Riociguat in patients with chronic thromboembolic pulmonary hypertension: results from an early access study

Performance-based outcome measures for assessing physical capacity in patients with pulmonary embolism: A scoping review

INTRODUCTION

Up to 50 % of patients surviving a pulmonary embolism (PE) report persisting shortness of breath, reduced physical capacity and psychological distress. As the PE population is heterogeneous compared to other cardiovascular patient groups, outcome measures for assessing physical capacity traditionally used in cardiac populations may not be reliable for the PE population as a whole. This scoping review aims to 1) map performance-based outcome measures (PBOMs) used for assessing physical capacity in PE research, and 2) to report the psychometric properties of the identified PBOMs in a PE population.

METHODS

The review was conducted according to the Joanna Briggs Institute framework for scoping reviews and reported according to the PRISMA-Extension for Scoping Reviews guideline.

RESULTS

The systematic search of five databases identified 4585 studies, of which 243 studies met the inclusion criteria. Of these, 185 studies focused on a subgroup of patients with chronic thromboembolic pulmonary hypertension. Ten different PBOMs were identified in the included studies. The 6-minute walk test (6MWT) and cardiopulmonary exercise test (CPET) were the most commonly used, followed by the (Modified) Bruce protocol and Incremental Shuttle Walk test. No studies reported psychometric properties of any of the identified PBOMs in a PE population.

CONCLUSIONS

Publication of studies measuring physical capacity within PE populations has increased significantly over the past 5-10 years. Still, not one study was identified, reporting the validity, reliability, or responsiveness for any of the identified PBOMs in a PE population. This should be a priority for future research in the field.

The nitric oxide-soluble guanylate cyclase-cGMP pathway in pulmonary hypertension: from PDE5 to soluble guanylate cyclase

The nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway plays a key role in the pathogenesis of pulmonary hypertension (PH). Targeted treatments include phosphodiesterase type 5 inhibitors (PDE5i) and sGC stimulators. The sGC stimulator riociguat is approved for the treatment of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). sGC stimulators have a dual mechanism of action, enhancing the sGC response to endogenous NO and directly stimulating sGC, independent of NO. This increase in cGMP production via a dual mechanism differs from PDE5i, which protects cGMP from degradation by PDE5, rather than increasing its production. sGC stimulators may therefore have the potential to increase cGMP levels under conditions of NO depletion that could limit the effectiveness of PDE5i. Such differences in mode of action between sGC stimulators and PDE5i could lead to differences in treatment efficacy between the classes. In addition to vascular effects, sGC stimulators have the potential to reduce inflammation, angiogenesis, fibrosis and right ventricular hypertrophy and remodelling. In this review we describe the evolution of treatments targeting the NO-sGC-cGMP pathway, with a focus on PH.

Soluble Guanylate Cyclase Stimulators (Riociguat) in Pulmonary Hypertension: Data from Real-Life Clinical Practice in a 3-Year Follow-Up

BACKGROUND

Pulmonary hypertension (PH) is a rare and complex disease with poor prognosis, which requires lifelong treatment.

OBJECTIVE

To describe 3-year follow-up real-life data on treatment with soluble guanylate cyclase stimulators (Riociguat) of patients with PH, measuring current risk assessment parameters.

METHODS

This study retrospectively collected clinical and epidemiological data of patients with PH of group 1 (pulmonary arterial hypertension) and group 4 (chronic thromboembolic PH). Non-invasive and invasive parameters corresponding to the risk assessment were analyzed at baseline and follow-up. Statistical analyses were performed using the SPSS 18.0 software, and p-values < 0.050 were considered statistically significant.

RESULTS

In total, 41 patients receiving riociguat were included in the study. Of them, 31 had already completed 3 years of treatment and were selected for the following analysis. At baseline, 70.7% of patients were in WHO functional class III or IV. After 3 years of treatment, the WHO functional class significantly improved in all patients. In addition, the median of the 6-minute walk test (6MWT) significantly increased from 394 ± 91 m at baseline to 458 ± 100 m after 3 years of follow-up (p= 0.014). The three-year survival rate was 96.7%.

CONCLUSION

In our real-life cohort, most patients with PH treated with riociguat showed stable or improved risk parameters, especially in the 6MWT, at 3 years of follow-up.

A model for estimating the health economic impact of earlier diagnosis of chronic thromboembolic pulmonary hypertension

Background

Diagnostic delay of chronic thromboembolic pulmonary hypertension (CTEPH) exceeds 1 year, contributing to higher mortality. Health economic consequences of late CTEPH diagnosis are unknown. We aimed to develop a model for quantifying the impact of diagnosing CTEPH earlier on survival, quality-adjusted life-years (QALYs) and healthcare costs.

