The effect of alemtuzumab on neurodegeneration in relapsing-remitting multiple sclerosis: A five-year prospective mono-center study.

ABSTRACT

BACKGROUND: Relapsing-remitting multiple sclerosis (RRMS) is an inflammatory and neurodegenerative disease. After two or more short courses of alemtuzumab (ALZ), an immune reconstitution is achieved, which long-term results in reduced disease activity. We aimed to investigate the effect of ALZ on measures of neurodegeneration (i.e., brain atrophy, and retinal layer thinning). METHODS: We designed an observational prospective mono-center study in RRMS patients initiating ALZ treatment. Patients were assessed at baseline (month 0) and thereafter annually for five years with clinical measures, synthetic magnetic resonance imaging (SyMRI) and optical coherence tomography (OCT), with a re-baseline SyMRI scan and an OCT exam 24 months after initiating ALZ. Persons with neurological symptoms but without evidence of neurological disease served as symptomatic controls (SCs, n = 27). RESULTS: Forty-nine RRMS patients were included. Baseline median expanded disability status scale [2.0 (IQR 1.5)] was unchanged during follow-up, 71 % were progression-free, 33 % achieved no evidence of disease activity-3 (NEDA-3). Between baseline and month 60, SyMRI showed a reduction of brain parenchymal fraction (BPF) and grey matter (GM) volume in patients. The BPF reduction was greater in RRMS patients than in SCs (p < 0.05), and more pronounced in patients with high pre-baseline disease activity than in those without (p < 0.01). OCT showed significant thinning of macular ganglion cell and inner plexiform layers (mGCIPL) and in peripapillary retinal nerve fiber layer (pRNFL) in patients. In contrast, absolute values of white matter (WM) volume and myelin content (MyC) quantified by SyMRI, were stable or increased after re-baseline (month 24) and up to month 60, and this increase appeared limited to patients without high pre-baseline disease activity and to patients with NEDA-3 or disability worsening during follow-up. A strong positive correlation between WM volume and GM volume at baseline was lost after ALZ intervention for their delta values, i.e., change from re-baseline (month 24) to month 60. While the positive baseline correlation between WM volume and MyC increased for their delta values, the positive baseline correlation between GM volume and MyC changed to negative for their delta values. CONCLUSION: We showed that neurodegeneration continued in RRMS patients under ALZ treatment, but it appeared to be limited to BPF and GM, and more pronounced in patients with disease activity. Our data suggest that patients who respond to ALZ treatment show signs of remyelination. OCT and SyMRI have potential to quantify measures of neurodegeneration that is affected by treatment intervention in RRMS.