Studies confirmed that T-DXd retains Trastuzumab’s original functions after DXd conjugation: its Fab domain specifically binds HER-2 antigens on tumor cell surface, while the Fc domain engages Fcγ receptors on immune effector cells (e.g., NK cells), thereby resulting in antibody-dependent cellular cytotoxicity (ADCC) effect. This evidence concerns the gene ERBB2 and neoplasm.