Merck Receives European Commission Approval for WINREVAIR™ (sotatercept) in Combination With Other Pulmonary Arterial Hypertension (PAH) Therapies, for the Treatment of PAH in Adult Patients With Functional Class II-III

WINREVAIR is the first activin signaling inhibitor therapy for PAH approved in Europe

Merck (NYSE: MRK), known as MSD outside of the United States and Canada, announced today that the European Commission (EC) has approved WINREVAIR™ (sotatercept), in combination with other pulmonary arterial hypertension (PAH) therapies, for the treatment of PAH in adult patients with World Health Organization (WHO) Functional Class (FC) II to III, to improve exercise capacity. WINREVAIR is the first and only activin signaling inhibitor therapy for PAH approved in all 27 member states of the EU, as well as Iceland, Liechtenstein and Norway. WINREVAIR works by improving the balance between pro- and anti-proliferative signaling to regulate vascular cell proliferation underlying PAH. The EC approval of WINREVAIR is based on safety and efficacy results from the Phase 3 STELLAR trial.

“The European Commission’s approval of WINREVAIR is an important step for patients,” said Dr. Joerg Koglin, senior vice president and head of general medicine, global clinical development, Merck Research Laboratories. “WINREVAIR is the first therapy targeting the activin signaling pathway. We are proud to bring this innovative treatment to more patients and remain committed to further investigating the potential of WINREVAIR in areas where there are unmet needs in the management of PAH.”

“Pulmonary arterial hypertension is a devastating disease for patients, who suffer from debilitating symptoms that can severely limit their daily activities,” said Dr. Marc Humbert, Professor of Medicine and Director of the Pulmonary Hypertension Reference Center at Université Paris-Saclay. “New treatment opinions continue to be needed for patients. Based on the Phase 3 STELLAR study, adding WINREVAIR to background PAH therapy improved exercise capacity, reduced the risk of death or clinical worsening events and improved functional class compared to background PAH therapy alone. These findings are significant and reinforce that WINREVAIR, in combination with other PAH therapies, should be considered as a new standard of care for the treatment of functional class II and III adult patients.”

The EC approval is based on the Phase 3 STELLAR trial, which compared WINREVAIR (n=163) to placebo (n=160), both in combination with background standard of care therapies in adult patients with PAH (WHO Group 1, FC II or III). The primary efficacy endpoint was change from baseline at Week 24 in six-minute walk distance. Treatment with WINREVAIR resulted in a statistically significant and clinically meaningful improvement in six-minute walk distance of 40.8 meters over placebo (95% CI: 27.5, 54.1; p<0.001). WINREVAIR also significantly improved multiple important secondary outcome measures, including reducing the risk of death or clinical worsening. In a post hoc analysis provided to EMA, time to death or clinical worsening was defined as the time from randomization to the first occurrence of deterioration of PAH, PAH-specific hospitalization, worsening-related listing for lung and/or heart transplant, need for atrial septostomy, or death from any cause. There was an 82% reduction in the risk of death or clinical worsening with WINREVAIR on top of background therapy versus background therapy alone (number of events: 7 vs 29, HR=0.182; 95% CI: 0.075, 0.441; p<0.001).

WINREVAIR is administered once every 3 weeks as a single injection under the skin and may be administered by patients or caregivers with guidance, training and follow-up from a healthcare provider. Healthcare providers and patients/caregivers should refer to the Instructions for Use for information on the proper preparation and administration of WINREVAIR.

This approval by the EC for WINREVAIR is valid in all 27 member states of the EU, as well as Iceland, Liechtenstein and Norway. WINREVAIR was previously granted Priority Medicines (PRIME) and orphan designation by the EMA for the treatment of PAH.

On March 26, 2024, the FDA approved WINREVAIR in the U.S. 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.

