Effect of different initial rituximab regimens on B cell depletion in children with autoimmune neurological diseases.

Background: Rituximab (RTX) is a promising B-cell-depleting monoclonal antibody used to treat several autoimmune neurological diseases in children. The RTX administration regimen relies on the reconstitution of B cells in the peripheral blood.

Objective: The objective of this study was to investigate the effect of different initial RTX regimens on B cell depletion.

Methods: This single-center retrospective analysis included children with autoimmune neurological diseases who received RTX; Group 1 received two infusions of 375 mg/m RTX, while Group 2 received four infusions of the same dose. We examined the evolution of B cells at regular intervals in patients. The time required for B cell reconstitution, risk factors, and the effect on immunoglobulin (Ig) and T cells were studied.

Results: A total of 113 patients with the first course of rituximab were included. Median time required for B cell reconstitution was 147.7 [130.1-165.2] and 181.9 [165.2-198.6] days in Group 1 and 2 respectively (p = 0.008). Ig production was affected by RTX, which reduced IgG, IgA and IgM serum concentrations, yet within the normal level. There was significant difference in the decline of IgG between the two groups. Absolute cell counts for T cells did not change over time after treatment, and the variation trend was similar in the two groups.

Conclusion: The initial regimen of RTX impacts time required for B cell reconstitution. There was an increased time to B cell reconstitution with four standard infusions of RTX when compared with two standard infusions. Furthermore, as the prolonged B cell depletion leads to decreased antibody production, regular measurements of serum Ig concentrations after RTX treatment and follow-up should be performed regularly.