Tu136 - Intravenous Ofatumumab Treatment of Multiple Sclerosis and Related Disorders: An Observational Study

Ofatumumab is an anti-CD20 monoclonal antibody approved for subcutaneous administration for the treatment of relapsing multiple sclerosis (MS). Intravenously administered ofatumumab has been used off-label for MS and related disorders, but data is limited to a single trial of 38 MS patients receiving one infusion series. The objective of the present study was to assess disease activity and side effects in relation to longer-term intravenous ofatumumab treatment in MS, neuromyelitis optica spectrum disease (NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).

We conducted a retrospective study of patients treated off-label with intravenous ofatumumab for MS, NMOSD or MOGAD at the Danish Multiple Sclerosis Center. Data was retrieved from the Danish Multiple Sclerosis Registry and medical chart review.

Fifty patients were identified (4 with NMOSD, 4 with MOGAD and 42 with MS) with a median treatment duration of 2.2 years. Median annualized relapse rate decreased from 1.0 at baseline to 0.3 during ofatumumab treatment. At 24 months, the probability of having experienced a relapse was 55% and confirmed worsening of disability 7%. Infusion-related reactions were observed in 81% during the first infusion and 35% during the last infusion. Six patients experienced infections requiring hospitalization. De novo low IgM was detected in 10/36 patients, and de novo low IgG in ≤3/35. Extended follow-up for a median of 2.1 years after treatment termination showed no cases of late onset neutropenia.

Our data indicate that intravenous ofatumumab treatment of inflammatory demyelinating disorders reduces frequency of relapses, stabilizes disability, and has an acceptable safety profile.