argenx shares fall sharply after futility stop ends Phase 3 Sjögren's study of efgartigimod

ARGX shares fell sharply on October 8 after argenx said it will discontinue the Phase 3 UNITY study of efgartigimod subcutaneous (SC) in moderate-to-severe Sjögren's disease. Market posts put the drop at 15.7% and 11.7% around 10:00 ET, and Investing.com reported declines of 15.86% and 11.04% across argenx's Euronext and Nasdaq listings.

The decision followed a recommendation from an Independent Data Monitoring Committee to stop the study for futility after an interim analysis. The committee concluded UNITY was unable to meet its primary endpoint, the change from baseline in systemic disease activity at Week 48, according to argenx. Patients had been randomized to weekly efgartigimod SC or placebo over 48 weeks. The company said safety was consistent with the drug's established profile, with no new safety signals, and it disclosed no efficacy data. "We are disappointed by this outcome, most of all for people living with Sjögren's disease," chief medical officer Luc Truyen said.

The stop removes one branch of the indication expansion that investors had been pricing into efgartigimod. The drug's approved uses are unaffected: VYVGART is approved for generalized myasthenia gravis and, in Japan only, immune thrombocytopenia, while VYVGART Hytrulo is approved for generalized myasthenia gravis and chronic inflammatory demyelinating polyneuropathy (CIDP).

What to watch: full UNITY data have not been released, and investors will look for whether the futility finding is specific to Sjögren's disease or carries read-through to other autoimmune indications argenx is pursuing. Sales in the approved indications remain the main driver of near-term results.