Material and methods

A Markov model was developed to estimate lifelong outcomes, depending on the degree of delay. Data on survival and quality of life were obtained from published literature. Hospital costs were assessed from patient records (n=498) at the Amsterdam UMC – VUmc, which is a Dutch CTEPH referral center. Medication costs were based on a mix of standard medication regimens.

Results

For 63-year-old CTEPH patients with a 14-month diagnostic delay of CTEPH (median age and delay of patients in the European CTEPH Registry), lifelong healthcare costs were estimated at EUR 117 100 for a mix of treatment options. In a hypothetical scenario of maximal reduction of current delay, improved survival was estimated at a gain of 3.01 life-years and 2.04 QALYs. The associated cost increase was EUR 44 654, of which 87% was due to prolonged medication use. This accounts for an incremental cost–utility ratio of EUR 21 900/QALY.

Conclusion

Our constructed model based on the Dutch healthcare setting demonstrates a substantial health gain when CTEPH is diagnosed earlier. According to Dutch health economic standards, additional costs remain below the deemed acceptable limit of EUR 50 000/QALY for the particular disease burden. This model can be used for evaluating cost-effectiveness of diagnostic strategies aimed at reducing the diagnostic delay.

This constructed model based on the Dutch healthcare setting can be used for evaluating cost-effectiveness of diagnostic strategies aimed at reducing the diagnostic delay of chronic thromboembolic pulmonary hypertensionhttps://bit.ly/35yXPM3

Soluble GC stimulators and activators: Past, present and future

The discovery of soluble GC (sGC) stimulators and sGC activators provided valuable tools to elucidate NO-sGC signalling and opened novel pharmacological opportunities for cardiovascular indications and beyond. The first-in-class sGC stimulator riociguat was approved for pulmonary hypertension in 2013 and vericiguat very recently for heart failure. sGC stimulators enhance sGC activity independent of NO and also act synergistically with endogenous NO. The sGC activators specifically bind to, and activate, the oxidised haem-free form of sGC. Substantial research efforts improved on the first-generation sGC activators such as cinaciguat, culminating in the discovery of runcaciguat, currently in clinical Phase II trials for chronic kidney disease and diabetic retinopathy. Here, we highlight the discovery and development of sGC stimulators and sGC activators, their unique modes of action, their preclinical characteristics and the clinical studies. In the future, we expect to see more sGC agonists in new indications, reflecting their unique therapeutic potential.

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.

Results of Macitentan in Japanese Patients With Chronic Thromboembolic Pulmonary Hypertension - A Prospective, Multicenter, Open-Label, Single-Arm, Phase 3 Study

Background: Macitentan, an endothelin-receptor antagonist, is approved in Japan for the treatment of pulmonary arterial hypertension (PAH). This study evaluated the use of macitentan for chronic thromboembolic pulmonary hypertension (CTEPH) in Japanese patients. Methods and Results: This open-label single-arm Phase 3 study evaluated the efficacy and safety of oral macitentan 10 mg (once daily) in Japanese CTEPH patients. The study was prematurely discontinued due to the sponsor's decision to not develop macitentan 10 mg further for the indication of CTEPH (unrelated to safety concerns). Of the 9 patients enrolled in the study, 4 completed 24 weeks of treatment. The mean (±SD) ratio of pulmonary vascular resistance (PVR) at Week 16 to baseline was 71.9±34.3%. The mean (±SD) decreases in PVR and the PVR index (PVRI) from baseline to Week 16 were 181.4±243.9 dyn·s/cm5 and 280.6±366.0 dyn·s·m2/cm5, respectively. The mean (±SD) increase in the 6-min walk distance from baseline to Week 24 was 44.3±46.8 m. All treatment-emergent adverse events (TEAEs) were mild or moderate in severity, except for 1 serious TEAE of angioplasty reported in 1/9 patients that was severe in intensity. Conclusions: Definite conclusions regarding the efficacy of macitentan 10 mg in Japanese patients with CTEPH cannot be drawn because of premature study discontinuation. No safety concerns were observed, and the safety profile was consistent with previously reported studies in CTEPH and PAH patients.

