Good news for a trickier subset of myasthenia gravis patients. Data from the open-label period of the ADAPT SERON trial show that IV efgartigimod (Vyvgart) maintained meaningful improvements in daily functioning through 52 weeks in patients with generalized myasthenia gravis (gMG) who lack anti-acetylcholine receptor (AChR) antibodies — a group that historically had fewer treatment options. The findings were presented at the 2026 American Association of Neuromuscular and Electrodiagnostic Medicine meeting.

A standout insight: more treatment cycles led to better outcomes. Researchers observed increasing proportions of patients achieving minimal symptom expression (an MG-ADL score of 0 or 1) with each successive cycle — a pattern that suggests clinicians may need to give this population more time before concluding a treatment isn't working, unlike the 2–3 cycle rule of thumb used for AChR-positive patients.

Key Takeaways:

• Patients maintained ~5-point mean improvement in MG-ADL scores through week 52
• In the double-blind phase, efgartigimod outperformed placebo by 1.46 points in MG-ADL reduction (P=0.007)
• 80.5% of participants remained in the open-label phase as of June 2026
• The FDA expanded efgartigimod's indication in May 2026 to cover all gMG patients, regardless of antibody status

Why it matters: About 20% of gMG patients lack AChR antibodies, leaving them in a therapeutic gray zone. These results reinforce efgartigimod's role across gMG subtypes and suggest that pathogenic IgGs may be a common driver of disease — opening the door to broader, antibody-agnostic treatment strategies.