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Published on: February 20, 2018
Randomized phase 2 study of FcRn antagonist efgartigimod in generalized myasthenia gravis
James F Howard1, Vera Bril1, Ted M Burns1
1From the Department of Neurology (J.F.H.), University of North Carolina, Chapel Hill; Krembil Neuroscience Centre (V.B.), University Health Network, Toronto, Canada; Department of Neurology (T.M.B.), University of Virginia, Charlottesville; Department of Neuroimmunology and Neuromuscular Diseases (R.M.), Fondazione Istituto Neurologico Carlo Besta, Milan, Italy; Department of Neurology (B.M.), Wroclaw Medical University; Department of Neurology (A.S.), Jagiellonian University Medical College, Cracow, Poland; Department of Neurology (S.B.), University of Southern California, Keck School of Medicine, Los Angeles County Medical Center; Department of Neurology (F.J.R.D.R.G.), La Paz University Hospital, Neuroscience Area of IdiPAZ Health Research Institute, Autonoma University of Madrid, Spain; Neuroimmunology Unit, Department Clinical Neuroscience (F.P.), Karolinska Institutet, Karolinska University Hospital (Solna), Stockholm, Sweden; USC Neurologia (M.R.), USS Malattie Autoimmuni-Centro Sclerosi Multipla, Azienda Socio Sanitaria Territoriale Papa Giovanni XXIII, Bergamo, Italy; Neurology Department (P.V.D.), University Hospitals Leuven; Laboratory of Neurobiology (P.V.D.), Department of Neuroscience, KU Leuven and Center for Brain & Disease Research, VIB, Leuven, Belgium; Department of Neurology (T.V.), University of South Florida, Morsani College of Medicine, Tampa; Institute of Neurology (A.E.), Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Università Cattolica del Sacro Cuore, Rome, Italy; Neurology Department (M.F.), The Ohio State University, Columbus; Department of Neurology (T.M.), University of California, Irvine; Department of Molecular and Cellular Medicine (E.S.W.), Texas A&M University Health Science Center, College Station; argenx BVBA (T.D., P.U., K.V., A.G., H.d.H., N.L.), Zwijnaarde, Belgium; and Department of Neurology (J.J.G.M.V.), Leiden University Medical Center (LUMC), the Netherlands.
Objective:
To investigate safety and explore efficacy of efgartigimod (ARGX-113), an anti-neonatal Fc receptor immunoglobulin G1 Fc fragment, in patients with generalized myasthenia gravis (gMG) with a history of anti-acetylcholine receptor (AChR) autoantibodies, who were on stable standard-of-care myasthenia gravis (MG) treatment.
Methods:
A phase 2, exploratory, randomized, double-blind, placebo-controlled, 15-center study is described. Eligible patients were randomly assigned (1:1) to receive 4 doses over a 3-week period of either 10 mg/kg IV efgartigimod or matched placebo combined with their standard-of-care therapy. Primary endpoints were safety and tolerability. Secondary endpoints included efficacy (change from baseline to week 11 of Myasthenia Gravis Activities of Daily Living, Quantitative Myasthenia Gravis, and Myasthenia Gravis Composite disease severity scores, and of the revised 15-item Myasthenia Gravis Quality of Life scale), pharmacokinetics, pharmacodynamics, and immunogenicity.
Results:
Of the 35 screened patients, 24 were enrolled and randomized: 12 received efgartigimod and 12 placebo. Efgartigimod was well-tolerated in all patients, with no serious or severe adverse events reported, no relevant changes in vital signs or ECG findings observed, and no difference in adverse events between efgartigimod and placebo treatment. All patients treated with efgartigimod showed a rapid decrease in total immunoglobulin G (IgG) and anti-AChR autoantibody levels, and assessment using all 4 efficacy scales consistently demonstrated that 75% showed a rapid and long-lasting disease improvement.
Conclusions:
Efgartigimod was safe and well-tolerated. The correlation between reduction of levels of pathogenic IgG autoantibodies and disease improvement suggests that reducing pathogenic autoantibodies with efgartigimod may offer an innovative approach to treat MG.
Classification Of Evidence:
This study provides Class I evidence that efgartigimod is safe and well-tolerated in patients with gMG.
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