Efficacy and safety of riociguat in the treatment of chronic thromboembolic pulmonary arterial hypertension: A meta-analysis

BACKGROUND

Riociguat is a novel soluble guanylate cyclase stimulator, and has been widely used for the treatment of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension (CTEPH). Some studies found that riociguat had better effects on CTEPH and proved to be safe, but the results were not utterly consistent. Therefore, the purpose of this study was to comprehensively evaluate the efficacy and safety of riociguat in the treatment of CTEPH.

METHODS

Randomized controlled trials on riociguat for the treatment of CTEPH were searched through such electronic databases as PubMed, Embase, Cochrane Library, Web of Science, China national knowledge internet, and Wanfang. The outcomes included exercise capacity, pulmonary hemodynamics, and side effects. The fixed-effects or random-effects models were used to analyze the pooled data, and heterogeneity was assessed by the I2 test.

RESULTS

Four studies involving 520 patients were included in this meta-analysis. Compared with the placebo group, riociguat significantly improved the hemodynamic indexes and increased 6-min walking distance (P < .0001, standardized mean difference (SMD) = -0.24, 95%CI -0.35 to -0.12; P < .00001, SMD = 0.52, 95%CI 0.33 to 0.71), and decreased the Borg dyspnea score (P = .002, SMD = -0.31, 95%CI -0.51 to -0.12). In addition, riociguat could also significantly reduce the living with pulmonary hypertension scores and increase the EQ-5D scores (P = .01, SMD=-0.23, 95%CI -0.42 to -0.05; P < .00001, SMD = 0.47, 95%CI 0.27 to 0.66), but there was no significant difference in the change level of N-terminal pro-hormone B-type natriuretic peptide in patients with riociguat (P = .20, SMD = -0.24, 95%CI -0.61 to -0.13). The common adverse events of riociguat were dyspepsia and peripheral edema, and no other serious adverse reactions were observed.

CONCLUSIONS

We confirmed that riociguat had better therapeutic effects in improving the hemodynamic parameters and exercise capacity in patients with CTEPH without inducing serious adverse events. This will provide a reasonable medication regimen for the treatment of CTEPH.

Riociguat: Clinical research and evolving role in therapy

Riociguat is a first-in-class soluble guanylate cyclase stimulator, approved for the treatment of adults with pulmonary arterial hypertension (PAH), inoperable chronic thromboembolic pulmonary hypertension (CTEPH), or persistent or recurrent CTEPH after pulmonary endarterectomy. Approval was based on the results of the phase III PATENT-1 (PAH) and CHEST-1 (CTEPH) studies, with significant improvements in the primary endpoint of 6-minute walk distance vs placebo of +36 m and +46 m, respectively, as well as improvements in secondary endpoints such as pulmonary vascular resistance and World Health Organization functional class. Riociguat acts as a stimulator of cyclic guanosine monophosphate synthesis rather than as an inhibitor of cGMP metabolism. As with other approved therapies for PAH, riociguat has antifibrotic, antiproliferative and anti-inflammatory effects, in addition to vasodilatory properties. This has led to further clinical studies in patients who do not achieve a satisfactory clinical response with phosphodiesterase type-5 inhibitors. Riociguat has also been evaluated in patients with World Health Organization group 2 and 3 pulmonary hypertension, and other conditions including diffuse cutaneous systemic sclerosis, Raynaud's phenomenon and cystic fibrosis. This review evaluates the results of the original clinical trials of riociguat for the treatment of PAH and CTEPH, and summarises the body of work that has examined the safety and efficacy of riociguat for the treatment of other types of pulmonary hypertension.

Riociguat treatment in patients with chronic thromboembolic pulmonary hypertension: Final safety data from the EXPERT registry

OBJECTIVE

The soluble guanylate cyclase stimulator riociguat is approved for the treatment of adult patients with pulmonary arterial hypertension (PAH) and inoperable or persistent/recurrent chronic thromboembolic pulmonary hypertension (CTEPH) following Phase 3 randomized trials. The EXPosurE Registry RiociguaT in patients with pulmonary hypertension (EXPERT) study was designed to monitor the long-term safety of riociguat in clinical practice.

METHODS

EXPERT was an international, multicenter, prospective, uncontrolled, non-interventional cohort study of patients treated with riociguat. Patients were followed for at least 1 year and up to 4 years from enrollment or until 30 days after stopping riociguat treatment. Primary safety outcomes were adverse events (AEs) and serious adverse events (SAEs) coded using Medical Dictionary for Regulatory Activities preferred terms and System Organ Classes version 21.0, collected during routine clinic visits and collated via case report forms.

