Swiss pharmaceutical giant Roche said Wednesday that it had struck a deal worth up to $5.3 billion to develop Danish biotech Zealand Pharma’s obesity drug candidate, as the two firms seek to compete in the burgeoning weight loss drug market.

The deal will see the two companies co-develop and co-commercialize petrelintide, Zealand Pharma’s amylin analog as a standalone therapy, as well as a fixed-dose combination with Roche’s lead incretin asset CT-388. 

Under the agreement, Zealand Pharma will receive upfront cash payments of $1.65 billion, with the potential of milestone payments taking the total to up to $5.3 billion, depending on phase-3 trials and sales development, Roche said in a statement.

Shares of Zealand Pharma jumped 29% shortly after the announcement, and were trading up 23% by 10:5- a.m. London time, while Roche added 4.6%.

Shares of obesity drug giant Novo Nordisk, meanwhile, slipped 3.9% during Wednesday’s session as Eli Lilly dipped 1.5% in pre-market trade.

Zealand Pharma CEO and President Adam Steensberg told CNBC that the deal showed the two companies’ “strong commitment to lead in the obesity space in the future.”

“Roche has convinced us that they have ambition to take leadership in this therapeutic space,” he told CNBC via video call Wednesday.

The Danish biotech has long pointed to amylin analogs as the “next generation” of weight loss treatment. They work by mimicking a hormone that is co-secreted with insulin in the pancreas to increase satiety. This differs from GLP-1 agonists, which mimic incretin hormones produced in the gut to suppress appetite and regulate blood sugar.

“In contrast to GLP-1s that make make people lose appetite, petrelintide can help people feel fuller faster,” Steensberg said.