Brain volume loss is present in Japanese multiple sclerosis patients with no evidence of disease activity.

No evidence of disease activity-3 (NEDA-3), defined as absence of clinical relapse, disability progression, and brain magnetic resonance imaging (MRI) activity, has emerged as the therapeutic target of disease-modifying therapy for multiple sclerosis (MS). However, recent studies have revealed that NEDA-3 might not be sufficient to prevent cognitive deterioration and predict long-term disability. In addition to NEDA-3, brain atrophy has recently been recognized as a pivotal biomarker that is closely associated to disability in patients with MS. This retrospective observational study included 22 Japanese MS patients with relatively mild disease (median expanded disability status scale = 1.75). Fifteen patients (68%) received disease-modifying therapy (DMT), including interferon (IFN)-β (n = 6), IFN-β, or azathioprine followed by fingolimod (n = 4), fingolimod (n = 4), and IFN-β followed by natalizumab (n = 1). It revealed that 14 (64.6%) patients achieved NEDA-3 in the 2-year observational period. However, nine (64.3%) of the patients with NEDA-3 were revealed to have a significant BVL, defined as ≥ 0.4% per year. Importantly, these nine patients included all patients receiving IFN-β therapy (n = 6), whereas patients without BVL included none of these patients. Conversely, patients treated with fingolimod following IFN-β did not have significant BVL. These results indicate that evaluation of NEDA-4 is encouraged especially in patients with IFN-β therapy in MS clinical practice in Japan although Japanese MS patients have generally been thought to possess a milder disease including brain atrophy compared to their Western counterparts.