argenx halts Phase 3 UNITY trial of efgartigimod in Sjögren's disease
argenx has discontinued its Phase 3 UNITY study of efgartigimod subcutaneous (SC) in adults with moderate-to-severe Sjögren's disease after an Independent Data Monitoring Committee (IDMC) recommended halting the trial for futility. An interim analysis led the IDMC to conclude the study could not meet its primary endpoint, the change from baseline in systemic disease activity as measured by the clinESSDAI score at Week 48. The company reported that no new safety signals were identified and that the drug's safety profile remained consistent with prior experience.
The setback is a notable one for argenx, whose FcRn-blocking franchise has otherwise had a strong commercial trajectory. Efgartigimod's mechanism, reducing circulating IgG autoantibodies by targeting the neonatal Fc receptor, was considered a biologically plausible route into Sjögren's disease, given the prominent role of anti-Ro/SSA and other IgG autoantibodies in the condition. The UNITY readout suggests that IgG reduction alone may be insufficient to suppress the multifactorial inflammatory cascade driving systemic disease activity in this indication.
A difficult disease to crack
Chief Medical Officer Luc Truyen acknowledged the disappointing outcome, noting that "Sjögren's disease is one of the most heterogeneous and complicated diseases in immunology." The company said it will conduct a full analysis of the trial data following database lock and intends to share findings with the Sjögren's research community. That data package could still yield mechanistic insights into why IgG depletion did not translate into clinical benefit at Week 48.
Sjögren's disease affects an estimated millions of people globally, predominantly women at a 9:1 female-to-male ratio, and remains without a disease-modifying approved therapy targeted at systemic manifestations. Patients enrolled in UNITY were required to test positive for anti-Ro/SSA autoantibodies and have a clinESSDAI score of six or above, representing a moderate-to-severe systemic phenotype. The study was randomised, double-blind and placebo-controlled, with key secondary endpoints including low disease activity response rates, the STAR responder tool, and patient-reported symptom burden via the DiSSA diary.
Market context and competitive landscape
The Sjögren's space has long been viewed as a graveyard for late-stage trials, with multiple prior failures across different mechanisms. The absence of an approved systemic therapy has nonetheless kept the indication attractive to developers, including those investigating B-cell-depleting biologics, type I interferon pathway inhibitors, and co-stimulation blockers. Several programmes remain in mid-to-late stage development, meaning competitive pressure on any eventual entrant is likely to be significant when approvals do materialise.
For argenx, the UNITY failure does not fundamentally alter its commercial position. Efgartigimod is already approved and generating revenue in generalised myasthenia gravis and chronic inflammatory demyelinating polyneuropathy, with further indications under evaluation. The company's FcRn platform retains a broad pipeline, and the Sjögren's data, once fully analysed, may help the field better stratify patients or identify biomarkers that future trial designs can target. Investors will be looking to argenx's next portfolio update for clarity on how the company intends to reallocate the development resources previously assigned to UNITY.