Efgartigimod alfa targets FcRn across three neuroimmune conditionsNew drug shows promise for rare autoimmune nerve conditions

Guillain-Barré syndrome (GBS) is an acute immune-mediated peripheral neuropathy characterized by rapidly progressive symmetric limb weakness and diminished tendon reflexes, which may be complicated by respiratory muscle paralysis in severe cases. Current first-line treatments primarily consist of intravenous immunoglobulin (IVIg) and plasma exchange (PE), but approximately 20% of patients have an incomplete response to standard therapies. Additionally, issues such as limited supply of blood products, adverse reactions, and contraindications may limit conventional treatments. Efgartigimod alfa is an engineered human IgG1 Fc fragment that targets the neonatal Fc receptor (FcRn) and competitively inhibits FcRn-mediated lgG recycling, thereby promoting the lysosomal degradation of circulating IgG, including pathogenic IgG autoantibodies, and reducing serum IgG levels. Intravenous efgartigimod alfa is approved for AChR antibody-positive generalized myasthenia gravis (gMG), whereas the U.S. approval for chronic inflammatory demyelinating polyneuropathy (CIDP) applies to the subcutaneous efgartigimod alfa/hyaluronidase co-formulation. Neither formulation is currently approved for GBS. Because IgG-mediated autoimmunity contributes to the pathogenesis of a subset of GBS, FcRn blockade provides a biologically plausible therapeutic strategy; however, its relevance may vary according to the underlying immunopathology. This narrative review summarizes the mechanistic rationale, preliminary clinical evidence, and available safety observations regarding efgartigimod in GBS, critically evaluates the limitations of the current evidence, and discusses unresolved questions and priorities for future research.