Efficacy and safety of ofatumumab in Chinese participants with multiple sclerosis: results from a 12-month, prospective, open-label, multicenter study

Abstract Background Ofatumumab, a fully human anti-CD20 monoclonal antibody, has shown superior efficacy and a comparable overall safety profile to teriflunomide in the pivotal ASCLEPIOS I/II trials in people living with relapsing multiple sclerosis (plwRMS). However, data on the efficacy and safety of ofatumumab, a high-efficacy therapy, in Chinese plwRMS are limited. Methods This 12‑month prospective, open‑label, multicenter study evaluated the efficacy and safety of ofatumumab in adult Chinese plwRMS aged 18 to 55 years, with an Expanded Disability Status Scale score of 0 to 5.5 and neurological stability prior to baseline. Participants received ofatumumab 20 mg subcutaneously at baseline/Week 0, Week 1, and Week 2, followed by monthly dosing from Week 4 through Month 12. The primary endpoint was annualized relapse rate (ARR). Secondary endpoints included number of gadolinium-enhancing (Gd+) T1 lesions per scan, annualized rate of new or enlarging T2 (neT2) lesions per year, change from baseline in T2 lesion volume, and 3‑month confirmed disability progression (3mCDP). Safety outcomes were also assessed. Results The full analysis set included 99 participants. Five confirmed relapses were reported across all participants with an adjusted ARR of 0.05 (95% confidence interval [CI]: 0.02–0.13). The adjusted number of Gd+ T1 lesions per scan was 0.04 (95% CI: 0.02–0.10) over 12 months. A complete suppression of Gd+ T1 lesions was observed with ofatumumab at Month 12 (100%; 96/96). The annualized rate of neT2 lesions was 0.21 at Month 12 relative to Month 3. A single participant experienced 3mCDP during the study. Overall, 69.7% ( n = 69) of participants experienced at least one treatment-emergent adverse event (AE). AEs were mainly mild to moderate (Grade 1–2 by Common Terminology Criteria for AEs) in severity, with three Grade 3 events reported. The most common AEs were systemic injection‑related reactions (43.4%), COVID‑19 (12.1%), and upper respiratory tract infection (11.1%). No serious AEs or deaths were reported. Conclusion These findings suggest a favorable benefit–risk profile for ofatumumab in Chinese plwRMS. Trial registration The trial is registered with Clinicaltrials.gov registry (NCT05199571; January 6, 2022).