Autologous haematopoietic stem cell transplantation affects paramagnetic rim lesions in multiple sclerosis

Background: Available literature shows a marginal or no effect of disease-modifying therapies on paramagnetic rim lesions (PRLs), a promising magnetic resonance imaging marker of chronic inflammation in multiple sclerosis. Objective: To investigate longitudinal changes in PRL count in people with multiple sclerosis treated with autologous haematopoietic stem cell transplantation (AHSCT), exploring their potential as predictors of treatment response. Methods: Monocentric study including 30 AHSCT–treated people with multiple sclerosis who performed at least two brain magnetic resonance imaging scans with susceptibility-weighted imaging either (i) before and after AHSCT (pre/post-AHSCT group; n = 12) or (ii) after AHSCT only (post-AHSCT group; n = 18). Results: In the pre/post-AHSCT group, PRL count decreased in 2/5 (40%) PRL–positive cases over a median of 21 (7–74) months; 5/26 (19%) PRL s resolved. In the post-AHSCT group, PRL count decreased in 4/7 (57%) PRL –positive cases over a median of 51 (6–57) months; 10/20 (50%) PRL s resolved. The annualised paramagnetic rim lesion disappearance rate was −0.36 and −0.43 in the two groups, respectively. No new PRL appeared. Baseline PRL count correlated with disability in the pre/post-AHSCT group only (r = 0.741, p = 0.006). Conclusions: Given the reported long persistence of PRLs, these data indicate that AHSCT may accelerate their disappearance, suggesting an effect within the central nervous system on microglia/macrophages. PRLs could predict response to central nervous system-bioavailable treatments.