Efgartigimod for treating Guillain-Barré syndrome with poor response to intravenous immunoglobulin: a case report.

Background: Guillain-Barré syndrome (GBS) is a peripheral neuropathy mediated by immunoglobulin G (IgG) autoantibodies, which can cause acute flaccid paralysis. Miller-Fisher syndrome (MFS) is a variant of GBS, and in some cases, MFS may overlap with GBS (MFS-GBS overlap syndrome), potentially delaying the disease's progression. Apart from intravenous immunoglobulin (IVIg) and plasma exchange (PLEX), which are currently the clinical standard of care. However, at least 20-30% of patients develop acute respiratory failure during or shortly after IVIg or PLEX, and about 3-7% of patients die. Efgartigimod is an antagonist that targets the neonatal Fc receptor (FcRn) and shows promise in the treatment of GBS.

Case presentation: We present a case with MFS-GBS overlap syndrome who tested positive for serum ganglioside IgG antibodies. Despite completing a prescribed course of IVIg medication, the patient's symptoms continued to worsen, and she eventually developed respiratory failure. Subsequently, efgartigimod was used for treatment at a dose of 800 mg, administered four times in total. The patient's symptoms were relieved, leaving only external ophthalmoplegia. Additionally, using efgartigimod caused a gradual drop in the serum IgG level. This treatment regimen is the first reported.

Conclusion: For MFS-GBS overlap syndrome patients with poor IVIg response, we discovered that sequential treatment with efgartigimod (800 mg, four doses) was safe, effective, and could reduce the course of the disease. Efgartigimod is anticipated to represent a significant advancement in treating GBS through ongoing, thorough basic and clinical research.