Real-World 24-Month Outcomes of Ofatumumab in Relapsing Multiple Sclerosis: Efficacy, Safety, and the Impact of Frailty

Introduction: Ofatumumab (OFA) is a highly effective therapeutic option for multiple sclerosis (MS), but real-world data on its efficacy and safety remain limited. We evaluated the real-world efficacy and safety of OFA in patients with MS and explored the predictive value of frailty. Methods: We retrospectively collected clinical and MRI data from 12 MS centers in Central Italy, including patients who initiated OFA between April 2022 and January 2024. We assessed annualized relapse rate (ARR), clinical relapses, radiological activity, and safety. Frailty, defined as increased vulnerability due to age-related health deficits, was measured using a frailty index (FI). The study was approved by the local Ethics Committee (No. 6357). Results: A total of 242 patients with MS were included (66.8% female and 33.2% male; mean age: 38.9 ± 10.3 years; disease duration: 7.7 ± 7.6 years). Of these, 95 (39.2%) were treatment-naïve, and 147 (60.8%) had switched from another therapy, mostly a first switch. The mean follow-up was 15.4 ± 5.4 months; all patients completed 12-month follow-up, and 103 completed 24 months. ARR dropped from 0.9 to 0.02 (p < 0.001). Only 4 patients (1.6%) had a clinical relapse, all within 6 months (mean time: 3.0 ± 1.8 months). Expanded Disability Status Scale (EDSS) scores remained stable (p > 0.05). MRI activity occurred in 10 patients (4.1%) at 6 months and 3 (1.2%) at 12 months; none at 24 months. Adverse events included flu-like symptoms (34.3%), injection site reactions (8.2%), and infections (18.5%). Among 239 patients assessed for frailty (mean FI: 0.06 ± 0.08), 187 were relatively fit (FI ≤ 0.10), 30 least fit, and 22 frail. FI predicted 24-month confirmed disability progression (p = 0.0068), with significant variation by frailty level (p = 0.0009). Conclusion: This real-world study suggests that OFA is effective and safe for MS, offering rapid disease control. Lower frailty levels suggest preferential use in patients with lower baseline disability. Further large-scale, long-term studies are needed.