Amsterdam, Netherlands, August 17, 2026
argenx SE announced positive topline results from the Phase 3 ALKIVIA study evaluating VYVGART Hytrulo® (efgartigimod alfa and hyaluronidase-qvfc) in adults with autoimmune myositis, a group of autoimmune diseases characterized by inflammation and progressive muscle weakness. The study met its primary endpoint, with patients receiving efgartigimod demonstrating a statistically significant and clinically meaningful improvement in Total Improvement Score (TIS) at Week 52 compared with placebo. In the combined population of immune-mediated necrotizing myopathy (IMNM) and dermatomyositis (DM), the mean TIS was 47.95 with efgartigimod versus 32.56 with placebo, representing a 15.4-point treatment difference (p=0.0011). The result marks an important clinical development milestone for argenx as it evaluates the potential of targeted FcRn inhibition in autoimmune myositis, particularly IMNM, where there are currently no approved targeted therapies.
ALKIVIA Shows Sustained Treatment Benefit
The ALKIVIA Phase 3 study demonstrated that the treatment effect emerged early and remained sustained throughout the 52-week treatment period. In the combined IMNM and DM population, improvements with efgartigimod were observed as early as Week 4 and remained statistically significant through the full year of treatment, including during corticosteroid tapering. Prespecified analyses also showed a statistically significant improvement in the IMNM population, where patients receiving efgartigimod achieved a mean TIS of 45.05 compared with 30.24 for placebo, corresponding to a 14.8-point improvement (p=0.0048). In DM, the mean TIS was 51.51 versus 36.96, representing a 14.5-point numerical improvement, although statistical significance was not reached in the smaller subgroup. The treatment effect extended across the six core measures contributing to TIS, including muscle strength, physical function and overall disease activity, while DM patients also showed improvement in skin disease activity.
Phase 3 Data Strengthen Efgartigimod Development
The ALKIVIA results are particularly relevant because autoimmune myositis remains an area of significant unmet medical need, with treatment largely relying on corticosteroids and broad immunosuppressive therapies. According to argenx, approximately 100,000 people in the United States live with autoimmune myositis, including approximately 20,000 with IMNM and 40,000 with DM. The company is developing efgartigimod based on the role of pathogenic IgG autoantibodies in autoimmune disease. Efgartigimod is designed to selectively block the neonatal Fc receptor (FcRn), reducing circulating IgG autoantibodies. The global ALKIVIA study enrolled 264 patients across IMNM, DM and polymyositis, with the Phase 3 portion enrolling 175 patients and incorporating a protocol-mandated corticosteroid taper. The positive topline results provide clinical evidence supporting continued development of efgartigimod in autoimmune myositis, with detailed findings expected to be presented at an upcoming medical meeting.
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argenx Expands Autoimmune Disease Pipeline
The ALKIVIA outcome adds another potential indication to the broader development strategy for efgartigimod, which is already marketed under the VYVGART and VYVGART Hytrulo brands for certain autoimmune conditions. The therapy is designed around FcRn blockade, an approach intended to reduce disease-driving IgG autoantibodies while preserving other components of immune function. argenx continues to evaluate efgartigimod in additional autoimmune diseases, including Sjögren’s disease and systemic sclerosis, while maintaining its broader immunology innovation strategy. The company said the ALKIVIA findings represent the first Phase 3 study to demonstrate statistically significant and clinically meaningful improvement in disease activity in IMNM, a subtype with no approved therapy. For cGxP.wire, the key development is the successful Phase 3 endpoint, the sustained treatment response over 52 weeks, and the potential expansion of targeted FcRn-based treatment into autoimmune myositis.
Source:argenx, press relese
