Switching from sildenafil to riociguat for the treatment of PAH and inoperable CTEPH: Real-life experiences

Evolution and New Perspectives of Balloon Pulmonary Angioplasty in CTEPH

Chronic thromboembolic pulmonary disease (CTEPD) and chronic thromboembolic pulmonary hypertension (CTEPH) are debilitating complications of acute pulmonary embolism (PE) that are characterized by fibrosis and organization of the thrombotic material within pulmonary artery branches. This pathology leads to increased right ventricular afterload and dead space ventilation, posing a risk of progressive pulmonary hypertension, right-sided heart failure, and potentially death if left untreated. Pulmonary endarterectomy (PTE) is a technically complex open-heart surgery considered to be a first-line treatment as it is a potentially curative therapy. Although PTE is highly successful in proximal disease, it may not reach the very distal branches. On the other hand, pulmonary vasodilator therapy is very effective in improving microvasculopathy but does not address the obstructive fibrotic component of the larger vessels. Balloon pulmonary angioplasty (BPA) is a novel percutaneous revascularization therapy in which traditional angioplasty techniques are used to relieve obstruction in the pulmonary arteries. This review discusses the currently accepted indications, patient selection, technical considerations, outcomes, and complications of contemporary BPA. This review will address knowledge gaps and future perspectives in BPA research.

Current Overview of the Biology and Pharmacology in Sugen/Hypoxia-Induced Pulmonary Hypertension in Rats

The Sugen 5416/hypoxia (Su/Hx) rat model of pulmonary arterial hypertension (PAH) demonstrates most of the distinguishing features of PAH in humans, including increased wall thickness and obstruction of the small pulmonary arteries along with plexiform lesion formation. Recently, significant advancement has been made describing the epidemiology, genomics, biochemistry, physiology, and pharmacology in Su/Hx challenge in rats. For example, there are differences in the overall reactivity to Su/Hx challenge in different rat strains and only female rats respond to estrogen treatments. These conditions are also encountered in human subjects with PAH. Also, there is a good translation in both the biochemical and metabolic pathways in the pulmonary vasculature and right heart between Su/Hx rats and humans, particularly during the transition from the adaptive to the nonadaptive phase of right heart failure. Noninvasive techniques such as echocardiography and magnetic resonance imaging have recently been used to evaluate the progression of the pulmonary vascular and cardiac hemodynamics, which are important parameters to monitor the efficacy of drug treatment over time. From a pharmacological perspective, most of the compounds approved clinically for the treatment of PAH are efficacious in Su/Hx rats. Several compounds that show efficacy in Su/Hx rats have advanced into phase II/phase III studies in humans with positive results. Results from these drug trials, if successful, will provide additional treatment options for patients with PAH and will also further validate the excellent translation that currently exists between Su/Hx rats and the human PAH condition.

Evaluating Riociguat in the Treatment of Pulmonary Arterial Hypertension: A Real-World Perspective

Pulmonary hypertension (PH) is a broad term describing the mean pulmonary artery pressure, as measured by right heart catheterization, exceeds 20mmHg. Pulmonary arterial hypertension (PAH) exists when PH is accompanied by a normal wedge pressure and elevated pulmonary vascular resistance. PAH is typified by dysmorphic and dysfunctional pulmonary arterial vasculature. Attempting to restore the functionality of the pulmonary artery is a hallmark of care to the PAH patient. Riociguat is a powerful stimulator of soluble guanylate cyclase and increases blood flow through the pulmonary arteries by dilating vascular smooth muscle cells. This review examines the pharmacology of riociguat, the fundamental clinical trials applying it to PAH patients, practical aspects when selecting its use, and future directions for its utilization.

