Selexipag, a selective prostacyclin receptor agonist in pulmonary arterial hypertension: a pharmacology review

Transitioning intravenous epoprostenol to oral selexipag in idiopathic pulmonary arterial hypertension: a case report

Intravenous (i.v.) prostacyclin is the cornerstone treatment in high-risk pulmonary arterial hypertension (PAH) patients. Selexipag is an orally available prostacyclin receptor agonist. Limited data are available regarding the feasibility of transitioning from i.v. epoprostenol to selexipag. A 50-year-old woman with idiopathic PAH was diagnosed in a World Health Organization (WHO) Functional Class (FC) IV. She improved with upfront triple combination therapy, including i.v. epoprostenol. Over 2 years of follow-up, the patient remained at low risk and expressed strong preference towards oral therapies. After careful risk-benefit clinical consideration, she was transitioned from i.v. epoprostenol to selexipag. Selexipag was started at dosage of 200 μg twice daily (b.i.d.) and titrated up to 1600 μg b.i.d. over 8 weeks (up-titration of 200 μg b.i.d. every week). Simultaneously, i.v. epoprostenol was down-titrated 3.0 ng/kg/min every week from a dosage of 27.5 ng/kg/min. The transition occurred under strict medical surveillance and was well tolerated. One year after discontinuation of epoprostenol, the patient remains in WHO FC I and has no signs of clinical deterioration. Although not generalizable to most PAH patients, this case highlights that a carefully planned transition from epoprostenol to selexipag is feasible in selected low-risk patients within a shared medical decision-making framework.

Systemic Sclerosis: From Pathophysiology to Novel Therapeutic Approaches

Systemic sclerosis (SSc) is a systemic, immune-mediated chronic disorder characterized by small vessel alterations and progressive fibrosis of the skin and internal organs. The combination of a predisposing genetic background and triggering factors that causes a persistent activation of immune system at microvascular and tissue level is thought to be the pathogenetic driver of SSc. Endothelial alterations with subsequent myofibroblast activation, excessive extracellular matrix (ECM) deposition, and unrestrained tissue fibrosis are the pathogenetic steps responsible for the clinical manifestations of this disease, which can be highly heterogeneous according to the different entity of each pathogenic step in individual subjects. Although substantial progress has been made in the management of SSc in recent years, disease-modifying therapies are still lacking. Several molecular pathways involved in SSc pathogenesis are currently under evaluation as possible therapeutic targets in clinical trials. These include drugs targeting fibrotic and metabolic pathways (e.g., TGF-β, autotaxin/LPA, melanocortin, and mTOR), as well as molecules and cells involved in the persistent activation of the immune system (e.g., IL4/IL13, IL23, JAK/STAT, B cells, and plasma cells). In this review, we provide an overview of the most promising therapeutic targets that could improve the future clinical management of SSc.

A Case Report of a Patient With Pulmonary Arterial Hypertension Transitioned From Inhaled Iloprost to Selexipag

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by elevated pulmonary vascular resistance that can lead to right ventricular failure and death. The use of medications that affect the prostacyclin pathway is an important treatment strategy in PAH. Inhaled iloprost is a prostacyclin analogue, and selexipag is an oral, non-prostanoid, prostacyclin IP receptor agonist. Data are limited on transitioning patients from inhaled iloprost to selexipag. In this case report, we describe the successful transition of a 57-year-old female with heritable PAH from inhaled iloprost to selexipag over 8 weeks in an out-patient setting. After initiation of selexipag, the patient's inhaled iloprost dose was gradually reduced and eventually discontinued. The patient tolerated the transition well with stable symptoms, 6-minute walk distance, and pulmonary hemodynamics. Additional studies are needed to better define the comparative efficacy and safety of inhaled iloprost and selexipag.

Druggable Prostanoid Pathway

Prostanoids (prostaglandins, prostacyclin and thromboxane) belong to the oxylipin family of biologically active lipids generated from arachidonic acid (AA). Protanoids control numerous physiological and pathological processes. Cyclooxygenase (COX) is a rate-limiting enzyme involved in the conversion of AA into prostanoids. There are two COX isozymes: the constitutive COX-1 and the inducible COX-2. COX-1 and COX-2 have similar structures, catalytic activities, and subcellular localizations but differ in patterns of expression and biological functions. Non-selective COX-1/2 or traditional, non-steroidal anti-inflammatory drugs (tNSAIDs) target both COX isoforms and are widely used to relieve pain, fever and inflammation. However, the use of NSAIDs is associated with various side effects, particularly in the gastrointestinal tract. NSAIDs selective for COX-2 inhibition (coxibs) were purposefully designed to spare gastrointestinal toxicity, but predisposed patients to increased cardiovascular risks. These health complications from NSAIDs prompted interest in the downstream effectors of the COX enzymes as novel drug targets. This chapter describes various safety issues with tNSAIDs and coxibs, and discusses the current development of novel classes of drugs targeting the prostanoid pathway, including nitrogen oxide- and hydrogen sulfide-releasing NSAIDs, inhibitors of prostanoid synthases, dual inhibitors, and prostanoid receptor agonists and antagonists.

Systemic Sclerosis Pathogenesis and Emerging Therapies, beyond the Fibroblast

Systemic sclerosis (SSc) is a complex rheumatologic autoimmune disease in which inflammation, fibrosis, and vasculopathy share several pathogenic pathways that lead to skin and internal organ damage. Recent findings regarding the participation and interaction of the innate and acquired immune system have led to a better understanding of the pathogenesis of the disease and to the identification of new therapeutic targets, many of which have been tested in preclinical and clinical trials with varying results. In this manuscript, we review the state of the art of the pathogenesis of this disease and discuss the main therapeutic targets related to each pathogenic mechanism that have been discovered so far.

Pulmonary hypertension and cardiac anesthesia: Anesthesiologist's perspective

Perioperative management of pulmonary hypertension remains one of the most challenging scenarios during cardiac surgery. It is associated with high morbidity and mortality due to right ventricular failure, arrhythmias, myocardial ischemia, and intractable hypoxia. Therefore, this review article is intended toward the anesthetic considerations in the perioperative period, with particular emphasis on the selection of technique and choice of anesthesia with maintenance, anesthetic drugs, and the recent intraoperative recommendations for prevention and treatment of pulmonary hypertensive crisis.

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.