Real-world safety and effectiveness of ofatumumab in multiple sclerosis: A clinic-based study in Australia

Background Monoclonal antibodies that target the CD20 antigen and cause B-cell depletion have proven to be a highly effective treatment strategy in relapsing-remitting MS (RRMS). Ofatumumab, the first fully human anti-CD20 monoclonal antibody, was approved for RRMS treatment in 2021 following successful phase III clinical trials. Real-world patient populations are inherently heterogeneous and offer further insights into the impact of therapies on disease activity, adverse events and immunological parameters. Objective To evaluate the safety and effectiveness of ofatumumab in a clinic-based MS population. Methods Adult RRMS patients attending a clinic in Sydney, Australia, treated with ofatumumab were included. A retrospective review of medical records was undertaken. Results A total of 170 patients were enrolled. Mean age was 46.2 years (±11.0). Median duration of treatment with ofatumumab was 18.1 months (11.0–26.0). 96.5% of patients met three-parameter criteria for no evidence of disease activity (NEDA-3) during treatment. No relapses occurred. Eighteen patients had progression independent of relapse activity (PIRA) in the 12 months before ofatumumab, 12 of whom stabilised. Serious infections occurred in 2.9%, and 6.4% stopped treatment due to adverse events. Immunoglobulin levels decreased on treatment, though this was only significant for IgM ( p < .001) and lower levels were not associated with infection. Conclusion This study demonstrates high effectiveness of ofatumumab in an older RRMS population with longer disease duration than pivotal trials. A positive effect on PIRA was observed in 66.7% of those experiencing it in the year prior. Discontinuation due to adverse events was rare.