Reduction in oral glucocorticoid use after efgartigimod initiation in clinical practice among patients with generalized myasthenia gravis

This study evaluated changes in oral glucocorticoid (GC, prednisone equivalent) use among patients with generalized myasthenia gravis (gMG) previously using chronic GCs, who initiated and continued efgartigimod for ≥12 months, identified retrospectively from a US claims database. Myasthenia Gravis Activities of Daily Living (MG-ADL) scores were retrieved from a patient support program. The primary outcome was GC average daily dose (GC ADD) assessed during the 3 months before and 3, 6, 9, and 12 months after efgartigimod initiation. Overall, 266 patients were included (mean age: 59.8 years; 45 % female). Mean (95 % CI) GC ADD was significantly reduced at 3 (14.3 [12.6, 16.0] mg/day), 6 (13.4 [11.5, 15.4] mg/day), 9 (11.6 [10.0, 13.3] mg/day), and 12 (10.2 [8.8, 11.6] mg/day) months post-efgartigimod initiation compared to baseline (17.9 [15.7, 20.1] mg/day) (p < 0.001). At 12 months, 66 % (n = 176/266) reduced steroid dose. Among those, 68 % and 51 % achieved ≥50 % and ≥ 75 % ADD reduction, respectively. The proportion of patients using GC ADD of ≤5 mg/day increased from 13 % at baseline to 42 % at 12 months. Among 126 patients (47 %) who had MG-ADL scores available, there was a significant reduction from baseline in best follow-up mean (95 % CI) MG-ADL (from 7.9 [7.2, 8.5] to 3.1 [2.6, 3.6]), while mean GC ADD remained significantly reduced (p < 0.05). Thus, in patients with gMG using chronic GCs at baseline, GC use substantially reduced following efgartigimod initiation, while retaining improved MG-ADL scores, underscoring the potential steroid-sparing effect of efgartigimod in gMG treatment.