Ocrevus (ocrelizumab) is a humanized monoclonal antibody approved for the treatment of adults with relapsing forms of multiple sclerosis (including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease) as well as primary progressive multiple sclerosis (PPMS). It is administered by intravenous (IV) infusion, typically every 6 months after the initial two doses. Ocrevus works by selectively targeting CD20-positive B cells, a type of immune cell believed to contribute to the abnormal immune response in MS that causes inflammation and damage to the protective myelin sheath around nerve fibers. By reducing the number of these B cells, Ocrevus helps limit disease activity, slow disability progression, and reduce relapses.