Argenx's Vyvgart (efgartigimod alfa-fcab) demonstrates sustained benefit in myositis and Sjögren's syndrome, paving the way for anticipated Phase III clinical trial results.
Data presented at the 2026 European Union of Rheumatology Associations (EULAR) Congress, which will be held in London from June 3 to 6, showed durability of effect for up to a year in myositis and up to 72 weeks in Sjögren's syndrome.
One-year data show maintenance of the positive effect of myositis treatment.
The ALKIVIA+ study (NCT05979441) is an ongoing, open-label extension study that enrolled patients with myositis who completed the 24-week, double-blind, placebo-controlled Phase II ALKIVIA study (NCT05523167).
After 52 weeks, 37.5% of patients receiving continuous Vivgart maintained the significant improvement in the global improvement scale (TIS) noted at week 24. Among patients who switched from placebo to Vivgart after 24 weeks, a similar significant improvement in the TIS was achieved in 33.3%. Moderate improvement rates on the TIS were also similar in both groups, at 75.0% and 66.7%, respectively.
In patients receiving Vivgart continuously, the mean TIS was 52.19, while in patients switching from placebo to Vivgart, the mean TIS was 49.62, both achieved by week 52.
The TIS is a composite index based on six core indicators, including muscle strength, physician and patient global assessment of disease activity, physical function, enzyme levels, and extramuscular activity. Higher TIS values reflect greater overall clinical improvement. Moderate and significant improvement are defined as TIS ≥40 and ≥60, respectively.
The safety profile remained stable throughout the study, with no increase in adverse events observed with longer exposure.
Myositis can cause severe and irreversible damage to muscles and organs, leading to loss of independence and significant burden for patients. Sjögren's disease can cause dry eyes and mouth, chronic fatigue, and joint pain. It can also affect multiple organ systems and lead to complications involving the nervous system.
Dr Hector Chinoy, study author and professor of rheumatology and neuromuscular diseases at the University of Manchester, said: «Patients with autoimmune myositis face a significant challenge: their immune system attacks its own body, causing irreversible muscle loss, weakness, pain and reduced quality of life, while the limited number of treatments available can have significant side effects and be difficult to tolerate in the long term.».
Phase III clinical trials of Vyvgart for myositis are currently underway, with preliminary results expected in the third quarter of 2026.
Resistance to Sjogren's disease according to the Vivgart classification
The RHO+ study (NCT06203457) is a 48-week, open-label extension study evaluating patients with Sjögren's syndrome who continued to receive Vivgart and those who crossed over from placebo to Vivgart after completing the 24-week double-blind treatment period in the Phase II RHO study (NCT05817669).
At week 72, median ClinESSDAI values were low in both groups: 2.5 in the efargatimod group and 2.0 in patients switching from placebo to efargatimod. Low disease activity is defined by the ClinESSDAI value.
Vivgart was well tolerated, and no new signals indicating potential safety concerns were identified during long-term use in participants with Sjögren's syndrome.
Sjögren's syndrome is a chronic autoimmune disorder. The immune system mistakenly attacks healthy cells in the glands that produce moisture, primarily the tear and salivary glands.
A Phase III UNITY clinical trial is currently underway to evaluate the efficacy and safety of efargatimod in patients with moderate to severe Sjögren's syndrome. Preliminary results are expected in the second half of 2027.
Vyvgart was first approved by the US Food and Drug Administration (FDA) for the treatment of generalized myasthenia gravis (gMG) in 2021. Since then, Argenx has developed a subcutaneous version of the drug, Vyvgart Hytrulo (efargitimod alfa and hyaluronidase-qvfc). This first-in-class antibody fragment blocks the neonatal Fc receptor (FcRn) to reduce levels of circulating IgG autoantibodies.
The article "Argenx's Vyvgart Shows High Efficacy in Myositis and Sjogren's Syndrome" was originally created and published by Clinical Trials Arena, a brand of GlobalData.
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