Dec 31 (Reuters) - UK's Medicines and Healthcare

products Regulatory Agency said on Tuesday it had approved

Merck's ( MRK ) therapy to treat a rare lung condition, marking

another win for the drugmaker's potential blockbuster.

The therapy, sotatercept, received U.S. approval in March

2024 and is sold under the brand name Winrevair. It is also

approved in European Union and 30 other markets.

The MHRA's approval is based on data from a study of 323

patients with pulmonary arterial hypertension, in which Merck's ( MRK )

therapy was more effective in improving patients' ability to

exercise, compared to placebo.

The U.S. drugmaker acquired sotatercept as part of its $11.5

billion acquisition of Acceleron Pharma in 2021. It has been

expanding its cardiovascular drugs portfolio as it prepares for

a potential hit to sales after key patents for its top-selling

cancer therapy Keytruda expire later this decade.

The regulator said sotatercept can be used with other

medicines in adults with moderate or marked limitations of

physical activity to help improve their exercise capacity.

It said the recommended dosing schedule is one

self-administered injection every three weeks.

As of March 2024, there were 9,263 active PAH patients in

the UK, according to data from National Health Service.

Patients with pulmonary arterial hypertension have high

blood pressure in the vessels that supply blood to the lungs,

which makes the heart work harder to pump blood and can cause

failure of the organ.

Sotatercept works by targeting the activin protein that is

known to play a role in narrowing lung arteries.

Winrevair has garnered sales of $149 million since its

launch in March. Analysts expect its sales to exceed $1 billion

in 2025, according to data compiled by LSEG. The therapy has a

list price of $14,000 per vial in the U.S.

Merck ( MRK ) did not respond to a request for comment on pricing

and availability of the therapy in the UK.

(Reporting by Bhanvi Satija and Sneha S K in Bengaluru; Editing

by Anil D'Silva and Arun Koyyur)