Ocrelizumab extended-interval dosing in multiple sclerosis during SARS-CoV-2 pandemic: a real-world experience

During the COVID-19 pandemic, ocrelizumab administration was frequently postponed because of a lack of safety information and to favour vaccination. The clinical implications of ocrelizumab administration delay in multiple sclerosis (MS) patients were assessed.

Relapsing (RMS) and primary progressive (PPMS) MS patients receiving ocrelizumab for at least 6 months at our centre were retrospectively classified, according to the possible occurrence of a delay (≥4 weeks) in treatment administration. Patients were categorized in the extended-interval dosing (EID) group in the presence of at least one delayed infusion; otherwise they were considered as part of the standard interval dosing (SID) cohort. MS history, magnetic resonance imaging examinations and B-cell counts were also retrospectively collected and analysed.

A total of 213 RMS and 61 PPMS patients were enrolled; 115 RMS and 29 PPMS patients had been treated according to the SID regimen, whilst 98 RMS and 32 PPMS patients were included in the EID cohort. Average follow-up after delay was 1.28 ± 0.7 years in the EID cohort. In RMS, comparing SID and EID patients, no differences were found considering the occurrence of clinical relapses (9.6% vs. 16.3%, p = 0.338), magnetic resonance imaging activity (9.8% vs. 14.1%, p = 0.374) or disability progression (11.3% vs. 18.4%, p = 0.103). Similar findings were observed in PPMS patients. In the pooled EID group, treatment delay correlated with CD19-positive relative (r = 0.530, p < 0.001) and absolute (r = 0.491, p < 0.001) cell counts, without implications on disease activity.

Sporadic ocrelizumab administration delay granted sustained treatment efficacy in our cohort. Prospective data should be obtained to confirm these observations and set up systematic extended-interval regimens.