Influence of Previous Disease-Modifying Drug Exposure on T-Lymphocyte Dynamic in Patients With Multiple Sclerosis Treated With Ocrelizumab

Background and Objectives\r\nTo investigate the longitudinal dynamic of lymphocyte subsets during treatment with ocrelizumab\r\n(OCR) in patients with multiple sclerosis (PwMS).\r\nMethods\r\nA multicenter retrospective study was conducted in 161 PwMS starting treatment with OCR\r\ngrouped in naive (naive, n = 40), switching from fingolimod (FTY, n = 52), and switching from\r\nother immunomodulating drugs (other, n = 69). Mean lymphocyte subset (total, CD3+, CD4+,\r\nCD8+, CD20+, and natural killer) counts were analyzed at baseline, 6 months, and 12 months.\r\nRate of lymphocytopenia for each subset was calculated at all time points in all groups.\r\nResults\r\nMean total, CD3+, and CD4+ counts were significantly different among groups (p < 0.001) at all\r\ntime points, whereas CD8+ and CD20+ counts only at baseline (p = 0.0157; p < 0.001),\r\nconsistently lower in FTY. After adjustment for baseline values, interaction time*group was not\r\nstatistically significant (p > 0.05 for each subset). The odds of lymphopenia were significantly\r\nhigher among FTY patients compared with naive for total, CD3+, CD4+, and CD20+ cells at\r\nbaseline, for total and CD4+ cells at the sixth month, and for total cells at the 12th month.\r\nDiscussion\r\nOCR per se exerts a modest depleting effect on T cells that seems rather due to a carryover\r\nphenomenon of previous therapies, particularly FTY. These data may help in the overall\r\nevaluation of the risk/benefit profile of treatment sequencing.