To describe serious adverse events (SAE) in a large cohort of patients with CNS inflammatory disorders who were treated with rituximab (RTX) at two tertiary multiple sclerosis (MS) centers.

All patients who received at least one dose of RTX at the Rocky Mountain MS Center (RMMSC) at University of Colorado or New York University MS Care Center (NYUMSC) were identified. Patient charts were reviewed from RTX start date until 12 months post last RTX end date, or last ocrelizumab (OCR) infusion, if the patient transitioned to OCR. Data were abstracted from each chart using a case report form. Descriptive statistics were used to describe the sample group.

Five hundred twenty patients were identified (250 from RMMSC and 270 from NYUMSC), of whom 72 (13.9%) switched to OCR. Diagnoses were: 87% MS (57.1% relapsing, 30% progressive), 11.3% neuromyelitis optica spectrum disorder (NMOSD) and 2.5% other. Mean age at RTX start: 42 years, 70% female. Mean cumulative RTX dose was 4,731 mg (median: 3500 mg); mean dose of OCR was 1008mg; mean time of follow up on RTX/OCR was 32.2 months. During follow up, 25 patients (4.8%) experienced an infection requiring hospitalization, 3 patients (0.6%) were diagnosed with a new autoimmune disease, 5 patients (1%) with a new non-skin neoplasm, and 7 (1.3%) with a new non-superficial thrombosis. No patient experienced an infusion reaction requiring hospitalization. Seven patients (1.3%) died within 12 months of their last RTX dose, although, none were deemed related to RTX by the treating neurologist. No cases of PML were reported.