[Pubmed] Long-term safety, tolerability, and efficacy of subcutaneous efgartigimod PH20 in generalized myasthenia gravis

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Front Neurol. 2026 Aug 21;17:1876344. doi: 10.3389/fneur.2026.1876344. eCollection 2026.

ABSTRACT

BACKGROUND: Efgartigimod is a human immunoglobulin (IgG1) antibody Fc fragment that reduces IgG levels through neonatal Fc receptor blockade. ADAPT-SC+ assessed the long-term safety, tolerability, and efficacy of subcutaneous (SC) efgartigimod PH20 in adult participants with generalized myasthenia gravis (gMG). Previously, ADAPT-SC demonstrated noninferiority of efgartigimod PH20 SC to intravenous efgartigimod.

METHODS: ADAPT-SC+ was a single-arm, multicenter, open-label extension study. Efgartigimod PH20 SC 1000 mg was administered in treatment cycles of 4 once-weekly injections, with timing of cycles individualized based on clinical evaluation. During the first year of the study, ≥4 weeks were required between cycles; in the second year and onward, participants consenting to a protocol amendment could have ≥1 week between cycles.

RESULTS: A total of 184 participants rolled over from ADAPT+ and ADAPT-SC, and 180 participants received ≥1 dose of efgartigimod PH20 SC. The mean (SD) treatment plus follow-up time was 2.6 (0.9) years, corresponding to 459.4 total participant years of follow-up, with a maximum of 33 treatment cycles. Overall, 169 (93.9%) participants experienced ≥1 treatment-emergent adverse event (TEAE), and the most frequent TEAEs were injection site reactions (ISRs; n = 83, 46.1%), COVID-19 (n = 53, 29.4%), and headache (n = 48, 26.7%). ISRs were mild or moderate in severity. No new safety signals were observed in participants with more frequent dosing (

Source: https://pubmed.ncbi.nlm.nih.gov/4269983 ... 5&v=2.20.1