Extended Interval Dosing of Ocrelizumab in Patients with Multiple Sclerosis Is Not Associated with Meaningful Differences in Disease Activity (P14-3.010)

Abstract

<h3>Objective:</h3> To determine if extended interval dosing (EID) of ocrelizumab is associated with changes in disease activity in patients with multiple sclerosis (MS). <h3>Background:</h3> During the COVID-19 pandemic, EID of ocrelizumab (standard interval dosing (SID)= every 6 months) was employed variably by neurologists at our center due to concerns about COVID-19 risk or reduced COVID-19 vaccine efficacy. This time period provides the opportunity to evaluate whether EID is associated with greater risk of breakthrough MS activity. <h3>Design/Methods:</h3> Medical records of patients at our institution who were on ocrelizumab treatment as of March 2020 were reviewed. Demographic, clinical, and imaging data and infusion dates were collected. EID was defined as ≥ 8 months in the primary analysis and ≥ 12 months in secondary analyses. <h3>Results:</h3> Overall, 364 patients, 275 (75.5%) with relapsing-remitting MS (RRMS) and 89 (24.5%) with progressive MS (PMS), were included (mean age 42.4±10.9 years; 72% females). They received ocrelizumab for an average of 38.2±14.9 months; and infusion intervals ranged from 4 to 32 months. 190 patients (52.4% of RRMS and 51.6% of PMS) had at least one EID ≥ 8 months, while 89 patients (21% of RRMS and 18% of PMS) had at least one EID ≥ 12 months. There was no difference in sex, age, or MS type between EID and SID groups. Reasons for EID (≥ 8 months) included COVID concerns (58%), infections (8%), pregnancy (8%), or other (26%). Only 1 EID and 1 SID patient had a clinical relapse. Among 258 RRMS patients who had re-baseline MRI after starting ocrelizumab, 3 (2.2%) EID patients (≥ 8 months) had new lesions on imaging vs none in those with SID. No participant with PMS had breakthrough MRI activity. <h3>Conclusions:</h3> Results suggest no marked risk of inflammatory MS activity associated with EID for ocrelizumab when compared to SID. <b>Disclosure:</b> Dr. Bou Rjeily has nothing to disclose. The institution of Dr. Fitzgerald has received research support from NIH. The institution of Dr. Fitzgerald has received research support from National MS Society. Dr. Mowry has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for UpToDate. The institution of Dr. Mowry has received research support from Biogen. The institution of Dr. Mowry has received research support from Teva. The institution of Dr. Mowry has received research support from Genzyme. The institution of Dr. Mowry has received research support from Genentech.