ERBB2 and neoplasm: Trastuzumab deruxtecan (T-DXd) is a novel antibody-drug conjugate (ADC) composed of three key components: humanized anti-HER2 IgG1 monoclonal antibody (Trastuzumab) for tumor-selective targeted delivery, cleavable tetrapeptide-based linker and potent topoisomerase I inhibitor payload (Deruxtecan) (3).