argenx reports positive Phase 3 ALKIVIA results for efgartigimod in autoimmune myositis

argenx SE announced on August 17, 2026 that its Phase 3 ALKIVIA trial of efgartigimod (marketed as VYVGART Hytrulo) met its primary endpoint in adults with autoimmune myositis. The company said the study met the primary endpoint of mean Total Improvement Score (TIS) at Week 52 in the combined study population of IMNM and DM patients, with a p-value of 0.0011.¹

Across the combined immune-mediated necrotizing myopathy (IMNM) and dermatomyositis (DM) group, patients on efgartigimod showed a 15.4-point greater improvement in mean TIS at Week 52 compared with placebo, at 47.95 versus 32.56.¹ The company noted that benefits over placebo emerged as early as Week 4 and were sustained through the full year of treatment, even with steroid tapering.¹

Looking at the subtypes separately, the IMNM group also met the primary endpoint (p=0.0048), showing a 14.8-point improvement over placebo, 45.05 versus 30.24.¹ In the smaller DM cohort, a 14.5-point improvement was seen (51.51 vs 36.96), though this did not reach statistical significance, with a p-value of 0.1093.¹

On safety, argenx said efgartigimod was well-tolerated, with a safety profile consistent with prior studies and the known profile of the drug.¹

The ALKIVIA study design included a global, randomized, double-blind, placebo-controlled Phase 2/3 trial that enrolled 264 patients with active disease on background treatment.¹ The Phase 3 portion alone enrolled 175 patients and included a mandated corticosteroid taper throughout the study.¹

argenx said detailed results will be presented at a future medical meeting.¹ The company hosted an investor call on the results the same day the release was issued.