A bispecific, humanized monoclonal antibody with potential antineoplastic activity. Mosunetuzumab contains two antigen-recognition sites: one for human CD3, a T-cell surface antigen, and one for human CD20, a tumor-associated antigen (TAA) that is exclusively expressed on B-cells during most stages of B-cell development and is often overexpressed in B-cell malignancies. Upon administration, mosunetuzumab binds to both T-cells and CD20-expressing tumor B-cells; this cross-links T-cells to tumor cells, and may result in a potent cytotoxic T-lymphocyte (CTL) response against CD20-expressing tumor B-cells.