At the 2026 American Association of Neuromuscular and Electrodiagnostic Medicine meeting, researchers reported that efgartigimod (Vyvgart) continued to improve daily-living scores in generalized myasthenia gravis patients who test negative for acetylcholine receptor antibodies. The open-label extension of the ADAPT SERON trial showed a mean improvement of about 5 points on the Myasthenia Gravis Activities of Daily Living (MG-ADL) scale through 52 weeks.
The drug, an FcRn blocker that reduces circulating IgG autoantibodies, was initially approved for AChR-positive disease. After the double-blind portion showed benefits in anti-MuSK, anti-LRP4, and triple-seronegative patients, the FDA broadened the indication in May 2026 to cover all generalized myasthenia gravis.
The trial enrolled 119 participants without anti-AChR antibodies; 58 received efgartigimod. As of June 2026, 80.5% remained in the open-label phase. The safety profile was consistent with earlier trials, and the authors suggested that pathogenic IgG may drive the disease across subtypes, regardless of detectable autoantibody status.