KENILWORTH, N.J. — Merck will spend about $11.5 billion to buy Acceleron Pharma and its potential treatment for high blood pressure in vessels that connect the lungs heart.

Merck will pay $180 per share in cash for Acceleron, the company said today.

Acceleron is running late-stage studies of a potential treatment for patients with pulmonary arterial hypertension, a potentially life-threatening blood vessel disorder.

The drug represents a “potential blockbuster” and a way for for Merck to add a new source of revenue, Mizuho Securities USA analyst Mara Goldstein wrote.

Merck has long faced investor criticism that it’s far too dependent for revenue from its drug Keytruda, which is now approved for treating a dozen types of cancer.

Keytruda brought in $4.2 billion for Merck in the second quarter, more than one-third of the company’s total revenue.

Merck also is developing a potential COVID-19 treatment, and the company expects to have results from late-stage research into that drug by later this year.

Acceleron also makes Reblozyl, a treatment for anemia in some rare blood disorders. The company developed and sells that drug through a collaboration with another drugmaker, Bristol Myers Squibb Co., which also is the largest institutional shareholder in the Cambridge, Massachusetts, company, with more than an 11% stake.

Reblozyl has received approval from regulators in the United States, Europe, Canada and Australia.

The acquisition is expected to close in the fourth quarter.

Shares of Merck & Co. Inc. climbed 71 cents to $75.80 before markets opened today, while Acceleron Pharma Inc. climbed about $1 to $176.35.