Treatment outcomes in multiple sclerosis using reduced and extended interval ocrelizumab dosing

People with multiple sclerosis (pwMS) treated with ocrelizumab at our tertiary hospital during the COVID-19 pandemic were exposed to reduced dosing of 300 mg (RD) every 6 months, and also extended interval dosing (EID), due to concerns around infection risk and challenges attending hospital. We analysed clinical, MRI and laboratory outcomes to assess treatment effectiveness and safety compared with standard dosing (SD).

We collected data retrospectively on all people treated with ocrelizumab through our MS clinic from 01/01/2018 to 01/01/2024. Dates and dosage of ocrelizumab; expanded disability status score; clinical relapse; MRI brain and spine lesions; circulating B cells and immunoglobulin levels were collated. Annualised relapse risk and other parameters were calculated over time.

A total of 113 pwMS were eligible for inclusion in the analysis. 76 pwMS received RD ocrelizumab, and 21 had EID. We found no significant difference in the clinical or radiological outcomes between the SD, RD or EID treatment regimens. During the follow-up period one person had a relapse just prior to EID at 9 months, and one had a relapse while on SD. B-cell repopulation prior to the subsequent dose occurred more frequently during EID compared with SD. There was a non-significant trend to higher immunoglobulin levels with RD and EID regimens compared with SD.

Reduced exposure to ocrelizumab in pwMS, through RD or EID, did not result in significant differences in clinical or radiological outcomes in our population. This real-world single centre study supports further prospective exploration of these strategies.