argenx announced positive Phase 2 results for FB102 in celiac disease, meeting its primary endpoint (p=0.0176) and prompting plans for a Phase 3 trial. However, this success was overshadowed by a major setback as an independent board recommended halting the Phase 3 trial of argenx's blockbuster drug Vyvgart in Sjögren's disease for futility. The unexpected clinical failure sent argenx shares tumbling 15% on October 8, 2026, wiping out a key expansion opportunity for its core franchise.
FB102 Phase 2 trial results
- ▪The Phase 2 study of FB102 met its primary endpoint of change from baseline in the ratio of villus height-to-crypt depth (Vh:Cd) at day 78 versus placebo in adults with celiac disease undergoing a gluten challenge (p=0.0176).
- ▪The Phase 2 study of FB102 enrolled 126 patients with confirmed celiac disease who were symptom-free on a strict gluten-free diet for at least 12 months.
- ▪argenx plans to advance FB102 into Phase 3 development for celiac disease based on the positive Phase 2 clinical evidence.
Mechanism and indications of FB102
- ▪FB102 is designed to block CD122 to selectively modulate IL-2 and IL-15 pathways that cause inflammation while preserving regulatory T-cell function and immune balance.
- ▪The U.S. Food and Drug Administration has granted FB102 Fast Track Designation for celiac disease.
- ▪argenx is evaluating FB102 as a potential treatment in other autoimmune diseases, including vitiligo and alopecia areata.
Termination of Sjögren's disease study
- ▪The timing of the Sjögren's study termination surprised Wall Street analysts, who were not expecting results from the Phase 3 trial until the second half of 2027.
- ▪An independent monitoring board recommended ending the Phase 3 Unity study of efgartigimod SC (Vyvgart) in Sjögren's disease for futility following an interim analysis.
Impact on argenx share price
- ▪argenx shares fell 15% on October 8, 2026, following the announcement of the Phase 3 Sjögren's disease study failure.
- ▪Despite the share price decline on October 8, 2026, argenx maintained a market capitalization of approximately $50 billion.
Vyvgart sales performance and estimates
- ▪Analyst estimates for the overall annual peak sales of Vyvgart, excluding Sjögren's disease, range from $11 billion to $17 billion.
- ▪Sales of Vyvgart and its subcutaneous version, Vyvgart Hytrulo, generated $1.5 billion for argenx in the second quarter of 2026.
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