2026 American Academy of Neurology Abstract Website

Objective:

The objective is to analyze the impact of tocilizumab on seizure frequency in patients with autoimmune encephalitis associated epilepsy (AEAE).

Background:

Tocilizumab, an IL-6r monoclonal antibody, is traditionally used in treatment of rheumatoid arthritis and SLE due to its critical role in B and T cell stimulation. Recently tocilizumab has emerged as an effective third-line therapy in refractory autoimmune encephalitis. Data on its use in AEAE is lacking.

Design/Methods:

A retrospective chart review of 10 adult subjects with AEAE (GAD 65+, Anti-Hu, NORSE, and seronegative) was conducted to compare seizure frequencies before and after the start of tocilizumab treatment (162 mg SC every 1-2 weeks). Concomitant changes to antiseizure medications (ASMs) and immunotherapy (IT) were also recorded.

Results:

Five out of the ten patients were responders to tocilizumab, with greater than 50% seizure reduction at 4-6 months post tocilizumab initiation. Median seizure reduction across all patients was 25% (IQR 0-75.5%). Two of seven of the patients with anti-GAD 65 AEAE had a 71% and 83% decrease in seizure frequency, four patients had no change, and one patient had an increase of 44%. The other responders had ANNA-1 AEAE (50% seizure reduction), post-cryptogenic NORSE epilepsy (80% seizure reduction), and seronegative AEAE (53% seizure reduction). Of the patients on concomitant immunotherapy (rituximab) or corticosteroids at the time of tocilizumab start, three of four had no change or an increase in seizure frequency, while one had a reduction of 50%. Antiseizure medications were not concomitantly adjusted during this time frame.

Conclusions:

Tocilizumab can reduce seizures in some patients with AEAE, but in one case increased seizures. Concomitant administration of immunotherapy and antiseizure medication changes may contribute to changes in seizures. IL-6 upregulation may be a target for disease-targeted interventions in AEAE.