Retinal atrophy in multiple sclerosis is similar with extended versus standard interval natalizumab therapy.

BACKGROUND: Retinal ganglion cell + inner plexiform layer (GCIPL) atrophy reflects global neurodegeneration and disability in multiple sclerosis. Extended interval dosing (EID; every 5-8 weeks) natalizumab reduces progressive multifocal leukoencephalopathy risk in people with relapsing-remitting multiple sclerosis (PwRRMS) versus standard interval dosing (SID; every 4 weeks). OBJECTIVES: To assess if EID versus SID natalizumab differentially impacts GCIPL atrophy, other retinal layer (peripapillary retinal nerve fiber layer (pRNFL), inner nuclear layer (INL), and outer nuclear layer (ONL)) atrophy, and/or clinical outcomes in PwRRMS. METHODS: PwRRMS underwent longitudinal Cirrus high-definition optical coherence tomography (OCT), expanded disability status scale (EDSS), 100% and 2.5% contrast letter-acuity (LA) assessments. Analyses utilized mixed-effects regression models adjusting for age, sex, race, disease duration, optic neuritis history, and interval between treatment initiation and OCT monitoring, accounting for within-subject, inter-eye correlations. RESULTS: GCIPL and pRNFL atrophy rates were not significantly different between EID (n = 22) and SID (n = 109) natalizumab (p = 0.48, p = 0.24). INL and ONL atrophy were faster with EID versus SID natalizumab (p = 0.02, p < 0.001). Age was higher (44.8 vs. 40.1 years, p = 0.03) and disease duration longer (15.2 vs. 8.4 years, p < 0.001) in the EID natalizumab cohort. Annual EDSS and 100% and 2.5% LA changes were similar between cohorts. CONCLUSION: We detected no significant difference in GCIPL or pRNFL atrophy, or clinical outcomes, between EID and SID natalizumab. Faster INL and ONL atrophy may relate to cohort demographic differences.