Different lymphocyte counts of multiple sclerosis patients treated with ofatumumab and ocrelizumab: A retrospective observational study

Abstract

Introduction: Patients with Multiple Sclerosis (pwMS) treated with anti-CD20 (cluster of differentiation) monoclonal antibodies (mAbs) such as ocrelizumab (OCR) and ofatumumab (OFA) show a reduction mainly of B-lymphocytes, but also other lymphocyte subsets can be affected by these treatments. There is limited data on differences between lymphocyte subset counts of pwMS after treatment initiation with OCR or OFA. Objective: To compare lymphocyte subset counts after treatment initiation in pwMS treated with OCR and OFA. Methods: We analyzed 22 pwMS initiated on OFA and 56 sex-, age- and MS course matched pwMS initiated on OCR from 2 prospectively collected observational MS databases (Bern [n: OFA 14, OCR 44] and Vienna [n: OFA 8, OCR 12]) statistically comparing lymphocyte subset counts (Mann Whitney Test). Results: We found that pwMS treated with OCR showed a stronger reduction of CD20 B-lymphocytes (P =.001), and a trend towards lower counts of CD8+ T cells (P =.056) compared to pwMS treated with OFA, whereas reduction of total lymphocyte, CD4+ lymphocyte and NK cell count was equally distributed between both treatments. Conclusion: Different effects on lymphocyte subpopulations appear to be present in pwMS after treatment initiation with different anti-CD20 mAbs. Further studies are needed to determine potential effects on anti-CD20 treatment efficacy as well as treatment associated risks such as failed vaccinations and infections.