Evaluation of Responsiveness to Reduced-dose Rituximab in Corticotropin/IVIg/Rituximab Combination Immunotherapy for Opsoclonus-Myoclonus Syndrome

Publication date: Available online 18 May 2018
Source:Pediatric Neurology
Author(s): Michael R. Pranzatelli, Elizabeth D. Tate, Nathan R. McGee, Craig A. MacArthur
BACKGROUNDRituximab (anti-CD20) has been used as B cell-targeted intervention to treat opsoclonus-myoclonus syndrome (OMS). Due to isolated reports of chronic hypogammaglobulinemia and B lymphopenia following rituximab in several disorders, and rapid B cell depletion after a few doses, we reduced the dosage 20% in our clinical practice.METHODSIn this IRB-approved retrospective study, 32 children with OMS and cerebrospinal fluid (CSF) B cell expansion had received front-loaded adrenocorticotropic hormone (ACTH1-39), intravenous immunoglobulin (IVIg), and rituximab combination immunotherapy ("FLAIR-CI") for de novo OMS. Parametric statistical analysis compared 10 children receiving 1200 mg/m² of rituximab (300 mg/m² x 4) and 22 receiving 1500 mg/m² (375 mg/m² x 4). Clinical response had been video-documented and scored by a blinded observer.RESULTSIn both groups, motor severity (total score) lessened by ≥ 76% and CSF B cells were similarly depleted (≥ 95%) 6 months after treatment. None of the treated patients remained unable to walk independently. Serum IgM depletion was analogous in the 1200 mg/m² (-73%) and 1500 mg/m² group (-64%). The relapse frequency was similar in both groups. Side effects were principally steroidal, tolerable, and transient. Circulating B cell repopulation was comparable.CONCLUSIONSThe reduced-dose of rituximab in FLAIR-CI was as effective and well- tolerated as the standard dose, and provided rapid, early therapeutic intervention in OMS. Pending a long-term prospective study, these are proof-of-concept data in support of challenging the dose of rituximab in various disorders, which may have different dose requirements.



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