The purpose of this study is to describe the clinical experience, including effectiveness and side effects, of intravenous efgartigimod use in 11 patients with acetylcholine receptor-positive generalized myasthenia gravis (AChR +ve gMG).

This is a retrospective chart review of 11 AChR +ve gMG patients who were treated with at least 2 cycles of IV efgartigimod and had both pre- and post- efgartigimod myasthenia gravis activities of daily living (MG-ADL) scores. Information regarding patient demographics, concomitant treatment(s), MG clinical history, and adverse events was reported. An improvement in MG-ADL of 2 or more was considered clinically meaningful.

A total of 11 patients (M:5, F:6) with a mean age of 57.36 (± 18.72) were included in this cohort. A total of 73% (8/11) of patients had a clinically meaningful reduction (≥ 2-point change) in MG-ADL after completion of the first cycle of efgartigimod. Eighty-two percent (9/11) had a clinically meaningful reduction in MG-ADL after cycle 2 (mean pre-efgartigimod 9.27 [± 1.62] versus post-efgartigimod 6.1 [±2.33]). One patient achieved minimal symptom expression after cycle 2. In 3 patients, prednisone dose (mean pre-efgartigimod dose 25.91 mg [±5.39]) was tapered after cycle 2 (mean dose reduction 6.67 [±2.89]). Side effects were mild with one patient experiencing headache and one upper respiratory infection.

Efgartigimod led to clinically meaningful improvement in MG-ADL in 82% of AChR +ve gMG patients after two cycles with mild side effects. Prednisone dose was reduced in 3/11 patients by an average of 6.67 (±2.89).