A hoped-for new use of one of Europe's best-selling biotech drugs has failed.

Argenx said Thursday it is ending its Phase 3 UNITY trial, which tested an injectable form of Vyvgart in adults with moderate to severe Sjögren's disease. An independent data committee looked at early results and found the study would not meet its main goal: lowering overall disease activity compared with a placebo at 48 weeks.

Sjögren's is an autoimmune disease that damages the glands that make tears and saliva. Its most common symptoms are dry eyes and dry mouth. There is no approved treatment, Reuters reported, which is why analysts saw the trial as a big chance for Vyvgart.

"We are disappointed by this result, first and foremost for people with Sjögren's disease," said Luc Truyen, the company's medical director. He called it one of the most complex diseases in immunology. No new safety concerns turned up, the company said.

Investors reacted fast. Analysts at William Blair had estimated peak Sjögren's sales of $1.4 billion and called it "the next potential blockbuster expansion opportunity" for the drug, BioSpace reported. The analysts were surprised, since results had not been expected until the second half of 2027. The review used data from more than 500 of the 630 patients enrolled.

It is a hard disease to study. William Blair noted that patients on placebo often improve a lot, which makes it tough for a drug to stand out. Rival drugs from Novartis and Amgen have posted Phase 3 wins in the disease.

Vyvgart is already approved for two other autoimmune conditions, generalized myasthenia gravis and chronic inflammatory demyelinating polyneuropathy. Argenx had more upbeat news the same day. A separate drug it bought this summer met its main goal in a mid-stage celiac disease trial.

The company says it will study the full trial data once the database is locked.

What we know: The UNITY trial is over, and no new safety issues were found.
What we don't: Why the drug failed and whether argenx will try Sjögren's again.