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.

Loss of response to calcium channel blockers after long-term follow-up treatment in patients with idiopathic pulmonary arterial hypertension.

Idiopathic pulmonary arterial hypertension (PAH) patients with a positive response to acute vasodilator challenge and a clinical response to calcium channel blockers (CCBs) for at least one year are traditionally designated true responders. Nevertheless, little is known about a sustained response to CCBs over longer periods of time. We evaluated the loss of response to CCBs after long-term treatment in a cohort of idiopathic PAH patients previously classified as being true responders. Our data suggest that idiopathic PAH patients can lose clinical response to CCBs even after one year of clinical stability, reinforcing the need for constant multidimensional reevaluation to assess the need for targeted PAH therapies and to classify these patients correctly.

Pulmonary hypertension inhaled therapies: An updated review.

Treatments of pulmonary hypertension (PH) continue to evolve with approval of new therapies. The currently FDA approved inhaled PH therapies include inhaled iloprost for group 1 pulmonary arterial hypertension (PAH), inhaled treprostinil solution and treprostinil dry powder inhaler for both group 1 PAH and group 3 PH associated with interstitial lung disease (PH-ILD). Inhaled treprostinil was recently approved for group 3 PH-ILD based on the results of INCREASE trial and the newer formulation of treprostinil dry powder that comes with a new inhaler was recently approved for both group 1 PAH and group 3 PH-ILD based on BREEZE study. The pipeline for inhaled PH therapies includes several promising molecules that can enrich the current PH therapeutic era and mitigate several systemic side effects by directly delivering the drug to the target organ. In this review article we summarize the evidence for the currently approved inhaled PAH/PH therapies, discuss the available inhalation devices, present a roadmap for successful treatment strategy, and present several inhaled PAH/PH therapies in the pipeline.

Targeting cyclin-dependent kinases for the treatment of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a devastating disease with poor prognosis and limited therapeutic options. We screened for pathways that may be responsible for the abnormal phenotype of pulmonary arterial smooth muscle cells (PASMCs), a major contributor of PAH pathobiology, and identified cyclin-dependent kinases (CDKs) as overactivated kinases in specimens derived from patients with idiopathic PAH. This increased CDK activity is confirmed at the level of mRNA and protein expression in human and experimental PAH, respectively. Specific CDK inhibition by dinaciclib and palbociclib decreases PASMC proliferation via cell cycle arrest and interference with the downstream CDK-Rb (retinoblastoma protein)-E2F signaling pathway. In two experimental models of PAH (i.e., monocrotaline and Su5416/hypoxia treated rats) palbociclib reverses the elevated right ventricular systolic pressure, reduces right heart hypertrophy, restores the cardiac index, and reduces pulmonary vascular remodeling. These results demonstrate that inhibition of CDKs by palbociclib may be a therapeutic strategy in PAH.

LRP1 promotes synthetic phenotype of pulmonary artery smooth muscle cells in pulmonary hypertension.

Pulmonary hypertension (PH) is characterized by a thickening of the distal pulmonary arteries caused by medial hypertrophy, intimal proliferation and vascular fibrosis. Low density lipoprotein receptor-related protein 1 (LRP1) maintains vascular homeostasis by mediating endocytosis of numerous ligands and by initiating and regulating signaling pathways. Here, we demonstrate the increased levels of LRP1 protein in the lungs of idiopathic pulmonary arterial hypertension (IPAH) patients, hypoxia-exposed mice, and monocrotaline-treated rats. Platelet-derived growth factor (PDGF)-BB upregulated LRP1 expression in pulmonary artery smooth muscle cells (PASMC). This effect was reversed by the PDGF-BB neutralizing antibody or the PDGF receptor antagonist. Depletion of LRP1 decreased proliferation of donor and IPAH PASMC in a ß1-integrin-dependent manner. Furthermore, LRP1 silencing attenuated the expression of fibronectin and collagen I and increased the levels of α-smooth muscle actin and myocardin in donor, but not in IPAH, PASMC. In addition, smooth muscle cell (SMC)-specific LRP1 knockout augmented α-SMA expression in pulmonary vessels and reduced SMC proliferation in 3D ex vivo murine lung tissue cultures. In conclusion, our results indicate that LRP1 promotes the dedifferentiation of PASMC from a contractile to a synthetic phenotype thus suggesting its contribution to vascular remodeling in PH.

