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.

Druggability of Coronary Artery Disease Risk Loci

BACKGROUND

Genome-wide association studies have identified multiple loci associated with coronary artery disease and myocardial infarction, but only a few of these loci are current targets for on-market medications. To identify drugs suitable for repurposing and their targets, we created 2 unique pipelines integrating public data on 49 coronary artery disease/myocardial infarction-genome-wide association studies loci, drug-gene interactions, side effects, and chemical interactions.

METHODS

We first used publicly available genome-wide association studies results on all phenotypes to predict relevant side effects, identified drug-gene interactions, and prioritized candidates for repurposing among existing drugs. Second, we prioritized gene product targets by calculating a druggability score to estimate how accessible pockets of coronary artery disease/myocardial infarction-associated gene products are, then used again the genome-wide association studies results to predict side effects, excluded loci with widespread cross-tissue expression to avoid housekeeping and genes involved in vital processes and accordingly ranked the remaining gene products.

RESULTS

These pipelines ultimately led to 3 suggestions for drug repurposing: pentolinium, adenosine triphosphate, and riociguat (to target CHRNB4, ACSS2, and GUCY1A3, respectively); and 3 proteins for drug development: LMOD1 (leiomodin 1), HIP1 (huntingtin-interacting protein 1), and PPP2R3A (protein phosphatase 2, regulatory subunit b-double prime, α). Most current therapies for coronary artery disease/myocardial infarction treatment were also rediscovered.

CONCLUSIONS

Integration of genomic and pharmacological data may prove beneficial for drug repurposing and development, as evidence from our pipelines suggests.

Tetrandrine prevents monocrotaline-induced pulmonary arterial hypertension in rats through regulation of the protein expression of inducible nitric oxide synthase and cyclic guanosine monophosphate-dependent protein kinase type 1

OBJECTIVE

Pulmonary arterial hypertension (PAH) is a fatal disease characterized by a persistent elevation of pulmonary artery pressure and ventricular hypertrophy. Tetrandrine is a bisbenzylisoquinoline alkaloid that can decrease blood pressure, inhibit the proliferation of vascular smooth muscle cells, and block cardiac hypertrophy, but whether it has a therapeutic effect on PAH remains poorly defined. This study was undertaken to investigate the efficacy of tetrandrine on PAH.

METHODS

Forty-eight male Sprague-Dawley rats were randomly and equally divided into four groups. The control group was injected with normal saline; the others were injected with monocrotaline (MCT) to induce PAH, then treated with saline, tetrandrine, and vardenafil, respectively, from day 21 to day 42. On day 43, we measured the mean pulmonary artery pressure under general anesthesia, dissected the rat, and calculated the right ventricular hypertrophy index [right ventricle/(left ventricle plus septum)]. Later we observed the changes in the pulmonary vascular wall; measured the expression of cyclic guanosine monophosphate-dependent protein kinase type 1 and inducible nitric oxide synthase; measured the levels of superoxide dismutase, glutathione, malondialdehyde, and catalase; and then compared the results among groups.

RESULTS

Compared with the MCT group, rats treated with tetrandrine had attenuated mean pulmonary artery pressure (20.48 ± 1.49 vs 30.07 ± 1.51; P < .01) and right ventricular hypertrophy index (49.19 ± 2.45 vs 68.50 ± 1.95; P < .01), inhibited proliferation of pulmonary artery smooth muscle cells, and improved endothelial function. Tetrandrine also upregulated the expression of protein kinase type 1 (90.86 ± 1.95 vs 67.34 ± 1.50; P < .01); downregulated the expression of inducible nitric oxide synthase (74.76 ± 1.48 vs 80.19 ± 0.28; P < .01); increased levels of superoxide dismutase (245.54 ± 12.98 vs 166.16 ± 21.42; P < .01), glutathione (0.699 ± 0.032 vs 0.514 ± 0.056; P < .01), and catalase (32.13 ± 2.33 vs 27.19 ± 2.72; P < .01); and decreased malondialdehyde (1.027 ± 0.039 vs 1.462 ± 0.055; P < .01).

CONCLUSIONS

Tetrandrine alleviated MCT-induced PAH through regulation of nitric oxide signaling pathway and antioxidant and antiproliferation effects.

Treatment of patients with chronic thrombo embolic pulmonary hypertension: focus on riociguat

Chronic thromboembolic pulmonary hypertension (CTEPH) is a disease of the pulmonary vascular bed that is characterized by elevations in the mean pulmonary artery pressure in the setting of perfusion defects on ventilation–perfusion scan, and subsequently confirmed by pulmonary angiography. CTEPH, or World Health Organization (WHO) group 4 pulmonary hypertension, is a result of unresolved thromboembolic obstruction in the pulmonary arteries. Pulmonary endarterectomy (PEA) is the treatment of choice for CTEPH as it is a potentially curative therapy. However, up to one-third of patients are not candidates for the surgery, either due to distal and inaccessible nature of the lesions or comorbid conditions. Due to remodeling that occurs in nonobstructed pulmonary vessels, a portion of patients who have undergone PEA have residual CTEPH after the procedure, attributable to high shear stress prior to PEA. This phenomenon has led to the understanding of a so-called “two-compartment model” of CTEPH, opening the door to pharmacologic treatment strategies. In 2013, riociguat, a soluble guanylate cyclase stimulator, was approved in the US and Europe for the treatment of inoperable or persistent/recurrent CTEPH. This article reviews the current management of CTEPH with a focus on riociguat.

The limits of oral therapy in pulmonary arterial hypertension management

Pulmonary arterial hypertension (PAH) is a devastating disease in which remodeling of the small pulmonary arteries leads to a progressive increase in pulmonary vascular resistance and right-sided heart failure. Over the past decade, new treatments for PAH, such as the use of ERAs, PDE-5 inhibitors and prostacyclin analogs, have brought about dramatic improvements in clinical outcomes. Epoprostenol infusion therapy has been shown to improve hemodynamics, functional status, and survival, and it remains the gold standard for treatment of patients with severe PAH. Many agents, approved for PAH are always delivered in pill form. Although oral therapy occupies an important position, it has some drawbacks and limitations in PAH management. For patients in World Health Organization functional class IV and with severe right heart failure, there are few data on the long-term survival of patients treated with oral medications. Further research, exploration, and clinical experience with oral therapy in severe PAH and combination therapy will redefine its position in PAH management.

Unusual Bleeding Due to Riociguat Use in a Patient With Chronic Thromboembolic Pulmonary Hypertension

Riociguat is a new drug prescribed to patients with pulmonary hypertension that reduces the pressure in pulmonary artery by vasodilation. This drug like many other drugs has several side effects, some of which can be serious such as bleeding. Riociguat causes vaginal bleeding by increasing endometrial thickness and blood flow to the endometrium, therefore, should be used with care especially for patients who have history of dysfunctional uterine bleeding. In this case report, we present a 27-year-old female patient with chronic thromboembolic pulmonary hypertension and dysfunctional uterine bleeding presented with severe vaginal bleeding under riociguat treatment.