Recently, the results of non-randomized trials with novel antibody–drug conjugates targeting HER2 (trastuzumab–deruxtecan and trastuzumab–duocarmazine) have suggested a level of efficacy in HER2-low patients with advanced breast cancer, with objective response rates ranging between 32% and 37% in a heavily pretreated population (5, 6). Here, ERBB2 is linked to breast cancer.