Merck to buy Prometheus Biosciences in $11 billion deal

The deal will allow the pharmaceutical company to move into immunology after promising experimental treatment for Crohn's disease and ulcerative colitis

Merck's headquarters in New Jersey. The company will pay $200 per share for Prometheus Biosciences. Reuters

US pharmaceutical company Merck & Co will buy Prometheus Biosciences for about $10.8 billion, picking up a promising experimental treatment for ulcerative colitis and Crohn's disease and building up its presence in immunology.

Merck will pay $200 per share for the California-based biotechnology company that specialises in treatments for autoimmune diseases, the drug maker said on Sunday.

The deal represents a 75 per cent premium to the $114.01 closing price for Prometheus shares on Friday.

“This is allowing us to move into immunology in a strong way and will allow us sustainable growth, we think, well into the 2030s given the long patent life,” Merck chief executive Robert Davis said.

The Prometheus drug, PRA023, being developed to treat ulcerative colitis, Crohn’s disease and other autoimmune conditions, could be a multibillion-dollar seller for Merck, Mr Davis said.

The recent release of encouraging Phase II clinical trial results drove Merck to pounce.

“We've been watching their clinical development programme for a while,” Mr Davis said.

If the deal closes in the third quarter of this year as hoped, Merck could launch a late-stage ulcerative colitis study of the drug in the fourth quarter or first quarter of 2024, he added.

Merck has been looking for deals to protect itself from eventual revenue loss as patents on its blockbuster cancer immunotherapy Keytruda begin to expire towards the end of the decade. The company reported nearly $21 billion in Keytruda sales last year.

Revenue from the Prometheus acquisition could start to roll in around the time Keytruda patents could potentially expire, Mr Davis said.

Watch: US FDA approves second anti-Covid pill

He compared the deal to one he struck in 2021 for Acceleron, which allowed Merck to quickly build out its pipeline of cardiovascular drugs.

“I believe now we have a very strong portfolio in the cardiometabolic space. We see this acquisition of Prometheus building out a similar portfolio in the immunology space,” Mr Davis said, adding that Merck brings scale, global reach and significant capital to deploy.

Last summer, Merck was reportedly in talks to buy cancer focused biotech Seagen, but rival Pfizer ended up striking a $43 billion deal for Seagen last month.

Mr Davis said Merck would continue to be opportunistic on acquisitions, but is agnostic about size.

“We look where we see the most compelling science, and where that science aligns with value we move,” Mr Davis said, noting that the company is not interested in large transformative or cost-synergy driven deals.

Merck's talks with Prometheus were first reported by The Wall Street Journal.

In February, the company forecast 2023 earnings below Wall Street estimates and a steep decline in sales of its Covid-19 antiviral treatment.