Ocrelizumab

Ocrelizumab is a humanized monoclonal antibody that depletes CD20-expressing B cells. It is approved to treat relapsing forms of multiple sclerosis and primary progressive multiple sclerosis.

CD20: CD20 is a protein expressed on most mature B cells and targeted by several antibody therapies. Ocrelizumab binds this surface protein to mark B cells for depletion.
Relapsing-remitting multiple sclerosis: Relapsing-remitting multiple sclerosis is a disease course marked by distinct attacks followed by periods of partial or complete recovery. Ocrelizumab is approved for relapsing forms of multiple sclerosis, including this course.
Progressive multifocal leukoencephalopathy: Progressive multifocal leukoencephalopathy is a rare, often fatal brain disease caused by reactivation of JC virus in immunocompromised people. Its rare occurrence during treatment requires vigilance for new or worsening neurological symptoms.
Ofatumumab: Ofatumumab is a fully human anti-CD20 monoclonal antibody administered by subcutaneous injection for relapsing multiple sclerosis. It targets CD20 like ocrelizumab but is self-injected rather than given by infusion.
B cell: A B cell is a lymphocyte involved in antibody production, antigen presentation, and immune regulation. Ocrelizumab reduces a subset of these immune cells without directly targeting plasma cells.
Primary progressive multiple sclerosis: Primary progressive multiple sclerosis is a disease course involving steadily worsening disability from onset, sometimes with temporary plateaus. Ocrelizumab is approved to treat this multiple sclerosis course.
Hypogammaglobulinemia: Hypogammaglobulinemia is an abnormally low concentration of immunoglobulins in the blood. Repeated B-cell depletion can lower immunoglobulin levels and contribute to infections.
Natalizumab: Natalizumab is a monoclonal antibody that blocks α4 integrin to limit immune-cell migration into the central nervous system. It treats relapsing multiple sclerosis through a different immune mechanism and carries a distinct PML risk.
Antibody-dependent cellular cytotoxicity: Antibody-dependent cellular cytotoxicity is immune-cell killing of a target cell coated with antibodies. This effector mechanism contributes to the removal of ocrelizumab-coated B cells.
OPERA I and II: OPERA I and II were phase III trials comparing ocrelizumab with interferon beta-1a in relapsing multiple sclerosis. These trials established its efficacy against relapses and MRI activity in relapsing disease.

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Multiple sclerosisBroader topic: It is a disease-modifying treatment used in relapsing and primary progressive forms.