Antibody-drugconjugates (ADC) such as trastuzumab-emtansine (Kadcyla, Roche) andtrastuzumab-deruxtecan (Enhertu, AstraZeneca) can overcome resistanceto HER2-targeted therapies since their cytotoxic mechanism of actionmakes them highly potent, addressing low or heterogeneous HER2 expression.3 Trastuzumab-deruxtecan has proven effective fortreating BC resistant to trastuzumab4 andretains activity against tumors with low HER2.5 However, resistance to ADCs develops and alternative treatmentswith cytotoxic mechanisms of action are needed.6 Here, ERBB2 is linked to breast cancer.