2026 American Academy of Neurology Autoimmune Abstract Website

Antonia Lefter¹, Tania Kumpfel², Jacqueline Palace³, Zsolt Illes⁴, Friedemann Paul⁵, Georgina Arrambide⁶, Orhan Aktas⁷, Ayse Altintas⁸, Thais Armangue⁹, Gregor Brecl Jakob¹⁰, Andrew Chan¹¹, Kumaran Deiva¹², Jelena Drulovic¹³, Katrin Gross-Paju¹⁴, Mario Habek¹⁵, Maria Hastermann¹⁶, Ellen Iacobaeus¹⁷, Maciej Jurynczyk¹⁸, Ming Lim¹⁹, Sara Mariotto²⁰, Cecilia Rajda²¹, Ernestina Santos²², Aksel Siva²³, Romain Marignier²⁴, Paulus Rommer²⁵, Barbara Willekens²⁶
¹Translational Sciences Research Group, Faculty of Medicine and Health Sciences, University of Antwerp, ²Ludwig Maximilian University of Munich, ³John Radcliff Hospital Oxford Univeristy Hospitals Trust, ⁴Odense University Hospital, University of Southern Denmark, ⁵Charite Universitatsmedizin in Berlin, ⁶Cemcat, Vall d´Hebron University Hospital, ⁷Neurologische Klinik, ⁸Koc University School of Medicine, ⁹IDIBAPS-HClinic, ¹⁰University Medical Center Ljubljana, University of Ljubljana, ¹¹Bern University Hospital, University of Bern, ¹²Bicêtre Hospital, Assistance Publique-Hôpitaux de Paris, Paris-Saclay University Hospitals, ¹³University Clinical Center of Serbia, ¹⁴Laane-Tallinna Keskhaigla, ¹⁵University Hospital Center Zagreb, School of Medicine, University of Zagreb, ¹⁶Max Delbrueck Center for Molecular Medicine and Charité-Universitätmedizin, ¹⁷Karolinska Institute, Karolinska University Hospital, ¹⁸Institute of Psychiatry and Neurology, ¹⁹Evelina London Children`s Hospital at Guy`s and St Thomas` National Health Service Foundation Trust, ²⁰Neurology Unit, University of Verona, ²¹Department of Neurology, Faculty of Medicine, University of Szeged, ²²Santo Antonio University Hospital Centre, University of Porto, ²³Istanbul University Cerrahpasa School of Medicine, ²⁴Lyon University Hospital, ²⁵AKH Wien / Univ. Klinik Fuer Neurologie, ²⁶Antwerp University Hospital

Objective:

Identification of real-world clinical practice strategies with rituximab regimes and immunoglobulin replacement therapy (IgRT) in neuromyelitis optica spectrum disorder (NMOSD) among European experts in rare neuroinflammatory diseases (NID).

Background:

Infections are frequent adverse events associated with B cell depleting therapies in NMOSD. Clinical practice involving rituximab de-escalation strategies and IgRT is diverse worldwide.

Design/Methods:

A modified Delphi panel study was conducted from June 2024 until September 2025. Panel members were experts in NID who attended the 2^nd and 3^rd NMOSD/MOGAD Case-based European Forums held in Tallinn and Prague. The initial voting round featured 8 questions on individual practice with rituximab and 8 questions about IgRT use in AQP4-IgG-positive and double-seronegative NMOSD.

Results:

Seventeen experts in rare NID participated in round 1. Dosing regimens for rituximab vary across countries. Over a third of panelists do not implement either rituximab dose reduction (DR) or extended interval dosing (EID) in NMOSD until infections occur. The most used rituximab DR regime to prevent infections is 500 mg once 6 monthly (47%), considering a standard maintenance regime of 1000 mg once 6 monthly. EID is largely based on CD19+ B cell counts (~65%). Patient`s age, comorbidities, baseline serum immunoglobulin G (IgG) level and prior immunosuppression were considered main risk factors for hypogammaglobulinemia and/or infections driving the decision to perform rituximab DR and/or EID. Immunoglobulin levels are monitored by 76% before start of therapy and 6 monthly thereafter. IgRT to treat secondary hypogammaglobulinemia is based on serum IgG levels (53%) and scheduled 4 weekly (35%) with 0.4 g/kg (65%). The target serum IgG level is 5 g/L for >50% panelists, but varies.

Conclusions:

There are differences in rituximab dosing regimens and IgRT regarding infectious risk management strategies in NMOSD. Notably, there is a lack of data on such strategies, and more research is warranted to inform evidence-based clinical practice recommendations.