6ER-030 Experience with natalizumab in the treatment of multiple sclerosis

<h3>Background and Importance</h3> One of the main limitations of treating multiple sclerosis (MS) with natalizumab is the risk of developing progressive multifocal leukoencephalopathy (PML). <h3>Aim and Objectives</h3> This study aims to assess the effectiveness and safety of natalizumab in the treatment of relapsing-remitting MS. <h3>Material and Methods</h3> Single-centre, observational-retrospective study (October 2007 to March 2024), including all MS patients treated with natalizumab. The patients’ characteristics and necessary clinical data were obtained from the patients‘ medical records. Disease progression was evaluated using the Expanded Disability Status Scale (EDSS) and radiological activity through MRI, identifying new T2 lesions or gadolinium-enhancing (Gd+) lesions. <h3>Results</h3> A total of 43 patients were included (mean age 41.9 years (24–62); 74.4% female). The mean baseline EDSS was 2.3, remaining stable after the first year of treatment (n=37), increasing to 2.6 in the second year (n=33), and reaching 3.4 after 10 years (n=9). In the first 2 years, 32.5% (n=14) of patients developed at least one new T2 lesion, and 16.3% (n=7) developed at least one new Gd+ lesion. After 10 years, these rates rose to 48.9% (n=21) and 25.6% (n=11), respectively. The mean treatment duration was 65.6 months (2–173). The main reasons for treatment discontinuation (n=22) were high-risk of PML (68,2%, n=15) and radiological progression (22,7%, n=5). Regarding safety, 44.2% of patients (n=19) experienced treatment-related adverse events, mainly infections (36.8%, n=7). No cases of PML were reported. <h3>Conclusion and Relevance</h3> Natalizumab remains a viable option for the treatment of relapsing-remitting MS, demonstrating both short and long-term effectiveness, high persistence, and a favourable safety profile. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest