Vericiguat for the Inhibition of Calcific Aortic Valve Stenosis Progression

BACKGROUND AND UNMET NEED Calcific aortic valve stenosis (CAVS) is the most common valvular heart disease worldwide and a leading cause of heart failure, valve replacement, and cardiovascular death in older adults. In Western populations, the prevalence of CAVS reaches 1-2% among individuals aged ≥65 years and approximately 12% in those aged ≥75 years. In China, prevalence is rising sharply as the population ages. Once the aortic valve peak velocity exceeds 2.5 m/s, the disease typically progresses to severe stenosis within a decade. Among patients with symptomatic severe aortic stenosis who do not undergo intervention, two-year mortality approaches 50%.

Aortic valve replacement-either surgical (SAVR) or transcatheter (TAVI)-is currently the only effective treatment for severe CAVS. However, valve replacement carries substantial procedural risks (stroke, conduction block, paravalvular leak, bleeding, infection) and imposes a heavy economic burden. There is therefore an urgent clinical need for a pharmacological intervention that can slow CAVS progression at the mild-to-moderate stage and thereby reduce the proportion of patients who progress to severe stenosis requiring valve replacement.

Over the past two decades, numerous randomized controlled trials have tested pharmacological strategies for slowing CAVS progression, including intensive statin therapy (SALTIRE, TASS, ASTRONOMER), anti-osteoporotic agents (SALTIRE-2: denosumab and alendronate), vitamin K2 plus vitamin D supplementation, and DPP-4 inhibitors (evogliptin). All have yielded negative results. Recent evidence has reframed CAVS as an active fibro-calcific disease driven by valvular interstitial cell (VIC) osteogenic differentiation, endothelial dysfunction, and inflammatory signaling, rather than a passive degenerative process. The consistent failure of prior trials highlights the need for mechanistically novel therapeutic targets.

RATIONALE FOR TARGETING THE NO-sGC-cGMP PATHWAY Cyclic guanosine monophosphate (cGMP) is a critical second messenger in cardiovascular homeostasis, synthesized from GTP by guanylate cyclases. Soluble guanylate cyclase (sGC)-the principal receptor for nitric oxide (NO)-is widely expressed in valvular endothelial cells and VICs. cGMP activates protein kinase G (PKG), which exerts multiple protective effects including suppression of VIC osteogenic differentiation, preservation of mitochondrial function, and attenuation of oxidative stress.

In calcified aortic valve tissue, the NO-sGC-cGMP signaling axis is markedly impaired despite compensatory upregulation of sGC subunits. The key mechanism involves localized oxidative stress that converts sGC from its active (reduced, heme-containing) form to an oxidized or heme-free form that is insensitive to endogenous NO, thereby limiting cGMP production. Our group has further demonstrated that serum cGMP concentrations are significantly reduced in patients with CAVS and correlate inversely with CT-derived aortic valve calcium (AVC) scores and echocardiographic mean pressure gradients, supporting cGMP-PKG pathway downregulation as a hallmark of CAVS progression.

sGC stimulators are a novel drug class that can restore this pathway through a dual mechanism: (1) direct, NO-independent stimulation of sGC to generate cGMP, and (2) enhancement of sGC sensitivity to residual endogenous NO. This property allows sGC stimulators to function effectively in the oxidative valvular microenvironment, overcoming the limitation of conventional NO donors.

PRECLINICAL EVIDENCE FOR VERICIGUAT IN CAVS

Vericiguat is a novel oral sGC stimulator with a long half-life (\~22 hours) enabling once-daily dosing and favorable pharmacokinetics. Our research group has systematically characterized its anti-calcification effects across three experimental levels:

1. Cellular level: In human VICs cultured under calcifying conditions, vericiguat (500 nM and 1 μM) significantly reduced osteogenic markers, including alkaline phosphatase (ALP) activity and RUNX2 protein expression (P\<0.01). Among multiple cGMP agonists tested (BNP, sildenafil, vericiguat), vericiguat exhibited the most potent anti-calcification effect.
2. Tissue level: In ex vivo human aortic valve tissue cultured under pro-calcific conditions, vericiguat (1 μM) intervention for 21 days markedly reduced calcium deposition as assessed by Alizarin Red and von Kossa staining.
3. Animal level: In two established mouse models of CAVD-LDLR-/- mice fed a high-fat diet and a wire-injury aortic valve model-vericiguat (3-10 mg/kg/day) significantly reduced leaflet calcification and thickening and improved hemodynamic parameters (peak transvalvular velocity, aortic valve area). The high-dose group (10 mg/kg/day) showed the greatest efficacy. Mechanistically, integrated transcriptomic, proteomic, and phosphoproteomic analyses revealed that PKGI phosphorylates ULK1 at Ser556, enhancing autophagic flux, preserving mitochondrial function, and reducing oxidative stress, thereby suppressing VIC osteogenic differentiation. Prkg1+/- heterozygous knockout mouse studies confirmed PKGI as the critical mediator of vericiguat's anti-calcification effect.

