This is a humanized IgG1 monoclonal antibody using the same sequences as the therapeutic antibody ocrelizumab. It is a CD20-directed cytolytic antibody indicated for treating patients with primary progressive or relapsing forms of multiple sclerosis (MS). Ocrelizumab is a second-generation recombinant antibody selectively targeting B-cells that express the CD20 antigen. In comparison to non-humanized CD20 antibodies like rituximab, it is anticipated to be less immunogenic upon repeated infusions, thereby improving the benefit-to-risk profile for MS patients. Ocrelizumab binds to an epitope that overlaps with the epitope to which rituximab binds. It has been suggested that ocrelizumab promotes antibody-dependent cellular cytotoxicity and complement-mediated cell lysis while preserving the capacity for B-cell reconstitution and preexisting humoral immunity.