Argenx: positive phase 3 trial in autoimmune myositis (p = 0.0011)
Argenx announced on August 17, 2026 positive primary results for its ALKIVIA phase 3 trial, which evaluated Vyvgart Hytrulo (efgartigimod) in adults with autoimmune myositis.
The group thus expands the potential scope of its flagship molecule, already commercialized in generalized myasthenia gravis and chronic inflammatory demyelinating polyradiculoneuropathy, toward an indication where no approved targeted treatment exists.
The trial meets its primary endpoint with statistical significance of p = 0.0011
The ALKIVIA study met its primary efficacy endpoint, with a p-value of 0.0011. This endpoint was based on the average Total Improvement Score at the end of a 52-week treatment period, measured across all treated patients and compared to placebo.
According to Argenx, the therapeutic benefit was rapid and sustained, with separation from placebo appearing early and maintained over a full year of treatment. The magnitude of clinical improvement was presented as comparable between the two studied subtypes, immune-mediated necrotizing myopathy (IMNM) and dermatomyositis (DM), with an effect observed in both muscle and skin measures.
A tolerability profile consistent with previous studies
Argenx indicates that efgartigimod was well tolerated by patients in the ALKIVIA study. The safety profile observed was presented as consistent with previous studies and with the known safety profile of the molecule.
The ALKIVIA trial was a global, randomized, double-blind, placebo-controlled phase 2/3 study involving 264 patients with autoimmune myositis (IMNM, DM, and PM). The phase 3 portion enrolled 175 patients and included a protocol-mandated gradual reduction in corticosteroids. Patients received weekly subcutaneous injections of efgartigimod or placebo, in a 1:1 randomization.
Continued evaluation in other rheumatologic diseases
According to the press release, approximately 100,000 people live with autoimmune myositis in the United States, of which approximately 20,000 have IMNM and approximately 40,000 have dermatomyositis. Up to 80% of patients report long-term disability despite treatment, with current management based on corticosteroids and broad-spectrum immunosuppressants.
Argenx specifies that efgartigimod continues to be evaluated as a potential treatment in other autoimmune rheumatologic diseases, including Sjögren's disease and systemic sclerosis. Detailed results from the ALKIVIA study will be presented at an upcoming medical congress.
