Merck & Co. Inc. (MRK) keeps racking up wins for Winrevair, its increasingly important cardiovascular drug. The company announced Tuesday that its Phase 2 CADENCE study hit the mark, showing the drug works for a particularly complex heart condition that affects how blood flows through the lungs.

Here's what happened: CADENCE tested Winrevair (sotatercept-csrk) in adults dealing with combined post- and pre-capillary pulmonary hypertension caused by heart failure with preserved ejection fraction. That's quite a mouthful, but it essentially describes a condition where the heart can't pump efficiently and the blood vessels in the lungs are struggling as a result.

The study met its primary endpoint, demonstrating a statistically significant and clinically meaningful reduction in pulmonary vascular resistance from baseline at 24 weeks compared to placebo. Think of pulmonary vascular resistance as a measure of how hard it is for blood to flow through your lung vessels—lower is better, and Winrevair delivered those lower numbers.

"In this study, Winrevair improved pulmonary vascular resistance, an important hemodynamic measurement related to cardiac and pulmonary blood vessel function that has the potential to translate into improved outcomes for patients with combined post and pre-capillary pulmonary hypertension due to heart failure with preserved ejection fraction," said Dr. Mahesh Patel, vice president of global clinical development at Merck Research Laboratories.

The safety profile looked good too. Based on preliminary assessment, the CADENCE study showed results generally consistent with what researchers already know about Winrevair's safety, which is exactly what you want to see when testing a drug in new patient populations.

Merck isn't wasting time. The company plans to present full results at an upcoming scientific congress and intends to move forward with Phase 3 development, the final major hurdle before potentially seeking regulatory approval for this new indication.

This success builds on Winrevair's momentum. Back in June, Merck announced positive topline results from the Phase 3 HYPERION study, which evaluated Winrevair versus placebo. In that study, the drug—added on top of background therapy within 12 months after initial diagnosis of pulmonary arterial hypertension—demonstrated a statistically significant and clinically meaningful reduction in the risk of clinical worsening events compared to placebo. About 72% of patients in that trial were on double therapy as their background treatment.

Winrevair already has FDA approval as an activin signaling inhibitor for adults with pulmonary arterial hypertension. The approved uses include improving exercise capacity and WHO functional class, plus reducing the risk of clinical worsening events like hospitalization for PAH, lung transplantation, and death.

The market liked the news. MRK stock climbed 4.70% to $97.22 on Tuesday following the announcement.