It is increasingly understood that grey matter (GM) atrophy is associated with disability progression and cognitive decline in patients with multiple sclerosis (MS). Previously, we demonstrated that treatment with cladribine tablets 3.5 mg/kg bodyweight (CT3.5; cumulative dose over 2 years) in the CLARITY study (NCT00213135) decreased brain atrophy compared with placebo, which was closely associated with a lower risk of disability progression [De Stefano et al. MSJ 2018].
Post hoc evaluation of GM and white matter (WM) volume changes in patients with relapsing MS randomized to CT3.5 or placebo in the CLARITY study.
Images from pre-gadolinium T1-weighted magnetic resonance imaging scans of patients randomized to CT3.5 or placebo for 2 years in CLARITY were evaluated using SIENA-XL software. Images from 0–6 months (CT3.5, n=267; placebo, n=265) were analyzed independently of images from 6–24 months (CT3.5, n=184; placebo, n=186) to account for the potential effects of pseudoatrophy. Annualized mean changes in percentage of GM volume (PGMV) or WM volume (PWMV) between CT3.5 and placebo for 0–6 and 6–24 months were compared using a variance model.
CT3.5 reduced GM and WM volume vs placebo in the first 6 months, consistent with pseudoatrophy [PGMV change: CT3.5 -0.53 vs placebo -0.25 (p=0.045); PWMV change: CT3.5 -0.49 vs placebo -0.34 (p=0.137)]. Brain volume loss from 6–24 months was reduced in patients randomized to CT3.5 with the difference between CT3.5 and placebo significant for GM [PGMV change: CT3.5 -0.90 vs placebo -1.27 (p=0.026); PWMV change: CT3.5-0.32 vs placebo -0.40 (p=0.52)].
Volume loss reduction in WM and, particularly, in GM was noted from 6-24 months in CT3.5-treated patients vs placebo, after a period of pseudoatrophy (0-6 months). Such findings suggest that CT3.5 significantly reduces brain atrophy predominantly in the GM, an effect that may contribute to lower risk of disability progression.