Our results suggest that prototypic bispecific antibodies (a) selectively activate Vγ9+ γδ T cells as judged by CD69 and CD25 surface expression, and intracellular Granzyme B expression, (b) selectively recruit Vγ9+ γδ T cells into cell–cell conjugate formation of γδ T cells with tumor cells indicating selective and effective engagement of effector and target tumor cells, and (c) mediate γδ T cell cytotoxicity (in vitro and in vivo) against tumor antigen-expressing cells. This evidence concerns the gene CD69 and neoplasm.