Merck Stock Rise as New PAH Drug Winrevair Meets Goal in Another Study

Merck MRK announced that the phase II CADENCE study, which evaluated its newly launched pulmonary arterial hypertension (“PAH”) drug Winrevair, for treating adults with combined post and precapillary pulmonary hypertension (CpcPH) due to heart failure with preserved ejection fraction (HFpEF), met its primary endpoint.

Data from the CADENCE study showed that treatment with Winrevair led to a statistically significant and clinically meaningful reduction in pulmonary vascular resistance (“PVR”) from baseline at 24 weeks versus placebo.

Shares of Merck were up 3.8% following the announcement of the news yesterday.

PVR is a key hemodynamic measurement linked to cardiac and pulmonary blood vessel function. It refers to the resistance that the blood must overcome to flow through the pulmonary circulation, that is, the blood vessels in the lungs.

Merck is planning to present these findings from the CADENCE study at a future scientific conference and begin phase III studies on Winrevair in the given patient population.

Preliminary analysis indicates that the safety outcomes seen in the CADENCE study were generally similar to the known safety profile of Winrevair.

MRK Stock's Performance

Year to date, shares of Merck have lost 2.9% against the industry’s growth of 14.3%.

Winrevair was approved by the FDA to treat PAH, WHO Group 1, in March 2024 based on data from the STELLAR study. The drug was approved for a similar use in the European Union in August 2024.

Recently, the FDA approved an update to the Winrevair product label in the United States based on data from the ZENITH study, which evaluated the drug in patients with PAH, WHO Group 1 functional class (“FC”) III or IV at high risk of mortality.

Following the FDA nod for this expanded indication, Winrevair became the first PAH therapy to have an indication that includes components of the clinical worsening events: hospitalization for PAH, lung transplantation and death.

MRK Pin Hopes on Winrevair Amid Looming Keytruda LOE

Merck’s blockbuster PD-L1 inhibitor, Keytruda, has played a key role in driving its steady revenue growth over the past few years. The drug recorded sales of $23.3 billion in the first nine months of 2025, up 8% year over year.

However, Keytruda intravenous (“IV”) formulation is set to face loss of exclusivity (“LOE”) in 2028. Given the heavy reliance and the upcoming LOE of Keytruda IV, Merck has been looking for ways to diversify its product portfolio, especially by growing the non-oncology business to navigate the potential challenges once the inhibitor loses exclusivity.

Among its new products, Merck is pinning hopes on Winrevair to boost its long-term growth.

Winrevair recorded sales worth $976 million in the first nine months of 2025. The positive data from the CADENCE study are likely to provide a label expansion opportunity for Winrevair in a new patient population.

Given that Winrevair has already witnessed a strong launch so far, a potential label expansion should drive sales in 2026 and beyond, helping Merck build its long-term growth trajectory post the Keytruda LOE period.

Winrevair is also being evaluated in the phase III HYPERION study for recently diagnosed adult patients with PAH, WHO Group 1 FC II or III at intermediate or high risk of disease progression.

MRK's Competition in the PAH Market

However, Winrevair faces stiff competition in the PAH market.

Significant players in the PAH market are United Therapeutics UTHR and Johnson & Johnson JNJ.

United Therapeutics markets four drugs to treat PAH in the United States — Remodulin, Orenitram, Tyvaso and Adcirca. UTHR’s Tyvaso recorded sales of $1.41 billion, while Remodulin and Orenitram generated sales of $398.8 million and $375.7 million, respectively, in the first nine months of 2025.

J&J’s key PAH drugs include Opsumit and Uptravi. JNJ recorded revenues of $3.25 billion from its PAH franchise in the first nine months of 2025.

Merck & Co., Inc. Price

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MRK's Zacks Rank

Merck currently has a Zacks Rank #3 (Hold). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.

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This article originally published on Zacks Investment Research (zacks.com).

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