Two phase III clinical trials randomizing HER2-low-positive metastatic breast cancer patients to receive either Trastuzumab-Deruxtecan or treatment of physician’s choice are currently ongoing and results are pending (NCT03734029—Destiny-Breast04 met its primary endpoint—data not presented yet, NCT04494425—Destiny-Breast06). Here, ERBB2 is linked to breast carcinoma.