To describe the clinical effectiveness and side effects of subcutaneous efgartigimod use in 3 patients with acetylcholine receptor-positive generalized myasthenia gravis (AChR +ve gMG).

There is currently limited data describing the clinical experience of subcutaneous efgartigimod use in AChR +ve gMG patients previously administered intravenous efgartigimod.

This is a retrospective chart review of 3 patients with AChR +ve gMG who were transitioned to subcutaneous efgartigimod after 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 were reported. An improvement in MG-ADL of 2 or more was considered clinically meaningful.

A total of 3 patients (M:1, F:2) with a mean age of 50.33 (± 5.51) were included in this cohort. All patients had a clinically meaningful reduction (≥ 2-point change) in MG-ADL after completion of the first cycle of IV efgartigimod (mean pre-efgartigimod 8.33 [±0.58] versus post- IV efgartigimod cycle one 6.00 [±0]). Clinically meaningful improvement in MG-ADL was observed after cycle 2 in 67% (2/3) of patients (mean post- IV efgartigimod cycle two 4.33 [±0.58]). Patients were then transitioned to subcutaneous efgartigimod 4 weeks after cycle 2 of IV efgartigimod. The reason for change was IV access issues in 2 patients and preference for shorter infusion time in 1 patient. A further 2 or more-point improvement in MG-ADL was achieved in two patients after subcutaneous efgartigimod administration. One patient maintained the improvement in MG-ADL that was noted with IV administration. No side effects were reported.

Subcutaneous efgartigimod maintained or improved the clinically meaningful changes in MG-ADL that had been achieved with IV efgartigimod in this cohort of AChR +ve gMG patients.