Clinical and radiological activity after extended interval and standard interval dosing of ocrelizumab in multiple sclerosis: A systematic review and meta-analysis

Background Ocrelizumab is an anti-CD20 monoclonal antibody that is highly effective in reducing MS clinical and radiological activity. The standard dosing regimen consists of infusing 600 mg of ocrelizumab every six months. However, concerns about increasing risks of infection and lowered vaccine response, particularly during the COVID-19 pandemic, prompted clinicians to extend the dosing interval between ocrelizumab infusions for some patients. Several observational studies have compared the effects of extended-interval dosing (EID) and standardinterval dosing (SID) of ocrelizumab on MS relapse rate and MRI activity. Method We performed a systematic review and meta-analysis of the current literature to summarize studies comparing ocrelizumab EID and SID on MS disease activity in patients with MS. Two independent reviewers searched PubMed, Scopus, EMBASE, Web of Science, and Google Scholar on the 1st of June 2024. Results Our systematic search revealed 348 records, and after deleting duplicates, 29 records remained. Twenty-eight full texts were evaluated; ultimately, 16 studies remained for systematic review. In this meta-analysis, extended interval dosing (EID) was defined variably across studies, with some considering even a one-month delay as EID. The pooled odds ratios (ORs) for clinical and MRI activity, comparing ocrelizumab EID to SID groups, were estimated as 1.04 (95%CI: 0.67-1.6, I2=30%, P=0.21) and 1.31(95%CI: 0.90-1.92) (I2=15%, P=0.32), respectively. Conclusion This systematic review and meta-analysis suggest that ocrelizumab EID is not associated with greater odds of clinical and radiological disease activity in patients with MS.