Abstract Details

Title Comparative Effectiveness of Standard vs Extended Rituximab Dosing Intervals in Relapsing Remitting Multiple Sclerosis

Topic Multiple Sclerosis

Presentation(s) S31 - Multiple Sclerosis: Therapeutics and Clinical Decision Making (2:36 PM-2:48 PM)

Poster/Presentation
Number 009

Background Extending rituximab dosing intervals beyond every 6 months lowers the risk of infections but effectiveness is unknown.

Objective To determine whether extending rituximab dosing intervals to ≥12 months results in higher disease activity compared to standard intervals in persons with relapsing remitting multiple sclerosis (pwRRMS)

Design/Methods We conducted a retrospective cohort study of pwRRMS treated with ≥1 dose of rituximab from the membership of Kaiser Permanente Southern California, 2008-2022. The complete electronic health record was reviewed to obtain clinical and demographic variables.

Results We identified 2124 rituximab-treated pwRRMS with a median follow-up of 3.8 years (IQR 2.1-5.4). The median age at rituximab initiation was 37.0 years and 73.2% patients identified as female, 14.9% as Black, 38.4% as Hispanic. Rituximab dosing interval was extended at least once in 1579 (74.3%) patients (median extended interval 11.6 months, range 4.3-112.2, mean number of extended intervals=3, IQR 2-4). The majority of patients were relapse- and MRI disease activity-free on standard interval dosing (<q8 months) and extended (≥q8mo) interval dosing (95.05% and 95.12%, respectively). The crude incidence rate of relapse and/or asymptomatic MRI disease activity per 100-person-years (95%CI) stratified by dosing interval (in months) was as follows: <8, 2.9 (2.3-3.5); ≥8 to <11, 1.9 (1.0-2.7); ≥11 to <15, 1.0 (0.6-1.4); ≥15 to <20, 1.8 (0.8-2.8); ≥20 to <26, 1.6 (0.4-2.8) and ≥26, 2.2 (1.4-3.1). Patients with relapses and/or asymptomatic MRI disease activity were more likely to be younger, have longer disease duration and prior MS treatment exposure at rituximab initiation compared with disease activity-free patients.

Conclusions The vast majority of rituximab-treated RRMS patients remained inflammatory disease-activity free (>95%) on standard and extended dosing intervals in this large, diverse population-based cohort. Taken together with previous studies, these findings suggest that treating RRMS patients with B-cell depleting agents q6 months increases the risk of adverse events without improving effectiveness.

Authors/Disclosures
Annette M. Langer-Gould, MD, PhD (Kaiser Permanente Southern California) PRESENTER	An immediate family member of Dr. Langer-Gould has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Annals of American Thoracic Society. The institution of Dr. Langer-Gould has received research support from PCORI. The institution of an immediate family member of Dr. Langer-Gould has received research support from PCORI, ARQ, NIH. Dr. Langer-Gould has a non-compensated relationship as a Voting Member with ICER CTAF Panel that is relevant to AAN interests or activities.
Jessica B. Smith, MPH (Kaiser Permanente)	Ms. Smith has nothing to disclose.
Fernando Torres	No disclosure on file
Bonnie Li	No disclosure on file