mre-269 and Hypertension--Pulmonary

Selexipag is the first oral, non-prostanoid, selective prostacyclin receptor (IP receptor) agonist, approved for the long-term treatment of pulmonary arterial hypertension (PAH) in adult patients. Areas covered: This article reviews the clinical pharmacology, efficacy, and safety of selexipag in the treatment of PAH. Expert opinion: Selexipag is the first oral drug that selectively targets the prostacyclin pathway, and has evidence of long-term efficacy and safety. In the global phase 3 study GRIPHON (NCT01106014) in PAH patients, selexipag significantly reduced the risk of the primary composite outcome of morbidity/mortality (M/M). The adverse events in the selexipag group were consistent with the known side effects of prostacyclin, including headache, nausea, jaw pain, and diarrhea. Importantly, selexipag was efficacious and safe irrespective of whether or not patients were already receiving other PAH therapies. With selexipag approval, triple oral combination therapy addressing three important pathways is available for patients with PAH. Selexipag has one major metabolite, ACT-333679, which is also a selective IP receptor agonist, with 37-fold higher potency than selexipag. Pharmacokinetic properties of ACT-333679 permit twice-daily dosing of selexipag, providing a more convenient treatment compared to prostacyclin or its analogs. For patients with moderate hepatic impairment a once-daily regimen is recommended.

Topics: Acetamides; Acetates; Administration, Oral; Adult; Animals; Antihypertensive Agents; Drug Administration Schedule; Drug Therapy, Combination; Humans; Hypertension, Pulmonary; Pyrazines

Pulmonary hypertension is defined by a mean pulmonary artery pressure ≥25 mm Hg at rest. Management of pulmonary arterial hypertension (PAH) includes specific drug therapy with calcium channel blockers in vasoreactive patients, or drugs approved for PAH in non-reactive patients that target the endothelin, nitric-oxide and prostacyclin pathways. Areas covered: The review covers receptor selectivity, pharmacokinetics, pharmacodynamics and adverse effects (AEs) of intravenous (IV) epoprostenol (synthetic prostacyclin); the prostacyclin analogs iloprost, beraprost, and treprostinil administered by IV, subcutaneous, inhaled or oral routes; and the oral selective prostacyclin receptor agonist selexipag. Expert commentary: Development of a selective prostacyclin receptor agonist has aimed at identifying compounds with improved pharmacological properties. The high selectivity of selexipag, and its active metabolite ACT-333679, for the prostacyclin receptor, in conjunction with pharmacokinetic properties that reduce peak-trough fluctuations and the up-titration regimen used at the start of treatment, are collectively considered to minimize AEs associated with prostacyclin use. In a large phase 3 study, selexipag-associated AEs were consistent with those observed with drugs that target the prostacyclin pathway, and mainly mild to moderate in severity. The dosing flexibility afforded by oral selexipag may facilitate achieving the maximum therapeutic effect with acceptable tolerability in patients with PAH.

Topics: Acetamides; Acetates; Administration, Oral; Animals; Antihypertensive Agents; Drug Design; Humans; Hypertension, Pulmonary; Pyrazines; Receptors, Epoprostenol

Selexipag is a first-in-class orally available selective non-prostanoid IP receptor agonist. This review was based on a PubMed search and focuses on the potential role of selexipag in the treatment of pulmonary arterial hypertension (PAH).. Selexipag is rapidly hydrolyzed to an active metabolite, ACT-333679. Both selexipag and its metabolite are highly selective for the IP receptor compared with other prostanoid receptors. This selectivity for the IP receptor offers the potential for improved tolerability with selexipag, as side effects (e.g., nausea and vomiting) that might result from activation of the other prostanoid receptors may be minimized. In addition, the selexipag metabolite has a half-life of 7.9 h, thus permitting oral dosing twice daily. Selexipag showed effects on pharmacodynamic end points obtained with right heart catheterization in a Phase II trial in patients with PAH, and is being evaluated in the ongoing Phase III trial (GRIPHON trial, Clinicaltrials.gov NCT01106014).. The signal of a beneficial effect of selexipag on disease progression may become more robust for long term under prolonged exposure. Pending the GRIPHON trial results, selexipag could provide a convenient first-line prostacyclin treatment option for patients with PAH.

