Long-term safety, tolerability, and efficacy of efgartigimod (ADAPT+): interim results from a phase 3 open-label extension study in participants with generalized myasthenia gravis

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  • Howard, James F.
    • Affiliation: School of Medicine, Department of Neurology
  • Bril, Vera
    • Other Affiliation: University of Toronto
  • Vu, Tuan
    • Other Affiliation: University of South Florida Morsani College of Medicine
  • Karam, Chafic
    • Other Affiliation: Hospital of the University of Pennsylvania,
  • Peric, Stojan
    • Other Affiliation: University of Belgrade
  • De Bleecker, Jan L.
    • Other Affiliation: Ghent University Hospital
  • Murai, Hiroyuki
    • Other Affiliation: International University of Health and Welfare
  • Meisel, Andreas
    • Other Affiliation: Charité – Universitätsmedizin Berlin
  • Beydoun, Said R.
    • Other Affiliation: University of Southern California
  • Pasnoor, Mamatha
    • Other Affiliation: University of Kansas Medical Center
  • Guglietta, Antonio
    • Other Affiliation: argenx
  • Van Hoorick, Benjamin
    • Other Affiliation: argenx
  • Steeland, Sophie
    • Other Affiliation: argenx
  • T’joen, Caroline
    • Other Affiliation: argenx
  • Utsugisawa, Kimiaki
    • Other Affiliation: Hanamaki General Hospital
  • Verschuuren, Jan
    • Other Affiliation: Leiden University Medical Center
  • Mantegazza, Renato
    • Other Affiliation: Fondazione Istituto Carlo Besta
  • The ADAPT+ Study Group
Abstract
  • Objective ADAPT+ assessed the long-term safety, tolerability, and efficacy of efgartigimod in adult participants with generalized myasthenia gravis (gMG). Methods ADAPT+ was an open-label, single-arm, multicenter, up to 3-year extension of the pivotal phase 3 ADAPT study. Efgartigimod was administered in treatment cycles of 4 intravenous infusions (one 10 mg/kg infusion per week). Initiation of subsequent treatment cycles was individualized based on clinical evaluation. Safety endpoints included incidence and severity of adverse events. Efficacy endpoints assessed disease severity using Myasthenia Gravis-Activities of Daily Living (MG-ADL) and Quantitative Myasthenia Gravis (QMG) scores. Results As of January 2022, 151 participants had rolled over to ADAPT+ and 145 had received ≥1 dose of efgartigimod, of whom, 111 (76.6%) were AChR-Ab+ and 34 (23.4%) were AChR-Ab−. Mean study duration (treatment plus follow-up) was 548 days, and participants received up to 17 treatment cycles, corresponding to 217.6 participant-years of exposure. In the overall population, 123 (84.8%) participants reported ≥1 treatment-emergent adverse event; most frequent were headache (36 [24.8%]), COVID-19 (22 [15.2%]), and nasopharyngitis (20 [13.8%]). Clinically meaningful improvement (CMI) in mean MG-ADL and QMG scores was seen as early as 1 week following the first infusion across multiple cycles in AChR-Ab+ and AChR-Ab− participants. Maximal MG-ADL and QMG improvements aligned with onset and magnitude of total IgG and AChR-Ab reductions. For AChR-Ab+ participants at any time point in each of the first 10 treatment cycles, more than 90% had a maximum reduction of ≥2 points (CMI) in MG-ADL total score; across the 7 cycles in which QMG was measured, 69.4% to 91.3% of participants demonstrated a maximum reduction of ≥3 points (CMI) in QMG total score. Many participants demonstrated improvements well beyond CMI thresholds. In AChR-Ab+ participants with ≥1 year of combined follow-up between ADAPT and ADAPT+, mean number of annualized cycles was 4.7 per year (median [range] 5.0 [0.5–7.6]). Conclusion Results of ADAPT+ corroborate the substantial clinical improvements seen with efgartigimod in ADAPT and support its long-term safety, tolerability, and efficacy, as well as an individualized dosing regimen for treatment of gMG. Clinical trial registrationhttps://classic.clinicaltrials.gov/ct2/show/NCT03770403, NCT03770403.
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  • In Copyright
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  • Attribution 4.0 International
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  • Frontiers in Neurology
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  • 14
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  • English
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  • 1664-2295
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  • Frontiers Media SA

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