Practical management of riociguat in patients with pulmonary arterial hypertension

Identification of new multi-substituted 1H-pyrazolo[3,4-c]pyridin-7(6H)-ones as soluble guanylyl cyclase (sGC) stimulators with vasoprotective and anti-inflammatory activities

Herein, we describe the rational design, synthesis and in vitro functional characterization of new heme-dependent, direct soluble guanylyl cyclase (sGC) agonists. These new compounds bear a 1H-pyrazolo[3,4-c]pyridin-7(6H)-one skeleton, modified to enable efficient sGC binding and stimulation. To gain insights into structure-activity relationships, the N6-alkylation of the skeleton was explored, while a pyrimidine ring, substituted with various C5'-polar groups, was installed at position C3. Among the newly synthesized 1H-pyrazolo[3,4-c]pyridin-7(6H)-ones, derivatives 14b, 15b and 16a display characteristic features of sGC "stimulators" in A7r5 vascular smooth muscle cells in vitro. They strongly synergize with the NO donor, sodium nitroprusside (SNP) in inducing cGMP generation in a manner that requires the presence of a reduced heme moiety associated with sGC, and elevate the cGMP-responsive phosphorylation of the protein VASP at Ser239. In line with their sGC stimulating capacity, docking calculations of derivatives 16a, 15(a-c) on a cryo-EM structure of human sGC (hsGC) in an ΝΟ-activated state indicated the implication of 1H-pyrazolo[3,4-c]pyridin-7(6H)-one skeleton in efficient bonding interactions with the recently identified region that binds known sGC stimulators, while the presence of either a N6-H or N6-methyl group pointed to enhanced binding affinity. Moreover, the in vitro functional effects of our newly identified sGC stimulators were compatible with a beneficial role in vascular homeostasis. Specifically, derivative 14b reduced A7r5 cell proliferation, while 16a dampened the expression of adhesion molecules ICAM-1 and P/E-Selectin in Human Umbilical Vein Endothelial Cells (HUVECs), as well as the subsequent adhesion of U937 leukocytes to the HUVECs, triggered by tumor necrosis factor alpha (TNF-α) or interleukin-1 beta (IL-1β). The fact that these compounds elevate cGMP only in the presence of NO may indicate a novel way of interaction with the enzyme and may make them less prone than other direct sGC agonists to induce characteristic hypotension in vivo.

Vericiguat: The Fifth Harmony of Heart Failure with Reduced Ejection Fraction

Heart failure with reduced ejection fraction is a chronic and progressive syndrome that continues to be a substantial financial burden for health systems in Western countries. Despite remarkable advances in pharmacologic and device-based therapy over the last few years, patients with heart failure with reduced ejection fraction have a high residual risk of adverse outcomes, even when treated with optimal guideline-directed medical therapy and in a clinically stable state. Worsening heart failure episodes represent a critical event in the heart failure trajectory, carrying high residual risk at discharge and dismal short- or long-term prognosis. Recently, vericiguat, a soluble guanylate cyclase stimulator, has been proposed as a novel drug whose use is already associated with a reduction in heart failure-related hospitalizations in patients in guideline-directed medical therapy. In this review, we summarized the pathophysiology of the nitric oxide-soluble guanylate cyclase-cyclic guanosine monophosphate cascade in patients with heart failure with reduced ejection fraction, the pharmacology of vericiguat as well as the evidence regarding their use in patients with HFrEF. Finally, tips and tricks for its use in standard clinical practice are provided.

Efficacy of the thromboxane receptor antagonist NTP42 alone, or in combination with sildenafil, in the sugen/hypoxia-induced model of pulmonary arterial hypertension

NTP42 is a novel antagonist of the thromboxane A₂ receptor (TP) in development for the treatment of pulmonary arterial hypertension (PAH). Recent studies demonstrated that NTP42 and TP antagonism have a role in alleviating PAH pathophysiology. However, the efficacy of NTP42 when used in combination with existing PAH therapies has not yet been investigated. Herein, the Sugen 5416/hypoxia (SuHx)-induced PAH model was employed to evaluate the efficacy of NTP42 when used alone or in dual-therapy with Sildenafil, a PAH standard-of-care. PAH was induced in rats by injection of Sugen 5416 and exposure to hypoxia for 21 days. Thereafter, animals were treated orally twice-daily for 28 days with either vehicle, NTP42 (0.05 mg/kg), Sildenafil (50 mg/kg), or NTP42+Sildenafil (0.05 mg/kg + 50 mg/kg, respectively). While Sildenafil or NTP42 mono-therapy led to non-significant reductions in the SuHx-induced rises in mean pulmonary arterial pressure (mPAP) or right ventricular systolic pressure (RSVP), combined use of NTP42+Sildenafil significantly reduced these increases in mPAP and RVSP. Detailed histologic analyses of pulmonary vessel remodelling, right ventricular hypertrophy and fibrosis demonstrated that while NTP42 and Sildenafil in mono-therapy resulted in significant benefits, NTP42+Sildenafil in dual-therapy showed an even greater benefit over either drug used alone. In summary, combined use of NTP42+Sildenafil in dual-therapy confers an even greater benefit in treating or offsetting key aetiologies underlying PAH. These findings corroborate earlier preclinical findings suggesting that, through antagonism of TP signalling, NTP42 attenuates PAH pathophysiology, positioning it as a novel therapeutic for use alone or in combination therapy regimens.

"On Water" Palladium Catalyzed Direct Arylation of 1H-Indazole and 1H-7-Azaindazole

The C3 direct arylation of 1H-indazole and 1H-7-azaindazole has been a significant challenge due to the lack of the reactivity at this position. In this paper, we describe a mild and an efficient synthesis of new series of C3-aryled 1H-indazoles and C3-aryled 1H-7-azaindazoles via a C3 direct arylation using water as solvent. On water, PPh₃ was effective as a ligand along with a lower charge of the catalyst Pd(OAc)₂ (5 mol%) at 100 °C, leading to C3-aryled 1H-indazoles or C3-aryled 1H-7-azaindazoles in moderate to good yields.