RAHWAY, N.J., Nov. 18, 2025 — Merck (NYSE: MRK) announced positive topline results from the Phase 2 CADENCE study, demonstrating that WINREVAIR™ (sotatercept-csrk) achieved a statistically significant and clinically meaningful reduction in pulmonary vascular resistance (PVR) in adults with combined post- and precapillary pulmonary hypertension (CpcPH) due to heart failure with preserved ejection fraction (HFpEF). The results represent a major scientific milestone for this difficult-to-treat population and support Merck’s plans to advance the program to Phase 3 development.
Science Significance
The CADENCE trial enrolled 164 adults diagnosed with CpcPH due to HFpEF and randomized them to placebo or WINREVAIR at 0.3 mg/kg or 0.7 mg/kg. At 24 weeks, the study met its primary endpoint, demonstrating significant and clinically meaningful improvements in PVR, a key hemodynamic measurement reflecting the resistance blood encounters within the pulmonary vasculature. A reduction in PVR is scientifically important because it signals improved cardiovascular and pulmonary efficiency, potentially leading to better functional outcomes in future trials. PVR is often used as an early mechanistic indicator of therapeutic activity in pulmonary hypertension research; therefore, these results reinforce the biological rationale behind WINREVAIR’s mechanism of action. Notably, the safety profile observed in CADENCE was consistent with previously documented WINREVAIR data, including known risks related to hemoglobin elevation, thrombocytopenia, and bleeding. This alignment strengthens Merck’s scientific justification for progression to larger, confirmatory trials.
Regulatory Significance
From a regulatory development standpoint, CADENCE provides essential proof-of-concept data needed to justify Phase 3 advancement for a new indication. Since WINREVAIR is already FDA-approved and approved in over 50 countries for PAH (WHO Group 1), regulators will examine whether this new dataset supports expanding therapeutic use. Regulators will closely evaluate PVR reduction as a surrogate indicator of likely clinical benefit, as well as secondary measures assessing exercise capacity, echocardiographic changes, biomarkers, and clinical symptoms. The regulatory pathway for CpcPH due to HFpEF is complex due to the heterogenous nature of Group 2 pulmonary hypertension, but CADENCE offers foundational data needed for subsequent global submissions. Merck intends to present full CADENCE results at an upcoming scientific congress, strengthening transparency and regulatory dialogue as the company prepares its Phase 3 strategy.
Business Significance
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WINREVAIR is strategically positioned as one of Merck’s leading cardiopulmonary assets, developed in collaboration with Bristol Myers Squibb. The positive Phase 2 results open new opportunities for therapeutic expansion and significantly enhance the commercial potential of the activin signaling inhibitor platform. If WINREVAIR successfully expands into CpcPH due to HFpEF, it could address a major unmet medical need in a large and growing global patient population, particularly given increasing HFpEF prevalence in aging societies. This could translate into a substantial commercial expansion beyond PAH—an already established multibillion-dollar market. The results also reinforce Merck’s long-term R&D strategy, diversifying the company’s cardiovascular pipeline and strengthening its competitive position against emerging PH-focused therapeutics under development by other global biopharmaceutical companies.
Patients’ Significance
Patients with CpcPH due to HFpEF typically experience limited treatment options, reduced quality of life, and heightened risk of hospitalization and premature mortality. Existing therapies primarily target underlying heart failure or symptom management and do not directly address pulmonary vascular abnormalities. WINREVAIR’s demonstrated ability to improve pulmonary vascular resistance offers hope for a first-in-class treatment specifically addressing mechanisms that drive disease progression. For many patients, even modest improvements in pulmonary hemodynamics may translate into enhanced exercise capacity, less breathlessness, and improved day-to-day functioning. The potential approval of WINREVAIR for CpcPH would mark a landmark shift in care, providing patients and clinicians with a targeted therapeutic option where none currently exist.
Policy Significance
As heart failure and associated cardiopulmonary conditions continue to rise globally, health systems face increasing demand for effective, sustainable treatments. A therapy that improves pulmonary hemodynamics and potentially reduces hospitalization risks aligns with public-health priorities focused on reducing long-term cardiopulmonary burden. Policy implications include Potential reduction in healthcare utilization for advanced HFpEF, Support for reimbursement frameworks prioritizing mechanism-validated therapies. Reinforcement of global health strategies targeting chronic cardiovascular disease, Improvement of diagnostic awareness around CpcPH, an often-underrecognized condition. If WINREVAIR progresses successfully, it may influence future clinical guidelines related to pulmonary hypertension associated with HFpEF.
Transaction Highlights
In the Phase 2 CADENCE study, WINREVAIR produced a statistically significant and clinically meaningful reduction in pulmonary vascular resistance at 24 weeks, establishing pharmacological activity in a new and underserved patient population. The safety profile observed was broadly consistent with prior clinical data, and Merck announced plans to present full results at a future scientific congress. The company confirmed its intention to advance WINREVAIR into Phase 3 development for CpcPH due to HFpEF. WINREVAIR remains FDA-approved for pulmonary arterial hypertension and is authorized in over 50 countries, positioning it as a globally significant therapy with expanding potential across pulmonary vascular diseases.
Source: Ionis Pharmaceuticals, Inc. Press Release
