Heterogeneous response to efgartigimod in real-world experience with myasthenia gravis: Predictors and treatment strategies.

Efgartigimod is an established therapy for acetylcholine receptor antibody-positive generalized myasthenia gravis, yet real-world data on long-term overall responsiveness, response patterns, steroid-sparing effects, bridging therapy use, and predictors of benefit remain limited. In this multicenter retrospective study, we evaluated 46 patients treated across seven tertiary centers between April 2022 and March 2025, collecting demographic, clinical, therapeutic, and outcome data. Patients received 193 treatment cycles (mean 4.3 per patient) with a mean inter-cycle interval of 9.8 weeks. Following the first cycle, 86.9 % achieved a ≥2-point improvement in the Myasthenia Gravis Activities of Daily Living scale and 43.5 % reached minimal symptom expression (MSE); overall, 52.2 % achieved MSE at least once during follow-up. Nonetheless, 35.9 % discontinued efgartigimod due to insufficient efficacy, underscoring heterogeneous and often non-durable responses. Among 29 patients on prednisone, 58.6 % achieved a significant dose reduction (30.9-16.8 mg/day, p = 0.001), with shorter disease duration predicting successful tapering. Bridging therapy was successful in 5 patients, particularly those receiving azathioprine or mycophenolate (p = 0.040), supporting its utility during transitions to slower-acting immunosuppressants. Adverse events occurred in 21.7 % of patients, were generally mild, and led to discontinuation in only one case. Overall, efgartigimod was effective and well tolerated, but treatment responses varied, and cycle-based regimens frequently failed to sustain benefit. The observed steroid-sparing effect and predictors of response highlight the need for personalized treatment strategies and prospective studies to refine long-term use and optimize patient selection.