Topics: Acetamides; Acetates; Administration, Oral; Clinical Trials, Phase II as Topic; Clinical Trials, Phase III as Topic; Familial Primary Pulmonary Hypertension; Humans; Hypertension, Pulmonary; Prostaglandins I; Pyrazines; Receptors, Prostaglandin; Signal Transduction

Selexipag (Uptravi) is an oral selective IP prostacyclin receptor agonist approved for the treatment of pulmonary arterial hypertension (PAH). The pivotal GRIPHON study was the largest clinical study ever conducted in PAH patients, providing long-term data from 1,156 patients. PAH comedication did not affect exposure to selexipag, while exposure to its active metabolite ACT-333679 was reduced by 30% when taken in combination, clinically not relevant in the context of individual dose up-titration. Using log-linear regression models linking model-predicted steady-state exposure to pharmacodynamics (PD), exposure to selexipag and ACT-333679 showed some statistically significant, albeit not clinically relevant, effects on exercise capacity, laboratory values, and the occurrence of prostacyclin-related adverse events, but not on vital signs or adverse events denoting hemorrhage. Using suitable modeling techniques, the GRIPHON study yielded clinically relevant data with limited burden of pharmacokinetics (PK) blood sampling, demonstrating that PK/PD modeling enables firm conclusions even with sparse PK and PD sampling.

Topics: Acetamides; Acetates; Adult; Antihypertensive Agents; Bilirubin; Double-Blind Method; Exercise Tolerance; Female; Humans; Hypertension, Pulmonary; Leukocyte Count; Male; Models, Biological; Natriuretic Peptide, Brain; Peptide Fragments; Pyrazines; Treatment Outcome

The design and synthesis of a new series of potent non-prostanoid IP receptor agonists that showed oral efficacy in the rat monocrotaline model of pulmonary arterial hypertension (PAH) are described. Detailed profiling of a number of analogues resulted in the identification of 5c (ralinepag) that has good selectivity in both binding and functional assays with respect to most members of the prostanoid receptor family and a more modest 30- to 50-fold selectivity over the EP3 receptor. In our hands, its potency and efficacy are comparable or superior to MRE269 (the active metabolite of the clinical compound NS-304) with respect to in vitro IP receptor dependent cAMP accumulation assays. 5c had an excellent PK profile across species. Enterohepatic recirculation most probably contributes to a concentration-time profile after oral administration in the cynomolgus monkey that showed a very low peak-to-trough ratio. Following the identification of an acceptable solid form, 5c was selected for further development for the treatment of PAH.

Topics: Acetates; Administration, Oral; Animals; Biological Availability; Carbamates; Drug Discovery; Hypertension, Pulmonary; Rats; Receptors, Prostaglandin; Structure-Activity Relationship

Prostacyclin (PGI

Topics: Acetamides; Acetates; Animals; beta-Arrestins; Cell Proliferation; CHO Cells; Contractile Proteins; Cricetinae; Cricetulus; Cyclic AMP; Epoprostenol; Extracellular Matrix; Humans; Hypertension, Pulmonary; Iloprost; Male; Muscle Contraction; Muscle Relaxation; Pyrazines; Rats; Rats, Inbred SHR; Rats, Wistar; Receptors, Epoprostenol

Prostacyclin controls cardiovascular function via activation of the prostacyclin receptor. Decreased prostacyclin production occurs in several cardiovascular diseases. However, the clinical use of prostacyclin and its analogues is complicated by their chemical and metabolic instability. A medicinal chemistry program searched for novel nonprostanoid prostacyclin receptor agonists not subject to these limitations. A compound with a diphenylpyrazine structural core was synthesized. Metabolic stability and agonist potency were optimized through modification of the linear side chain. Compound 12b (MRE-269, ACT-333679) was identified as a potent and highly selective prostacyclin receptor agonist. Replacement of the terminal carboxyl group with an N-acylsulfonamide group yielded parent compound 26a (selexipag, NS-304, ACT-293987), which is orally active and provides sustained plasma exposure of 12b. Compound 26a was developed for the treatment of pulmonary arterial hypertension and shown to reduce the risk of the composite morbidity/mortality end point in a phase 3 event-driven clinical trial.

Topics: Acetamides; Acetates; Administration, Oral; Animals; CHO Cells; Clinical Trials, Phase II as Topic; Clinical Trials, Phase III as Topic; Cricetulus; Dogs; Double-Blind Method; Haplorhini; Humans; Hypertension, Pulmonary; Myocytes, Smooth Muscle; Platelet Aggregation Inhibitors; Pulmonary Artery; Pyrazines; Randomized Controlled Trials as Topic; Rats; Receptors, Epoprostenol; Structure-Activity Relationship

