ofatumumab

Ofatumumab is a human monoclonal antibody that binds to CD20, a protein expressed on the surface of B lymphocytes. By targeting a membrane-proximal epitope on CD20, it promotes depletion of CD20-positive B cells through mechanisms including complement-dependent cytotoxicity, antibody-dependent cellular cytotoxicity, and direct induction of cell death. The drug has two major clinical uses in different disease areas.

In oncology, ofatumumab (brand Arzerra) is approved for the treatment of chronic lymphocytic leukemia (CLL) that has progressed after other therapies. It is administered by intravenous infusion and may be used as monotherapy or as part of combination regimens depending on regional approvals and guidelines.

In neurology, a subcutaneous formulation marketed as Kesimpta is approved for relapsing forms of multiple sclerosis (MS). It is designed for self-administration and is given by monthly injections, following loading doses initiated by clinicians. The MS indication aims to reduce relapses and slow disability progression.

Safety and adverse effects: Commonly reported effects include infusion reactions, infections such as upper respiratory tract infections, and flu-like symptoms. Hepatitis B reactivation risk exists. As with other anti-CD20 antibodies, rare cases of progressive multifocal leukoencephalopathy have been reported. Patients should be screened for hepatitis B and monitored for infections during treatment.

Development and naming: Ofatumumab was developed by Genmab and marketed by GlaxoSmithKline, with distinct product names Arzerra for CLL and Kesimpta for MS.