Ofatumumab treatment in patients with neuromyelitis optica spectrum disorder: a retrospective multicenter cohort...

Ofatumumab is a fully human anti-CD20 monoclonal antibody that selectively and highly depletes B cells. However, limited data on ofatumumab treatment are available in patients with neuromyelitis optica spectrum disorders (NMOSD). In this study, we aimed to evaluate the efficacy and safety of subcutaneous ofatumumab in patients with NMOSD.

We conducted a retrospective multicenter cohort study of patients with NMOSD who received ofatumumab treatment at 15 tertiary hospitals in China. The primary outcome was the annualized relapse rate (ARR). The secondary outcomes included disability measures (Expanded Disability Status Scale score, EDSS; the Aminoff-Logue Disability Scale, ALS), changes in aquaporin-4 IgG (AQP4-IgG) titers, and safety profiles during ofatumumab treatment.

A total of 112 patients (88% female, median age 44.0 years with interquartile range [IQR 29.5-57.5]) received ofatumumab treatment for a median of 1.7 years (IQR: 1.1-2.0). The median ARR decreased significantly from 2.0 (IQR 0.7-10.0) before ofatumumab to 0 (IQR 0.0-0.0; p < 0.001) after ofatumumab. Twenty-two patients (20%) experienced 25 relapses, with 20 (80%) occurring within the first year of initiating ofatumumab treatment and 19 (76%) classified as minor. The EDSS score from start to the last follow-up also improved significantly (median: pre-treatment 3.5, IQR 2.0-6.5, post-treatment: 2.0, IQR1.0-3.5, p < 0.001). Among 94 patients, 71 (76%) showed reduced AQP4-IgG titers at last follow-up. Injection-related reactions were reported in 13 (12%) of 112 patients. Twenty-four infections occurred in 20 patients (18%) during the ofatumumab treatment, with 92% (22/24) being grade 1 or 2 (CTCAE version 5.0). Only 2 patients (2%) experienced pneumonia requiring hospitalization and recovered after antibiotic treatment (grade 3). Hypogammaglobulinemia was recorded in 14% (13/95) of patients and was not associated with infection.

Subcutaneous ofatumumab treatment significantly reduces the relapse risk, limits worsening of disability, and reduces AQP4-IgG titers in NMOSD. Moreover, the safety profiles were generally acceptable. Further research is necessary to explore the sustained clinical response of ofatumumab in NMOSD.