High NEDA and No PIRA in Natalizumab-Treated Patients With Pediatric-Onset Multiple Sclerosis.

Background and objectives: Although pediatric-onset multiple sclerosis (POMS) is characterized by a more rapid accumulation of CNS inflammation than adult-onset MS (AOMS), the therapeutic algorithms applied in POMS are usually based on AOMS therapeutic outcomes. To define a high-efficacy treatment (HET)-based strategy to treat POMS, we designed an observational retrospective study aimed at evaluating the efficacy and safety of natalizumab (NTZ) in naïve POMS and AOMS.

Methods: Starting from 160 patients, we applied a 2:1 (adult:pediatric) matching on propensity scores and obtained 32 patients with NTZ-treated POMS and 64 with AOMS, estimated from a multivariable logistic regression model. All patients were clinically and radiologically followed up every 6 months for a mean period of 46.0 ± 26.9 months.

Results: Following re-baseline at month 6, no difference (log-rank test: p = 0.924) in new and enlarging T2 white matter lesions, postcontrast T1 lesions, and relapse rate were observed between POMS and AOMS throughout the study. Progression independent of relapse activity (PIRA) was never observed in POMS, while 9 of 64 patients with AOMS (12.5%) had PIRA events during the follow-up (40.0 ± 25.9 months; log-rank p value 0.0156). JCV seroconversion rate during NTZ infusion did not differ between POMS and AOMS (log-rank test p = 0.3231). Finally, no serious adverse event was observed in both POMS and AOMS.

Discussion: The favorable outcomes observed on clinical, especially in PIRA, and radiologic parameters strongly support the use of NTZ as a first-choice HET in POMS.