Evaluation of the humoral response during ocrelizumab therapy in multiple sclerosis — an observational study

INTRODUCTION: Anti-CD20 monoclonal antibodies are widely used as high-efficacy treatment agents (HETAs) in multiple sclerosis (MS). In patients treated with ocrelizumab (OCR), reduced serum IgG levels are a common laboratory abnormality. Infections are among the most frequently observed adverse events during OCR therapy. MATERIAL AND METHODS: We analyzed the humoral immune response during OCR therapy in 52 people with multiple sclerosis (PwMS) and assessed the safety of this treatment, including treatment-related adverse events and infection rates over a period of up to six years. RESULTS: After three years of treatment, immunoglobulin G (IgG) and IgG1 levels decreased, particularly in the relapsing-remitting MS (RMS) group. Higher body mass index (BMI) was associated with lower Ig levels and greater CD19+ cell depletion. Infections were more frequent in patients with relapses within 3 months prior to OCR initiation. Clinical implications/future directions. Ocrelizumab treatment for up to six years showed a manageable safety profile. Given the higher infection risk in patients with greater disease activity, earlier HETA initiation may be beneficial. The association between higher BMI and CD19+ cell depletion warrants further study to support personalized OCR dosing strategies.