On Tuesday, the U.S. Food and Drug Administration granted approval to Merck's (MRK.N) latest treatment for adults grappling with high blood pressure due to the constriction of lung arteries, marking another potential blockbuster addition to the pharmaceutical giant's repertoire. Merck's shares soared over 4% in extended trading following the announcement.

The newly approved therapy, branded Winrevair, targets the treatment of pulmonary arterial hypertension (PAH), a condition affecting approximately 40,000 individuals in the United States alone. "We look forward to making a significant difference for these patients who are grappling with a disease where the five-year mortality rate stands at 43%," remarked Jannie Oosthuizen, president of Merck's U.S. Human Health business, in a statement to Reuters.

According to Oosthuizen, Winrevair will be priced at $14,000 per vial. Based on trial data, most patients are expected to use a single vial every three weeks, translating to an annual cost of $238,000 per patient.

Merck anticipates launching the drug by the end of April, having acquired the rights to Winrevair through its $11.5 billion acquisition of Acceleron Pharma in 2021. The company has been strategically bolstering its portfolio of cardiovascular drugs as a proactive measure against potential revenue impacts to its cancer treatment Keytruda, the world's leading medicine, from biosimilars expected in the coming years.

Sotatercept, known chemically as Winrevair, is the first of its class of drugs to secure FDA approval. This class targets a specific protein known as activin. PAH results from the narrowing of arteries in the lungs, leading to heightened blood pressure and accompanying symptoms such as breathlessness, chest pain, and dizziness. The increased pressure on the heart can eventually lead to heart failure.

"We anticipate sotatercept experiencing a robust initial launch and swiftly becoming a cornerstone of care for eligible PAH patients," stated J.P. Morgan analyst Chris Schott in an analytical note. Schott predicts the therapy to achieve peak sales of approximately $5 billion by 2030.

Merck's drug approval was based on a 24-week-long late-stage trial involving 323 PAH patients. The results demonstrated significant improvement in exercise capacity among patients treated with the drug, with a notable increase of 40.8 meters in their 6-minute walking distance compared to those on the placebo.