The use of antidepressants and the risk of idiopathic pulmonary arterial hypertension.

BACKGROUND: Serotonin has been implicated in the development of idiopathic pulmonary arterial hypertension (IPAH). Drugs modulating serotonin pathways, including antidepressants, have been associated with the incidence of IPAH, with conflicting reports as to the direction of the effect. We aimed to determine whether antidepressant exposure is associated with the incidence of IPAH. METHODS: A nested case-control study was conducted using the United Kingdom Clinical Practice Research Datalink and the Hospital Episodes Statistics repository between January 1, 1988 and September 30, 2011. Incident cases of IPAH were identified and matched to all controls in the case's risk set on age, sex, general practice, and date of registration with the practice. Rate ratios (RRs) and 95% confidence intervals (CIs) were estimated for the use of antidepressants on the risk of IPAH, with an 18-month lag period before the diagnosis. RESULTS: One hundred ninety-five IPAH cases were identified (incidence 3.84/million per year). Use of any antidepressant was associated with a 67% increased risk of IPAH (RR, 1.67; 95% CI, 1.17-2.37). The rate of IPAH was similar across antidepressant classes, whether with selective serotonin reuptake inhibitors (SSRIs) (RR, 1.67; 95% CI, 1.09-2.57) or non-SSRI antidepressants (RR, 1.66; 95% CI, 1.07-2.59). In sensitivity and exploratory analyses, no change in risk was observed with different lag times, serotonin transporter affinities, or durations of exposure. CONCLUSIONS: The use of antidepressants was associated with a significantly increased risk of IPAH. However, the consistency of this risk across all antidepressants and absence of a dose-response relationship suggests a noncausal association.

Large granular lymphocytosis during dasatinib therapy.

Dasatinib is a second generation tyrosine kinase inhibitor (TKI) approved for clinical use in patients with imatinib-resistant chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL). Large granular lymphocytes (LGLs) are medium to large cells with eccentric nuclei and abundant cytoplasm with coarse azurophilic granules. LGL lymphocytosis is caused by a proliferation of cytotoxic (CD8+) T cells and/or NK cells. In a proportion of CML and Ph(+) ALL patients, there is a significant expansion of LGLs during dasatinib therapy. LGL lymphocytosis is seen in some cases with fevers, colitis, and pleural effusions (PE), suggesting an aberrant immune response mediated by these LGLs. LGLs may participate in the elimination of the residual leukemic cells, and LGL clonal expansion is associated with excellent, long-lasting therapy responses in dasatinib-treated patients. For a more comprehensive analysis, we analyzed the morphologic, phenotypic, clinical, and functional features of the LGL subsets amplified in vivo during dasatinib therapy.

Present and future treatment strategies for pulmonary arterial hypertension : focus on phosphodiesterase-5 inhibitors.

Idiopathic pulmonary arterial hypertension (IPAH) is a rare progressive disorder historically associated with mortality in <3 years post-diagnosis. The etiology of PAH is complex, multifactorial, and likely involves the interplay between genetic and environmental factors. These are reviewed with emphasis on the nitric oxide pathway. Use of treatment modalities including vasodilator therapy have resulted in improved symptoms, hemodynamics, and survival in these patients. Vasodilators, including the calcium channel antagonists, prostanoids, and endothelin receptor antagonists, have been used to counteract potential imbalances in vasoactive mediators in PAH patients; all have produced improved long-term symptomatology and hemodynamics. Only the prostanoid epoprostenol has improved survival in IPAH patients. Although these medications have worked well in many patients with PAH, each of them has limitations. The phosphodiesterase-5 (PDE-5) inhibitors are a relatively new form of treatment for PAH. They are designed to potentiate the effects of cyclic guanosine monophosphate, thereby mimicking endogenous nitric oxide within the vasculature. PDE-5 inhibitors are selective pulmonary vasodilators effective in animal models of pulmonary hypertension. The published clinical studies evaluating their use have been small in size to date but appear to demonstrate benefit. The recently completed 12-week randomized placebo-controlled Sildenafil Use in Pulmonary Hypertension (SUPER-1) trial demonstrated improvement in 6-minute walk distance and hemodynamics in patients receiving sildenafil. These data suggest that the PDE-5 inhibitors are effective in treating PAH and that it is likely that their usage will increase over time. The purpose of this review is to present a current view of the pathogenesis and treatment of PAH, with an emphasis on the use of PDE-5 inhibitors in these patients.