Abstract
Background & Objectives: Real-world evidence on the effectiveness of ocrelizumab (OCR) as first-line (1L) therapy in people with relapsing multiple sclerosis (pwRMS) is growing. Long-term observational data are essential to understand the impact of OCR over extended treatment periods. This study aimed to assess the impact of OCR 1L treatment on disease activity and worsening in the ongoing MSBase OCR-R (MSOCR-R) sub-study, an ongoing 5-year, prospective cohort within the international MSBase registry.
Methods: This analysis included all patients enrolled in MSOCR-R, aged 18-65 years, who had an EDSS (Expanded Disability Status Scale) score ⩽6.5 and had not previously received a disease-modifying therapy at initiation of OCR. Outcomes included treatment persistence, annualized relapse rate (ARR), 24-week confirmed disability progression (24-wCDP), no evidence of disease activity (NEDA-2) and NEDA-3 for patients with first magnetic resonance imaging scan recorded >8 weeks after OCR initiation and ⩾1scan performed thereafter. Time-to-event analysis was performed to investigate 24-wCDP and NEDA, and their fixed-time estimations were summarized using the Kaplan-Meier method.
Results: As of November 2024, 184 pwRMS treated with OCR as 1L therapy were enrolled in MSOCR-R across 8 countries, primarily from Australia (n=97), Kuwait (n=51), and Turkey (n=11). Baseline characteristics: 66.3% were female; mean (SD) age 37.3 (10.9) years; median time since symptom onset, 1.6 years (interquartile range [IQR] 0.4-5.2); median EDSS score 2.0 (IQR 1.0-3.0). Median time on OCR treatment was 4.0 years (IQR 3.2-5.1) and 85.3% of patients remained on treatment. Overall ARR was 0.03 (95% confidence interval [CI] 0.02-0.05). The majority of patients did not experience disability worsening with 94.0% (95% CI 87.5%-97.2%) remaining free of 24-wCDP at 2 years. NEDA-2 was achieved in 82.6% of patients. NEDA-3 could be assessed in a subset of 93 patients with re-baselined scan and was achieved in 75.3% of patients. The cumulative probabilities of remaining on NEDA-2 and NEDA-3 were 88.0% (95% CI 82.1%-92.0%) and 80.6% (95% CI 71.0%-87.3%) at 2 years, respectively. Results updated with November 2025 cutoff data will be presented, including progression independent of relapses and treatment persistence.
Conclusions: In this updated analysis of the MSOCR-R study, first-line ocrelizumab treatment resulted in highly effective control of relapses and disability progression, and most patients remained on treatment. Early initiation of ocrelizumab may provide long-term clinical benefits to patients with RMS.