Ocrelizumab Extended Interval Dosing in Primary Progressive Multiple Sclerosis: An Italian Experience

Background: The intervals between two courses of anti CD20 therapies in the COVID19 pandemic era provided the opportunity to individually delay therapy, known as extended interval dosing (EID).Methods: We collect real-world data on patients with primary progressive MS (PPMS) treated with Ocrelizumab (OCR) during the COVID'19 pandemic. The observation period in which the standard interval dosing (SID) or EID occurred (always a maintenance cycle, 600 mg) was from January 2020 to June 2021. All patients had two infusions during the observation period. Our first aim was to compare confirmed disability progression (CDP) between SID and EID patients.Results: From a total cohort of 410 patients treated with OCR, 96 patients fulfilled the inclusion criteria. All patients received two infusions during the index window, 71 received only SID infusions whilst 25 received at least one EID infusion throughout the entire follow-up. During the entire available follow-up (median 10 months, IQR 7-11), CDP was recorded in 5 patients (3/71, 4.2% SID and 2/25, 8% EID, V-Cramer = 0.141, p-value = 0.167). EID regimen did not influence the risk of CDP during the investigated follow up.Conclusion: In our multicentre real-world cohort, the EID regimen in PPMS patients did not result in increased CDP during the available follow-up.