To determine the clinical features, infection incidence, treatment persistence, and immunoglobulin levels in older adults treated with Ocrelizumab for MS.

Phase III clinical trials on Ocrelizumab for relapsing and primary progressive MS enrolled participants up to age 55 years.

Retrospective, observational cohort study at a single high-volume U.S. MS center of 300 randomly selected adults 55 years and above who received at least one dose of Ocrelizumab IV for the treatment of MS between June 2017 and April 2024.

Patients (66% Female, 92% White) were 55-59 (n=86), 60-64 (n=90), 65-69 (n=61), 70-74 (n=36), 75-79 (n=19), and 80 and above (n=8) years old at last follow up.  On average, participants were treated with Ocrelizumab for 3.2 years. The average MS disease duration was 20 years.  MS phenotype was considered RRMS 44%, SPMS 20%, PPMS 14%, atypical presentation (e.g. tumefactive) 4%, or unknown/unreported (19%).  Ocrelizumab was the third line or higher therapy in 55%, and the average Expanded Disability Status Scale (EDSS) was 4.9.  JCV antibody was seropositive (index > 1.5) in 31% tested, and 22% of participants had hypogammaglobulinemia (IgG < 600 mg/dL) at some point during Ocrelizumab. There were 523 infections in 13,408 person-months of observation, including urinary tract infections (259), COVID-19 (110), upper respiratory tract infections (51), lower respiratory tract infections (21), sepsis (9), and others (73). There were 53 hospitalizations and one death related to infection during Ocrelizumab.

We provide an assessment of a high number of older adults with MS on Ocrelizumab. In this referral center, there were 30.8 non-COVID infections per 1,000 person-months. Our findings can enable future patients and healthcare providers to assess treatment outcomes with B-cell-depleting therapies for MS in expanded age groups.