Efgartigimod in patients with generalized myasthenia gravis: ADAPT and ADAPT+

James F. Howard, Jr., MD, FAAN, University of North Carolina School of Medicine, Chapel Hill, NC, comments on interim results from ADAPT+ (NCT03770403), an open label extension of ADAPT (NCT03669588). ADAPT was a multinational, double-blinded study investigating efgartigimod in patients with generalized myasthenia gravis. Efgartigimod is a small Fc fragment engineered to bind to the neonatal Fc receptor, which the immunoglobulin IgG usually binds to. Consequently, IgG cannot bind and is destroyed by the lysosome. The study looked at the efficacy, reproducibility, and durability of efgartigimod, while the open label extended these observations for a prolonged time period. Observations included a rapid improvement after the first infusion of efgartigimod, reaching a peak within one week of the fourth infusion. The study also showed repeatability, as patients achieved similar reductions in IgG (60%) and circulating antibody (58-59%) during repeated treatments. A substantial durability of the response was seen, as 50% of patients achieved an improvement lasting over eight weeks. Prof. Howard also mentions the nominal safety profile of efgartigimod, whereby there was only a slight increase in mild infections in the treated arm. Assessing the long term need of efgartigimod infusions, it seemed that individuals required less than five courses of infusion per year on average. This interview took place at the American Academy of Neurology 2022 Congress in Seattle, WA.