• If approved by the European Commission, WINREVAIR will be the first activin signaling inhibitor therapy for PAH in Europe, offering a new treatment option for certain adults with this rare, progressive disease
• Milestone highlights Merck’s focus on global filings to expand access to WINREVAIR and commitment to patients living with PAH

RAHWAY, N.J. / Jun 28, 2024 / Business Wire / Merck (NYSE: MRK), known as MSD outside of the United States and Canada, announced today that the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) recommended the approval of 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 was previously granted Priority Medicines (PRIME) and orphan designation by the EMA for the treatment of PAH. The European Commission (EC) will now review the CHMP recommendation, and the EC’s decision on the marketing authorization application of WINREVAIR in the EU, Iceland, Liechtenstein and Norway is expected in the third quarter of 2024.

“PAH is a progressive and debilitating rare disease,” said Dr. Joerg Koglin, senior vice president and head of general medicine, global clinical development, Merck Research Laboratories. “There is still a significant need for new therapies for patients. This positive opinion marks the first step toward expanding access to our first-in-class activin signaling inhibitor therapy, WINREVAIR, for eligible adults with PAH in Europe. We are pleased with the CHMP recommendation and look forward to the European Commission’s decision.”

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.

The CHMP recommendation is based on data from the Phase 3 STELLAR trial of WINREVAIR on top of background PAH therapy compared to background therapy alone. WINREVAIR demonstrated a statistically significant and clinically meaningful improvement in 6-minute walk distance, the study’s primary endpoint, and on multiple important secondary outcome measures, including reducing the risk of death from any cause or PAH clinical worsening events. These results were published in The New England Journal of Medicine.

“WINREVAIR is the first activin signaling inhibitor therapy and is proposed to modulate the vascular proliferation underlying PAH,” said Dr. Marius Hoeper, Hannover Medical School, Germany. “Based on the clinical benefits demonstrated in primary and secondary outcome measures in the Phase 3 STELLAR study, WINREVAIR has the potential to play a critical role in the treatment of appropriate adults with PAH. It is very encouraging that physicians in Europe may soon have a novel treatment option available that targets a new PAH treatment pathway.”

Through the CHMP recommendation, the EMA is the second regulatory body to recognize the potential of WINREVAIR in the treatment of PAH based on a review of pivotal efficacy and safety data. In March 2024, WINREVAIR (sotatercept-csrk) was approved by the U.S. Food and Drug Administration (FDA).

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

In the U.S., 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, 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.