Rituximab for Pediatric Central Nervous System Inflammatory Disorders in Alberta, Canada.

Background: Rituximab is a B-cell-depleting monoclonal antibody whose off-label use is funded in Alberta by the Short-Term Exceptional Drug Therapy (STEDT) program. This study describes the use of rituximab for pediatric central nervous system (CNS) inflammatory disorders in Alberta. Methods: Rituximab applications for CNS inflammatory indications in patients < 18 years of age were identified from the STEDT database between January 1, 2012 – December 31, 2019. Patient information was linked to other provincial datasets, including the Discharge Abstract Database, Pharmaceutical Information Network, and provincial laboratory data. Analysis was descriptive. Results: 51 unique rituximab applications were identified, of which 50 were approved. New applications increased from one in 2012 to a high of 12 in 2018. The most common indication was autoimmune encephalitis (other than anti-NMDA receptor encephalitis; n=20, 39%). Most children were approved for a two-dose (n=33, 66%) or four-dose (n=16, 32%) induction regimen. Physician-reported outcomes were available for 24 patients, of whom 14 (58%) were felt to have fully met outcome targets. Conclusions: The use of rituximab for pediatric CNS inflammatory disorders has increased, particularly for the indication of autoimmune encephalitis. This study identified significant heterogeneity in dosing practices and laboratory monitoring, as well as regional disparities in use.