Switching from ocrelizumab to ofatumumab: key potential reasons based on real-world clinical practice

In everyday neurological practice, B-cell-depleting therapies are playing an increasingly important role in the treatment of active forms of multiple sclerosis (MS). Among the most well-studied agents are monoclonal antibodies (mAbs) targeting the CD20 receptor on lymphocytes: ocrelizumab (a humanized mAb) and ofatumumab (a fully human mAb), which bind to different extracellular epitopes of the CD20 receptor. In relapsing forms of MS, the pharmacological characteristics of these agents often necessitate switching from the better-known intravenous drug ocrelizumab to the subcutaneous agent ofatumumab. This review, illustrated through clinical case examples, discusses the primary reasons for such a switch-both objective (such as insufficient efficacy or intolerance) and subjective. Among the latter, an increasingly relevant factor is the phenomenon of "treatment fatigue" associated with regular intravenous infusions, particularly when therapy has been ongoing for a long period. This fatigue may manifest as feelings of exhaustion or low mood, which negatively impact adherence and, consequently, treatment efficacy.