Ofatumumab binds to CD20 and destroys targeted B cells.
Ofatumumab, similar to rituximab and ocrelizumab, binds to CD20 on the surface of B cells resulting in cell death of targeted B cells. However, binding occurs at a different site on CD20 compared to these other drugs, resulting in a stronger bond and longer activity.
Ofatumumab is currently used as a treatment for chronic lymphocytic leukemia.
A phase II study by Dr. Sorensen and colleagues examined the effect of two infusions of ofatumumab (100mg, 300mg or 700mg) or placebo given two weeks apart. Ofatumumab treatment was associated with a significant reduction of B cells. All three doses were found to reduce the number of cumulative lesions, total number of lesions and new/enlarging T2 lesions. A phase II study examining the efficacy of subcutaneous injections of ofatumumab (3mg, 30mg, and 60mg) is underway in RRMS patients. The primary outcome of interest is examining the effect of subcutaneous injection of ofatumumab on brain lesion activity. The scheduled study completion date is 2016.
Future studies will provide further insights into possible adverse effects.
Sorensen PS et al. Magnetic Resonance Imaging (MRI) Efficacy of Ofatumumab in Relapsing-Remitting Multiple Sclerosis (RRMS) – 24-week Results of a Phase II Study. ECTRIMS. 2010; 82(7): 573-81.