RESULTS

In total, 956 patients with CTEPH were included in the analysis. The most common AEs in these patients were peripheral edema/edema (11.7%), dizziness (7.5%), right ventricular (RV)/cardiac failure (7.7%), and pneumonia (5.0%). The most common SAEs were RV/cardiac failure (7.4%), pneumonia (4.1%), dyspnea (3.6%), and syncope (2.5%). Exposure-adjusted rates of hemoptysis/pulmonary hemorrhage and hypotension were low and comparable to those in the long-term extension study of riociguat (Chronic Thromboembolic Pulmonary Hypertension Soluble Guanylate Cyclase-Stimulator Trial [CHEST-2]).

CONCLUSION

Data from EXPERT show that in patients with CTEPH, the safety of riociguat in routine practice was consistent with the known safety profile of the drug, and no new safety concerns were identified.

[The achievements of the modern specific therapy of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: focus on the stimulator of soluble guanylate cyclase riociguat]

Currently, treatment of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) is focused on three signaling pathways: the NO pathway, the endothelin pathway, and the prostacyclin pathway. Riociguat is the only representative of stimulators of the soluble guanylate cyclase (sGC) class that is approved for the treatment of PAH and inoperable and persistent/recurrent CTEPH. The review presents data from clinical trials showing a positive effect of riociguat on the functional and hemodynamic profile of patients with PAH and CTEPH. In recent years there has been much discussion about the possibility of optimizing therapy by switching to drugs that affect a single pathogenesis target. Thus, sGC stimulants have obvious advantages over phosphodiesterase type 5 (PDE-5) inhibitors, including the ability of riociguat to exert pharmacological effects (due to a NO-independent mechanism of action) even in conditions of reduced NO production. Switching from PDE-5 to riociguat may be safe and appropriate, according to clinical trials presented in the review. In accordance with the guidelines for the diagnosis and treatment of pulmonary hypertension of the Eurasian Association of cardiologists from 2019, this strategy is approved when PDE5 therapy is ineffective in patients with PAH FC III (WHO).

Riociguat in the Treatment of Chronic Thromboembolic Pulmonary Hypertension: An Evidence-Based Review of Its Place in Therapy

Chronic thromboembolic pulmonary hypertension (CTEPH) is classified as group-4 pulmonary hypertension caused by organized thrombi in pulmonary arteries and vasculopathy in nonoccluded areas leading to right heart failure and death. In addition to chronic anticoagulation therapy, each patient with CTEPH should receive treatment assessment starting with evaluation for pulmonary endarterectomy (PEA), which is the guideline recommended treatment. There is increasing experience with balloon pulmonary angioplasty (BPA) for inoperable patients; this option, like PEA, is reserved for specialized centers with expertise in this treatment method. Inoperable patients are candidates for targeted drug therapy. Riociguat remains the only approved medical therapy for CTEPH patients deemed inoperable or with persistent pulmonary hypertension after PEA. The role of riociguat therapy preoperatively or in tandem with BPA is currently under investigation. The purpose of this review is to evaluate the safety and efficacy of riociguat in the treatment of CTEPH.

Treatment of pulmonary hypertension with riociguat: a review of current evidence and future perspectives

INTRODUCTION

Pulmonary arterial hypertension (PAH) is still a chronic disorder characterized by high morbidity and mortality. Chronic thromboembolic pulmonary hypertension (CTEPH) is another form of pulmonary hypertension (PH) for which pulmonary endarterectomy (PEA) is the treatment of choice. However, not all patients are operable, while PH is often recurrent or persistent. Thus, for both disorders novel treatment options are urgently needed.

AREAS COVERED

This review describes the mechanism of action of riociguat, a soluble guanylate cyclase (sGC) stimulator, with a dual mode of action. The most relevant publications are presented regarding the efficacy of riociguat in PAH and CTEPH, and also data regarding its potential effect on other forms of PH.

EXPERT OPINION

Riociguat is a first-in-class drug approved for the treatment of PAH as a monotherapy or added to endothelin-receptor antagonists as a sequential combination therapy, and for the treatment of inoperable CTEPH or persistent/recurrent PH after PEA. As it can stimulate sGC independently of NO, it could be beneficial in PAH patients with inadequate response to phosphodiesterase 5 inhibitors (PDE5i). Future studies are needed to evaluate whether drug switching is beneficial in PAH and which baseline markers could guide the optimal initial treatment selection.

