Merck’s phase 3 HYPERION study of Winrevair meets primary endpoint for PAH

Merck’s phase 3 HYPERION study of Winrevair meets primary endpoint for PAH

By, Admin 25 June 2025

Overview

Merck, known as MSD outside of the United States and Canada, today announced positive topline results from the phase 3 HYPERION study evaluating Winrevair (sotatercept-csrk) versus placebo (both in combination with background therapy) in recently diagnosed adults with pulmonary arterial hypertension (PAH, WHO Group 1) functional class (FC) II or III at intermediate or high risk of disease progression. HYPERION met its primary endpoint of time to clinical worsening (TTCW) as measured by a composite endpoint of all-cause death, the need for non-planned PAH-related hospitalization > 24 hours, atrial septostomy, lung transplantation, or PAH deterioration.

HYPERION Confirms Winrevair’s Efficacy in PAH on Background Double Therapy

  • In the HYPERION Phase 3 study, Winrevair was added to background therapy in patients with PAH (pulmonary arterial hypertension), with 72.2% on double therapy within 12 months of initial diagnosis.
  • Winrevair demonstrated a statistically significant and clinically meaningful reduction in the risk of clinical worsening events compared to placebo.
  • HYPERION is the third Phase 3 trial confirming the efficacy of Winrevair in adults with PAH.
  • The previous two Phase 3 studies were:
  • STELLAR, presented at ACC.23
  • ZENITH, presented at ACC.25
  • Unlike HYPERION, STELLAR and ZENITH enrolled patients primarily on triple therapy, indicating Winrevair's benefit even in earlier-stage or less-intensive treatment settings.
  • The safety profile of Winrevair in HYPERION was generally consistent with findings from earlier studies.

HYPERION Trial Concludes Early Following Positive Interim Results

  • In January, it was announced that the HYPERION Phase 3 trial was stopped early and advanced to final analysis.
  • This decision was based on:
  • Positive interim results from the ZENITH Phase 3 trial, and
  • A comprehensive review of data from the entire Winrevair clinical program.
  • Following early termination, all HYPERION participants were offered continued access to Winrevair via the SOTERIA open-label extension study.

Expert comment from Dr. Vallerie McLaughlin

  • PAH is a progressive and debilitating disease with a poor prognosis that can be difficult to diagnose and treat. Patients often struggle for years to find a treatment plan that helps manage the disease, so it’s critical to provide new options earlier in the treatment journey,” said Dr. Vallerie McLaughlin, Kim A Eagle MD Endowed Professor of Cardiovascular Medicine and Director, Pulmonary Hypertension Program, University of Michigan in Ann Arbor. 
  • The HYPERION study demonstrated that Winrevair on top of background therapy met its primary outcome measure of reduction in the time to clinical worsening events in adults who have been recently diagnosed with PAH. Winrevair has brought significant optimism to patients, their families and investigators and we thank all study participants for being part of this important study.”

Expert comment from Dr. Joerg Koglin: SVP, Merck Research Laboratories

  • To date, the strong clinical profile of Winrevair, a first-in-class activin signalling inhibitor, had been primarily established through previous studies in a prevalent patient population comprised of patients that were several years into their treatment journey. These positive results from HYPERION expand on the body of clinical evidence now including recently diagnosed adults, supporting the practice-changing potential of Winrevair in a broad spectrum of PAH patients, including those earlier in their treatment journey,"" said Dr. Joerg Koglin, senior vice president, head of general and specialty medicine, global clinical development, Merck Research Laboratories. 
  • We look forward to presenting these data to the scientific community at a future medical meeting.”

Results from HYPERION will be presented at an upcoming medical meeting later this year and will be submitted to regulatory authorities. Winrevair is currently approved in more than 45 countries based on the results from the STELLAR study.

The HYPERION trial

  • The HYPERION study (NCT04811092) is a global, double-blind, placebo-controlled clinical trial to evaluate Winrevair when added to background PAH therapy in newly diagnosed intermediate or high-risk PAH patients. 
  • Participants who enrolled in the study had a diagnosis of symptomatic PAH (WHO Group 1, classified as FC II [21.3%; 68/320 participants] or III [78.8%; 252/320 participants] within 12 months of study screening. 
  • Eligible participants had a confirmed diagnosis of PAH in any of the following subtypes: idiopathic PAH (59.4%; 190/320), heritable PAH (5.9%; 19/320), PAH associated with connective tissue diseases (CTD) (30.3%; 97/320), drug- or toxin-induced PAH (2.5%; 8/320), or PAH associated with simple, congenital systemic-to-pulmonary shunts at least 1 year following repair (1.9%; 6/320). 
  • The study excluded patients with PAH Group 1 subtypes: human immunodeficiency virus (HIV)-associated PAH and PAH associated with portal hypertension, schistosomiasis-associated PAH, pulmonary veno occlusive disease, and pulmonary capillary hemangiomatosis.

Trial process

  • The study enrolled 320 study participants over the age of 18, who were randomized in a 1:1 ratio to receive either Winrevair or placebo both on top of background therapy. 
  • Participants were at an intermediate to high risk of disease progression and on stable doses of double (72.2%; 231/320 participants) or triple (27.8%; 89/320 participants) background PAH therapies for at least 90 days prior to screening. 
  • A majority (83.4%; 267/320 participants) were not on prostacyclin-infusion therapy.

Primary outcome

  • The primary composite outcome measure is TTCW as measured by first confirmed morbidity or mortality event. 
  • Clinical worsening events are defined as all-cause death, non-planned PAH worsening-related hospitalization of = 24 hours, atrial septostomy, lung transplantation, and deterioration in six-minute walk test from baseline combined with at least one of the following changes including worsening of WHO FC from baseline, signs/symptoms of increased right heart failure, addition of a background PAH therapy or change in the background PAH therapy delivery route to parenteral.

Secondary outcome

  • Secondary outcome measures were assessed relative to baseline at Week 24: proportion of participants achieving multicomponent improvement (consisting of improvement in 6MWD, improvement in N-terminal pro-B-type natriuretic peptide (NT-proBNP) level and improvement in WHO FC or maintenance of WHO FC II) as well as additional measures.

FDA approved Winrevair

  • Winrevair is FDA-approved for the treatment of adults with pulmonary arterial hypertension (PAH, WHO Group 1) to increase exercise capacity, improve WHO functional class (FC) and reduce the risk of clinical worsening events. 
  • Winrevair is the first activin signaling inhibitor therapy approved to treat PAH. 
  • Winrevair improves the balance between pro-proliferative and anti-proliferative signaling to modulate vascular proliferation. 
  • In preclinical models, Winrevair induced cellular changes that were associated with thinner vessel walls, partial reversal of right ventricular remodelling, and improved hemodynamics.

Winrevair is the subject of a licensing agreement with Bristol Myers Squibb.

About the condition: Pulmonary arterial hypertension

  • Pulmonary arterial hypertension (PAH) is a rare, progressive and life-threatening blood vessel disorder characterized by the constriction of small pulmonary arteries and elevated blood pressure in the pulmonary circulation. 
  • Approximately 40,000 people in the US are living with PAH. 
  • The disease progresses rapidly for many patients. 
  • PAH results in significant strain on the heart, leading to limited physical activity, heart failure and reduced life expectancy. 
  • The five-year mortality rate for patients with PAH is approximately 43%.

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