Effect of Ocrelizumab in Blood Leukocytes of Patients With Primary Progressive MS

OBJECTIVE: To analyze the changes induced by ocrelizumab in blood immune cells of patients with primary progressive MS (PPMS). METHODS: In this multicenter prospective study including 53 patients with PPMS who initiated ocrelizumab treatment, we determined effector, memory, and regulatory cells by flow cytometry at baseline and after 6 months of therapy. Wilcoxon matched paired tests were used to assess differences between baseline and 6 months' results. p Values were corrected using the Bonferroni test. RESULTS: Ocrelizumab reduced the numbers of naive and memory B cells (p < 0.0001) and those of B cells producing interleukin (IL)-6, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-alpha (TNFα) (p < 0.0001 in all cases). By contrast, the proportions of plasmablasts and B cells producing GM-CSF and TNFα increased significantly, suggesting the need for treatment continuation. We also observed a decrease in CD20(+) T-cell numbers (p < 0.0001) and percentages (p < 0.0001), and a clear remodeling of the T-cell compartment characterized by relative increases of the naive/effector ratios in CD4(+) (p = 0.002) and CD8(+) (p = 0.002) T cells and relative decreases of CD4(+) (p = 0.03) and CD8(+) (p = 0.004) T cells producing interferon-gamma. Total monocyte numbers increased (p = 0.002), but no changes were observed in those producing inflammatory cytokines. The immunologic variations were associated with a reduction of serum neurofilament light chain (sNfL) levels (p = 0.008). The reduction was observed in patients with Gd-enhanced lesions at baseline and in Gd− patients with baseline sNfL >10 pg/mL. CONCLUSIONS: In PPMS, effector B-cell depletion changed T-cell response toward a low inflammatory profile, resulting in decreased sNfL levels.