Argenx Halts Phase 3 UplighTED Trials For Thyroid Eye Disease Following Efficacy Concerns

Argenx SE (ARGX) revealed a significant setback on Monday when it terminated its Phase 3 UplighTED clinical trials evaluating Efgartigimod PH20 SC for moderate to severe thyroid eye disease. The decision came after the Independent Data Monitoring Committee (IDMC) determined that the experimental treatment would unlikely meet its primary endpoints, prompting the recommendation to cease further patient enrollment.

Clinical Trial Discontinuation And Market Response

The discontinuation marks a substantial pivot for the Belgian biopharmaceutical company. Based on a futility assessment of unblinded interim data from patients who completed 24 weeks of treatment, the IDMC concluded the trials no longer justified continued execution. Trading floors reacted swiftly to the announcement, with Argenx shares dropping more than 6% in premarket activity.

Understanding Thyroid Eye Disease And The Treatment Rationale

Thyroid eye disease represents a challenging autoimmune disorder frequently accompanying Graves’ disease, affecting approximately 19 individuals per 100,000 in the United States. The condition predominantly impacts women and manifests through ocular symptoms including orbital inflammation, ocular surface dryness, pain, and diplopia. Traditional therapeutic approaches typically rely on corticosteroids or surgical interventions, neither offering comprehensive immune system modulation.

Efgartigimod PH20 SC, formulated under the VYVGART Hytrulo brand, was strategically developed as an alternative mechanism targeting underlying immune dysfunction more precisely than conventional options. The subcutaneous formulation represents an advancement over existing intravenous delivery systems, offering patients greater convenience and flexibility.

Existing Approvals And Commercial Performance

Notably, VYVGART Hytrulo maintains FDA clearance for myasthenia gravis and chronic inflammatory demyelinating polyradiculoneuropathy. The parent molecule, efgartigimod alfa in VYVGART, remains approved for generalized myasthenia gravis in anti-acetylcholine receptor antibody-positive patients. The intravenous formulation demonstrated robust commercial traction, generating $1.13 billion in product net sales during Q3 2025, reflecting substantial growth compared to $0.6 billion in the corresponding prior-year quarter.

Company Response And Future Direction

Dr. Luc Truyen, Chief Medical Officer at Argenx, emphasized that the futility evaluation was strategically planned to provide meaningful interim insights into patient outcomes while enabling responsible assessment of success probability. Following database closure and comprehensive data analysis, the company intends to present detailed findings at upcoming medical conferences, potentially informing subsequent thyroid eye disease research strategies.

Stock Performance Context

Argenx closed previous trading at $877.94, representing a 1.30% decline, establishing the baseline before this latest announcement amplified downward pressure on investor sentiment.