Efgartigimod in Very-Late-Onset Generalized Myasthenia Gravis: A Real-World Study on Effectiveness and Safety

INTRODUCTION: This study evaluated the safety and effectiveness of efgartigimod in patients with Very-Late-Onset Generalized Myasthenia Gravis (VLOGMG), a population that often presents with more severe symptoms and limited treatment responses. METHODS: Forty-two patients aged ≥ 65 years were retrospectively included. Clinical assessments, including MG activities of Daily Living (MG-ADL), Quantitative Myasthenia Gravis (QMG) scores, prednisone dosage, laboratory data, and adverse events, were recorded at each follow-up. RESULTS: At week 4, 97.6% (41/42; 95% CI, 87.4-99.9) of patients were MG-ADL responders (≥ 2- point improvement). Notably, 83.3% (95% CI, 69.4-92.8) maintained response through week 12 (p < 0.001). Clinically meaningful improvement (CMI, ≥3-point QMG decrease) occurred in 97.6% of patients (41/42; 95% CI, 87.4-99.9), with a mean response time of 6.37 ± 5.46 days (95% CI, 4.63- 8.11). Minimal symptom expression (MSE, MG-ADL score of 0 or 1) was achieved in 45% (95% CI, 30-61%), 60% (95% CI, 44-74%), and 45% (95% CI, 30-61%) of patients at weeks 4, 8, and 12, respectively. Prednisone dosage was tapered from a median of 20 (20, 30) mg/day to 10 (5, 15) mg/day by week 12. Most patients (88.1%) had ≥ 1 comorbidity, and 61.9% had multimorbidity. Efgartigimod was well tolerated, without evidence of worsening of pre-existing conditions. DISCUSSION: Efgartigimod provided rapid symptom relief in older adults with VLOGMG and demonstrated steroid-sparing benefits across patients with various comorbidities. The high response rates and sustained improvement suggest that early use of fast-acting therapies may serve as a bridge to conventional long-term treatments. Larger prospective studies are warranted to confirm these findings. CONCLUSION: Efgartigimod is associated with clinical benefit in patients with VLOGMG, allowing corticosteroid reduction without compromising comorbidity stability. Early initiation may enable faster disease control and more durable responses.