To evaluate the efficacy, safety, and tolerability of 10 mg/kg intravenous efgartigimod administered in a fixed-cycle regimen (4 once-weekly infusions with a 4-week intertreatment period) or continuous dosing regimen (every 2 weeks).
Individualized cyclic administration of efgartigimod, a human immunoglobulin G1 Fc-fragment that blocks the neonatal Fc receptor, was well tolerated and efficacious in the ADAPT/ADAPT+ phase 3 trials of patients with generalized myasthenia gravis (gMG). The phase 3b ADAPT NXT study (NCT04980495) is investigating the efficacy and safety of efgartigimod in both continuous and fixed-cycle regimens.
Adult participants with acetylcholine receptor antibody positive gMG who had a Myasthenia Gravis Activities of Daily Living (MG-ADL) total score of ≥5 (with >50% of the score due to nonocular symptoms), and on a stable dose of ≥1 concomitant gMG treatment were recruited. After a 3-week induction period during which all randomized participants received a total of 4 efgartigimod infusions, 69 participants were randomized 3:1 to either continuous or fixed-cyclic dosing regimens for the initial 21-week comparison period. Thereafter, participants in the fixed-cycle arm received a final cycle before being rolled over to continuous every 2 week dosing while participants in the continuous dosing arm maintained every 2 week dosing. Participants were followed for an additional 105 week extension period, and participants who maintained clinical improvement had the option to reduce dosing frequency to every 3 weeks.
ADAPT NXT will provide important data on different treatment regimens, which will allow for further individualization of treatment with efgartigimod.