CLINICAL EVIDENCE SUPPORTING sGC STIMULATION IN CAVS Clinical validation of sGC pathway targeting in CAVS comes from an independent study of ataciguat, another sGC activator. In human ex vivo valve tissue, ataciguat enhanced sGC signaling and reduced BMP2 signaling. In a murine CAVS model, ataciguat significantly reduced aortic valve calcification. In its phase II randomized controlled trial, ataciguat slowed AVC score progression by approximately 70% over 6 months (P=0.051), providing the first human evidence that sGC pathway activation may exert disease-modifying effects in CAVS.

In the VICTORIA trial (N=5,050), vericiguat significantly reduced the composite of cardiovascular death and heart failure hospitalization (HR 0.90, P=0.019) in patients with heart failure with reduced ejection fraction without increasing symptomatic hypotension or syncope. This safety profile is critical for CAVS patients, in whom hypotension could exacerbate transvalvular gradients and impair coronary perfusion.

STUDY DESIGN This is a multicenter, randomized, double-blind, placebo-controlled trial enrolling approximately 238 participants with mild-to-moderate CAVS across roughly 19 hospitals in China. Participants are randomized 1:1 to vericiguat or matching placebo, stratified by baseline AVC score (200-600 AU vs. ≥600 AU), and followed for 24 months. Both arms receive guideline-directed background therapy for comorbidities throughout the study. The double-dummy design-in which placebo tablets match the three dose strengths of vericiguat (2.5 mg, 5 mg, 10 mg) in size, shape, color, and texture-ensures that participants, treating investigators, imaging personnel, and outcome assessors remain blinded throughout.

The primary endpoint is the change in log-transformed aortic valve calcium (AVC) score from baseline to 24 months. AVC progression was selected as the primary efficacy measure for three reasons. First, aortic valve calcification is the core pathological driver of CAVS, and calcium accumulation closely parallels hemodynamic deterioration across the disease spectrum; quantifying calcification progression therefore assesses the most upstream and potentially reversible driver of disease. Second, CT-based AVC measurement demonstrates markedly superior reproducibility compared with echocardiographic parameters. A hierarchical composite endpoint-comprising all-cause death, aortic valve-related clinical events, and AVC change, analyzed using the Win Ratio method-serves as a secondary endpoint to capture integrated clinical benefit.

POPULATION The study targets patients aged 35-80 years with mild-to-moderate CAVS. This disease stage represents the optimal window for pharmacological intervention: valve leaflets retain structural plasticity and have not yet undergone irreversible fibro-calcific remodeling, whereas patients with severe stenosis are likely to require valve replacement within a short timeframe and would not benefit from a 24-month drug trial. Key safety-driven exclusions-significant left ventricular dysfunction (LVEF \<50%), advanced heart failure symptoms (NYHA class III-IV), and baseline systolic blood pressure below 120 mmHg-mitigate confounding from concomitant cardiac disease and minimize the risk of drug-related hypotension in a population with pre-existing afterload limitation. Full eligibility criteria are provided in the Eligibility section.

DOSE SELECTION RATIONALE

The dosing regimen mirrors the established titration schedule from the VICTORIA trial: vericiguat 2.5 mg once daily, doubled every 2 weeks to a target maintenance dose of 10 mg once daily. The rationale is as follows:

Phase I data: Across six phase I studies (265 participants), vericiguat was well tolerated at doses up to 10 mg once daily, with plasma cGMP concentrations rising in a dose-dependent manner. At 15 mg, dose-limiting pharmacodynamic effects (orthostatic reactions and syncope) were observed, establishing 10 mg as the safe upper limit. The half-life of approximately 22 hours supports once-daily dosing.

Phase II data: In the SOCRATES-REDUCED trial, vericiguat dose-dependently reduced NT-proBNP with the 10 mg target dose showing the most favorable efficacy signal while maintaining acceptable tolerability.

Phase III data: The VICTORIA trial confirmed that the 2.5→5→10 mg titration schedule achieved both efficacy and safety in a large heart failure population, importantly without excess symptomatic hypotension or syncope.

Preclinical dose-response: In LDLR-/- mice fed a high-fat diet, vericiguat at 10 mg/kg/day reduced peak transvalvular velocity by approximately 40% (P=0.0002), leaflet calcification area by approximately 50% (P\<0.0001), leaflet thickness from approximately 150 μm to 80 μm (P=0.0088), and RUNX2 expression by approximately 65% (P\<0.0001), with the 10 mg/kg/day dose consistently outperforming 3 mg/kg/day.

SAFETY MONITORING AND RISK MITIGATION The primary anticipated risk of vericiguat in the CAVS population is hypotension, given its vasodilatory mechanism. Risk mitigation includes exclusion of participants with baseline SBP \<120 mmHg or history of symptomatic hypotension; a conservative stepwise dose-titration schedule (2.5 mg starting dose, doubled every 2 weeks) with protocol-defined dose-reduction rules when SBP falls below 90 mmHg; investigator discretion to reduce concomitant non-evidence-based vasodilatory medications before reducing study drug; and continuous blood pressure monitoring at all scheduled and unscheduled visits. An independent Data and Safety Monitoring Board (DSMB) conducts periodic reviews of unblinded safety data. Participants who permanently discontinue study drug are followed for the full 24-month study duration to permit intention-to-treat analysis.