T-DXd is approved in Canada for the treatment of adult patients with unresectable or metastatic HER2+ breast cancer as a third-line therapy after disease progression following taxanes, trastuzumab + pertuzumab, and trastuzumab-emtansine, as well as for early disease recurrence in the neoadjuvant or adjuvant setting, and for second-line therapy in patients previously treated with taxanes and trastuzumab + pertuzumab [1,2,7]. Here, ERBB2 is linked to breast cancer.