Optimization of specific therapy for pulmonary hypertension: the possibilities of riociguat

Pulmonary hypertension (PH) is a severe and often rapidly progressive disease with fatal outcome. Endothelial dysfunction in PH is associated with decreased nitric oxide production. After reviewing the mechanisms of action and the evidence base for specific therapy with phosphodiesterase 5 inhibitors (PDE-5) and soluble guanylate cyclase stimulators, a reseach review on switching from PDE-5 to riociguat is conducted. A potential advantage of riociguat is its independence from endogenous nitric oxide and from the other (besides PDE-5) isoenzymes of phosphodiesterases. The favorable efficacy profile of sildenafil has been proven for the main forms of pulmonary arterial hypertension, of riociguat for the main forms of pulmonary arterial hypertension and chronic thromboembolic PH. The clinical efficacy of replacing PDE-5 with riociguat has been demonstrated in uncontrolled trials and in the randomized controlled study REPLACE. The possibility of therapy optimization by switching from IFDE-5 to riociguat is fixed in the Russian (class and level of evidence B-3) and Eurasian (class and level of evidence IIb-B) clinical guidelines, as well as in the materials of the Cologne Expert Consensus. An additional argument for switching is the lower cost as compared to combination therapy in the Russian Federation. According to the Russian and Eurasian guidelines for PH and the Russian instructions for the use of riociguat, the drug should be taken at least 24 hours after sildenafil discontinuation.

EXPRESS: Switching to riociguat: A potential treatment strategy for the management of CTEPH and PAH

Currently, five classes of drug are approved for the treatment of pulmonary arterial hypertension (PAH): phosphodiesterase 5 inhibitors (PDE5i); endothelin receptor antagonists; prostacyclin analogs; the IP receptor agonist selexipag; and the soluble guanylate cyclase (sGC) stimulator riociguat. For patients with inoperable or persistent/recurrent chronic thromboembolic pulmonary hypertension (CTEPH), riociguat is currently the only approved pharmacotherapy. Despite the development of evidence-based guidelines on appropriate use of specific drugs, in clinical practice patients are often prescribed PAH-targeted therapies off label or at inadequate doses.

PDE5i are the most often prescribed class of drugs as initial therapy, either alone or in combination with other drug classes. However, a proportion of patients receiving PAH therapies do not reach or maintain treatment goals. As PDE5i and riociguat target different molecules in the nitric oxide-sGC-cyclic guanosine monophosphate (NO-sGC-cGMP) signaling pathway, for patients with PAH without an initial or sustained response to PDE5i, there is a biological rationale for switching to riociguat. However, robust data from randomized controlled trials on the safety and efficacy of switching are lacking, as is formal guidance for clinicians. Here we review studies of sequential combination therapy, and trial data and case studies that have investigated switching between PAH-approved therapies, particularly from PDE5i to riociguat in patients with PAH with an insufficient response to PDE5i, and in patients with CTEPH who were receiving off-label treatment. These studies summarize the current evidence and practical real-life experience on the concept of switching treatments.

Methods of Pharmacological Treatment of Chronic Thromboembolic Pulmonary Hypertension Current Approaches to the Patients Management

In this paper we have discussed epidemiology, pathogenesis, and approaches to treatment of chronic thromboembolic pulmonary hypertension (CTEPH). CTEPH is a unique potentially curable form of pulmonary hypertension. The gold standard of CTEPH treatment is pulmonary thromboendarterectomy. However, about 40% of patients with CTEPH are inoperable due to distal surgically inaccessible lesions of the pulmonary vasculature, severe hemodynamic impairments, or other contraindications. In addition, nearly half of patients have persistent or recurrent pulmonary hypertension following surgery. Current guidelines support the use of pharmacotherapy in these patients. In the article we have presented results of main clinical studies of targeted drugs therapy (endothelin receptor antagonists, prostanoids, phosphodiesterase type 5 inhibitors, soluble guanylate cyclase stimulators) of patients with CTEPH. The only drug that has demonstrated robust clinical efficacy in terms of improvment hemodynamic parameters, exercise capacity and patients' quality of life is the stimulator of the soluble guanylate cyclase riociguat. The efficacy and safety of riociguat have been investigated in short-term and long-term studies with follow-up up to 6 years. Results of these studies have constituted the basis forits approval by the regulatory authorities of more than 50 countries for the treatment of inoperable CTEPH and persistent or recurrent CTEPH after pulmonary thromboendarterectomy. In the European Union, USA and many other countries, riociguat is the only pharmacological agent approved for these indications.

