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

Background and purpose: 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. Methods: 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. Results: 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. Conclusions: 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.