Advances in targeted therapy for chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by unresolved thrombi in the pulmonary arteries and microvasculopathy in nonoccluded areas. If left untreated, progressive pulmonary hypertension will induce right heart failure and, finally, death. Currently, pulmonary endarterectomy (PEA) remains the only method that has the potential to cure CTEPH. Unfortunately, up to 40% of patients are ineligible for this procedure for various reasons. In recent years, refined balloon pulmonary angioplasty (BPA) has become an alternative option for inoperable CTEPH patients, and it may be another curative treatment in the future, particularly in combination with prior PEA. Nevertheless, 23% of patients still suffer from persistent PH after BPA. Given that CTEPH shares many similarities with idiopathic pulmonary arterial hypertension (PAH), targeted drugs developed for PAH are also attractive options for CTEPH, especially for inoperable or persistent/recurrent CTEPH patients. To date, riociguat, macitentan, and subcutaneous treprostinil are the only drugs proven by randomized control trials to be capable of improving the exercise capacity (6-min walking distance) of CTEPH patients. In this review, we summarize the achievements and unresolved problems of PAH-targeted therapy for CTEPH over the last decade.

Population pharmacokinetics of riociguat and its metabolite in patients with chronic thromboembolic pulmonary hypertension from routine clinical practice

Pharmacokinetic data for riociguat in patients with chronic thromboembolic pulmonary hypertension (CTEPH) have previously been reported from randomized clinical trials, which may not fully reflect the population encountered in routine practice. The aim of the current study was to characterize the pharmacokinetic of riociguat and its metabolite M1 in the patients from routine clinical practice. A population pharmacokinetic model was developed in NONMEM 7.3, based on riociguat and its metabolite plasma concentrations from 49 patients with CTEPH. One sample with riociguat and M1 concentrations was available from each patient obtained at different time points after last dose. Age, bodyweight, sex, smoking status, concomitant medications, kidney and liver function markers were tested as potential covariates of pharmacokinetic of riociguat and its metabolite. Riociguat and M1 disposition was best described with one-compartment models. Apparent volume of distribution (Vd/F) for riociguat and M1 were assumed to be the same. Total bilirubin and creatinine clearance were the most predictive covariates for apparent riociguat metabolic clearance to M1 (CL_f,M1/F) and for apparent riociguat clearance through remaining pathways (CL_e,r/F), respectively. CL_f,M1/F, CL_e,r/F, Vd/F of riociguat and M1, and clearance of M1 (CL_e,M1/F) for a typical individual with 70 mL/min creatinine clearance and 0.69 mg/dL total bilirubin were 0.665 L/h (relative standard error = 17%)), 0.66 (18%) L/h, 3.63 (15%) L and 1.47 (19%) L/h, respectively. Upon visual identification of six outlying individuals, an absorption lag-time of 2.95 (6%) h was estimated for these patients. In conclusion, the only clinical characteristics related to riociguat exposure in patients with CTEPH from routine clinical practice are total bilirubin and creatinine clearance. This confirms the findings of the previous population pharmacokinetic studies based on data from randomized clinical trials.

Balloon pulmonary angioplasty vs riociguat in patients with inoperable chronic thromboembolic pulmonary hypertension: A systematic review and meta-analysis

Backgrounds

No previous meta‐analyses have compared the efficacy and safety of BPA with riociguat therapy in inoperable CTEPH patients.

Methods

Relevant published studies were searched in the PubMed, Embase and ClinicalTrial.gov databases.

Results

Twenty‐three clinical trials including 1454 patients (631 underwent BPA; 823 underwent riociguat therapy) were analyzed. BPA was associated with a greater improvement in RAP (mean difference (MD) = −3.53 mmHg, 95% CI: [−4.85, −2.21] vs MD = −1.05 mmHg, 95% CI: [−1.82, −0.29]); mPAP (MD = −15.02 mmHg, 95% CI: [−17.32, −12.71] vs MD = −4.19 mmHg, 95% CI: [−5.58, −2.80]); PVR (standard MD = −1.32 woods, 95% CI: [−1.57, −1.08] vs standard MD = −0.65 woods, 95% CI: [−0.79, −0.50]); NYHA functional class (RR = 6.78, 95% CI: [3.14, 14.64] vs RR = 1.49, 95% CI: [1.07, 2.07]); and 6MWD (MD = 71.66 m, 95% CI: [58.34, 84.99] vs MD = 45.25 m, 95% CI: [36.51, 53.99]) than riociguat treatment. However, the increase in CO was greater with riociguat (MD = 0.78 L/min, 95% CI: [0.61, 0.96]) than with BPA (MD = 0.33 L/min, 95% CI: [0.06, 0.59]). No significant difference in cardiac index (CI) was found between BPA (MD = 0.40 L/min/m², 95% CI: [0.21, 0.58]) and riociguat (MD = 0.40 L/min/m², 95% CI: [0.26, 0.54]). The most common complications of BPA were pulmonary injury (0.3%‐5.6%) and pulmonary edema (0.8%‐28.6%). The most common adverse events of riociguat were headache, dizziness, hypotension and nasopharyngitis.

