Real-world effectiveness of ocrelizumab in relapsing multiple sclerosis: An MSBase registry sub-study

Introduction: The MSOCR-R study evaluates the long-term effectiveness of ocrelizumab (OCR) in patients with relapsing multiple sclerosis (RMS) in real-world clinical settings. Methods: MSOCR-R is an ongoing, prospective, longitudinal, observational cohort study of people with RMS newly treated with OCR, using data from the international MSBase registry. The study started in July 2018, and data collected up to October 2023 were analyzed. Outcomes were confirmed disability worsening (CDW), progression independent of relapses (PIRA), and no evidence of disease activity (NEDA-3: absence of relapse, 24-week CDW, or imaging activity). Results: Overall, 1011 patients were enrolled (18.1% initiated OCR first-line therapy; 81.9% switched from previous treatment), with a median time of 3.4 years on OCR treatment. About 67% of patients were females. At OCR initiation, mean age was 41.9 years, median disease duration was 10.4 years, and median Expanded Disability Status Scale score was 3.0. The 4-year Kaplan–Meier probabilities of 24-week CDW or PIRA were 25.2% (95% CI 21.6–29.1) and 21.9% (95% CI 18.3–25.2), respectively. Annualized relapse rate substantially decreased from 0.58 (95% CI 0.53–0.63) before OCR to 0.05 (95% CI 0.04–0.06) after treatment initiation. NEDA-3 was assessed in 366 patients and the probability of achieving NEDA-3 was 39.7% (95% CI 36.0–43.5) at 4 years. Persistence on OCR was 88.0% (95% CI, 85.2–90.3) at 4 years. Better clinical outcomes were consistently observed among the first-line treatment cohort. Conclusion: The MSOCR-R study provides strong real-world evidence of OCR effectiveness in people with RMS.