Ocrelizumab in MS patients with persistence of disease activity after alemtuzumab: A multi-center Italian study

Background: The reason why some multiple sclerosis (MS) patients show disease activity after alemtuzumab (ALM) is still unclear, but ocrelizumab (OCR) could represent an interesting sequential therapeutic approach. Objectives: To investigate safety and efficacy of OCR in MS patients with disease activity after two ALM courses. Methods: Observational retrospective multi-centers Italian cohort study. Results: Seventy-two subjects were included. Mean follow-up (FU) was 2.4 (±1) years. Forty-five patients (62.5%) experienced at least one adverse event (AE), with infections accounting for 96.7% of cases. A reduction in total lymphocytes was observed between OCR start and 6 months FU, driven by BCD19+ lymphocytes depletion (p < 0.001). Immunoglobulin M (IgM) levels decreased between OCR start and 6 months FU (p < 0.001). At 2-year FU, relapse, magnetic resonance imaging (MRI) activity and disability worsening-free survival were 92.1%, 90.8%, and 89.2%. The evidence of inflammatory activity between the two ALM courses was associated with higher risk of relapse, MRI activity, and NEDA-3 status loss in relapsing-remitting multiple sclerosis (RRMS; p = 0.02, p = 0.05, p = 0.01, respectively). Conclusions: OCR after two ALM courses seemed to be safe and effective. Early IgM hypogammaglobulinemia occurred in a high proportion of patients. The evidence of inflammatory activity between ALM courses seemed to increase the risk of MS re-activation on OCR treatment.