Efgartigimod Shows Rapid Short-Term Responses in Juvenile MG Cohort
Key Takeaways
- Improvement was observed by week 1 and continued through week 4 across the short observation window.
- Minimal symptom expression was reported in 66.7% (8/12) of evaluable patients by week 4.
- Patients remained on background immunosuppressive therapy, and short-term monitoring showed no treatment-related adverse events with a significant fall in serum IgG.
This retrospective multicenter case series included 17 patients with juvenile myasthenia gravis who were younger than 18 years and treated at 12 Chinese centers. Efgartigimod was given at 10 mg/kg once weekly, and one treatment cycle comprised four weekly doses. Assessments compared baseline W0 with weekly follow-up at W1 through W4 using MG-ADL, QMG, and MGC measures.
The cohort had a median disease duration of 23 months, included 14 females and 3 males, and largely represented anti-AChR-positive patients in MGFA class II–V. Sixteen patients were treated for acute exacerbation, and one was treated for insufficient response.
Efficacy signals appeared early, with clinically meaningful improvement in 70.6% (12/17) at W1 and 73% at W2. Compared with baseline, MG-ADL fell by 30% at W1 and 87.6% at W4, while QMG fell by 30.1% and 71.8%. Ocular, limb, bulbar, and respiratory muscle groups also showed progressive improvement across follow-up. Patients with refractory juvenile myasthenia gravis also improved by week 4. Overall, the response pattern moved from early gains toward stronger week 4 improvement.
All patients continued standardized immunosuppressive therapies, including steroids and other immunosuppressants, although patients received between one and four doses according to symptom relief and economic considerations. Six patients did not complete one full cycle for those reasons.
No treatment-related adverse events were reported, including medication-related allergic reactions, infections, or serious adverse events, and no deaths attributable to adverse events were observed.
By W4, serum IgG decreased significantly to 6.57 versus 9.786 at baseline, with p=0.0203, while IgM, IgA, total cholesterol, and albumin showed no significant differences. One patient developed COVID-19-associated myasthenic crisis and recovered after steroid pulse therapy while continuing efgartigimod, while another with prior hepatitis C showed no liver dysfunction or acute viral reactivation.
The authors emphasized several limits on interpretation, including the retrospective uncontrolled design and small sample size. They also noted short follow-up, an adolescent-only cohort, and the absence of data on glucocorticoid or other immunosuppressant reduction. Most patients did not undergo repeat AChR-Ab testing at week 4, and exposure duration varied because some stopped early after symptom relief or for cost.