Comparison of Efficacy and Safety in Patients Switching From MabThera® to Rixathon® in Relapsing-Remitting Multiple Sclerosis

Inclusion Criteria: * Diagnosed with multiple sclerosis (MS) according to the 2017 McDonald criteria (or previous applicable versions at the time of diagnosis). * Treated with MabThera® (rituximab originator) at the Department of Neurology, Uppsala University Hospital before January 1, 2023. * Switched to Rixathon® (rituximab biosimilar) for MS treatment starting January 1, 2023. * Registered in the Swedish MS Registry (SMSreg) with available clinical data. * At least one clinical follow-up visit recorded before the switch and one after the switch. * Available plasma neurofilament light chain (pNfL) measurement and/or brain MRI scan during the study period. Exclusion Criteria: * No recorded clinical follow-up visit after switching to Rixathon®. * Switched to Rixathon® but later discontinued treatment within 3 months for reasons unrelated to disease activity (e.g., administrative, insurance, or non-medical reasons). * Participation in another interventional clinical trial affecting MS outcomes during the study period. * Diagnosis of other major neurological diseases that could confound MS outcomes (e.g., stroke, CNS infection, or primary CNS tumors). * Lack of consent for research use of data in the Swedish MS Registry.