AIE is a severe neurological disorder caused by autoimmune attack on central nervous system proteins. Depending on the immune-driver, the clinical syndrome may include seizures, psychiatric disturbance, cognitive/linguistic decline, impaired consciousness, motor dysfunction, brainstem dysfunction, and/or autonomic instability. Observational evidence indicates improved outcomes with standard immunotherapy; however, many patients experience partial responses, relapse or long-term sequelae. Several AIE subtypes are associated with pathogenic IgG autoantibodies. FcRn blockade reduces circulating IgG levels, providing a mechanistic basis for further study in antibody-mediated disease.

A targeted literature review identified observational cohorts of patients with AIE treated off-label with efgartigimod. Aggregate efficacy outcomes, including modified Rankin scale (mRS) and Clinical Assessment Scale for AIE (CASE) scores, were independently extracted by two researchers and meta-analyzed to derive real-world summary outcomes. Analyses were performed using the R meta package.

Five retrospective comparative studies of Chinese patients with extracellular antibody-mediated AIE (N= 320) were identified. Four included only anti-N-methyl-D-aspartate-receptor (NMDAR) encephalitis (N=198), while one included patients with mixed neuronal extracellular antibodies (N=122). Across reported follow-up windows (3–4, 7–8, and 12–15 weeks post-treatment initiation), studies reported changes from baseline in mRS and CASE scores among patients receiving immunotherapy including FcRn blockade. The meta-analyses enabled synthesis of outcome patterns across studies, highlighting both overall trends in clinical improvement and variability between cohorts, subtypes, and treatment strategies. Where pooling was feasible, estimates provided directional insight in treatment-related outcomes with efgartigimod while reflecting between-study heterogeneity in populations and treatment strategy.