{4-[(5,6-Diphenylpyrazin-2-yl)(isopropyl)amino]butoxy}acetic acid (ACT-333679) is the main metabolite of the selective prostacyclin (PGI(2)) receptor (IP receptor) agonist selexipag. The goal of this study was to determine the influence of IP receptor selectivity on the vasorelaxant efficacy of ACT-333679 and the PGI(2) analog treprostinil in pulmonary artery under conditions associated with pulmonary arterial hypertension (PAH). Selexipag and ACT-333679 evoked full relaxation of pulmonary artery from control and monocrotaline (MCT)-PAH rats, and ACT-333679 relaxed normal pulmonary artery contracted with either endothelin-1 (ET-1) or phenylephrine. In contrast, treprostinil evoked weaker relaxation than ACT-333679 of control pulmonary artery and failed to induce relaxation of pulmonary artery from MCT-PAH rats. Treprostinil did not evoke relaxation of normal pulmonary artery contracted with either ET-1 or phenylephrine. Expression of prostaglandin E(3) (EP(3)) receptor mRNA was increased in pulmonary artery from MCT-PAH rats. In contraction experiments, the selective EP(3) receptor agonist sulprostone evoked significantly greater contraction of pulmonary artery from MCT-PAH rats compared with control rats. The presence of a threshold concentration of ET-1 significantly augmented the contractile response to sulprostone in normal pulmonary artery. ACT-333679 did not evoke direct contraction of rat pulmonary artery, whereas treprostinil evoked concentration-dependent contraction that was inhibited by the EP(3) receptor antagonist (2E)-3-(3',4'-dichlorobiphenyl-2-yl)-N-(2-thienylsulfonyl)acrylamide. Antagonism of EP(3) receptors also revealed a relaxant response to treprostinil in normal pulmonary artery contracted with ET-1. These data demonstrate that the relaxant efficacy of the selective IP receptor agonist selexipag and its metabolite ACT-333679 is not modified under conditions associated with PAH, whereas relaxation to treprostinil may be limited in the presence of mediators of disease.

Topics: Acetamides; Acetates; Alprostadil; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Epoprostenol; Hypertension, Pulmonary; In Vitro Techniques; Male; Pulmonary Artery; Pyrazines; Rats; Rats, Wistar; Receptors, Epoprostenol; Vasoconstrictor Agents; Vasodilation; Vasodilator Agents

2-{4-[(5,6-Diphenylpyrazin-2-yl)(isopropyl)amino]butoxy}-N-(methylsulfonyl)acetamide (NS-304) is an orally available, long-acting nonprostanoid prostacyclin receptor (IP receptor) agonist prodrug. In a rat model of pulmonary hypertension induced by monocrotaline (MCT), NS-304 ameliorated vascular endothelial dysfunction, pulmonary arterial wall hypertrophy, and right ventricular hypertrophy, and it elevated right ventricular systolic pressure and improved survival. {4-[(5,6-Diphenylpyrazin-2-yl)(isopropyl)amino]butoxy}acetic acid (MRE-269), the active form of NS-304, is much more selective for the IP receptor than are the prostacyclin analogs beraprost and iloprost, which also have high affinity for the EP(3) receptor. To investigate the effect of receptor selectivity on vasodilation of the pulmonary artery, we assessed the relaxant response to these IP agonists in rats. MRE-269 induced vasodilation equally in large pulmonary arteries (LPA) and small pulmonary arteries (SPA), whereas beraprost and iloprost induced less vasodilation in SPA than in LPA. An EP(3) agonist, sulprostone, induced SPA and LPA vasoconstriction, and an EP(3) antagonist attenuated the vasoconstriction. Beraprost showed EP(3) agonism and induced LPA and SPA vasoconstriction, whereas the EP(3) antagonist inhibited this vasoconstriction and enhanced beraprost- and iloprost-induced SPA vasodilation. These findings suggest that the EP(3) agonism of beraprost and iloprost interfered with the SPA vasodilation resulting from their IP receptor agonism. Endothelium removal markedly attenuated the vasodilation induced by beraprost, but not that induced by MRE-269 or iloprost. Moreover, the vasodilation induced by beraprost and iloprost, but not that induced by MRE-269, was more strongly attenuated in LPA from MCT-treated rats than from normal rats. NS-304 is a promising alternative medication for pulmonary arterial hypertension with prospects for good patient compliance.

Topics: Acetamides; Acetates; Animals; Antihypertensive Agents; CHO Cells; Cricetinae; Cricetulus; Dose-Response Relationship, Drug; Humans; Hypertension, Pulmonary; In Vitro Techniques; Male; Prodrugs; Pulmonary Artery; Pyrazines; Rats; Rats, Sprague-Dawley; Receptors, Epoprostenol; Vasodilation