Roche has agreed to buy U.S. biotech firm $89Bio, Inc.(ETNB) for up to $3.5 billion to strengthen its development pipeline of liver and cardiometabolic disease treatments, the Swiss drugmaker said on Thursday.

89Bio shares rose 83% in premarket trading.

The deal would help Roche grow in a field related to the booming weight-loss market, where the company has recently made major inroads.

In a statement, Roche said the deal was worth about $2.4 billion, or up to $3.5 billion when including a non-tradeable contingent value right.

The target company's leading drug pegozafermin, part of a class known as FGF21 analogues, is in the late stages of development to treat metabolic dysfunction-associated steatohepatitis - also known as fatty liver - including advanced stages.

Roche said it would tender to buy all 89bio common stock for $14.50 per share in cash and a contingent value right to receive certain milestone payments of up to $6.00 per share.

It said the acquisition underscores its dedication to advancing therapies in cardiovascular, renal, and metabolic diseases, especially for patients affected by overweight, obesity, and related health challenges such as fatty liver, also known as MASH.

This year, the company acquired rights to an obesity therapy developed by Denmark's Zealand Pharma in a deal worth up to $5.3 billion, and in late 2023, it struck a deal to buy weight-loss drug developer Carmot for $2.7 billion upfront.