A novel use and dramatic efficacy of ofatumumab for the treatment of anti-N-methyl-D-aspartate receptor encephalitis: a report of two cases

Ofatumumab (OFA), a subcutaneous anti-CD20 monoclonal antibody, selectively depletes B-cells. The purpose of this study was to report the therapeutic effect and safety of OFA in two refractory anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis cases which were nonresponsive to first-line immunotherapies. Two severely affected anti-NMDAR encephalitis patients (mRS score: 5) with resistance to standard immunotherapies (corticosteroids, IV immunoglobulins) were treated with OFA (3 subcutaneous injections of 20 mg on days 1, 7, 14). The patients' guardians declined plasma exchange (PE) and RTX. The clinical outcome of the patients was followed up for 6 months after the administration of OFA. Treatment with OFA led to rapid clinical improvement accompanied by the enhancement of neuropsychiatric function, disappearance of brain MRI lesions, and decline in partial NMDAR antibody titer. The CD20-positive B-cells were completely depleted in both patients. Moreover, the therapy was well tolerated with no adverse effects. The patients were discharged without clinical deficits and with significantly improved cognition. OFA appeared to be highly effective in the two presented cases despite the limited first-line therapy without PE, which suggests good potential for the application of OFA in this field. However, the lingering effects of previously administered corticosteroids and IV immunoglobulins cannot be excluded.