Pulmonary thromboendarterectomy is a curative resolution for chronic thromboembolic pulmonary hypertension associated with antiphospholipid syndrome: a retrospective cohort study

Background

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare and life-threatening condition with poor prognosis in patients with antiphospholipid syndrome (APS). Pulmonary thromboendarterectomy (PTE) is the optimal surgical option for CTEPH.

Objectives

This retrospective cohort study aimed to evaluate the efficacy and risk of PTE in patients with APS-associated CTEPH.

Methods

Consecutive patients with APS-associated CTEPH diagnosed between January 2012 and September 2017 at Peking Union Medical College Hospital were retrospectively evaluated. Demographics, clinical manifestations, antiphospholipid antibody (aPL) profiles, and pulmonary arterial hypertension–targeted medications were collected. Deterioration of cardiac function and death were chosen as the endpoints, in order to assess the effect of PTE on short-term and long-term prognoses (evaluated by the change of cardiac function after treatment and cardiac deterioration or death in the follow-up, respectively).

Results

A total of 20 patients with APS-associated CTEPH were enrolled, and eight patients underwent PTE. Chi-square test ( p = 0.01) and Kaplan–Meier curves (log rank test, p = 0.04) showed that there were statistically significant differences in both short-term and long-term prognoses between patients with and without PTE.

Conclusion

These results provide strong evidence that PTE is a curative resolution in patients with APS-associated CTEPH. Following a full specialized and multidisciplinary risk-benefit evaluation to limit the risk of thrombosis or bleeding and to manage possible thrombocytopenia, PTE is at least a temporal curative resolution for CTEPH complicated with APS.

Real-World Switching to Riociguat: Management and Practicalities in Patients with PAH and CTEPH

Purpose

A proportion of patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) do not achieve treatment goals or experience side effects on their current therapy. In such cases, switching patients to a new drug while discontinuing the first may be a viable and appropriate treatment option. CAPTURE was designed to investigate how physicians manage the switching of patients to riociguat in real-world clinical practice. Observations from the study were used to assess whether recommendations in the riociguat prescribing information are reflected in clinical practice.

Methods

CAPTURE was an international, multicenter, uncontrolled, retrospective chart review that collected data from patients with PAH or inoperable or persistent/recurrent CTEPH who switched to riociguat from another pulmonary hypertension (PH)-targeted medical therapy. The primary objective of the study was to understand the procedure undertaken in real-world clinical practice for patients switching to riociguat.

Results

Of 127 patients screened, 125 were enrolled in CAPTURE. The majority of patients switched from a phosphodiesterase type 5 inhibitor (PDE5i) to riociguat and the most common reason for switching was lack of efficacy. Physicians were already using the recommended treatment-free period when switching patients to riociguat from sildenafil, but a slightly longer period than recommended for tadalafil. In line with the contraindication, the majority of patients did not receive riociguat and PDE5i therapy concomitantly. Physicians also followed the recommended dose-adjustment procedure for riociguat.

Conclusion

Switching to riociguat from another PH-targeted therapy may be feasible in real-world clinical practice in the context of the current recommendations.

Electronic supplementary material

The online version of this article (10.1007/s00408-018-0100-3) contains supplementary material, which is available to authorized users.

Treatment Selection in Pulmonary Arterial Hypertension: Phosphodiesterase Type 5 Inhibitors versus Soluble Guanylate Cyclase Stimulator

Pulmonary arterial hypertension is a chronic and life-threatening disease that if left untreated is fatal. Current therapies include stimulating the nitric oxide-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate axis, improving the prostacyclin pathway and inhibiting the endothelin pathway. Phosphodiesterase type 5 inhibitors, such as sildenafil, and the sGC stimulator riociguat are currently used in the treatment of pulmonary arterial hypertension. This article discusses the similarities and differences between phosphodiesterase type 5 inhibitors and sGC stimulator based on pharmacological action and clinical trials, and considers which is better for the treatment of pulmonary arterial hypertension.