Therapeutic options and outcomes in pediatric-onset multiple sclerosis with a focus on fingolimod—Eastern European tertiary center experience and literature review

Pediatric-onset multiple sclerosis (POMS) is a rare but increasingly recognized autoimmune condition affecting children under 18 years. The disease course is more aggressive than in adults, with frequent relapses, rapid accumulation of lesions, and early onset of motor and cognitive impairments. Due to limited approved disease-modifying therapies (DMTs) for children, first-line treatment often relies on injectable agents with moderate efficacy. Fingolimod, a high-efficacy therapy (HET), was recently approved for pediatric use, yet its uptake remains variable across regions. This retrospective, observational, monocentric study included 115 children diagnosed with POMS between 2018 and 2024 in a tertiary center in Romania. Patients were divided into three groups: 79 treated with interferon beta (IFNβ), 14 treated with fingolimod (FTY), and 22 untreated. We compared clinical outcomes, including annualized relapse rate (ARR), Expanded Disability Status Scale (EDSS) scores, and brain MRI lesion burden over 1 to 3 years of follow-up. Adverse events and treatment delays were also analyzed. All fingolimod-treated patients remained relapse-free during follow-up, while 42% of those on IFNβ experienced between 1 and 8 relapses. Fingolimod patients had significantly fewer new MRI lesions after 2 and 3 years of treatment (p < 0.01). EDSS scores remained stable or improved in both treated groups, with better outcomes in the FTY group. Adverse events included flu-like symptoms in all IFNβ-treated children and lymphopenia (mild to severe) in all FTY cases, managed by dose adjustment. Treatment initiation was delayed in the FTY group due to vaccination status and age-related barriers. Fingolimod demonstrated superior efficacy and comparable safety to IFNβ in pediatric MS. Our findings support early initiation of HETs in POMS and highlight real-world barriers to their implementation in Eastern Europe, including vaccination requirements and caregiver hesitancy.