Background: Nipocalimab is a highly specific, fully-human, aglycosylated anti-neonatal Fc receptor (FcRn) monoclonal antibody that selectively targets FcRn, reducing serum immunoglobulin G (IgG) including pathogenic autoantibodies in patients with generalized myasthenia gravis (gMG).
Objectives: To analyze long-term efficacy and safety of nipocalimab plus standard-of-care treatment in adolescents with gMG. vibrance-mg (NCT05265273) included seropositive adolescents (12─<18 years) with inadequately controlled gMG (MGFA Class II-IV) on stable standard-of-care therapy. Participants received nipocalimab (30-mg/kg IV loading dose, then 15-mg/kg IV every 2-weeks [Q2W]) for 24-weeks (Active-Treatment-Phase [AT]) followed by nipocalimab (15-mg/kg Q2W or 30-mg/kg Q4W) during long-term-extension (LTE). Endpoints included change in total serum IgG, Myasthenia Gravis Activities of Daily Living (MG-ADL), Quantitative Myasthenia Gravis (QMG), and safety. Results: Of 8 evaluable adolescents (7 females; mean [SD] age, 13.9 [1.89] years; 8 anti-AChR+), 7 completed AT (1 ongoing); 6 entered LTE (5 ongoing; 1 discontinued study [lack-of-efficacy]). Mean (SD) baseline MG-ADL/QMG total scores were 4.38 (2.264)/ 13.31 (4.131). IgG reductions were rapid and sustained: at Week 24 (n=7), median (interquartile range) pre-dose (minimal) % change-from-baseline in total IgG was -73.3% (-78.7%; -62.8%); mean (SD) change-from-baseline in MG-ADL/QMG were -2.57 (0.535)/ -4.93 (3.81). Efficacy was generally sustained through 44-weeks in LTE. In AT (average follow-up=24.16 weeks), 8/8 participants had ≥1 treatment-emergent adverse event (AE); there were no serious AEs/treatment discontinuations due to AE. In LTE, 4/6 participants had ≥1 treatment-emergent AE; there was 1 serious AE (MG) and 1 temporary treatment discontinuation (influenza). Conclusions: In adolescents with gMG, nipocalimab showed reductions in serum IgG, sustained disease control, and was well-tolerated.