Conclusions

Our meta‐analysis indicates that BPA might be associated with greater improvements in exercise tolerance and pulmonary hemodynamics except for cardiac output and cardiac index than riociguat therapy. However, both of them were well tolerated.

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.

Right ventricular size and function under riociguat in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension (the RIVER study)

BACKGROUND

Riociguat is a soluble guanylate cyclase stimulator approved for pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTPEH). The objective of this study was to evaluate right heart size and function assessed by echocardiography during long term treatment with riociguat.

METHODS

Patients who started riociguat treatment (1.0-2.5 mg tid) within the trials phase II, PATENT, PATENTplus, EAS, CHEST and continued treatment for 3-12 months were included in this study. Echocardiography was analysed off-line at baseline, after 3, 6 and 12 months by investigators who were blinded to clinical data. Last and baseline observation carried forward method (LOCF, BOCF) were performed as sensitivity analysis.

RESULTS

Seventy-one patients (45% PAH, 55% CTEPH; 53.5% female; 60 ± 13 years, mean pulmonary arterial pressure 46 ± 10 mmHg, mean PVR 700 ± 282dynes·sec·cm-5) were included. After 6 months, RA and RV area, RV thickness tricuspid regurgitation velocity showed a significant reduction. After 12 months, patients receiving riociguat therapy showed a significant reduction in right atrial (- 2.6 ± 4.4 cm2, 95% CI -3.84, - 1.33; p < 0.001, n = 49) and right ventricular (RV) area (- 3.5 ± 5.2 cm2, 95% CI -5.1, - 1.9; p < 0.001; n = 44), RV thickness (- 0.76 ± 2.2 mm, 95% CI -1.55, 0.03; n = 32), and a significant increase in TAPSE (2.95 ± 4.78 mm, 95% CI 1.52, 4.39; n = 45) and RV fractional area change (8.12 ± 8.87 mm, 95% CI 4.61, 11.62; n = 27). Both LOCF and BOCF showed similar results but lower effect sizes.

CONCLUSION

Patients under long-term treatment with riociguat show significantly reduced right heart size and improved RV function in PAH and CTEPH. Further controlled prospective studies are needed to confirm these results.

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.

Influence of riociguat treatment on pulmonary arterial hypertension : A meta-analysis of randomized controlled trials

BACKGROUND

Riociguat treatment might be beneficial for pulmonary arterial hypertension. However, the results of studies to date are controversial. We conducted a systematic review and meta-analysis to explore the influence of riociguat treatment on pulmonary arterial hypertension.

METHODS

The PubMed, Embase, Web of science, EBSCO, and Cochrane Library databases were systematically searched. Randomized controlled trials (RCTs) assessing the effect of riociguat treatment on pulmonary arterial hypertension were included. Two investigators independently searched articles, extracted data, and assessed the quality of included studies. This meta-analysis was performed using the random effects model.

RESULTS

Seven RCTs were included in the meta-analysis. Compared with a control intervention in pulmonary arterial hypertension, riociguat treatment was able to substantially improve results of the six-minute walking distance (6-MWD; standardized mean difference [SMD] = 0.53; 95% CI = 0.36-0.69; p < 0.00001), EQ-5D score (SMD = 0.35; 95% CI = 0.15-0.54; p = 0.0005), and cardiac index (SMD = 0.94; 95% CI = 0.59-1.29; p < 0.00001). The Living With Pulmonary Hypertension (LPH) score (SMD = -0.33; 95% CI = -0.50--0.17; p < 0.0001) and pulmonary vascular resistance (PVR; SMD = -0.88; 95% CI = -1.05--0.70; p < 0.00001) were significantly reduced after riociguat treatment. There was no increase in adverse events with riociguat treatment compared with the control intervention (RR = 1.04; 95% CI = 0.98-1.09; p = 0.19).

CONCLUSION

Riociguat treatment for pulmonary arterial hypertension led to a significant increase in the 6‑MWD, EQ-5D score, and cardiac index, as well as a decrease in LPH score and PVR.

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.