compliance for patients with PAH.

Practical considerations for therapies targeting the prostacyclin pathway

Therapies that target the prostacyclin pathway play a key role in the treatment of both early- and late-stage pulmonary arterial hypertension, and provide significant clinical benefits for patients. A number of agents have been approved, which are administered via intravenous, subcutaneous, inhaled or oral routes. The use of these therapies is associated with practical challenges, relating to the need for up-titration and their routes of administration. We discuss here a number of measures that can be taken to support patients and healthcare professionals in order to address the complexities of using these therapies and to encourage compliance. Providing patients with timely information and education, together with practical advice on managing their medication and associated equipment, assists patients with day-to-day management of therapy. Referral to patient associations and support groups can be of further benefit. With an effective management plan and an experienced multidisciplinary team, the use of therapies that target the prostacyclin pathway can be optimised.

Practical support for patients and HCPs to facilitate the use of therapies that target the PGI₂ pathway in PAHhttp://ow.ly/468S305Dl6m

Portopulmonary hypertension

Portopulmonary hypertension (PoPH) refers to the condition that pulmonary arterial hypertension (PAH) occur in the stetting of portal hypertension. The development of PoPH is thought to be independent of the severity of portal hypertension or the etiology or severity of liver disease. PoPH results from excessive vasoconstriction, vascular remodeling, and proliferative and thrombotic events within the pulmonary circulation that lead to progressive right ventricular failure and ultimately to death. Untreated PoPH is associated with a poor prognosis. As PoPH is frequently asymptomatic or symptoms are generally non-specific, patients should be actively screened for the presence of PoPH. Two-dimensional transthoracic echocardiography is a useful non-invasive screening tool, but a definitive diagnosis requires invasive hemodynamic confirmation by right heart catheterization. Despite a dearth of randomized, prospective data, an ever-expanding clinical experience shows that patients with PoPH benefit from therapy with PAH-specific medications including with endothelin receptor antagonists, phosphodiesterase-5 inhibitors, and/or prostanoids. Due to high perioperative mortality, transplantation should be avoided in those patients who have severe PoPH that is refractory to medical therapy.

Clinical use of extended-release oral treprostinil in the treatment of pulmonary arterial hypertension

The development of parenteral prostacyclin therapy marked a dramatic breakthrough in the treatment of pulmonary arterial hypertension (PAH). Intravenous (IV) epoprostenol was the first PAH specific therapy and to date, remains the only treatment to demonstrate a mortality benefit. Because of the inherent complexities and risks of treating patients with continuous infusion IV therapy, there is great interest in the development of an oral prostacyclin analog that could mimic the benefits of IV therapy. Herein, we highlight the development of oral prostacyclin therapy, focusing on oral treprostinil, the only US Food and Drug Administration approved oral prostacyclin. Recent Phase III clinical trials have shown the drug to improve exercise tolerance in treatment-naïve PAH patients, but not patients on background oral therapy. Oral treprostinil appears to be most efficacious at higher doses, but its side effect profile and complexities with dosing complicate its use. While oral treprostinil’s current therapeutic role in PAH remains unclear, ongoing studies of this class of medication should help clarify their role in the treatment of PAH.

Recent advances in targeting the prostacyclin pathway in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a severe disease characterised by increased pulmonary vascular resistance, which leads to restricted pulmonary arterial blood flow and elevated pulmonary arterial pressure. In patients with PAH, pulmonary concentrations of prostacyclin, a prostanoid that targets several receptors including the IP prostacyclin receptor, are reduced. To redress this balance, epoprostenol, a synthetic prostacyclin, or analogues of prostacyclin have been given therapeutically. These therapies improve exercise capacity, functional class and haemodynamic parameters. In addition, epoprostenol improves survival among patients with PAH. Despite their therapeutic benefits, treatments that target the prostacyclin pathway are underused. One key factor is their requirement for parenteral administration: continuous intravenous administration can lead to embolism and thrombosis; subcutaneous administration is associated with infusion-site pain; and inhalation is time consuming, requiring multiple daily administrations. Nevertheless, targeting the prostacyclin pathway is an important strategy for the management of PAH. The development of oral therapies for this pathway, as well as more user-friendly delivery devices, may alleviate some of the inconveniences. Continued improvements in therapeutic options will enable more patients with PAH to receive medication targeting the prostacyclin pathway.