Selexipag, an Oral Prostacyclin-Receptor Agonist for Pulmonary Arterial Hypertension

[Experience with Selexipag to Treat Pulmonary Arterial Hypertension]

Aim To present an own experience in using a medication selexipag in patients with pulmonary arterial hypertension (PAH) included into the V. A. Almazov National Medical Research Center registry and participating in the GRIPHON and GRIPHON OL clinical studies.Material and methods 26 patients with PAH were included into this study since 2010: 20 patients with idiopathic PAH, 4 patients with PAH associated with systemic scleroderma, and 2 patients with corrected congenital heart defects. At the time of randomization, 19 patients had been receiving therapy with phosphodiesterase type 5 inhibitors for at least one month. Among the patients treated with selexipag (n=14), 4 patients reached a high individual maintenance dose (1200-1600 µg b.i.d.), 4 patients reached a medium dose (600-1000 µg b.i.d.), and 6 patients reached a low dose (200-400 µg b.i.d.).Results The selexipag therapy exerted a positive effect on secondary endpoints, specifically, on changes in the functional class of pulmonary hypertension, serum concentration of NT-proBNP, and physical working capacity of patients. Adverse events associated with the selexipag treatment, which resulted in termination of study participation, were observed in one patient.Conclusion To achieve the main goal of drug therapy, low risk of death with selexipag it is critical to observe the titration schedule and to aim at reaching the highest individual maintenance dose.

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.

What Is the Role of Oral Prostacyclin Pathway Medications in Pulmonary Arterial Hypertension Management?

PURPOSE OF REVIEW

Prostacyclin pathway medications have been shown to be highly efficacious in the treatment of pulmonary arterial hypertension (PAH) through multiple prospective clinical trials and more than two decades of clinical experience. The strongest support for prostacyclin use in PAH management is with parenteral administration. Numerous risks and limitations of parenteral delivery systems as well as significant patient burdens restrict widespread parenteral use. Highly effective and tolerable oral prostacyclin preparations to manage PAH have long been sought. We review the development of the oral prostacyclin agents beraprost, treprostinil, and selexipag and including current indications and limitations. Research into new approaches to the management of PAH, expanding indications for existing agents, and development of novel agents are also discussed.

RECENT FINDINGS

Two oral prostacyclin pathway medications, oral treprostinil and selexipag, were FDA approved in December 2013 and 2015, respectively. Current guidelines recommend use of selexipag in WHO-FC II and III (class 1, level B recommendation) and oral treprostinil in WHO-FC III (class 2b, level B recommendation). The use of these medications is challenging due to complexity in dosing and their side effect profiles which limit patient tolerability and acceptance. There is a promising role for oral prostacyclin pathway medications in patients with PAH. Future investigations are underway of alternative dose regimens and transitioning from parenteral therapies in order to improve efficacy and tolerability.