About STELLAR

The STELLAR study (NCT04576988) was a global, double-blind, placebo-controlled, multicenter, parallel-group clinical trial in which 323 patients with PAH (WHO Group 1 FC II or III) were randomized 1:1 to WINREVAIR (target dose 0.7 mg/kg) (n=163) or placebo (n=160) plus stable background therapy administered subcutaneously once every 3 weeks.

The most common PAH etiologies were idiopathic PAH (59%), heritable PAH (18%), and PAH associated with connective tissue diseases (CTD) (15%). Most participants were receiving either three (61%) or two (35%) background drugs for PAH, and 40% were receiving prostacyclin infusions. The mean time from PAH diagnosis was 8.8 years. Patients had a WHO FC II (49%) or III (51%) at baseline.

About WINREVAIR™ (sotatercept-csrk) for injection, for subcutaneous use, 45 mg, 60 mg

WINREVAIR, the first activin signaling inhibitor therapy approved to treat PAH, 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 remodeling, and improved hemodynamics.

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

Selected Safety Information for WINREVAIR in the U.S.

WINREVAIR may increase hemoglobin and lead to erythrocytosis. Severe erythrocytosis may increase the risk of thromboembolic events or hyperviscosity syndrome. Monitor Hgb before each dose for the first 5 doses, or longer if values are unstable, and periodically thereafter, to determine if dose adjustments are required.

WINREVAIR may decrease platelet count and lead to severe thrombocytopenia, which may increase the risk of bleeding; thrombocytopenia occurred more frequently in patients also receiving prostacyclin infusion. Do not initiate treatment if platelet count is <50,000/mm³. Monitor platelets before each dose for the first 5 doses, or longer if values are unstable, and periodically thereafter to determine if dose adjustments are required.

In clinical studies, serious bleeding (e.g., gastrointestinal, intracranial hemorrhage) was reported in 4% of patients taking WINREVAIR and 1% of patients taking placebo. Serious bleeding was more likely in patients on prostacyclin background therapy and/or antithrombotic agents, or with low platelet counts. Advise patients about signs and symptoms of blood loss. Do not administer WINREVAIR if the patient is experiencing serious bleeding.

WINREVAIR may cause fetal harm when administered to a pregnant woman. Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential to use an effective method of contraception during treatment with WINREVAIR and for at least 4 months after the final dose. Pregnancy testing is recommended for females of reproductive potential before starting WINREVAIR treatment.

Based on findings in animals, WINREVAIR may impair female and male fertility. Advise patients on the potential effects on fertility.

The most common adverse reactions occurring in the Phase 3 clinical trial (≥10% for WINREVAIR and at least 5% more than placebo) were headache (24.5% vs 17.5%), epistaxis (22.1% vs 1.9%), rash (20.2% vs 8.1%), telangiectasia (16.6% vs 4.4%), diarrhea (15.3% vs 10.0%), dizziness (14.7% vs 6.2%), and erythema (13.5% vs 3.1%).

Because of the potential for serious adverse reactions in the breastfed child, advise patients that breastfeeding is not recommended during treatment with WINREVAIR, and for 4 months after the final dose.

About pulmonary arterial hypertension (PAH)

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 U.S. and 30,000 people in the EU 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%, based on data from the REVEAL registry (patients enrolled between March 2006 and December 2009).

About Merck

At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.merck.com and connect with us on X (formerly Twitter), Facebook, Instagram, YouTube and LinkedIn.

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Please see Prescribing Information for WINREVAIR (sotatercept-csrk) at http://www.merck.com/product/usa/pi_circulars/w/winrevair/winrevair_pi.pdf, Patient Information for WINREVAIR at http://www.merck.com/product/usa/pi_circulars/w/winrevair/winrevair_ppi.pdf, and Instructions for Use for WINREVAIR (1-vial kit, 2-vial kit) at https://www.merck.com/product/usa/pi_circulars/w/winrevair/winrevair_ifu_1-vial_2-vial_kits.pdf.

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