American pharmaceutical giant Merck announced Sunday that it has acquired Prometheus Biosciences for $10.8 billion to boost its production of immunosuppressive drugs .

Merck said in a statement that the two companies "concluded a definitive transaction under which Merck agreed, through its subsidiary, to acquire Prometheus for $200 cash per share, for a total value of $10.8 billion."

California-based Prometheus closed at $114.01 a share on the New York Stock Exchange on Friday.

The company is developing therapies for immune diseases, including ulcerative colitis and Crohn's disease, or inflammatory bowel disease.

"The agreement with Prometheus will accelerate our growing presence in the field of immunology, where there are still significant unmet needs for patients," said Robert Davis, Chairman and CEO of Merck, according to the statement.

He added that the deal diversifies Merck's portfolio and helps propel its "growth well into the next decade."

Merck's financial results were better-than-expected in the fourth quarter of 2022, thanks in part to strong cancer drug sales, and despite lower demand for the anti-COVID treatment molnopiravir.

From September to December, the company, known as MSD, had sales outside the United States and Canada of $13.8 billion, up 2 percent year-on-year.