Argenx shares have fallen more than 13% after the surprise futility finding, which overshadowed a mid-stage celiac disease win for a separate asset acquired in the company’s $2.2 billion Forte Biosciences buy.
Argenx is discontinuing a late-stage study of Vyvgart Hytrulo in Sjogren’s disease due to futility, a surprise setback that removes “the next potential blockbuster expansion opportunity” for the drug, William Blair analysts wrote on Thursday.
The biopharma is ending its Phase 3 UNITY trial after an independent data committee determined that the study would not meet its primary endpoint of improving systemic disease activity, according to a Thursday release.
As of market open, argenx’s stock had tumbled nearly 14%, or about $130 per share, resting at around $797 as of 11 a.m. ET.
UNITY had been evaluating argenx’s Vyvgart Hytrulo injection for Sjogren’s, an autoimmune disorder that most often affects moisture glands, with the most common symptoms of dry eyes and dry mouth. Vyvgart Hytrulo is currently approved to treat generalized myasthenia gravis and chronic inflammatory demyelinating polyneuropathy and recently scored a late-stage win in autoimmune myositis, a group of rare diseases that cause the immune system to attack the muscles.
Today’s futility announcement is surprising given that the trial results weren’t expected until the second half of 2027, William Blair wrote in a Thursday note.
Argenx told the firm that the futility analysis included data from more than 500 patients—as compared to the 630 enrolled—indicating that the review may have been conducted earlier than the primary endpoint assessment expected at week 48.
“Sjogren’s disease drug development has been bogged down by high placebo response rates, making it difficult to achieve robust separation versus placebo,” according to William Blair.
In argenx’s Phase 2 RHO study, the asset appeared differentiated in Sjogren’s compared to placebo at week 24. However, the study was underpowered and there was no difference compared to placebo in percentage of patients achieving at least a three-point improvement on an industry scale measuring disease activity, William Blair wrote.
The analysts had previously estimated peak sales of $1.4 billion in Sjogren’s but noted competition in the space, specifically from Novartis’ investigational monoclonal antibody ianalumab and Amgen’s CD40L antagonist fusion protein dazodalibep, both of which have recorded Phase 3 wins.
Meanwhile, argenx announced a mid-stage celiac disease win in a separate release. The Phase 2 trial evaluated the biotech’s investigational CD122 inhibitor FB102, which it picked up from Forte Biosciences in a $2.2 billion acquisition this summer.
Patients receiving FB102 demonstrated a statistically significant change from baseline in a health measure of the small intestine, meeting the study’s primary endpoint. Given the findings, which argenx heralded as the “first Phase 2 evidence that blocking CD122 can prevent gluten-induced intestinal damage in people living with celiac disease,” the biopharma plans to move the asset into late-stage development.
The celiac disease plans expand argenx’s late-stage pipeline ahead of the closely-watched Phase 3 findings expected soon for monoclonal antibody empasiprubart in multifocal motor neuropathy.
