Resolution of acute motor axonal neuropathy in a patient after treatment with efgartigimod: A case report

Abstract

Background: Guillain-Barré syndrome (GBS) is an acute autoimmune neuropathy characterized by progressive muscle weakness, often caused by immunoglobulin G (IgG) autoantibodies. There are several subtypes of GBS, of which acute motor axonal neuropathy (AMAN) is one of the most severe subtypes associated with axonal damage. It is well known that the current clinical standard of treatment is intravenous immunoglobulin (IVIg) and plasma exchange (PLEX), but some patients often show limited response or experience persistent disability. Efgartigimod, an Fc fragment of human IgG antibody, provides a way to target and reduce pathogenic IgG antibodies as a natural ligand Fc receptor (FcRn). The purpose of this study was to observe the therapeutic effect of efgartigimod on axonal GBS, which is expected to be a potential therapeutic method for GBS and AMAN. Methods: We present a case of a 58-year-old man diagnosed with AMAN, presenting with ascending symmetrical limb weakness, flaccid paralysis, and multiple cranial nerve palsies. Electromyography confirmed the axonal subtype of GBS. Despite receiving IVIg and PLEX, the patient showed suboptimal recovery. Subsequently, he was treated with efgartigimod at a dose of 10 mg/kg weekly for 4 weeks, demonstrating significant improvement in both clinical symptoms and electromyographic findings, with good tolerability. Result: This case highlights the potential efficacy and safety of a 4-dose efgart-igimod regimen in AMAN, particularly for patients with inadequate response to conventional therapies. By targeting FcRn and promoting IgG degradation, efgartigimod offers a novel mechanism to modulate the aberrant immune response underlying AMAN. Conclusion: Efgartigimod at a dose of 10 mg/kg weekly for 4 weeks demonstrated promising results in this case of AMAN. While further research is warranted, our findings suggest that efgartigimod may represent a valuable addition to the therapeutic armamentarium for AMAN and potentially other autoimmune neurological conditions. Well-designed clinical trials are crucial to confirm these findings and establish optimal treatment protocols for efgartigimod in AMAN.