Anakinra and tocilizumab in the chronic phase of febrile infection-related epilepsy syndrome (FIRES): Effectiveness and safety from a case-series

Purpose: There is scarce evidence of effective treatments for the chronic phase of Febrile infection-related epilepsy syndrome (FIRES). This study aimed to analyze the outcomes of treatment with anakinra and tocilizumab.

Methods: Retrospective study including patients receiving either anti-interleukin-1 (anti-IL-1, anakinra) or anti-IL-6 (tocilizumab) during the chronic phase of FIRES. We evaluated seizure outcomes, non-seizure comorbidities, and adverse events. Additionally, an indirect control group including patients during the chronic phase of FIRES non-treated with-IL therapies was evaluated.

Results: Five patients were included; three females. Median age at FIRES: 8 years (IQR: 6-10). Five patients received anakinra; one patient switched to tocilizumab after ineffectiveness. Median treatment duration was 9months (IQR: 7-20). While no patients became seizure-free, 20-50% reduction in seizure frequency was reported in 3/5 patients after 6 months with anakinra. Retention rate was 100% at 6 months and 40% at 12months. Three patients reported reduced seizure intensity and rescue medication needed, and better behavior/communication. Similar improvement was reported for the patient switching to tocilizumab. Patients with the best response received anti-IL a median of 9 years after acute phase. All discontinuations were due to ineffectiveness. There were none relevant adverse events apart from one patient presenting transient seizure aggravation. Nine patients were included in the control group; none of them showed relevant improvement in seizure outcomes or cognitive/behavioral comorbidities. Only one presented mild improvement in seizure frequency during the 6-months follow-up.

Conclusion: This study provides promising data on effectiveness/safety of anakinra and tocilizumab in the chronic phase of FIRES. These findings warrant prospective/larger studies.