Recently, the therapeutic scenario for patients with HER2+ mBC has been revolutionized with the introduction of a new ADC, namely Trastuzumab deruxtecan (T-DXd), which has been specifically engineered to combine an anti-HER2 monoclonal antibody (MoAb) function with the delivery of a potent topoisomerase inhibitor, namely DXd, to cancer cells.7 Here, ERBB2 is linked to cancer.